WorldWideScience

Sample records for arid lands

  1. New crops for arid lands.

    Science.gov (United States)

    Hinman, C W

    1984-09-28

    Five plants are described that could be grown commercially under arid conditions. Once the most valuable component has been obtained from each plant (rubber from guayule; seed oil from jojoba, buffalo gourd, and bladderpod; and resin from gumweed), the remaining material holds potential for useful products as well as fuel. It is difficult to realize the full potential of arid land plants, however, because of the complexities of developing the necessary agricultural and industrial infrastructure simultaneously. To do so, multicompany efforts or cooperative efforts between government and the private sector will be required.

  2. Arid Lands Biofuel

    Science.gov (United States)

    Neupane, B. P.

    2013-05-01

    Dependence on imported petroleum, as well as consequences from burning fossil fuels, has increased the demand for biofuel sources in the United States. Competition between food crops and biofuel crops has been an increasing concern, however, since it has the potential to raise prices for US beef and grain products due to land and resource competition. Biofuel crops that can be grown on land not suitable for food crops are thus attractive, but also need to produce biofuels in a financially sustainable manner. In the intermountain west of Nevada, biofuel crops need to survive on low-organic soils with limited precipitation when grown in areas that are not competing with food and feed. The plants must also yield an oil content sufficiently high to allow economically viable fuel production, including growing and harvesting the crop as well as converting the hydrocarbons into a liquid fuel. Gumweed (Grindelia squarrosa) currently appears to satisfy all of these requirements and is commonly observed throughout the west. The plant favors dry, sandy soils and is most commonly found on roadsides and other freshly disturbed land. A warm season biennial, the gumweed plant is part of the sunflower family and normally grows 2-4 feet high with numerous yellow flowers and curly leaves. The gumweed plant contains a large store of diterpene resins—most abundantly grindelic acid— similar to the saps found on pine trees that are used to make inks and adhesives. The dry weight harvest on the experimental field is 5130 lbs/acre. Whole plant biomass yields between 11-15% (average 13%) biocrude when subjected to acetone extraction whereas the buds alone contains up to a maximum of 35% biocrude when harvested in 'white milky' stage. The extract is then converted to basic form (sodium grindelate) followed by extraction of nonpolar constituents (mostly terpenes) with hexane and extracted back to ethyl acetate in acidified condition. Ethyl acetate is removed under vacuum to leave a dark

  3. Remote Sensing Parameterization of Land Surface Heat Fluxes over Arid and Semi-arid Areas

    Institute of Scientific and Technical Information of China (English)

    马耀明; 王介民; 黄荣辉; 卫国安; MassimoMENENTI; 苏中波; 胡泽勇; 高峰; 文军

    2003-01-01

    Dealing with the regional land surfaces heat fluxes over inhomogeneous land surfaces in arid and semi-arid areas is an important but not an easy issue. In this study, one parameterization method based on satellite remote sensing and field observations is proposed and tested for deriving the regional land surface heat fluxes over inhomogeneous landscapes. As a case study, the method is applied to the Dunhuang experimental area and the HEIFE (Heihe River Field Experiment, 1988-1994) area. The Dunhuang area is selected as a basic experimental area for the Chinese National Key Programme for Developing Basic Sciences: Research on the Formation Mecbanism and Prediction Theory of Severe Climate Disaster in China (G1998040900, 1999-2003). The four scenes of Landsat TM data used in this study are 3 June 2000,22 August 2000, and 29 January 2001 for the Dunhuang area and 9 July 1991 for the HEIFE area. The regional distributions of land surface variables, vegetation variables, and heat fluxes over inhomogeneous landscapes in arid and semi-arid areas are obtained in this study.

  4. New crops for arid lands. [Jojoba; Buffalo gourd; Bladderpod; Gumweed

    Energy Technology Data Exchange (ETDEWEB)

    Hinman, C.W.

    1984-09-28

    Five plants are described that could be grown commercially under arid conditions. Once the most valuable component has been obtained from each plant (rubber from guayule; seed oil from jojoba, buffalo gourd, and bladderpod; and resin from gumweed), the remaining material holds potential for useful products as well as fuel. It is difficult to realize the full potential of arid land plants, however, because of the complexities of developing the necessary agricultural and industrial infrastructure simultaneously. To do so, multicompany efforts or cooperative efforts between government and the private sector will be required.

  5. Land-atmosphere feedbacks amplify aridity increase over land under global warming

    Science.gov (United States)

    Berg, Alexis; Findell, Kirsten; Lintner, Benjamin; Giannini, Alessandra; Seneviratne, Sonia I.; van den Hurk, Bart; Lorenz, Ruth; Pitman, Andy; Hagemann, Stefan; Meier, Arndt; Cheruy, Frédérique; Ducharne, Agnès; Malyshev, Sergey; Milly, P. C. D.

    2016-09-01

    The response of the terrestrial water cycle to global warming is central to issues including water resources, agriculture and ecosystem health. Recent studies indicate that aridity, defined in terms of atmospheric supply (precipitation, P) and demand (potential evapotranspiration, Ep) of water at the land surface, will increase globally in a warmer world. Recently proposed mechanisms for this response emphasize the driving role of oceanic warming and associated atmospheric processes. Here we show that the aridity response is substantially amplified by land-atmosphere feedbacks associated with the land surface's response to climate and CO2 change. Using simulations from the Global Land Atmosphere Coupling Experiment (GLACE)-CMIP5 experiment, we show that global aridity is enhanced by the feedbacks of projected soil moisture decrease on land surface temperature, relative humidity and precipitation. The physiological impact of increasing atmospheric CO2 on vegetation exerts a qualitatively similar control on aridity. We reconcile these findings with previously proposed mechanisms by showing that the moist enthalpy change over land is unaffected by the land hydrological response. Thus, although oceanic warming constrains the combined moisture and temperature changes over land, land hydrology modulates the partitioning of this enthalpy increase towards increased aridity.

  6. How Sustainable are Engineered Rivers in Arid Lands?

    Directory of Open Access Journals (Sweden)

    Jurgen Schmandt

    2013-06-01

    Full Text Available Engineered rivers in arid lands play an important role in feeding the world’s growing population. Each continent has rivers that carry water from distant mountain sources to fertile soil downstream where rainfall is scarce. Over the course of the last century most rivers in arid lands have been equipped with large engineering structures that generate electric power and store water for agriculture and cities. This has changed the hydrology of the rivers. In this paper we discuss how climate variation, climate change, reservoir siltation, changes in land use and population growth will challenge the sustainability of engineered river systems over the course of the next few decades. We use the Rio Grande in North America, where we have worked with Mexican and American colleagues, to describe our methodology and results. Similar work is needed to study future water supply and demand in engineered rivers around the world.

  7. Arid land plants: promising new tools for economic development and basic research

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P.

    1980-01-01

    An overview is presented of arid land plant development stressing products and plant physiological and ecological concepts unique to arid land plants. Integration of new arid land crops into polyculture management systems is suggested utilizing specialized plant functions, e.g., drought resistance, resistance to salinity, ability to fix nitrogen, frost tolerance and capability to produce a cash crop. Impacts on arid land plant productivity on political systems of developing countries are discussed and recommendations are presented for overcoming institutional constraints facing arid land plant development. (MHR)

  8. Land use change and carbon cycle in arid and semi-arid lands of East and Central Asia

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Dramatic changes in land use have occurred in arid and semi-arid landsof Asia during the 20th century. Grassland conversion into croplands and ecosystem degradation is widespread due to the high growth rate of human population and political reforms of pastoral systems. Rangeland degradation made many parts of this region vulnerable to environmental and political changes. The collapse of the livestock sector in some states of central Asia, expansion of livestock inChina and intensive degradation of grasslands in China are examples of the responses of pastoral systems to these changes over the past decades. Carbon dynamics in this region is highly variable in space and time. Land use/cover changes with widespread reduction of forest and grasslands increased carbon emission from the region.

  9. Domesticated proboscidea parviflora: a potential oilseed crop for arid lands

    Energy Technology Data Exchange (ETDEWEB)

    Berry, J.; Bretting, P.K.; Nabhan, G.P.; Weber, C.

    1981-01-01

    Wild and domesticated Proboscidea parviflora were evaluated as oilseed crops for arid lands through chemical and biological analyses. Domesticated plants grown in the Sonoran desert bore seed containing 35-40 per cent oil and 23-27 per cent protein. Yield per hectare was estimated at 1000 kg of oil and 675 kg of protein, quantities which compare favourably with other crops. An ephemeral life cycle and certain characteristics of the fruit and seed allow this plant to grow in xeric habitats unsuitable for many other plants. Several Proboscidea species hybridize with P. parviflora and could be used in future crop breeding. Rapid germination and higher oil and protein content of seed make the domesticated P. parviflora superior to the wild form as a crop. Domesticated P. parviflora thus shows promise as an oilseed crop for the Sonoran Desert and possibly for other arid regions. (Refs. 22).

  10. Mitigating Climate Change in the Arid Lands of Namibia

    Science.gov (United States)

    Schneider, Martin B.; Sorensen, Marten

    2014-05-01

    Mitigating Climate Change in the Arid Lands of Namibia Namibia is the most arid country south of the Sahara, with scarce rainfall and perennial rivers only at its borders, > 80% of the area relies solely on groundwater. This has had devastating economic effects limiting opportunities for sustainable rural livelihoods that keep the population majority living below the World Bank poverty line (IFAD, 2013). A primary example of climatic variability which affects agrarian productivity is increased bush encroachment of Namibia's arid grazing land. The result has been a severe biodiversity loss, increased desertification and diminished water-use efficiency and underground water tables. Given these factors, Namibia's arid lands provide a unique opportunity to assess and test innovative / appropriate adaptation and mitigation strategies. Working toward sustainable management, restoration, and maintenance of balanced, resilient arid ecosystems in Namibia will also be a means to support and expand economic sectors incl. opportunities for job creation and potentially provide a model for similar arid regions. Main vegetation zones are: desert (46%), savannah (37%), and dry woodlands and forests (17%), i.e. management strategies currently used by rural communities. 2. Capture and assess cultural and gender dimensions of management strategies within stakeholder groups using participatory approaches. 3. Determine science-based alternatives for adaptive land management strategies and test their acceptability to local communities and within the current policy framework. 4. Integrate identified indigenous knowledge with appropriate science and new emerging technologies to develop a training toolkit of effective strategies relevant to all stakeholders. 5. Utilize training sessions, education workshops, curriculum revisions, and appropriate information and communication technologies (ICTs) including social media outlets to disseminate the toolkit strategies. 6. Apply a modified logic

  11. Arid land irrigation in the United States Pacific Northwest for 2001

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the extent of arid land irrigation in the Pacific Northwest region of the United...

  12. A brief introduction to Physical Geography of Arid Land in China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A book, Physical Geography of Arid Land in China, mainly edited by Prof. Xi CHEN from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences has been published by Science Press in July of 2010.

  13. Development and use of bioenergy feedstocks for semi-arid and arid lands.

    Science.gov (United States)

    Cushman, John C; Davis, Sarah C; Yang, Xiaohan; Borland, Anne M

    2015-07-01

    Global climate change is predicted to increase heat, drought, and soil-drying conditions, and thereby increase crop sensitivity to water vapour pressure deficit, resulting in productivity losses. Increasing competition between agricultural freshwater use and municipal or industrial uses suggest that crops with greater heat and drought durability and greater water-use efficiency will be crucial for sustainable biomass production systems in the future. Agave (Agavaceae) and Opuntia (Cactaceae) represent highly water-use efficient bioenergy crops that could diversify bioenergy feedstock supply yet preserve or expand feedstock production into semi-arid, abandoned, or degraded agricultural lands, and reclaim drylands. Agave and Opuntia are crassulacean acid metabolism species that can achieve high water-use efficiencies and grow in water-limited areas with insufficient precipitation to support traditional C3 or C4 bioenergy crops. Both Agave and Opuntia have the potential to produce above-ground biomass rivalling that of C3 and C4 crops under optimal growing conditions. The low lignin and high amorphous cellulose contents of Agave and Opuntia lignocellulosic biomass will be less recalcitrant to deconstruction than traditional feedstocks, as confirmed by pretreatments that improve saccharification of Agave. Refined environmental productivity indices and geographical information systems modelling have provided estimates of Agave and Opuntia biomass productivity and terrestrial sequestration of atmospheric CO2; however, the accuracy of such modelling efforts can be improved through the expansion of field trials in diverse geographical settings. Lastly, life cycle analysis indicates that Agave would have productivity, life cycle energy, and greenhouse gas balances comparable or superior to those of traditional bioenergy feedstocks, but would be far more water-use efficient.

  14. Combining Sustainable Land Management Technologies to Combat Land Degradation and Improve Rural Livelihoods in Semi-arid Lands in Kenya.

    Science.gov (United States)

    Mganga, K Z; Musimba, N K R; Nyariki, D M

    2015-12-01

    Drylands occupy more than 80% of Kenya's total land mass and contribute immensely to the national economy and society through agriculture, livestock production, tourism, and wild product harvesting. Dryland ecosystems are areas of high climate variability making them vulnerable to the threats of land degradation. Consequently, agropastoralists inhabiting these ecosystems develop mechanisms and technologies to cope with the impacts of climate variability. This study is aimed to; (1) determine what agropastoralists inhabiting a semi-arid ecosystem in Kenya attribute to be the causes and indicators of land degradation, (2) document sustainable land management (SLM) technologies being undertaken to combat land degradation, and (3) identify the factors that influence the choice of these SLM technologies. Vegetation change from preferred indigenous forage grass species to woody vegetation was cited as the main indicator of land degradation. Land degradation was attributed to recurrent droughts and low amounts of rainfall, overgrazing, and unsustainable harvesting of trees for fuelwood production. However, despite the challenges posed by climate variability and recurrent droughts, the local community is engaging in simple SLM technologies including grass reseeding, rainwater harvesting and soil conservation, and dryland agroforestry as a holistic approach combating land degradation and improving their rural livelihoods. The choice of these SLM technologies was mainly driven by their additional benefits to combating land degradation. In conclusion, promoting such simple SLM technologies can help reverse the land degradation trend, improve agricultural production, food security including access to food, and subsequently improve livelihoods of communities inhabiting dryland ecosystems.

  15. Combining Sustainable Land Management Technologies to Combat Land Degradation and Improve Rural Livelihoods in Semi-arid Lands in Kenya

    Science.gov (United States)

    Mganga, K. Z.; Musimba, N. K. R.; Nyariki, D. M.

    2015-12-01

    Drylands occupy more than 80 % of Kenya's total land mass and contribute immensely to the national economy and society through agriculture, livestock production, tourism, and wild product harvesting. Dryland ecosystems are areas of high climate variability making them vulnerable to the threats of land degradation. Consequently, agropastoralists inhabiting these ecosystems develop mechanisms and technologies to cope with the impacts of climate variability. This study is aimed to; (1) determine what agropastoralists inhabiting a semi-arid ecosystem in Kenya attribute to be the causes and indicators of land degradation, (2) document sustainable land management (SLM) technologies being undertaken to combat land degradation, and (3) identify the factors that influence the choice of these SLM technologies. Vegetation change from preferred indigenous forage grass species to woody vegetation was cited as the main indicator of land degradation. Land degradation was attributed to recurrent droughts and low amounts of rainfall, overgrazing, and unsustainable harvesting of trees for fuelwood production. However, despite the challenges posed by climate variability and recurrent droughts, the local community is engaging in simple SLM technologies including grass reseeding, rainwater harvesting and soil conservation, and dryland agroforestry as a holistic approach combating land degradation and improving their rural livelihoods. The choice of these SLM technologies was mainly driven by their additional benefits to combating land degradation. In conclusion, promoting such simple SLM technologies can help reverse the land degradation trend, improve agricultural production, food security including access to food, and subsequently improve livelihoods of communities inhabiting dryland ecosystems.

  16. Land cover/land use change in semi-arid Inner Mongolia: 1992-2004

    Energy Technology Data Exchange (ETDEWEB)

    John, Ranjeet; Chen Jiquan; Lu Nan; Wilske, Burkhard, E-mail: ranjeet.john@utoledo.ed [Department of Environmental Sciences, University of Toledo, Toledo, OH 43606 (United States)

    2009-10-15

    The semi-arid grasslands in Inner Mongolia (IM) are under increasing stress owing to climate change and rapid socio-economic development in the recent past. We investigated changes in land cover/land use and landscape structure between 1992 and 2004 through the analysis of AVHRR and MODIS derived land cover data. The scale of analysis included the regional level (i.e. the whole of IM) as well as the level of the dominant biomes (i.e. the grassland and desert). We quantified proportional change, rate of change and the changes in class-level landscape metrics using the landscape structure analysis program FRAGSTATS. The dominant land cover types, grassland and barren, 0.47 and 0.27 million km{sup 2}, respectively, have increased proportionally. Cropland and urban land use also increased to 0.15 million km{sup 2} and 2197 km{sup 2}, respectively. However, the results further indicated increases in both the homogeneity and fragmentation of the landscape. Increasing homogeneity was mainly related to the reduction in minority cover types such as savanna, forests and permanent wetlands and increasing cohesion, aggregation index and clumpy indices. Conversely, increased fragmentation of the landscape was based on the increase in patch density and the interspersion/juxtaposition index (IJI). It is important to note the socio-economic growth in this fragile ecosystem, manifested by an increasing proportion of agricultural and urban land use not just at the regional level but also at the biome level in the context of regional climate change and increasing water stress.

  17. A multiscale, hierarchical model of pulse dynamics in arid-land ecosystems

    Science.gov (United States)

    Collins, Scott L.; Belnap, Jayne; Grimm, N. B.; Rudgers, J. A.; Dahm, Clifford N.; D'Odorico, P.; Litvak, M.; Natvig, D. O.; Peters, Douglas C.; Pockman, W. T.; Sinsabaugh, R. L.; Wolf, B. O.

    2014-01-01

    Ecological processes in arid lands are often described by the pulse-reserve paradigm, in which rain events drive biological activity until moisture is depleted, leaving a reserve. This paradigm is frequently applied to processes stimulated by one or a few precipitation events within a growing season. Here we expand the original framework in time and space and include other pulses that interact with rainfall. This new hierarchical pulse-dynamics framework integrates space and time through pulse-driven exchanges, interactions, transitions, and transfers that occur across individual to multiple pulses extending from micro to watershed scales. Climate change will likely alter the size, frequency, and intensity of precipitation pulses in the future, and arid-land ecosystems are known to be highly sensitive to climate variability. Thus, a more comprehensive understanding of arid-land pulse dynamics is needed to determine how these ecosystems will respond to, and be shaped by, increased climate variability.

  18. Arid lands plants as feedstocks for fuels and chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Hoffmann, J.J.

    1983-01-01

    The purpose of this paper is to review the recent research on arid-adapted plants that have potential as producers of fuels or chemicals. The major focus will be on plant species that appear to have commercial value. Research on guayule (Parthenium argentatum) and jojoba (Simmondsia chinensis) will be mentioned only briefly, since these plants have been discussed extensively in the literature, and excellent reviews are already in existence. In this review the literature on arid-adapted plants that have potential uses for solid fuels, liquid fuels, and chemical feedstocks is summarized, followed by an overview of the research directions and types of development that are needed in order for bio-energy production systems to reach the commercial stage. 127 references.

  19. Theoretical critical value curve and driving force formation of ecological migration in the arid land

    Institute of Scientific and Technical Information of China (English)

    ZHU Zi'an; ZHANG Xiaolei

    2006-01-01

    The features of the fragile eco-environment of the arid land decide that its capacity of disturbance-resistance is lower. The natural desert oases in the arid land are in mosaic patches distributed in a wide Gobi desert. The population distribution is greatly dependent on water resources. The population is characterized with dispersed distribution, simple production and living style, and poverty and remoteness. The reason why the ecological migrations are carried out lies in the ecological problems. "Ecological degradation" is the main driving force of the ecological migration. Then, the strength of the driving force depends on the degree of ecological degradation. Hence, whether to carry out ecological migration depends on the extent of ecological degradation.Theoretically, the critical value curve for calculating ecological migration in the arid land is put forward through comprehensive research of relative problems of ecology, economics etc., combined with the ecological migration experience in the arid land, and based on the features of the arid environment. In this article, with this curve, the theoretical research and some practice of the ecological migration have been done from the perspective of natural behavior and governmental behavior of the driving force formation of ecological migration. It analyses the active driving force (factors) and negative forces (factors), and points out the timing and steps of implementing the ecological migration in the arid land. The theoretical curve embodies certain originality and applicability,which provides a quantitative method for evaluating 196the degree of ecological degradation and the theoretical base for implementing ecological migration projects.

  20. Land cover change drives climate extremes and aridity in non-Amazonian South America

    Science.gov (United States)

    Larsen, J.; Salazar, A.; Mcalpine, C. A.; Syktus, J.; Katzfey, J.

    2015-12-01

    Increasing evidence is showing the relevance of land cover change on the regional mean climate. However, the mechanisms that explain these interactions remain a challenge in land - atmosphere interactions science. This challenge is particularly significant in understanding the role of vegetation change on climate extremes and aridity, which has been barely addressed by the literature. In this paper we focus on this gap by investigating the effects of land use and land cover change on selected climate extremes indices and aridity in non-Amazonian South America over an area of about 3 million km2. We run a 3 ensemble climate model nudged with the ERA-Interim reanalysis and stretched to 25 km resolution for present (year 2005) land cover relative to realistic historic vegetation distribution. The most important results of this experiment are that the degree of change in vegetation structure determines whether extreme daytime temperatures will increase or decrease, particularly during the dry season. This is because a large change in surface roughness promotes increased wind speeds and heat advection, whereas a small change in surface roughness does not increase wind and can increase heat build-up in the atmosphere since the sensible heat flux also increases. We also put these results in a wider context of land surface - atmospheric feedbacks by looking at the corresponding change in aridity (precipitation / potential evapotranspiration). This shows the processes that drive the changes in temperature extremes also determine whether significant changes in aridity occur, since all the change in aridity can be prescribed to changes in potential evaporation, or atmospheric water demand. We propose a conceptual model of the mechanisms that explain these alterations which is an advance in understanding land-atmosphere interactions and provides evidence of the main mechanisms responsible of changes in the feedbacks because of changes in natural vegetation.

  1. The first Editorial Board meeting of Journal of Arid Land in 2010 was held in Urumqi

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    On Sep. 5, 2010, the first Editorial Board meeting of Journal of Arid Land (JAL) was held in Urumqi. The director of Xinjiang Institute of Ecology and Geography (XIEG), Chinese Academy of Sciences (CAS) and the editor-in-chief of JAL, Professor Chen Xi, another editor-in-chief, Professor Li Bailian, University of California,

  2. A method of characterizing land-cover swap changes in the arid zone of China

    Institute of Scientific and Technical Information of China (English)

    Yecheng YUAN; Baolin LI; Xizhang GAO; Haijiang LIU; Lili XU; Chenghu ZHOU

    2016-01-01

    Net area change analysis can dramatically underestimate total change of land cover,even sometimes seriously misinterpret ecological processes of the ecosystem,especially in arid or semiarid zones.In this paper,a suite of indices are presented to characterize land-cover swaps that may seriously damage the ecosystem in arid or semiarid zones,based on swap-change areas extracted from remotely sensed images.First,swap percentage of total area and swap intensity of total changes were used to determine the status of land-cover swap change in an area.Then,dominated swap category and individual swapchange intensity for a land-cover category were used to determine flagged land-cover swap-change categories.Finally,swap-change mode and Pielou's index were used to determine the land-cover swap-change processes of dominant categories.A case study is conducted using this approach,based on two land-cover maps in the 1980s and 2000 in Naiman Qi,Tongliao City,Inner Mongolia,China.This study shows that the approach can clearly quantify the severity and flagged classes of land-cover swap-change and reveal their relationship with ecological processes of the ecosystem.These results indicate that the approach can give deep insights into swap change,which can be very valuable to land-cover policy making and management.

  3. New crops for arid lands. [Bladderpod, gumweed, guayule, jojoba, and buffalo gourd

    Energy Technology Data Exchange (ETDEWEB)

    Hinman, C.W.

    1984-09-28

    Five plants are described that could be grown commercially under arid conditions. Once the most valuable component has been obtained from each plant (rubber from guayule; seed oil from jojoba, buffalo gourd, and bladderpod; and resin from gumweed), the remaining material holds potential for useful products as well as fuel. It is difficult to realize the full potential or arid land plants, however, because of the complexities of developing the necessary agricultural and industrial infrastructure simultaneously. To do so, multicompany efforts or cooperative efforts between government and the private sector will be required. 20 references.

  4. Space platform albedo measurements as indicators of change in arid lands

    Science.gov (United States)

    Robinove, C.J.

    1982-01-01

    The change in albedo of arid lands is an indicator of changes in their condition and quality, including density of vegetative cover, erosion, deposition, surficial soil moisture, and man-made change. In general, darkening of an arid land surface indicates an increase in land quality while brightening indicates a decrease in quality, primarily owing to changes in vegetation. Landsat multiband images taken on different dates can be converted to black-and-white albedo images. Subtraction of one image from another, pixel by pixel, results in an albedo change map that can be density sliced to show areas that have brightened or darkened by selected percentages. These maps are then checked in the field to determine the reasons for the changes and to evaluate the changes in land condition and quality. The albedo change mapping technique has been successfully used in the arid lands of western Utah and northern Arizona and has recently been used for detection of coal strip mining activities in northern Alabama. ?? 1983.

  5. Monitoring the hydrologic and vegetation dynamics of arid land with satellite remote sensing and mathematic modeling

    Science.gov (United States)

    Zhan, Xiwu; Gao, Wei; Pan, Xiaoling; Ma, Yingjun

    2003-07-01

    Terrestrial ecosystems, in which carbon is retained in live biomass, play an important role in the global carbon cycling. Among these ecological systems, vegetation and soils in deserts and semi deserts control significant proportions in the total carbon stocks on the land surface and the carbon fluxes between the land surface and the atmosphere (IPCC special report: Land Use, Land Use Change and Forestry, June 2000). Therefore, accurate assessment of the carbon stocks and fluxes of the desert and semi desert areas at regional scales is required in global carbon cycle studies. In addition, vegetative ecosystem in semi-arid and arid land is strongly dependent on the water resources. Monitoring the hydrologic processes of the land is thus also required. This work explores the methodology for the sequential continuous estimation of the carbon stocks, CO2 flux, evapotranspiration, and sensible heat fluxes over desert and semidesert area using data from the Jornada desert in New Mexico, USA. A CO2 and energy flux coupled model is used to estimate CO2, water vapor and sensible heat fluxes over the desert area. The model is driven by the observed meteorological data. Its input land surface parameters are derived from satellite images. Simulated energy fluxes are validated for specific sites with eddy covariance observations. Based on the output of spatially distributed CO2 fluxes, carbon accumulations over the desert area during a period of time is calculated and the contribution of the desert ecosystem to the atmospheric carbon pool is discussed.

  6. Plant-associated microbiomes in arid lands: diversity, ecology and biotechnological potential

    KAUST Repository

    Soussi, Asma

    2015-08-28

    Background: Aridification is a worldwide serious threat directly affecting agriculture and crop production. In arid and desert areas, it has been found that microbial diversity is huge, built of microorganisms able to cope with the environmental harsh conditions by developing adaptation strategies. Plants growing in arid lands or regions facing prolonged abiotic stresses such as water limitation and salt accumulation have also developed specific physiological and molecular stress responses allowing them to thrive under normally unfavorable conditions. Scope: Under such extreme selection pressures, special root-associated bacterial assemblages, endowed with capabilities of plant growth promotion (PGP) and extremophile traits, are selected by the plants. In this review, we provide a general overview on the microbial diversity in arid lands and deserts versus specific microbial assemblages associated with plants. The ecological drivers that shape this diversity, how plant-associated microbiomes are selected, and their biotechnological potential are discussed. Conclusions: Selection and recruitment of the plant associated bacterial assemblages is mediated by the combination of the bio-pedo-agroclimatic conditions and the plant species or varieties. Diversity and functional redundancy of these associated PGPR makes them very active in supporting plant improvement, health and resistance to drought, salt and related stresses. Implementing proper biotechnological applications of the arid and desert-adapted PGPR constitute the challenge to be raised.

  7. New Technologies to Reclaim Arid Lands User's Manual

    Energy Technology Data Exchange (ETDEWEB)

    W. K. Ostler

    2002-10-01

    Approximately 70 percent of all U.S. military training lands are located in arid and semi-arid areas. Training activities in such areas frequently adversely affect vegetation, damaging plants and reducing the resilience of vegetation to recover once disturbed. Fugitive dust resulting from a loss of vegetation creates additional problems for human health, increasing accidents due to decreased visibility, and increasing maintenance costs for roads, vehicles, and equipment. Under conventional technologies to mitigate these impacts, it is estimated that up to 35 percent of revegetation projects in arid areas will fail due to unpredictable natural environmental conditions, such as drought, and reclamation techniques that were inadequate to restore vegetative cover in a timely and cost-effective manner. New reclamation and restoration techniques are needed in desert ranges to help mitigate the adverse effects of military training and other activities to arid-land environments. In 1999, a cooperative effort between the U.S. Department of Energy (DOE), the US. Department of Defense (DoD), and selected university scientists was undertaken to focus on mitigating military impacts in arid lands. As arid lands are impacted due to DoD and DOE activities, biological and soil resources are gradually lost and the habitat is altered. A conceptual model of that change in habitat quality is described for varying levels of disturbance in the Mojave Desert. As the habitat quality degrades and more biological and physical resources are lost from training areas, greater costs are required to return the land to sustainable levels. The purpose of this manual is to assist land managers in recognizing thresholds associated with habitat degradation and provide reclamation planning and techniques that can reduce the costs of mitigation for these impacted lands to ensure sustainable use of these lands. The importance of reclamation planning is described in this manual with suggestions about

  8. Arid land irrigation in the United States Pacific Northwest for 2001 summarized for NHDPlus v2 catchments

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the area of arid land irrigation in the Pacific Northwest region of the United...

  9. Regional Cost Estimates for Reclamation Practices on Arid and Semiarid Lands

    Energy Technology Data Exchange (ETDEWEB)

    W. K. Ostler

    2002-02-01

    The U.S. Army uses the Integrated Training Area Management program for managing training land. One of the major objectives of the Integrated Training Area Management program has been to develop a method for estimating training land carrying capacity in a sustainable manner. The Army Training and Testing Area Carrying Capacity methodology measures training load in terms of Maneuver Impact Miles. One Maneuver Impact Mile is the equivalent impact of an M1A2 tank traveling one mile while participating in an armor battalion field training exercise. The Army Training and Testing Area Carrying Capacity methodology is also designed to predict land maintenance costs in terms of dollars per Maneuver Impact Mile. The overall cost factor is calculated using the historical cost of land maintenance practices and the effectiveness of controlling erosion. Because land maintenance costs and effectiveness are influenced by the characteristics of the land, Army Training and Testing Area Carrying Capacity cost factors must be developed for each ecological region of the country. Costs for land maintenance activities are presented here for the semiarid and arid regions of the United States. Five ecoregions are recognized, and average values for reclamation activities are presented. Because there are many variables that can influence costs, ranges for reclamation activities are also presented. Costs are broken down into six major categories: seedbed preparation, fertilization, seeding, planting, mulching, and supplemental erosion control. Costs for most land reclamation practices and materials varied widely within and between ecological provinces. Although regional cost patterns were evident for some practices, the patterns were not consistent between practices. For the purpose of estimating land reclamation costs for the Army Training and Testing Area Carrying Capacity methodology, it may be desirable to use the ''Combined Average'' of all provinces found in the last

  10. Dynamic Predictions of Semi-Arid Land Cover Change

    Science.gov (United States)

    Foster-Wittig, T. A.

    2011-12-01

    Savannas make up about 18% of the global landmass and contain about 22% of the world's population (Falkenmark and Rockstrom, 2008). They are unique ecosystems in that they consist of both grass and trees. Depending on the land use, amount of precipitation, herbivory, and fire frequency, either trees or grasses can be more prevalent than the other (Sankaran et al., 2005). Savannas in sub-Saharan Africa are usually considered water-limited ecosystems due to the seasonal rainfall. It has been shown that the vegetation responds on a short timescale to the rainfall (Scanlon et al, 2002). Therefore, savannas are foreseen as vulnerable ecosystems to future changes in the land use and climate change (Sankaran et al, 2005). The goal of this research is to quantify the vulnerability of this ecosystem by projecting future changes in the savanna structure due to land use and climate change through the use of a dynamic vegetation model. This research will provide a better understanding of the relationship between precipitation and vegetation in savannas through the use of a Vegetation Dynamics Model developed to predict surface water fluxes and vegetation dynamics in water-limited ecosystems (Williams and Albertson, 2005). In this project, it will be used to model leaf area index (LAI) for point locations within sub-Saharan Africa between Kenya and Botswana with a range of annual rainfall and savanna type. With this model, future projections are developed for what can be anticipated in the future for the savanna structure based on three climate change scenarios; (1) decreased depth, (2) decreased frequency, and (3) decreased wet season length. The effect of the climate change scenarios on the plant water stress and plant water uptake will be analyzed in order to understand the dynamic effects of precipitation on vegetation. Therefore, this will allow conclusions to be drawn about how mean precipitation and a changing climate effect the sensitivity of savanna vegetation. It is

  11. Development of land degradation spectral indices in a semi-arid Mediterranean ecosystem

    Science.gov (United States)

    Chabrillat, Sabine; Kaufmann, Hermann J.; Palacios-Orueta, Alicia; Escribano, Paula; Mueller, Andreas

    2004-10-01

    The goal of this study is to develop remote sensing desertification indicators for drylands, in particular using the capabilities of imaging spectroscopy (hyperspectral imagery) to derive soil and vegetation specific properties linked to land degradation status. The Cabo de Gata-Nijar Natural Park in SE Spain presents a still-preserved semiarid Mediterranean ecosystem that has undergone several changes in landscape patterns and vegetation cover due to human activity. Previous studies have revealed that traditional land uses, particularly grazing, favoured in the Park the transition from tall arid brush to tall grass steppe. In the past ~40 years, tall grass steppes and arid garrigues increased while crop field decreased, and tall arid brushes decreased but then recovered after the area was declared a Natural Park in 1987. Presently, major risk is observed from a potential effect of exponential tourism and agricultural growth. A monitoring program has been recently established in the Park. Several land degradation parcels presenting variable levels of soil development and biological activity were defined in summer 2003 in agricultural lands, calcareous and volcanic areas, covering the park spatial dynamics. Intensive field spectral campaigns took place in Summer 2003 and May 2004 to monitor inter-annual changes, and assess the landscape spectral variability in spatial and temporal dimension, from the dry to the green season. Up to total 1200 field spectra were acquired over ~120 targets each year in the land degradation parcels. The targets were chosen to encompass the whole range of rocks, soils, lichens, and vegetation that can be observed in the park. Simultaneously, acquisition of hyperspectral images was performed with the HyMap sensor. This paper presents preliminary results from mainly the field spectral campaigns. Identifying sources of variability in the spectra, in relation with the ecosystem dynamics, will allow the definition of spectral indicators of

  12. Preface paper to the Semi-Arid Land-Surface-Atmosphere (SALSA) Program special issue

    Science.gov (United States)

    Goodrich, D.C.; Chehbouni, A.; Goff, B.; MacNish, B.; Maddock, T.; Moran, S.; Shuttleworth, W.J.; Williams, D.G.; Watts, C.; Hipps, L.H.; Cooper, D.I.; Schieldge, J.; Kerr, Y.H.; Arias, H.; Kirkland, M.; Carlos, R.; Cayrol, P.; Kepner, W.; Jones, B.; Avissar, R.; Begue, A.; Bonnefond, J.-M.; Boulet, G.; Branan, B.; Brunel, J.P.; Chen, L.C.; Clarke, T.; Davis, M.R.; DeBruin, H.; Dedieu, G.; Elguero, E.; Eichinger, W.E.; Everitt, J.; Garatuza-Payan, J.; Gempko, V.L.; Gupta, H.; Harlow, C.; Hartogensis, O.; Helfert, M.; Holifield, C.; Hymer, D.; Kahle, A.; Keefer, T.; Krishnamoorthy, S.; Lhomme, J.-P.; Lagouarde, J.-P.; Lo, Seen D.; Luquet, D.; Marsett, R.; Monteny, B.; Ni, W.; Nouvellon, Y.; Pinker, R.; Peters, C.; Pool, D.; Qi, J.; Rambal, S.; Rodriguez, J.; Santiago, F.; Sano, E.; Schaeffer, S.M.; Schulte, M.; Scott, R.; Shao, X.; Snyder, K.A.; Sorooshian, S.; Unkrich, C.L.; Whitaker, M.; Yucel, I.

    2000-01-01

    The Semi-Arid Land-Surface-Atmosphere Program (SALSA) is a multi-agency, multi-national research effort that seeks to evaluate the consequences of natural and human-induced environmental change in semi-arid regions. The ultimate goal of SALSA is to advance scientific understanding of the semi-arid portion of the hydrosphere-biosphere interface in order to provide reliable information for environmental decision making. SALSA approaches this goal through a program of long-term, integrated observations, process research, modeling, assessment, and information management that is sustained by cooperation among scientists and information users. In this preface to the SALSA special issue, general program background information and the critical nature of semi-arid regions is presented. A brief description of the Upper San Pedro River Basin, the initial location for focused SALSA research follows. Several overarching research objectives under which much of the interdisciplinary research contained in the special issue was undertaken are discussed. Principal methods, primary research sites and data collection used by numerous investigators during 1997-1999 are then presented. Scientists from about 20 US, five European (four French and one Dutch), and three Mexican agencies and institutions have collaborated closely to make the research leading to this special issue a reality. The SALSA Program has served as a model of interagency cooperation by breaking new ground in the approach to large scale interdisciplinary science with relatively limited resources.

  13. Impact of climate change on arid lands agriculture

    Directory of Open Access Journals (Sweden)

    El-Beltagy Adel

    2012-04-01

    Full Text Available Abstract The planet earth, on which we live in communities, is being increasingly 'ruptured' because of human activities; its carrying capacity is under great stress because of demographic pressures. The pressure is especially affecting the people living in the dry areas because of the marginal and fragile nature of the resources they have access to. There are over 2,000 million hectares of land that have been degraded, with a loss of agrobiodiversity, increased water scarcity and increased natural resource destruction. Superimposed on this is the fact that the neglectful and exploitive use of natural resources has set the train of global climate change in motion. It is anticipated that the impact of climate change will cut across all boundaries. Crops, cropping systems, rotations and biota will undergo transformation. To maintain the balance in the system, there is a need for new knowledge, alternative policies and institutional changes. The marginalized people in dry areas are likely to be most seriously hit by the shifts in moisture and temperature regimes as a result of the global climate change. To help them cope with the challenges, there is a need for a new paradigm in agricultural research and technology transfer that makes full use of modern science and technology in conjunction with traditional knowledge. This necessitates more investment by international agencies and national governments for supporting the relevant integrated research and sustainable development efforts, with full participation of the target communities. Only such an approach can enable the vulnerable communities of the dryland areas to use the natural resources in a sustainable manner and thus help protect the environment for future generations. The clock is ticking and the future of the world lies in the collective responsibility and wisdom of all nations on this planet. This should be reflected in the endorsement of a solid future plan.

  14. An overview of the spatial patterns of land surface processes over arid and semiarid regions

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    With data from the project Collaborative Observation of Semi-arid/Arid Regions in North China, collected during July and September 2008, the spatial patterns of land surface processes over arid and semiarid regions have been investigated based on the ordinary Kriging interpolation approach. Generally, for the radiation processes, downward and upward short-wave radiation have a uniformly increasing trend with latitude, but the spatial patterns of long-wave radiation present notable regional differences: both upward and downward long-wave radiation increase with latitude in the west of North China, while in the east they vary inversely with latitude, suggesting surface temperature and clouds respectively have feedbacks to the long-wave radiation in the west and east of North China. The surface net radiation basically has a negative latitudinal trend. Long-wave radiation budget plays an important role in the spatial pattern of surface net radiation, particularly in the east of North China, although short-wave radiation budget largely determines the magnitude of surface net radiation. For the energy processes, latent and sensible heat flux varies conversely with latitude: more available land surface energy is consumed by evaporating soil water at lower latitudes while more is used for heating the atmosphere at higher latitudes. A soil heat flux maximum and minimum are found in Loess Plateau and Qinghai Plateau respectively, and a maximum is seen in the northeast China.

  15. Temporal and spatial variability response of groundwater level to land use/land cover change in oases of arid areas

    Institute of Scientific and Technical Information of China (English)

    YAN Jinfeng; CHEN Xi; LUO Geping; GUO Quanjun

    2006-01-01

    This paper conducts a case study on the impacts of land use/cover change (LUCC) on the temporal and spatial variability of the groundwater level in an arid oasis in the Sangong River Watershed by using the geographical information system (GIS),remote sensing (RS) and geostatistical methods. The temporal and spatial variability of the groundwater level in the watershed in 1978, 1987 and 1998 is regressed by using thesemivariogram model and Kriging interpolation. The LUCC classification maps derived from the aerial images in 1978, Landsat TM image in 1987 and Landsat ETM image in 1998 are used to superpose and analyze the conversion relationship of LUCC types in the regions with different isograms of the groundwater depth. The results show that the change of groundwater recharge was not so significant in the whole oasis, but the temporal and spatial LUCC was significant either in the normal flow periods or in the high flow periods during the 20-year period from 1978 to 1998, and there was a close correlation between them. There is generally a moderate spatial correlation of groundwater level (33.4%),and the spatial autocorrelation distance is 17.78 km.The regions where the groundwater level is sharply changed are also the regions where the land resources are increasingly exploited, which include mainly the exploitation of farmlands, woodlands, and building, industrial and mining lands. The study reveals that the LUCC affects strongly the temporal and spatial variability of the groundwater level in the arid oasis. The study results are of direct and practical significance for rationally utilizing shallow groundwater resources and maintaining the stability of the arid oasis.

  16. Status of corrective measures technology for shallow land burial at arid sites

    Science.gov (United States)

    Abeele, W. V.; Nyhan, J. W.; Drennon, B. J.; Lopez, E. A.; Herrera, W. J.; Langhorst, G. J.

    The field research program involving corrective measure technologies for arid shallow land burial sites is described. Soil erosion and infiltration of water into a simulated trench cap with various surface treatments was measured and compared with similar data from agricultural systems across the United States. Report of field testing of biointrusion barriers continues at a closed-out waste disposal site at Los Alamos. Final results of an experiment designed to determine the effects of subsidence on the performance of a cobble-gravel biobarrier system are reported, as well as the results of hydrologic modeling activities involving biobarrier systems.

  17. Spectral mixture analysis (SMA and change vector analysis (CVA methods for monitoring and mapping land degradation/desertification in arid and semiarid areas (Sudan, using Landsat imagery

    Directory of Open Access Journals (Sweden)

    Abdelrahim A.M. Salih

    2017-04-01

    Full Text Available The severe Sahel catastrophe in 1968–1974 as well as repeated famines and food shortage that have hit many African countries during the 1970s have highlighted the need for further research concerning land degradation and environmental monitoring in arid and semi-arid areas. Land degradation, and desertification processes in arid and semi-arid environment were increased in the last four decades, especially in the developing countries like Sudan. To test to what extent remote sensing and geographical information science (GIS methodologies and techniques could be used for monitoring changes in arid and semi-arid regions and environment, these methodologies have long been suggested as a time and cost-efficient method. In this frame, spectral Mixture Analysis (SMA, Object-based oriented classification (Segmentation, and Change Vector Analysis are recently much recommended as a most suitable method for monitoring and mapping land cover changes in arid and semi-arid environment. Therefor the aim of this study is to use these methods and techniques for environmental monitoring with emphasis on desertification and to find model that can describe and map the status and rate of desertification processes and land cover changes in semi-arid areas in White Nile State (Sudan by using multi-temporal imagery of the Landsat satellite TM (1987, TM (2000, and ETM+ (2014 respectively. The paper also discusses and evaluates the efficiency of the adapted methodologies in monitoring the land degradation processes and changes in the arid and semi-arid regions.

  18. Water Resources Response to Climate and Land-Cover Changes in a Semi-Arid Watershed, New Mexico, USA

    Directory of Open Access Journals (Sweden)

    Joonghyeok Heo

    2015-01-01

    Full Text Available This research evaluates a climate-land cover-water resources interconnected system in a semi-arid watershed with minimal human impact from 1970 - 2009. We found _ increase in temperature and 10.9% decrease in precipitation. The temperature exhibited a lower increase trend and precipitation showed a similar decrease trend compared to previous studies. The dominant land-cover change trend was grass and forest conversion into bush/shrub and developed land and crop land into barren and grass land. These alterations indicate that changes in temperature and precipitation in the study area may be linked to changes in land cover, although human intervention is recognized as the major land-cover change contributor for the short term. These alterations also suggest that decreasing human activity in the study area leads to developed land and crop land conversion into barren and grass land. Hydrological responses to climate and land-cover changes for surface runoff, groundwater discharge, soil water content and evapotranspiration decreased by 10.2, 10.0, 4.1, and 10.5%, respectively. Hydrological parameters generally follow similar trends to that of precipitation in semi-arid watersheds with minimal human development. Soil water content is sensitive to land-cover change and offset relatively by the changes in precipitation.

  19. Development of technology for the design of shallow land burial facilities at arid sites

    Science.gov (United States)

    Nyhan, J. W.; Abeele, W. V.; Drennon, B. J.; Herrera, W. J.; Lopez, E. A.; Langhorst, G. J.; Stallings, E. A.; Walker, R. D.; Martinez, J. L.

    The Los Alamos field research program involving technology development for arid shallow land burial (SLB) sites is described. Field data are presented for an integrated field experiment, which was designed to test individual SLB component experiments related to erosion control, biobarriers, and subsurface capillary and migration barriers. Field tests of biointrusion barriers at waste disposal sites and in experimental plots are reported. The results of a joint DOE/NRC experiment to evaluate leaching and transport of sorbing (Cs, Sr, Li) and nonsorbing (I, Br) solutes in sandy silt backfill are presented for steady-state and unsteady-state flow conditions. A capillary barrier experiment performed in a large caisson (3-m diameter, 6.1 m deep) is described and a year's worth of field data is presented.

  20. Development of technology for the design of shallow land burial facilities at arid sites

    Energy Technology Data Exchange (ETDEWEB)

    Nyhan, J.W.; Abeele, W.V.; Drennon, B.J.; Herrera, W.J.; Lopez, E.A.; Langhorst, G.J.; Stallings, E.A.; Walker, R.D.; Martinez, J.L.

    1985-01-01

    The Los Alamos field research program involving technology development for arid shallow land burial (SLB) sites is described. Field data are presented for an integrated field experiment, which was designed to test individual SLB component experiments related to erosion control, biobarriers, and subsurface capillary and migration barriers. Field tests of biointrusion barriers at waste disposal sites and in experimental plots are reported. The results of a joint DOE/NRC experiment to evaluate leaching and transport of sorbing (Cs, Sr, Li) and nonsorbing (I, Br) solutes in sandy silt backfill are presented for steady-state and unsteady-state flow conditions. A capillary barrier experiment performed in a large caisson (3-m diameter, 6.1 m deep) is described and a year's worth of field data is presented.

  1. Ecological Analysis of Deserti Fication Processes in Semi Arid Land in Algeria Using Satellite Data

    Science.gov (United States)

    Zegrar, Ahmed

    2016-07-01

    Desertification, a phenomenon of loss of productivity of the land is both a matter of Environment and Development (Cornet, 2002). It is linked to the anthropogenic action and to climate variability but also to changes in biodiversity, in particular the Maghreb (Hobbs et al., 1995). The desertification of the steppe areas of North Africa (Algeria, Morocco and Tunisia) is considered of special concern by the specialists in these regions. Desertification, Climate Change and the erosion of biodiversity are the central issues for the development of arid, semi-­arid. In this region, the combination of two factors, climatic and anthropogenic, has fostered a deterioration of the vegetation cover, soil erosion and the scarcity of water resources. The climate of this region is characterized by periods of recurring droughts since the 1970s. The anthropogenic pressure is the result of a combination of factors among which the strong demographic growth, the intensification and extension of production systems agro-­pastoral or still further the concentration of a growing livestock on smaller spaces. In this study, the criteria for classification and identification of physical parameters for spatial ecological analysis of vegetation in the steppe region to determine the degradation and vulnerability vegetation formations and how to conduct to phenomenon of desertification. So we use some satellite data in different dates (LANDSAT) in order to determine the ecological of steppe formation and changes in land cover, sand moving and forest deterioration. The application of classification and some arithmetic combination with NDVI and MSAVI2 through specific processes was used to characterize the main steppe formations. An ecological analysis of plant communities and impact of sand move describe the nature of the desertification phenomenon and allow us to determine the impact of factors of climate and entropic activity in the Algerian steppe.

  2. TOWARDS A REMOTE SENSING BASED ASSESSMENT OF LAND SUSCEPTIBILITY TO DEGRADATION: EXAMINING SEASONAL VARIATION IN LAND USE-LAND COVER FOR MODELLING LAND DEGRADATION IN A SEMI-ARID CONTEXT

    Directory of Open Access Journals (Sweden)

    G. Mashame

    2016-06-01

    Full Text Available Land degradation (LD is among the major environmental and anthropogenic problems driven by land use-land cover (LULC and climate change worldwide. For example, poor LULC practises such as deforestation, livestock overstocking, overgrazing and arable land use intensification on steep slopes disturbs the soil structure leaving the land susceptible to water erosion, a type of physical land degradation. Land degradation related problems exist in Sub-Saharan African countries such as Botswana which is semi-arid in nature. LULC and LD linkage information is still missing in many semi-arid regions worldwide.Mapping seasonal LULC is therefore very important in understanding LULC and LD linkages. This study assesses the impact of seasonal LULC variation on LD utilizing Remote Sensing (RS techniques for Palapye region in Central District, Botswana. LULC classes for the dry and rainy seasons were classified using LANDSAT 8 images at Level I according to the Food and Agriculture Organization (FAO International Organization of Standardization (ISO code 19144. Level I consists of 10 LULC classes. The seasonal variations in LULC are further related to LD susceptibility in the semi-arid context. The results suggest that about 985 km² (22% of the study area is susceptible to LD by water, major LULC types affected include: cropland, paved/rocky material, bare land, built-up area, mining area, and water body. Land degradation by water susceptibility due to seasonal land use-land cover variations is highest in the east of the study area where there is high cropland to bare land conversion.

  3. Towards a Remote Sensing Based Assessment of Land Susceptibility to Degradation: Examining Seasonal Variation in Land Use-Land Cover for Modelling Land Degradation in a Semi-Arid Context

    Science.gov (United States)

    Mashame, Gofamodimo; Akinyemi, Felicia

    2016-06-01

    Land degradation (LD) is among the major environmental and anthropogenic problems driven by land use-land cover (LULC) and climate change worldwide. For example, poor LULC practises such as deforestation, livestock overstocking, overgrazing and arable land use intensification on steep slopes disturbs the soil structure leaving the land susceptible to water erosion, a type of physical land degradation. Land degradation related problems exist in Sub-Saharan African countries such as Botswana which is semi-arid in nature. LULC and LD linkage information is still missing in many semi-arid regions worldwide.Mapping seasonal LULC is therefore very important in understanding LULC and LD linkages. This study assesses the impact of seasonal LULC variation on LD utilizing Remote Sensing (RS) techniques for Palapye region in Central District, Botswana. LULC classes for the dry and rainy seasons were classified using LANDSAT 8 images at Level I according to the Food and Agriculture Organization (FAO) International Organization of Standardization (ISO) code 19144. Level I consists of 10 LULC classes. The seasonal variations in LULC are further related to LD susceptibility in the semi-arid context. The results suggest that about 985 km² (22%) of the study area is susceptible to LD by water, major LULC types affected include: cropland, paved/rocky material, bare land, built-up area, mining area, and water body. Land degradation by water susceptibility due to seasonal land use-land cover variations is highest in the east of the study area where there is high cropland to bare land conversion.

  4. Transitions in Land Use Architecture under Multiple Human Driving Forces in a Semi-Arid Zone

    Directory of Open Access Journals (Sweden)

    Issa Ouedraogo

    2015-07-01

    Full Text Available The present study aimed to detect the main shifts in land-use architecture and assess the factors behind the changes in typical tropical semi-arid land in Burkina Faso. Three sets of time-series LANDSAT data over a 23-year period were used to detect land use changes and their underpinning drivers in multifunctional but vulnerable ecologies. Group discussions in selected villages were organized for mapping output interpretation and collection of essential drivers of change as perceived by local populations. Results revealed profound changes and transitions during the study period. During the last decade, shrub and wood savannahs exhibited high net changes (39% and −37% respectively with a weak net positive change for cropland (only 2%, while cropland and shrub savannah exhibited high swap (8% and 16%. This suggests that the area of cropland remained almost unchanged but was subject to relocation, wood savannah decreased drastically, and shrub savannah increased exponentially. Cropland exhibited a null net persistence while shrub and wood savannahs exhibited positive and negative net persistence (1.91 and −10.24, respectively, indicating that there is movement toward agricultural intensification and wood savannah tended to disappear to the benefit of shrub savannah. Local people are aware of the changes that have occurred and support the idea that illegal wood cutting and farming are inappropriate farming practices associated with immigration; absence of alternative cash generation sources, overgrazing and increasing demand for wood energy are driving the changes in their ecosystems. Policies that integrate restoration and conservation of natural ecosystems and promote sustainable agroforestry practices in the study zone are highly recommended.

  5. Pluralism and ethnic conflict in Tanzania's arid lands: the case of the Maasai and the WaArusha.

    Science.gov (United States)

    Ole Kuney, R O

    1994-01-01

    In Tanzania, the Maasai and Waarusha tribes are experiencing conflict because differences in their modes of productions and economic strategies undermine the peaceful coexistence that they have enjoyed since the 18th century. The Maasai are pastoralists, while the Waarusha are agricultural subsistence farmers who are encroaching on the best pasture lands. A sketch of the history of the two groups shows that the Maasai reached the peak of their land holding in 1880 before the arrival of European colonists who seized land and restricted the Maasai to a semi-arid reserve but allowed the Maasai to remain an autonomous and powerful group. The Waarusha began encroaching on Maasai land after independence due to land and population pressure. While closely tied, each group looks down on the other, and Maasai ascendancy has given way to Waarusha challenges. After independence, the tribal and ethnic rule that was protected by the colonial system was disrupted to allow for increased internal migration and new patterns of settlement. The rights of land ownership were transferred from tribes to the State, allowing privileged groups to benefit. The Waarusha began to engage in illegal land-grabbing and to encroach on the Maasai preserve using legal and illegal means. The Maasai view land as collective property and have had difficulty retaining title of traditional lands in the face of population pressure. This loss of grazing land has forced the Maasai into a mixed economy that depends upon agricultural production as well as livestock production. In the meantime, the Waarusha have deliberately sought political office to gain power to secure their holdings. Immediate action is needed to produce 1) a policy on spontaneous settlement, 2) an immediate adjustment of legal procedures for land acquisition, 3) a land tenure policy that equally emphasizes agricultural and livestock production, and 4) controls on undue expansion of subsistence agriculture into semi-arid rangelands.

  6. On the sensitivity of Land Surface Temperature estimates in arid irrigated lands using MODTRAN

    KAUST Repository

    Rosas, Jorge

    2015-11-29

    Land surface temperature (LST) derived from thermal infrared (TIR) satellite data has been reliably used as a remote indicator of evapotranspiration (ET) and surface moisture status. However, in order to retrieve the ET with an accuracy approaching 10%, LST should be retrieved to within 1 ◦C or better, disregarding other elements of uncertainty. The removal of atmospheric effects is key towards achieving a precise estimation of LST and it requires detailed information on water vapor. The Thermal Infrared Sensor (TIRS) onboard Landsat 8 captures data in two long wave thermal bands with 100-meter resolution. However, the US Geological Survey has reported a calibration problem of TIRS bands caused by stray light, resulting in a higher bias in one of its two bands (4% in band 11, 2% in band 10). Therefore, split-window algorithms for the estimation of LST might not be reliable. Our work will focus on the impact of using different atmospheric profiles (e.g. weather prediction models, satellite) for the estimation of LST derived from MODTRAN by using one of the TIRS bands onboard Landsat 8 (band 10). Sites with in-situ measurements of LST are used as evaluation sources. Comparisons between the measured LST and LST derived based on different atmospheric profile inputs to MODTRAN are carried out from 2 Landsat-overpass days (DOY 153 and 160 2015). Preliminary results show a mean absolute error of around 3 ◦C between in-situ and estimated LST over two different crops (alfalfa and carrot) and bare soil.

  7. A "win-win" scenario: the use of sustainable land management technologies to improve rural livelihoods and combat desertification in semi-arid lands in Kenya

    Science.gov (United States)

    Mganga, Kevin; Musimba, Nashon; Nyariki, Dickson; Nyangito, Moses; Mwang'ombe, Agnes

    2014-05-01

    Dryland ecosystems support over 2 billion people and are major providers of critical ecosystems goods and services globally. However, desertification continues to pose a serious threat to the sustainability of the drylands and livelihoods of communities inhabiting them. The desertification problem is well exemplified in the arid and semi-arid lands (ASALs) in Kenya which cover approximately 80% of the total land area. This study aimed to 1) determine what agropastoralists attribute to be the causes of desertification in a semi-arid land in Kenya, 2) document sustainable land management (SLM) technologies being undertaken to improve livelihoods and combat desertification, and 3) identify the factors that influence the choice of the sustainable land management (SLM) technologies. Results show that agropastoralists inhabiting the semi-arid lands in southeastern Kenya mainly attribute desertification to the recurrent droughts and low amounts of rainfall. Despite the challenges posed by desertification and climate variability, agropastoralists in the study area are using a combination of SLM technologies notably dryland agroforestry using drought tolerant species (indigenous and exotic), grass reseeding using perennial native and drought tolerant grass species (vegetation reestablishment) and in-situ rainwater harvesting to improve livelihoods and by extension combat desertification. Interestingly, the choice and adoption of these SLM technologies is influenced more by the additional benefits the agropastoralists can derive from them. Therefore, it is rationale to conclude that success in dryland restoration and combating desertification lies in programs and technologies that offer a "win-win" scenario to the communities inhabiting the drylands. Key words: Agroforestry; Agropastoralists; Drylands; Grass Reseeding; Rainwater Harvesting

  8. Land degradation assessment by geo-spatially modeling different soil erodibility equations in a semi-arid catchment.

    Science.gov (United States)

    Saygın, Selen Deviren; Basaran, Mustafa; Ozcan, Ali Ugur; Dolarslan, Melda; Timur, Ozgur Burhan; Yilman, F Ebru; Erpul, Gunay

    2011-09-01

    Land degradation by soil erosion is one of the most serious problems and environmental issues in many ecosystems of arid and semi-arid regions. Especially, the disturbed areas have greater soil detachability and transportability capacity. Evaluation of land degradation in terms of soil erodibility, by using geostatistical modeling, is vital to protect and reclaim susceptible areas. Soil erodibility, described as the ability of soils to resist erosion, can be measured either directly under natural or simulated rainfall conditions, or indirectly estimated by empirical regression models. This study compares three empirical equations used to determine the soil erodibility factor of revised universal soil loss equation prediction technology based on their geospatial performances in the semi-arid catchment of the Saraykoy II Irrigation Dam located in Cankiri, Turkey. A total of 311 geo-referenced soil samples were collected with irregular intervals from the top soil layer (0-10 cm). Geostatistical analysis was performed with the point values of each equation to determine its spatial pattern. Results showed that equations that used soil organic matter in combination with the soil particle size better agreed with the variations in land use and topography of the catchment than the one using only the particle size distribution. It is recommended that the equations which dynamically integrate soil intrinsic properties with land use, topography, and its influences on the local microclimates, could be successfully used to geospatially determine sites highly susceptible to water erosion, and therefore, to select the agricultural and bio-engineering control measures needed.

  9. Agave proves to be a low recalcitrant lignocellulosic feedstock for biofuels production on semi-arid lands

    Science.gov (United States)

    2014-01-01

    Background Agave, which is well known for tequila and other liquor production in Mexico, has recently gained attention because of its attractive potential to launch sustainable bioenergy feedstock solutions for semi-arid and arid lands. It was previously found that agave cell walls contain low lignin and relatively diverse non-cellulosic polysaccharides, suggesting unique recalcitrant features when compared to conventional C4 and C3 plants. Results Here, we report sugar release data from fungal enzymatic hydrolysis of non-pretreated and hydrothermally pretreated biomass that shows agave to be much less recalcitrant to deconstruction than poplar or switchgrass. In fact, non-pretreated agave has a sugar release five to eight times greater than that of poplar wood and switchgrass . Meanwhile, state of the art techniques including glycome profiling, nuclear magnetic resonance (NMR), Simon’s Stain, confocal laser scanning microscopy and so forth, were applied to measure interactions of non-cellulosic wall components, cell wall hydrophilicity, and enzyme accessibility to identify key structural features that make agave cell walls less resistant to biological deconstruction when compared to poplar and switchgrass. Conclusions This study systematically evaluated the recalcitrant features of agave plants towards biofuels applications. The results show that not only does agave present great promise for feeding biorefineries on semi-arid and arid lands, but also show the value of studying agave’s low recalcitrance for developments in improving cellulosic energy crops. PMID:24708685

  10. Burning crop residues under no-till in semi-arid land, Northern Spain - effects on soil organic matter, aggregation, and earthwor populations.

    NARCIS (Netherlands)

    Virto, I.; Imaz, M.J.; Enrique, A.; Hoogmoed, W.B.; Bescansa, P.

    2007-01-01

    Stubble burning has traditionally been used in semi-arid land for pest and weed control, and to remove the excess of crop residues before seeding in no-tillage systems. We compared differences in soil properties in a long-term (10 years) tillage trial on a carbonated soil in semi-arid north-east Spa

  11. Evidence for micronutrient limitation of biological soil crusts: Importance to arid-lands restoration

    Science.gov (United States)

    Bowker, M.A.; Belnap, J.; Davidson, D.W.; Phillips, S.L.

    2005-01-01

    Desertification is a global problem, costly to national economies and human societies. Restoration of biological soil crusts (BSCs) may have an important role to play in the reversal of desertification due to their ability to decrease erosion and enhance soil fertility. To determine if there is evidence that lower fertility may hinder BSC recolonization, we investigated the hypothesis that BSC abundance is driven by soil nutrient concentrations. At a regional scale (north and central Colorado Plateau, USA), moss and lichen cover and richness are correlated with a complex water-nutrient availability gradient and have approximately six-fold higher cover and approximately two-fold higher species richness on sandy soils than on shale-derived soils. At a microscale, mosses and lichens are overrepresented in microhabitats under the north sides of shrub canopies, where water and nutrients are more available. At two spatial scales, and at the individual species and community levels, our data are consistent with the hypothesis that distributions of BSC organisms are determined largely by soil fertility. The micronutrients Mn and Zn figured prominently and consistently in the various analyses, strongly suggesting that these elements are previously unstudied limiting factors in BSC development. Structural-equation modeling of our data is most consistent with the hypothesis of causal relationships between the availability of micronutrients and the abundance of the two major nitrogen (N) fixers of BSCs. Specifically, higher Mn availability may determine greater Collema tenax abundance, and both Mn and Zn may limit Collema coccophorum; alternative causal hypotheses were less consistent with the data. We propose experimental trials of micronutrient addition to promote the restoration of BSC function on disturbed lands. Arid lands, where BSCs are most prevalent, cover ???40% of the terrestrial surface of the earth; thus the information gathered in this study is potentially useful

  12. Detection and prediction of land cover changes using Markov chain model in semi-arid rangeland in western Iran.

    Science.gov (United States)

    Fathizad, Hassan; Rostami, Noredin; Faramarzi, Marzban

    2015-10-01

    The study of changes and destruction rate in the previous years as well as the possibility of prediction of these changes in the following years has a key role in optimal planning, controlling, and restricting non-normative changes in the future. This research was approached to detecting land use/cover changes (1985-2007) and to forecast the changes in the future (2021) use of multitemporal satellite imagery in semi-arid area in western Iran. A supervised classification of multilayer perceptron (MLP) was applied for detecting land use changes. The study area was classified into five classes, those of forest, rangeland, agriculture, residential, and barren lands. The change detection analysis indicated a decreasing trend in forest cover by 30.42%, while other land uses were increased during 1985 to 2007. The land use changes were predicted using Markov chain model for 2021. The model was calibrated by comparing the simulated map with the real detected classes of land cover in 2007. Then, for further model processing, an acceptable accuracy at 83% was achieved between them. Finally, land use changes were predicted by using transition matrix derived from calibrated approach. The findings of this study demonstrate a rapid change in land use/cover for the coming years. Transforming the forest into other land uses especially rangeland and cropland is the main land cover changes in the future. Therefore, the planning of protection and restoration of forest cover should be an essential program for decision-makers in the study area.

  13. Coupled Soil Water and Heat Transport Near the Land Surface in Arid and Semiarid Regions - Multi-Domain Modeling

    Science.gov (United States)

    Mohanty, Binayak; Yang, Zhenlei

    2016-04-01

    Understanding and simulating coupled water and heat transfer appropriately in the shallow subsurface is of vital significance for accurate prediction of soil evaporation that would improve the coupling between land surface and atmosphere, which consequently could enhance the reliability of weather as well as climate forecast. The theory of Philip and de Vries (1957), accounting for water vapor diffusion only, was considered physically incomplete and consequently extended and improved by several researchers by explicitly taking water vapor convection, dispersion or air flow into account. It is generally believed that the soil moisture is usually low in the near surface layer under highly transient field conditions, particularly in arid and semiarid regions, and that accurate characterization of water vapor transport is critical when modeling simultaneous water and heat transport in the shallow field soils. The first objective of this study is thus mainly to test existing coupled water and heat transport theories and to develop reasonable and simplified numerical models using field experimental data collected under semi-arid and arid hydro-climatic conditions. In addition, more complex multi-domain models are developed for ubiquitous heterogeneous terrestrial surfaces such as horizontal textural contrasts or structured heterogeneity including macropores (fractures, cracks, root channels, etc.). This would make coupled water and heat transfer models applicable in such non-homogeneous soils more meaningful and enhance the skill of land-atmosphere interaction models at a larger context.

  14. On the operationalization of a spatially explicit evaluation of the complexity of land use trajectories in semi-arid Mediterranean agro-ecosystems

    DEFF Research Database (Denmark)

    Nainggolan, Doan

    This thesis aims to unpack the complexity of trajectories of land use change in semi-arid Mediterranean agro-ecosystems – illustrated using findings from the Torrealvilla catchment in south-eastern Spain. The research looks at multiple dimensions of land use change and addresses the past, present...

  15. Hydrological response to land cover changes and human activities in arid regions using a geographic information system and remote sensing.

    Directory of Open Access Journals (Sweden)

    Shereif H Mahmoud

    Full Text Available The hydrological response to land cover changes induced by human activities in arid regions has attracted increased research interest in recent decades. The study reported herein assessed the spatial and quantitative changes in surface runoff resulting from land cover change in the Al-Baha region of Saudi Arabia between 1990 and 2000 using an ArcGIS-surface runoff model and predicted land cover and surface runoff depth in 2030 using Markov chain analysis. Land cover maps for 1990 and 2000 were derived from satellite images using ArcGIS 10.1. The findings reveal a 26% decrease in forest and shrubland area, 28% increase in irrigated cropland, 1.5% increase in sparsely vegetated land and 0.5% increase in bare soil between 1990 and 2000. Overall, land cover changes resulted in a significant decrease in runoff depth values in most of the region. The decrease in surface runoff depth ranged from 25-106 mm/year in a 7020-km2 area, whereas the increase in such depth reached only 10 mm/year in a 243-km2 area. A maximum increase of 73 mm/year was seen in a limited area. The surface runoff depth decreased to the greatest extent in the central region of the study area due to the huge transition in land cover classes associated with the construction of 25 rainwater harvesting dams. The land cover prediction revealed a greater than twofold increase in irrigated cropland during the 2000-2030 period, whereas forest and shrubland are anticipated to occupy just 225 km2 of land area by 2030, a significant decrease from the 747 km2 they occupied in 2000. Overall, changes in land cover are predicted to result in an annual increase in irrigated cropland and dramatic decline in forest area in the study area over the next few decades. The increase in surface runoff depth is likely to have significant implications for irrigation activities.

  16. Hydrological response to land cover changes and human activities in arid regions using a geographic information system and remote sensing.

    Science.gov (United States)

    Mahmoud, Shereif H; Alazba, A A

    2015-01-01

    The hydrological response to land cover changes induced by human activities in arid regions has attracted increased research interest in recent decades. The study reported herein assessed the spatial and quantitative changes in surface runoff resulting from land cover change in the Al-Baha region of Saudi Arabia between 1990 and 2000 using an ArcGIS-surface runoff model and predicted land cover and surface runoff depth in 2030 using Markov chain analysis. Land cover maps for 1990 and 2000 were derived from satellite images using ArcGIS 10.1. The findings reveal a 26% decrease in forest and shrubland area, 28% increase in irrigated cropland, 1.5% increase in sparsely vegetated land and 0.5% increase in bare soil between 1990 and 2000. Overall, land cover changes resulted in a significant decrease in runoff depth values in most of the region. The decrease in surface runoff depth ranged from 25-106 mm/year in a 7020-km2 area, whereas the increase in such depth reached only 10 mm/year in a 243-km2 area. A maximum increase of 73 mm/year was seen in a limited area. The surface runoff depth decreased to the greatest extent in the central region of the study area due to the huge transition in land cover classes associated with the construction of 25 rainwater harvesting dams. The land cover prediction revealed a greater than twofold increase in irrigated cropland during the 2000-2030 period, whereas forest and shrubland are anticipated to occupy just 225 km2 of land area by 2030, a significant decrease from the 747 km2 they occupied in 2000. Overall, changes in land cover are predicted to result in an annual increase in irrigated cropland and dramatic decline in forest area in the study area over the next few decades. The increase in surface runoff depth is likely to have significant implications for irrigation activities.

  17. The potential of intercropping food crops and energy crop to improve productivity of a degraded agriculture land in arid tropics

    Directory of Open Access Journals (Sweden)

    I.K.D. Jaya

    2014-04-01

    Full Text Available Degraded agricultural lands in the arid tropics have low soil organic carbon (SOC and hence low productivity. Poor farmers that their livelihoods depend highly on these types of lands are suffering. Cropping strategies that are able to improve the soil productivity are needed. In the present study, some intercropping models of food crops with bio-energy crop of castor (Ricinus communis L. were tested to assess their potential to improve the degraded land productivity. The intercropping models were: (1 castor - hybrid maize, (2 castor – short season maize, (3 castor – mungbean, and (4 castor –short season maize – mungbean. The results show that yields of the component crops in monoculture were relatively the same as in intercropping, resulted in a high Land Equivalent Ratio (LER. The highest LER (3.07 was calculated from intercropping castor plants with short season maize crops followed by mungbean with intercropping productivity of IDR 15,097,600.00 ha-1. Intercropping has a great potential to improve degraded agriculture land productivity and castor is a promising plant to improve biodiversity and area coverage on the land.

  18. Using hydrogel filled, embedded tubes to sustain grass transplants for arid land restoration

    Science.gov (United States)

    Grass restoration on remote arid rangelands may require irrigation to stimulate seedling establishment. However, irrigation on undeveloped sites is costly. In this study, the survival, growth, and development of Bouteloua eriopoda seedlings irrigated with either starch- or acrylic-based hydrogels c...

  19. Effects of land use/land cover and climate changes on surface runoff in a semi-humid and semi-arid transition zone in northwest China

    Science.gov (United States)

    Yin, Jing; He, Fan; Jiu Xiong, Yu; Qiu, Guo Yu

    2017-01-01

    Water resources, which are considerably affected by land use/land cover (LULC) and climate changes, are a key limiting factor in highly vulnerable ecosystems in arid and semi-arid regions. The impacts of LULC and climate changes on water resources must be assessed in these areas. However, conflicting results regarding the effects of LULC and climate changes on runoff have been reported in relatively large basins, such as the Jinghe River basin (JRB), which is a typical catchment (> 45 000 km2) located in a semi-humid and arid transition zone on the central Loess Plateau, northwest China. In this study, we focused on quantifying both the combined and isolated impacts of LULC and climate changes on surface runoff. We hypothesized that under climatic warming and drying conditions, LULC changes, which are primarily caused by intensive human activities such as the Grain for Green Program, will considerably alter runoff in the JRB. The Soil and Water Assessment Tool (SWAT) was adopted to perform simulations. The simulated results indicated that although runoff increased very little between the 1970s and the 2000s due to the combined effects of LULC and climate changes, LULC and climate changes affected surface runoff differently in each decade, e.g., runoff increased with increased precipitation between the 1970s and the 1980s (precipitation contributed to 88 % of the runoff increase). Thereafter, runoff decreased and was increasingly influenced by LULC changes, which contributed to 44 % of the runoff changes between the 1980s and 1990s and 71 % of the runoff changes between the 1990s and 2000s. Our findings revealed that large-scale LULC under the Grain for Green Program has had an important effect on the hydrological cycle since the late 1990s. Additionally, the conflicting findings regarding the effects of LULC and climate changes on runoff in relatively large basins are likely caused by uncertainties in hydrological simulations.

  20. An approach for land suitability evaluation using geostatistics, remote sensing, and geographic information system in arid and semiarid ecosystems.

    Science.gov (United States)

    Emadi, Mostafa; Baghernejad, Majid; Pakparvar, Mojtaba; Kowsar, Sayyed Ahang

    2010-05-01

    This study was undertaken to incorporate geostatistics, remote sensing, and geographic information system (GIS) technologies to improve the qualitative land suitability assessment in arid and semiarid ecosystems of Arsanjan plain, southern Iran. The primary data were obtained from 85 soil samples collected from tree depths (0-30, 30-60, and 60-90 cm); the secondary information was acquired from the remotely sensed data from the linear imaging self-scanner (LISS-III) receiver of the IRS-P6 satellite. Ordinary kriging and simple kriging with varying local means (SKVLM) methods were used to identify the spatial dependency of soil important parameters. It was observed that using the data collected from the spectral values of band 1 of the LISS-III receiver as the secondary variable applying the SKVLM method resulted in the lowest mean square error for mapping the pH and electrical conductivity (ECe) in the 0-30-cm depth. On the other hand, the ordinary kriging method resulted in a reliable accuracy for the other soil properties with moderate to strong spatial dependency in the study area for interpolation in the unstamped points. The parametric land suitability evaluation method was applied on the density points (150 x 150 m(2)) instead of applying on the limited representative profiles conventionally, which were obtained by the kriging or SKVLM methods. Overlaying the information layers of the data was used with the GIS for preparing the final land suitability evaluation. Therefore, changes in land characteristics could be identified in the same soil uniform mapping units over a very short distance. In general, this new method can easily present the squares and limitation factors of the different land suitability classes with considerable accuracy in arbitrary land indices.

  1. Recycled Urban Wastewater for Irrigation of Jatropha curcas L. in Abandoned Agricultural Arid Land

    Directory of Open Access Journals (Sweden)

    María Dorta-Santos

    2014-10-01

    Full Text Available In a global context in which obtaining new energy sources is of paramount importance, the production of biodiesel from plant crops is a potentially viable alternative to the use of fossil fuels. Among the species used to produce the raw material for biodiesel, Jatropha curcas L. (JCL has enjoyed increased popularity in recent years, due partly to its ability to grow in degraded zones and under arid and semi-arid conditions. The present study evaluates the potential for JCL production under irrigation with non-conventional water resources in abandoned agricultural soils of the island of Fuerteventura (Canary Islands, Spain, which is one of the most arid parts of the European Union. JCL growth and productivity are compared during the first 39 months of cultivation in two soil types (clay-loam and sandy-loam and with two irrigation water qualities: recycled urban wastewater (RWW and desalinated brackish water (DBW. The results indicate that JCL growth (in terms of plant height and stem diameter was significantly influenced both by soil type and water quality, with better development observed in the sandy-loam soil under RWW irrigation. Productivity, measured as cumulative seed production, was not affected by soil type but was affected by water quality. Production under RWW irrigation was approximately seven times greater than with DBW (mean ~2142 vs. 322 kg·ha−1. The higher nutrient content, especially P, K and Mg, and lower B content of the RWW were found to be key factors in the greater productivity observed under irrigation with this type of water.

  2. Response of soil nutrients to different cropping systems in the oasis of arid land

    Institute of Scientific and Technical Information of China (English)

    XU Wenqiang; LUO Geping; CHEN Xi

    2006-01-01

    In the process of transformation of tropic rain forest and semi-arid grassland to farmland, the soil degradation usually occurs. But the transformation of arid desert to oasis is likely to differ from that of tropic rain forest and semi-arid grassland. Taking an alluvial plain oasis as a study case, the oasis soil properties during the process of the transformation of different cropping systems have been investigated and evaluated. Selected cropping systems consist of saline tolerance crop (STC), food crop (FC), melon and vegetables (MV), Economic plants-cotton (EP-C),economic plants-grape (EP-G), Economic plants-Hop (EP-H). Surface soil (0-20 cm) samples were collected in 1982, 1999 and 2003. Soil, organic matter (OM), and available N (AN), available P (AP) and available K (AK) were determined for each soil sample. SPSS statistical software was used to analyze the soil property data. The transformation of cropping systems in the Sangong River watershed was affected directly by the policy, law and market. The soil OM contents experienced a decline during 1982-1999, then a rise during 1999-2003. AN, AP and AK contents increased significantly with cultivated time.Soil OM tends to decrease during the conversion from STC and FC to cotton but increase during the conversion from the cotton to the grape. The soil OM was increased gradually with the cultivation time, so the oasis soil presented carbon sink, which indicates that human activities was reasonable and favorable for improvement of the oasis-ecosystem.

  3. Novel ideas for maximising dew collection to aid plant establishment to combat desertification and restore degraded dry and arid lands

    Science.gov (United States)

    Kotzen, Benz

    2014-05-01

    This paper focuses on the potential of dew to provide water to plants and potentially to people as well in remote and difficult to reach areas where rainfall and underground water cannot be harvested. The combat of desertification and the restoration of degraded and desertified dry and arid lands has never been more urgent. A key practical component of this strategy is the restoration of habitat with planting. But for habitat and planting to survive there needs to be an adequate supply of water. In most cases providing water to the plant's roots is vital. In some areas where habitats have been destroyed, sufficient water is immediately available, for example through seasonal rainfall, or it can be harvested to concentrate adequate supplies of water to the roots. However, in arid and hyper arid areas, as well as in some dryland areas, a consistent and adequate supply of water cannot be provided by any conventional proven method. Thus, as the need to combat desertification and to restore desertified dry and arid land increases, so the need to find novel methods of establishing and maintaining planting and thus habitat increases. In more traditional land management scenarios this can be achieved through manipulating landform on a micro and macro scale, for example, by creating catchments, thereby collecting precipitation and directing it to the plants. Where this cannot be done, other means of water supply are usually required. Bainbridge (2007) and others have shown that supplying water to plants is possible through a number of traditional methods, for example, using clay pots. But most of these techniques require an introduced source of water, for example, obtained through water harvesting methods or by delivering water to site in tanks and by water bowser. This can work but requires continuous manpower. It is expensive and can be physically prohibitive in areas where access is difficult and/or remote. The concept of using dew to supply water in drylands is not new

  4. Simulating the hydrologic impacts of land cover and climate changes in a semi-arid watershed

    Data.gov (United States)

    U.S. Environmental Protection Agency — Changes in climate and land cover are among the principal variables affecting watershed hydrology. This paper uses a cell-based model to examine the hydrologic...

  5. Evaluating the use of sharpened land surface temperature for daily evapotranspiration estimation over irrigated crops in arid lands

    KAUST Repository

    Rosas, Jorge

    2014-12-01

    Satellite remote sensing provides data on land surface characteristics, useful for mapping land surface energy fluxes and evapotranspiration (ET). Land-surface temperature (LST) derived from thermal infrared (TIR) satellite data has been reliably used as a remote indicator of ET and surface moisture status. However, TIR imagery usually operates at a coarser resolution than that of shortwave sensors on the same satellite platform, making it sometimes unsuitable for monitoring of field-scale crop conditions. This study applies the data mining sharpener (DMS; Gao et al., 2012) technique to data from the Moderate Resolution Imaging Spectroradiometer (MODIS), which sharpens the 1 km thermal data down to the resolution of the optical data (250-500 m) based on functional LST and reflectance relationships established using a flexible regression tree approach. The DMS approach adopted here has been enhanced/refined for application over irrigated farming areas located in harsh desert environments in Saudi Arabia. The sharpened LST data is input to an integrated modeling system that uses the Atmosphere-Land Exchange Inverse (ALEXI) model and associated flux disaggregation scheme (DisALEXI) in conjunction with model reanalysis data and remotely sensed data from polar orbiting (MODIS) and geostationary (MSG; Meteosat Second Generation) satellite platforms to facilitate daily estimates of evapotranspiration. Results are evaluated against available flux tower observations over irrigated maize near Riyadh in Saudi Arabia. Successful monitoring of field-scale changes in surface fluxes are of importance towards an efficient water use in areas where fresh water resources are scarce and poorly monitored. Gao, F.; Kustas, W.P.; Anderson, M.C. A Data Mining Approach for Sharpening Thermal Satellite Imagery over Land. Remote Sens. 2012, 4, 3287-3319.

  6. Land Surface Model and Particle Swarm Optimization Algorithm Based on the Model-Optimization Method for Improving Soil Moisture Simulation in a Semi-Arid Region.

    Directory of Open Access Journals (Sweden)

    Qidong Yang

    Full Text Available Improving the capability of land-surface process models to simulate soil moisture assists in better understanding the atmosphere-land interaction. In semi-arid regions, due to limited near-surface observational data and large errors in large-scale parameters obtained by the remote sensing method, there exist uncertainties in land surface parameters, which can cause large offsets between the simulated results of land-surface process models and the observational data for the soil moisture. In this study, observational data from the Semi-Arid Climate Observatory and Laboratory (SACOL station in the semi-arid loess plateau of China were divided into three datasets: summer, autumn, and summer-autumn. By combing the particle swarm optimization (PSO algorithm and the land-surface process model SHAW (Simultaneous Heat and Water, the soil and vegetation parameters that are related to the soil moisture but difficult to obtain by observations are optimized using three datasets. On this basis, the SHAW model was run with the optimized parameters to simulate the characteristics of the land-surface process in the semi-arid loess plateau. Simultaneously, the default SHAW model was run with the same atmospheric forcing as a comparison test. Simulation results revealed the following: parameters optimized by the particle swarm optimization algorithm in all simulation tests improved simulations of the soil moisture and latent heat flux; differences between simulated results and observational data are clearly reduced, but simulation tests involving the adoption of optimized parameters cannot simultaneously improve the simulation results for the net radiation, sensible heat flux, and soil temperature. Optimized soil and vegetation parameters based on different datasets have the same order of magnitude but are not identical; soil parameters only vary to a small degree, but the variation range of vegetation parameters is large.

  7. LAND SUITABILITY SCENARIOS FOR ARID COASTAL PLAINS USING GIS MODELING: SOUTHWESTERN SINAI COASTAL PLAIN, EGYPT

    Directory of Open Access Journals (Sweden)

    Ahmed Wahid

    2009-01-01

    Full Text Available Site selection analysis was carried out to find the best suitable lands for development activities in an example of promising coastal plains, southwestern Sinai, Egypt. Two GIS models were developed to represent two scenarios of land use suitability in the study area using GIS Multi Criteria Analysis Modeling. The factors contributed in the analysis are the Topography, Land cover, Existing Land use, Flash flood index, Drainage lines and Water points. The first scenario was to classify the area according to various gradual ranges of suitability. According to this scenario, the area is classified into five classes of suitability. The percentage of suitability values are 51.16, 6.13, 22.32, 18.49 and 1.89% for unsuitable, least suitable, low suitable, suitable and high suitable, respectively. The second scenario is developed for a particular kind of land use planning; tourism and recreation projects. The suitability map of this scenario was classified into five values. Unsuitable areas represent 51.18% of the study area, least suitable 16.67%, low suitable 22.85%, suitable 8.61%, and high suitable 0.68%. The best area for locating development projects is the area surrounding El-Tor City and close to the coast. This area could be an urban extension of El-Tor City with more economical and environmental management.

  8. LAND SUITABILITY SCENARIOS FOR ARID COASTAL PLAINS USING GIS MODELING: SOUTHWESTERN SINAI COASTAL PLAIN, EGYPT

    Directory of Open Access Journals (Sweden)

    Ahmed Mohamed Wahid

    2009-12-01

    Full Text Available Site selection analysis was carried out to find the best suitable lands for development activities in an example of promising coastal plains, southwestern Sinai, Egypt. Two GIS models were developed to represent two scenarios of land use suitability in the study area using GIS Multi Criteria Analysis Modeling. The factors contributed in the analysis are the Topography, Land cover, Existing Land use, Flash flood index, Drainage lines and Water points. The first scenario was to classify the area according to various gradual ranges of suitability. According to this scenario, the area is classified into five classes of suitability. The percentage of suitability values are 51.16, 6.13, 22.32, 18.49 and 1.89% for unsuitable, least suitable, low suitable, suitable and high suitable, respectively. The second scenario is developed for a particular kind of land use planning; tourism and recreation projects. The suitability map of this scenario was classified into five values. Unsuitable areas represent 51.18% of the study area, least suitable 16.67%, low suitable 22.85%, suitable 8.61%, and high suitable 0.68%. The best area for locating development projects is the area surrounding El-Tor City and close to the coast. This area could be an urban extension of El-Tor City with more economical and environmental management.

  9. GRACE Gravity Satellite Observations of Terrestrial Water Storage Changes for Drought Characterization in the Arid Land of Northwestern China

    Directory of Open Access Journals (Sweden)

    Yanping Cao

    2015-01-01

    Full Text Available Drought is a complex natural hazard which can have negative effects on agriculture, economy, and human life. In this paper, the primary goal is to explore the application of the Gravity Recovery and Climate Experiment (GRACE gravity satellite data for the quantitative investigation of the recent drought dynamic over the arid land of northwestern China, a region with scarce hydrological and meteorological observation datasets. The spatiotemporal characteristics of terrestrial water storage changes (TWSC were first evaluated based on the GRACE satellite data, and then validated against hydrological model simulations and precipitation data. A drought index, the total storage deficit index (TSDI, was derived on the basis of GRACE-recovered TWSC. The spatiotemporal distributions of drought events from 2003 to 2012 in the study region were obtained using the GRACE-derived TSDI. Results derived from TSDI time series indicated that, apart from four short-term (three months drought events, the study region experienced a severe long-term drought from May 2008 to December 2009. As shown in the spatial distribution of TSDI-derived drought conditions, this long-term drought mainly concentrated in the northwestern area of the entire region, where the terrestrial water storage was in heavy deficit. These drought characteristics, which were detected by TSDI, were consistent with local news reports and other researchers’ results. Furthermore, a comparison between TSDI and Standardized Precipitation Index (SPI implied that GRACE TSDI was a more reliable integrated drought indicator (monitoring agricultural and hydrological drought in terms of considering total terrestrial water storages for large regions. The GRACE-derived TSDI can therefore be used to characterize and monitor large-scale droughts in the arid regions, being of special value for areas with scarce observations.

  10. Soil moisture variability and land use in a seasonally arid environment

    Science.gov (United States)

    Williams, A. G.; Ternan, J. L.; Fitzjohn, C.; de Alba, S.; Perez-Gonzalez, A.

    2003-02-01

    Soil moisture patterns were recorded for six different land uses, including oak forest, matorral scrub, olives, and a cultivated field, in central Spain during 1998-99. Volumetric water content was determined using time domain reflectometry at more than 140 sites in each, extending across a range of topographic units. Soil moisture content was a function of land use, with the oak forest being wetter than either the matorral shrubby area or the cultivated site. The spatial patterns for a wet period were kriged and are presented as interpolated contour plots. Geo-statistical analysis confirmed that the patterns were highly heterogeneous, as the variograms showed a pure nugget for each land use, except for the two olive sites, where some spatial structure could be observed. During the investigation the soils were in the dry state and the soil moisture distribution was controlled by local factors; it was not possible to determine which environmental factor had the most influence.

  11. Biocrude crop production in arid lands. [Calotropis procera, Chrysothamus paniculatus, Euphorbia lathyris, Grindelia camporum

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, S.P.; Kingsolver, B.E.; Hoffmann, J.J.

    1983-01-01

    Published and unpublished estimates of land and water requirements and energy yield were used to prepare energy budgets for 4 potential biocrude (liquid fuel) crops in the SW USA: the perennials Calotropis procera and Chrysothamnus paniculatus and the annuals Euphorbia lathyris and Grindelia camporum. Estimated annual costs are examined and discussed for an operation processing 300,000 t/yr. The cheapest energy was produced by C. paniculatus, although it required the largest land area. The paper emphasizes that selecting for biocrude content (biomass quality) of plants may be at the expense of productivity (quantity) since the 2 have been shown to be inversely related in many cases. 8 references.

  12. Modelling the topsoil carbon stock of agricultural lands with the Stochastic Gradient Treeboost in a semi-arid Mediterranean region

    KAUST Repository

    Schillaci, Calogero

    2016-10-29

    ETM+ panchromatic Band 8 were the most important predictors of SOC stock. Finally, SOC stocks were estimated for each land cover class. SGT predicted SOC stock better than GSOC and ISRIC for most data. This resulted in a percentage of data in the prediction confidence interval ± 50% compared to the observed values of 71.4%, 65.8%, and 50.7% for SGT, GSOC, and SGT, respectively. This consisted of a higher R2 and a slope (β) that was closer to 1 for the pseudo-regression constructed with SGT compared to GSOC and ISRIC. In conclusion, the results of the present study showed that the integration of RS with climatic and soil texture spatial data could strongly improve SOC prediction in a semi-arid Mediterranean region. In addition, the panchromatic band of Landsat 7 ETM + was more predictive compared to the conventionally used NDVI. This information is crucial to guiding decision-making processes, especially at a regional scale and/or in semi-arid Mediterranean areas. The model performance of the SGT could be further improved by adopting predictors with greater spatial resolutions. The results of the present experiment yield valuable information, especially for assessing climate change or land use change scenarios for SOC stocks and their spatial distribution.

  13. Pentachlorophenol Degradation by Janibacter sp., a New Actinobacterium Isolated from Saline Sediment of Arid Land

    Directory of Open Access Journals (Sweden)

    Amel Khessairi

    2014-01-01

    Full Text Available Many pentachlorophenol- (PCP- contaminated environments are characterized by low or elevated temperatures, acidic or alkaline pH, and high salt concentrations. PCP-degrading microorganisms, adapted to grow and prosper in these environments, play an important role in the biological treatment of polluted extreme habitats. A PCP-degrading bacterium was isolated and characterized from arid and saline soil in southern Tunisia and was enriched in mineral salts medium supplemented with PCP as source of carbon and energy. Based on 16S rRNA coding gene sequence analysis, the strain FAS23 was identified as Janibacter sp. As revealed by high performance liquid chromatography (HPLC analysis, FAS23 strain was found to be efficient for PCP removal in the presence of 1% of glucose. The conditions of growth and PCP removal by FAS23 strain were found to be optimal in neutral pH and at a temperature of 30°C. Moreover, this strain was found to be halotolerant at a range of 1–10% of NaCl and able to degrade PCP at a concentration up to 300 mg/L, while the addition of nonionic surfactant (Tween 80 enhanced the PCP removal capacity.

  14. Pentachlorophenol degradation by Janibacter sp., a new actinobacterium isolated from saline sediment of arid land.

    Science.gov (United States)

    Khessairi, Amel; Fhoula, Imene; Jaouani, Atef; Turki, Yousra; Cherif, Ameur; Boudabous, Abdellatif; Hassen, Abdennaceur; Ouzari, Hadda

    2014-01-01

    Many pentachlorophenol- (PCP-) contaminated environments are characterized by low or elevated temperatures, acidic or alkaline pH, and high salt concentrations. PCP-degrading microorganisms, adapted to grow and prosper in these environments, play an important role in the biological treatment of polluted extreme habitats. A PCP-degrading bacterium was isolated and characterized from arid and saline soil in southern Tunisia and was enriched in mineral salts medium supplemented with PCP as source of carbon and energy. Based on 16S rRNA coding gene sequence analysis, the strain FAS23 was identified as Janibacter sp. As revealed by high performance liquid chromatography (HPLC) analysis, FAS23 strain was found to be efficient for PCP removal in the presence of 1% of glucose. The conditions of growth and PCP removal by FAS23 strain were found to be optimal in neutral pH and at a temperature of 30 °C. Moreover, this strain was found to be halotolerant at a range of 1-10% of NaCl and able to degrade PCP at a concentration up to 300 mg/L, while the addition of nonionic surfactant (Tween 80) enhanced the PCP removal capacity.

  15. Stress resistance strategy in an arid land shrub: interactions between developmental instability and fractal dimention

    Science.gov (United States)

    Escos, J.; Alados, C.L.; Pugnaire, F. I.; Puigdefábregas, J.; Emlen, J.

    2000-01-01

    This paper investigates allocation of energy to mechanisms that generate and preserve architectural forms (i.e. developmental stability, complexity of branching patterns) and productivity (growth and reproduction) in response to environmental disturbances (i.e. grazing and resource availability). The statistical error in translational symmetry was used to detect random intra-individual variability during development. This can be thought of as a measure of developmental instability caused by stress. Additionally, we use changes in fractal complexity and shoot distribution of branch structures as an alternate indicator of stress. These methods were applied to Anthyllis cytisoides L., a semi-arid environment shrub, to ascertain the effect of grazing and slope exposure on developmental traits in a 2×2 factorial design. The results show that A. cytisoidesmaintains developmental stability at the expense of productivity. Anthyllis cytisoides was developmentally more stable when grazed and when on south-facing, as opposed to north-facing slopes. On the contrary, shoot length, leaf area, fractal dimension and reproductive-to-vegetative allocation ratio were larger in north- than in south-facing slopes. As a consequence, under extreme xeric conditions, shrub mortality increased in north-facing slopes, especially when not grazed. The removal of transpiring area and the reduction of plant competition favoured developmental stability and survival in grazed plants. Differences between grazed and ungrazed plants were most evident in more mesic (north-facing) areas.

  16. Social-biophysical feedbacks and land change in an arid rangeland region

    Science.gov (United States)

    Studies of human-dominated ecosystems have traditionally externalized human agents and their behavior. Rangelands of the southwestern U.S. are no exception: in spite of century-long studies of vegetation change, the specific role of human decisions and their feedbacks with land condition are unknown...

  17. Land-surface and boundary layer processes in a semi-arid heterogeneous landscape

    NARCIS (Netherlands)

    Jochum, A.M.

    2003-01-01

    The European Field Experiment in a Desertification-threatened Area (EFEDA) provides a comprehensive land-surface dataset for a semiarid Mediterranean environment. It is used here to study heat and moisture transport processes in the atmospheric boundary layer (ABL), to derive grid-scale surface flux

  18. Estimation of water requirement per unit carbon fixed by Eucalyptus camaldulensis in semi-arid land of Western Australia

    Institute of Scientific and Technical Information of China (English)

    T. Kojima; Y. Tanaka; S. Katoh; K. Tahara; N. Takahashi; K, Yamada

    2002-01-01

    Afforestation in arid land is a promising method for carbon fixation, but the effective utili-zation of water is highly important and required. Thus, the evaluation of the amount of water perunit carbon fixed with the tree growth is required to minimize the amount of water supplied to theplants. In this research, a tree is regarded as a carbon fixation reactor with inflows of water andnutrients from roots, and CO2 as the carbon source from leaves with outflow of water vapor fromleaves and accumulation in the tree itself. In the process of photosynthesis and respiration nutri-tional elements are dissolved in water flow in trees. They do not flow out by these reactions, butare accumulated in trees. Thus, we have treated the behaviour of nutrients as a marker to evaluatethe water/carbon ratio. Assuming that nutrient concentration is constant in sap, and the differences in the ratios ofnutrient to carbon in living trees and dead (i.e. litter fall, etc.) are negiected, the ratio of the usedwater to fixed carbon is given as the ratio of nutrient to carbon in the tree body divided by the ratioof nutrient to water in sap. However, some nutrients are translocated and concentrated within thetree and some may be discarded through litter fall. Thus it is important to examine which nutrientelement is the most suitable as the tracer. In this paper, the results of the above method applied to Eucalyptus camaldulensis in semi-arid land of Western Australia are shown. The value of water requirement per unit carbon fixationdetermined from potassium balance is between 421 kg-H2O/kg-C for mature trees and 285kg-H2O/k9-C for young trees, while the values from calcium balance are much larger than these.The cause of the discrepancy between these values is discussed based on the measured elementconcentrations in sap and trees and the plant physiology. Finally, the actual average value throughthe life of a tree is suggested to fall between the two values.

  19. Soil Moisture Mapping in an Arid Area Using a Land Unit Area (LUA Sampling Approach and Geostatistical Interpolation Techniques

    Directory of Open Access Journals (Sweden)

    Saeid Gharechelou

    2016-03-01

    Full Text Available Soil moisture (SM plays a key role in many environmental processes and has a high spatial and temporal variability. Collecting sample SM data through field surveys (e.g., for validation of remote sensing-derived products can be very expensive and time consuming if a study area is large, and producing accurate SM maps from the sample point data is a difficult task as well. In this study, geospatial processing techniques are used to combine several geo-environmental layers relevant to SM (soil, geology, rainfall, land cover, etc. into a land unit area (LUA map, which delineates regions with relatively homogeneous geological/geomorphological, land use/land cover, and climate characteristics. This LUA map is used to guide the collection of sample SM data in the field, and the field data is finally spatially interpolated to create a wall-to-wall map of SM in the study area (Garmsar, Iran. The main goal of this research is to create a SM map in an arid area, using a land unit area (LUA approach to obtain the most appropriate sample locations for collecting SM field data. Several environmental GIS layers, which have an impact on SM, were combined to generate a LUA map, and then field surveying was done in each class of the LUA map. A SM map was produced based on LUA, remote sensing data indexes, and spatial interpolation of the field survey sample data. The several interpolation methods (inverse distance weighting, kriging, and co-kriging were evaluated for generating SM maps from the sample data. The produced maps were compared to each other and validated using ground truth data. The results show that the LUA approach is a reasonable method to create the homogenous field to introduce a representative sample for field soil surveying. The geostatistical SM map achieved adequate accuracy; however, trend analysis and distribution of the soil sample point locations within the LUA types should be further investigated to achieve even better results. Co

  20. Modeling Soil Moisture in Support of the Revegetation of Military Lands in Arid Regions.

    Science.gov (United States)

    Caldwell, T. G.; McDonald, E. V.; Young, M. H.

    2003-12-01

    The National Training Center (NTC), the Army's primary mechanized maneuver training facility, covers approximately 2600 km2 within the Mojave Desert in southern California, and is the subject of ongoing studies to support the sustainability of military lands in desert environments. Revegetation of these lands by the Integrated Training Areas Management (ITAM) Program requires the identification of optimum growing conditions to reestablish desert vegetation from seed and seedling, especially with regard to the timing and abundance of plant-available water. Water content, soil water potential, and soil temperature were continuously monitored and used to calibrate the Simultaneous Heat And Water (SHAW) model at 3 re-seeded sites. Modeled irrigation scenarios were used to further evaluate the most effective volume, frequency, and timing of irrigation required to maximize revegetation success and minimize water use. Surface treatments including straw mulch, gravel mulch, soil tackifier and plastic sheet

  1. Policies, Land Use, and Water Resource Management in an Arid Oasis Ecosystem

    Science.gov (United States)

    Xue, Xian; Liao, Jie; Hsing, Youtian; Huang, Cuihua; Liu, Famin

    2015-05-01

    This paper addresses two questions concerning the relationship between state policies and environmental transformation in China in the past four decades. The first one deals with the promotion of agricultural productivity since the 1980s; the second, the water conservation measures as a response to the water crisis that peaked in the early 2000s. We had chosen Minqin County in northwestern China, one of the most fragile arid oasis systems in the world, as the study area. We found that the irrigated farmland in up and midstream areas had greatly expanded between the 1980s and the 2000s under the government policy of promoting commodity grain production. As a result, the runoff flowing into Minqin Oasis had reduced 80 % from the 1950s to early 2000s. Irrigated farmland in Minqin Oasis expanded 15.76 % from 1995 to 2000. In the 2000s, because of the changing policy discourse that has shifted from productivity to conservation, a new set of environmentally framed policies has restructured agricultural production in Minqin by 2005. These new policies included establishing a watershed-level water management system, promoting drought resistant crops, introducing water-saving irrigation measures, and forced reduction of irrigated farming acreage. These policies have produced positive results in terms of greater coverage of vegetation, rising ground water table, and reduction of evaporation. Nevertheless, new policies have also brought new challenges to both farmers and policy makers to keep the balance between poverty reduction and environmental sustainability in Minqin Oasis in the historically poor region in China's Northwest.

  2. Ecological soil quality affected by land use and management on semi-arid Crete

    Science.gov (United States)

    van Leeuwen, J. P.; Moraetis, D.; Lair, G. J.; Bloem, J.; Nikolaidis, N. P.; Hemerik, L.; de Ruiter, P. C.

    2015-03-01

    Land use and soil management practice can have strong effects on soil quality, defined in terms of soil fertility, carbon sequestration and conservation of biodiversity. In this study, we investigate whether ecological soil quality parameters are adequate to assess soil quality under harsh conditions, and are able to reflect different land uses and intensities of soil management practices. We selected three sites as main representatives for the dominant types of land use in the region: an intensively cultivated olive orchard (annually tilled), an extensively used olive orchard (not tilled) and a heavily grazed pasture site in the Koiliaris catchment (Crete/Greece). Soil quality was analysed using an ecosystem approach, studying soil biological properties such as soil organism biomass and activity, and taxonomic diversity of soil microarthropods, in connection to abiotic soil parameters, including soil organic matter contents, and soil aggregate stability. The intensively cultivated olive orchard had a much lower aggregate water stability than the extensive olive orchard and the pasture. Contents of soil organic C and N were higher in the extensively used olive orchard than in the intensively cultivated orchard, with intermediate concentrations in the pasture. This was mainly caused by the highest input of organic matter, combined with the lowest organic matter decomposition rate. Soil organism biomasses in all sites were relatively low compared to values reported from less harsh systems, while microarthropod richness was highest in the pasture compared to both the intensive and extensive olive orchards. From the present results we conclude that microarthropod taxonomic richness is a very useful indicator for ecological soil quality, because it is not only able to separate harsh sites from other systems, but it is also sensitive enough to show differences between land management practices under harsh conditions. Microbial biomass and especially microarthropod

  3. Habitat Fragmentation in Arid Zones: A Case Study of Linaria nigricans Under Land Use Changes (SE Spain)

    Science.gov (United States)

    Peñas, Julio; Benito, Blas; Lorite, Juan; Ballesteros, Miguel; Cañadas, Eva María; Martinez-Ortega, Montserrat

    2011-07-01

    Habitat fragmentation due to human activities is one of the most important causes of biodiversity loss. In Mediterranean areas the species have co-evolved with traditional farming, which has recently been replaced for more severe and aggressive practices. We use a methodological approach that enables the evaluation of the impact that agriculture and land use changes have for the conservation of sensitive species. As model species, we selected Linaria nigricans, a critically endangered plant from arid and semiarid ecosystems in south-eastern Spain. A chronosequence of the evolution of the suitable habitat for the species over more than 50 years has been reconstructed and several geometrical fragmentation indices have been calculated. A new index called fragmentation cadence (FC) is proposed to quantify the historical evolution of habitat fragmentation regardless of the habitat size. The application of this index has provided objective forecasting of the changes of each remnant population of L. nigricans. The results indicate that greenhouses and construction activities (mainly for tourist purposes) exert a strong impact on the populations of this endangered species. The habitat depletion showed peaks that constitute the destruction of 85% of the initial area in only 20 years for some populations of L. nigricans. According to the forecast established by the model, a rapid extinction could take place and some populations may disappear as early as the year 2030. Fragmentation-cadence analysis can help identify population units of primary concern for its conservation, by means of the adoption of improved management and regulatory measures.

  4. Survey of Revegetated Areas on the Fitzner/Eberhardt Arid Lands Ecology Reserve: Status and Initial Monitoring Results

    Energy Technology Data Exchange (ETDEWEB)

    Downs, Janelle L.; Link, Steven O.; Rozeboom, Latricia L.; Durham, Robin E.; Cruz, Rico O.; Mckee, Sadie A.

    2011-09-01

    During 2010, the U.S. Department of Energy (DOE), Richland Operations Office removed a number of facilities and debris from the Fitzner/Eberhardt Arid Lands Ecology Reserve (ALE), which is part of the Hanford Reach National Monument (HRNM). Revegetation of disturbed sites is necessary to stabilize the soil, reduce invasion of these areas by exotic weeds, and to accelerate re-establishment of native plant communities. Seven revegetation units were identified on ALE based on soils and potential native plant communities at the site. Native seed mixes and plant material were identified for each area based on the desired plant community. Revegetation of locations affected by decommissioning of buildings and debris removal was undertaken during the winter and early spring of 2010 and 2011, respectively. This report describes both the details of planting and seeding for each of the units, describes the sampling design for monitoring, and summarizes the data collected during the first year of monitoring. In general, the revegetation efforts were successful in establishing native bunchgrasses and shrubs on most of the sites within the 7 revegetation units. Invasion of the revegetation areas by exotic annual species was minimal for most sites, but was above initial criteria in 3 areas: the Hodges Well subunit of Unit 2, and Units 6 and 7.

  5. Performance and effects of land cover type on synthetic surface reflectance data and NDVI estimates for assessment and monitoring of semi-arid rangeland

    Science.gov (United States)

    Olexa, Edward M.; Lawrence, Rick L

    2014-01-01

    Federal land management agencies provide stewardship over much of the rangelands in the arid andsemi-arid western United States, but they often lack data of the proper spatiotemporal resolution andextent needed to assess range conditions and monitor trends. Recent advances in the blending of com-plementary, remotely sensed data could provide public lands managers with the needed information.We applied the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) to five Landsat TMand concurrent Terra MODIS scenes, and used pixel-based regression and difference image analyses toevaluate the quality of synthetic reflectance and NDVI products associated with semi-arid rangeland. Pre-dicted red reflectance data consistently demonstrated higher accuracy, less bias, and stronger correlationwith observed data than did analogous near-infrared (NIR) data. The accuracy of both bands tended todecline as the lag between base and prediction dates increased; however, mean absolute errors (MAE)were typically ≤10%. The quality of area-wide NDVI estimates was less consistent than either spectra lband, although the MAE of estimates predicted using early season base pairs were ≤10% throughout the growing season. Correlation between known and predicted NDVI values and agreement with the 1:1regression line tended to decline as the prediction lag increased. Further analyses of NDVI predictions,based on a 22 June base pair and stratified by land cover/land use (LCLU), revealed accurate estimates through the growing season; however, inter-class performance varied. This work demonstrates the successful application of the STARFM algorithm to semi-arid rangeland; however, we encourage evaluation of STARFM’s performance on a per product basis, stratified by LCLU, with attention given to the influence of base pair selection and the impact of the time lag.

  6. Screening Prosopis (mesquite) species for biofuel production on semi-arid lands. Final report, April 1, 1978-March 30, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P; Cannell, G H; Clark, P R; Osborn, J F; Nash, P

    1985-01-01

    Arid adapted nitrogen fixing trees and shrubs of the genus Prosopis (mesquite) have been examined for woody biomass production on semi-arid lands of southwestern United States. A germ-plasm collection of 900 accessions from North and South America and Africa was assembled. Field studies screening for biomass production, frost tolerance, response to irrigation, pod production and heat/drought tolerance involved a total of 80 accessions. Selections made from survivors of coal/frost screening trial had more frost tolerance and biomass productivity than prostrate selections from the ranges of Arizona, New Mexico and west Texas. Thirteen Prosopis species were found to nodulate, reduce acetylene to ethylene, and grow on a nitrogen free media in greenhouse experiments. The salinity tolerance of six Prosopis species was examined on a nitrogen free media in greenhouse experiments. No reduction in growth occurred for any species tested at a salinity of 6000 mg NaC1/L which is considered too saline for normal agricultural crops. Individual trees have grown 5 to 7 cm in basal diameter, and 2.0 to 3.7 meters in height per year and have achieved 50 kg oven dry weight per tree in 2 years with 600 mm water application per year. Vegetative propagation techniques have been developed and clones of these highly productive trees have been made. Small pilots on 1.5 x 1.5 m spacing in the California Imperial Valley had a first and second season dry matter production of 11.7 and 16.9 T/ha for P. chilensis (0009), 7.1 and 6.9 T/ha for P. glandulosa var. torreyana (0001), 9.8 and 19.2 T/ha for P. alba (0039) and 7.9 and 14.5 T/ha for progency of a California ornamental (0163). The projected harvested costs of $25.00 per oven dry ton or $1.50 per million Btu's compare favorable with coal and other alternative fuel sources in South Texas.

  7. Bacterial community structure and nitrogen transformation in hyporheic zones of arid-land streams

    Science.gov (United States)

    Zeglin, L. H.; Crenshaw, C. L.; Dahm, C. N.; Takacs-Vesbach, C.

    2007-12-01

    Hyporheic zones of desert streams can be areas of high biological activity and consequent nutrient transformation, particularly where land use change increases nutrient concentrations in a stream. Does hyporheic bacterial community composition vary, and does this biotic heterogeneity covary with water and nutrient supply? Bromide (Br-) and 15N-NO3- was injected for 24 hr in six streams (three "natural" reference streams, three streams in agricultural/urbanized catchments) in New Mexico and Arizona, USA. Four transects of 3 to 4 wells were placed along a longitudinal gradient within the study reach, and from these hyporheic water and gas samples were collected during and after each experiment. Gas samples were analyzed for O2, 15N2O, and 15N2. Hyporheic water samples were analyzed for major cations and anions, DOC, 15NO3- and 15NH4+. Bacterial diversity of hyporheic water was assessed using Denaturing Gradient Gel Electrophoresis (DGGE). There was high spatial and temporal variability in hyporheic bacterial community structure, connection with surface water and nutrient concentrations both within and among streams. For example, mean subsurface DGGE band richness per stream ranged from 9 to 21, and surface water comprised between 0 to 100 percent of hyporheic water in each well. There were strong differences in bacterial richness between streams (ANOVA, p nutrient concentration. 15NH4+ levels were higher in modified stream than reference stream subsurface waters, suggesting dissimilatory nitrate reduction to ammonium (DNRA) may be an important process in these hyporheic sediments. Our results to date suggest that though hyporheic microbial community structure is highly heterogeneous, this biological variability may be due to different factors than variability in stream nitrogen cycling function. Further work will identify dominant sequences within these bacterial communities and investigate within-stream heterogeneity.

  8. Evaluation of Land Surface Temperature Retrieval from FY-3B/VIRR Data in an Arid Area of Northwestern China

    Directory of Open Access Journals (Sweden)

    Jinxiong Jiang

    2015-05-01

    Full Text Available This paper uses the refined Generalized Split-Window (GSW algorithm to derive the land surface temperature (LST from the data acquired by the Visible and Infrared Radiometer on FengYun 3B (FY-3B/VIRR. The coefficients in the GSW algorithm corresponding to a series of overlapping ranges for the mean emissivity, the atmospheric Water Vapor Content (WVC, and the LST are derived using a statistical regression method from the numerical values simulated with an accurate atmospheric radiative transfer model MODTRAN 4 over a wide range of atmospheric and surface conditions. The GSW algorithm is applied to retrieve LST from FY-3B/VIRR data in an arid area in northwestern China. Three emissivity databases are used to evaluate the accuracy of different emissivity databases for LST retrieval, including the ASTER Global Emissivity Database (ASTER_GED at a 1-km spatial resolution (AG1km, an average of twelve ASTER emissivity data in the 2012 summer and emissivity spectra extracted from spectral libraries. The LSTs retrieved from the three emissivity databases are evaluated with ground-measured LST at four barren surface sites from June 2012 to December 2013 collected during the HiWATER field campaign. The results indicate that using emissivity extracted from ASTER_GED can achieve the highest accuracy with an average bias of 1.26 and −0.04 K and an average root mean square error (RMSE of 2.69 and 1.38 K for the four sites during daytime and nighttime, respectively. This result indicates that ASTER_GED is a useful emissivity database for generating global LST products from different thermal infrared data and that using FY-3B/VIRR data can produce reliable LST products for other research areas.

  9. Modelling ecogeomorphic feedbacks: investigating mechanisms of land degradation in semi-arid grassland and shrubland

    Science.gov (United States)

    Turnbull, Laura; Mueller, Eva; Tietjen, Britta; Wainwright, John

    2014-05-01

    Across vast areas of the world's drylands, land degradation is exacerbated by ecohydrological processes, which alter the structure, function and connectivity of dryland hillslopes. These processes are often interlinked through feedback mechanisms in such a way that a trigger may result in a re-organization of the affected landscape. Here, we present a spatially explicit process-based ecogeomorphic model, MAHLERAN-EcoHyD to enhance our understanding of complex linkages between abiotic and biotic drivers and processes of degradation in drylands. This ecogeomorphic modelling approach is innovative in two main ways: it couples biotic and abiotic processes, and simulates intra and inter-event dynamics, thus overcoming a key limitation of previous modelling approaches in terms of their temporal scaling, by simulating key ecogeomorphic processes at process-relevant time steps. Redistribution of water, sediment and nutrients during high-intensity rainstorms is simulated at 1-sec time steps, soil moisture and transpiration dynamics at daily time steps, and vegetation dynamics (establishment, growth, mortality) at 14-day time steps, over a high-resolution 1x1 m grid. We use this innovative modelling approach to investigate soil-vegetation feedback mechanisms within a grassland-shrubland transition zone at the Sevilleta Long Term Ecological Research site in the south-western United States. Results from three modelling experiments are presented: the first modelling experiment investigates the impact of annual variations in individual high-intensity storms to assess long-term variations in runoff, soil-moisture conditions and sediment and nutrient fluxes over two decades; the second modelling experiment assesses the impact of vegetation composition on spatial changes in surface soil texture due to soil erosion by water; and the third modelling experiment investigates how long-term changes in vegetation alter feedbacks between biotic and abiotic processes using scenarios for

  10. Water, land, climate change and agrarian livelihood in an arid region riparian corridor: Rayón, Sonora, Mexico

    Science.gov (United States)

    Lee, R.; Scott, C. A.; Curl, K.; House-Peters, L.; Buechler, S.

    2012-12-01

    Results of recent fieldwork in Rayón, Sonora, Mexico (funded by NSF's "Strengthening Resilience of Arid Region Riparian Corridors") indicate that the coupled natural and human (CNH) system that has persisted since the town's founding in 1626 is being degraded and destabilised by a confluence of social and ecological pressures. System change or loss of key system services and products has important implications for ecological services and human economic activity in the riparian corridor. Less water quantity is the primary factor responsible for driving system degradation and change. Drought caused by climate change is widely perceived by agriculturists as responsible for reduced water quantity in the riparian area. Reductions in water quantity are so severe that the once perennial Rio San Miguel did not run during 2012's summer months for the first time in residents' memory. Ninety-percent of wells are dry. Fields irrigated by surface-water acequias were not planted. Starvation or dehydration has thinned herd sizes. Residents fear they will lose the ability to practice their traditional livelihoods: ranching, farming and cheese production. Drought conditions and resource management in response to climatic change have had a net negative impact on ecological services. Agriculturists have responded to less forage and pasture for cattle by clearing mesquite forests, putting land into production, and increasing water demand. From interviews it appears this process is cyclical: agriculturists widely believe access to more water or an end to the drought are the only ways to improve conditions. Interviews also reveal (a) agriculturists view technology, especially that which is able to improve water-use efficiency, as means to reduce stress in the CNH system and (b) a holistic view that couples natural well-being to human well-being is absent from the majority of respondents' worldviews. Technological and adoption of holistic perceptions are adaptations that may potentially

  11. The dominant role of semi-arid ecosystems in the trend and variability of the land CO2 sink

    DEFF Research Database (Denmark)

    Ahlström, Anders; Raupach, Michael R.; Schurgers, Guy;

    2015-01-01

    The growth rate of atmospheric carbon dioxide (CO2) concentrations since industrialization is characterized by large interannual variability, mostly resulting from variability in CO2 uptake by terrestrial ecosystems (typically termed carbon sink). However, the contributions of regional ecosystems...... regions. Whereas the mean sink is dominated by highly productive lands (mainly tropical forests), the trend and interannual variability of the sink are dominated by semi-arid ecosystems whose carbon balance is strongly associated with circulation-driven variations in both precipitation and temperature....

  12. Determination of unit nutrient loads for different land uses in wet periods through modelling and optimization for a semi-arid region

    Science.gov (United States)

    Özcan, Zeynep; Kentel, Elçin; Alp, Emre

    2016-09-01

    Diffuse pollution abatement has been a challenge for decision-makers because of the intermittent nature and difficulty of identifying impacts of non-point sources. Depending on the degree of complexity of the system processes and constraints related to time, budget and human resources, variety of tools are used in diffuse pollution management. Decision-makers prefer to use rough estimates that require limited time and budget, in the preliminary assessment of diffuse pollution. The unit pollution load method which is based on the pollution generation rate per unit area and time for a given land use can aid decision-makers in the preliminary assessment of diffuse pollution. In this study, a deterministic distributed watershed model, SWAT is used together with nonlinear optimization models to estimate unit nutrient pollution loads during wet periods for different land use classes for the semi-arid Lake Mogan watershed that is dominated by agricultural activities. Extensive data sets including in-stream water quality and flowrate measurements, meteorological data, land use/land cover (LULC) map developed using remote sensing algorithms, information about agricultural activities, and soil data are used to calibrate and verify the hydraulic and water quality components of SWAT model. Results show that the unit total nitrogen (TN) and total phosphorus (TP) loads (0.46 kg TN/ha/yr and 0.07 kg TP/ha/yr) generated from the watershed during wet periods are very close to the minimum values of the loads specified in the literature and highly depend on the variations in rainfall. Estimated unit nutrient loads both at watershed scale and for different land use classes can be used to assess diffuse pollution control measures for similar regions with semi-arid conditions and heavy agricultural activity.

  13. Remote Sensing Parameterization of Land Surface Heat Fluxes over Arid and Semi-arid Areas%干旱及半干旱地区地表能量通量的卫星遥感参数化

    Institute of Scientific and Technical Information of China (English)

    马耀明; 王介民; 黄荣辉; 卫国安; Massimo Menenti; 苏中波; 胡泽勇; 高峰; 文军

    2003-01-01

    对干旱及半干旱地区非均匀地表区域地表能量通量的研究是一个十分重要但又是一个难点问题.作者提出了一个基于卫星遥感和地面观测的参数化方案,并把其用于中国西北地区"我国重大气候和天气灾害形成和预测理论的研究"(国家重点基础研究发展规划项目G1998040900,1999-2003)的"敦煌试验"区和"黑河试验"(HEIFE,1989-1994)区,并利用4个景("敦煌试验区":2000年6月3日-初夏、2000年8月22日-夏末和2001年1月29日-冬天;"黑河试验"区:1991年7月9日-夏季)的陆地资源卫星Landsat-5 TM和Landsat-7 TM资料进行了分析研究,得到了有关干旱及半干旱地区非均匀地表区域地表特征参数、植被参数和地表能量通量的分布图像.最后还讨论了参数化方案的适用范围和需改进之处.%Dealing with the regional land surfaces heat fluxes over inhomogeneous land surfaces in arid and semi-arid areas is an important but not an easy issue. In this study, one parameterization method based onsatellite remote sensing and field observations is proposed and tested for deriving the regional land surfaceheat fluxes over inhomogeneous landscapes. As a case study, the method is applied to the Dunhuangexperimental area and the HEIFE (Heihe River Field Experiment, 1988-1994) area. The Dunhuang areais selected as a basic experimental area for the Chinese National Key Programme for Developing BasicSciences: Research on the Formation Mechanism and Prediction Theory of Severe Climate Disaster inChina (G1998040900, 1999-2003). The four scenes of Landsat TM data used in this study are 3 June 2000,22 August 2000, and 29 01- 2001 for the Dunhuang area and 9 07- 1991 for the HEIFE area. Theregional distributions of land surface variables, vegetation variables, and heat fluxes over inhomogeneouslandscapes in arid and semi-arid areas are obtained in this study.

  14. Rainfed agriculture in a semi-arid tropical climate. Aspects of land- and water management for red soils in India

    NARCIS (Netherlands)

    Huibers, F.P.

    1985-01-01

    Rainfed agriculture is defined as the production of field crops that completely depend on the local precipitation for their water supply. Although in the semi-arid tropics the mean annual precipitation might seem to be sufficient to grow (adapted) crops, its variability over the years and its errati

  15. Estimation of evapotranspiration for different land covers in a Brazilian semi-arid region: A case study of the Brígida River basin, Brazil

    Science.gov (United States)

    Santos, Celso Augusto Guimarães; Silva, Richarde Marques da; Silva, Alexandro Medeiros; Brasil Neto, Reginaldo Moura

    2017-03-01

    In this study, the Surface Energy Balance Algorithm for Land (SEBAL) was used to compute the surface albedo, vegetation indices (NDVI, SAVI and LAI), surface temperature, soil heat flux and evapotranspiration (ET) over two contrasting years (dry and wet) in the Brígida River basin, a semi-arid region of north-eastern Brazil. The actual ET was computed during satellite overpass and was integrated for 24 h on a pixel-by-pixel basis for the daily ET distribution. Due to the topographic effects, an attempt was also made to incorporate DEM information to estimate the net radiation. The land cover types identified in the watershed are cropland, bare land, dense canopy, grassland, and caatinga vegetation. In order to study the variation among the biophysical parameters and ET, two-way analysis of variance (ANOVA) was used. The ET calculated by SEBAL ranged between 2.46 and 6.87 mm/day for the dry year (1990) and 1.31 and 6.84 mm/day for the wet year (2009) for the river basin. The results showed that a reduction in vegetation cover is evident in the temporal and spatial analysis over the studied periods in the region and that these facts influence the values of the energy balance and ET. The results showed significant differences in the variables of land cover type and year at the probability level of 0.05 for all land cover types.

  16. Fractal Characteristics of Soil under Different Land-Use Patterns in the Arid and Semi-Arid Region of the Western Tibet Plateau, China

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-dan; LIU Shu-zhen; LIU Gang-cai

    2005-01-01

    The fractal geometry to the study of soil structure, its dynamics, and physical processes appears to be a useful tool in reaching a better understanding of system performance. This research was designed to apply fractal models for mass into computing Dp and Da values. As a result, the relationships among land use methods, fractal dimension and soil fertility have been discussed. The study conclusions include that (i) fractal dimension indicates not only characteristics of soil texture but also effects of natural environment changes and human activities on soil properties, (ii) soil fertility is best when Dp <2.65 and Da <2.44, (iii) maximal values of Dp under all land use patterns are equal and appear in the range the depth of 15-20 cm in the study area, but maximal values of Da are different and distribute in various profile depth. These results can provide an important support to understand soil properties in plateau soil-forming environment, and be helpful to conduct scientific soil tillage and management.

  17. Land use change and its effects on water quality in typical inland lake of arid area in China.

    Science.gov (United States)

    Cui, Hong; Zhou, Xiaode; Guo, Mengjing; Wei, Wu

    2016-07-01

    Land-use change is very important for determining and assessing the influence of human activity on aquatic environment of rivers and lakes. The present work with Bosten River basin as the subject, analyzes features of dynamic land-use change of the basin from 1993 to 2013, in order to study the influence of land-use pattern change on the basin water quality, according to the land-use/land-cover(LUCC) chart from 2000 to 2013 made by ArcGIS and ENVI. It shows cultivated land, wetland and forestland constitute most of Bosten River basin, taking up over 41.7% of the total; from 1993-2000, LUCC of the basin is relatively small, with an increase of cultivated land, residential-industry land, water wetlands by 15.09%-18.33%,most of which are transformed from forestland, grassland and unused land; from 2000-2013, LUCC of the basin is relatively significant, with a continuing and bigger increase of cultivated land and Residential-industry area, most of which are transformed from water wetlands and unused land. Based on analysis of landuse pattern and water quality index, it can be told that water pollution is positively correlated to cultivated land and residential-industry area and negatively correlated to water and grassland. Also, the influence of land-use pattern change on water quality has been discussed, whose finding can serve as the scientific evidence for land-use optimization and water pollution control.

  18. Assessing the biophysical and socio-economic potential of Sustainable Land Management and Water Harvesting Technologies for rainfed agriculture across semi-arid Africa.

    Science.gov (United States)

    Irvine, Brian; Fleskens, Luuk; Kirkby, Mike

    2016-04-01

    Stakeholders in recent EU projects identified soil erosion as the most frequent driver of land degradation in semi-arid environments. In a number of sites, historic land management and rainfall variability are recognised as contributing to the serious environmental impact. In order to consider the potential of sustainable land management and water harvesting techniques stakeholders and study sites from the projects selected and trialled both local technologies and promising technologies reported from other sites . The combined PESERA and DESMICE modelling approach considered the regional effects of the technologies in combating desertification both in environmental and socio-economical terms. Initial analysis was based on long term average climate data with the model run to equilibrium. Current analysis, primarily based on the WAHARA study sites considers rainfall variability more explicitly in time series mode. The PESERA-DESMICE approach considers the difference between a baseline scenario and a (water harvesting) technology scenario, typically, in terms of productivity, financial viability and scope for reducing erosion risk. A series of 50 year rainfall realisations are generated from observed data to capture a full range of the climatic variability. Each realisation provides a unique time-series of rainfall and through modelling can provide a simulated time-series of crop yield and erosion risk for both baseline conditions and technology scenarios. Subsequent realisations and model simulations add to an envelope of the potential crop yield and cost-benefit relations. The development of such envelopes helps express the agricultural and erosional risk associated with climate variability and the potential for conservation measures to absorb the risk, highlighting the probability of achieving a given crop yield or erosion limit. Information that can directly inform or influence the local adoption of conservation measures under the climatic variability in semi-arid

  19. Land Cover Land Use Change and Soil Organic Carbon under Climate Variability in the Semi-Arid West African Sahel (1960-2050)

    Science.gov (United States)

    Dieye, Amadou M.

    2016-01-01

    Land Cover Land Use (LCLU) change affects land surface processes recognized to influence climate change at local, national and global levels. Soil organic carbon is a key component for the functioning of agro-ecosystems and has a direct effect on the physical, chemical and biological characteristics of the soil. The capacity to model and project…

  20. Changes of soil bacterial diversity as a consequence of agricultural land use in a semi-arid ecosystem.

    Directory of Open Access Journals (Sweden)

    Guo-Chun Ding

    Full Text Available Natural scrublands in semi-arid deserts are increasingly being converted into fields. This results in losses of characteristic flora and fauna, and may also affect microbial diversity. In the present study, the long-term effect (50 years of such a transition on soil bacterial communities was explored at two sites typical of semi-arid deserts. Comparisons were made between soil samples from alfalfa fields and the adjacent scrublands by two complementary methods based on 16S rRNA gene fragments amplified from total community DNA. Denaturing gradient gel electrophoresis (DGGE analyses revealed significant effects of the transition on community composition of Bacteria, Actinobacteria, Alpha- and Betaproteobacteria at both sites. PhyloChip hybridization analysis uncovered that the transition negatively affected taxa such as Acidobacteria, Chloroflexi, Acidimicrobiales, Rubrobacterales, Deltaproteobacteria and Clostridia, while Alpha-, Beta- and Gammaproteobacteria, Bacteroidetes and Actinobacteria increased in abundance. Redundancy analysis suggested that the community composition of phyla responding to agricultural use (except for Spirochaetes correlated with soil parameters that were significantly different between the agricultural and scrubland soil. The arable soils were lower in organic matter and phosphate concentration, and higher in salinity. The variation in the bacterial community composition was higher in soils from scrubland than from agriculture, as revealed by DGGE and PhyloChip analyses, suggesting reduced beta diversity due to agricultural practices. The long-term use for agriculture resulted in profound changes in the bacterial community and physicochemical characteristics of former scrublands, which may irreversibly affect the natural soil ecosystem.

  1. Relation between seasonally detrended shortwave infrared reflectance data and land surface moisture in semi-arid Sahel

    DEFF Research Database (Denmark)

    Olsen, Jørgen Lundegaard; Ceccato, Pietro; Proud, Simon Richard;

    2013-01-01

    In the Sudano-Sahelian areas of Africa droughts can have serious impacts on natural resources, and therefore land surface moisture is an important factor. Insufficient conventional sites for monitoring land surface moisture make the use of Earth Observation data for this purpose a key issue...

  2. Development of Novel Water-extraction System with Thermoelectric Module Using Solar and Wind Power in Arid Land

    Institute of Scientific and Technical Information of China (English)

    HAYASHI Tsutomu; TAGAWA Kotaro; TANAKA Kenji; MORITA Yasunari

    2010-01-01

    This study aimed to develop a water-extraction system which could produce the fresh water from the air in arid regions and which used renewable energies as the electric power source. In this paper, the experiments for water extraction from the air were carried out by using the novel multi-stage water-extraction device with Peltier deices for two cases of temperature and related humidity of the air. One was the case where the temperature and the related humidity of the air were constant, and the other was the case where they were simulated the variation of the temperature and related humidity of the air in a day of summer and spring in Loess Plateau, China. The effects of the temperature and related humidity of the atmospheric air and supply the electric power to Peltier devices on performance of water production of the device were investigated and reported.

  3. Revegetation Plan for Areas of the Fitzner-Eberhardt Arid Lands Ecology Reserve Affected by Decommissioning of Buildings and Infrastructure and Debris Clean-up Actions

    Energy Technology Data Exchange (ETDEWEB)

    Downs, Janelle L.; Durham, Robin E.; Larson, Kyle B.

    2011-01-01

    The U.S. Department of Energy (DOE), Richland Operations Office is working to remove a number of facilities on the Fitzner Eberhardt Arid Lands Ecology Reserve (ALE), which is part of the Hanford Reach National Monument. Decommissioning and removal of buildings and debris on ALE will leave bare soils and excavated areas that need to be revegetated to prevent erosion and weed invasion. Four main areas within ALE are affected by these activities (DOE 2009;DOE/EA-1660F): 1) facilities along the ridgeline of Rattlesnake Mountain, 2) the former Nike missile base and ALE HQ laboratory buildings, 3) the aquatic research laboratory at Rattlesnake Springs area, and 4) a number of small sites across ALE where various types of debris remain from previous uses. This revegetation plan addresses the revegetation and restoration of those land areas disturbed by decommissioning and removal of buildings, facilities and associated infrastructure or debris removal. The primary objective of the revegetation efforts on ALE is to establish native vegetation at each of the sites that will enhance and accelerate the recovery of the native plant community that naturally persists at that location. Revegetation is intended to meet the direction specified by the Environmental Assessment (DOE 2009; DOE/EA-1660F) and by Stipulation C.7 of the Memorandum of Agreement (MOA) for the Rattlesnake Mountain Combined Community Communication Facility and InfrastructureCleanup on the Fitzner/Eberhardt Arid Lands Ecology Reserve, Hanford Site, Richland Washington(DOE 2009; Appendix B). Pacific Northwest National Laboratory (PNNL) under contract with CH2M Hill Plateau Remediation Company (CPRC) and in consultation with the tribes and DOE-RL developed a site-specific strategy for each of the revegetation units identified within this document. The strategy and implementation approach for each revegetation unit identifies an appropriate native species mix and outlines the necessary site preparation activities

  4. Detecting new Buffel grass infestations in Australian arid lands: evaluation of methods using high-resolution multispectral imagery and aerial photography.

    Science.gov (United States)

    Marshall, V M; Lewis, M M; Ostendorf, B

    2014-03-01

    We assess the feasibility of using airborne imagery for Buffel grass detection in Australian arid lands and evaluate four commonly used image classification techniques (visual estimate, manual digitisation, unsupervised classification and normalised difference vegetation index (NDVI) thresholding) for their suitability to this purpose. Colour digital aerial photography captured at approximately 5 cm of ground sample distance (GSD) and four-band (visible–near-infrared) multispectral imagery (25 cm GSD) were acquired (14 February 2012) across overlapping subsets of our study site. In the field, Buffel grass projected cover estimates were collected for quadrates (10 m diameter), which were subsequently used to evaluate the four image classification techniques. Buffel grass was found to be widespread throughout our study site; it was particularly prevalent in riparian land systems and alluvial plains. On hill slopes, Buffel grass was often present in depressions, valleys and crevices of rock outcrops, but the spread appeared to be dependent on soil type and vegetation communities. Visual cover estimates performed best (r 2 0.39), and pixel-based classifiers (unsupervised classification and NDVI thresholding) performed worst (r 2 0.21). Manual digitising consistently underrepresented Buffel grass cover compared with field- and image-based visual cover estimates; we did not find the labours of digitising rewarding. Our recommendation for regional documentation of new infestation of Buffel grass is to acquire ultra-high-resolution aerial photography and have a trained observer score cover against visual standards and use the scored sites to interpolate density across the region.

  5. Small-Scale Vertical Distribution of Bacterial Biomass and Diversity in Biological Soil Crusts from Arid Lands in the Colorado Plateau

    Science.gov (United States)

    Garcia-Pichel, F.; Johnson, S.L.; Youngkin, D.; Belnap, J.

    2003-01-01

    We characterized, at millimeter resolution, bacterial biomass, diversity, and vertical stratification of biological soil crusts in arid lands from the Colorado Plateau. Microscopic counts, extractable DNA, and plate counts of viable aerobic copiotrophs (VAC) revealed that the top centimeter of crusted soils contained atypically large bacterial populations, tenfold larger than those in uncrusted, deeper soils. The plate counts were not always consistent with more direct estimates of microbial biomass. Bacterial populations peaked at the immediate subsurface (1-2 mm) in light-appearing, young crusts, and at the surface (0-1 mm) in well-developed, dark crusts, which corresponds to the location of cyanobacterial populations. Bacterial abundance decreased with depth below these horizons. Spatially resolved DGGE fingerprints of Bacterial 16S rRNA genes demonstrated the presence of highly diverse natural communities, but we could detect neither trends with depth in bacterial richness or diversity, nor a difference in diversity indices between crust types. Fingerprints, however, revealed the presence of marked stratification in the structure of the microbial communities, probably a result of vertical gradients in physicochemical parameters. Sequencing and phylogenetic analyses indicated that most of the naturally occurring bacteria are novel types, with low sequence similarity (83-93%) to those available in public databases. DGGE analyses of the VAC populations indicated communities of lower diversity, with most types having sequences more than 94% similar to those in public databases. Our study indicates that soil crusts represent small-scale mantles of fertility in arid ecosystems, harboring vertically structured, little-known bacterial populations that are not well represented by standard cultivation methods.

  6. Integrated approach for the assessment and development of groundwater resources in arid lands: Applications in the Quetta Valley, Pakistan

    Science.gov (United States)

    Sagintayev, Zhanay (Jay Sagin)

    106 m3/year up to 432 x 106 m3/year and achieve sustainable extraction. The adopted methodologies are not a substitute for traditional approaches that require extensive field datasets, but they could provide first-order estimates for rainfall, runoff, and recharge in the arid and semi-arid parts of the world that are inaccessible and/or lack adequate coverage with stream flow and precipitation data.

  7. Changes in seed dispersal processes and the potential for between-patch connectivity for an arid land daisy.

    Science.gov (United States)

    Emmerson, Louise M; Facelli, José M; Chesson, Peter; Possingham, Hugh; Day, Jemery R

    2012-03-01

    Dispersal is a major and critical process in population biology that has been particularly challenging to study. Animals can have major roles in seed dispersal even in species that do not appear specifically adapted to animal-aided dispersal. This can occur by two processes: direct movement of diaspores by animals and modification of landscape characteristics by animals in ways that greatly influence dispersal. We exploited the production of large, persistent dispersal structures (seed heads, henceforth) by Erodiophyllum elderi (Asteraceae), a daisy from arid Australia, to further understand secondary dispersal. Seed head dispersal on and off animal tracks in eight E. elderi patches was monitored for 9.5 months by periodically recording the location of marked seed heads. Sites were located inside a reserve that excludes sheep but not kangaroos, and in a nearby area with both kangaroos and sheep. The distance moved and likelihood of seed head movement was higher in areas with sheep, and especially along animal tracks. There was clear evidence that seed heads were channeled down animal tracks during large rainfall events. Seed head dispersal away from patches occurred to a limited extent via their physical contact with sheep and potentially via wind dispersal. Thus, the advantages of this study system allowed us to demonstrate the two postulated effects of herbivores on dispersal via direct movement of seed heads, and two distinct indirect effects through landscape modification by herbivores from the creation of animal tracks and the denudation of vegetation.

  8. Employing native shrubs to improve agricultural potential of arid lands: Drawing on plants to draw water (Invited)

    Science.gov (United States)

    Dragila, M. I.; Kizito, F.; Dick, R.

    2009-12-01

    Even though soil moisture poses limits on landscape dynamics, plant communities within the landscape can also regulate the spatial distribution of moisture, thus creating a biofeedback system that advances the system towards a specific landscape order. This behavior is evident in arid climates where specific parameters, such as soil moisture, are close to sustainability limits and result in a distinct spatial distribution of plant communities. Understanding plant-soil water relationships can lead to management tools to improve landscape function. Plant-soil interactions that influence soil moisture include, local changes in soil texture when plants trap airborne soil particles, increases in organic matter content below their foliage, and root distribution. We specifically focus on a process commonly referred to as hydraulic redistribution wherein plant roots draw moisture vertically to the near surface, raising the potential for seed germination and maintenance through short drought periods. Two fieldwork sites in Senegal were used to investigate the role of native shrubs in controlling soil moisture movement, and in particular, using these native plants to enhance agricultural potential.

  9. Utilisation of priority traditional medicinal plants and local people's knowledge on their conservation status in arid lands of Kenya (Mwingi District

    Directory of Open Access Journals (Sweden)

    Njoroge Grace N

    2010-08-01

    Full Text Available Abstract Mwingi District lies within the Kenyan Arid and Semiarid lands (ASALs in Eastern Province. Although some ethnobotanical surveys have been undertaken in some arid and semiarid areas of Kenya, limited studies have documented priority medicinal plants as well as local people's awareness of conservation needs of these plants. This study sought to establish the priority traditional medicinal plants used for human, livestock healthcare, and those used for protecting stored grains against pest infestation in Mwingi district. Further, the status of knowledge among the local people on the threat and conservation status of important medicinal species was documented. This study identified 18 species which were regarded as priority traditional medicinal plants for human health. In terms of priority, 8 were classified as moderate, 6 high, while 4 were ranked highest priority species. These four species are Albizia amara (Roxb. Boiv. (Mimosacaeae, Aloe secundiflora (Engl. (Aloaceae, Acalypha fruticosa Forssk. (Euphorbiaceae and Salvadora persica L. (Salvadoraceae. In regard to medicinal plants used for ethnoveterinary purposes, eleven species were identified while seven species were reported as being important for obtaining natural products or concoctions used for stored grain preservation especially against weevils. The data obtained revealed that there were new records of priority medicinal plants which had not been documented as priority species in the past. Results on conservation status of these plants showed that more than 80% of the respondents were unaware that wild medicinal plants were declining, and, consequently, few of them have any domesticated species. Some of the species that have been conserved on farm or deliberately allowed to persist when wild habitats are converted into agricultural lands include: Croton megalocarpus Hutch., Aloe secundiflora, Azadirachta indica A. Juss., Warburgia ugandensis Sprague, Ricinus communis L. and

  10. Modelling nutrient dynamics during runoff events over a trajectory of land degradation from semi-arid grassland to shrubland in the south-western USA

    Science.gov (United States)

    Brazier, R. E.; Turnbull, L.; Wainwright, J.

    2009-04-01

    Land degradation in arid and semi-arid areas, such as the invasion of grasslands by shrubs, is often associated with an increase in runoff and erosion and a change in nutrient dynamics. Modelling of nutrient dynamics during runoff events (in particular particulate-bound nutrients), is particularly important, since the spatial redistribution of nutrients (in addition to water and sediment) can have significant implications for vegetation dynamics in these ecosystems. In this study, MAHLERAN (Model for Assessing Hillslope to Landscape Runoff, Erosion and Nutrients) is extensively evaluated against runoff and erosion data from four plots (representative of different stages of land degradation) over a transition from grassland to shrubland at the Sevilleta National Wildlife Refuge in New Mexico, USA. MAHLERAN already simulates dissolved nutrient dynamics (based on an advection-dispersion model of N and P). A new particulate-bound nutrient module was developed to include a representation of particulate-bound nutrient dynamics which is an important form of nutrient transport in these ecosystems. Understanding dynamics of both dissolved and particulate-bound nutrient dynamics during runoff events is imperative, because of their differing roles in terms of nutrient bioavailability and potential implications for plant dynamics. MAHLERAN was evaluated against runoff, erosion and nutrient data that was collected from the four plots over the transition from grassland to shrubland. Results of the model evaluation show that the runoff and erosion components of MAHLERAN perform well, as does the new particulate-bound nutrient submodel. However, since the particulate-bound nutrient submodel is effectively a bolt-on to the erosion model, the performance of the particulate-bound nutrient model is dependent on the performance of the erosion component of MAHLERAN. The performance of the dissolved nutrient component of MAHLERAN was abysmal, which indicates that the process

  11. Land cover change detection based on satellite data for an arid area to the south of Aksu in Taklimakan desert

    Institute of Scientific and Technical Information of China (English)

    Kiyoshi; TSUCHIYA; Tamotsu; IGARSHI; Muhtar; QONG

    2010-01-01

    An experiment is made to detect the land-cover change in the area located to the south of Aksu in the northern Taklimakan desert through analyses of satellite data pixel by pixel basis. The analyzed data are those observed in the late summer and early autumn of 1973, 1977, 1993 and 1995. As a parameter of land-cover, SAVI (Soil Adjusted Vegetation Index) derived from the data of Landsat MSS and JERS-1 OPS (Optical Sensor) is used. The result indicates the increase of vegetation in the oasis areas, confluent area of the Yarkant and Kashgar Rivers and around reservoirs while little change occurs in the desert area. The 1973 satellite image shows the abundant flow in the Yarkant River while the river is almost dried up in the satellite images of later years. The trend of the decrease in the Hotan River flow is recognized although not so dramatic as that of the Yarkant River.

  12. Atmospheric reactive nitrogen concentrations at ten sites with contrasting land use in an arid region of Central Asia

    Directory of Open Access Journals (Sweden)

    K. H. Li

    2012-06-01

    Full Text Available Atmospheric concentrations of reactive nitrogen species (Nr from 2009 to 2011 are reported for ten sites in Xinjiang, an arid region in Northwest China. Concentrations of NH3, NO2, particulate ammonium and nitrate (pNH4+ and pNO3 showed large spatial and seasonal variation and averaged 7.71, 9.68, 1.81 and 1.13 μg N m−3, and PM10 concentrations averaged 249.2 μg m−3 across all sites. Lower NH3 concentrations and higher NO2, pNH4+ and pNO3 concentrations were found in winter, reflecting serious air pollution due to domestic heating in winter and other anthropogenic sources such as increased emissions from motor traffic and industry. The order of increasing total concentrations of Nr species was alpine grassland < desert, desert-oasis ecotone < desert in an oasis < farmland < suburban and urban ecosystems. Lower ratios of secondary particles (NH4+ and NO3 were found in the desert and desert-oasis ecotone, while urban and suburban areas had higher ratios, which implies that anthropogenic activities have greatly influenced local air quality and must be controlled.

  13. Quality and fatty acid profile of the milk of indigenous goats subjected to different local diets in Tunisian arid lands.

    Science.gov (United States)

    Ayeb, N; Addis, M; Fiori, M; Khorchani, S; Atigui, M; Khorchani, T

    2016-02-01

    The study tested the hypothesis that certain pastoral forages and olive by-products, available in arid areas, may positively influence fatty acid composition and physicochemical properties of goat's milk. Thirty indigenous goats (body weight = 25.2 kg; age = 4.1 years) were allocated to three groups. During 60 days, the goats received ad libitum either dried olive leaves + Stipa tenacissima (group OL), khortane grass hay (group Ko) or oat hay (control diet, group OH). Milk samples were collected and analysed for total solids, fat, protein, lactose and ash content and fatty acid profile. Average milk yield did not statistically differ among groups. Milk total solids from OL group were higher in comparison with Ko and C groups (15.3, 14.7 and 14.5%, respectively; p < 0.05). Fat content was also higher for the OL group as compared to the other groups (5.44 vs. 5.01 and 4.66%, respectively, for Ko and OH). No significant differences were observed for the milk content of lactose, protein and ash. The percentage of saturated fatty acids of total milk fat was higher in OL and Ko groups compared to the C group (p < 0.001); the milk whereof was characterized by the highest percentage of monounsaturated (p < 0.01) and total unsaturated fatty acids. Milk fat of Ko and C groups showed significantly higher proportions of rumenic (CLA cis-9 trans-11) and vaccenic acids (C18:1 trans-11) compared to OL milk. The feeding system based on Stipa tenacissima and dried olive leaves resulted in the milk lowest proportion of trans-fatty acids and the highest proportion of polyunsaturated ω3-fatty acids (p < 0.05).

  14. Using remotely sensed data to estimate area-averaged daily surface fluxes over a semi-arid mixed agricultural land

    OpenAIRE

    2008-01-01

    Optical remote sensing has been widely used for diagnostics of land surface atmosphere exchanges, including evapotranspiration (ET). Estimating ET now benefits from modeling maturity at local scale, while ongoing challenges include both spatial and temporal issues: influences of spatial heterogeneities on non-linear behavior when upscaling and extrapolation of instantaneous estimates at satellite overpass to the daily scale. Both issues are very important when using remote sensing for managin...

  15. Evaluating the effect of land use land cover change in a rapidly urbanizing semi-arid watershed on estuarine freshwater inflows

    Science.gov (United States)

    Sahoo, D.; Smith, P.; Popescu, S.

    2006-12-01

    Estuarine freshwater inflows along with their associated nutrient and metal delivery are influenced by the land use/land cover (LULC) and water management practices in the contributing watershed. This study evaluates the effect of rapid urbanization in the San Antonio River Watershed on the amount of freshwater inflow reaching the San Antonio-Guadalupe estuary on the Gulf Coast of Texas. Remotely sensed data from satellite imagery provided a source of reliable data for land use classification and land cover change analysis; while long time series of the geophysical signals of stream flow and precipitation provided the data needed to assess change in flow in the watershed. LULC was determined using LANDSAT (5 TM and 7 ETM) satellite images over 20 years (1985-2003). The LANDSAT images were classified using an ENVI. ISODATA classification scheme. Changes were quantified in terms of the urban expansion that had occurred in past 20 years using an urban index. Streamflow was analyzed using 20 years (1985-2004) of average daily discharge obtained from the USGS gauging station (08188500) closest to the headwaters of the estuary. Baseflow and storm flow were partitioned from total flow using a universally used baseflow separation technique. Precipitation data was obtained from an NCDC station in the watershed. Preliminary results indicate that the most significant change in land use over the 20 year period was an increase in the total amount of impervious area in the watershed. This increase in impervious area was accompanied by an increase in both total streamflow and in baseflow over the same period. The investigation did not show a significant change in total annual precipitation from 1990 to 2004. This suggests that the increase in streamflow was more influenced by LULC than climate change. One explanation for the increase in baseflow may be an increase in return flows resulting from an increase in the total number of wastewater treatment plants in the watershed.

  16. Biological soil crusts: An organizing principle in dryland ecosystems (aka: the role of biocrusts in arid land hydrology)

    Science.gov (United States)

    Chamizo, Sonia; Belnap, Jayne; Elridge, David J; Issa, Oumarou M

    2016-01-01

    Biocrusts exert a strong influence on hydrological processes in drylands by modifying numerous soil properties that affect water retention and movement in soils. Yet, their role in these processes is not clearly understood due to the large number of factors that act simultaneously and can mask the biocrust effect. The influence of biocrusts on soil hydrology depends on biocrust intrinsic characteristics such as cover, composition, and external morphology, which differ greatly among climate regimes, but also on external factors as soil type, topography and vegetation distribution patterns, as well as interactions among these factors. This chapter reviews the most recent literature published on the role of biocrusts in infiltration and runoff, soil moisture, evaporation and non-rainfall water inputs (fog, dew, water absorption), in an attempt to elucidate the key factors that explain how biocrusts affect land hydrology. In addition to the crust type and site characteristics, recent studies point to the crucial importance of the type of rainfall and the spatial scale at which biocrust effects are analyzed to understand their role in hydrological processes. Future studies need to consider the temporal and spatial scale investigated to obtain more accurate generalizations on the role of biocrusts in land hydrology.

  17. Non-timber forest product (NTFP) extraction in arid environments: Land-use change, frankincense production and the sustainability of Boswellia sacra in Dhofar (Oman)

    Science.gov (United States)

    Farah, Mohamud Haji

    Frankincense, a much revered non-timber forest product (NTFP) known as luban in Oman, is a gum-resin extracted from Boswellia sacra (meqerot). In Oman, B. sacra is endemic to ecological zones in and around Dhofar's southern mountain ranges of Jabal Samhan, Jabal Qamar and Jabal Qara. Hojar (Samhan Nejd), Nejd (Qara Nejd), Shazr (Qamar Nejd) and Sha'b are the four B. sacra ecological zones. A suffix (i) after the name (i.e. Hojari or Samhan Nejdi) is indicative of the luban produced in or associated with the respective zone. Traditional Omani B. sacra ownership, management, organization, and frankincense extraction are based on a land parcel system known as menzela. The 1970's oil boom attracted rural labor to urban and oil operation centers in Dhofar and other provinces, thus creating a labor shortage that had a profound transformative impact on frankincense production. This transformation caused frankincense extraction to evolve from an Omani-controlled system to a Somali-dominated hybrid system. Migrant Somali harvesters predominantly control the production and processing of frankincense in the field. Similarly, wholesalers occupy the next rung up the production ladder are the most powerful players in the frankincense industry. Dhofar has a long history of non-timber forest product (NTFP) extraction. From April to mid-June 1999, luban production in the Hojari/Nejdi zone of the study area was estimated at 8,710 kg with a seasonal projection of 24,840kg-30,360kg. B. sacra, a single or multiple stem shrub restricted to wadis in arid environments in or around the Dhofar Mountains, can be found at elevations from 60m above sea level in Wadi Adonib on the coastal plains to 1,770m above sea level in Wadi Kharish (a branch of Wadi Qobyr) in jabal Samhan). Land-use and landcover changes in Dhofar are threatening the fragile stability of B. sacra habitats. Frankincense trees on easily accessible flat or gently sloping terrain are susceptible to stress and mortality from

  18. Rivers through time: historical changes in the riparian vegetation of the semi-arid, winter rainfall region of South Africa in response to climate and land use.

    Science.gov (United States)

    Hoffman, M Timm; Rohde, Richard Frederick

    2011-01-01

    This paper examines how the riparian vegetation of perennial and ephemeral rivers systems in the semi-arid, winter rainfall region of South Africa has changed over time. Using an environmental history approach we assess the extent of change in plant cover at 32 sites using repeat photographs that cover a time span of 36-113 years. The results indicate that in the majority of sites there has been a significant increase in cover of riparian vegetation in both the channel beds and adjacent floodplain environments. The most important species to have increased in cover across the region is Acacia karroo. We interpret the findings in the context of historical changes in climate and land use practices. Damage to riparian vegetation caused by mega-herbivores probably ceased sometime during the early 19th century as did scouring events related to large floods that occurred at regular intervals from the 15th to early 20th centuries. Extensive cutting of riparian vegetation for charcoal and firewood has also declined over the last 150 years. Changes in the grazing history as well as increased abstraction and dam building along perennial rivers in the region also account for some of the changes observed in riparian vegetation during the second half of the 20th century. Predictions of climate change related to global warming anticipate increased drought events with the subsequent loss of species and habitats in the study area. The evidence presented here suggests that an awareness of the region's historical ecology should be considered more carefully in the modelling and formulation of future climate change predictions as well as in the understanding of climate change impacts over time frames of decades and centuries.

  19. Characterization of water and energy exchanges for rainfed olive orchards in a semi-arid land : modeling and integration of remote sensing data

    Science.gov (United States)

    Chebbi, Wafa; Le Dantec, Valérie; Boulet, Gilles; Lili Chabaane, Zohra; Fanise, Pascal; Mougenot, Bernard; Ayari, Hassan; Cheheb, Hechmi; Rivalland, Vincent; Zribi, Mehrez

    2016-04-01

    Evapotranspiration is one of the most important fluxes of the water balance in semi-arid areas. The components of evapotranspiration are soil evaporation (E) and transpiration (T) through the stomata of the plants. The estimation of crop actual transpiration is a major issue in central and south Tunisia because it affects irrigation scheduling, crop growth and yield. Olive is well adapted to the soil and climate conditions of Tunisia and covers an entire agricultural land of 1.7 million hectares representing nearly 79% of the total tree area. The southern part of the Mediterranean basin faces climate change and could affect olive tree production in rainfed conditions. The hydrological functioning of sparse olive trees is difficult to characterize because of its low LAI. For a good comprehension of the functionning of the water and energy transfers throuigh the Soil-Plant-Atmosphere continuum, we combine the eddy covariance method, soil water content measurements and sap flow method. The main objectives of this study are 1) to characterize the eco-hydrological processes of sparse olive trees from a dedicated experimental protocol and a SVAT model adapted to the sparse characteristic of such crop 2) to analyze the vulnerability of the system to climate change. First, we identify the factors of changes of transpiration at different time steps and characterized the different water stress levels by the combined use of different types of ecophysiological (sap flow) and spectral (photochemical reflectance index) measurements. Then, we estimate the percentage of evaporation, transpiration and the total evapotranspiration (ET). We compared scaled evapotranspiration values (the fraction of cover fraction contributing to the footprint of total ET fluxes) with scaled sap flow values. The sum of soil evaporation and transpiration matches well the total ET. A SVAT model is currently be applied and expanded to represent the impact of canopy structure on radiative and turbulent

  20. A regional field-based assessment of organic C sequestration and GHG balances in irrigated agriculture in Mediterranean semi-arid land

    Science.gov (United States)

    Virto, Inigo; Antón, Rodrigo; Arias, Nerea; Orcaray, Luis; Enrique, Alberto; Bescansa, Paloma

    2016-04-01

    In a context of global change and increasing food demand, agriculture faces the challenge of ensuring food security making a sustainable use of resources, especially arable land and water. This implies in many areas a transition towards agricultural systems with increased and stable productivity and a more efficient use of inputs. The introduction of irrigation is, within this framework, a widespread strategy. However, the C cycle and the net GHG emissions can be significantly affected by irrigation. The net effect of this change needs to be quantified at a regional scale. In the region of Navarra (NE Spain) more than 22,300 ha of rainfed agricultural land have been converted to irrigation in the last years, adding to the previous existing irrigated area of 70,000 ha. In this framework the project Life+ Regadiox (LIFE12 ENV/ES/000426, http://life-regadiox.es/) has the objective of evaluating the net GHG balances and atmospheric CO2 fixation rates of different management strategies in irrigated agriculture in the region. The project involved the identification of areas representative of the different pedocllimatic conditions in the region. This required soil and climate characterizations, and the design of a network of agricultural fields representative of the most common dryland and irrigation managements in these areas. This was done from available public datasets on climate and soil, and from soil pits especially sampled for this study. Two areas were then delimited, mostly based on their degree of aridity. Within each of those areas, fields were selected to allow for comparisons at three levels: (i) dryland vs irrigation, (ii) soil and crop management systems for non-permanent crops, and (iii) soil management strategies for permanent crops (namely olive orchards and vineyards). In a second step, the objective of this work was to quantify net SOC variations and GHG balances corresponding to the different managements identified in the previous step. These

  1. 宁夏中部干旱带土地利用变化及驱动力分析%Analysis on Land Use Change and Its Driving Forces in Arid Area of Central Ningxia Hui Autonomous Region

    Institute of Scientific and Technical Information of China (English)

    贾科利; 张俊华

    2011-01-01

    By using data derived from the 1978 MSS image and 1987,1996,2007 Landsat TM/ETM images and with the help of GIS,the land use change in arid area of central Ningxia Hui Autonomous Region was analyzed.At the same time,the driving forces of the land use change was identified by making use of the correlation analysis and principal component.The results showed that the overall trend of land use change in arid area of central Ningxia Hui Autonomous Region was in an enlargement of the areas of cultivated land,urban land,whereas sandy land area decreased 281 682 hm2,an average annual increase rate grassland area was 0.17%,and area of forest land reduced nearly 30 000 hm2 over 30 years.The land use information entropy indicating that the degree of disorder for land use system increased,and the structure of land use became complexity and diversity.It was considered that population,economic,regional socio-economic development degree,industrial structure,agricultural production,socio-input,government policy,and natural factors are the main driving forces inducing land use change in arid area of central Ningxia Hui Autonomous Region.More importantly,the principal component analysis showed that the impacts of human activity combining with some other conditions were the leading factors that induced dynamic change of the 1and use.%利用1978年MSS、1987年、1996年及2007年TM遥感影像,借助遥感和GIS技术及相关分析、主成分分析方法,对宁夏中部干旱带1978-2007年土地利用变化及驱动力进行了分析。结果表明:1978-2007年耕地、城镇用地面积快速增加,沙地面积减少了281 682hm2。草地以年均0.17%的速率不断增加,林地面积减少了近3万hm2。土地利用系统无序化程度增加,土地利用利用结构复杂性和多样性增大。人口、经济、产业结构、农业生产、投入、富裕程度、政策和自然因素是驱动研究区土地利用变化的主要因素,其中,人口作为社会经济活

  2. Land Degradation Control in Arid Ecosystem Under Climate Change Context%气候变化背景下干旱生态系统土地退化防治

    Institute of Scientific and Technical Information of China (English)

    江泽慧

    2012-01-01

    气候变化是当今全球陆地生态系统所面临的最大胁迫因素。探讨气候变化背景下干旱生态系统土地退化防治,增强减缓和适应气候变化的能力,逐步恢复土地生态系统原先所具有的综合生产潜力,是亟待解决的重要课题。文中分析了气候变化对干旱生态系统土地退化的影响,从综合生态系统管理的视角,探讨了保护与恢复森林、草地、农田生态系统以增强应对气候变化的能力以及改善民生的途径,以期为全球气候变化背景下土地退化防治和干旱生态系统可持续管理提供新的思路。%Climate change is the largest stress factor challenging global territorial ecosystem.The discussion on land degradation control in arid ecosystem under the context of climate change for increasing the capacity to mitigate and adapt to the climate change and gradually restoring the integrated production potential originally possessed by land ecosystem is a pressing issue to address.The paper analyzed the effect of climate change on land degradation in arid ecosystem,and described the protection and rehabilitation of forest,grassland and farmland ecosystems,the enhancement of the response to climate change and the improvement of people's livelihood from the viewpoint of integrated ecosystem management.This study is expected to offer a new concept for land degradation control and sustainable management of arid ecosystem in the context of global climate change.

  3. Environmental impacts of in-house windrow composting of broiler litter prior to land application in subtropical/semi-arid conditions

    Science.gov (United States)

    Land application to crop and pasture land is a common and effective method of utilizing the resource value of poultry litter. In-house windrow composting of litter is an emerging management practice with the potential to mitigate water quality and nuisance odor concerns associated with land applica...

  4. Simulation of Sediment Yield in a Semi-Arid River Basin under Changing Land Use: An Integrated Approach of Hydrologic Modelling and Principal Component Analysis

    Directory of Open Access Journals (Sweden)

    Charles Gyamfi

    2016-11-01

    Full Text Available Intensified human activities over the past decades have culminated in the prevalence of dire environmental consequences of sediment yield resulting mainly from land use changes. Understanding the role that land use changes play in the dynamics of sediment yield would greatly enhance decision-making processes related to land use and water resources management. In this study, we investigated the impacts of land use and cover changes on sediment yield dynamics through an integrated approach of hydrologic modelling and principal component analysis (PCA. A three-phase land use scenario (2000, 2007 and 2013 employing the “fix-changing” method was used to simulate the sediment yield of the Olifants Basin. Contributions in the changes in individual land uses to sediment yield were assessed using the component and pattern matrixes of PCA. Our results indicate that sediment yield dynamics in the study area is significantly attributed to the changes in agriculture, urban and forested lands. Changes in agriculture and urban lands were directly proportional to sediment yield dynamics of the Olifants Basin. On the contrary, forested areas had a negative relationship with sediment yield indicating less sediment yield from these areas. The output of this research work provides a simplistic approach of evaluating the impacts of land use changes on sediment yield. The tools and methods used are relevant for policy directions on land and water resources planning and management.

  5. STATUS AND DEVELOPMENT OF FLOOD LAND IN THE WEST SEMI-ARID AREA IN HEILONGJIANG PROVINCE%黑龙江省西部半干旱区河滩地治理开发构想

    Institute of Scientific and Technical Information of China (English)

    王丽敏; 高凤山; 张福平; 华淑丽

    2001-01-01

    cording to the natural conditions and the management situation of the flood land of the west semi-arid Area of Heilongjiang province, it was presented a framing conception for controlling and developing the flood land, that was to comprehensively control, for example, taking the vegetation construction as basis and by means of engineering measures, to develop all-round of agriculture, forestry, animal husbantry, water conservancy, fishery, sideline and enterprise, and to combine control with development so that flood land can become a benign system that both the local economy and the ecology will be developed.%从黑龙江省西部半干旱地区自然概况及河滩地经营现状出发,提出了以植被建设为基础,工程措施为手段,进行全面治理;根据滩地的实际情况,结合农、林、牧、水、渔、副、企各业进行综合开发,治理与开发并举,使滩地成为生态经济良性系统,促进地方经济发展与生态恢复。

  6. Community based conservation and ecotourism as an environmental management practice for climate change adaptation in Ewaso Nyiro arid land ecosystem, Samburu County Kenya

    Directory of Open Access Journals (Sweden)

    Ogara OW

    2013-05-01

    Full Text Available Communities inhabiting the fragile Arid and Semi-Arid (ASALs ecosystems of Northern Kenya are strongly impacted by climate variability and change. Their pastoral livelihoods are threatened. Community based approach to environmental resources conservation and ecotourism have provided an alternative source of livelihood worth considering. This study was conducted in two districts; Samburu and Laikipia, Northern Kenya in three community based conservancies of Namunyak, Naibung’a and Westgate. The study used quantitative and qualitative participatory research design. The findings indicated that community based conservation and ecotourism indeed was an appropriate practice for community adaptation to climate change impacts in the ASALs. It offered opportunities for livelihood diversification away from pastoralism that was resilient enough to climate change, and provided the community with a sense of ownership for their resources and created community cohesion which is an important asset for rural community social capital. The study concluded that community based conservation should be looked at as a strategy for climate change adaptation and community resource management.

  7. Assessing the Impacts of Land Use Change from Cotton to Perennial Bioenergy Grasses on Hydrological Fluxes and Water Quality in a Semi-Arid Agricultural Watershed Using the APEX Model

    Science.gov (United States)

    Chen, Y.; Ale, S.; Rajan, N.

    2015-12-01

    The semi-arid Texas High Plains (THP) region, where cotton (Gossypium hirsutum L.) is grown in vast acreage, has the potential to grow perennial bioenergy grasses. A change in land use from cotton cropping systems to perennial grasses such as Alamo switchgrass (Panicum virgatum L.) and Miscanthus giganteus (Miscanthus sinensis Anderss. [Poaceae]) can significantly affect regional hydrologic cycle and water quality. Assessing the impacts of this potential land use change on hydrology and water quality enables the environmental assessment of feasibility to grow perennial grasses in this region to meet the U.S. national bioenergy target of 2022. The Agricultural Policy/Environmental eXtender (APEX) model was used in this study to assess the impacts of replacing cotton with switchgrass and Miscanthus on water and nitrogen balances in the upstream subwatershed of the Double Mountain Fork Brazos watershed in the THP, which contains 52% cotton land use. The APEX model was initially calibrated against observed streamflow and crop yield data. Since observed data on nitrogen loads in streamflow was not available for this subwatershed, we calibrated the APEX model against the SWAT-simulated nitrogen loads at the outlet of this subwatershed, which were obtained in a parallel study. The calibrated APEX model was used to simulate the impacts of land use change from cotton to Miscanthus and switchgrass on surface and subsurface water and nitrogen balances. Preliminary results revealed that the average (1994-2009) annual surface runoff decreased by 84% and 66% under the irrigated and dryland switchgrass scenarios compared to the baseline scenarios. Average annual percolation increased by 106% and 57% under the irrigated and dryland switchgrass scenarios relative to the baseline scenarios. Preliminary results also indicated Miscanthus and switchgrass appeared to be superior to cotton in terms of better water conservation and water quality, and minimum crop management requirements.

  8. Conservation and restoration of degraded ecosystems in arid and semi-arid areas of northwest China

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In "West Development" of China, one of the most important activities is the Natural Forest Protection Program, designed to swiftly convert the focus of management and utilization of the natural forests from a timber orientation towards forest conservation, sustainable management and environmental protection. The project covered almost all the arid and semi-arid regions in Northwest region. Accompanying this great campaign this paper studied the conservation and restoration model of degraded ecosystems in arid and semi-arid lands in Northwest China. The past practices have resulted in considerably natural forest degradation and loss through land conversion (primarily for agriculture), over-harvesting, inadequate reforestation and lack of protection. The consequences have been the loss of soil and water resources, diminished timber production capacity on a sustainable basis, and environmental losses. This paper applied Aronson's restoration model and proposed the conservation, restoration, re-allocation and preservation program for the implementation of environmental improvement and natural forest conservation.

  9. Assessing the effects of land use changes on soil sensitivity to erosion in a highland ecosystem of semi-arid Turkey.

    Science.gov (United States)

    Bayramin, Ilhami; Basaran, Mustafa; Erpul, Günay; Canga, Mustafa R

    2008-05-01

    There has been increasing concern in highlands of semiarid Turkey that conversion of these systems results in excessive soil erosion, ecosystem degradation, and loss of sustainable resources. An increasing rate of land use/cover changes especially in semiarid mountainous areas has resulted in important effects on physical and ecological processes, causing many regions to undergo accelerated environmental degradation in terms of soil erosion, mass movement and reservoir sedimentation. This paper, therefore, explores the impact of land use changes on land degradation in a linkage to the soil erodibility, RUSLE-K, in Cankiri-Indagi Mountain Pass, Turkey. The characterization of soil erodibility in this ecosystem is important from the standpoint of conserving fragile ecosystems and planning management practices. Five adjacent land uses (cropland, grassland, woodland, plantation, and recreational land) were selected for this research. Analysis of variance showed that soil properties and RUSLE-K statistically changed with land use changes and soils of the recreational land and cropland were more sensitive to water erosion than those of the woodland, grassland, and plantation. This was mainly due to the significant decreases in soil organic matter (SOM) and hydraulic conductivity (HC) in those lands. Additionally, soil samples randomly collected from the depths of 0-10 cm (D1) and 10-20 cm (D2) with irregular intervals in an area of 1,200 by 4,200 m sufficiently characterized not only the spatial distribution of soil organic matter (SOM), hydraulic conductivity (HC), clay (C), silt (Si), sand (S) and silt plus very fine sand (Si + VFS) but also the spatial distribution of RUSLE-K as an algebraically estimate of these parameters together with field assessment of soil structure to assess the dynamic relationships between soil properties and land use types. In this study, in order to perform the spatial analyses, the mean sampling intervals were 43, 50, 64, 78, 85 m for

  10. The International Workshop on Environmental Changes and Sustainable Development in Arid and Semi-arid Regions

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Yang; Arthur Conacher

    2007-01-01

    @@ Arid regions,dominated by deserts,are characterized by a severe shortage of moisture,and a lack of perennial and integrated systems of drainage.Distributed over a very large range of temperatures,from the very hot to the very cold zones,arid regions cover about one third of the world's land surface and occur in every continent,including Antarctica.

  11. The current bioenergy production potential of semi-arid and arid regions in sub-Saharan Africa

    NARCIS (Netherlands)

    Wicke, B.; Smeets, E.M.W.; Watson, H.; Faaij, A.P.C.

    2011-01-01

    This article assesses the current technical and economic potential of three bioenergy production systems (cassava ethanol, jatropha oil and fuelwood) in semi-arid and arid regions of eight sub-Saharan African countries. The results indicate that the availability of land for energy production ranges

  12. The Change of Land Use/Cover and Characteristics of Landscape Pattern in Arid Areas Oasis: An Application in Jinghe, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fei; TASHPOLAT·Tiyip; Hsiang-te KUNG; DING Jianli

    2010-01-01

    This paper uses 3S technology in macroscopic. Combining the integrated technology of ecological quantity analytical method with GIS technology through ArcGIS and Fragstats, the authors study the images of 1972, 1990, 2001, and 2005 and obtained land use data in Jinghe County. Then, the change of land use/cover and landscape pattern had been analyzed in the Jinghe County of Xinjiang. The conclusions were as follows: (1) The trend of LUCC is that the area of oasis expands slowly in nearly 33years between 1972 to 2005 in Jinghe County. (2) The water area is mainly influenced by Ebinur Lake, so the area expands a little in this period. (3) The area of salinization-land expands at first and reduces later. The area of sand land decreases and the other land class increases, while the probability of transfer is always high. (4) Landscape change is also obvious throughout the decades.Overall, landscape density increases, the largest path index decreases at first and expends later, the weight area index decreases, and the shape of landscape becomes regulated. The nearest distances, the degrees of reunite, and outspread decreases. It shows that the connection of the main path in 1972 is better than 2005, wherein the patch becomes more complex. From the changes of Shannon's Diversity Index and Shannon's Evenness Index, we know that the diversity of landscape and the Interspersion Juxtaposition Index increase. The degree of diversity landscape and fragmentation increase also shows that the land uses become more complex. All in all, it is essential to intensify the spatial relationships among landscape elements and to maintain the continuity of landscape ecological process and pattern in the course of area expansion.

  13. 典型干旱区荒漠戈壁陆面参数的观测研究%Observation and Study of Land Surface Parameters over Gobi in Typical Arid Region

    Institute of Scientific and Technical Information of China (English)

    张强; 曹晓彦; 卫国安; 黄荣辉

    2002-01-01

    According to the need of popular land surface process models, characteristics and rules of some key land surface process and soil parameters over Gobi in typical arid region of Northwest China are analyzed by using the data observed during the intensive observation period of the Dunhuang Land-Surface Process Field Experiment (DLSPFE) (May-June 2000). Using the relative reflection as weighting factor, the weighted mean of the surface albedo over Dunhuang Gobi in typical arid region is calculated and its values are 0.255 -+ 0.021. After canceling the interference of the buildings, the mean values of the roughness length averaged with logarithm is 0.0019-+ 0.00071 m. After removing the influence of the oasis, the soil wetness factor computed with data under condition of no precipitation is 0.0045. After removing the influence of the precipitation, the mean values of the soil heat capacity over Dunhuang Gobi in typical arid region is 1.12 ×l06 J m -3K-1, a bit smaller than the values observed in HEIFE. But the soil heat diffusivity and conductivity are about one of those observed in HEIFE. The soil water content over Dunhuang Gobi in typical synoptic condition is very little and does not exceed 1% basically.%根据目前流行的陆面过程模式的需要,利用2000年5-6月敦煌陆面过程野外观测实验加强期的观测资料,分析了西北典型干旱区荒漠戈壁的一些关键陆面过程和土壤参数的特征和规律.并且利用相对反射为权重加权平均,计算得到典型干旱区敦煌荒漠戈壁的平均反射率为0.255±0.021;剔除建筑物干扰后,利用对数平均法计算的粗糙度长度平均值为0.0019±0.0007l m;剔除绿洲影响后,用无降水影响的资料确定出土壤湿度影响因子为0.0045;剔除降水影响后,用观测资料计算的敦煌典型干旱区荒漠戈壁的热容量平均值为l 1 2×l06J m-3 K-1,比"黑河试验"在戈壁和在其它沙漠观测的有关值略小一些,但热扩散率和热传

  14. The potential for SLM, facing human constraints, the case of the semi-arid agro-pastoral lands in the Atlantic plateaus, Morocco

    Science.gov (United States)

    Laouina, A.; Chaker, M.; Aderghal, M.; Machouri, N.; Alkarkouri, J.

    2012-04-01

    The agro-pastoral activity through its evolution, in the Atlantic plateaus of Morocco, led to unsuitable forms of resources use, which carried damage in the balance of water and the stability of land. It was thus necessary to start a revision of these practices and to set up improved forms of land use. The research made in the framework of the DESIRE project concerns the Sehoul commune, which presents a high rate of poverty and illiteracy, in spite of its location near Rabat, the capital of the country. Farming has as main objective to feed the livestock. The rain-based cereal cultivations, which still occupy more than 80% of the agricultural surface, reveals the stagnation of the techniques adopted and of the local knowledge. In collaboration with various stakeholders, technicians and farmers, the assessment with the WOCAT approach permitted to identify the main factors of constraints, responsible of the current spreading of land degradation mechanisms (forest clearing, shrubs cutting on the pastoral slopes, soil erosion, constitution of rills in the recently ploughed fields, incision of gullies and channels, mass movements on the banks of the deepest channels). These constraints derive from social evolution of the population during the last 60 years and mainly the rapid transformation of the rural structure of families to a new kind of farmers, more interested by what they can earn during their frequent movements to the city than by their own traditional agriculture. Due to the penetration of urban investment, direct overgrazing and indirect effect related to mismanagement of land for fodder production, operate massive damages to the vegetation cover and to the soil. It is why the SLM behavior, approaches and techniques have a very low rate of chance for success, without a deep change in term of land ownership, law constraints, agrarian structures, relations between the city and its vicinity, etc. Scenarios were built, based on various rates of land management

  15. Sustainability of Smallholder Agriculture in Semi-Arid Areas under Land Set-aside Programs: A Case Study from China’s Loess Plateau

    Directory of Open Access Journals (Sweden)

    Qirui Li

    2016-04-01

    Full Text Available This article analyzes agricultural sustainability in the context of land degradation, rural poverty and social inequality, taking China’s Loess Hills as an example. The analysis attempts to understand the multi-dimensionality of sustainability at the farm level and its relationship with physical-socio-economic-infrastructural-technological framework conditions in the context of the land set-aside program viz. the Grain for Green Project (GGP. We developed composite indices of sustainability and its environmental, economic and social dimensions using a principal component analysis (PCA-based weighting scheme. Regression analyses were conducted to examine the relationship between the estimated sustainability indicators and the variables representing framework conditions of knowledge, demographics, resource endowment and production techniques. The stated analysis was conducted on a dataset collected by means of household surveys in 2014 in valleys and flood plain areas in Yanhe Township. Findings reveal hidden correlations among the indicators of environmental, economic, and social pillars of sustainability. The ratio of land under the conservation program to actual farmland emerged as a key determinant of overall agricultural sustainability and its social dimension, which reaches the maximum when the ratio is around 0.56 and 0.64, respectively. The results also show that there is need to balance off-farm and on-farm income diversification as well as highlight the role of women in ensuring the sustainability of farming households. The core achievement of the article is the definition of the thresholds for the land set-aside program and the identification of major determinants of agricultural sustainability in the rural Chinese context in particular and in rural farming communities in general.

  16. Using a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to Simulate the Interaction between Land Surface Processes and Atmospheric Boundary Layer in Semi-Arid Regions

    Institute of Scientific and Technical Information of China (English)

    刘树华; 乐旭; 胡非; 刘辉志

    2004-01-01

    This paper uses a Modified Soil-Plant-Atmosphere Scheme (MSPAS) to study the interaction between land surface and atmospheric boundary layer processes. The scheme is composed of two main parts:atmospheric boundary layer processes and land surface processes. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feasibility of the model is well proved in this paper. The numerical simulation results from MSPAS show good agreement with reality. The scheme is used to obtain reasonable simulations for diurnal variations of heat balance, potential temperature of boundary layer, and wind field, and spatial distributions of temperature, specific humidity, vertical velocity,turbulence kinetic energy, and turbulence exchange coefficient over desert and oasis. In addition, MSPAS is used to simulate the interaction between desert and oasis at night, and again it obtains reasonable results.This indicates that MSPAS can be used to study the interaction between land surface processes and the atmospheric boundary layer over various underlying surfaces and can be extended for regional climate and numerical weather prediction study.

  17. The causes of land landscape changes in semi-arid area of Northwest China:a case study of Yulin city%中国西北半干旱区土地景观变化成因--以榆林市为例

    Institute of Scientific and Technical Information of China (English)

    郭丽英; 任志远; 刘彦随

    2006-01-01

    Rapid land landscape change has taken place in many arid and semi-arid regions such as the vulnerable ecological area over the last decade. In this paper, we quantified land landscape change of Yulin in this area between 1985 and 2000 using remote sensing and GIS. It was found that fallow landscape decreased by 125,148 hm2 while grassland and woodland increased by 107,975 hm2 and 17,157hm2, respectively. The major factors responsible for these changes are identified as the change in the government policy on preserving the environment, continued growth in mining, and urbanization. The efforts in restoring the deteriorated ecosystem have reaped certain benefits in reducing the spatial extent of sandy land through replacement by non-irrigated farmland, woodland and grassland. On the other hand,continued expansion of mining industry and urbanization has exerted adverse impacts on the land landscape. At present regional economic development conflicts directly with the protection of the natural environment. Such a conflict has caused the destruction to the land resources and fragmentation of the landscape accompanied by land desertification, the case is even serious in some localities.

  18. The evaluation on interaction between structures and succession of vegetation/ecosystems and arid land environment in western China: a case study on Fukang, Xinjiang

    Science.gov (United States)

    Pan, Xiaoling; Gao, Wei; Gu, Fengxue; Li, Weiqing; Chang, Shunli; Zhang, Yuandong; Ye, Qian; Anabiek, Subai

    2003-07-01

    This article discusses the relationship between desert ecosystem structures, succession and environment factors which include soil moisture, salt content and pH values in Fukang of Xinjiang. Some preliminary conclusions have been drawn as following: (1) In the study area the niche breadth of typical species in desert vegetation/ecosystem is closely related to environment factors, such as soil moisture, soil pH and salinity. The biggest niche breadth species are Haloxylon ammodendron (1.412) and Reaumuria soongorrica (1.399), which are dominant species in climax communities of the region, and they have very strong adaptability to the arid desert environment. The niche breadths of Nitraria rovorowskii, Kalidium foliatum and Suaeda acuminata range from 0.8 to 1.2. The smallest niche breadth species are Tamarix spp. and Anabasis spp., ranging from 0.4 to 0.8, and both of them show sensitivity to drought and salinity. (2) Low species diversity in desert vegetation/ecosystem of Fukang was found. In general, the grade of community diversity from high to low is defined as: Tamarix soongorica community, Kalidium foliatum community, Suaeda physophora community, Halocnemum strobilaceum community, Haloxylon ammodendron community, Salsola passerina community, Reaumuria soongorica community, Bassia spp. community and Suaeda acuminate community. The most important factors that influence the species diversity of communities are soil salinity and pH values. Because of saline-sodic environment desert vegetation has developed a saline-sodic endurance ecological type. The main effects of salinity on vegetation are observed in the change of dominant and constructive species in communities, and halophyte becomes the dominant species gradually. (3) The limit factor on secondary succession in regional ecosystem is soil salinization. The trend and phase of community succession are in accordance with soil salinization development. There are three soil types: non-salinity, saline soil, and

  19. A methodology for small scale rural land use mapping in semi-arid developing countries using orbital imagery. Part 6: A low-cost method for land use mapping using simple visual techniques of interpretation. [Spain

    Science.gov (United States)

    Vangenderen, J. L. (Principal Investigator); Lock, B. F.

    1976-01-01

    The author has identified the following significant results. It was found that color composite transparencies and monocular magnification provided the best base for land use interpretation. New methods for determining optimum sample sizes and analyzing interpretation accuracy levels were developed. All stages of the methodology were assessed, in the operational sense, during the production of a 1:250,000 rural land use map of Murcia Province, Southeast Spain.

  20. Mean Characteristics of Land Surface Key Parameters in Semi-Arid and Arid Regions of China in Summer of 2008%2008年夏季中国干旱-半干旱区陆面主要物理参数的平均特征

    Institute of Scientific and Technical Information of China (English)

    曾剑; 张强

    2012-01-01

    By picking 12stations whose underlying land surfaces include grassland,cropland,orchard and forest,the climatic characteristics of land surface key parameters are investigated using the data measured from July to September 2008,provided the Northern China Observation Coordination and Integration Research in Semiarid and Arid Regions.The roughness lengths for momentum,sensible heat and water vapor,and bulk transfer coefficient,albedo,and soil thermal conductivity and diffusivity are calculated and compared within various underlying land surfaces.The results are compared with the model theoretic reference values as well.It shows that the thermal-hydrologic properties of vegetated land surface and vegetation height significantly influence some key land surface parameters,and that there is no evident relations between soil thermal conductivity and diffusivity and underlying surface types.Specifically aerodynamic roughness length and momentum drag coefficient increase with increasing vegetation height,but albedo decreases with vegetation height.The measured aerodynamic roughness length of grassland is smaller than model reference value,but it is not true for cropland and orchard.The measured momentum drag coefficient is larger than model reference value over grassland,but it is smaller than model reference value in other underlying surfaces.The measured albedo is basically lower than its model reference value although it lies between visible albedo and near-infrared albedo.%采用2008年7-9月观测的中国干旱-半干旱区试验观测协同与集成研究资料,选取12个测站(涵盖不同气候环境区的草地、农田、果林和森林等下垫面)比较分析了干旱-半干旱区的动力、热力和水汽粗糙度长度、总体输送系数、反照率以及土壤热传导率和热扩散率的夏季平均特征,并与陆面模式的理论参考值进行了对比。结果表明,植被下垫面的水、热特性和植被高度对主要陆面参数有重

  1. Assessment of Impacts of Changes in Land Use Patterns on Land Degradation/Desertification in the Semi- arid Zone of White Nile State, Sudan, by Means of Remote Sensing and GIS

    OpenAIRE

    2014-01-01

    In Sudan, land degradation/desertification (LDD) has devastated large areas and consequently, it includes social, economic, and environmental aspects. LDD results from various factors, including climatic variation and human activities. Probably the LU practices and their changes have contributed to an increase of LDD in that area. Remote sensing technology has become unique and developed tool for providing temporal and spatial information for the LDD research and other environmental aspects. ...

  2. A methodology for small scale rural land use mapping in semi-arid developing countries using orbital imagery. Part 4: Review of land use surveys using orbital imagery outside of the USA

    Science.gov (United States)

    Vangenderen, J. L. (Principal Investigator); Lock, B. F.

    1976-01-01

    The author has identified the following significant results. Outside the U.S., various attempts were made to investigate the feasibility of utilizing orbital MSS imagery in the production of small scale land use maps. Overall, these studies are not as elaborate or extensive in their scope as the U.S. ones, and generally the non-U.S. investigators have employed nonsophisticated and less expensive techniques. A representative range of studies is presented to demonstrate the approaches and trends dealing with reprocessing, interpretation, classification, sampling, and ground truth procedures.

  3. The challenges of rehabilitating denuded patches of a semi-arid environment in Kenya

    NARCIS (Netherlands)

    Mganga, K.Z.; Nyangito, M.M.; Musimba, N.K.R.; Nyariki, D.M.; Mwangombe, A.W.; Ekaya, W.N.; Muiri, W.M.; Clavel, D.; Francis, J.; Kaufmann, Von R.; Verhagen, J.

    2010-01-01

    Land degradation is a major problem in the semi-arid environments of Sub-Saharan Africa. Fighting land degradation is essential to ensure the sustainable and long-term productivity of the habited semiarid lands. In Kenya, grass reseeding technology has been used to combat land degradation. However,

  4. Oils and rubber from arid land plants

    Science.gov (United States)

    Johnson, J. D.; Hinman, C. W.

    1980-05-01

    In this article the economic development potentials of Cucurbita species (buffalo gourd and others), Simmondsia chinensis (jojoba), Euphorbia lathyris (gopher plant), and Parthenium argentatum (guayule) are discussed. All of these plants may become important sources of oils or rubber.

  5. Experimental research on retrieving machine for film residue with whole plastic film mulching on double ridges in arid land%旱地全膜双垄沟残膜回收机的试验研究

    Institute of Scientific and Technical Information of China (English)

    王松林; 敬志臣; 韩正晟; 王波; 戴飞; 高爱民

    2015-01-01

    针对西北旱地全膜双垄沟残膜回收机回收率低的问题,采用正交试验法对残膜回收机的起膜齿齿数、搂膜耙齿齿径、起膜齿入土深度进行研究,并对试验结果进行方差分析,优化了关键部件参数,确定了残膜回收机最佳工作性能参数.即起膜齿齿数为4个,前、中、后搂膜耙齿齿径组合为10-8-6 mm,起膜齿入土深度为50 mm.重复试验结果表明:回收机残膜回收率为93.4%>75%,很好地满足了残膜回收的农艺要求.%Aimed at the problem of lower rate recycling of plastic film collector for whole mulching on double ridges in northwestern arid land,orthogonal test method was used for the study on number of cut-ting film teeth,diameter of collecting film teeth and buried depth of the cutting film teeth.The experimen-tal results were analyzed by variance analysis,and the key component parameters were optimized.The best working performance parameters of the collector were discovered as follows:the number of cutting film teeth was 4,the combination diameter of front,middle and back collecting film teeth was 10-8-6 mm,and the buried depth of the cutting film teeth was 50 mm.The results of replicated tests showed the rate of re-cycling of film was 9 3 .4%>7 5%,which well met the agronomic requirements.

  6. Impact of grazing on range plant community components under arid Mediterranean climate in northern Syria

    NARCIS (Netherlands)

    Niane, A.A.

    2013-01-01

    Keywords: Rotational grazing, full protection, continuous grazing species richness, species diversity, soil seed bank, Bayesian methods, Salsola vermiculata, seed longevity, rangeland management, Syria.   Rangelands represent 70% of the semi-arid and arid Mediterranean land mass. It is a n

  7. Aridity under conditions of increased CO2

    Science.gov (United States)

    Greve, Peter; Roderick, Micheal L.; Seneviratne, Sonia I.

    2016-04-01

    A string of recent of studies led to the wide-held assumption that aridity will increase under conditions of increasing atmospheric CO2 concentrations and associated global warming. Such results generally build upon analyses of changes in the 'aridity index' (the ratio of potential evaporation to precipitation) and can be described as a direct thermodynamic effect on atmospheric water demand due to increasing temperatures. However, there is widespread evidence that contradicts the 'warmer is more arid' interpretation, leading to the 'global aridity paradox' (Roderick et al. 2015, WRR). Here we provide a comprehensive assessment of modeled changes in a broad set of dryness metrics (primarily based on a range of measures of water availability) over a large range of realistic atmospheric CO2 concentrations. We use an ensemble of simulations from of state-of-the-art climate models to analyse both equilibrium climate experiments and transient historical simulations and future projections. Our results show that dryness is, under conditions of increasing atmospheric CO2 concentrations and related global warming, generally decreasing at global scales. At regional scales we do, however, identify areas that undergo changes towards drier conditions, located primarily in subtropical climate regions and the Amazon Basin. Nonetheless, the majority of regions, especially in tropical and mid- to northern high latitudes areas, display wetting conditions in a warming world. Our results contradict previous findings and highlight the need to comprehensively assess all aspects of changes in hydroclimatological conditions at the land surface. Roderick, M. L., P. Greve, and G. D. Farquhar (2015), On the assessment of aridity with changes in atmospheric CO2, Water Resour. Res., 51, 5450-5463

  8. CHARACTERISTICS OF ARIDITY CONDITIONS IN SOUTH DOBRUDJA

    Directory of Open Access Journals (Sweden)

    A. TISCOVSCHI

    2013-04-01

    Full Text Available Characteristics of Aridity Conditions in South Dobrudja. For most people, the arid and semi-arid lands are those where precipitation is low (less than 200 mm per year, and yet enough for supplying streams capable of temporarily carrying the debris resulted from weathering, but insufficient for encouraging the development of a vegetal cover meant to protect the soil blanket against eroding agents. The drought is a major and permanent climatic risk for the Dobrudja territory as a whole and for South Dobrudja in particular, a territory where hydrographic network is underdeveloped, streams are ephemeral, and semi-endorheic areas are well developed. When the period of moisture deficiency lasts longer, it can bring about a significant water imbalance, which results in crop losses or restrictions in water consumption, thus leading to a number of economic problems. Under the circumstances, the risk of aridity expansion is significant, this being the reason why a better water management system in Romania is urgently needed. In the last decades, the numerous specialty studies undertaken in the area have emphasized an intensification of the process of dryness, because atmospheric and pedological droughts have become more and more serious. Romania is a member of the United Nations Convention to Combat Desertification (UNCCD and the World Meteorological Organization (WMO. It actively participates within the drought management network and the Drought Management Center for Southeastern Europe, which comprises 11 countries. The scope is to work together and exchange experience with the neighboring countries that have recorded positive results and acquired a rich experience in terms of drought management. The employment of appropriate pluvial indices in identifying the areas prone to aridity may prove to be convenient tool for finding practical solutions meant to mitigate the impact of this phenomenon on the local communities living in South Dobrudja.

  9. Interspecific facilitation and critical transitions in arid ecosystems

    NARCIS (Netherlands)

    Verwijmeren, Mart; Rietkerk, Max; Wassen, Martin J.; Smit, Christian

    2013-01-01

    Climate change and intensified land-use impose severe stress on arid ecosystems, resulting in relatively rapid degradation which is difficult to reverse. To prevent such critical transitions it is crucial to detect early warning signals. Increased patchiness' smaller and fewer vegetated patches is t

  10. Simulation of water use and herbage growth in arid regions

    NARCIS (Netherlands)

    Keulen, van H.

    1975-01-01

    The and and semi-arid regions of the world, totalling about 30% of the land surface of the earth, are predominantly used for extensive grazing, as low and erratic rainfall presents too high a risk for arable farming. The population that can be sustained by the animal products -meat, milk or wool- is

  11. 干旱区典型绿洲土地利用动态变化分析——以且末绿州为例%Analysis on Dynamic Change of Land Use in Typical Arid Region Oasis -- A Case Study of Qerqen Oasis

    Institute of Scientific and Technical Information of China (English)

    努尔比娅·乌斯曼; 李新国; 吐尔逊古丽·托合提; 吐尔逊·艾山乳

    2011-01-01

    文章以干旱区典型的条带状绿洲一且末绿洲为例,以1972年MSS、1990年TM、2000年和2005年ETM+遥感影像为数据源.结合野外考察数据,选择适宜的分类指标体系,对遥感图像进行了监督分类,并获得了研究区土地利用/覆盖转移矩阵。研究结果表明,近33年来耕地面积一直呈现出增加的趋势,增加了92.588km^2,耕地面积的增加量主要是由草地和林地的转化而来,是增加最快的土地利用类型;林地和草地面积一直呈逐渐减少的趋势,其中减少最多的土地类型是林地,减少了65.641km^2,林地面积的减少由林地转移草地、水体和耕地的比例超过草地转移林地的比例而引起;草地面积减少了62.01km^2,这主要是由一部分草地转移耕地、一部分转移未利用地而引起;水域面积总体上有增加趋势,增加了22.073km^2,这主要由草地和未利用地转移水体而引起;未利用地变化幅度不大,有缓慢增加的趋势,增加了13.105km^2。%Qerqan Oasis-a typical Oasis in arid area was chosen as an example, the remote sensing images of MSS in 1972, TM in 1990, ETM+ in 2000 and 2005 were used as major data sources, be combined with fieldwork data, the appropriate disaggregated indicators system was selected to classify the images, and classified the images, and then obtained the different types of land use / cover transition matrix. The results showed that the cultivated area had been showing an increasing trend in the last 33 years, it was increased 92. 588km^2 , the increase of the cultivated land is mainly from the conversion of grassland and woodland, the cultivated land is the fastest growing land use type. Woodland and grassland had been gradually decreasing trend, and most reduced land type was the forest land, it was decreased 65. 641km^2. This was mainly caused by the conversion proportion area of woodland to the grassland,water land and

  12. Organic textile waste as a resource for sustainable agriculture in arid and semi-arid areas.

    Science.gov (United States)

    Eriksson, Bo G

    2017-03-01

    New vegetation in barren areas offers possibilities for sequestering carbon in the soil. Arid and semi-arid areas (ASAs) are candidates for new vegetation. The possibility of agriculture in ASAs is reviewed, revealing the potential for cultivation by covering the surface with a layer of organic fibres. This layer collects more water from humidity in the air than does the uncovered mineral surface, and creates a humid environment that promotes microbial life. One possibility is to use large amounts of organic fibres for soil enhancement in ASAs. In the context of the European Commission Waste Framework Directive, the possibility of using textile waste from Sweden is explored. The costs for using Swedish textile waste are high, but possible gains are the sale of agricultural products and increased land prices as well as environmental mitigation. The findings suggest that field research on such agriculture in ASAs should start as soon as possible.

  13. 应用空间技术研究干旱和半干旱地区由盐化作用造成的土地退化%Land Degradation Due to Salinization in Arid and Semi-arid Regions with the Aid of Geo-information Techniques

    Institute of Scientific and Technical Information of China (English)

    Mushtak T.Jabbar; 陈晓玲

    2008-01-01

    This study applied a computerized parametric methodology to monitor, map, and quantify land degradation by salinization risk detection techniques at a 1: 250000 mapping scale using geo-information technology. The northern part of the Shaanxi province in China was taken as a case. Multi-temporal remotely sensed materials of both Landsat TM and thematic maps (ETM+) were used as the bases to provide comprehensive views of surface conditions such as vegetation cover and salinization detection. With ERDAS ver. 9.1 software, the Normalized Differential Salinity Index (NDSI) and Salinity Index (S. I.) were computed and then evaluated for land degradation by salinization. Arc/Info ver. 9.2 software was used along with field observation data (GPS) for analysis. Using spatial analysis methods, results showed that 19973.1km2 (72%) of land had no risk of land degradation by salinization, 3684.7km2 (13%) had slight land degradation by salinization risk, 2797.9km2 (10%) had moderate land degradation by salinization risk, and 1218.9km2 (4%) of the total land area was at a high risk of land degradation by salinization. The study area, in general, is exposed to a high risk of soil salinization.

  14. Determine the optimum spectral reflectance of juniper and pistachio in arid and semi-arid region

    Science.gov (United States)

    Fadaei, Hadi; Suzuki, Rikie

    2012-11-01

    Arid and semi-arid areas of northeast Iran cover about 3.4 million ha are populated by two main tree species, the broadleaf Pistacia vera. L (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but genetically essential as seed sources for pistachio production in orchards. In this study, we estimated the optimum spectral reflectance of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. In this research spectral reflectance are able to specify of multispectral from Advanced Land Observing Satellite (ALOS) that provided by JAXA. These data included PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, has one band with a wavelength of 0.52-0.77 μm and AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, has four multispectral bands: blue (0.42-0.50 μm), green (0.52-0.60 μm), red (0.61-0.69 μm), and near infrared (0.76-0.89 μm). Total ratio vegetation index (TRVI) of optimum spectral reflectance of juniper and pistachio have been evaluated. The result of TRVI for Pistachio and juniper were (R2= 0.71 and 0.55). I hope this research can provide decision of managers to helping sustainable management for arid and semi-arid regions in Iran.

  15. 采用随机森林法的天绘数据干旱区城市土地覆盖分类%Random forest classification of land cover information of urban areas in arid regions based on TH-1 data

    Institute of Scientific and Technical Information of China (English)

    田绍鸿; 张显峰

    2016-01-01

    基于天绘一号(TH-1,或称MS-1)卫星多光谱数据,采用随机森林分类方法(random forests classification,RFC)对位于中亚干旱区的我国新疆维吾尔族自治区阿勒泰地区北屯市及周边区域的土地覆盖进行了分类研究.针对北屯市不透水层与裸土混杂的情况,将纹理特征与植被信息构建最优组合,建立有效的RFC分类器,提高对易混淆土地覆盖类型的分类识别精度.结果表明,采用RFC的分类精度高于最大似然法分类结果,总体分类精度提高了近10%.经过优化选择的特征组合在对干旱区中小城市土地覆盖进行分类时表现良好,能得到较高精度的分类结果,可满足新疆中小城市发展规划对土地覆盖信息的需求.%Random-forest classification (RFC) method was used to extract the land cover information from the TH-1 satellite remotely sensed multispectral data in Beitun Town and its adjacent areas within the arid region of Altay,Xinjiang.Owing to the mixture of the impervious covers and the exposed soils inside the city,the textural and vegetation features were derived from the TH-1 panchromatic image and multispectral bands and subsequently applied to creating optimal feature set so as to implement the RFC classification.The optimized classifier can achieve better identification of some confused land cover classes.The results show that the RFC possesses higher accuracy than the conventional maximum likelihood classification (MLC)with the same TH-1 image,with their total accuracy being 82.26% and 72.61%,respectively.In addition,favorable applicability is observed in the land cover classification in the arid urban region using optimized combined multi-feature methods,which can provide land cover information for the urban development and planning in the medium and small cities of Xinjiang.

  16. Quantification of the Aridity Process in South-Western Romania

    Directory of Open Access Journals (Sweden)

    Daniel Peptenatu

    2013-05-01

    Full Text Available The report released by the Intergovernmental Committee for Climate Change indicates that Romania ranks among the top seven countries in Europe that would be strongly impacted by aridity in the next few years, with climate changes consisting in a rise of average annual temperatures by as much as 5°C. The research work was conducted in the South of the Oltenia South-Western Development Region, where more than 700,000 hectares of farmland is impacted by aridification, more than 100,000 hectares among them impacted by aridity. Research methodology encompassed the analysis of average annual temperatures over the time span data was available for, at three weather stations, an analysis of average annual precipitations, an analysis of the piezometric data, the evolution of land use as a result of the expansion of the aridity process. The assessment of the aridity process also involved taking into consideration the state of the vegetation by means of the normalized difference vegetation index (NDVI, used to assess the quality of the vegetal stratum, an important element in the complex analysis of the territory. The aridity process is an effect of global warming, and, based on the results of this study, the post-1990 escalation of its effects was brought about by socio-economic factors. The destruction of the irrigation systems and protective forest belts because of the uncertain situation of land ownership are the main factors that contributed to amplification of the effects of aridity on the efficiency of agricultural systems that nowadays are exposed to very high risks.

  17. Spatial distribution and comparison of aridity indices in Extremadura, southwestern Spain

    Science.gov (United States)

    Moral, Francisco J.; Rebollo, Francisco J.; Paniagua, Luis L.; García-Martín, Abelardo; Honorio, Fulgencio

    2016-11-01

    In semi-arid lands with warm climates, aridity is a real hazard, with the threat of desertification because of greater precipitation variability and prolonged droughts. Aridity indices can be used to identify areas prone to desertification. The present study aimed to analyse the spatial distribution of aridity in Extremadura, southwestern Spain, using three indices: the De Martonne aridity index ( I DM), the Pinna combinative index ( I P), and the Food and Agriculture Organization (FAO) aridity index ( I F). Temperature, precipitation, and evapotranspiration data from 90 weather stations located throughout Extremadura and 27 along boundaries with at least 30-year length (within the 1980-2011 period) were used to compute each index at each station. The statistical properties of each aridity index were assessed, and later, they were mapped by means of an integrated geographic information system (GIS) and a multivariate geostatistical (regression-kriging) algorithm in which exhaustive secondary information on elevation was incorporated. Annual and seasonal I DM and I F, and annual I P-kriged maps were generated. According to annual I DM, the semi-arid and Mediterranean conditions are predominant in the region, covering about 70 % of the territory, while about 94 % of the areas are classified as dry and semi-dry Mediterranean based on annual I P and about 86 % are classified as semi-arid and dry categories based on annual I F. The most vulnerable to aridity are the natural regions located to the west, the south, and the southeast of Extremadura, especially during summer, when arid conditions are found across the region. Although the three aridity indices were highly correlated, displaying similar spatial patterns, I DM was preferred because it can better discriminate different climate conditions in Extremadura.

  18. A PROPOSED NEW VEGETATION INDEX, THE TOTAL RATIO VEGETATION INDEX (TRVI, FOR ARID AND SEMI-ARID REGIONS

    Directory of Open Access Journals (Sweden)

    H. Fadaei

    2012-07-01

    Full Text Available Vegetation indices that provide important key to predict amount vegetation in forest such as percentage vegetation cover, aboveground biomass, and leaf-area index. Arid and semi-arid areas are not exempt of this rule. Arid and semi-arid areas of northeast Iran cover about 3.4 million ha and are populated by two main tree species, the broadleaf Pistacia vera (pistachio and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper. Natural stands of pistachio in Iran are not only environmentally important but also genetically essential as seed sources for pistachio production in orchards. We investigated the relationships between tree density and vegetation indices in the arid and semi-arid regions in the northeast of Iran by analysing Advanced Land Observing Satellite (ALOS data PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, and has one band with a wavelength of 0.52–0.77 μm (JAXA EORC. AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, and has four multispectral bands: blue (0.42–0.50 μm, green (0.52–0.60 μm, red (0.61–0.69 μm, and near infrared (0.76–0.89 μm (JAXA EORC. In this study, we estimated various vegetation indices using maximum filtering algorithm (5×5 and examined. This study carried out of juniper forests and natural pistachio stand using Advanced Land Observing Satellite (ALOS and field inventories. Have been compared linear regression model of vegetation indices and proposed new vegetation index for arid and semi-arid regions. Also, we estimated the densities of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. We present a new vegetation index for arid and semi-arid regions with sparse forest cover, the Total Ratio Vegetation Index (TRVI, and we investigate the relationship of the new index to tree density by

  19. Study on Land Surface Characteristics and Its Relationship with Land Surface Thermal Environment of Typical City in Arid Region%干旱区典型城市下垫面特征及其与地表热环境的关系研究

    Institute of Scientific and Technical Information of China (English)

    买买提江·买提尼亚孜; 阿里木江·卡斯木

    2015-01-01

    Landsat TM images of August 11th, 2011 were used to acquire the abundance of impervious surface Area (ISA) and vegetation fraction (FV) information of Urumqi city’s build-up area based on Linear Spectral. Unmixing Model, and land surface temperature (LST) was retrieved using Mono-Window Algorithm of that area as well, then spatial distribution characteristics of these factors were analyzed based on hierarchical method. On basis of this, the correlation relationship between abundance of ISA, FV and LST was analyzed respectively. The results show that: (1)Linear Spectral Unmixing Model is proved to be a method with low cost and high precision in extracting ISA when using medium resolution remote sensing image in this case (RMS is 0.003, much smaller than the threshold value 0.02), and it has advantages of distinguishing urban construction land and bare soil which have similar spectral characteristics; (2) Abundance of ISA is positively correlated with LST with R square of 0.69, and FV is negatively correlated with LST with R square of 0.74; (3) Bare soil has significant influence on the formation of heat island and the surface thermal environment of cities in arid region because of extremely high LST, so reducing and changing bare soil of cities in arid region is very helpful to mitigate urban heat island effect and improve the thermal environment of the whole city.%基于2011年8月11日Landsat TM遥感影像,利用混合光谱线性分解模型提取乌鲁木齐市建成区下垫面不透水面丰度和植被覆盖度信息,利用单窗算法定量反演建成区地表温度,并通过分级方法分析两个要素的空间分布特征;在此基础上,利用回归模型对乌鲁木齐市建成区不透水面丰度、植被覆盖度与地表热环境之间的关系进行相关性分析。结果表明:(1)利用混合光谱线性分解方法,基于中等分辨率TM影像提取干旱区城市乌鲁木齐建成区不透水面,成本低,精度高

  20. Characteristics and laws of MODS coupling relation in arid zone under global change

    Institute of Scientific and Technical Information of China (English)

    WANG Ranghui; ZHANG Huizhi; HUANG Qing

    2006-01-01

    Global change has influenced the distribution pattern and spatio-temporal changes of resources in arid zone, and has restrained the land use and land cover change, which is shown by water-heat state, landscape structure, climate effect, and human activities. The above-mentioned characteristics have a close coupling relation with the mountain-oasisdesert system (MODS). The climate in Central Asia arid zone is warm and wet, which is different from that in northern China which takes a tendency of aridity, and the mechanism has restricted the characteristics and laws of MODS. Systematic interface characteristics and process, especially the formation,transformation and consumption laws of water resource reflect directly MODS's response to global change in arid zone. Spatio-temporal pattern, dynamic change, scale change and coupling mode of MODS reflect the ecology mechanism between the systems and within the systems.

  1. 半干旱区气候变化背景下近20年内蒙古武川县耕地质量变化%Cultivated land quality change of Wuchuan county in Inner Mongolia under background of climate change in semi-arid regions during recent 20 years

    Institute of Scientific and Technical Information of China (English)

    王立为; 安萍莉; 潘志华; 赫迪; 董智强

    2013-01-01

    Cultivated land quality is a key factor of national economic and social sustainable development. The change of cultivated land quality with climate change has become one of the hot research areas in global change in recent years. Based on the meteorological data, soil information and field experimental data were used, utilizing the Wageninngen method recommended by the Food and Agriculture Organization (FAO) to calculate the potential productivity of potato and spring wheat from 1989 to 2009 in Wuchuan County, Inner Mongolia, a typical semi-arid climate-sensitive area in North China. We examined the influence of climate change on production potential, the standard cropping system, and the yield. Further, by the method of regulations of Farmland classification, we used the data of potential productivity and land use to analyze the changes of natural quality grades and utilization grades under climate change. The results showed that:(1) The annual temperature of Wuchuan County increased at an average rate of 0.57℃/10a during 1967-2009. The precipitation varied greatly among the years, and the annual precipitation declined slightly over time. The soil relative humidity in soil layers 0-10 cm and 10-20 cm depth in crop growing season (April-September) in the period 1989-2009 had a decreasing trend with an average rate of 1.8%/a and 1.5%/a, respectively. Drought index increased noticeably. In conclusion, Wuchuan County was getting warmer and dryer under climate change. (2) Most of the cultivated lands were the dry lands in Wuchuan county (accounting for more than 90%), but the irrigated lands increased in recent years. The main crop in Wuchuan county was potatoes in 2009 instead of spring wheat in 1989. The planting area of potatoes increased from 8.4%to 39.8%, while spring wheat planting area decreasing from 52.1%to 17.1%in the period 1989-2009. (3) The production potential of the potatoes and spring wheat showed a declining trend under the dry warming climate in

  2. Pollen transport in the Shiyang River drainage, arid China

    Institute of Scientific and Technical Information of China (English)

    ZHU Yan; XIE Yaowen; CHENG Bo; CHEN Fahu; ZHANG Jiawu

    2003-01-01

    In order to assess the contribution of the pollen transported by wind and fluvial flows to the pollen spectra in Shiyang River drainage, a typical small endorheic drainage in arid lands of northwest China, preliminary studies on modern pollen rain along two transects with 91 surface soil samples, 8 atmospheric samples, 30 modern fluvial flow samples and 50 riverbed mud samples, were carried out. Results show that dispersal agents (air, flowing water) have dissimilareffects on transport of pollen and the structure of pollen spectra. Fluvial flow has a stronger capacity than wind to transport large quantities of pollen overlong distances. Pollen transported by fluvial flow makes a large contribution to the pollen spectra of riverbed alluvial sediments. Paleoenvironmental reconstructions undertaken using pollen spectra from fluvial sediments in arid lands arestrongly influenced by pollen transport. Therefore, the sources, the transportation agents and the depositional condition of pollen should be systematically investigated before pollen assemblages are used to derive the environmental significance in such settings.

  3. Predictability and prediction of summer rainfall in the arid and semi-arid regions of China

    Science.gov (United States)

    Xing, Wen; Wang, Bin

    2016-09-01

    Northwest China (NWC) is an arid and semi-arid region where climate variability and environmental changes are sensitive to precipitation. The present study explores sources and limits of predictability of summer precipitation over NWC using the predictable mode analysis (PMA) of percentage of rainfall anomaly data. Two major modes of NWC summer rainfall variability are identified which are tied to Eurasian continental scale precipitation variations. The first mode features wet northern China corresponding to dry central Siberia and wet Mongolia, which is mainly driven by tropical Pacific sea surface temperature anomalies (SSTA). The second mode features wet western China reflecting wet Central Asia and dry Ural-western Siberia, which strongly links to Indian Ocean SSTA. Anomalous land warming over Eurasia also provides important precursors for the two modes. The cross-validated hindcast results demonstrate these modes can be predicted with significant correlation skills, suggesting that they may be considered as predictable modes. The domain averaged temporal correlation coefficient (TCC) skill during 1979 to 2015 using 0-month (1-month) lead models is 0.39 (0.35), which is considerably higher than dynamical models' multi-model ensemble mean skill (-0.02). Maximum potential attainable prediction skills are also estimated and discussed. The result illustrates advantage of PMA in predicting rainfall over dry land areas and large room for dynamical model improvement. However, secular changes of predictors need to be detected continuously in order to make practical useful prediction.

  4. Aridity modulates N availability in arid and semiarid Mediterranean grasslands.

    Directory of Open Access Journals (Sweden)

    Manuel Delgado-Baquerizo

    Full Text Available While much is known about the factors that control each component of the terrestrial nitrogen (N cycle, it is less clear how these factors affect total N availability, the sum of organic and inorganic forms potentially available to microorganisms and plants. This is particularly true for N-poor ecosystems such as drylands, which are highly sensitive to climate change and desertification processes that can lead to the loss of soil nutrients such as N. We evaluated how different climatic, abiotic, plant and nutrient related factors correlate with N availability in semiarid Stipa tenacissima grasslands along a broad aridity gradient from Spain to Tunisia. Aridity had the strongest relationship with N availability, suggesting the importance of abiotic controls on the N cycle in drylands. Aridity appeared to modulate the effects of pH, plant cover and organic C (OC on N availability. Our results suggest that N transformation rates, which are largely driven by variations in soil moisture, are not the direct drivers of N availability in the studied grasslands. Rather, the strong relationship between aridity and N availability could be driven by indirect effects that operate over long time scales (decades to millennia, including both biotic (e.g. plant cover and abiotic (e.g. soil OC and pH. If these factors are in fact more important than short-term effects of precipitation on N transformation rates, then we might expect to observe a lagged decrease in N availability in response to increasing aridity. Nevertheless, our results suggest that the increase in aridity predicted with ongoing climate change will reduce N availability in the Mediterranean basin, impacting plant nutrient uptake and net primary production in semiarid grasslands throughout this region.

  5. 基于土地利用/覆盖的干旱绿洲区植被覆盖度变化--以新疆生产建设兵团第八师为例%Vegetation change based on land use/cover in arid oasis:A case study of the Eighth Division of Xinjiang Production and Construction Corps

    Institute of Scientific and Technical Information of China (English)

    卢响军; 周益民; 侯秀玲; 李杰; 刘洋; 张殷俊

    2015-01-01

    >cultivated land>grassland>brush land>desert land. Vegetation cover degrees of forest land, brush land, grassland and cultivated land increased respectively by 6.7%, 38.2%, 15.6% and 12.3% from 2000 to 2010. While the areas of land under high vegetation increased, that under low vegetation decreased. 4) Rainfall was the key factor influencing vegetation change in the arid oasis. The findings of this study provided the scientific basis for the protection and management of the ecological environment and planning reasonable production modes in the XPCC region.

  6. Agave Lechuguilla as a Potential Biomass Source in Arid Areas

    Directory of Open Access Journals (Sweden)

    Ahmad Houri

    2016-03-01

    Full Text Available Biomass productivity presents a challenging problem in arid and semi-arid areas.  Despite a large need for energy in the form of solid biomass, liquid fuel or needs for animal feed, these regions remain largely unproductive.  A convenient way to overcome this challenge is to utilize plants with high water-use efficiency.  Agave lechuguilla is an example of a highly productive (3.8 tons ha-1 yr-1 desert plant that holds the potential for producing biomass with minimal water resources.  For this purpose, a global suitability map has been developed showing areas where this plant can be planted, and its productivity was assessed.  A Maxent model was used and was further refined by excluding protected areas and used lands (urban, agriculture, etc...  Productivity assessment provides a good way forward for prioritizing the regional utilization of this plant.   This study provides an initial analysis for the use of arid and semi-arid regions for biomass production.  Results indicate the potential generation of 93.8 million tons per year of dry biomass if the suitable areas were fully utilized.  The analytical method can be readily applied to other potential plant species to optimize the use of certain areas.

  7. To make a land use inventory and its change with time and development. To investigate how this area in the semi-arid climate is developing, and the ecological impact with the construction of several government projects in Central Mexico

    Science.gov (United States)

    Acoustadelcampo, C. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. Comparison between ERTS-1 image scale 1:1,000,000 and CETENAL's charts scale 1:50,000 in irrigated land surface determination in one selected spot gave the following results: Surface on CETENAL's charts 129,900 Has. and arbitrarily we gave 100 percent to this value. Surface on image 122,400 Has., 94.5 percent of the first value. It is necessary to use all four bands to have optimum results on the interpretation. The Principal investigator made use of photointerpretation techniques only, mostly monoscopically.

  8. Désertification des parcours arides au Maroc

    Directory of Open Access Journals (Sweden)

    Mahyou, H.

    2010-01-01

    Full Text Available Desertification of Arid Rangelands in Morocco. Rangeland or natural arid pastures of Morocco are ecosystems where there is a natural or seminatural vegetation composed of steppes, shrubs and grassland. They cover about 82% of the Moroccan arid lands. These areas represent livelihoods for thousands of people and protect the country from desertification. Despite the importance of the rangelands and the threat of desertification, it is surprising that up to date there is no comprehensive assessment of their condition and their evolution, hindering any plan for desertification alleviation. However, the available information on selected pilot areas shows that these rangelands are threatened by desertification. It's associated with biodiversity loss and contributes to climate change. The leading causes of land degradation are the human actions combined with climate. The establishment of a comprehensive surveillance system based on remote sensing, biophysics and socio-economic data must be envisaged to provide policymakers with an operational tool adapted to the spatio-temporal monitoring of desertification.

  9. Stability measures in arid ecosystems

    Science.gov (United States)

    Nosshi, M. I.; Brunsell, N. A.; Koerner, S.

    2015-12-01

    Stability, the capacity of ecosystems to persist in the face of change, has proven its relevance as a fundamental component of ecological theory. Here, we would like to explore meaningful and quantifiable metrics to define stability, with a focus on highly variable arid and semi-arid savanna ecosystems. Recognizing the importance of a characteristic timescale to any definition of stability, our metrics will be focused scales from annual to multi-annual, capturing different aspects of stability. Our three measures of stability, in increasing order of temporal scale, are: (1) Ecosystem resistance, quantified as the degree to which the system maintains its mean state in response to a perturbation (drought), based on inter-annual variability in Normalized Difference Vegetation Index (NDVI). (2) An optimization approach, relevant to arid systems with pulse dynamics, that models vegetation structure and function based on a trade off between the ability to respond to resource availability and avoid stress. (3) Community resilience, measured as species turnover rate (β diversity). Understanding the nature of stability in structurally-diverse arid ecosystems, which are highly variable, yields theoretical insight which has practical implications.

  10. Land use classification in arid region based on multi-seasonal linear spectral mixture analysis and decision tree method%基于多季相光谱混合分解和决策树的干旱区土地利用分类

    Institute of Scientific and Technical Information of China (English)

    姜宛贝; 孙强强; 曲葳; 刘晓娜; 于文婧; 孙丹峰

    2016-01-01

    该文利用2015年Landsat 8多季相数据,以民勤县为例探讨了干旱区土地覆被/利用分类方法。首先进行了研究区多季相遥感数据的主成分变换,确定了Landsat OLI光谱空间的内在维数。其次通过对各季相主成分空间的分析,确定了光谱混合分解的端元类型及各自的代表性季相。获取端元光谱之后,采用全约束线性光谱混合模型分解各个季相的遥感影像,估计各端元组分占像元的面积百分比(端元丰度值)。最后利用端元丰度值的多季相估计结果,依据先验知识和训练样本建立决策树分类规则进行土地覆被/利用分类。分类方法的总体精度达到90.94%,Kappa系数为0.90。研究表明:将物理意义明确的端元丰度值作为分类变量,能够快速、有效地获取分类规则,生成树的结构简单、合理、清晰,对训练数据的依赖性较低,因此具有应用于整个旱地系统土地覆被/利用分类的潜力。%Land-cover/land-cover pattern of arid ecosystem in China, which determines ecosystem service value, is undergoing accelerated changes due to natural and anthropogenic disturbances. To provide a basis for ecosystem service assessment, in this article, we adopted 2015 multi-seasonal data of Landsat 8 for exploring the land cover/use classification method in arid region using the Minqin oasis as a case study area. We firstly conducted a principle component transform on the multi-seasonal remote data for identifying the inherent dimensionality of Landsat OLI spectral space. Then endmember classes and respective representative season were determined through the analysis of principal component feature space for each season. After extracting the endmember spectra by averaging the reflectance of 200~400 endmember pixels, fully-constrained linear spectral mixture model was performed on each seasonal image for yielding quantitative estimates of the areal abundance of

  11. The sensitivity of water availability to aridity changes and other factors - a probabilistic analysis in the Budyko-space

    Science.gov (United States)

    Gudmundsson, Lukas; Greve, Peter

    2016-04-01

    One of the pending questions in the context of global change is (i) whether climatic drivers or (ii) other factors have a stronger influence on water availability. Here we present an idealised approach that allows to estimate the probability that changes in climatological aridity have a larger effect on water availability than other factors. The analysis builds upon a probabilistic extension of the Budyko framework, which is subject to an analytical sensitivity assessment. The results show that changes in water availability are dominated by changes in the aridity index in humid climates. In arid climates other factors are dominating. A global application predicts only little influence of aridity changes on water availability in drylands. This implies that the projected intensification of aridity in dry regions may have less influence on water availability than commonly assumed. Instead other factors, including e.g. land use change, are likely dominating.

  12. Annual plants in arid and semi-arid desert regions

    Institute of Scientific and Technical Information of China (English)

    Xuehua LI; Xiaolan LI; Deming JIANG; Zhimin LIU; Qinghe YU

    2008-01-01

    Annual plants are the main vegetation in arid and semi-arid desert regions.Because of their unique traits,they are the optimal experimental subjects for eco-logical studies.In this article,we summarize annual plants' seed germination strategies,seedling adaptability mechanism to environments,seed dispersal,and soil seed banks.We also discuss the biotic and abiotic factors affecting the composition and dynamics of annual plant populations and communities.Because annual plants have important ecological functions in desert vegetation systems,this study on annual plants will be of great bene-fit to the conservation and restoration of desert ecosys-tems,the rational utilization of resources,and the sustainable development of desert regions.

  13. Study on retrieval model of land surface temperature in Jinghe watershed in arid region%干旱区精河流域地表温度的模型反演研究

    Institute of Scientific and Technical Information of China (English)

    王明霞; 毋兆鹏

    2014-01-01

    Based on Landsat ETM+ image data in Jinghe watershed oasis ,both methods of mono-window algorithm and single-channel algorithm were adopted to retrieve land surface temperature (LST ) in the study area ,and the compari-son between the retrieved results and MODIS temperature products (MODIS LST ) was made .The results showed :(1 ) The retrieved results from these two algorithms were similar each other in overall trend ,and the mean temperature differ-ence of the whole study area was about 2k .(2) The retrieval accuracy could be improved effectively by using modified soil-adjusted vegetation index (MSAVI ) instead of normalized differential vegetation index (NDVI ) to compute land sur-face emissivity ,and the retrieval accuracy of single-window algorithm was higher than that of single-channel algorithm . The correlation coefficients between the retrieved data of these two algorithms and MODIS LST were 0 .925 and 0 .8651 , respectively .(3) In the urban areas ,the correlation coefficient between the retrieved data of single-channel algorithm and MSAVI was 0 .8136 ,being higher than that of mono-window algorithm .Therefore ,the method of single-channel al-gorithm was more suitable for the retrieval research of LST in urban areas in large scale .%以精河流域绿洲为研究区,使用Landsat ETM+数据,采用单窗算法和普适性单通道算法对研究区地表温度进行反演,并将这两种算法的反演结果与研究区MODIS温度产品(MODIS LST )进行比较。结果表明:(1)单窗算法和普适性单通道算法反演的结果总体趋势比较接近,研究区整体的平均温度相差约2k;(2)采用改进型土壤调整植被指数(MSAVI )代替归一植被指数(NDVI )计算地表比辐射率可有效提高反演精度,并且同等条件下单窗算法的反演精度高于普适性单通道算法,两种算法的反演结果与MODIS LST的相关系数分别是0.9255和0.8651;(3)在城镇区域,普适

  14. 基于C5.0决策树算法的西北干旱区土地覆盖分类研究——以甘肃省武威市为例%The Study of the Northwest Arid Zone Land-Cover Classification Based on C5.0 Decision Tree Algorithm at Wuwei City,Gansu Province

    Institute of Scientific and Technical Information of China (English)

    齐红超; 祁元; 徐瑱

    2009-01-01

    西北干旱区面积广阔,由于土地利用类型多样,成因复杂,对环境变化敏感、变化过程快、幅度大、景观差异明显等特点,在影像上表现出的"同物异谱"现象明显;利用常规目视解译、监督非监督分类、人工参与的决策树分类等方法在效率或精度等方面各有其缺陷.采用机器学习C5.0决策树算法,综合利用地物波谱、NDVI、TC、纹理等信息,根据样本数据自动挖掘分类规则并对整个研究区进行地物分类.机器学习的决策树可以挖掘出更多的分类规则,C5.0算法对采样数据的分布没有要求,可以处理离散和连续数据,生成的规则易于理解,分类精度高,可以满足西北干旱区大面积的土地利用/覆被变化制图的需要.%In the broadly northwest arid regions,frequently,same object has different spectral characters because of the special characteristics of land cover change such as complex causes of formation,sensitivity to environment change,rapid and violent change and obvious differences in landscape. The conventional methods of classification including visual interpretation,supervised classification,unsupervised classification,and artificial decision tree classification have disadvantages in the efficiency or the accuracy. In this paper,machine learning algorithm based on C5. 0 decision tree was used to classify the entire study area automatically according to the sample data mining classification rules. Spectral features,NDVI,TC,texture and other informations were involved in the algorithm. More classification rules could be mined by machine learning decision tree. C5. 0 algorithm handling with both continuous and discrete data is independent of the distribution of sampling sites,The classification rules mined by this algorithm were interpretable. Other superiority of this algorithm included the fast speed of training and higher accuracy than many other classifiers. Thus,it is able to be used in the mapping of

  15. Conservation tillage systems and water productivity implications for smallholder farmers in semi-arid Ethiopia

    NARCIS (Netherlands)

    Temesgen, M.L.

    2007-01-01

    Conservation tillage systems have been adopted by farmers in many countries to solve the problem of land degradation and declining water productivity. However, direct application of such tillage systems was not possible among resource poor smallholder farmers in semi arid areas of Ethiopia. Problems

  16. Runoff controlling factors in various sized catchments in a semi-arid Mediterranean environment in Spain

    NARCIS (Netherlands)

    Wit, A.M.W. de

    2001-01-01

    Understanding land degradation in a semi-arid Mediterranean environment is very difficult because of the contributing factors: precipitation, infiltration vegetation cover and discontinuity of flow and the temporal and spatial levels of resolution at which these factors are acting. Therefore it is s

  17. Genomic dissection of genotype x environment interactions conferring adaptation of cotton to arid conditions.

    Science.gov (United States)

    Saranga, Y; Menz, M; Jiang, C X; Wright, R J; Yakir, D; Paterson, A H

    2001-12-01

    The interaction of genotype with environment is of primary importance in many aspects of genomic research and is a special priority in the study of major crops grown in a wide range of environments. Water deficit, the major factor limiting plant growth and crop productivity worldwide, is expected to increase with the spread of arid lands. In genetically equivalent cotton populations grown under well-watered and water-limited conditions (the latter is responsible for yield reduction of approximately 50% relative to well-watered conditions), productivity and quality were shown to be partly accounted for by different quantitative trait loci (QTLs), indicating that adaptation to both arid and favorable conditions can be combined in the same genotype. QTL mapping was also used to test the association between productivity and quality under water deficit with a suite of traits often found to differ between genotypes adapted to arid versus well-watered conditions. In this study, only reduced plant osmotic potential was clearly implicated in improved cotton productivity under arid conditions. Genomic tools and approaches may expedite breeding of genotypes that respond favorably to specific environments, help test roles of additional physiological factors, and guide the isolation of genes that protect crop performance under arid conditions toward improved adaptation of crops to arid cultivation.

  18. Propágulos de fungos micorrízicos arbusculares em solos deficientes em fósforo sob diferentes usos, da região semi-arida no nordeste do Brasil Propagules of arbuscular mycorrhizae in p-deficient soils under different land uses, in semi-arid NE Brazil

    Directory of Open Access Journals (Sweden)

    Regina Lúcia Félix de Aguiar Lima

    2007-04-01

    Full Text Available A conversão de áreas de caatinga em agricultura e pecuária de subsistência é uma das características marcantes da região semi-árida do Nordeste do Brasil. O presente estudo investigou o efeito dessa conversão sobre os propágulos de fungos micorrízicos arbusculares (FMA em 10 locais diferentes, distribuídos nos Estados da Paraíba e de Pernambuco. Cada local consistiu de uma área de vegetação nativa (caatinga contígua com uma área cultivada, na mesma posição de encosta. Amostras de solo foram coletadas a intervalos de 20-30 m, nas profundidades de 0-7,5 e 7,5-15 cm (10 locais x 2 usos do solo x 2 profundidades com 4 pontos amostrais ao longo de uma transecção que cruzava as áreas contíguas. As raízes (The conversion of tropical dry forest into areas used for subsistence agriculture or livestock production is a common feature of the semi-arid region of NE Brazil. Our study looked into the effect of these land use changes on propagules of arbuscular mycorrhizal fungi (AMF at ten sites distributed in the states of Paraíba and Pernambuco. Each site consisted of an area under native vegetation (Dry-Forest adjacent to a cultivated area in the same slope position. Soil samples were taken at distance intervals of 20-30 m from two depths (0-7.5 and 7.5-15 cm along a transect crossing the adjacent areas (10 sites x 2 land uses x 2 depths x 4 sampling points. Roots (< 2 mm found in the soil samples (n = 160 were stained with trypan blue to assess the percentage of AMF colonization as well as the type of fungal structures. The AMF spores were separated from soil by wet sieving, incubated in iodonitrotetrazolium chloride (INT solution and counted; those stained with INT were considered viable. Soil samples were analyzed for resin-extractable P and total organic carbon (TOC. For data analysis, the 10 areas under dry forest were separated in two sub-groups: Undisturbed-Dry-Forest (UDF, n = 6 and Disturbed-Dry-Forest (DDF, n = 4, owing

  19. Estimation of soil moisture-thermal infrared emissivity relation in arid and semi-arid environments using satellite observations

    Science.gov (United States)

    Grazia Blasi, Maria; Masiello, Guido; Serio, Carmine; Venafra, Sara; Liuzzi, Giuliano; Dini, Luigi

    2016-04-01

    The retrieval of surface parameters is very important for various aspects concerning the climatological and meteorological context. At this purpose surface emissivity represents one of the most important parameters useful for different applications such as the estimation of climate changes and land cover features. It is known that thermal infrared (TIR) emissivity is affected by soil moisture, but there are very few works in literature on this issue. This study is aimed to analyze and find a relation between satellite soil moisture data and TIR emissivity focusing on arid and semi-arid environments. These two parameters, together with the land surface temperature, are fundamental for a better understanding of the physical phenomena implied in the soil-atmosphere interactions and the surface energy balance. They are also important in several fields of study, such as climatology, meteorology, hydrology and agriculture. In particular, there are several studies stating a correlation between soil moisture and the emissivity at 8-9 μm in desertic soils, which corresponds to the quartz Reststrahlen, a feature which is typical of sandy soils. We investigated several areas characterized by arid or semi-arid environments, focusing our attention on the Dahra desert (Senegal), and on the Negev desert (Israel). For the Dahra desert we considered both in situ, provided by the International Soil Moisture Network, and satellite soil moisture data, from ASCAT and AMSR-E sensors, for the whole year 2011. In the case of the Negev desert soil moisture data are derived from ASCAT observations and we computed a soil moisture index from a temporal series of SAR data acquired by the Cosmo-SkyMed constellation covering a period of six months, from June 2015 to November 2015. For both cases soil moisture data were related to the retrieved TIR emissivity from the geostationary satellite SEVIRI in three different spectral channels, at 8.7 μm, 10.8 μm and 12 μm. A Kalman filter physical

  20. Dynamics in carbon exchange fluxes for a grazed semi-arid savanna ecosystem in West Africa

    DEFF Research Database (Denmark)

    Tagesson, Torbern; Fensholt, Rasmus; Cropley, Ford;

    2015-01-01

    The main aim of this paper is to study land-atmosphere exchange of carbon dioxide (CO2) for semi-arid savanna ecosystems of the Sahel region and its response to climatic and environmental change. A subsidiary aim is to study and quantify the seasonal dynamics in light use efficiency (ε) being a key...... variable in scaling carbon fluxes from ground observations using earth observation data. The net ecosystem exchange of carbon dioxide (NEE) 2010-2013 was measured using the eddy covariance technique at a grazed semi-arid savanna site in Senegal, West Africa. Night-time NEE was not related to temperature...

  1. Recommended Species for Vegetative Stabilization of Training Lands in Arid and Semi-Arid Environments

    Science.gov (United States)

    1985-09-01

    semibacata Awnless bush sunflower Helianthus sp. Bahia grass Paspalum notatum Barley Hordeum vulgare Basin wildrye Elymus cinereus Bearded wheatgrass...Boer lovegrass Eragrostis curvuLa *Brittlebush Encelia farinosa *Brome grasses Bromus spp. Buckwheat s Eriogonum spp. Buffalograss Buchloe dactyloides...mexicana *Millets Panicum spp. Mountain brome Bromus montanum Mountain mahogany Gercocarpus montanus *Mountain penstenion Penstemon montanus *Muhly grasses

  2. Agricultural sustainability in the semi-arid Near East

    Directory of Open Access Journals (Sweden)

    F. Hole

    2007-05-01

    Full Text Available Agriculture began in the eastern Mediterranean Levantine Corridor about 11000 years ago toward the end of the Younger Dryas when aridity had diminished wild food resources. During the subsequent Climatic Optimum, agricultural villages spread rapidly but subsequent climatic changes on centennial to millennial scales resulted in striking oscillations in settlement, especially in marginal areas. Natural climate change thus alternately enhanced and diminished the agricultural potential of the land. Growing populations and more intensive land us, both for agriculture and livestock, have led to changes in the structure of vegetation, hydrology, and land quality. Over the millennia, political and economic interventions, warfare and incursions by nomadic herding tribes all impacted sustainability of agriculture and the ability of the land to supports its populations. In much of the region today, agricultural land use is not sustainable given existing technology and national priorities. The Near Eastern case is instructive because of the quality of information, the length of the record, and the pace of modern change.

  3. Agricultural sustainability in the semi-arid Near East

    Directory of Open Access Journals (Sweden)

    F. Hole

    2006-07-01

    Full Text Available Agriculture began in the eastern Mediterranean Levantine Corridor about 11 000 years ago toward the end of the Younger Dryas when aridity had diminished wild food resources. During the subsequent Climatic Optimum, agricultural villages spread rapidly but subsequent climatic changes on centennial to millennial scales resulted in striking oscillations in settlement, especially in marginal areas. Natural climate change thus alternately enhanced and diminished the agricultural potential of the land. Growing populations and more intensive land use, both for agriculture and livestock, have led to changes in the structure of vegetation, hydrology, and land quality. Over the millennia, political and economic interventions, warfare and incursions by nomadic herding tribes all impacted sustainability of agriculture and the ability of the land to support its populations. In much of the region today, agricultural land use is not sustainable given existing technology and national priorities. The Near Eastern case is instructive because of the quality of information, the length of the record, and the pace of modern change.

  4. New Technologies to Reclaim Arid Lands User’s Manual

    Science.gov (United States)

    2002-10-01

    microbiota of the recovered soil and has been used effectively to jump start revegetation (Winkel et al., 1999). Site preparation may include...in order to successfully germinate (Figure 3-7). Examples of safe sites include properly buried seed, seed in depressions that collect additional... depressions is much better than a smooth level seedbed because a rough seedbed provides many more "safe sites," which results in increased seed

  5. Combating desertification strategies in arid land of India

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, K. N.; Solanki, S. S.

    2009-07-01

    The present study deals with the current status and process of desertification due to over exploitation and mis-management of natural resources of the Rajasthan. The author try to make some observations on specific indicators of natural resources degradation that have strong impact on the process of desertification. The author have also looked into the climatological phenomenon such as drough. From the above study it is very much clear that the meet out the ever increasing demand of the man and society, the natural resources are being exploited at the rate where no regeneration is possible. Lastly, a brief account of the protective measures that have been taken by government is discussed. (Author)

  6. 覆膜方式对旱地糜子生育后期干物质积累与转运的影响%Effects of Film Mulching Modes on Dry Matter Accumulation and Transportation Characteristics of Broomcorn Millet at Later Growing Stage in Arid Land

    Institute of Scientific and Technical Information of China (English)

    张盼盼; 冯乃杰; 郑殿峰; 柯希望; 金喜军; 殷丽华; 刘洋; 刘涛; 石英; 张洪鹏; 马爽

    2015-01-01

    The variety of Jinshu 7 was used as material to study the effects of film mulching modes on dry matter accumulation and transportation characteristics of broomcorn millet at later growing stage in arid land. The results showed that it compared with traditional planting,and the above-ground dry matter accumulation of film side dibble and flat film dibble increased by 55.56%, 27.88%,and seed dry matter increased by 9.25%,24.90% in the whole grain filling periods. Film mulching can contributed to the transportation of dry matter of vegetative organs to grains. The contribution to grain yield of stem was bigger than those of leaf and sheath,which was as high as 55.31%-56.08%. Film mulching had the obvious role in promoting grain number per plant and 1000-grain weight. Compared with traditional planting,the yield of film side dibble and flat film dibble increased by 40.52%and 51.2%, respectively,Which indicated that the effect of film side dibble to dry matter accumulation and transportation was better than film dibbling so as to increas grain yield in broomcorn millet.%以晋黍7号为材料,研究旱地不同覆膜方式对糜子生育后期干物质积累与转运的影响。试验结果表明,整个籽粒灌浆期,与露地条播相比,膜侧穴播、平膜穴播地上干物质的积累量分别增加55.56%、27.88%,籽粒干重分别提高9.25%、24.90%。覆膜能够促进花后营养器官干物质向籽粒中转运,茎干物质对籽粒的贡献率高于叶、鞘,其贡献率高达55.31%~56.08%。覆膜处理对糜子单株粒数、千粒重有明显的促进作用;膜侧穴播、平膜穴播分别比露地条播增产40.52%、51.2%,说明膜侧穴播对糜子干物质积累与转运的促进效果优于平膜穴播,有利于糜子产量的提高。

  7. 干旱年份播期对旱地冬小麦产量及水分利用效率的影响%Effect of sowing date on yield and water use efficiency of winter wheat on dry land in arid year

    Institute of Scientific and Technical Information of China (English)

    党建友; 王姣爱; 张晶; 曹勇; 张建华; 卫云宗; 张定一

    2011-01-01

    通过田间大区试验研究了干旱年份播期对旱地小麦生长发育、籽粒产量和水分利用效率的影响.结果表明,9月30日播种,分蘖成穗率高,群体合理,灌浆前中期旗叶叶绿素SPAD相对值最高,上三叶总干物质转移量和总转移率居中,快、缓增期籽粒灌浆持续时间T2和T3最长,灌浆平均速率最高,成穗数最多,千粒重最高,籽粒产量最高,达2 623.3 kg/hm2,分别较9月20日和10月5日播种增产84.48%和10.11%;9月30日播种,生育期耗水量居中,籽粒水分生产率最高,达0.979 kg/mm.因此,临汾市尧都区旱地小麦播期适当推迟到9月30日左右,可提高自然降水生产效率,实现高产高效.%Effect of sowing date on growth, grain yield, water use efficiency(WUE) of winter wheat on dry land in arid years was investigated through field experiment. The results showed that wheat sowing on September 30 could get high tillering and high panicle rate and rational groups. Furthermore, it had high SPAD value of flag leaves, big leaf areas of upper three leaves, and total transfer amount and total transfer rate during early and middle filling stage were between other sowing dates. It could also keep the longest filling period of fast and slowly increasing stages( T2, T3), and the highest average filling rate(R). All of these led to the most panicles, the highest 1000-kernel weight, and the highest grain yield of 2 623.3 kg/hm2, which was 84.48 % and 10.11% higher than the wheat sowing at September 20 and October 5, respectively. When sowing on September 30, the water consumption of wheat during growth stage was between those with other sowing dates, and WUE of grain was 0.979 kg/mm, which was the highest.

  8. On the Role of Hyper-arid Regions within the Virtual Water Trade Network

    Science.gov (United States)

    Aggrey, James; Alshamsi, Aamena; Molini, Annalisa

    2016-04-01

    Climate change, economic development, and population growth are bound to increasingly impact global water resources, posing a significant threat to the sustainable development of arid regions, where water consumption highly exceeds the natural carrying capacity, population growth rate is high, and climate variability is going to impact both water consumption and availability. Virtual Water Trade (VWT) - i.e. the international trade network of water-intensive products - has been proposed as a possible solution to optimize the allocation of water resources on the global scale. By increasing food availability and lowering food prices it may in fact help the rapid development of water-scarce regions. The structure of the VWT network has been analyzed by a number of authors both in connection with trade policies, socioeconomic constrains and agricultural efficiency. However a systematic analysis of the structure and the dynamics of the VWT network conditional to aridity, climatic forcing and energy availability, is still missing. Our goal is hence to analyze the role of arid and hyper-arid regions within the VWN under diverse climatic, demographic, and energy constraints with an aim to contribute to the ongoing Energy-Water-Food nexus discussion. In particular, we focus on the hyper-arid lands of the Arabian Peninsula, the role they play in the global network and the assessment of their specific criticalities, as reflected in the VWN resilience.

  9. Modeling carbon cycle dynamics and response to drought in semi-arid ecosystems

    Science.gov (United States)

    Hilton, T. W.; Fox, A. M.; Krofcheck, D. J.; Litvak, M. E.

    2012-12-01

    The southwestern United States is presently experiencing a multi-year drought. Though the carbon uptake per unit area of the semi-arid biomes in this region is smaller than that of more temperate biomes, these biomes cover roughly 40 percent of the world's land surface, and thus make a significant contribution to the global terrestrial biological carbon cycle. Here we test the ability of two land surface model structures to diagnose the carbon cycle dynamics of semi-arid landscapes during the ongoing extreme drought. We use the New Mexico Elevation Gradient (NMEG) as a testbed for these modeling experiments. The NMEG comprises eight eddy covariance towers observing ecosystems ranging from desert grassland ( 1600 m elevation) to alpine mixed coniferous forest ( 3000 m elevation). During the drought the ecosystems observed by these towers saw their annual net carbon uptake decline between 33 and 100 percent (50 to 150 gC m^{-2} year^{-1}), with two of the eight sites becoming net sources of carbon to the atmosphere and one transitioning from a net carbon sink to carbon-neutral. We parametrize a simple light-use efficiency (LUE)-based model (Vegetation Photosynthesis and Respiration Model, VPRM) and a complex model which simulates many land surface processes (Community Land Model, CLM). We explore the capacity of both models to diagnose the terrestrial carbon cycle in semi-arid biomes where water availability is highly episodic.

  10. Remote sensing of threshold conditions in an arid ecosystem

    Science.gov (United States)

    Steele, C. M.; Bestelmeyer, B. T.; Rango, A.; Smith, P. L.; Laliberte, A. S.

    2007-12-01

    Land management in the arid southwestern USA increasingly addresses thresholds in response to recent concepts adopted by private and public lands agencies and conservation organizations. Vegetation in arid rangelands typically presents as distinctive mosaics of vegetation patches, which persist in dynamic equilibrium with the abiotic environment and facilitative-competitive interactions between organisms. Theory and observation suggest that as an area approaches a threshold in response to disturbance, there is a concomitant change in the spatial arrangement of vegetation patches. This change is readily identifiable on fine spatial resolution aerial photography or satellite sensor imagery. We propose a classification method for identifying threshold-inducing change in vegetation pattern. To illustrate this method, we have applied an object-oriented, supervised classification to subsets of Quickbird imagery (70 cm ground resolution) over the Jornada basin in southern New Mexico. The imagery covers several land management regimes (private, public, federal) and provides spatial variation in ecosystem conditions. Imagery was first segmented to create fine and coarse resolution image objects. Fine resolution image objects are defined as having within-object spectral homogeneity at the scale of the shrub or single patch of grass or soil. Coarse resolution image objects are defined as containing spectral homogeneity at the scale of the vegetation stand. A classification tree was used to classify coarse resolution image objects to high risk of a threshold, low risk of a threshold, or post-threshold according to the content and spatial arrangement of shrub, grass and soil patches within them. Ground-based monitoring to detect localized threshold conditions across broad management areas is intractable so the use of remote sensing is essential to successful prevention of threshold development.

  11. Evaluating the Potential of PROBA-V Satellite Image Time Series for Improving LC Classification in Semi-Arid African Landscapes

    NARCIS (Netherlands)

    Eberenz, Johannes; Verbesselt, Jan; Herold, Martin; Tsendbazar, Nandika; Sabatino, Giovanni; Rivolta, Giancarlo

    2016-01-01

    Satellite based land cover classification for Africa’s semi-arid ecosystems is hampered commonly by heterogeneous landscapes with mixed vegetation and small scale land use. Higher spatial resolution remote sensing time series data can improve classification results under these difficult conditions.

  12. Agave: a biofuel feedstock for arid and semi-arid environments

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Stephen; Martin, Jeffrey; Simpson, June; Wang, Zhong; Visel, Axel

    2011-05-31

    Efficient production of plant-based, lignocellulosic biofuels relies upon continued improvement of existing biofuel feedstock species, as well as the introduction of newfeedstocks capable of growing on marginal lands to avoid conflicts with existing food production and minimize use of water and nitrogen resources. To this end, specieswithin the plant genus Agave have recently been proposed as new biofuel feedstocks. Many Agave species are adapted to hot and arid environments generally unsuitable forfood production, yet have biomass productivity rates comparable to other second-generation biofuel feedstocks such as switchgrass and Miscanthus. Agavesachieve remarkable heat tolerance and water use efficiency in part through a Crassulacean Acid Metabolism (CAM) mode of photosynthesis, but the genes andregulatory pathways enabling CAM and thermotolerance in agaves remain poorly understood. We seek to accelerate the development of agave as a new biofuelfeedstock through genomic approaches using massively-parallel sequencing technologies. First, we plan to sequence the transcriptome of A. tequilana to provide adatabase of protein-coding genes to the agave research community. Second, we will compare transcriptome-wide gene expression of agaves under different environmentalconditions in order to understand genetic pathways controlling CAM, water use efficiency, and thermotolerance. Finally, we aim to compare the transcriptome of A.tequilana with that of other Agave species to gain further insight into molecular mechanisms underlying traits desirable for biofuel feedstocks. These genomicapproaches will provide sequence and gene expression information critical to the breeding and domestication of Agave species suitable for biofuel production.

  13. SCIENCES IN COLD AND ARID REGIONS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Aims and Scope Sciences in Cold and Arid Regions, an international Engiish-language journal, is devoted to publishing the latest research achievements on the process and the pattern of Earth surface system in cold and arid regions. Researches in cold regions 1) emphasize particularly on the cold-region-characterized physical, chemical and biological processes and their interactions, and on the response of Cryosphere to Global change and Human activities as well as its effect to environment and the acclimatizable

  14. The Role of Moisture in the Successful Rehabilitation of Denuded Patches of a Semi-Arid Environment in Kenya

    NARCIS (Netherlands)

    Mganga, K.Z.; Musimba, N.; Nyangito, M.M.; Musimba, N.K.R.; Mwangombe, A.W.; Ekaya, W.N.; Muiri, W.M.; Clavel, D.; Francis, J.; Kaufman, Von R.; Verhagen, A.

    2011-01-01

    This study investigated the role of moisture in the successful rehabilitation of denuded patches in semi-arid lands of Kenya and the primary productivity of three perennial rangelands grasses namely Cenchrus ciliaris (African foxtail), Enteropogon macrostachyus (Bush rye) and Eragrostis superba (Maa

  15. Aridity, desalination plants and tourism in the eastern Canary Islands

    Directory of Open Access Journals (Sweden)

    José-León García-Rodríguez

    2016-05-01

    Full Text Available The islands of Lanzarote and Fuerteventura are the easternmost of the Canary Islands, and are located on the southern edge of the temperate zone, in the subtropical anticyclone belt. With less than 150 mm of rainfall a year, they are classified as an arid zone. Their inhabitants have devised original agricultural systems to combat the aridity, although low yields have historically limited socio-economic development and population growth. These systems were used until the introduction of seawater desalination plants and the arrival of tourism in the last third of the twentieth century, which improved living standards for the local population but also led to a cultural transition. Nevertheless, these farming systems have left behind an important regional heritage, with an environmental and scenic value that has played an integral role in the latest phase of development. The systems have become a tourist attraction and have been central to the two islands being designated biosphere reserves by UNESCO. This article aims to analyse the main socioeconomic and land-use changes that have come about as a result of desalination technology.

  16. Análise espaço-temporal do uso da terra em parte do semi-árido cearense Spatial and temporal-time analysis of land use in part of the semi-arid region of Ceará State, Brazil

    Directory of Open Access Journals (Sweden)

    J. B. Andrade

    2004-04-01

    Full Text Available A cobertura vegetal exerce papel imprescindível à proteção e conservação dos recursos naturais, principalmente no que diz respeito aos solos. Este estudo teve como objetivo avaliar e analisar a dimensão espacial e temporal da ação antrópica na cobertura vegetal de parte do semi-árido cearense, utilizando imagens LANDSAT TM-5, de 1985 e 1994, e técnicas de geoprocessamento, para verificar a hipótese de que a degradação ambiental vem sendo intensificada. Foram confeccionadas cartas de vegetação, uso da terra, solos e hidrografia, obtendo-se cartas de sobreposição, por meio das quais se constatou o aumento de áreas degradadas nas diferentes unidades fitoecológicas. No período de uma década, comprovou-se o processo progressivo da degradação nas áreas dos municípios de Independência, Pedra Branca, Mombaça e Tauá, tendo as áreas do município de Pedra Branca apresentado menor degradação. A unidade fitoecológica mais degradada, dentre as estudadas, foi a Caatinga Arbórea Aberta, desencadeando processos de degradação e transformação das unidades circunvizinhas. Grande parte da área foi atingida por processos de degradação ambiental, com forte pauperização da biodiversidade, acompanhados por um rebaixamento geral das formações vegetais.The vegetation cover plays a key role in protection and conservation of natural resources, particularly concerning soils. This study had as objective to analyze space and time dimensions of anthropic influence on the vegetation cover in part of the semi-arid region of the Ceará State, Brazil. LANDSAT TM-5 satellite images of 1985 and 1994 combined with geoprocessing techniques were used to verify the hypothesis of intensification of environmental degradation. Maps of the vegetation cover, land use, soils, and hydrography were elaborated. They pointed out to an increase in degraded areas of the different phytoecological units. During this decade, a progressive degradation

  17. Structure Optimization of Urban Industy in Arid Land Based on Water Footprint:A Case Study of Urumqi%水足迹视角下干旱区城市工业结构优化研究--以乌鲁木齐市为例

    Institute of Scientific and Technical Information of China (English)

    李啸虎; 杨德刚

    2015-01-01

    The development of urban industry in arid lands is constrained by the severe contradiction between the supply of available water and the demand for water resources, as well as increasing water pollution. We calculated the water consumption of industrial sectors from the perspective of their water footprints, and optimized the industrial structure to achieve the goals of water conservation and reduction of water pollution. These are of great significance to guarantee sustainable urban development in arid lands. In this study, we generated industrial water footprint (WFi), and multi-objective programming(MOP) models based on the concept of water footprint. Then we selected Urumqi as a case study, and estimated the water consumption of its industrial sectors using the WFi model. Based on this, we performed a cluster analysis of the industrial sectors. Finally, based on the cluster results and the industrial development plan for Urumqi, we examined the program for future industrial development using the MOP model. This study revealed the following. ①Based on the industrial added value, as well as blue and grey footprints of every industrial sector, we divided the industrial sectors into four categories. These were sectors with strong economic contribution, high water consumption, and much pollution; sectors with strong economic contribution, low water consumption, and little pollution; sectors with weak economic contribution, low water consumption, and little pollution;and sectors with weak economic contribution, high water consumption, and much pollution. ② On this basis, using the MOP model, we selected the sustainable mode as the best future program for industrial development in Urumqi. According to it, the WFi would be 3. 13×108 m3 in Urumqi in 2015, and assumes that the industrial blue water footprint would be 0. 72×108 m3 and the industrial grey water footprint would be 2. 41×108 m3. Industrial output value and added value would be 2. 34×1011RMB Yuan,1

  18. Rainwater harvesting in arid and semi-arid zones (repr. 1997)

    NARCIS (Netherlands)

    Boers, Th.M.

    1994-01-01

    In arid and semi-arid regions, the scarcity of water can be alleviated by rainwater harvesting, which is defined as a method of inducing, collecting, storing, and conserving local surface runoff for agriculture. Rainwater harvesting can be applied with different systems, and this dissertation deals

  19. Risk of fire occurrence in arid and semi-arid ecosystems of Iran: an investigation using Bayesian belief networks.

    Science.gov (United States)

    Bashari, Hossein; Naghipour, Ali Asghar; Khajeddin, Seyed Jamaleddin; Sangoony, Hamed; Tahmasebi, Pejman

    2016-09-01

    Identifying areas that have a high risk of burning is a main component of fire management planning. Although the available tools can predict the fire risks, these are poor in accommodating uncertainties in their predictions. In this study, we accommodated uncertainty in wildfire prediction using Bayesian belief networks (BBNs). An influence diagram was developed to identify the factors influencing wildfire in arid and semi-arid areas of Iran, and it was populated with probabilities to produce a BBNs model. The behavior of the model was tested using scenario and sensitivity analysis. Land cover/use, mean annual rainfall, mean annual temperature, elevation, and livestock density were recognized as the main variables determining wildfire occurrence. The produced model had good accuracy as its ROC area under the curve was 0.986. The model could be applied in both predictive and diagnostic analysis for answering "what if" and "how" questions. The probabilistic relationships within the model can be updated over time using observation and monitoring data. The wildfire BBN model may be updated as new knowledge emerges; hence, it can be used to support the process of adaptive management.

  20. Algae from the arid southwestern United States: an annotated bibliography

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, W.H.; Gaines, S.R.

    1983-06-01

    Desert algae are attractive biomass producers for capturing solar energy through photosynthesis of organic matter. They are probably capable of higher yields and efficiencies of light utilization than higher plants, and are already adapted to extremes of sunlight intensity, salinity and temperature such as are found in the desert. This report consists of an annotated bibliography of the literature on algae from the arid southwestern United States. It was prepared in anticipation of efforts to isolate desert algae and study their yields in the laboratory. These steps are necessary prior to setting up outdoor algal culture ponds. Desert areas are attractive for such applications because land, sunlight, and, to some extent, water resources are abundant there. References are sorted by state.

  1. An Overview of Biodegradation of LNAPLs in Coastal (Semi)-arid Environment.

    KAUST Repository

    Yadav, Brijesh Kumar

    2011-02-22

    Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these organic contaminated resources is receiving increasing interests and where applicable, can serve as a cost-effective remediation alternative. The success of bioremediation greatly depends on the prevailing environmental variables, and their remediation favoring customization requires a sound understanding of their integrated behavior on fate and transport of LNAPLs under site-specific conditions. The arid and semi-arid coastal sites are characterized by specific environmental extremes; primarily, varying low and high temperatures, high salinity, water table dynamics, and fluctuating soil moisture content. An understanding of the behavior of these environmental variables on biological interactions with LNAPLs would be helpful in customizing the bioremediation for restoring problematic sites in these regions. Therefore, this paper reviews the microbial degradation of LNAPLs in soil-water, considering the influences of prevailing environmental parameters of arid and semi-arid coastal regions. First, the mechanism of biodegradation of LNAPLs is discussed briefly, followed by a summary of popular kinetic models used by researchers for describing the degradation rate of these hydrocarbons. Next, the impact of soil moisture content, water table dynamics, and soil-water temperature on the fate and transport of LNAPLs are discussed, including an overview of the studies conducted so far. Finally, based on the reviewed information, a general conclusion is presented with recommendations for future research subjects on optimizing the bioremediation technique in the field under the aforesaid environmental conditions. The present review will be useful to better understand the

  2. Great Basin semi-arid woodland dynamics during the late quaternary

    Energy Technology Data Exchange (ETDEWEB)

    Wigand, P.E.; Hemphill, M.L.; Sharpe, S.E. [Univ. and Community College System of Nevada, Reno, NV (United States)] [and others

    1995-09-01

    Semi-arid woodlands have dominated the middle elevations of Great Basin mountain ranges during the Holocene where subalpine woodlands prevailed during the Pleistocene. Ancient woodrat middens, and in a few cases pollen records indicate in the late Pleistocene and early Holocene woodland history lowered elevation of subalpine woodland species. After a middle Holocene retrenchment at elevations in excess of 500 meters above today, Juniper-dominated semi-arid woodland reached its late Holocene maximum areal extent during the Neoglacial (2 to 4 ka). These records, along with others indicate contracting semi-arid woodland after the Neoglacial about 1.9 ka. Desert shrub community expansion coupled with increased precariousness of wetland areas in the southern Great Basin between 1.9 and 1.5 ka coincide with shrinking wet-lands in the west-central and northern Great Basin. Coincident greater grass abundance in northern Great Basin sagebrush steppe, reaching its maximum between 1.5 and 1.2 ka, corresponds to dramatic increases in bison remains in the archaeological sites of the northern Intermontane West. Pollen and woodrat midden records indicate that this drought ended about 1.5 ka. Succeeding ameliorating conditions resulted in the sudden northward and downward expansion of pinon into areas that had been dominated by juniper during the Neoglacial. Maximum areal extent of pinon dominated semi-arid woodland in west-central Nevada was centered at 1.2 ka. This followed by 100 years the shift in dominance from juniper to pinon in southern Nevada semi-arid woodlands. Great Basin woodlands suffered from renewed severe droughts between .5 to .6 ka. Effectively wetter conditions during the {open_quotes}Little Ice Age{close_quotes} resulted in re-expansion of semi-arid woodland. Activities related to European settlement in the Great Basin have modified prehistoric factors or imposed new ones that are affecting woodland response to climate.

  3. Soil moisture and vegetation memories in a cold, arid climate

    Science.gov (United States)

    Shinoda, Masato; Nandintsetseg, Banzragch

    2011-10-01

    Continental climate is established as a result of a complex interplay between the atmosphere and various land-surface systems such as the biosphere, soil, hydrosphere, and cryosphere. These systems function as climate memory, allowing the maintenance of interannual atmospheric anomalies. In this paper, we present new observational evidence of an interseasonal moisture memory mechanism mediated by the land surface that is manifested in the coupled cold and arid climate of Mongolia. Interannual anomalies of soil moisture and vegetation due to rainfall during a given summer are maintained through the freezing winter months to the spring, acting as an initial condition for subsequent summer land-surface and rainfall conditions. Both the soil moisture and vegetation memories were prominent over the eastern part of the Mongolian steppe zone (103-112°E and 46-50°N). That is, the cold-season climate with low evapotranspiration and strong soil freezing acts to prolong the decay time scale of autumn soil moisture anomalies to 8.2 months that is among the longest in the world. The vegetation also has a memory of the similar time scale, likely because the large rootstock of the perennial plants dominant in the Mongolian steppe may remain alive, retain belowground biomass anomalies during the winter, and have an impact on the initial vegetation growth during the spring.

  4. Study of land degradation and desertification dynamics in North Africa areas using remote sensing techniques

    OpenAIRE

    Afrasinei, Gabriela Mihaela

    2016-01-01

    In fragile-ecosystem arid and semi-arid land, climatic variations, water scarcity and human pressure accelerate ongoing degradation of natural resources. In order to implement sustainable management, the ecological state of the land must be known and diachronic studies to monitor and assess desertification processes are indispensable in this respect. The present study is developed in the frame of WADIS-MAR (www.wadismar.eu). This is one of the five Demonstration Projects implem...

  5. Assessment of the desertification vulnerability of the Cappadocian district (Central Anatolia, Turkey based on aridity and climate-process system

    Directory of Open Access Journals (Sweden)

    Murat Türkeş

    2011-03-01

    Full Text Available The present study discusses climate of the Cappadocian district in Turkey on the basis of Thornthwaite’s climate classification and water budget, Erinç’s aridity index and United Nations Convention to Combat Desertification (UNCCD aridity index, along with the spatial and inter-seasonal variations of precipitation and air temperatures. Vulnerability of the Cappadocia to desertification processes was also investigated with respect to the aridity, lithology dominated by tuffs and climate-process system and present land-use features of the district. The data analysis revealed that coefficients of variation (CV of the mean and maximum temperatures are the greatest in summer and the smallest in winter. Nevşehir and Kayseri environs are the most continental parts of the Cappadocia with a high inter-annual variability and low temperatures. Cappadocia is characterized with a continental rainfall regime having a maximum precipitation in spring. Variability of summer precipitation totals is greater than that of other seasons, varying from 65.7% to 78%. The CVs of the annual precipitation totals are about 18% at north and about 20% at south. Semi-arid and dry sub-humid or semi-humid climate types prevail over Cappadocia according to Thornthwaite’s moisture and Erinç’s aridity indices. Steppe is the dominant vegetation formation with sparse dry forests. The Cappadocia is vulnerable to the desertification processes due to both natural factors (e.g. degree of aridity, climate-process system, weathering of tuffs, erosion, climate change, etc. and human-involvement (e.g. land degradation and intensive tourism, etc.. In order to mitigate desertification and to preserve the historical and cultural heritages in Cappadocia, sustainable land-use management and tourism planning applications are urgently needed.

  6. Assessment of the desertification vulnerability of the Cappadocian district (Central Anatolia, Turkey based on aridity and climate-process system

    Directory of Open Access Journals (Sweden)

    Murat Türkeş

    2011-03-01

    Full Text Available The present study discusses climate of the Cappadocian district in Turkey on the basis of Thornthwaite’s climate classification and water budget, Erinç’s aridity index and United Nations Convention to Combat Desertification (UNCCD aridity index, along with the spatial and inter-seasonal variations of precipitation and air temperatures. Vulnerability of the Cappadocia to desertification processes was also investigated with respect to the aridity, lithology dominated by tuffs and climate-process system and present land-use features of the district. The data analysis revealed that coefficients of variation (CV of the mean and maximum temperatures are the greatest in summer and the smallest in winter. Nevşehir and Kayseri environs are the most continental parts of the Cappadocia with a high inter-annual variability and low temperatures. Cappadocia is characterized with a continental rainfall regime having a maximum precipitation in spring. Variability of summer precipitation totals is greater than that of other seasons, varying from 65.7% to 78%. The CVs of the annual precipitation totals are about 18% at north and about 20% at south. Semi-arid and dry sub-humid or semi-humid climate types prevail over Cappadocia according to Thornthwaite’s moisture and Erinç’s aridity indices. Steppe is the dominant vegetation formation with sparse dry trees. The Cappadocia is vulnerable to the desertification processes due to both natural factors (e.g. degree of aridity, climate-process system, weathering of tuffs, erosion, climate change, etc. and human-involvement (e.g. land degradation and intensive tourism, etc.. In order to mitigate desertification and to preserve the historical and cultural heritages in Cappadocia, sustainable land-use management and tourism planning applications are urgently needed.

  7. Global and continental changes of arid areas using the FAO Aridity Index over the periods 1951-1980 and 1981-2010

    Science.gov (United States)

    Spinoni, Jonathan; Micale, Fabio; Carrao, Hugo; Naumann, Gustavo; Barbosa, Paulo; Vogt, Jürgen

    2013-04-01

    An increase in arid areas and progressing land degradation are two of the main consequences of global climate change. In the 2nd edition of the World Atlas of Desertification (WAD), published by the United Nation Environment Program (UNEP) in 1997, a global aridity map was presented. This map was based on the Food and Agriculture Organization (FAO) Aridity Index (AI) that takes into account the annual ratio between precipitation (RR) and Potential Evapo-Transpiration (PET). According to the long-term mean value of this ratio, climate is therefore classified in hyper-arid (0.65); a special case are cold climates, which occur if the mean annual PET is below 400 mm. In the framework of the 3rd edition of the WAD, we computed new global aridity maps to improve and update the old version that was based on a single dataset (CRU dataset, Climate Research Unit of University of East Anglia) related to the 1951-80 period only. We computed the AI on two different time intervals (1951-80 and 1981-2010) in order to account for shifts in classes between the two periods and we used two different datasets: PET from CRU (version 3.2), and precipitation from the global 0.5˚x0.5˚ gridded monthly precipitation of the Global Precipitation Climatology Center (GPCC) of the Deutscher Wetterdienst (DWD). We used the GPCC Full Data Reanalysis Version 6.0, which showed a high reliability during many quality checks and is based on more stations than the CRU's precipitation counterpart. The results show that the "arid areas" (i.e. AI Spain, the Southern Sahara and North-Eastern Kalahari deserts, Rajasthan and Madhya Pradesh (India), Mongolia, the Yang-Tze Basin (China), and the North-Eastern and South-Western Australian coasts. On the other hand, Central U.S., Paraguay and Northern Argentina, Scandinavia, Northern Australia, and Western China moved to a wetter climate in the last period. Due to the low data availability, we assumed that no changes took place in Antarctica, which is meant to

  8. Scarce data in hydrology and hydrogeology: Estimation and modelling of groundwater recharge for a numerical groundwater flow model in a semi-arid to arid catchment

    Science.gov (United States)

    Gräbe, Agnes; Schulz, Stephan; Rödiger, Tino; Kolditz, Olaf

    2013-04-01

    Water resources are strongly limited in semi-arid to arid regions and groundwater constitutes often the only possibility for fresh water for the population and industry. An understanding of the hydrological processes and the estimation of magnitude of water balance parameters also includes the knowledge of processes of groundwater recharge. For the sustainable management of water resources, it is essential to estimate the potential groundwater recharge under the given climatic conditions. We would like to present the results of a hydrological model, which is based on the HRU- concept and intersected the parameters of climatic conditions, topography, geology, soil, vegetation and land use to calculate the groundwater recharge. This model was primarily developed for humid area applications and has now been adapted to the regional conditions in the semi-arid to arid region. It was quite a challenge to understand the hydrological processes in the semi-arid to arid study area and to implement those findings (e.g. routing [Schulz (in prep.)]) into the model structure. Thus we compared the existing approaches for groundwater recharge estimations (chloride mass balance [Marei et. al 2000], empirical relations such as rainfall and base flow-relation [Goldschmidt 1960; Guttman 2000; Hughes 2008; Issar 1993; Lerner 1990; De Vries et. al 2002]) with the results of our numerical model. References: De Vries, J. J., I. Simmers (2002): Groundwater recharge: an overview of processes and challenges. Hydrogeology Journal (2002) 10: 5-17. DOI 10.1007/s10040-001-0171-7. Guttman, J., 2000. Multi-Lateral Project B: Hydrogeology of the Eastern Aquifer in the Judea Hills and Jordan Valley. Mekorot Water Company, Report 468, p. 36. Hughes, A. G., M. M. Mansour, N. S. Robins (2008): Evaluation of distributed recharge in an upland semi-arid karst system: the West Bank Mountain Aquifer, Middle East. Hydrogeology Journal (2008) 16: 845-854. DOI 10.1007/s10040-008-0273-6 Issar, A. S. (1993

  9. The ecohydrology of the soil-vegetation system restoration in arid zones: a review

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Arid zones, which cover approximately 40 percent of the earth’s land surface, support complicated and widely varied ecological systems. As such, arid zones are an important composition of the global terrestrial ecosystem, and water is the key and abiotic lim-ited factor in ecosystem-driven processes in these areas. Ecohydrology is a new cross discipline that provides, in an objective and comprehensive manner, novel ideas and approaches to the evaluation of the interaction and feedback mechanisms involved in the soil-vegetation systems in arid zones. In addition, ecohydrology provides a theoretical basis of ecological restoration that is cen-tered on vegetation construction. In this paper, long-term monitoring and local observations in the transitional belt between a de-sertified steppe and a steppified desert at the Shapotou Desert Research and Experiment Station, Tengger Desert, in northern China, were evaluated. The primary achievements and related research progress regarding ecohydrology in arid zones were analyzed and summarized, as a keystone, and the response of soil ecohydrological processes to the changes in the species composition, structure, and function of sandland vegetation was discussed. Meanwhile, the long-term ecological effects and mechanism of regulation of vegetation on soil habitat and on water-cycling were considered. As a vital participant in the ecohydrological processes of soil-vegetation systems, the studies on biological soil crusts was also summarized, and related theoretical models of restoration based on the water balance was reviewed.

  10. An effect of spatial resolution of remotely sensed data for vegetation analysis over an arid zone

    Science.gov (United States)

    Oguro, Y.; Tsuchiya, K.; Setoguchi, R.

    1997-05-01

    One of the recent trends in the development of an optical sensor of earth observation satellite is a great importance of spatial resolution and the order of 1 - 2 meter resolution sensor is under development. To cope with this trend analyses are made on the effect of extremely fine spatial resolution of land cover classification accuracy utilizing spatial resolution of 20 cm and 1 meter aerial multi-sensor data of an arid reddish land where desertification is taking place in small spatial scale. Applied methods are supervised classification with combination of multi-level slice(pallarelpiped classification) and the Mahalanobis distance. The result of analysis indicates that the difference is within several percentage for 3 categories of bare land, vegetation and shadow. It was also found that small dried sparse grass land which can be recognized in 20 cm resolution image is difficult to extract in 1 meter resolution image.

  11. Enclosing the commons: reasons for the adoption and adaptation of enclosures in the arid and semi-arid rangelands of Chepareria, Kenya.

    Science.gov (United States)

    Wairore, John N; Mureithi, Stephen M; Wasonga, Oliver V; Nyberg, Gert

    2015-01-01

    The adoption and adaptation of enclosures in the arid and semi-arid rangelands of sub-Saharan Africa is driven and sustained by a combination of factors. However, reviews indicate that these factors cannot be generalized, as they tend to be case specific. A study was therefore conducted to explore the history and reasons for enclosure establishment in Chepareria, a formerly degraded communal rangeland in north-western Kenya. While Vi-Agroforestry Organization accounting for 52.5 % was the main source of knowledge on enclosure establishment; it has now emerged that rangeland enclosures among the Pokot pastoral community existed prior to land management interventions by Vi- Agroforestry. Results indicated that there are three categories of enclosures which were established for boundary demarcation, provide grazing reserves, enable proper land management, facilitate crop cultivation in a pastoral setup and to curb land degradation. The role of self-trigger [accounting for most of the spontaneous enclosures (73.5 %)] indicates the continued establishment and expansion of areas under enclosure management as private land ownership accounting for 51.7 % of enclosure tenure continues to gain momentum in Chepareria. While rangeland enclosures in Chepareria were mainly established for boundary demarcation, to alleviate pasture scarcity and enable proper management of formerly degraded areas; they have facilitated land restoration and rehabilitation by increasing flexibility in land, fodder and livestock management amongst agro-pastoralists in Chepareria over the last three decades. To ensure that rehabilitated areas do not revert to their previously degraded state; technical interventions are needed to allow for a more intensive use of rangeland resources within enclosed areas.

  12. Land use in the karstic lands in the Mediterranean region.

    Directory of Open Access Journals (Sweden)

    Atalay Ibrahim

    1999-01-01

    Full Text Available Karstic lands have special importance in terms of soil formation and land-use. Soil appears only on the flat and slightly undulating karstic lands, while soils are found along the cracks and bedding surfaces between the layers on the hilly karst areas although these lands are rocky in appearance. Karstic lands in the hilly area are not conducive to cultivation. But rocky areas create a favourable habitat for the growth of forests except in an arid climate. Because the tree roots easily follow and develop along the cracks in the limestone. As a general rule soil erosion does not occur on sub-horizontal karst surfaces due to the fact that atmospheric waters easily infiltrate along the cracks. Natural generation of vegetation like the maquis-type occurs via the root suckers, but coniferous trees such as cedar, fir, pine through seed dispersal. The clearance of natural vegetation on the karstic lands leads to the formation of bare lands. That is why the slopes of the limestone hillsides have been converted into bare and/or rocky terrains in places where natural vegetation has been completely destroyed.

  13. Sources and transport of nitrogen in arid urban watersheds.

    Science.gov (United States)

    Hale, Rebecca L; Turnbull, Laura; Earl, Stevan; Grimm, Nancy; Riha, Krystin; Michalski, Greg; Lohse, Kathleen A; Childers, Daniel

    2014-06-03

    Urban watersheds are often sources of nitrogen (N) to downstream systems, contributing to poor water quality. However, it is unknown which components (e.g., land cover and stormwater infrastructure type) of urban watersheds contribute to N export and which may be sites of retention. In this study we investigated which watershed characteristics control N sourcing, biogeochemical processing of nitrate (NO3-) during storms, and the amount of rainfall N that is retained within urban watersheds. We used triple isotopes of NO3- (δ15N, δ18O, and Δ17O) to identify sources and transformations of NO3- during storms from 10 nested arid urban watersheds that varied in stormwater infrastructure type and drainage area. Stormwater infrastructure and land cover--retention basins, pipes, and grass cover--dictated the sourcing of NO3- in runoff. Urban watersheds were strong sinks or sources of N to stormwater depending on runoff, which in turn was inversely related to retention basin density and positively related to imperviousness and precipitation. Our results suggest that watershed characteristics control the sources and transport of inorganic N in urban stormwater but that retention of inorganic N at the time scale of individual runoff events is controlled by hydrologic, rather than biogeochemical, mechanisms.

  14. Sources and transport of nitrogen in arid urban watersheds

    Energy Technology Data Exchange (ETDEWEB)

    Hale, Rebecca L.; Turnbull, Laura; Earl, Stevan; Grimm, Nancy B.; Riha, Krystin M.; Michalski, Greg; Lohse, Kathleen; Childers, Daniel L.

    2014-06-03

    Urban watersheds are often sources of nitrogen (N) to downstream systems, contributing to poor water quality. However, it is unknown which components (e.g., land cover and stormwater infrastructure type) of urban watersheds contribute to N export and which may be sites of retention. In this study we investigated which watershed characteristics control N sourcing, biogeochemical processing of nitrate (NO3–) during storms, and the amount of rainfall N that is retained within urban watersheds. We used triple isotopes of NO3– (δ15N, δ18O, and Δ17O) to identify sources and transformations of NO3– during storms from 10 nested arid urban watersheds that varied in stormwater infrastructure type and drainage area. Stormwater infrastructure and land cover—retention basins, pipes, and grass cover—dictated the sourcing of NO3– in runoff. Urban watersheds can be strong sinks or sources of N to stormwater depending on the proportion of rainfall that leaves the watershed as runoff, but we found no evidence that denitrification occurred during storms. Our results suggest that watershed characteristics control the sources and transport of inorganic N in urban stormwater but that retention of inorganic N at the timescale of individual runoff events is controlled by hydrologic, rather than biogeochemical, mechanisms.

  15. Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

    OpenAIRE

    Emmanuel Mavhura; Desmond Manatsa; Terence Mushore

    2015-01-01

    Small-scale rain-fed agriculture is the main livelihood in arid to semi-arid regions of subSaharan Africa. The area is characterised by erratic rainfall and frequent droughts, making the capacity for coping with temporal water shortages essential for smallholder farmers. Focusing on the Zambezi Valley, Zimbabwe, this study investigates the impact of drought on food security and the strategies used by smallholder farmers to cope with drought. We used meteorological data and interviews to exami...

  16. Analyzing Landscape Trends on Agriculture, Introduced Exotic Grasslands and Riparian Ecosystems in Arid Regions of Mexico

    Directory of Open Access Journals (Sweden)

    Romeo Mendez-Estrella

    2016-08-01

    Full Text Available Riparian Zones are considered biodiversity and ecosystem services hotspots. In arid environments, these ecosystems represent key habitats, since water availability makes them unique in terms of fauna, flora and ecological processes. Simple yet powerful remote sensing techniques were used to assess how spatial and temporal land cover dynamics, and water depth reflect distribution of key land cover types in riparian areas. Our study area includes the San Miguel and Zanjon rivers in Northwest Mexico. We used a supervised classification and regression tree (CART algorithm to produce thematic classifications (with accuracies higher than 78% for 1993, 2002 and 2011 using Landsat TM scenes. Our results suggest a decline in agriculture (32.5% area decrease and cultivated grasslands (21.1% area decrease from 1993 to 2011 in the study area. We found constant fluctuation between adjacent land cover classes and riparian habitat. We also found that water depth restricts Riparian Vegetation distribution but not agricultural lands or induced grasslands. Using remote sensing combined with spatial analysis, we were able to reach a better understanding of how riparian habitats are being modified in arid environments and how they have changed through time.

  17. Aridity and decomposition processes in complex landscapes

    Science.gov (United States)

    Ossola, Alessandro; Nyman, Petter

    2015-04-01

    Decomposition of organic matter is a key biogeochemical process contributing to nutrient cycles, carbon fluxes and soil development. The activity of decomposers depends on microclimate, with temperature and rainfall being major drivers. In complex terrain the fine-scale variation in microclimate (and hence water availability) as a result of slope orientation is caused by differences in incoming radiation and surface temperature. Aridity, measured as the long-term balance between net radiation and rainfall, is a metric that can be used to represent variations in water availability within the landscape. Since aridity metrics can be obtained at fine spatial scales, they could theoretically be used to investigate how decomposition processes vary across complex landscapes. In this study, four research sites were selected in tall open sclerophyll forest along a aridity gradient (Budyko dryness index ranging from 1.56 -2.22) where microclimate, litter moisture and soil moisture were monitored continuously for one year. Litter bags were packed to estimate decomposition rates (k) using leaves of a tree species not present in the study area (Eucalyptus globulus) in order to avoid home-field advantage effects. Litter mass loss was measured to assess the activity of macro-decomposers (6mm litter bag mesh size), meso-decomposers (1 mm mesh), microbes above-ground (0.2 mm mesh) and microbes below-ground (2 cm depth, 0.2 mm mesh). Four replicates for each set of bags were installed at each site and bags were collected at 1, 2, 4, 7 and 12 months since installation. We first tested whether differences in microclimate due to slope orientation have significant effects on decomposition processes. Then the dryness index was related to decomposition rates to evaluate if small-scale variation in decomposition can be predicted using readily available information on rainfall and radiation. Decomposition rates (k), calculated fitting single pool negative exponential models, generally

  18. Impact of soil salinity on arbuscular mycorrhizal fungi biodiversity and microflora biomass associated with Tamarix articulata Vahll rhizosphere in arid and semi-arid Algerian areas.

    Science.gov (United States)

    Bencherif, Karima; Boutekrabt, Ammar; Fontaine, Joël; Laruelle, Fréderic; Dalpè, Yolande; Sahraoui, Anissa Lounès-Hadj

    2015-11-15

    Soil salinization is an increasingly important problem in many parts of the world, particularly under arid and semi-arid areas. Unfortunately, the knowledge about restoration of salt affected ecosystems using mycorrhizae is limited. The current study aims to investigate the impact of salinity on the microbial richness of the halophytic plant Tamarix articulata rhizosphere. Soil samples were collected from natural sites with increasing salinity (1.82-4.95 ds.m(-1)). Six arbuscular mycorrhizal fungi (AMF) species were isolated from the different saline soils and identified as Septoglomus constrictum, Funneliformis mosseae, Funneliformis geosporum, Funneliformis coronatum, Rhizophagus fasciculatus, and Gigaspora gigantea. The number of AMF spores increased with soil salinity. Total root colonization rate decreased from 65 to 16% but remained possible with soil salinity. Microbial biomass in T. articulata rhizosphere was affected by salinity. The phospholipid fatty acids (PLFA) C16:1ω5 as well as i15:0, a15:0, i16:0, i17:0, a17:0, cy17:0, C18:1ω7 and cy19:0 increased in high saline soils suggesting that AMF and bacterial biomasses increased with salinity. In contrast, ergosterol amount was negatively correlated with soil salinity indicating that ectomycorrhizal and saprotrophic fungal biomasses were reduced with salinity. Our findings highlight the adaptation of arbuscular and bacterial communities to natural soil salinity and thus the potential use of mycorrhizal T. articulata trees as an approach to restore moderately saline disturbed arid lands.

  19. Analysis list: Arid1a [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Arid1a Adipocyte + mm9 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Arid1a....1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Arid1a.5.tsv http://dbarchive.biosciencedbc.jp/...kyushu-u/mm9/target/Arid1a.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Arid1a.Adipocyte.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Adipocyte.gml ...

  20. Improvement of Surface Albedo Simulations over Arid Regions

    Institute of Scientific and Technical Information of China (English)

    BAO Yan; L(U) Shihua; ZHANG Yu; MENG Xianhong; YANG Shengpeng

    2008-01-01

    To improve the simulation of the surface radiation budget and related thermal processes in arid regions, three sophisticated surface albedo schemes designed for such regions were incorporated into the Biosphere-Atmosphere Transfer Scheme (BATS). Two of these schemes are functions of the solar zenith angle (SZA), where the first one has one adjustable parameter defined as SZA1 scheme, and the second one has two empir-ical parameters defined as SZA2 scheme. The third albedo scheme is a function of solar angle and soil water that were developed based on arid-region observations from the Dunhuang field experiment (DHEX) (defined as DH scheme). We evaluated the performance of the original and newly-incorporated albedo schemes within BATS using the in-situ data from the Oasis System Energy and Water Cycle Field Experiment that was carried out in JinTa, Gansu arid area (JTEX). The results indicate that a control run by the original version of the BATS generates a constant albedo, while the SZA1 and SZA2 schemes basically can reproduce the observed diurnal cycle of surface albedo, although these two schemes still underestimate the albedo when SZA is high in the early morning and late afternoon, and overestimate it when SZA is low during noontime. The SZA2 scheme has a better overall performance than the SZA1 scheme. In addition, BATS with the DH scheme slightly improves the albedo simulation in magnitude as compared to that from the control run, but a diurnal cycle of albedo is not produced by this scheme. The SZAl and SZA2 schemes significantly increase the surface absorbed solar radiation by nearly 70 W m~2, which further raises the ground temperature by 6 K and the sensible heat flux by 35 W m~2. The increased solar radiation, heat flux, and temperature are more consistent with the observations that those from the control run. However, a significant improvement in these three variables is not found in BATS with the DH scheme due to the neglect of the diurnal cycle of

  1. Satellite-Based Monitoring of Decadal Soil Salinization and Climate Effects in a Semi-arid Region of China

    Institute of Scientific and Technical Information of China (English)

    WANG Hesong; JIA Gensuo

    2012-01-01

    Soil salinization is a common phenomenon that affects both the environment and the socio-economy in arid and semi-arid regions; it is also an important aspect of land cover change.In this study,we integrated multi-sensor remote sensing data with a field survey to analyze processes of soil salinization in a semi-arid area in China from 1979 to 2009. Generally,the area of salt-affected soils increased by 0.28% per year with remarkable acceleration from 1999 to 2009 (0.42% increase per year).In contrast,the area of surface water bodies showed a decreasing trend (-0.08% per year) in the same period.Decreases in precipitation and increases in aridity due to annual (especially summer) warming provided a favorable condition for soil salinization. The relatively flat terrain favored waterlogging at the surface,and continuous drought facilitated upward movement of soil water and accumulation of surface saline and calcium. Meanwhile,land-use practices also played a crucial role in accelerating soil salinization.The conversion to cropland from natural vegetation greatly increased the demand for groundwater irrigation and aggravated the process of soil salinization.Furthermore,there are potential feedbacks of soil salinization to regional climate.The salinization of soils can limit the efficiency of plant water use as well as photosynthesis; therefore,it reduces the amount of carbon sequestrated by terrestrial ecosystem.Soil salinization also reduces the absorbed solar radiation by increasing land surface albedo.Such conversions of land cover significantly change the energy and water balance between land and atmosphere.

  2. Bulk transfer coefficients of the atmospheric momentum and sensible heat over desert and Gobi in arid climate region of Northwest China

    Institute of Scientific and Technical Information of China (English)

    张强; 卫国安; 黄荣辉; 曹晓彦

    2002-01-01

    By utilizing the data of the intensive observation period (May-June, 2000) of Dunhuang land-surface process field experiment that belongs to "Land-atmosphere Interactive Field Experiment over Arid Region of Northwest China", the bulk momentum transfer coefficient Cd and bulk sensible heat transfer coefficient Ch between surface and atmosphere over desert and Gobi in the arid region are determined according to three different methods. The result shows that, though these bulk transfer coefficients are different, they are in the same order. Especially, the means of Cd and Ch are close. Moreover, through analyzing the wind direction, the interference of the building near the observational station with the data is eliminated. From this, the relation between the bulk transfer coefficients and the bulk Richardson number and the range of the typical values of the bulk transfer coefficients over desert and Gobi in the typical arid region are obtained.

  3. Rainfall Characterization In An Arid Area

    OpenAIRE

    Bazaraa, A. S.; Ahmed, Shamim

    1991-01-01

    The objective of this work is to characterize the rainfall in Doha which lies in an arid region. The rainfall data included daily rainfall depth since 1962 and the hyetographs of the individual storms since 1976. The rainfall is characterized by high variability and severe thunderstorms which are of limited geographical extent. Four probability distributions were used to fit the maximum rainfall in 24 hours and the annual rainfall depth. The extreme value distribution was found to have the be...

  4. VOCs in Arid soils: Technology summary

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    The Volatile Organic Compounds In Arid Soils Integrated Demonstration (VOC-Arid ID) focuses on technologies to clean up volatile organic compounds and associated contaminants in soil and groundwater at arid sites. The initial host site is the 200 West Area at DOE`s Hanford site in southeastern Washington state. The primary VOC contaminant is carbon tetrachloride, in association with heavy metals and radionuclides. An estimated 580--920 metric tons of carbon tetrachloride were disposed of between 1955 and 1973, resulting in extensive soil and groundwater contamination. The VOC-Arid ID schedule has been divided into three phases of implementation. The phased approach provides for: rapid transfer of technologies to the Environmental Restoration (EM-40) programs once demonstrated; logical progression in the complexity of demonstrations based on improved understanding of the VOC problem; and leveraging of the host site EM-40 activities to reduce the overall cost of the demonstrations. During FY92 and FY93, the primary technology demonstrations within the ID were leveraged with an ongoing expedited response action at the Hanford 200 West Area, which is directed at vapor extraction of VOCs from the vadose (unsaturated) zone. Demonstration efforts are underway in the areas of subsurface characterization including: drilling and access improvements, off-gas and borehole monitoring of vadose zone VOC concentrations to aid in soil vapor extraction performance evaluation, and treatment of VOC-contaminated off-gas. These current demonstration efforts constitute Phase 1 of the ID and, because of the ongoing vadose zone ERA, can result in immediate transfer of successful technologies to EM-40.

  5. Aridity increases below-ground niche breadth in grass communities

    Science.gov (United States)

    Butterfield, Bradley J.; Bradford, John B.; Munson, Seth M.; Gremer, Jennifer R.

    2017-01-01

    Aridity is an important environmental filter in the assembly of plant communities worldwide. The extent to which root traits mediate responses to aridity, and how they are coordinated with leaf traits, remains unclear. Here, we measured variation in root tissue density (RTD), specific root length (SRL), specific leaf area (SLA), and seed size within and among thirty perennial grass communities distributed along an aridity gradient spanning 190–540 mm of climatic water deficit (potential minus actual evapotranspiration). We tested the hypotheses that traits exhibited coordinated variation (1) among species, as well as (2) among communities varying in aridity, and (3) functional diversity within communities declines with increasing aridity, consistent with the “stress-dominance” hypothesis. Across communities, SLA and RTD exhibited a coordinated response to aridity, shifting toward more conservative (lower SLA, higher RTD) functional strategies with increasing aridity. The response of SRL to aridity was more idiosyncratic and was independent of variation in SLA and RTD. Contrary to the stress-dominance hypothesis, the diversity of SRL values within communities increased with aridity, while none of the other traits exhibited significant diversity responses. These results are consistent with other studies that have found SRL to be independent of an SLA–RTD axis of functional variation and suggest that the dynamic nature of soil moisture in arid environments may facilitate a wider array of resource capture strategies associated with variation in SRL.

  6. Semi-Arid Water Resource Challenges - Can Water Harvesting Close the Gap?

    Science.gov (United States)

    Meixner, T.; Niraula, R.; Norman, L.; Pivo, G.; Gerlak, A.; Pavao-Zuckerman, M.; Henry, A.

    2015-12-01

    Water resource availability restricts development in arid and semi-arid regions of world. Past observations show that urban areas can increase stream discharge at least on a local scale. These results suggest that urbanization may increase the availability of wet water capable of being used by urban society. Here we present a combination of observational work demonstrating the increase of available water in urban areas of southern Arizona; and a modelling study demonstrating that future land use change may significantly increase river discharge across the Santa Cruz watershed which is ~12% urban. The observational data comes from over 30 watersheds varying in cover from undeveloped to highly urban and in spatial scale from a few square meters to thousands of square kilometers. The modelling study includes a conservation (~35% urban), megalopolitan (~34% urban) and business as usual scenario (~38% urban) for land use change due to regional population growth. All land use change scenarios result in significant increases in watershed streamflow. Depending upon pattern of urbanization, streamflow increased as much 88% in some watershed locations; demonstrating the potential to partially meet water resources demands in the region with water produced by the urbanization process. This water could be used regionally or locally, and significant efforts at implementing water harvesting in the region have been pursued. However, the ability to scale such implementation and overcome the physical, and social barriers to implementation are currently unquantified.

  7. Diurnal and Seasonal Variation of Surface Urban Cool and Heat Islands in the Semi-Arid City of Erbil, Iraq

    OpenAIRE

    Azad Rasul; Heiko Balzter; Claire Smith

    2016-01-01

    The influence of land surface temperature (LST) makes the near-surface layer of the troposphere a key driver of urban climate. This paper assesses the temporal formation of the daytime Surface Urban Cool Island (SUCI) and night-time Surface Urban Heat Island (SUHI) effect in Erbil, Iraq, situated in a semi-arid climate region. LST retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra and MODIS Normalized Difference Vegetation Index (NDVI) from January 2003 t...

  8. Parameterization of almanac crop simulation model for non-irrigated dry bean in semi-arid temperate areas in Mexico

    OpenAIRE

    Alma Delia Baez-Gonzalez; James R. Kiniry; Jose Saul Padilla Ramirez; Guillermo Medina Garcia; Jose Luis Ramos Gonzalez; Esteban Salvador Osuna Ceja

    2015-01-01

    Dry bean simulation models can be used to make management decisions when properly parameterized. This study aimed to parameterize the ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) crop simulation model for dry bean in the semi-arid temperate areas of Mexico. The parameterization process was based on data from two important non-irrigated dry bean fields in Mexico. The parameters were potential heat units (PHU), leaf area index (LAI) and harvest index (H...

  9. Diagnosis of GLDAS LSM based aridity index and dryland identification for socioeconomic aspect of water resources management

    Science.gov (United States)

    Ghazanfari, S.; Pande, S.; Hashemy, M.; Naseri M., M.

    2012-04-01

    Water resources scarcity plays an important role in socioeconomic aspect of livelihood pattern in dryland areas. Hydrological perspective of aridity is required for social and economic coping Strategies. Identification of dryland areas is crucial to guide policy aimed at intervening in water stressed areas and addressing its perennial livelihood or food insecurity. Yet, prevailing aridity indices are beset with methodological limitations that restrict their use in delineating drylands and, might be insuffient for decision making frameworks. Palmer's Drought Severity index (PDSI) reports relative soil moisture deviations from long term means, which does not allow cross comparisons, while UNEP's aridity index, the ratio of annual evaporative demand to rainfall supply, ignores site specific soil and vegetation characteristics that are needed for appropriate water balance assessment. We propose to refine UNEP's aridity index by accounting for site specific soil and vegetation to partition precipitation into competing demands of evaporation and runoff. We create three aridity indices at a 1 x 1 degree spatial resolution based on 3 decades of soil moisture time series from three GLDAS Land Surface Models (LSM's): VIC, MOSAIC and NOAH. We compare each LSM model aridity map with the UNEP aridity map which was created based on LSM data forcing. Our approach is to extract the first Eigen function from Empirical Orthogonal Function (EOF) analysis that represents the dominant spatial template of soil moisture conditions of the three LSM's. Frequency of non-exceedence of this dominant soil moisture mode for a location by all other locations is used as our proposed aridity index. The EOF analysis reveals that the first Eigen function explains, respectively, 33%, 43% and 47% of the VIC, NOAH and MOSAIC models. The temporal coefficients associated with the first OF (Orthogonal Function) for all three LSMS clearly show seasonality with a discrete jump in trend around the year 1999

  10. Land acquisition

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a summary of lands acquired by Neal Smith National Wildlife Refuge between 1991 and 2009. Lists of acres and locations of land acquired are provided for...

  11. Land Cover

    Data.gov (United States)

    Kansas Data Access and Support Center — The Land Cover database depicts 10 general land cover classes for the State of Kansas. The database was compiled from a digital classification of Landsat Thematic...

  12. Arid sites stakeholder participation in evaluating innovative technologies: VOC-Arid Site Integrated Demonstration

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, T.S.; McCabe, G.H.; Brockbank, B.R. [and others

    1995-05-01

    Developing and deploying innovative environmental cleanup technologies is an important goal for the U.S. Department of Energy (DOE), which faces challenging remediation problems at contaminated sites throughout the United States. Achieving meaningful, constructive stakeholder involvement in cleanup programs, with the aim of ultimate acceptance of remediation decisions, is critical to meeting those challenges. DOE`s Office of Technology Development sponsors research and demonstration of new technologies, including, in the past, the Volatile Organic Compounds Arid Site Integrated Demonstration (VOC-Arid ID), hosted at the Hanford Site in Washington State. The purpose of the VOC-Arid ID has been to develop and demonstrate new technologies for remediating carbon tetrachloride and other VOC contamination in soils and ground water. In October 1994 the VOC-Arid ID became a part of the Contaminant Plume Containment and Remediation Focus Area (Plume Focus Area). The VOC Arid ID`s purpose of involving stakeholders in evaluating innovative technologies will now be carried on in the Plume Focus Area in cooperation with Site Technology Coordination Groups and Site Specific Advisory Boards. DOE`s goal is to demonstrate promising technologies once and deploy those that are successful across the DOE complex. Achieving that goal requires that the technologies be acceptable to the groups and individuals with a stake in DOE facility cleanup. Such stakeholders include groups and individuals with an interest in cleanup, including regulatory agencies, Native American tribes, environmental and civic interest groups, public officials, environmental technology users, and private citizens. This report documents the results of the stakeholder involvement program, which is an integral part of the VOC-Arid ID.

  13. Analysis list: ARID3A [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ARID3A Blood,Liver + hg19 http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ARID3A.1.tsv http:...//dbarchive.biosciencedbc.jp/kyushu-u/hg19/target/ARID3A.5.tsv http://dbarchive.biosciencedb...c.jp/kyushu-u/hg19/target/ARID3A.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ARID3A.Blood.tsv,http:...//dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/ARID3A.Liver.tsv http://db...archive.biosciencedbc.jp/kyushu-u/hg19/colo/Blood.gml,http://dbarchive.biosciencedbc.jp/kyushu-u/hg19/colo/Liver.gml ...

  14. Functional diversity enhances the resistance of ecosystem multifunctionality to aridity in Mediterranean drylands.

    Science.gov (United States)

    Valencia, Enrique; Maestre, Fernando T; Le Bagousse-Pinguet, Yoann; Quero, José Luis; Tamme, Riin; Börger, Luca; García-Gómez, Miguel; Gross, Nicolas

    2015-04-01

    We used a functional trait-based approach to assess the impacts of aridity and shrub encroachment on the functional structure of Mediterranean dryland communities (functional diversity (FD) and community-weighted mean trait values (CWM)), and to evaluate how these functional attributes ultimately affect multifunctionality (i.e. the provision of several ecosystem functions simultaneously). Shrub encroachment (the increase in the abundance/cover of shrubs) is a major land cover change that is taking place in grasslands worldwide. Studies conducted on drylands have reported positive or negative impacts of shrub encroachment depending on the functions and the traits of the sprouting or nonsprouting shrub species considered. FD and CWM were equally important as drivers of multifunctionality responses to both aridity and shrub encroachment. Size traits (e.g. vegetative height or lateral spread) and leaf traits (e.g. specific leaf area and leaf dry matter content) captured the effect of shrub encroachment on multifunctionality with a relative high accuracy (r(2)  = 0.63). FD also improved the resistance of multifunctionality along the aridity gradient studied. Maintaining and enhancing FD in plant communities may help to buffer negative effects of ongoing global environmental change on dryland multifunctionality.

  15. Analysis list: Arid3a [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Arid3a Pluripotent stem cell + mm9 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Ari...d3a.1.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/target/Arid3a.5.tsv http://dbarchive.biosc...iencedbc.jp/kyushu-u/mm9/target/Arid3a.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Arid3a.Pluri...potent_stem_cell.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Pluripotent_stem_cell.gml ...

  16. Mining the Agave Microbiome for adaptions to arid environments

    Energy Technology Data Exchange (ETDEWEB)

    Coleman-Derr, Devin; Wojke, Tanja; North, Gretchen; Partida-Martinez, Laila; DeAngeli, Kristen; Clingenpeel, Scott; Gross, Stephen; Tringe, Susannah; Visel, Axel

    2013-03-25

    A major challenge facing the biofuels industry is the identification of high-yield plant feedstocks that can be cultivated with minimal resource inputs without competing for land and water supplies with existing food crops. Recent research has demonstrated that the Agave plant, cultivated in Mexico and Southwestern United States for the production of fiber and alcohol, meets these criteria1. Agaves grow on non-arable rocky soils in regions characterized by prolonged drought and extreme temperatures, due in part to physiological adaptions that prevent excess water-loss in arid environments2. Plant-microbial symbioses can play a role in helping plants adapt to heat and drought stress, increasing the accessibility of soil nutrients, or compete with plant pathogens3. Whether agaves have similar beneficial microbe interactions in their native environment is unknown. We aim to provide a comprehensive characterization of the Agave microbiome, with the goal of identifying specific community members that may contribute to Agave biotic and abiotic stress tolerance

  17. Water harvesting techniques for small communities in arid areas.

    Science.gov (United States)

    Yuen, E; Anda, M; Mathew, K; Ho, G

    2001-01-01

    Limited water resources exist in numerous remote indigenous settlements around Australia. Indigenous people in these communities are still living in rudimentary conditions while their urban counterparts have full amenities, large scale water supplies and behavioral practices which may not be appropriate for an arid continent but are supported by extensive infrastructure in higher rainfall coastal areas. As remote indigenous communities continue to develop, their water use will increase, and in some cases, costly solutions may have to be implemented to augment supplies. Water harvesting techniques have been applied in settlements on a small scale for domestic and municipal purposes, and in the large, broadacre farm setting for productive use of the water. The techniques discussed include swales, infiltration basins, infiltration trenches and "sand dam" basins. This paper reviews the applications of water harvesting relevant to small communities for land rehabilitation, landscaping and flood control. Landscaping is important in these communities as it provides shelter from the sun and wind, reduces soil erosion and hence reduced airborne dust, and in some cases provides food and nutrition. Case studies of water harvesting systems applied in the Pilbara Region, Western Australia for landscaping around single dwellings in Jigalong and Cheeditha, in a permaculture garden in Wittenoon and at a college and carpark in Karratha are described.

  18. Comparison modeling for alpine vegetation distribution in an arid area.

    Science.gov (United States)

    Zhou, Jihua; Lai, Liming; Guan, Tianyu; Cai, Wetao; Gao, Nannan; Zhang, Xiaolong; Yang, Dawen; Cong, Zhentao; Zheng, Yuanrun

    2016-07-01

    Mapping and modeling vegetation distribution are fundamental topics in vegetation ecology. With the rise of powerful new statistical techniques and GIS tools, the development of predictive vegetation distribution models has increased rapidly. However, modeling alpine vegetation with high accuracy in arid areas is still a challenge because of the complexity and heterogeneity of the environment. Here, we used a set of 70 variables from ASTER GDEM, WorldClim, and Landsat-8 OLI (land surface albedo and spectral vegetation indices) data with decision tree (DT), maximum likelihood classification (MLC), and random forest (RF) models to discriminate the eight vegetation groups and 19 vegetation formations in the upper reaches of the Heihe River Basin in the Qilian Mountains, northwest China. The combination of variables clearly discriminated vegetation groups but failed to discriminate vegetation formations. Different variable combinations performed differently in each type of model, but the most consistently important parameter in alpine vegetation modeling was elevation. The best RF model was more accurate for vegetation modeling compared with the DT and MLC models for this alpine region, with an overall accuracy of 75 % and a kappa coefficient of 0.64 verified against field point data and an overall accuracy of 65 % and a kappa of 0.52 verified against vegetation map data. The accuracy of regional vegetation modeling differed depending on the variable combinations and models, resulting in different classifications for specific vegetation groups.

  19. Adaptive wetland management in an uncertain and changing arid environment

    Directory of Open Access Journals (Sweden)

    Rebekah Downard

    2014-06-01

    Full Text Available Wetlands in the arid western United States provide rare and critical migratory bird habitat and constitute a critical nexus within larger social-ecological systems (SES where multiple changing land-use and water-use patterns meet. The Bear River Migratory Bird Refuge in Utah, USA, presents a case study of the ways that wetland managers have created adaptive management strategies that are responsive to the social and hydrological conditions of the agriculture-dominated SES within which they are located. Managers have acquired water rights and constructed infrastructure while cultivating collaborative relationships with other water users to increase the adaptive capacity of the region and decrease conflict. Historically, water management involved diversion and impoundment of water within wetland units timed around patterns of agricultural water needs. In the last 20 years, managers have learned from flood and drought events and developed a long-term adaptive management plan that specifies alternative management actions managers can choose each year based on habitat needs and projected water supply. Each alternative includes habitat goals and target wetland water depth. However, wetland management adapted to agricultural return-flow availability may prove insufficient as population growth and climate change alter patterns of land and water use. Future management will likely depend more on negotiation, collaboration, and learning from social developments within the SES than strictly focusing on water management within refuge boundaries. To face this problem, managers have worked to be included in negotiations with regional water users, a strategy that may prove instructive for other wetland managers in agriculture-dominated watersheds.

  20. Gambia Land Use Land Cover

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This series of three-period land use land cover (LULC) datasets (1975, 2000, and 2013) aids in monitoring change in West Africa’s land resources (exception is...

  1. Earth observing data and methods for advancing water harvesting technologies in the semi-arid rain-fed environments of India

    Science.gov (United States)

    Sharma, C.; Thenkabail, P.; Sharma, R. R.

    2011-01-01

    The paper develops approaches and methods of modeling and mapping land and water productivity of rain-fed crops in semi-arid environments of India using hyperspectral, hyperspatial, and advanced multispectral remote sensing data and linking the same to field-plot data and climate station data. The overarching goal is to provide information to advance water harvesting technologies in the agricultural croplands of the semi-arid environments of India by conducting research in a representative pilot site in Jodhpur, Rajasthan, India. ?? 2011 IEEE.

  2. Combating erosion as the main effective factor in land degradation in arid and semi-arid regions of Iran

    Energy Technology Data Exchange (ETDEWEB)

    Feiznia, S.; Kouhpelma, A.; Ahmadi, H.; Hashemi, S. A.

    2009-07-01

    Soil erosion is one of the most important environmental problems in the world including Iran. For decreasing the impacts of soil erosion, soil conservation measures are required. For successful soil conservation measures, obtaining information about the relative importance of sediment source and their shares in sediment production is required. There are different methods for determining the relative importance of sediment sources, among which tracing or source studies are emphasized in recent years due to their privileges. In this research sediment sources. (Author) 12 refs.

  3. Evaluation of MODIS LST Products Using Longwave Radiation Ground Measurements in the Northern Arid Region of China

    Directory of Open Access Journals (Sweden)

    Wenping Yu

    2014-11-01

    Full Text Available This study presents preliminary results of the validation of the Moderate Resolution Imaging Spectroradiometer (MODIS daily LST products (MOD/MYD11A1, Version 5 using longwave radiation ground measurements obtained at 12 stations in the North Arid and Semi-Arid Area Cooperative Experimental Observation Integrated Research program. In this evaluation process, the broadband emissivity at each station was obtained from the ASTER Spectral Library or estimated from the MODIS narrowband emissivity Collection 5. A comparison of the validation results based on those two methods shows that no significant differences occur in the short-term validation, and a sensitivity analysis of the broadband emissivity demonstrates that it has a limited effect on the evaluation results. In general, the results at the 12 stations indicate that the LST products have a lower accuracy in China’s arid and semi-arid areas than in other areas, with a mean absolute error of 2–3 K. Compared with the temporal mismatch, the spatial mismatch has a stronger effect on the validation results in this study, and the stations with homogeneous land cover have more comparable MODIS LST accuracies. Comparisons between the stations indicate that the spatial mismatch can increase the influence of the temporal mismatch.

  4. Implications of a New Global Picture of Land Degradation (Invited)

    Science.gov (United States)

    Olsson, L.; Dent, D.

    2009-12-01

    Effective responses to desertification have always been hampered by a lack of a scientific understanding and reliable data on the extent and severity of land degradation. We also argue that the poor scientific understanding of desertification is partly a consequence of the lack of reliable data. Policy development has to a large extent relied upon data from the 1990 GLASOD assessment that was compiled from expert judgements. This is a map of perceptions, not measurements, that doesn't stand scrutiny and lent itself to selective interpretations. Based on the GLASOD assessment, land degradation in arid and semi-arid regions have been emphasised over other regions as hotspots of land degradation. A recent analysis of consistent, remotely-sensed data and climatic observations, using clearly-defined methods, makes allowance for droughts and global warming. It indicates that 24 per cent of land has suffered declining net primary productivity over the last 25 years; this area is home to a quarter of the world's people. When adjusted for climatic variations, the loss of primary productivity is interpreted as land degradation. In contrast to received wisdom, dry lands don't feature strongly. Forests and croplands are most affected by land degradation and protected areas fare no better than anywhere else. Unprecedented land use change is being driven not only by local processes but also by external pressures related to burgeoning population, economic & technology developments and globalisation; and unsustainable land use is causing land degradation. This suggests a need for a policy shift from desertification in dry lands to land degradation globally, and from environmental protection to developmental initiatives. The paper will discuss potential responses to land degradation that are informed by the new insights into the extent and severity of land degradation globally.

  5. Observing and Quantifying Ecological Disturbance Impacts on Semi-arid Biomes in the Southwestern US.

    Science.gov (United States)

    Litvak, M. E.; Krofcheck, D. J.; Morillas, L.; Fox, A. M.

    2014-12-01

    The magnitude of carbon fluxes through arid and semi-arid ecosystems is considered modest, but integrated over the ~40% of the global land surface covered by these ecosystems, the total carbon stored is almost twice that in temperate forest ecosystems. In the semi-arid Southwestern U.S., drought and rising temperatures have triggered insect outbreaks, fire and widespread mortality in the past 5 years, all of which are predicted to increase in the next century. Understanding how resilient carbon pools and fluxes in these biomes are to these disturbances constitutes a large uncertainty in our ability to understand both carbon and energy flux dynamics in this region. We use an 8 year record (2007-2014) of continuous measurements of net ecosystem exchange of carbon (NEE) and its components (gross primary productivity (GPP) and ecosystem respiration (Re), and evapotranspiration (ET) made over the New Mexico Elevation Gradient (NMEG) network of flux tower sites (desert grassland, creosote shrubland, juniper savanna, piñon-juniper woodland, ponderosa pine and subalpine mixed conifer) to quantify the biome-specific responses of carbon and water dynamics to these disturbances. In particular, we focus on biome-specific responses across the NMEG biomes to the extended drought in this region from 2011-2014, and to the widespread mortality observed in piñon-juniper woodlands following the turn of the century drought (1999-2002) and multi-year recent drought. Finally, we compare functional responses of land-surface fluxes to recent catastrophic fires (grassland, subalpine conifer biomes), and insect outbreaks (subalpine conifer and piñon-juniper woodland biomes). We discuss the results in terms of which disturbances have contributed to and are likely to trigger the largest changes in carbon sequestration in this region in response to predicted climate change scenarios.

  6. Uses of tree legumes in semi-arid regions

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P.

    1980-01-01

    Uses of tree legumes in semi-arid and arid regions are reviewed. This review is divided into sections according to the following general use categories: fuels; human food; livestock food; to increase yields of crops grown beneath their canopies;and control of desertification. (MHR)

  7. Reducción del Consumo Eléctrico y C0(2 mediante Sistemas de Ahorro y de Aislamiento Térmico aplicados a Viviendas en Zonas Áridas de México Electrical Consumption and C0(2 Reduction using Saving Systems and Thermal Insulation applied to Dwellings in Arid Lands of México

    Directory of Open Access Journals (Sweden)

    Roberto Calderón

    2011-01-01

    Full Text Available Se compara los consumos de energía de dos tipos de vivienda, eficiente e ineficiente, determinando su consumo eléctrico y reducción de C0(2, utilizando aislamiento térmico y sistemas de ahorro de energía. El estudio realizado mediante simulación se aplica a tres ciudades áridas de México: Mexicali, Ciudad Obregón y Hermosillo. De la vivienda ineficiente evaluada en las tres ciudades, Mexicali, registró los índices más altos con 7.014 kWh/año, impactando directamente sobre el ingreso familiar, los rangos de confort y la calidad de vida del usuario, además de aportar una cantidad de 4.88 toneladas de emisiones de C0(2 por vivienda al año. Estos indicadores pueden llegar a reducirse en entre el 40 y 50% si la vivienda es eficiente.The energy consumption of two types of dwellings, efficient and inefficient, are analyzed and compared, determining the electrical consumption and C0(2 reduction, utilizing thermal insulation and saving-energy options. The study done by simulation was applied in three arid áreas in México: Mexicali, Baja Obregón and Hermosillo. The results indícate that Mexicali presented the highest consumptions rates with 7.104 kWh/year, affecting directly the family household income, thermal comfort and life quality, besides providing 4.88 tons of C0(2 emission per house per year. These indexes can be reduced by 40 and 50% if the house is efficient.

  8. Advancing the Food-Energy-Water Nexus: Closing Nutrient Loops in Arid River Corridors.

    Science.gov (United States)

    Mortensen, Jacob G; González-Pinzón, Ricardo; Dahm, Clifford N; Wang, Jingjing; Zeglin, Lydia H; Van Horn, David J

    2016-08-16

    Closing nutrient loops in terrestrial and aquatic ecosystems is integral to achieve resource security in the food-energy-water (FEW) nexus. We performed multiyear (2005-2008), monthly sampling of instream dissolved inorganic nutrient concentrations (NH4-N, NO3-N, soluble reactive phosphorus-SRP) along a ∼ 300-km arid-land river (Rio Grande, NM) and generated nutrient budgets to investigate how the net source/sink behavior of wastewater and irrigated agriculture can be holistically managed to improve water quality and close nutrient loops. Treated wastewater on average contributed over 90% of the instream dissolved inorganic nutrients (101 kg/day NH4-N, 1097 kg/day NO3-N, 656 kg/day SRP). During growing seasons, the irrigation network downstream of wastewater outfalls retained on average 37% of NO3-N and 45% of SRP inputs, with maximum retention exceeding 60% and 80% of NO3-N and SRP inputs, respectively. Accurate quantification of NH4-N retention was hindered by low loading and high variability. Nutrient retention in the irrigation network and instream processes together limited downstream export during growing seasons, with total retention of 33-99% of NO3-N inputs and 45-99% of SRP inputs. From our synoptic analysis, we identify trade-offs associated with wastewater reuse for agriculture within the scope of the FEW nexus and propose strategies for closing nutrient loops in arid-land rivers.

  9. Evaluation of Different Soil Salinity Mapping Using Remote Sensing Techniques in Arid Ecosystems, Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Mohamed Elhag

    2016-01-01

    Full Text Available Land covers in Saudi Arabia are generally described as salty soils with sand dunes and sand sheets. Waterlogging and higher soil salinity are major challenges to sustaining agricultural practices in Saudi Arabia principally within closed drainage basins. Agricultural practices in Saudi Arabia were flourishing in the last two decades. The newly reclaimed lands were added annually and distributed all over the country. Irrigation techniques are mostly modernized to fulfill water saving strategies. Nevertheless, water resources in Saudi Arabia are under stress and groundwater levels are depleted rapidly due to heavy abstraction that may exceed crop water requirements in most of the cases due to high evaporation rates. The excess use of irrigational water leads to severe soil salinity problems. Applications of remote sensing technique in agricultural practices became widely distinctive and cover multidisciplinary principal interests on both local and regional levels. The most important remote sensing applications in agricultural practices are vegetation indices which are related to vegetation and water especially in an arid environment. Soil salinity mapping in an arid ecosystem using remote sensing data is a demanding task. Several soil salinity indices were implemented and evaluated to detect soil salinity effectively and quantitatively. Thematic maps of soil salinity were satisfactorily produced and assessed.

  10. CHARACTERISTICS AND CONSTRUCTION OF LANDSCAPE???ECOLOGY IN ARID REGIONS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    This paper analyzes the characteristics of the landscape structures and landacape ecological processes in arid regions of China. Landscape structure is simplicity and homogeneity with the pattern of desert-oasis-river and canal corridor. The spatial distribution of landscape heterogeneity mosaics is relatively dependent on water resources. In arid regions,the landscape changes rapidly and extensively because of the sensitive landscape ecosystems and fragile regional ecosystems.For the sustainable development of arid regions, the theories and methods for the eco-environmental construction and the strategies of ecological construction in the arid regions were proposed in the view of landscape ecology. Keynote subjects of landscape ecology were also discussed. The paper points out that protecting and increasing landscape diversity and heterogeneity are critical to control ecological safety in arid regions.

  11. Where does blue water go in the semi-arid area of northern China under changing environments?

    Science.gov (United States)

    Ren, L.; Yuan, F.; Yong, B.; Jiang, S.; Yang, X.; Gong, L.; Ma, M.; Liu, Y.; Shen, H.

    2014-09-01

    River flow regimes in the semi-arid region of northern China show a decreasing trend in terms of quantity. River runoff (i.e. blue water) reduction within the Laohahe catchment, the source area of the Liaohe River basin, manifests the aridity that exists widely in northern China. According to the water balance equation, during the past half-century, observed streamflow records in the Laohahe catchment show that blue water was re-directed to green water flow (i.e. evapotranspiration) over annual and decadal time scales, whereas precipitation did not vary much. Human activities and land-use/land-cover changes are the fundamental reasons for such runoff change. In the studied catchment, extensive land reclamation for agriculture, water withdrawal from streams, and abstraction from aquifers for irrigation are the direct and main causes leading to the decrease in observed blue water. These factors further demonstrate that a land-use decision is also a decision about water. Therefore, there is a need for an integrated modelling framework to intrinsically link climate, hydrological, and agricultural models with social and economic analyses.

  12. Long-term aridity changes in the western United States.

    Science.gov (United States)

    Cook, Edward R; Woodhouse, Connie A; Eakin, C Mark; Meko, David M; Stahle, David W

    2004-11-01

    The western United States is experiencing a severe multiyear drought that is unprecedented in some hydroclimatic records. Using gridded drought reconstructions that cover most of the western United States over the past 1200 years, we show that this drought pales in comparison to an earlier period of elevated aridity and epic drought in AD 900 to 1300, an interval broadly consistent with the Medieval Warm Period. If elevated aridity in the western United States is a natural response to climate warming, then any trend toward warmer temperatures in the future could lead to a serious long-term increase in aridity over western North America.

  13. Federal Lands

    Data.gov (United States)

    Department of Homeland Security — This map layer consists of federally owned or administered lands of theUnited States, Puerto Rico, and the U.S. Virgin Islands. Only areas of 640 acres or more are...

  14. Land Resources

    Science.gov (United States)

    Young, Anthony

    1998-08-01

    Unless action is taken, the developing world will face recurrent problems of food security and conflict. This volume provides a summary and perspective of the field of land resources and suggests improvements needed to conserve resources for future generations. Coverage provides an authoritative review of the resources of soils, water, climate, forests and pastures on which agriculture depends. It assesses the interactions between land resources and wider aspects of development, including population and poverty. It provides a strong critique of current methods of assessing land degradation and placing an economic value on land. It should be read by all involved in rural development, including scientists, economists, geographers, sociologists, planners, and students of development studies.

  15. Contribution of semi-arid ecosystems to interannual variability of the global carbon cycle.

    Science.gov (United States)

    Poulter, Benjamin; Frank, David; Ciais, Philippe; Myneni, Ranga B; Andela, Niels; Bi, Jian; Broquet, Gregoire; Canadell, Josep G; Chevallier, Frederic; Liu, Yi Y; Running, Steven W; Sitch, Stephen; van der Werf, Guido R

    2014-05-29

    The land and ocean act as a sink for fossil-fuel emissions, thereby slowing the rise of atmospheric carbon dioxide concentrations. Although the uptake of carbon by oceanic and terrestrial processes has kept pace with accelerating carbon dioxide emissions until now, atmospheric carbon dioxide concentrations exhibit a large variability on interannual timescales, considered to be driven primarily by terrestrial ecosystem processes dominated by tropical rainforests. We use a terrestrial biogeochemical model, atmospheric carbon dioxide inversion and global carbon budget accounting methods to investigate the evolution of the terrestrial carbon sink over the past 30 years, with a focus on the underlying mechanisms responsible for the exceptionally large land carbon sink reported in 2011 (ref. 2). Here we show that our three terrestrial carbon sink estimates are in good agreement and support the finding of a 2011 record land carbon sink. Surprisingly, we find that the global carbon sink anomaly was driven by growth of semi-arid vegetation in the Southern Hemisphere, with almost 60 per cent of carbon uptake attributed to Australian ecosystems, where prevalent La Niña conditions caused up to six consecutive seasons of increased precipitation. In addition, since 1981, a six per cent expansion of vegetation cover over Australia was associated with a fourfold increase in the sensitivity of continental net carbon uptake to precipitation. Our findings suggest that the higher turnover rates of carbon pools in semi-arid biomes are an increasingly important driver of global carbon cycle inter-annual variability and that tropical rainforests may become less relevant drivers in the future. More research is needed to identify to what extent the carbon stocks accumulated during wet years are vulnerable to rapid decomposition or loss through fire in subsequent years.

  16. Assessment of the Consistency among Precipitation Products over Arid Regions

    Science.gov (United States)

    Ghebreyesus, Dawit; Temimi, Marouane

    2016-04-01

    This study addresses the analysis of the consistency among global precipitation products over arid regions. First, precipitation products were examined against in situ observations from the UAE network. Then, the consistency among the different products was assessed regionally over the Arabian Peninsula and the Sahara Desert. Four distinct independently-derived precipitation products, namely, Global Precipitation Climate Center (GPCC), Willmott-Matsuura 2001 (WM), Tropical Rainfall Measurement Mission (TRMM), and CPC Morphing (CMORPH) were examined. Over the UAE, in situ monthly observations from 6 stations over a time period of 11 years, from 2000 to 2010 inclusive, were used. The correlation with in situ observations, Root Mean Square Error (RMSE), and Relative Bias (rBIAS) were calculated to evaluate the precipitation products. The lowest areal averaged RMSE over all stations, ranging from 3.82mm to 9.98mm, was obtained with the GPCC indicating a higher agreement with in situ observations. The average RMSE of GPCC over the country was 6.18mm. However, the highest areal averaged RMSE, ranging from 9.44 to 19.52mm, was obtained with the WM product with average of 13.57mm. The results showed an overestimation of the observed rainfall values across all products with overall average of 42%. CMORPH product was found to be the most inconsistent products spatially across the UAE with rBIAS ranging from -47% in Al Ain to 372% in Dubai. The correlation with in situ observations was found to be higher with GPCC product ranging from 0.8450 to 0.9494. TRMM was second with an average of 0.8413, ranging from 0.7098 to 0.9248. Furthermore, Mean Relative Difference (MRD) was calculated to investigate the precision among the precipitation products. CMORPH was found to be inconsistent spatially being the lowest estimator for four stations (Adu Dhabi, Al Ain, Sharjah, Ras Al Khaimah) whereas being the highest estimator for the rest two stations (Dubai and Fujairah). Generally, the

  17. Land use/land cover change and their effects on landscape patterns in the Yanqi Basin, Xinjiang (China).

    Science.gov (United States)

    Wang, Shuixian; Wang, Shengli

    2013-12-01

    Human modification of land use and land cover change (LUCC) drives the change of landscape patterns and limits the availability of products and services for human and livestock. LUCC can undermine environmental health. Thus, this study aimed to develop an understanding of LUCC in the Yanqi Basin, Xinjiang, China, an arid area experiencing dramatic water and land resource use. A time series of satellite images (1964, 1973, 1989, 1999, and 2009) were used to calculate the index of landscape patterns to study the processes involved in changes to land uses and landscape patterns and the influence of this changes on landscape patterns. The results show that land uses in the Yanqi Basin have changed dramatically since 1964 with grassland being mainly converted to cropland. Landscape fragmentation and diversity have decreased in the study area, although landscape fragmentation increased from 1964 to 1999 and then decreased by 2009. The index of landscape diversity decreased from 1.64 in 1964 to 0.71 in 2009. The heterogeneity and complexity of the landscape increased during this period. In contrast, the index of dominance decreased from 0.85 in 1964 to 0.83 in 2009. Land use change drives landscape patterns of the development of the watershed toward diversity and a fragmented structure. Population growth, economic development, and industrial policies were the dominant driving forces behind LUCC in the Yanqi Basin. Sustainable use of land resources is a significant factor in maintaining economic development and environmental protection in this arid inland river basin.

  18. Analysis of Changing Land Use Land Cover in Salinity Affected Coastal Region

    Directory of Open Access Journals (Sweden)

    Vikrant Vijay Singh

    2016-04-01

    Full Text Available Anthropogenic activities have induced many changes in land use over a period of three decades in a salinity affected semi-arid region of coastal Saurashtra in Gujarat. To overcome water scarcity and quality issues, efforts have been undertaken by state authorities to conserve and effectively use surface water resource to supplement the irrigation and domestic water requirements. Surface water schemes implemented in the area have altered the general land use conditions. In the present study, remotely sensed data coupled with ancillary data are used for analysing the land use-land cover change. Supervised classification and post classification techniques are employed to classify various land use-land cover classes and to detect changes, respectively. Landscape pattern change has been studied by analysing the spatial pattern of land use land cover classes structure. The results show that the region has experienced significant changes over a thirty year period. Growth in agricultural activities, policies developed to conserve freshwater runoff, and increase in built-up area, are the main driving forces behind these changes.

  19. Soil biogenic emissions of nitric oxide from a semi-arid savanna in South Africa

    Science.gov (United States)

    Feig, G. T.; Mamtimin, B.; Meixner, F. X.

    2008-12-01

    Soils of arid and semi-arid ecosystems are important biogenic sources of atmospheric nitric oxide (NO), however, there is still a shortage of measurements from these systems. Here we present the results of a laboratory study of the biogenic emission of NO from four different landscape positions of the Kruger National Park (KNP), a large conservation area in a semi-arid region of South Africa. Results show that the highest net potential NO fluxes come from the low lying (footslope) landscape regions, which have the largest nitrogen stocks and highest rates of nitrogen input into the soil. Net potential NO fluxes from midslope and crest regions were considerably lower. The maximum release of NO occurred at fairly low soil moisture contents of 10%-20% water filled pore space. Using soil moisture and temperature data obtained in situ at the Kruger National Park flux tower site, net potential NO fluxes obtained in the laboratory were converted to field fluxes for each of the four landscape positions for the period 2003 to 2005. The highest field NO flux is from footslope positions, during each of these years and emissions ranged from 1.5-8.5 kg ha a (in terms of mass of nitrogen). Remote sensing and Geographic Information Systems techniques were used to up-scale field NO fluxes on a regional basis indicating that the highest emissions occurred from the midslope positions, due to their large geographical extent in the considered research area. Emissions for the KNP Skukuza land type (56 000 ha) ranged from 20×103 kg in 2004 to 34×103 kg in 2003. The importance of landscape characteristics in the determination of regional biogenic NO soil emission is emphasized.

  20. Impacts of Climate Anomalies on the Vegetation Patterns in the Arid and Semi-Arid Zones of Uzbekistan

    Science.gov (United States)

    Dildora, Aralova; Toderich, Kristina; Dilshod, Gafurov

    2016-08-01

    Steadily rising temperature anomalies in last decades are causing changes in vegetation patterns for sensitive to climate change in arid and semi-arid dryland ecosystems. After desiccation of the Aral Sea, Uzbekistan has been left with the challenge to develop drought and heat stress monitoring system and tools (e.g., to monitor vegetation status and/crop pattern dynamics) with using remote sensing technologies in broad scale. This study examines several climate parameters, NDVI and drought indexes within geostatistical method to predict further vegetation status in arid and semi-arid zones of landscapes. This approaches aimed to extract and utilize certain variable environmental data (temperature and precipitation) for assessment and inter-linkages of vegetation cover dynamics, specifically related to predict degraded and recovered zones or desertification process in the drylands due to scarcity of water resources and high risks of climate anomalies in fragile ecosystem of Uzbekistan.

  1. Late glacial aridity in southern Rocky Mountains

    Energy Technology Data Exchange (ETDEWEB)

    Davis, O.K.; Pitblado, B.L. [Univ. of Arizona, Tucson, AZ (United States)

    1995-09-01

    While the slopes of the present-day Colorado Rocky Mountains are characterized by large stands of subalpine and montane conifers, the Rockies of the late glacial looked dramatically different. Specifically, pollen records suggest that during the late glacial, Artemisia and Gramineae predominated throughout the mountains of Colorado. At some point between 11,000 and 10,000 B.P., however, both Artemisia and grasses underwent a dramatic decline, which can be identified in virtually every pollen diagram produced for Colorado mountain sites, including Como Lake (Sangre de Cristo Mountains), Copley Lake and Splains; Gulch (near Crested Butte), Molas Lake (San Juan Mountains), and Redrock Lake (Boulder County). Moreover, the same pattern seems to hold for pollen spectra derived for areas adjacent to Colorado, including at sites in the Chuska Mountains of New Mexico and in eastern Wyoming. The implications of this consistent finding are compelling. The closest modem analogues to the Artemisia- and Gramineae-dominated late-glacial Colorado Rockies are found in the relatively arid northern Great Basin, which suggests that annual precipitation was much lower in the late-glacial southern Rocky Mountains than it was throughout the Holocene.

  2. Remote sensing-based vegetation indices for monitoring vegetation change in the semi-arid region of Sudan

    Science.gov (United States)

    R. A., Majdaldin; Osunmadewa, B. A.; Csaplovics, E.; Aralova, D.

    2016-10-01

    Land degradation, a phenomenon referring to (drought) in arid, semi-arid and dry sub-humid regions as a result of climatic variations and anthropogenic activities most especially in the semi-arid lands of Sudan, where vast majority of the rural population depend solely on agriculture and pasture for their daily livelihood, the ecological pattern had been greatly influenced thereby leading to loss of vegetation cover coupled with climatic variability and replacement of the natural tree composition with invasive mesquite species. The principal aim of this study is to quantitatively examine the vigour of vegetation in Sudan through different vegetation indices. The assessment was done based on indicators such as soil adjusted vegetation index (SAVI). Cloud free multi-spectral remotely sensed data from LANDSAT imagery for the dry season periods of 1984 and 2009 were used in this study. Results of this study shows conversion of vegetation to other land use type. In general, an increase in area covered by vegetation was observed from the NDVI results of 2009 which is a contrast of that of 1984. The results of the vegetation indices for NDVI in 1984 (vegetated area) showed that about 21% was covered by vegetation while 49% of the area were covered with vegetation in 2009. Similar increase in vegetated area were observed from the result of SAVI. The decrease in vegetation observed in 1984 is as a result of extensive drought period which affects vegetation productivity thereby accelerating expansion of bare surfaces and sand accumulation. Although, increase in vegetated area were observed from the result of this study, this increase has a negative impact as the natural vegetation are degraded due to human induced activities which gradually led to the replacement of the natural vegetation with invasive tree species. The results of the study shows that NDVI perform better than by SAVI.

  3. Water from air: An overlooked source of moisture in arid and semiarid regions

    Science.gov (United States)

    McHugh, Theresa; Morrissey, Ember M; Reed, Sasha C.; Hungate, Bruce A.; Schwartz, Egbert

    2015-01-01

    Water drives the functioning of Earth’s arid and semiarid lands. Drylands can obtain water from sources other than precipitation, yet little is known about how non-rainfall water inputs influence dryland communities and their activity. In particular, water vapor adsorption – movement of atmospheric water vapor into soil when soil air is drier than the overlying air – likely occurs often in drylands, yet its effects on ecosystem processes are not known. By adding 18O-enriched water vapor to the atmosphere of a closed system, we documented the conversion of water vapor to soil liquid water across a temperature range typical of arid ecosystems. This phenomenon rapidly increased soil moisture and stimulated microbial carbon (C) cycling, and the flux of water vapor to soil had a stronger impact than temperature on microbial activity. In a semiarid grassland, we also observed that non-rainfall water inputs stimulated microbial activity and C cycling. Together these data suggest that, during rain-free periods, atmospheric moisture in drylands may significantly contribute to variation in soil water content, thereby influencing ecosystem processes. The simple physical process of adsorption of water vapor to soil particles, forming liquid water, represents an overlooked but potentially important contributor to C cycling in drylands.

  4. Landscape eco-environment risk assessment of highway in arid area of Xinjiang,China

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    With the aid of analyses to landscape ecology in the highway region of the arid area in Xinjiang of China, vegetation type, soil type and land-use type were ascertained as environmental factors of highway landscape ecosystem fragility, and seasonal flood, blown-wind sand and alkali-salinization as disaster factors of highway engineering. All items of these factors constitute an objective hierarchy of evaluating landscape ecosystem risk of the highway region in the arid area. The weighted values of the items were determined according to the number of occupied area or length by them against each unit. The area or length was interpreted with the aids of GIS technology and gained by measuring in the highway reconnaissance. The results of the eco-environmental risk assessment of G315 Yitunbulake-Qiemo section in Xinjiang shows that eight units of landscape ecology can be sorted into four categories according to the differences of the fragility indices (Σxiwi) and the disaster indices (Σyiwj).

  5. Effects of aridity in controlling the magnitude of runoff and erosion after wildfire

    Science.gov (United States)

    Noske, Philip J.; Nyman, Petter; Lane, Patrick N. J.; Sheridan, Gary J.

    2016-06-01

    This study represents a uniquely high-resolution observation of postwildfire runoff and erosion from dry forested uplands of SE Australia. We monitored runoff and sediment load, and temporal changes in soil surface properties from two (0.2-0.3 ha) dry forested catchments burned during the 2009 Black Saturday wildfire. Event-based surface runoff to rainfall ratios approached 0.45 during the first year postwildfire, compared to reported values forests were attributed to wildfire-induced soil water repellency and inherently low hydraulic conductivity. Mean ponded hydraulic conductivity ranged from 3 to 29 mm h-1, much lower than values commonly reported for wetter forest. Annual sediment yields peaked at 10 t ha-1 during the first year before declining dramatically to background levels, suggesting high-magnitude erosion processes may become limited by sediment availability on hillslopes. Small differences in aridity between equatorial and polar-facing catchments produced substantial differences in surface runoff and erosion, most likely due to higher infiltration and surface roughness on polar-facing slopes. In summary, the results show that postwildfire erosion processes in Eucalypt forests in south-east Australia are highly variable and that distinctive response domains within the region exist between different forest types, therefore regional generalizations are problematic. The large differences in erosion processes with relatively small changes in aridity have large implications for predicting hydrologic-driven geomorphic changes, land degradation, and water contamination through erosion after wildfire across the landscape.

  6. Entomological studies for surveillance and prevention of dengue in arid and semi-arid districts of Rajasthan, India

    Directory of Open Access Journals (Sweden)

    Anil Purohit

    2008-05-01

    Full Text Available Background & objectives: Rajasthan is one of the dengue endemic states of India. Very few studies have been published on entomological aspects of dengue in this state. Owing to water scarcity, inhabitants in desert areas overstore domestic water which leads to the persistence of dengue vectors within the domestic premises. Area specific knowledge on breeding, key containers and seasonal rhythms of vector population is essential for preparing an effective prevention plan against dengue. Present paper reports results of entomological investigations on dengue vectors in arid and semi-arid districts of Rajasthan. Methods: Longitudinal studies were undertaken during 2004–06 in one arid and two semi-arid dengue endemic districts of Rajasthan. Adult and larval Aedes were collected from the randomly selected houses in representative towns and villages with associated details of container types and water storage practices of inhabitants. Results: In urban areas during all the seasons adult house index (AHI of Aedes aegypti was maximum in desert zone (25 and least in semi-arid area with saline river III (1. The difference of AHI during three seasons was statistically significant (c2 = 16.1, p <0.01 for urban; and c2 = 50.71, p < 0.001 for rural. Breeding of Ae. aegypti among urban settings was maximum in desert zone. During all the seasons cement tanks were the key breeding habitats for Ae. aegypti in desert as well as semi-arid areas. Interpretation & conclusion: Water storage habits during summer season emerged to be the risk factor of vector abundance in urban areas of arid and semi-arid settings. A carefully designed study of key containers targeting cement tanks as the primary habitats of mosquito control may lead to commendable results for dengue prevention.

  7. Keeping Sediment and Nutrients out of Streams in Arid/Semi-Arid Regions: Application of Low Impact Development/Green Infrastructure Practices

    Science.gov (United States)

    Yongping, Yuan

    2015-04-01

    Climatic and hydrological characteristics in the arid/semi-arid areas create unique challenges to soil, water and biodiversity conservation. These areas are environmentally sensitive, but very valuable for the ecosystems services they provide to society. Some of these areas are experiencing the fastest urbanization and now face multiple water resource challenges. Low Impact Development (LID)/Green Infrastructure (GI) practices are increasingly popular for reducing stormwater and nonpoint source pollution in many regions around the world. However, streamflow in the arid/semi-arid regions is largely dependent on seasonal, short term, and high intensity rainfall events. LID has not been very common in the arid/semi-arid regions due to a lack of performance evaluation, as well as the perception that LID may not be very useful for regions with little annual precipitation. This study focused on investigating the hydrologic and pollutant removal performance of LID/GI systems in arid/semi-arid climates. Ten types of practices were found in use in the Western/Southwestern U.S.: rainwater harvest systems, detention ponds, retention ponds, bioretention, media filters, porous pavements, vegetated swales/buffer/strips, green roofs, infiltration trenches, and integrated LIDs. This study compared the performance of these practices in terms of their effectiveness at pollutant removal and cost-effectiveness. This analysis provides insight into the future implementation of LID/GI in the arid/semi-arid areas. Key words: LID/GI, arid/semi-arid, effectiveness of pollutant removal, cost-effectiveness analysis

  8. Las unidades ambientales homogéneas como herramienta para la ordenación territorial y la caracterización de litorales áridos / Use of Homogeneous Environmental Management Units as a Tool for Land-Use Planning and Characterization of Arid Coasts

    Directory of Open Access Journals (Sweden)

    Javier Camino Dorta

    2014-12-01

    Full Text Available En Canarias, en las últimas dos décadas se ha generalizado en la actividad de ordenación territorial el empleo de las denominadas unidades de diagnóstico, que fueron reguladas en 1995 por el Decreto 35/95 de Evaluación Ambiental (hoy derogado. Las unidades ambientales homogéneas se han convertido en una herramienta del planificador. La validez de las mismas, los problemas y ventajas que ofrecen en la práctica, es analizada en este artículo de cara a la ordenación y gestión litorales. Desde la praxis se valora la eficacia de esta metodología en las costas orientales de Canarias y su posible extrapolación a otros territorios continentales, comprobando su validez y eficacia en las cercanas costas saharianas y su espacio litoral.In the Canary Islands, the use of so-called diagnostic units, has been widespread in the activity of land usein the last two decades. These diagnostic units were regulated in 1995 by Decree 35/95 of Environmental Assessment (now repealed. Homogenous environmental management units have become a tool for planners. Their validity, problems and advantages are analyzed in this paper for coastal planning and management. In practice, effectiveness of this methodology on the eastern coasts of the Canary Islands and its possible extrapolation to other mainland regions is assessed by checking its validity and effectiveness in nearby Saharan coasts and coastal areas.

  9. Soil erosion and land degradation in the Highlands of Jordan

    Science.gov (United States)

    Khresat, Saeb

    2013-04-01

    The Highlands of Jordan has a Mediterranean type of climate characterized by hot dry summers and cold wet winters. Unsustainable land use practices, recurrent droughts and climate change are the main causes of land degradation in the Highlands area of Jordan. Unsustainable land use practices include improper plowing, inappropriate rotations, inadequate or inexistent management of plant residues, overgrazing of natural vegetation, forest cutting, land fragmentation and over-pumping of groundwater. In addition, Jordan's rapid population growth (2.8% per year) is exerting considerable pressure upon its limited arable land through uncontrolled and random urbanization activities. Water erosion is the most widespread Land degradation type in the country. It greatly increases on slopes where the vegetation cover is (seasonally) reduced. It is further aggravated by a loss of soil structure and reduced infiltration rates. Wind erosion occurs most frequently in the arid and semi-arid portions of the southern Highlands, especially in areas with sandy or loamy soils. Rangeland degradation is the second most widespread land degradation type that is driven by overgrazing. The impact of overgrazing on the vegetation is evident from the excessive uprooting of the green matter (grass and bushes), leading to reduced seeding, reduced regeneration, and the consequent loss of plant cover which make the soil more susceptible to water and wind erosion. It is estimated that about 41 percent of Jordan's total land area is characterized as degraded of which 22 percent of the total land mass is classified as moderately degraded and agricultural productivity is greatly reduced. Observed aspects of land degradation include the recession of forest areas, high rate of erosion by water (formation of rills and gullies), expansion of urbanized area, reduction in soil organic matter and soil structure deterioration. Implementation of soil erosion control measures such as contour cultivation

  10. Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Emmanuel Mavhura

    2015-02-01

    Full Text Available Small-scale rain-fed agriculture is the main livelihood in arid to semi-arid regions of subSaharan Africa. The area is characterised by erratic rainfall and frequent droughts, making the capacity for coping with temporal water shortages essential for smallholder farmers. Focusing on the Zambezi Valley, Zimbabwe, this study investigates the impact of drought on food security and the strategies used by smallholder farmers to cope with drought. We used meteorological data and interviews to examine the rainfall variability in the study area and the drought-coping mechanisms employed by smallholder famers respectively. The results show that there are various strategies used by smallholder farmers to cope with the impact of drought. These strategies include drought-tolerant crop production, crop variety diversification, purchasing cereals through asset sales, non-governmental organisations’ food aid and gathering wild fruit. However, consecutive droughts have resulted in high food insecurity and depletion of household assets during droughts. Smallholder farmers in the valley have also resorted to a number of measures taken before, during and after the drought. Still, these strategies are not robust enough to cope with this uncertainty

  11. Modelling the effects of land-use and land-cover change on water availability in the Jordan River region

    Directory of Open Access Journals (Sweden)

    R. Schaldach

    2009-08-01

    Full Text Available Within the GLOWA Jordan River project, a first-time overview of the current and possible future land and water conditions of a major part of the Eastern Mediterranean region (ca. 100 000 km2 is given. First, we applied the hydrological model TRAIN to simulate current water availability (runoff and groundwater recharge and irrigation water demand on a 1 km×1 km spatial resolution. The results demonstrate the scarcity of water resources in the study region, with extremely low values of water availability in the semi-arid and arid parts. Then, a set of four divergent scenarios on the future of water has been developed using a stakeholder driven approach. Relevant drivers for land-use/land-cover change were fed into the LandSHIFT.R model to produce land-use and land-cover maps for the different scenarios. These maps were used as input to TRAIN in order to generate scenarios of water availability and irrigation water demand for the region. For this study, two intermediate scenarios were selected, with projected developments ranging between optimistic and pessimistic futures (with regard to social and economic conditions in the region. Given that climate conditions remain unchanged, the simulations show both increases and decreases in water availability, depending on the future pattern of natural and agricultural vegetation and the related dominance of hydrological processes.

  12. DNA barcoding of arid wild plants using rbcL gene sequences.

    Science.gov (United States)

    Bafeel, S O; Arif, I A; Bakir, M A; Al Homaidan, A A; Al Farhan, A H; Khan, H A

    2012-07-19

    DNA barcoding is currently gaining popularity due to its simplicity and high accuracy as compared to the complexity and subjective biases associated with morphology-based identification of taxa. The standard chloroplast DNA barcode for land plants recommended by the Consortium for the Barcode of Life (CBOL) plant working group needs to be evaluated for a wide range of plant species. We therefore tested the potential of the rbcL marker for the identification of wild plants belonging to diverse families of arid regions. Maximum likelihood tree analysis was performed to evaluate the discriminatory power of the rbcL gene. Our findings showed that using rbcL gene sequences enabled identification of the majority of the samples (92%) to genus level and only 17% to species level.

  13. Estimating sagebrush cover in semi-arid environments using Landsat Thematic Mapper data

    Science.gov (United States)

    Sivanpillai, Ramesh; Prager, Steven D.; Storey, Thomas O.

    2009-04-01

    Sagebrush ecosystems of the western US provide important habitat for several ungulate and vertebrate species. As a consequence of energy development, these ecosystems in Wyoming have been subjected to a variety of anthropogenic disturbances. Land managers require methodology that will allow them to consistently catalog sagebrush ecosystems and evaluate potential impact of proposed anthropogenic activities. This study addresses the utility of remotely sensed and ancillary geospatial data to estimate sagebrush cover using ordinal logistic regression. We demonstrate statistically significant prediction of ordinal sagebrush cover categories using spectral ( χ2 = 113; p < 0.0001) and transformed indices ( χ2 = 117; p < 0.0001). Both Landsat spectral bands ( c-value = 0.88) and transformed indices ( c-value = 0.89) can distinguish sites with closed, moderate and open cover sagebrush cover categories from no cover. The techniques described in this study can be used for estimating categories of sagebrush cover in arid ecosystems.

  14. Preliminary reconstruction of the desert and sandy land distributions in China since the last interglacial period

    Institute of Scientific and Technical Information of China (English)

    CHEN; Huizhong; SU; Zhizhu; YANG; Ping; DONG; Guangrong

    2004-01-01

    The desert and sandy land are the products of arid climate. The spatial distribution of modern deserts and sandy land in China and their relation to climate show following characteristics: arid and hyper-arid desert zones, at isohyet of less than 200 mm, are dominated by mobile dunes; semi-arid steppe and arid desert steppe with the precipitation between 200-400mm, are dominated by semi-fixed and fixed sand dunes; the precipitation of sub-humid forest grassland and humid forest zones with scattered fixed sand land is higher than 400 mm. With this as reference, in combination with considerable amount of paleoclimatic data in desert regions and adjacent regions, the distributions of desert and sandy land in China during the last interglacial period, the last glacial maximum (LGM), and the Holocene megathermal, were preliminarily reconstructed. The results compared with that of today show that the distribution of desert and sandy land in China was greatly dwindled during last interglacial period, and the mobile dune area was about two-thirds of that of today's, but greatly expanded during LGM. However, the dwindling area of desert and sandy land in the Holocene megathermal was smaller than that in the last interglacial period. The forcing mechanism was mainly related to the changes of East Asian winter and summer monsoon, south-northward swing of the westerlies and the variations of the Qinghai-Tibet Plateau monsoon intensity caused by global climate changes during the cold and warm intervals since the last interglacial period.

  15. Simulation of CO2 and sensible/latent heat fluxes exchange between land surface and atmosphere over cropland and grassland in semi-arid region, China%半干旱区农田和草地与大气间二氧化碳和水热通量的模拟研究

    Institute of Scientific and Technical Information of China (English)

    姜纪峰; 延晓冬; 黄耀; 郭维栋; 刘辉志

    2007-01-01

    集成生物圈模型(IBIS)是目前最复杂的基于动态植被模型的陆面生物物理模型之一.应用该模型对国际CEOP计划半干旱区基准站之一的吉林通榆观测站(44°25'N , 122°52'E)草地和农田生态系统2003年全年的CO2和水、热通量变化进行模拟,并将结果与涡度相关法测定的观测值进行了对比分析,以检验IBIS模型在半干旱区的模拟能力.对比结果表明:除CO2通量模拟结果不够理想外,IBIS模型较好地模拟了通榆观测站的感热通量和潜热通量.总体上看,该模型对农田生态系统模拟的偏差小于对退化草地的模拟.%A comparison between simulated land surface fluxes and observed eddy covariance (EC) measurements was conducted to validate Integrated Biosphere Simulator (IBIS) at Tongyu field observation station (44°25'N, 122°52'E) in Jilin Province, China. Results showed that the IBIS model could reproduce net ecosystem CO2 exchange (NEE), sensible and latent heat fluxes reasonably, as indicated by correlation coefficients exceeding the significant level of 0.05. It was also evident that the NEE and sensible heat fluxes were characterized by diurnal and seasonal variation both in the grassland and the cropland ecosystems, while the latent heat fluxes correlated with evapotranspiration, only took on the diurnal variation during the growing season. Moreover, both sensible heat fluxes and the latent heat fluxes were larger in the cropland ecosystem than that in the degraded grassland ecosystem. This different characteristic was possibly correlated with vegetation growing situation in the two kinds of ecosystems. A close agreement between observation and simulation on NEE, sensible heat fluxes and latent heat flux was obtained both in the degraded grassland and the cropland ecosystems. In addition, the annual NEE in the model was overestimated by 23.21% at the grassland and 27.43% at the cropland, sensible heat flux with corresponding 9.90% and 11

  16. Assessment of overland flow variation and blue water production in a farmed semi-arid water harvesting catchment

    Science.gov (United States)

    Mekki, I.; Albergel, J.; Ben Mechlia, N.; Voltz, M.

    Upgrading agriculture in semi-arid areas and ensuring its sustainability require an optimal management of rainfall partition between blue and green waters in the farmed water harvesting catchment. The main objective of this study is to analyze the influence of heterogeneous land use on the spatial and temporal variation of rainfall partitioning and blue water production within a typical farmed catchment located in north-eastern Tunisia. The catchment has an area of 2.6 km 2 and comprises at its outlet a dam, which retains the runoff water in a reservoir. Overland flow and soil water balance components were monitored during two cropping seasons (2000/2001 and 2001/2002) on a network of eleven plots of 2 m 2 each with different land use and soil characteristics. The hydrological balances of both the catchment and reservoir have been monitored since 1994. Observed data showed a very large temporal and spatial variability of overland flow within the catchment reflecting the great importance of total rainfall as well as land use. During the 2001/2002 season the results showed a large variation of the number of observed runoff events, from 27 to 39, and of the annual overland flow depths, from 8 mm (under vineyard on calcaric cambisols) up to 43 mm (under shrubs-pasture on haplic regosols), between the plots. The annual runoff amounts were moderate; they always corresponded to less than 15% of the annual rainfall amount whatever the observation scale. It was also observed that changes in land use in years with similar rainfall could lead to significant differences in blue water flow. An attempt for predicting the overland flow by the general linear regression approach showed an r2 of 31%, the predictors used are the class of soil infiltration capacity, the initial moisture saturation ratio of the soil surface layer and the total rainfall amounts. These experimental results indicate that the variation in land use in a semi-arid catchment is a main factor of variation in

  17. Extracting change information of land-use and soil-erosion based on RS & GIS technology

    Institute of Scientific and Technical Information of China (English)

    LI Zhong-feng; LI You-cai

    2007-01-01

    Rapid land-use change has taken place in many arid regions of China such as Yulin prefecture over the last decade due to rehabilitation measures. Land-use change and soil erosion dynamics were investigated by the combined use of remote sensing and geographic information systems (GIS). The objectives were to determine land-use transition rates and soil erosion change in Yulin prefecture over 15 years from 1986 to 2000. Significant changes in land-use and soil erosion occurred in the area over the study period. The results show the significant decrease in barren land mainly due to conversion to grassland. Agricultural land increased associated with conversions from grassland and barren land. The area of water erosion and wind erosion declined. The study demonstrates that the integration of satellite remote sensing and GIS is an effective approach for analyzing the direction, rate, and spatial pattern of land-use and soil erosion change.

  18. Nebkha patterns in semi-arid environments

    Science.gov (United States)

    Nield, J. M.; Gillies, J. A.; Nickling, W. G.

    2014-12-01

    In semi-arid supply-limited, environments, nehbka dunes typically form through ecogeomorphic feedbacks. The size, shape and orientation of these dunes are controlled by the interactions between vegetation growth and aeolian sedimentations processes. Once established, these dune patterns modify sediment transport and often form streets of bare surfaces between dune corridors. We examine typical dune and vegetation patterns that form with varying amounts of sediment availability and nebkha maturity at Jornada in the Chihuahuan Desert, New Mexico, USA using terrestrial laser scanning (TLS) to separate the plant and sand elements. Manual and automated TLS shrub height extractions compare well at all sites (p = 0.48-0.94) enabling the quantification of both solid and plant roughness element components in three dimensions. We find that there is a switch in orientation of the dune elements with respect to dominant wind direction from perpendicular to parallel as the landscape develops from an incipient to mature configuration and mesquite-nebkha streets are enhanced. As the nebkha dunes develop the surface coverage of bare sand increases and dune surfaces exceed the size of their companion shrubs. Roughness density also increases at the mature dune site. Individual shrub orientations remain similar at each site, but nebkhas typically host multiple shrub crowns at the mature site. Over a two year period up to 20 cm of erosion was measured on the upwind faces of the mature nebkha dunes, in agreement with the dominant annual wind direction. However, deposition patterns were more diffuse and influenced by the vegetation patterns. This study highlights the importance of ecogeomorphic interactions in shaping nebkha landscape patterns.

  19. The use of soil quality indicators to assess soil functionality in restored semi-arid ecosystems

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Erickson, Todd E.; Dixon, Kingsley W.; Merritt, David J.

    2016-04-01

    Keywords: Pilbara, 1-day CO2 test, microbial activity, mine restoration, soil health, ecosystem services. Introduction Semi-arid and arid environments are highly vulnerable to land degradation and their restoration has commonly showed low rates of success (James et al., 2013). A systematic knowledge of soil functionality is critical to successful restoration of degraded ecosystems since approximately 80% of ecosystem services can be connected to soil functions. The assessment of soil functionality generally involves the evaluation of soil properties and processes as they relate to the ability of soil to function effectively as a component of a healthy ecosystem (Costantini et al., 2015) Using soil quality indicators may be a valuable approach to assess functionality of topsoil and novel substrates used in restoration (Muñoz-Rojas et al., 2014; 2015). A key soil chemical indicator is soil organic C, that has been widely used as an attribute of soil quality because of the many functions that it provides and supports (Willaarts et al., 2015). However, microbial indicators can be more sensitive to disturbances and could be a valuable addition in soil assessment studies in restoration programs. Here, we propose a set of soil quality indicators to assess the soil status in restored soils (topsoil and waste material) of semi-arid environments. The study was conducted during March 2015 in the Pilbara biogeographical region (northwestern Australia) at an iron ore mine site rehabilitated in 2011. Methods Soil samples were collected from two sub-areas with different soil materials used as growth media: topsoil retrieved from nearby stockpiles and a lateritic waste material utilised for its erosive stability and physical competence. An undisturbed natural shrub-grassland ecosystem dominated by Triodia spp. and Acacia spp. representative of the restored area was selected as the analogue reference site. Soil physicochemical analysis were undertaken according to standard methods

  20. DETECTING LAND COVER CHANGE AT THE JORNADA EXPERIMENTAL RANGE, NEW MEXICO WITH ASTER EMISSIVITIES

    Science.gov (United States)

    Detecting land cover change over semi-arid rangeland is important for monitoring vegetation responses to drought, population expansion, and changing agricultural practices. Such change can be detected using vegetation indices, but these do not represent non-green vegetation and are dominated by seas...

  1. Carbon dioxide emissions from semi-arid soils amended with biochar alone or combined with mineral and organic fertilizers.

    Science.gov (United States)

    Fernández, José M; Nieto, M Aurora; López-de-Sá, Esther G; Gascó, Gabriel; Méndez, Ana; Plaza, César

    2014-06-01

    Semi-arid soils cover a significant area of Earth's land surface and typically contain large amounts of inorganic C. Determining the effects of biochar additions on CO2 emissions from semi-arid soils is therefore essential for evaluating the potential of biochar as a climate change mitigation strategy. Here, we measured the CO2 that evolved from semi-arid calcareous soils amended with biochar at rates of 0 and 20tha(-1) in a full factorial combination with three different fertilizers (mineral fertilizer, municipal solid waste compost, and sewage sludge) applied at four rates (equivalent to 0, 75, 150, and 225kg potentially available Nha(-1)) during 182 days of aerobic incubation. A double exponential model, which describes cumulative CO2 emissions from two active soil C compartments with different turnover rates (one relatively stable and the other more labile), was found to fit very well all the experimental datasets. In general, the organic fertilizers increased the size and decomposition rate of the stable and labile soil C pools. In contrast, biochar addition had no effects on any of the double exponential model parameters and did not interact with the effects ascribed to the type and rate of fertilizer. After 182 days of incubation, soil organic and microbial biomass C contents tended to increase with increasing the application rates of organic fertilizer, especially of compost, whereas increasing the rate of mineral fertilizer tended to suppress microbial biomass. Biochar was found to increase both organic and inorganic C contents in soil and not to interact with the effects of type and rate of fertilizer on C fractions. As a whole, our results suggest that the use of biochar as enhancer of semi-arid soils, either alone or combined with mineral and organic fertilizers, is unlikely to increase abiotic and biotic soil CO2 emissions.

  2. Application of Public-Private Partnership in Land Degradation Control and A Case Study

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The paper reviewed the background of public-private partnership (PPP) development, described PPP concept, characteristics and basic models, and analyzed the necessity and feasibility to develop land degradation control PPP. Then the experiences that Elion Resources Group in Inner Mongolia has accumulated in Kubuqi Desert control and development as well as the revelations were summarized with the hope to provide reference for establishing land degradation control PPP in arid area of western region.

  3. Urban Growth Detection Using Filtered Landsat Dense Time Trajectory in an Arid City

    Science.gov (United States)

    Ye, Z.; Schneider, A.

    2014-12-01

    Among all remote sensing environment monitoring techniques, time series analysis of biophysical index is drawing increasing attention. Although many of them studied forest disturbance and land cover change detection, few focused on urban growth mapping at medium spatial resolution. As Landsat archive becomes open accessible, methods using Landsat time-series imagery to detect urban growth is possible. It is found that a time trajectory from a newly developed urban area shows a dramatic drop of vegetation index. This enable the utilization of time trajectory analysis to distinguish impervious surface and crop land that has a different temporal biophysical pattern. Also, the time of change can be estimated, yet many challenges remain. Landsat data has lower temporal resolution, which may be worse when cloud-contaminated pixels and SLC-off effect exist. It is difficult to tease apart intra-annual, inter-annual, and land cover difference in a time series. Here, several methods of time trajectory analysis are utilized and compared to find a computationally efficient and accurate way on urban growth detection. A case study city, Ankara, Turkey is chosen for its arid climate and various landscape distributions. For preliminary research, Landsat TM and ETM+ scenes from 1998 to 2002 are chosen. NDVI, EVI, and SAVI are selected as research biophysical indices. The procedure starts with a seasonality filtering. Only areas with seasonality need to be filtered so as to decompose seasonality and extract overall trend. Harmonic transform, wavelet transform, and a pre-defined bell shape filter are used to estimate the overall trend in the time trajectory for each pixel. The point with significant drop in the trajectory is tagged as change point. After an urban change is detected, forward and backward checking is undertaken to make sure it is really new urban expansion other than short time crop fallow or forest disturbance. The method proposed here can capture most of the urban

  4. Living Lands

    DEFF Research Database (Denmark)

    Christensen, Suna Møller

    2014-01-01

    , hunters attended to questions like safe-journeying on ice or the role of natural surroundings in children’s education, in ways revealing a relational perception of ‘nature’ and dissolving culture-nature dualisms. Hunters’ experiences in living the land afforded children a dwelling position from which...... of the social world pushes questions about education and life, disregarding being educated as human control of nature....

  5. The experience of land cover change detection by satellite data

    Institute of Scientific and Technical Information of China (English)

    Lev SPIVAK; Irina VITKOVSKAYA; Madina BATYRBAYEVA; Alexey TEREKHOV

    2012-01-01

    Sigificant dependence from climate and anthropogenic influences characterize ecological systems of Kazakhstan.As result of the geographical location of the republic and ecological situation vegetative degradation sites exist throughout the territory of Kazakhstan.The major process of desertification takes place in the arid and semi-arid areas.To allocate spots of stable degradation of vegetation,the transition zone was first identified.Productivity of vegetation in transfer zone is slightly dependent on climate conditions.Multi-year digital maps of vegetation index were generated with NOAA satellite images.According to the result,the territory of the republic was zoned by means of vegetation productivity criterion.All the arable lands in Kazakhstan are in the risky agriculture zone.Estimation of the productivity of agricultural lands is highly important in the context of risky agriculture,where natural factors,such as wind and water erosion,can significantly change land quality in a relatively short time period.We used an integrated vegetation index to indicate land degradation measures to assess the inter-annual features in the response of vegetation to variations in climate conditions from lowresolution satellite data for all of Kazakhstan.This analysis allowed a better understanding of the spatial and temporal variations of land degradation in the country.

  6. Impacts of urbanization on nitrogen cycling and aerosol, surface and groundwater transport in semi-arid regions

    Science.gov (United States)

    Lohse, K. A.; Gallo, E.; Carlson, M.; Riha, K. M.; Brooks, P. D.; McIntosh, J. C.; Sorooshian, A.; Michalski, G. M.; Meixner, T.

    2011-12-01

    Semi-arid regions are experiencing disproportionate increases in human population and land transformation worldwide, taxing limited water resources and altering nitrogen (N) biogeochemistry. How the redistribution of water and N by urbanization affects semi-arid ecosystems and downstream water quality (e.g. drinking water) is unclear. Understanding these interactions and their feedbacks will be critical for developing science-based management strategies to sustain these limited resources. This is especially true in the US where some of the fastest growing urban areas are in semi-arid ecosystems, where N and water cycles are accelerated, and intimately coupled, and where runoff from urban ecosystems is actively managed to augment a limited water supply to the growing human population. Here we synthesize several ongoing studies from the Tucson Basin in Arizona and examine how increasing urban land cover is altering rainfall-runoff relationships, groundwater recharge, water quality, and long range transport of atmospheric N. Studies across 5 catchments varying in impervious land cover showed that only the least impervious catchment responded to antecedent moisture conditions while hydrologic responses were not statistically related to antecedent rainfall conditions at more impervious sites. Regression models indicated that rainfall depth, imperviousness, and their combined effect control discharge and runoff ratios (p < 0.01, r2 = 0.91 and 0.75, respectively). In contrast, runoff quality was not predictably related to imperviousness or catchment size. Rather, rainfall depth and duration, time since antecedent rainfall, and stream channel characteristics and infrastructure controlled runoff chemistry. Groundwater studies showed nonpoint source contamination of CFCs and associated nitrate in areas of rapid recharge along ephemeral channels. Aerosol measurements indicate that both long-range transport of N and N emissions from Tucson are being transported and deposited

  7. 极端干旱荒漠的“荒漠化”%Desertification of extra-arid deserts

    Institute of Scientific and Technical Information of China (English)

    慈龙骏

    2011-01-01

    The desertification of extra-arid deserts discussed in this paper refers to land degradation caused by global changes including various human activities. Extra-arid deserts comprise 36.9% of the total area of arid lands in China. Fifty percent of extra-arid deserts have some productivity, and they can most often be characterized as the terminal point of the biogeochemical cycle system in the desert basin. These areas are important because of their enormous potential for scientific research and creative discoveries, as well as new frontiers for development of the national economy. These areas are also of great importance in the fields of energy, mineral resources, water resources, biodiversity, tourism, local specialized agriculture and other aspects. With the current global crisis of decreasing fertile lands and increasing population, these large areas of marginal land with potential productivity need to be better understood and reevaluated. The natural environments in the region of extra-arid deserts are extremely low because of destructive sand-storms, land degradation, global changes and greater human interference. Additionally, there has been a series of major ecological andenvironmental events that have seriously affected extra-arid deserts. Continued desertification in the extra-arid deserts has a strong adverse effect on the national economy and society. Because of the current national economic boom and biogeographical and biogeochemical evidence, now is the right time to develop a concept for extra-arid deserts, as well as their management and conservation. A proposed classification and characteristics of the desertification of these deserts and technical measures for their conservation and restoration are presented here. The futures of extra-arid deserts will depend on acceptance of this concept by both academia and the government. Incorporating I) the combating of desertification of extra-arid deserts, and ii) the ecological restoration of the Northwest

  8. Actinobacteria from arid and desert habitats: diversity and biological activity

    Directory of Open Access Journals (Sweden)

    Joachim eWink

    2016-01-01

    Full Text Available Abstract The lack of new antibiotics in the pharmaceutical pipeline guides more and more researchers to leave the classical isolation procedures and to look in special niches and ecosystems. Bioprospecting of extremophilic Actinobacteria through mining untapped strains and avoiding resiolation of known biomolecules is among the most promising strategies for this purpose. With this approach, members of acidtolerant, alkalitolerant, psychrotolerant, thermotolerant, halotolerant and xerotolerant Actinobacteria have been obtained from respective habitats. Among these, little survey exists on the diversity of Actinobacteria in arid areas, which are often adapted to relatively high temperatures, salt concentrations, and radiation. Therefore, arid and desert habitats are special ecosystems which can be recruited for the isolation of uncommon Actinobacteria with new metabolic capability.At the time of this writing, members of Streptomyces, Micromonospora, Saccharothrix, Streptosporangium, Cellulomonas, Amycolatopsis, Geodermatophilus, Lechevalieria, Nocardia and Actinomadura are reported from arid habitats. However, metagenomic data present dominant members of the communities in desiccating condition of areas with limited water availability that are not yet isolated. Furthermore, significant diverse types of polyketide synthase (PKS and nonribosomal peptide synthetase (NRPS genes are detected in xerophilic and xerotolerant Actinobacteria and some bioactive compounds are reported from them. Rather than pharmaceutically active metabolites, molecules with protection activity against drying such as Ectoin and Hydroxyectoin with potential application in industry and agriculture have also been identified from xerophilic Actinobacteria. In addition, numerous biologically active small molecules are expected to be discovered from arid adapted Actinobacteria in the future. In the current survey, the diversity and biotechnological potential of Actinobacteria

  9. Global synthesis of groundwater recharge in semiarid and arid regions

    Science.gov (United States)

    Scanlon, B.R.; Keese, K.E.; Flint, A.L.; Flint, L.E.; Gaye, C.B.; Edmunds, W.M.; Simmers, I.

    2006-01-01

    Global synthesis of the findings from ???140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique is widely used to estimate recharge. Average recharge rates estimated over large areas (40-374000 km2) range from 0.2 to 35 mm year-1, representing 0.1-5% of long-term average annual precipitation. Extreme local variability in recharge, with rates up to ???720 m year-1, results from focussed recharge beneath ephemeral streams and lakes and preferential flow mostly in fractured systems. System response to climate variability and land use/land cover (LU/LC) changes is archived in unsaturated zone tracer profiles and in groundwater level fluctuations. Inter-annual climate variability related to El Nin??o Southern Oscillation (ENSO) results in up to three times higher recharge in regions within the SW US during periods of frequent El Nin??os (1977-1998) relative to periods dominated by La Nin??as (1941-1957). Enhanced recharge related to ENSO is also documented in Argentina. Climate variability at decadal to century scales recorded in chloride profiles in Africa results in recharge rates of 30 mm year-1 during the Sahel drought (1970-1986) to 150 mm year-1 during non-drought periods. Variations in climate at millennial scales in the SW US changed systems from recharge during the Pleistocene glacial period (??? 10 000 years ago) to discharge during the Holocene semiarid period. LU/LC changes such as deforestation in Australia increased recharge up to about 2 orders of magnitude. Changes from natural grassland and shrublands to dryland (rain-fed) agriculture altered systems from discharge (evapotranspiration, ET) to recharge in the SW US. The

  10. Global synthesis of groundwater recharge in semiarid and arid regions

    Science.gov (United States)

    Scanlon, Bridget R.; Keese, Kelley E.; Flint, Alan L.; Flint, Lorraine E.; Gaye, Cheikh B.; Edmunds, W. Michael; Simmers, Ian

    2006-10-01

    Global synthesis of the findings from 140 recharge study areas in semiarid and arid regions provides important information on recharge rates, controls, and processes, which are critical for sustainable water development. Water resource evaluation, dryland salinity assessment (Australia), and radioactive waste disposal (US) are among the primary goals of many of these recharge studies. The chloride mass balance (CMB) technique is widely used to estimate recharge. Average recharge rates estimated over large areas (40-374 000 km2) range from 0.2 to 35 mm year-1, representing 0.1-5% of long-term average annual precipitation. Extreme local variability in recharge, with rates up to 720 m year-1, results from focussed recharge beneath ephemeral streams and lakes and preferential flow mostly in fractured systems. System response to climate variability and land use/land cover (LU/LC) changes is archived in unsaturated zone tracer profiles and in groundwater level fluctuations. Inter-annual climate variability related to El Niño Southern Oscillation (ENSO) results in up to three times higher recharge in regions within the SW US during periods of frequent El Niños (1977-1998) relative to periods dominated by La Niñas (1941-1957). Enhanced recharge related to ENSO is also documented in Argentina. Climate variability at decadal to century scales recorded in chloride profiles in Africa results in recharge rates of 30 mm year-1 during the Sahel drought (1970-1986) to 150 mm year-1 during non-drought periods. Variations in climate at millennial scales in the SW US changed systems from recharge during the Pleistocene glacial period (10 000 years ago) to discharge during the Holocene semiarid period. LU/LC changes such as deforestation in Australia increased recharge up to about 2 orders of magnitude. Changes from natural grassland and shrublands to dryland (rain-fed) agriculture altered systems from discharge (evapotranspiration, ET) to recharge in the SW US. The impact of LU

  11. Restoration of surface-mined lands with rainfall harvesting

    Energy Technology Data Exchange (ETDEWEB)

    Sauer, R.H.; Rickard, W.H.

    1982-12-01

    Strip mining for coal in the arid western US will remove grazing land as energy demands are met. Conventional resotration usually includes leveling the spoil banks and covering them with top soil, fertilizing, seeding and irrigation with well or river water. An overview of research on an alternate method of restoring this land is reported. From 1976 through 1981 studies were conducted on the use of water harvesting, the collection and use of rainfall runoff, to restore the vegetative productivity of strip mined lands in arid regions. These studies tested the technical and economic feasibility of using partially leveled spoil banks at strip mines as catchment areas to collect and direct runoff to the topsoiled valley floor where crops were cultivated. Information was collected on the efficiency of seven treatments to increase runoff from the catchment areas and on the productivity of seven crops. The experiments were conducted in arid areas of Washington, Arizona, and Colorado. It was concluded that water harvesting can replace or augment expensive and inadequate supplies of well and river water in arid regions with a suitable climate. These studies showed that some treatments provided adequate runoff to produce a useful crop in the valleys, thus making this alternative approach to restoration technically feasible. This approach was also potentially economically feasible where the treatment costs of the catchment areas were low, the treatment was effective, the crop was productive and valuable, and earthmoving costs were lower than with conventional restoration involving complete leveling of spoil banks. It was also concluded that water harvesting can be made more effective with further information on catchment area treatments, which crops are most adaptable to water harvesting, the optimum incline of the catchment areas and climatic influences on water harvesting.

  12. Potential of arid zone vegetation as a source of substrates

    Energy Technology Data Exchange (ETDEWEB)

    Bassham, J.A.

    1977-11-01

    Three aspects of the potential of vegetation in arid zones as a source of substrates are discussed. The first includes the limitations on efficiency of conversion of solar energy to the stored chemical energy of biomass in green plants, and the subsequent biochemical pathways of carbon dioxide fixation and biosynthesis. Second is the potential of plants endogenous to arid zones. Finally, the use of covered agriculture or controlled environmental agriculture (CEA) is considered both in its present form and in terms of possible extenion to the large scale production of stable crops. (JGB)

  13. Mediterranean semi-arid systems-sensitivity and adaptation

    Energy Technology Data Exchange (ETDEWEB)

    Lavee, H.; Sarah, P.

    2009-07-01

    The semi-arid areas of the Mediterranean are sensitive to climate change as they are located. In many cases, between two different systems, the arid system and the Mediterranean sub-humid system. A number of quick response ecogeomorphological variables were monitored along a climatic transect in Israel, running from west to east, covering an annual rainfall range of 700-100mm. The relationships of climatic conditions-available water soil properties overland flow erosion, were investigates. Soil samples were taken from open areas between shrubs and overland flow was monitored in posts of 7, 14 and 21 m in length (3m width). (Author)

  14. Workshop on environmental changes of arid regions convenes in Inner Mongolia

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Hosted by the CAS Institute of Geology and Geophysics and the local government, the International Workshop on Environmental Changes and Sustainable Development in Arid and Semi-arid Regions was held recently in Alashan Left Banner, Inner Mongolia.

  15. Evaluation of an extreme-condition-inverse calibration remote sensing model for mapping energy balance fluxes in arid riparian areas

    Science.gov (United States)

    Hong, S.-H.; Hendrickx, J. M. H.; Kleissl, J.; Allen, R. G.; Bastiaanssen, W. G. M.; Scott, R. L.; Steinwand, A. L.

    2014-12-01

    Accurate information on the distribution of the surface energy balance components in arid riparian areas is needed for sustainable management of water resources as well as for a better understanding of water and heat exchange processes between the land surface and the atmosphere. Since the spatial and temporal distributions of these fluxes over large areas are difficult to determine from ground measurements alone, their prediction from remote sensing data is very attractive as it enables large area coverage and a high repetition rate. In this study the Surface Energy Balance Algorithm for Land (SEBAL) was used to estimate all the energy balance components in the arid riparian areas of the Middle Rio Grande Basin (New Mexico), San Pedro Basin (Arizona), and Owens Valley (California). We compare instantaneous and daily SEBAL fluxes derived from Landsat TM images to surface-based measurements with eddy covariance flux towers. This study presents evidence that SEBAL yields reliable estimates for actual evapotranspiration rates in riparian areas of the southwestern United States. The great strength of the SEBAL method is its internal calibration procedure that eliminates most of the bias in latent heat flux at the expense of increased bias in sensible heat flux.

  16. Evaluation of an extreme-condition-inverse calibration remote sensing model for mapping energy balance fluxes in arid riparian areas

    Directory of Open Access Journals (Sweden)

    S.-H. Hong

    2014-12-01

    Full Text Available Accurate information on the distribution of the surface energy balance components in arid riparian areas is needed for sustainable management of water resources as well as for a better understanding of water and heat exchange processes between the land surface and the atmosphere. Since the spatial and temporal distributions of these fluxes over large areas are difficult to determine from ground measurements alone, their prediction from remote sensing data is very attractive as it enables large area coverage and a high repetition rate. In this study the Surface Energy Balance Algorithm for Land (SEBAL was used to estimate all the energy balance components in the arid riparian areas of the Middle Rio Grande Basin (New Mexico, San Pedro Basin (Arizona, and Owens Valley (California. We compare instantaneous and daily SEBAL fluxes derived from Landsat TM images to surface-based measurements with eddy covariance flux towers. This study presents evidence that SEBAL yields reliable estimates for actual evapotranspiration rates in riparian areas of the southwestern United States. The great strength of the SEBAL method is its internal calibration procedure that eliminates most of the bias in latent heat flux at the expense of increased bias in sensible heat flux.

  17. Restoring the biological crust cover of soils across biomes in arid North America

    Science.gov (United States)

    Garcia-Pichel, Ferran; Antoninka, Anita; Bowker, Matthew; Giraldo Silva, Ana; Nelson, Corey; Velasco Ayuso, Sergio; Barger, Nichole; Belnap, Jayne; Reed, Sasha; Duniway, Michael

    2015-04-01

    Biological soil crust communities provide important ecosystem services to arid lands, particularly regarding soil fertility and stability against erosion. In North America, and in many other areas of the globe, increasingly intense human activities, ranging from cattle grazing to military training, have resulted in the significant deterioration of biological soil surface cover of soils. With the intent of attaining sustainable land use practices, we are conducting a 5-year, multi-institutional research effort to develop feasible soil crusts restoration strategies for US military lands. We are including field sites of varying climatic regions (warm and cold deserts, in the Chihuahuan Desert and in the Great Basin, respectively) and varying edaphic characteristics (sandy and silty soils in each). We have multiple aims. First, we aim to establishing effective "biocrust nurseries" that produce viable and pedigreed inoculum, as a supply center for biocrust restoration and for research and development. Second, we aim to develop optimal field application methods of biocrust inoculum in a series of field trials. Currently in our second year of research, we will be reporting on significant advances made on optimizing methodologies for the large-scale supply of inoculum based on a) pedigreed laboratory cultures that match the microbial community structure of the original sites, and b) "in soil" biomass enhancement, whereby small amounts of local crusts are nursed under greenhouse conditions to yield hundred-fold increases in biomass without altering significantly community structure. We will also report on field trials for methodologies in field application, which included shading, watering, application of chemical polymers, and soil surface roughening. In a soon-to-be-initiated effort we also aim to evaluate soil and plant responses to biocrust restoration with respect to plant community structure, soil fertility, and soil stability, in multi-factorial field experiments. An

  18. Developing a Land Suitability Index for Agricultural uses in Dry Lands from Geologic Point of View Using GIS - a Case Study from Jordan

    OpenAIRE

    Mohammmad Al Farajat; Alsharifa Hind Mohammad; Abdullah Diabat; Hassan Al Ibraheem

    2015-01-01

    DOI:10.17014/ijog.2.2.63-76In the context of the study, a Multi-criteria evaluation (MCE) in GIS was used in developing suitability index to optimize suitable lands for agricultural uses and seasonal farming in dry lands from geologic point of view. This study was performed in the areas between Mafraq and Zarqa Cities in Jordan which are classified as arid lands. The study aims at protecting groundwater from pollution, reducing soil salting, reducing irrigation water loss caused by evaporatio...

  19. Effects of environmental conditions on soil salinity and arid region in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Ben Ahmed, C.; Ben Rouina, B.; Boukhris, M.

    2009-07-01

    The shortage of water resources of good water quality is becoming an issue in the arid and semi arid regions. for this reason, the use of water resources of marginal quality such as treated wastewater and saline groundwater has become and important consideration, particularly in arid region in Tunisia, where large quantities of saline water are used for irrigation. (Author)

  20. Spectral unmixing model to assess land cover fractions in Mongolian steppe regions

    OpenAIRE

    Byambakhuu, Ishgaldan; Sugita, Michiaki; Matsushima, Dai

    2010-01-01

    The land cover fractions (LCFs) and spectral reflectance of photosynthetic vegetation (PV), nonphotosynthetic vegetation (NPV), and bare soil were measured at 58 sites in semi-arid and arid regions of Mongolia in the summers of 2005 and 2006. These data sets allowed a detailed assessment of the impact of measurement geometry as represented by the solar zenith angle θs, sensor view zenith angle θv and azimuth view angle phi in the estimation of LCF values by means of the spectral unmixing mo...

  1. Reflexive Water Management in Arid Regions: The Case of Iran

    NARCIS (Netherlands)

    Balali, M.R.; Keulartz, F.W.J.; Korthals, M.

    2009-01-01

    To illuminate the problems and perspectives of water management in Iran and comparable (semi-) arid Middle East and North Africa (MENA) countries, three paradigms can be distinguished: the traditional, the industrial and the reflexive paradigm. Each paradigm is characterised by its key technical sys

  2. Evaporation as the transport mechanism of metals in arid regions.

    Science.gov (United States)

    Lima, Ana T; Safar, Zeinab; Loch, J P Gustav

    2014-09-01

    Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust.

  3. Extreme climatic events shape arid and semiarid ecosystems

    NARCIS (Netherlands)

    Holmgren, M.; Stapp, P.; Dickman, C.; Gracia, C.; Graham, S.

    2006-01-01

    Climatic changes associated with the El Nino Southern Oscillation (ENSO) can have a dramatic impact on terrestrial ecosystems worldwide, but especially on arid and semiarid systems, where productivity is strongly limited by precipitation. Nearly two decades of research, including both short-term exp

  4. Trends and responses to global change of China's arid regions

    Institute of Scientific and Technical Information of China (English)

    Weixi YANG

    2009-01-01

    Ⅰ analyzed and elaborated the trends in and responses to global change in arid regions of China, from the perspective of nine variables, i.e., temperature, precipitation, river runoff, melting glaciers, water level of lakes, wind power and evaporation, vegetation, oases, and desertification. The climate and hydrology data Ⅰ citedrepresent many years of observations. Ⅰ conclude that, since the 1980s, the climate in arid regions of China has clearly changed with rising temperatures and precipitation in most areas. Wind power and the number of galestorm days have continuously decreased, which resulted in an improvement of humid conditions and increases in river discharge and water levels of lakes. Simultaneously, vegetation also has improved and the process of deserti-fication has essentially been arrested. Although there are some unfavorable developments, such as decreased river flows or flow interruptions and downstream oases have suffered from degradation, these incidental cases should not distract our attention from the generally favorable trends during the middle and late 20th century. These discordant phenomena are not consequences of climate change but rather of unsuitable human activities. Despitea substantial increase in precipitation, the level of the original precipitation was so small that any increase in precipitation was still small. As a result, none of the fundamental conditions such as a scarcity of water resources and precipitation nor the landscape of drought-ridden deserts in the arid regions will change. The vulnerability of the eco-environmental system in the arid regions will not change fundamentally either in the near future.

  5. Local facilitation, bistability and transitions in arid ecosystems

    NARCIS (Netherlands)

    Kéfi, S.; Rietkerk, M.G.; Baalen, M. van; Loreau, M.

    2007-01-01

    Arid ecosystems are liable to undergo sudden discontinuous transitions from a vegetated to a desert state as a result of human pressure and climate change. A predictive framework about the conditions under which such transitions occur is lacking. Here, we derive and analyze a general model describin

  6. Improved climate risk simulations for rice in arid environments

    NARCIS (Netherlands)

    Oort, van P.A.J.; Vries, de M.; Yoshida, H.; Saito, K.

    2015-01-01

    We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potenti

  7. On dew and micrometeorology in an arid coastal ecosystem

    NARCIS (Netherlands)

    Heusinkveld, B.G.

    2008-01-01

    This study investigated intriguing aspects of dew within a sandy arid ecosystem situated in the NW Negev desert, Israel. The goal was to quantify dew formation and evaporation processes through sensor design, field measurements and modelling. To do this, two new sensors were developed. The first sen

  8. Evaporation as the transport mechanism of metals in arid regions

    KAUST Repository

    Lima, Ana T.

    2014-09-01

    Soils of arid regions are exposed to drought and drastic temperature oscillations throughout the year. Transport mechanisms in these soils are therefore very different from the ones in temperate regions, where rain dictates the fate of most elements in soils. Due to the low rainfall and high evaporation rates in arid regions, groundwater quality is not threatened and all soil contamination issues tend to be overlooked. But if soil contamination happens, where do contaminants go? This study tests the hypothesis of upward metal movement in soils when evaporation is the main transport mechanism. Laboratory evaporation tests were carried out with heavy metal spiked Saudi soil, using circulation of air as the driving force (Fig. 1). Main results show that loamy soil retains heavy metals quite well while evaporation drives heavy metals to the surface of a sandy soil. Evaporation transports heavy metals upward in sandy soils of arid regions, making them accumulate at the soil surface. Sand being the dominating type of soil in arid regions, soils can then be a potential source of contaminated aerosols and atmospheric pollution - a transboundary problem. Some other repercussions for this problem are foreseen, such as the public ingestion or inhalation of dust. © 2014 Elsevier Ltd.

  9. Evidence of Arid to Semi-arid Climate Near Western Pacific Warm Pool During Sea-Level Lowstands: Caliche Surfaces in Late Cenozoic Carbonates of Nansha Islands, South China Sea

    Science.gov (United States)

    Gong, S.; Mii, H.; Horng, C.; Huang, F.; Chi, W.; Yui, T.; Torng, P.; Huang, S.; Wang, S.; Wu, J.; Yang, K.

    2003-12-01

    Whether the climate of tropical seas during glacial periods became cold and dry has been an open debate. Models by different authors proposed the tropical sea-surface temperature (SST) during the Last Glacial Maximum (LGM) to be about 2\\deg lower, or 5-6\\deg lower than present. The controversy partly arise from disparate reconstructions of temperature from stable oxygen isotope archives of marine sediments. In this paper, we provide field evidence of semi-arid or arid climate during late Cenozoic sea-level lowstands from an atoll located in central South China Sea near the Western Pacific Warm Pool (WPWP). Lower rainfall and higher evaporation associated with the dry conditions might have resulted in less meteoric water component in the surface sea-water, and this factor should be taken into considerations in deciphering temperature from isotopic records. Taiping Islet (Itu Aba), located at N10\\deg 23' and E114\\deg 22' is part of the Nansha (Spratly) Islands near the northwestern margin of the Western Pacific Warm Pool. Rock cores of a borehole at Taiping became accessible to the authors in the recent years. We identified at least four subaerial exposure surfaces (SES) in the late Cenozoic carbonates. Caliche deposits are recognized on each of the four surfaces on the basis of alveolar texture, micro-rhizolith, caliche glaebules and corroded limestone nodules in reddish matrix (terra-rossa). Caliche developed on limestones typically forms in semi-arid to arid areas with annual precipitation from about 500 to 1000mm, while the modern annual rainfall of Nansha Island is 1800-2100mm. The occurrence of the Nansha caliche suggests the climate was much drier than present during the sea-level lowstands represented by the four SES. During the sea-level falls, reduced surface area of South China Sea with continental shelves exposed might have resulted in less moistures in the atmosphere and therefore less precipitation and higher evaporation rates. As a result, the

  10. Land Retirement as a Habitat Restoration Tool

    Science.gov (United States)

    Singh, P. N.; Wallender, W. W.

    2007-12-01

    Use of intensive irrigation in arid and semi-arid areas usually leads to gradual salination of the soil leading to crop yield decline. The salination problem is mitigated by applying irrigation in excess of crop requirements, which leaches the excess salt load to the groundwater. Insufficient natural or man made drainage to dispose off this saline recharge to the groundwater leads to a gradual rise in the water table and eventual encroachment upon the root zone. This may ultimately make the land unfit for any economically productive activity. The abandoned land may even lead to desertification with adverse environmental consequences. In drainage basins with no surface outflow (sometimes called closed basins), land retirement has been proposed as a management tool to address this problem. Land retirement essentially entails intentionally discontinuing irrigation of selected farmlands with the expectation that the shallow water table beneath those lands should drop and the root zone salinity level should decrease. In the San Joaquin Valley of California, intensive irrigation in conjunction with a shallow underlying layer of clay, known as the Corcoran clay layer and absence of a drainage system caused the root zone to become highly saline and the shallow water table to rise. Land retirement would remove from production those farmlands contributing the poorest quality subsurface drain water. Based on numerical models results, it was expected that with land retirement of substantial irrigated lands with poor drainage characteristics, beneath which lies shallow groundwater with high salt load, the shallow water table beneath those lands should drop. A part of the retired lands could also be used for wildlife habitat. A potential negative side of the land retirement option that has to be considered is that in certain enabling evapotranspiration, soil and water table conditions, water will be drawn upwards and evaporated, leaving a deposit of salts on the surface and in

  11. Land Use and Land Cover - Montana Land Cover Framework 2013

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This statewide land cover theme is a baseline digital map of Montana's natural and human land cover. The baseline map is adapted from the Northwest ReGAP project...

  12. Plant communities of the Soutpansberg Arid Northern Bushveld

    Directory of Open Access Journals (Sweden)

    Theo H.C. Mostert

    2009-01-01

    Full Text Available The Soutpansberg Arid Northern Bushveld is one of eight major vegetation types (MVT described for the Soutpansberg-Blouberg region. The plant communities of this MVT are described in detail. Main ecological drivers of the vegetation structure and species composition of these communities are discussed and some conservation recommendations are made. Phytosociological data from a subset of 72 Braun-Blanquet sample plots collected in the Soutpansberg Arid Northern Bushveld were classified using Two-way Indicator Species Analysis (TWINSPAN and ordinated using a Detrended Correspondence Analysis (DECORANA. The resulting classification was further refined with table-sorting procedures based on the Braun-Blanquet floristic-sociological approach to vegetation classification using the computer software MEGATAB and JUICE. Eight plant communities were identified and described as Commiphora tenuipetiolata-Adansonia digitata short open woodland, Ledebouria ovatifolia-Commiphora mollis short bushland, Phyllanthus reticulatus-Acacia nigrescens short bushland, Tinnea rhodesiana-Combretum apiculatum short bushland, Dichrostachys cinerea subsp. africana-Spirostachys africana low thickets, Themeda triandra-Pterocarpus rotundifolius short closed grassland on steep basaltic slopes, Cyperus albostriatus-Syzygium cordatum sandveld wetlands, and Sesamothamnus lugardii-Catophractes alexandri tall sparse shrubland. These plant communities are event-driven ecosystems, predominantly infl uenced by frequent droughts, exposure to desiccation and unpredictable rainfall events. The complex topography of the Soutpansberg further contributes to the aridity of these ecosystems. The classifi cation and ordination analyses show similar groupings in the vegetation of the Soutpansberg Arid Mountain Bushveld. This confi rms the usefulness of complimentary analysis, using both classifi cation and ordination methods on a single data set in order to examine patterns and to search for

  13. Causes of early Holocene desertification in arid central Asia

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Liya [Lanzhou University, Key Laboratory of Western China' s Environmental System, Lanzhou, Gansu (China); University of Kiel, Institute of Geosciences, Kiel (Germany); Chen, Fahu [Lanzhou University, Key Laboratory of Western China' s Environmental System, Lanzhou, Gansu (China); Morrill, Carrie [University of Colorado, Cooperative Institute for Research in Environmental Sciences, Boulder, CO (United States); NOAA' s National Climatic Data Center, Paleoclimatology Branch, Boulder, CO (United States); Otto-Bliesner, Bette L.; Rosenbloom, Nan [National Center for Atmospheric Research, Climate and Global Dynamics Division, Boulder, CO (United States)

    2012-04-15

    Paleoclimate records of effective moisture (precipitation minus evaporation, or P-E) show a dry (low effective moisture) period in mid-latitude arid/semi-arid central Asia during the early Holocene (11,000-8,000 years ago) relative to the middle and late Holocene, in contrast to evidence for greater-than-present precipitation at the same time in the south and east Asian monsoonal areas. To investigate the spatial differences in climate response over mid-latitude central Asia and monsoonal Asia we conducted a series of simulations with the Community Climate System Model version 3 coupled climate model for the early, middle and late Holocene. The simulations test the climatic impact of all important forcings for the early Holocene, including changes in orbital parameters, the presence of the remnant Laurentide ice sheet and deglacial freshening of the North Atlantic. Model results clearly show the early Holocene patterns indicated by proxy records, including both the decreased effective moisture in arid central Asia, which occurs in the model primarily during the winter months, and the increase in summer monsoon precipitation in south and east Asia. The model results suggest that dry conditions in the early Holocene in central Asia are closely related to decreased water vapor advection due to reduced westerly wind speed and less evaporation upstream from the Mediterranean, Black, and Caspian Seas in boreal winter. As an extra forcing to the early Holocene climate system, the Laurentide ice sheet and meltwater fluxes have a substantial cooling effect over high latitudes, especially just over and downstream of the ice sheets, but contribute only to a small degree to the early Holocene aridity in central Asia. Instead, most of the effective moisture signal can be explained by orbital forcing decreasing the early Holocene latitudinal temperature gradient and wintertime surface temperature. We find little evidence for regional subsidence related to a stronger summer Asian

  14. Land management and development

    DEFF Research Database (Denmark)

    Enemark, Stig

    2006-01-01

    Land management is the process by which the resources of land are put into good effect. Land management encompasses all activities associated with the management of land that are required to achieve sustainable development. The concept of land includes properties and natural resources and thereby...... land related data. It is argued that development of such a model is important or even necessary for facilitating a holistic approach to the management of land as the key asset of any nation or jurisdiction....

  15. Atmospheric-Ecosystem CO2 Exchange in Sparse Arid Shrublands Across the Great Basin USA Over Multiple Years: Identifying Patterns and Mechanisms

    Science.gov (United States)

    Arnone, J. A.; Jasoni, R. L.; Larsen, J. D.; Fenstermaker, L. F.; Wohlfahrt, G.

    2008-12-01

    Up to recently, desert ecosystems have essentially been ignored with respect to their influence on global carbon cycling and their potential role in modulating atmospheric CO2 levels. Because deserts, defined here as ecosystems receiving Larrea tridentata)-dominated ecosystems, high desert sagebrush steppe (Aremesia tridentata) ecosystems, and greasewood (Sarcobatus vermiculatus) ecosystems have been largely positive (net C uptake by ecosystems; range of zero to 90 g C m-2 yr-1) and often large (as high 100 to 180 g C m-2 yr-1). Thus, the data from these arid shrublands suggest a much larger arid land C sink than has been previously assumed and call for closer tracking of the CO2 fluxes in these ecosystems.

  16. POTENTIAL OF INDUSTRIAL WASTE WATER USE FOR JATROPHA CULTIVATION IN ARID LAND

    Directory of Open Access Journals (Sweden)

    Hanaa Hussein Abd El Baky

    2013-01-01

    Full Text Available A pot experiment was conducted in the greenhouse of the National Research Center, Dokki, Cairo, Egypt to investigate the effect of NKP foliar fertilizer and irrigation by Industrial Drainage Water (IDW on Lipid Peroxidation (LP and antioxidant enzyme activities [Catalase (CAT, Suproxide Desmatase (SOD and Ascorbate Peroxidas (APX] of jatropha plants. Plants fertilized with NPK fertilizers (N0g+P0g+K0g, N3g+P3g+K3g and N6g+P6g+k6g/pot and irrigated by mixed varied levels of industrial drainage water (0, 25, 50 and 75% IDW. Data showed that concentration of LP increased as percentage of IDW increased up to 75% and tended to decrease with water contains zero IDW. A positive relationship was observed between the CAT, SOD and APX enzyme activities and the level of IDW in irrigation water. The maximum values of the three enzymes activities were obtained with application of NPK: 2:2:2 followed by application of NPK: 1:1:1 as compared with to the control. The highest lipid peroxidation were detected in leaves of non fertilized plants and irrigated by IDW, whereas the lowest values were detected in leaves of plants fertilized by NPK: 2:2:2 by fresh water.

  17. Hydrologic alteration affects aquatic plant assemblages in an arid-land river

    Science.gov (United States)

    Vinson, Mark; Hestmark, Bennett; Barkworth, Mary E.

    2014-01-01

    We evaluated the effects of long-term flow alteration on primary-producer assemblages. In 1962, Flaming Gorge Dam was constructed on the Green River. The Yampa River has remained an unregulated hydrologically variable river that joins the Green River 100 km downstream from Flaming Gorge Dam. In the 1960s before dam construction only sparse occurrences of two macroalgae, Cladophora and Chara, and no submerged vascular plants were recorded in the Green and Yampa rivers. In 2009–2010, aquatic plants were abundant and widespread in the Green River from the dam downstream to the confluence with the Yampa River. The assemblage consisted of six vascular species, Elodea canadensis, Myriophyllum sibiricum, Nasturtium officinale,Potamogeton crispus, Potamogeton pectinatus, and Ranunculus aquatilis, the macroalgae Chara and Cladophora, and the bryophyte, Amblystegium riparium. In the Green River downstream from the Yampa River, and in the Yampa River, only sparse patches of Chara and Cladophora growing in the splash zone on boulders were collected. We attribute the observed changes in the Green River to an increase in water transparency and a reduction in suspended and bed-load sediment and high flow disturbances. The lack of hydrophyte colonization downstream from the confluence with the Yampa River has implications for understanding tributary amelioration of dam effects and for designing more natural flow-regime schedules downstream from large dams.

  18. Survey on pigeon pea production systems, utilization and marketing in semi-arid lands of Kenya

    Directory of Open Access Journals (Sweden)

    Baudoin J.P.

    2001-01-01

    Full Text Available In order to assess the status of pigeonpea (Cajanus cajan (L. Millsp. production in Kenya, two surveys were carried out in Makueni and Mbeere Districts in areas representative of the main agro-ecological pigeonpea producing zone of the country : (Mid-altitude ASAL. Participatory Rural Appraisal (PRA approach was chosen as research method and was completed by household interviews based on a semi-structured questionnaire. The main points developed are the presentation of the different farming systems in which pigeonpea is considered as an important legume crop, the identification of the factors explaining pigeonpea production variations, the quantification of the use of improved varieties and improved production practices, and the analysis of the major patterns and trends in pigeonpea production, consumption and marketing.

  19. Ecological footprint analysis based on RS and GIS in arid land

    Institute of Scientific and Technical Information of China (English)

    CHANGBin; XIONGLiya

    2005-01-01

    Sustainable development has become a primary objective for many countries and regions throughout the world now. The ecological footprint (EF) is a kind of concise method of quantifiably measuring the natural capital consumption and it can reflect the goal of sustainability. In this paper, the concept, the theory and method of ecological footprint are introduced. On this basis, the study brings forward the method of ecological footprint and capacity prediction. The method is employed for the ecological footprint prediction combining consumption model with population model and the technique is adopted for the ecological capacity (EC) prediction uniting the Geographical Cellular Automata (Geo CA) and Geographic Information System (GIS). The above models and methods are employed to calculate EF and EC in 1995 and 2000 and predict them in 2005 in Hexi Corridor. The result shows that EF is continually increasing, and EC ascended in the anterior 5 years and will descend in the posterior 5 years. This suit of method is of the character of accuracy and speediness.

  20. Impacts of climate change on nutrient cycling in semi-arid and arid ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Belnap, J. [National Biological Survey, Moab, UT (United States)

    1995-09-01

    Effective precipitation is a major factor in determining nutrient pathways in different ecosystems. Soil flora and fauna play a critical role in nutrient cycles of all ecosystems. Temperature, timing, and amounts of precipitation affect population composition, activity levels, biomass, and recovery rates from disturbance. Changes in these variables can result in very different inputs and outputs for different nutrients. As a result, areas with less effective precipitation have very different nutrient cycles than more mesic zones. Climate change, therefore, can profoundly affect the nutrient cycles of ecosystems. Nitrogen cycles may be especially sensitive to changes in temperature and to timing and amounts of precipitation. Rainfall contains varying amounts of nitrogen compounds. Changes in amounts of rainfall will change amounts of nitrogen available to these systems. Because rainfall is limited in semi-arid and regions, these systems tend to be more dependent on microbial populations for nitrogen input. Consequently, understanding the effects of climate change on these organisms is critical in understanding the overall effect on ecosystems.

  1. Digital Mapping of Soil Properties Using Multivariate Statistical Analysis and ASTER Data in an Arid Region

    Directory of Open Access Journals (Sweden)

    Said Nawar

    2015-01-01

    Full Text Available Modeling and mapping of soil properties has been identified as key for effective land degradation management and mitigation. The ability to model and map soil properties at sufficient accuracy for a large agriculture area is demonstrated using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER imagery. Soil samples were collected in the El-Tina Plain, Sinai, Egypt, concurrently with the acquisition of ASTER imagery, and measured for soil electrical conductivity (ECe, clay content and soil organic matter (OM. An ASTER image covering the study area was preprocessed, and two predictive models, multivariate adaptive regression splines (MARS and the partial least squares regression (PLSR, were constructed based on the ASTER spectra. For all three soil properties, the results of MARS models were better than those of the respective PLSR models, with cross-validation estimated R2 of 0.85 and 0.80 for ECe, 0.94 and 0.90 for clay content and 0.79 and 0.73 for OM. Independent validation of ECe, clay content and OM maps with 32 soil samples showed the better performance of the MARS models, with R2 = 0.81, 0.89 and 0.73, respectively, compared to R2 = 0.78, 0.87 and 0.71 for the PLSR models. The results indicated that MARS is a more suitable and superior modeling technique than PLSR for the estimation and mapping of soil salinity (ECe, clay content and OM. The method developed in this paper was found to be reliable and accurate for digital soil mapping in arid and semi-arid environments.

  2. Sediment delivery ratio in a small semi-arid watershed under conditions of low connectivity

    Directory of Open Access Journals (Sweden)

    Julio Cesar Neves dos Santos

    Full Text Available ABSTRACT The semi-arid region in the northeast of Brazil is characterised by rains of high intensity and short duration, with the processes of erosion being aggravated by an inappropriate land-use model. In this region, the lack of measured data for runoff and sediment yield increases the need to apply hydro-sedimentological models in estimating erosion, requiring knowledge of the actual sediment delivery ratio for the region. The aim of this study therefore, was to map soil erosion, making use of the Universal Soil Loss Equation (USLE, in the Iguatu Experimental Watershed (IEW. The mean annual sediment delivery ratio (SDR, and the SDR for individual events, was calculated from hydro-sedimentological measurements, contributing to an understanding of the processes of sediment propagation in the Brazilian semi-arid region, allowing identification of areas susceptible to water erosion. The IEW has an area of 16.74 km2 and is equipped with sensors for the continuous measurement of rainfall, flow and sediment yield. The mean annual SDR for the IEW was 0.37%. The SDR for individual rainfall events ranged from 0.08 to 1.67%, with an average of 0.68%. Among the main variables that influence the SDR for individual events is the magnitude of rainfall depth and antecedent soil moisture that can be better represented by the total antecedent precipitation of the previous 15 days. According to maps of soil loss, only 6.27% of the watershed presented losses beyond tolerable limits.

  3. Spatiotemporal soil and saprolite moisture dynamics across a semi-arid woody plant gradient

    Science.gov (United States)

    Niemeyer, Ryan J.; Heinse, Robert; Link, Timothy E.; Seyfried, Mark S.; Klos, P. Zion; Williams, Christopher J.; Nielson, Travis

    2017-01-01

    Woody plant cover has increased 10-fold over the last 140+ years in many parts of the semi-arid western USA. Woody plant cover can alter the timing and amount of plant available moisture in the soil and saprolite. To assess spatiotemporal subsurface moisture dynamics over two water years in a snow-dominated western juniper stand we compared moisture dynamics horizontally across a discontinuous canopy, and vertically in soil and saprolite. We monitored soil moisture at 15 and 60 cm and conducted periodic electromagnetic induction and electrical resistivity tomography surveys aimed at sensing moisture changes within the root zone and saprolite. Timing of soil moisture dry down at 15 cm was very similar between canopy patches and interspace. Conversely, dry down at 60 cm occurred 22 days earlier in the interspace than under canopy patches. After rainfall, interspaces with more shrubs showed greater increases in soil moisture than interspaces with few shrubs. For the few rainfall events that were large enough to increase soil moisture at 60 cm, increases in moisture occurred almost exclusively below the canopy. Soil water holding capacity from 0 to 150 cm was a primary driver of areas that were associated with the greatest change in distributed electrical conductivity - an indicator of changes in soil moisture - across the growing season. Vegetation was also correlated with a greater seasonal change in electrical conductivity at these depths. The seasonal change in resistivity suggested moisture extraction by juniper well into the saprolite, as deep as 12 m below the surface. This change in deep subsurface resistivity primarily occurred below medium and large juniper trees. This study suggests how tree roots are both increasing infiltration below their canopy while also extracting moisture at depths of upwards of 12 m. Information from this study can help improve our understanding of juniper resilience to drought and the hydrologic impacts of semi-arid land cover

  4. Spatial pattern of nitrogen isotopes as an indicator of ecosystem responses to rainfall in semi-arid and arid grasslands

    Science.gov (United States)

    WANG, C.; Bai, E.; Liu, D.; Fang, T. Y.; Jiang, P.; Han, G. X.

    2013-12-01

    Nitrogen (N) is an essential element for plant growth, however, whether it is a limiting factor of plant growth in water-limited areas is still not clear. Here we examined spatial variations of plant and soil stable N isotopes along a 3200 km precipitation gradient and proposed a conceptual model to explain ecosystem responses to increasing precipitation in arid and semi-arid grasslands in China. Soil δ15N increased with increasing MAP in areas with MAP areas with 200 mm 200 mm. In areas with MAP nutrient cycling in arid and semi-arid areas. If future climate change leads to drier climate in dryland, the uncoupled plant and microbial response may cause more N losses and higher ecosystem vulnerability. 3 Soil organic carbon (Soil C, a), total nitrogen (Soil N, b), C/N (c) and δ15N (d) of study sites along a MAP gradient. Relationship between MAP and foliar δ15N (a) and root δ15N (b).

  5. Validation of humidex in evaluating heat stress in the outdoor jobs in arid and semi-arid climates of Iran

    Directory of Open Access Journals (Sweden)

    Hamid Reza Heidari

    2016-09-01

    Full Text Available Introduction: Regarding development of several thermal indices and limitations of each, in this research applicability and validity of temperature- humidity index (Humidex were examined against the standard heat index, Wet Bulb Globe Temperature -WBGT, as well as tympanic temperature of subjects. Material and Method:  This cross-sectional study was done on 163 subjects at spring and summer (2013 in outdoor jobs of arid and semi-arid climates of Iran. Environmental parameters as well as tympanic temperature of subjects were measured simultaneously and then heat indices were determined. Data were analyzed using linear correlation charts and Kappa coefficient of agreement by means of SPSS software version 20. Results: A strong correlation was obtained between WBGT and Humidex in both arid and semi-arid regions (r>0.98, while the correlation between Humidex and tympanic temperature was moderate (r=0.5-0.8. Based on the obtained Kappa value, the agreement coefficient between Humidex and WBGT was 0.878. This value was obtained equal to 0.226 for the Humidex and tympanic temperature. Conclusion: The results of this study showed that Humidex can be applied as an appropriate substitute for the WBGT index. However, if evaluation of environmental condition with low air temperature or very hot situation is considered, relying only on the Humidex results will not provide a realistic estimation of thermal strain imposed to individuals.

  6. Satellite-based analysis of recent trends in the ecohydrology of a semi-arid region

    Directory of Open Access Journals (Sweden)

    M. Gokmen

    2013-10-01

    Full Text Available We present a regional framework for an integrated and spatiotemporally distributed assessment of human-induced trends in the hydrology and the associated ecological health of a semi-arid basin where both human activities (i.e. agriculture and natural ecosystems are highly groundwater dependent. To achieve this, we analysed the recent trends (from year 2000 to 2010 in precipitation, evapotranspiration (actual and potential and vegetation greenness (i.e. NDVI using a combination of satellite and ground-based observations. The trend assessment was applied for the semi-arid Konya Basin (Turkey, one of the largest endorheic basins in the world. The results revealed a consistent increasing trend of both yearly evapotranspiration (totally 63 MCM yr−1 from croplands and mean NDVI (about 0.004 NDVI yr−1 in irrigated croplands, especially concentrating in the plain part of the basin, while no significant trends were observed for the precipitation and potential evapotranspiration variables. On the contrary, a consistent decreasing trend of both yearly evapotranspiration (totally −2.1 MCM yr−1 and mean NDVI (−0.001 NDVI yr−1 was observed in the wetlands, which also cannot be explained by trends in precipitation and potential evapotranspiration. The emerging picture suggest that the greening trend of the vegetation and increasing of evapotranspiration in the plain are related to land cover changes (i.e. conversion into irrigated croplands and to the intensification of the supplementary irrigation for agriculture, which in turn caused drying out of some wetlands and the natural vegetation which mostly depend on the groundwater, the main source of irrigation water as well. Our study presented an example of the utility of spatially and temporally continuous RS data in assessing the regional trends in hydrological and ecological variables and their interactions in a spatially distributed manner in a semi-arid region, which can also be adapted to

  7. Drought, change and resilience in South Africa’s arid and semi-arid rangelands

    Directory of Open Access Journals (Sweden)

    Susanne Vetter

    2009-12-01

    Full Text Available Droughts can have serious ecological and economic consequences and will pose an increasing challenge to rangeland users as the global climate is changing. Finding ways to reduce ecological and economic impacts of drought should thus be a major research thrust. Resilience, defined as the amount of perturbation a social or ecological system can absorb without shifting to a qualitatively different state, has emerged as a prominent concept in ecosystem ecology and more recently as a conceptual framework for understanding and managing complex social-ecological systems. This paper discusses the application and relevance of resilience to understanding and managing ecosystem change, and enhancing the capacity of land users to adapt to droughts. Drought can trigger vegetation change and factors such as grazing management can influence the likelihood of such transitions. Drought can cause differential mortality of perennial plants and this could provide an opportunity for rangeland restoration by opening up establishment sites for desirable species. The capacity of land users to cope with drought is influenced by the resilience of their agro-ecosystems, the diversity of livelihood options, access to resources and institutional support. By these criteria, current agricultural development approaches in South Africa, particularly in communal rangelands and areas of land reform, are unlikely to enhance land users’ resilience to drought and other perturbations.

  8. Phosphorus transformations along a large-scale climosequence in arid and semiarid grasslands of northern China

    Science.gov (United States)

    Feng, Jiao; Turner, Benjamin L.; Lü, Xiaotao; Chen, Zhenhua; Wei, Kai; Tian, Jihui; Wang, Chao; Luo, Wentao; Chen, Lijun

    2016-09-01

    The Walker and Syers model of phosphorus (P) transformations during long-term soil development has been verified along many chronosequences but has rarely been examined along climosequences, particularly in arid regions. We hypothesized that decreasing aridity would have similar effects on soil P transformations as time by increasing the rate of pedogenesis. To assess this, we examined P fractions in arid and semiarid grassland soils (0-10 cm) along a 3700 km aridity gradient in northern China (aridity between 0.43 and 0.97, calculated as 1 - [mean annual precipitation/potential evapotranspiration]). Primary mineral P declined as aridity decreased, although it still accounted for about 30% of the total P in the wettest sites. In contrast, the proportions of organic and occluded P increased as aridity decreased. These changes in soil P composition occurred in parallel with marked shifts in soil nutrient stoichiometry, with organic carbon:organic P and nitrogen:organic P ratios increasing with decreasing aridity. These results indicate increasing abundance of P relative to carbon or nitrogen along the climosequence. Overall, our results indicate a broad shift from abiotic to biotic control on P cycling at an aridity value of approximately 0.7 (corresponding to about 250 mm mean annual rainfall). We conclude that the Walker and Syers model can be extended to climosequences in arid and semiarid ecosystems and that the apparent decoupling of nutrient cycles in arid soils is a consequence of their pedogenic immaturity.

  9. Genomic and proteomic characterization of ARID1A chromatin remodeller in ampullary tumors

    Science.gov (United States)

    Nastase, Anca; Teo, Jin Yao; Heng, Hong Lee; Ng, Cedric Chuan Young; Myint, Swe Swe; Rajasegaran, Vikneswari; Loh, Jia Liang; Lee, Ser Yee; Ooi, London Lucien; Chung, Alexander Yaw Fui; Chow, Pierce Kah Hoe; Cheow, Peng Chung; Wan, Wei Keat; Azhar, Rafy; Khoo, Avery; Xiu, Sam Xin; Alkaff, Syed Muhammad Fahmy; Cutcutache, Ioana; Lim, Jing Quan; Ong, Choon Kiat; Herlea, Vlad; Dima, Simona; Duda, Dan G; Teh, Bin Tean; Popescu, Irinel; Lim, Tony Kiat Hon

    2017-01-01

    AT rich interactive domain 1A (ARID1A) is one of the most commonly mutated genes in a broad variety of tumors. The mechanisms that involve ARID1A in ampullary cancer progression remains elusive. Here, we evaluated the frequency of ARID1A and KRAS mutations in ampullary adenomas and adenocarcinomas and in duodenal adenocarcinomas from two cohorts of patients from Singapore and Romania, correlated with clinical and pathological tumor features, and assessed the functional role of ARID1A. In the ampullary adenocarcinomas, the frequency of KRAS and ARID1A mutations was 34.7% and 8.2% respectively, with a loss or reduction of ARID1A protein in 17.2% of the cases. ARID1A mutational status was significantly correlated with ARID1A protein expression level (P=0.023). There was a significant difference in frequency of ARID1A mutation between Romania and Singapore (2.7% versus 25%, P=0.04), suggestive of different etiologies. One somatic mutation was detected in the ampullary adenoma group. In vitro studies indicated the tumor suppressive role of ARID1A. Our results warrant further investigation of this chromatin remodeller as a potential early biomarker of the disease, as well as identification of therapeutic targets in ARID1A mutated ampullary cancers.

  10. Integrated Land Management

    DEFF Research Database (Denmark)

    Enemark, Stig

    2004-01-01

    This paper aims to build a general understanding and conceptual approach to integrated land management. The conceptual understanding may take the form of a hierarchy of levels. The foundation stone is an overall national land policy. Appropriate cadastral systems support land policies by providing...... for integrated land management includes some educational and professional challenges to be met at the threshold of the third millennium.    In short, it is critical that we prepare the profession as well the educational system to meet the challenges of tomorrow in achieving sustainable urban and rural...... identification of the land parcels and a framework for security of tenure, land value and land use. Appropriate cadastral systems support a wider land administration infrastructure within the areas of land tenure, land value and land use. Appropriate land administration systems then form the basic for sound land...

  11. Modeling the Surface Water-Groundwater Interaction in Arid and Semi-Arid Regions Impacted by Agricultural Activities

    Science.gov (United States)

    Tian, Y.; Wu, B.; Zheng, Y.

    2013-12-01

    In many semi-arid and arid regions, interaction between surface water and groundwater plays an important role in the eco-hydrological system. The interaction is often complicated by agricultural activities such as surface water diversion, groundwater pumping, and irrigation. In existing surface water-groundwater integrated models, simulation of the interaction is often simplified, which could introduce significant simulation uncertainty under certain circumstance. In this study, GSFLOW, a USGS model coupling PRMS and MODFLOW, was improved to better characterize the surface water-groundwater interaction. The practices of water diversion from rivers, groundwater pumping and irrigation are explicitly simulated. In addition, the original kinematic wave routing method was replaced by a dynamic wave routing method. The improved model was then applied in Zhangye Basin (the midstream part of Heihe River Baisn), China, where the famous 'Silk Road' came through. It is a typical semi-arid region of the western China, with extensive agriculture in its oasis. The model was established and calibrated using the data in 2000-2008. A series of numerical experiments were conducted to evaluate the effect of those improvements. It has been demonstrated that with the improvements, the observed streamflow and groundwater level were better reproduced by the model. The improvements have a significant impact on the simulation of multiple fluxes associated with the interaction, such as groundwater discharge, riverbed seepage, infiltration, etc. Human activities were proved to be key elements of the water cycle in the study area. The study results have important implications to the water resources modeling and management in semi-arid and arid basins.

  12. Performance of Jatropha curcas L. in Semi-arid Zone: Seed Germination, Seedling Growth and Early Field Growth

    Directory of Open Access Journals (Sweden)

    Sharif AHAMAD

    2013-05-01

    Full Text Available There is a lack of information on basic agronomic properties of Jatropha curcas L. (jatropha cultivation on the marginal lands in the semi-arids. Evaluation of agronomic performance of identified elite strains of J. curcas in marginal lands would be of paramount importance for addressing gap areas in their agronomic properties and subsequently for harnessing their optimum economic potentials. The present study undertook the task of analysing the growth performance of a high oil bearing elite strain of J. curcas–DARL-2 in degraded land in semi-arid zone of Deccan Plateau, India. While undertaking the assessment of growth performance of elite strain DARL-2, two other native (wild strains (namely AHN-1 and AHN-2 of J. curcas were also considered so that a comparative evaluation could be carried out. The role of gypsum was also investigated on J. curcas in the nursery stage as well its carry over effects on growth performance of transplanted trees in the field. Two types of substrates, gypsum-treated soil (GS and untreated soil (SL were used for growing seedlings of all the three jatropha strains. Seedlings (120-days-old of DARL-2 exhibited greater plant height, collar diameter and number of branches but root length was greater in the local strains. In the second year of field transplantation, DARL-2 strain exhibited significantly (p<0.05 greater plant height and number of branches/plant. No carry over effects of gypsum treatment were observed in field transplanted plants as none of the growth parameters significantly varied among the substrate types.

  13. Land, kennis, moed en eenheid: conflicterende discoursen binnen samenleving en gezin over landbouw en droogte in Noordoost Brazilië

    NARCIS (Netherlands)

    Peerboom, I.B.F.C.

    2012-01-01

    This dissertation examines the survival strategies of family farmers in Conceição do Coité, Bahia, in semi-arid Brazil in 1997 and 2008 by using the livelihood framework. It analyses natural capital (land), human capital (work ethic and knowledge), and social capital (mutual aid). Greater access to

  14. Climate Warming Threatens Semi-arid Forests in Inner Asia

    Science.gov (United States)

    WU, X.; Liu, H.; Qi, Z.; Li, X.

    2014-12-01

    A line of evidences reveal an increasing tree growth decline and tree mortality mainly attributable to climate warming and the warming-mediated changes in drought and other processes (such as fire and insect dynamics) in many parts of world tropical, temperate and boreal forests. However, the growth responses to climate change of the widely distributed semi-arid forests are unclear. Here, we synthetically investigate the tree growth patterns during past decades and its interannual response to climate variations in Inner Asia combining the ground truth field survey and samplings, remote sensing observations and climate data. We identified a pervasive tree growth decline since mid-1990s in semi-arid forests in Inner Asia. The widely observed tree growth decline is dominantly attributable to warming-induced water stress during pre- and early growing season. Tree growth of semi-arid forests in Inner Asia is particularly susceptible to spring warming and has been suffering a prolonged growth limitation in recent decades due to spring warming-mediated water conditions. Additionally, we identified a much slower growth rate in younger trees and a lack of tree regeneration in these semi-arid forests. The widely observed forest growth reduction and lack of tree regeneration over semi-arid forests in Inner Asia could predictably exert great effects on forest structure, regionally/globally biophysical and biochemical processes and the feedbacks between biosphere and atmosphere. Notably, further increases in forest stress and tree mortality could be reasonably expected, especially in context of the increase frequency and severity of high temperature and heat waves and changes in forest disturbances, potentially driving the eventual regional loss of current semi-arid forests. Given the potential risks of climate induced forest dieback, increased management attention to adaptation options for enhancing forest resistance and resilience to projected climate stress can be expected

  15. Climate warming threatens semi-arid forests in Inner Asia

    Science.gov (United States)

    WU, X.

    2015-12-01

    A line of evidences reveal an increasing tree growth decline and tree mortality mainly attributable to climate warming and the warming-mediated changes in drought and other processes in many parts of world tropical, temperate and boreal forests. However, the growth responses to climate change of the widely distributed semi-arid forests are unclear. Here, we synthetically investigate the tree growth patterns during past decades and its interannual response to climate variations in Inner Asia combining the ground truth field survey and samplings, remote sensing observations and climate data. We identified a pervasive tree growth decline since mid-1990s in semi-arid forests in Inner Asia. The widely observed tree growth decline is dominantly attributable to warming-induced water stress during pre- and early growing season. Tree growth of semi-arid forests in Inner Asia is particularly susceptible to spring warming and has been suffering a prolonged growth limitation in recent decades due to spring warming-mediated water conditions. Additionally, we identified a much slower growth rate in younger trees and a lack of tree regeneration in these semi-arid forests. The widely observed forest growth reduction and lack of tree regeneration over semi-arid forests in Inner Asia could predictably exert great effects on forest structure, regionally/globally biophysical and biochemical processes and the feedbacks between biosphere and atmosphere. Notably, further increases in forest stress and tree mortality could be reasonably expected, especially in context of the increase frequency and severity of high temperature and heat waves and changes in forest disturbances, potentially driving the eventual regional loss of current semi-arid forests. Given the potential risks of climate induced forest dieback, increased management attention to adaptation options for enhancing forest resistance and resilience to projected climate stress can be expected. However, the functionally realistic

  16. Oasis dynamics change and its influence on landscape pattern on Jinta oasis in arid China from 1963a to 2010a: Integration of multi-source satellite images

    Science.gov (United States)

    Xie, Yuchu; Gong, Jie; Sun, Peng; Gou, Xiaohua

    2014-12-01

    As one of the vital research highlights of global land use and cover change, oasis change and its interaction with landscape pattern have been regarded as an important content of regional environmental change research in arid areas. Jinta oasis, a typical agricultural oasis characterized by its dramatic exploitation and use of water and land resources in Hexi corridor, northwest arid region in China, was selected as a case to study the spatiotemporal oasis change and its effects on oasis landscape pattern. Based on integration of Keyhole satellite photographs, KATE-200 photographs, Landsat MSS, TM and ETM+ images, we evaluated and analyzed the status, trend and spatial pattern change of Jinta oasis and the characteristics of landscape pattern change by a set of mathematical models and combined this information with landscape metrics and community surveys. During the period of 1963a-2010a, Jinta oasis expanded gradually with an area increase of 219.15 km2, and the conversion between oasis and desert was frequent with a state of “imbalance-balance-extreme imbalance conditions”. Moreover, most of the changes took place in the ecotone between oasis and desert and the interior of oasis due to the reclamation of abandoned land, such as Yangjingziwan and Xiba townships. Furthermore, the area, size and spatial distribution of oasis were influenced by human activities and resulted in fundamental changes of oasis landscape pattern. The fractal characteristics, dispersion degree and fragmentation of Jinta oasis decreased and the oasis landscape tended to be simple and uniform. Oasis change trajectories and its landscape pattern were mainly influenced by water resource utilization, policies (especially land policies), demographic factors, technological advancements, as well as regional economic development. We found that time series analysis of multi-source remote sensing images and the application of an oasis change model provided a useful approach to monitor oasis change

  17. Land Cover - Minnesota Land Cover Classification System

    Data.gov (United States)

    Minnesota Department of Natural Resources — Land cover data set based on the Minnesota Land Cover Classification System (MLCCS) coding scheme. This data was produced using a combination of aerial photograph...

  18. Land Competition and Land-Use Change:

    DEFF Research Database (Denmark)

    Vongvisouk, Thoumthone

    Land competition and land-use changes are taking place in many developing countries as the demand for land increases. These changes are leading to changes in the livelihood conditions of rural people. The Government of Laos (GoL), on the one hand, aims to increase forest protection. On the other...... hand, the government is also working to increase national economic growth by promoting private-sector investment in both agriculture and forest resources – two sectors that compete for the same areas intended for protection. This thesis explores how these contradictory drivers of land-use changes...... are affecting livelihoods in northern Laos. The research engages a range of approaches, theories and concepts, including political ecology, polycentric resource governance, land-change science, regime shifts in land systems, land sparing versus land sharing, and the sustainable livelihood framework. During...

  19. Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California.

    Science.gov (United States)

    Kim, Christopher S; Stack, David H; Rytuba, James J

    2012-07-01

    As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash.

  20. Dynamics of Soil Erosion as Influenced by Watershed Management Practices: A Case Study of the Agula Watershed in the Semi-Arid Highlands of Northern Ethiopia

    Science.gov (United States)

    Fenta, Ayele Almaw; Yasuda, Hiroshi; Shimizu, Katsuyuki; Haregeweyn, Nigussie; Negussie, Aklilu

    2016-11-01

    Since the past two decades, watershed management practices such as construction of stone bunds and establishment of exclosures have been widely implemented in the semi-arid highlands of northern Ethiopia to curb land degradation by soil erosion. This study assessed changes in soil erosion for the years 1990, 2000 and 2012 as a result of such watershed management practices in Agula watershed using the Revised Universal Soil Loss Equation. The Revised Universal Soil Loss Equation factors were computed in a geographic information system for 30 × 30 m raster layers using spatial data obtained from different sources. The results revealed significant reduction in soil loss rates by about 55 % from about 28 to 12 t ha-1 per year in 1990-2000 and an overall 64 % reduction from 28 to 10 t ha-1 per year in 1990-2012. This change in soil loss is attributed to improvement in surface cover and stone bund practices, which resulted in the decrease in mean C and P-factors, respectively, by about 19 % and 34 % in 1990-2000 and an overall decrease in C-factor by 29 % in 1990-2012. Considerable reductions in soil loss were observed from bare land (89 %), followed by cultivated land (56 %) and shrub land (49 %). Furthermore, the reduction in soil loss was more pronounced in steeper slopes where very steep slope and steep slope classes experienced over 70 % reduction. Validation of soil erosion estimations using field observed points showed an overall accuracy of 69 %, which is fairly satisfactory. This study demonstrated the potential of watershed management efforts to bring remarkable restoration of degraded semi-arid lands that could serve as a basis for sustainable planning of future developments of areas experiencing severe land degradation due to water erosion.

  1. Capo Verde, Land Use Land Cover

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This series of three-period land use land cover (LULC) datasets (1975, 2000, and 2013) aids in monitoring change in West Africa’s land resources (exception is...

  2. On coordinated development of oasis and environment in arid area

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based upon the formation and evolution of oasis and the factors restricting the coordinated development of oasis economy and environment, this paper presents a goal of the development in coordination. It suggests that the sustainable survival and development of oasis could be ensured only if the oasis-desert and water source ecology are managed in a combined way to form a macro system. In light with the above mentioned, the approach to the development of economy and environment of oasis in arid area should depend upon the establishment of an oasis ecological and economic system, which suits the arid environment and promotes the efficiency of resource configuration, stabilizes economic increment and benefits ecological development.

  3. Effectiveness of conservation agriculture practices on soil erosion processes in semi-arid areas of Zimbabwe

    Science.gov (United States)

    Chikwari, Emmanuel; Mhaka, Luke; Gwandu, Tariro; Chipangura, Tafadzwa; Misi Manyanga, Amos; Sabastian Matsenyengwa, Nyasha; Rabesiranana, Naivo; Mabit, Lionel

    2016-04-01

    - The application of fallout radionuclides (FRNs) in soil erosion and redistribution studies has gained popularity since the late 1980s. In Zimbabwe, soil erosion research was mostly based on conventional methods which included the use of erosion plots for quantitative measurements and erosion models for predicting soil losses. Only limited investigation to explore the possibility of using Caesium-137 (Cs-137) has been reported in the early 1990s for undisturbed and cultivated lands in Zimbabwe. In this study, the Cs-137 technique was applied to assess the impact of soil conservation practices on soil losses and to develop strategies and support effective policies that help farmers in Zimbabwe for sustainable land management. The study was carried out at the Makoholi research station 30 km north of the Masvingo region which is located 260 km south of Harare. The area is semi-arid and the study site comprises coarse loamy sands, gleyic lixisols. The conservation agriculture (CA) practices used within the area since 1988 include (i) direct seeding (DS) with mulch, (ii) CA basins with mulch, and (iii) 18 years direct seeding, left fallow for seven years and turned into conventional tillage since 2012 (DS/F/C). The Cs-137 reference inventory was established at 214 ± 16 Bq/m2. The mean inventories for DS, CA basins and DS/F/C were 195, 190 and 214 Bq/m2 respectively. Using the conversion Mass Balance Model 2 on the Cs-137 data obtained along transects for each of the practices, gross erosion rates were found to be 7.5, 7.3 and 2.6 t/ha/yr for direct seeding, CA basins and the DS/F/C while the net erosion rates were found to be 3.8, 4.6 and 0 t/ha/yr respectively. Sediment delivery ratios were 50%, 63% and 2% in the respective order. These preliminary results showed the effectiveness of DS over CA basins in erosion control. The efficiency of fallowing in controlling excessive soil loss was significant in the plot that started as DS for 18 years but left fallow for 7

  4. Spatial vegetation patterns and imminent desertification in Mediterranean arid ecosystems

    OpenAIRE

    2007-01-01

    Humans and climate affect ecosystems and their services, which may involve continuous and discontinuous transitions from one stable state to another. Discontinuous transitions are abrupt, irreversible and among the most catastrophic changes of ecosystems identified1. For terrestrial ecosystems, it has been hypothesized that vegetation patchiness could be used as a signature of imminent transitions. Here, we analyse how vegetation patchiness changes in arid ecosystems with different grazing pr...

  5. Evolutionary shifts in habitat aridity predict evaporative water loss across squamate reptiles.

    Science.gov (United States)

    Cox, Christian L; Cox, Robert M

    2015-09-01

    Aridity is an important determinant of species distributions, shaping both ecological and evolutionary diversity. Lizards and snakes are often abundant in deserts, suggesting a high potential for adaptation or acclimation to arid habitats. However, phylogenetic evidence indicates that squamate diversity in deserts may be more strongly tied to speciation within arid habitats than to convergent evolution following repeated colonization from mesic habitats. To assess the frequency of evolutionary transitions in habitat aridity while simultaneously testing for associated changes in water-balance physiology, we analyzed estimates of total evaporative water loss (EWL) for 120 squamate species inhabiting arid, semiarid, or mesic habitats. Phylogenetic reconstructions revealed that evolutionary transitions to and from semiarid habitats were much more common than those between arid and mesic extremes. Species from mesic habitats exhibited significantly higher EWL than those from arid habitats, while species from semiarid habitats had intermediate EWL. Phylogenetic comparative methods confirmed this association between habitat aridity and EWL despite phylogenetic signal in each. Thus, the historical colonization of arid habitats by squamates is repeatedly associated with adaptive changes in EWL. This physiological convergence, which may reflect both phenotypic plasticity and genetic adaptation, has likely contributed to the success of squamates in arid environments.

  6. Leaf protein concentrate as food supplement from arid zone plants.

    Science.gov (United States)

    Rathore, Mala

    2010-06-01

    In arid and semi-arid areas where prevalence of droughts and famines is a recurring feature, forest cover can in general make valuable contributions to food security and provide income to the rural poor. Protein and calorie malnutrition is widespread in these areas leading to high child mortality rate. Plant species can play an important role in overcoming this by being used as a source of leaf protein concentrate (LPC), a highly nutritious food. LPC should be considered seriously as it can serve as an additional protein source in the case of non-ruminants and man, especially in drought prone areas. The use of LPC in developing countries as an alternative protein source to fishmeal in broiler diet holds tremendous promise as it can substantially lower high cost of fishmeal and eventually the acute shortage of animal protein supply. Potential tropical plants for LPC production have been evaluated and selected for further research by United States Department of Agriculture. The present study was aimed to determine the potential of arid zone plants for preparation of LPC. Extraction characteristics of the several plant species have been studied and the quality of LPC prepared from them was investigated. Different fractions, chloroplastic and cytoplasmic proteins, were analyzed for their crude protein contents. Analysis of LPC shows considerable differences in their protein contents, which was found to range from 13.7 to 88.9%. Based on this, Achyranthes aspera and Tephrosia purpurea were found to be the best suited plants for LPC preparation.

  7. Saline dust storms and their ecological impacts in arid regions

    Institute of Scientific and Technical Information of China (English)

    Jilili; Abuduwaili

    2010-01-01

    In many arid and semiarid regions,saline playas represent a significant source of unconsoli-dated sediments available for aeolian transport,and severe saline dust storms occur frequently due to human disturbance.In this study,saline dust storms are reviewed systematically from the aspects of con-cept,general characteristics,conditions of occurrence,distribution and ecological impact.Our researches showed that saline dust storms are a kind of chemical dust storm originating in dry lake beds in arid and semiarid regions;large areas of unconsolidated saline playa sediments and frequent strong winds are the basic factors to saline dust storm occurrence;there are differentiation characteristics in deposition flux and chemical composition with wind-blown distance during saline dust storm diffusion;and saline dust storm diffusion to some extent increases glacier melt and results in soil salinization in arid regions.An under-standing of saline dust storms is important to guide disaster prevention and ecological rehabilitation.

  8. Changes in aridity in response to the global warming hiatus

    Science.gov (United States)

    Guan, Xiaodan; Huang, Jianping; Guo, Ruixia

    2017-02-01

    The global warming slowdown or warming hiatus, began around the year 2000 and has persisted for nearly 15 years. Most studies have focused on the interpretation of the hiatus in temperature. In this study, changes in a global aridity index (AI) were analyzed by using a newly developed dynamical adjustment method that can successfully identify and separate dynamically induced and radiatively forced aridity changes in the raw data. The AI and Palmer Drought Severity Index produced a wetting zone over the mid-to-high latitudes of the Northern Hemisphere in recent decades. The dynamical adjustment analysis suggested that this wetting zone occurred in response to the global warming hiatus. The dynamically induced AI (DAI) played a major role in the AI changes during the hiatus period, and its relationships with the North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Atlantic Multi-decadal Oscillation (AMO) also indicated that different phases of the NAO, PDO, and AMO contributed to different performances of the DAI over the Northern Hemisphere. Although the aridity wetting over the mid-to-high latitudes may relieve long-term drying in certain regions, the hiatus is temporary, and so is the relief. Accelerated global warming will return when the NAO, PDO, and AMO revert to their opposite phases in the future, and the wetting zone is likely to disappear.

  9. The influence of tillage on field scale water fluxes and maize yields in semi-arid environments: A case study of Potshini catchment, South Africa

    Science.gov (United States)

    Kosgei, J. R.; Jewitt, G. P. W.; Kongo, V. M.; Lorentz, S. A.

    Water is a limiting resource to crop production in arid and semi-arid lands (ASALs) and is responsible for substantial yield losses annually. These lands are often occupied by resource poor smallholder rainfed farmers who have little capacity to establish conventional irrigation infrastructure to mitigate recurrent droughts and dry spells. In situ water harvesting techniques in the form of conservation agriculture practices have been identified and promoted as measures that can improve soil water availability and thus enhance crop yields. Land use practices e.g. tillage influences mechanisms of lateral flow, infiltration, storage, redistribution and residence times of water at field scale. Such alterations in flow paths have not been adequately studied in ASALs where small perturbations at field scale upstream of a catchment may have significant effects downstream. Quantifying these fluxes enables better understanding of productive and non-productive water transition processes and thus to evaluate cropping and management systems. On this study the effects of tillage on water fluxes, soil physical properties and maize ( Zea mays L.) yields were examined at three sites in the Potshini catchment, South Africa. Measurements were made on plots under no-till ( NT) and conventional till ( CT) practices. Seasonal analysis indicated that nearly twice as much runoff was generated from CT treatments when compared to NT plots. However, this was not the case at the beginning of the season. The moisture content in the root zone was significantly higher in NT treatments. Maize yield was also higher in NT compared to CT plots.

  10. Grazing impacts on the susceptibility of rangelands to wind erosion: The effects of stocking rate, stocking strategy and land condition

    Science.gov (United States)

    Aubault, Hélène; Webb, Nicholas P.; Strong, Craig L.; McTainsh, Grant H.; Leys, John F.; Scanlan, Joe C.

    2015-06-01

    An estimated 110 Mt of dust is eroded by wind from the Australian land surface each year, most of which originates from the arid and semi-arid rangelands. Livestock production is thought to increase the susceptibility of the rangelands to wind erosion by reducing vegetation cover and modifying surface soil stability. However, research is yet to quantify the impacts of grazing land management on the erodibility of the Australian rangelands, or determine how these impacts vary among land types and over time. We present a simulation analysis that links a pasture growth and animal production model (GRASP) to the Australian Land Erodibility Model (AUSLEM) to evaluate the impacts of stocking rate, stocking strategy and land condition on the erodibility of four land types in western Queensland, Australia. Our results show that declining land condition, over stocking, and using inflexible stocking strategies have potential to increase land erodibility and amplify accelerated soil erosion. However, land erodibility responses to grazing are complex and influenced by land type sensitivities to different grazing strategies and local climate characteristics. Our simulations show that land types which are more resilient to livestock grazing tend to be least susceptible to accelerated wind erosion. Increases in land erodibility are found to occur most often during climatic transitions when vegetation cover is most sensitive to grazing pressure. However, grazing effects are limited during extreme wet and dry periods when the influence of climate on vegetation cover is strongest. Our research provides the opportunity to estimate the effects of different land management practices across a range of land types, and provides a better understanding of the mechanisms of accelerated erosion resulting from pastoral activities. The approach could help further assessment of land erodibility at a broader scale notably if combined with wind erosion models.

  11. Response of vegetation to drought time-scales across global land biomes.

    Science.gov (United States)

    Vicente-Serrano, Sergio M; Gouveia, Célia; Camarero, Jesús Julio; Beguería, Santiago; Trigo, Ricardo; López-Moreno, Juan I; Azorín-Molina, César; Pasho, Edmond; Lorenzo-Lacruz, Jorge; Revuelto, Jesús; Morán-Tejeda, Enrique; Sanchez-Lorenzo, Arturo

    2013-01-02

    We evaluated the response of the Earth land biomes to drought by correlating a drought index with three global indicators of vegetation activity and growth: vegetation indices from satellite imagery, tree-ring growth series, and Aboveground Net Primary Production (ANPP) records. Arid and humid biomes are both affected by drought, and we suggest that the persistence of the water deficit (i.e., the drought time-scale) could be playing a key role in determining the sensitivity of land biomes to drought. We found that arid biomes respond to drought at short time-scales; that is, there is a rapid vegetation reaction as soon as water deficits below normal conditions occur. This may be due to the fact that plant species of arid regions have mechanisms allowing them to rapidly adapt to changing water availability. Humid biomes also respond to drought at short time-scales, but in this case the physiological mechanisms likely differ from those operating in arid biomes, as plants usually have a poor adaptability to water shortage. On the contrary, semiarid and subhumid biomes respond to drought at long time-scales, probably because plants are able to withstand water deficits, but they lack the rapid response of arid biomes to drought. These results are consistent among three vegetation parameters analyzed and across different land biomes, showing that the response of vegetation to drought depends on characteristic drought time-scales for each biome. Understanding the dominant time-scales at which drought most influences vegetation might help assessing the resistance and resilience of vegetation and improving our knowledge of vegetation vulnerability to climate change.

  12. Mapping Ecological Processes and Ecosystem Services for Prioritizing Restoration Efforts in a Semi-arid Mediterranean River Basin

    Science.gov (United States)

    Trabucchi, Mattia; O'Farrell, Patrick J.; Notivol, Eduardo; Comín, Francisco A.

    2014-06-01

    Semi-arid Mediterranean regions are highly susceptible to desertification processes which can reduce the benefits that people obtain from healthy ecosystems and thus threaten human wellbeing. The European Union Biodiversity Strategy to 2020 recognizes the need to incorporate ecosystem services into land-use management, conservation, and restoration actions. The inclusion of ecosystem services into restoration actions and plans is an emerging area of research, and there are few documented approaches and guidelines on how to undertake such an exercise. This paper responds to this need, and we demonstrate an approach for identifying both key ecosystem services provisioning areas and the spatial relationship between ecological processes and services. A degraded semi-arid Mediterranean river basin in north east Spain was used as a case study area. We show that the quantification and mapping of services are the first step required for both optimizing and targeting of specific local areas for restoration. Additionally, we provide guidelines for restoration planning at a watershed scale; establishing priorities for improving the delivery of ecosystem services at this scale; and prioritizing the sub-watersheds for restoration based on their potential for delivering a combination of key ecosystem services for the entire basin.

  13. Mapping ecological processes and ecosystem services for prioritizing restoration efforts in a semi-arid Mediterranean river basin.

    Science.gov (United States)

    Trabucchi, Mattia; O'Farrell, Patrick J; Notivol, Eduardo; Comín, Francisco A

    2014-06-01

    Semi-arid Mediterranean regions are highly susceptible to desertification processes which can reduce the benefits that people obtain from healthy ecosystems and thus threaten human wellbeing. The European Union Biodiversity Strategy to 2020 recognizes the need to incorporate ecosystem services into land-use management, conservation, and restoration actions. The inclusion of ecosystem services into restoration actions and plans is an emerging area of research, and there are few documented approaches and guidelines on how to undertake such an exercise. This paper responds to this need, and we demonstrate an approach for identifying both key ecosystem services provisioning areas and the spatial relationship between ecological processes and services. A degraded semi-arid Mediterranean river basin in north east Spain was used as a case study area. We show that the quantification and mapping of services are the first step required for both optimizing and targeting of specific local areas for restoration. Additionally, we provide guidelines for restoration planning at a watershed scale; establishing priorities for improving the delivery of ecosystem services at this scale; and prioritizing the sub-watersheds for restoration based on their potential for delivering a combination of key ecosystem services for the entire basin.

  14. Diurnal and Seasonal Variation of Surface Urban Cool and Heat Islands in the Semi-Arid City of Erbil, Iraq

    Directory of Open Access Journals (Sweden)

    Azad Rasul

    2016-09-01

    Full Text Available The influence of land surface temperature (LST makes the near-surface layer of the troposphere a key driver of urban climate. This paper assesses the temporal formation of the daytime Surface Urban Cool Island (SUCI and night-time Surface Urban Heat Island (SUHI effect in Erbil, Iraq, situated in a semi-arid climate region. LST retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS Aqua and Terra and MODIS Normalized Difference Vegetation Index (NDVI from January 2003 to December 2014 are analysed. The relationships of LST with NDVI and the Normalized Multi-band Drought Index (NMDI are investigated in order to assess the influence of vegetation and moisture on the observed patterns of LST and the SUCI/SUHI. The results indicate that during the daytime, in summer, autumn and winter, densely built-up areas had lower LST acting as a SUCI compared to the non-urbanised area around the city. In contrast, at night-time, Erbil experienced higher LST and demonstrated a significant SUHI effect. The relationship between LST and NDVI is affected by seasonality and is strongly inverted during spring (r2 = 0.73; p < 0.01. Contrary to previous studies of semi-arid cities, a SUCI was detected, not only in the morning, but also during the afternoon.

  15. New evidence for effects of land cover in China on summer climate

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The effects of land cover in different regions of China on summer climate are studied by lagged correlation analysis using NOAA/AVHRR normalized difference vegetation index (NDVI) data for the period of 1981-1994 and temperature,precipitation data of 160 meteorological stations in China. The results show that the correlation coefficients between NDVI in previous season and summer precipitation are positive in most regions of China, and the lagged correlations showa significant difference between regions. The stronger correlations between NDVI in previous winter and precipitation in summer occur in Central China and the Tibetan Plateau, and the correlations between spring NDVI and summer precipitation in the eastern arid/semi- arid region and the Tibetan Plateau are more significant. Vegetation changes have more sensitive feedback effects on climate in thethree regions (eastern arid/semi-arid region, Central China and Tibetan Plateau). The lagged correlations between NDVI and precipitation suggest that, on interannual time scales, land cover affects summer precipitation to a certain extent.The correlations between NDVI in previous season and summer temperature show more complex, and the lagged responses of temperature to vegetation are weaker compared with precipitation, and they are possibly related to the global warming which partly cover up the correlations.

  16. Analysing the Effects of Different Land Cover Types on Land Surface Temperature Using Satellite Data

    Science.gov (United States)

    Şekertekin, A.; Kutoglu, Ş. H.; Kaya, S.; Marangoz, A. M.

    2015-12-01

    Monitoring Land Surface Temperature (LST) via remote sensing images is one of the most important contributions to climatology. LST is an important parameter governing the energy balance on the Earth and it also helps us to understand the behavior of urban heat islands. There are lots of algorithms to obtain LST by remote sensing techniques. The most commonly used algorithms are split-window algorithm, temperature/emissivity separation method, mono-window algorithm and single channel method. In this research, mono window algorithm was implemented to Landsat 5 TM image acquired on 28.08.2011. Besides, meteorological data such as humidity and temperature are used in the algorithm. Moreover, high resolution Geoeye-1 and Worldview-2 images acquired on 29.08.2011 and 12.07.2013 respectively were used to investigate the relationships between LST and land cover type. As a result of the analyses, area with vegetation cover has approximately 5 ºC lower temperatures than the city center and arid land., LST values change about 10 ºC in the city center because of different surface properties such as reinforced concrete construction, green zones and sandbank. The temperature around some places in thermal power plant region (ÇATES and ZETES) Çatalağzı, is about 5 ºC higher than city center. Sandbank and agricultural areas have highest temperature due to the land cover structure.

  17. ANALYSING THE EFFECTS OF DIFFERENT LAND COVER TYPES ON LAND SURFACE TEMPERATURE USING SATELLITE DATA

    Directory of Open Access Journals (Sweden)

    A. Şekertekin

    2015-12-01

    Full Text Available Monitoring Land Surface Temperature (LST via remote sensing images is one of the most important contributions to climatology. LST is an important parameter governing the energy balance on the Earth and it also helps us to understand the behavior of urban heat islands. There are lots of algorithms to obtain LST by remote sensing techniques. The most commonly used algorithms are split-window algorithm, temperature/emissivity separation method, mono-window algorithm and single channel method. In this research, mono window algorithm was implemented to Landsat 5 TM image acquired on 28.08.2011. Besides, meteorological data such as humidity and temperature are used in the algorithm. Moreover, high resolution Geoeye-1 and Worldview-2 images acquired on 29.08.2011 and 12.07.2013 respectively were used to investigate the relationships between LST and land cover type. As a result of the analyses, area with vegetation cover has approximately 5 ºC lower temperatures than the city center and arid land., LST values change about 10 ºC in the city center because of different surface properties such as reinforced concrete construction, green zones and sandbank. The temperature around some places in thermal power plant region (ÇATES and ZETES Çatalağzı, is about 5 ºC higher than city center. Sandbank and agricultural areas have highest temperature due to the land cover structure.

  18. Quantifying macropore recharge: Examples from a semi-arid area

    Science.gov (United States)

    Wood, W.W.; Rainwater, K.A.; Thompson, D.B.

    1997-01-01

    The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered to be the difference between total recharge through floors of topographically dosed basins and interstitial recharge through the same area. On the regional scale, macropore recharge was considered to be the difference between regional average annual recharge and interstitial recharge measured in the unsaturated zone. Stable isotopic composition of ground water and precipitation was used us an independent estimate of macropore recharge on the regional scale. Results of this analysis suggest that in the Southern High Plains recharge flux through macropores is between 60 and 80 percent of the total 11 mm/y. Between 15 and 35 percent of the recharge occurs by interstitial recharge through the basin floors. Approximately 5 percent of the total recharge occurs as either interstitial or matrix recharge between the basin floors, representing approximately 95 percent of the area. The approach is applicable to other arid and semi-arid areas that focus rainfall into depressions or valleys.The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in arid and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered

  19. Coupling stable isotope and satellite to inform a snow accumulation and melt model for data poor, semi-arid watersheds

    Science.gov (United States)

    Hublart, Paul; Sproles, Eric; Soulsby, Chris; Tetzlaff, Doerthe; Hevía, Andres

    2016-04-01

    At the most basic level watersheds catch, store, and release water. In semi-arid northern central Chile (29°-32°) snow and glacier melt dominate these basic hydrological stages. In this region precipitation is typically limited to three to five events per year that falls as snow in the High Cordillera at elevations above 3000 m a.s.l. The rugged topography and steep gradient makes snowfall rates highly variable in space and time. Despite its critical importance for water supply, high elevation meteorological data and measurements of snowpack are scarce due to limited winter access above 3000 m a.s.l. Due to the critically limited understanding of catch, store, and release processes most conceptual watershed models for this region remain speculative, are prone to over-parameterization, and greatly inhibits hydrological prediction in the region. Focused on two headwater watersheds of the Elqui River basin (1615-6040 m a.s.l., 429-566 km2) this study couples stable isotope and Moderate Resolution Imaging Spectrometer (MODIS) data to develop an improved conceptual model of how semi-arid mountain watersheds catch, store, and release water. MODIS snow-cover and land surface temperature data are used to inform an enhanced temperature-index Snow Accumulation and Melt (SAM) model. The use of remotely-sensed temperature data as input to this model is evaluated by comparison with an interpolated dataset derived from a few available meteorological stations. The outputs from the SAM model are used as inputs to a conceptual catchment model including two water stores (one standing for surface/subsurface processes and the other for deeper groundwater storage). The model is calibrated and evaluated from a Bayesian perspective using discharge data measured at the catchment outlets over a 15-year period (2000-2015). Stable isotope data collected during 2015-2016 is applied to better constrain model outputs. The combination of MODIS-based and isotope-based information proves very

  20. A Proposal on the Restoration of Nostoc flagelliforme for Sustainable Improvement in the Ecology of Arid Steppes in China

    Directory of Open Access Journals (Sweden)

    Xiang Gao

    2016-06-01

    Full Text Available Nostoc flagelliforme, a filamentous nitrogen-fixing cyanobacterium, is widely distributed in arid steppes of the west and northwestern parts of China. However, as a food delicacy this species has been overexploited from 1970 to 2000. Moreover, overgrazing, land reclamation and the removal of medicinal herbs have caused severely reduced vegetation coverage there. In this communication, a badly damaged but slowly rehabilitating N. flagelliforme-inhibiting steppe is described, and the rehabilitation of desertified steppes by the renewed growth of N. flagelliforme is proposed. The restoration of this dominant nitrogen supplier would be an ecologically sustainable solution for supplementing current measures already taken in the desertified regions. In addition, a goal of 50%–60% vegetation coverage is proposed by the N. flagelliforme restoration.

  1. Building resilience to social-ecological change through farmers' learning practices in semi-arid Makueni County Kenya

    Science.gov (United States)

    Ifejika Speranza, Chinwe; Kiteme, Boniface; Kimathi Mbae, John; Schmude, Miron

    2015-04-01

    Social-ecological change is resulting in various risks and opportunities to farmers, which they address through complex multi-strategies to sustain their agricultural-based livelihoods and agricultural landscapes. This paper examines how various stakeholders such as research and government organisations, local and international non-governmental organisations, private companies, farmer groups, individual actors and farmers draw on scientific, external and localised knowledge to address the needs of farmers in sustainable land management and food production. What is the structure of collaboration between the various actors and how does this influence the potential for learning, not only for the farmers but also for other stakeholders? How does the supplied knowledge meet farmers' knowledge needs and demands for sustainable land management and food production? To what extent and how is knowledge co-produced among the various stakeholders? What different types of learning can be identified and what are their influences on farmers' sustainable land management practices? How does farmer learning foster the resilience of agricultural landscapes? Answers to these questions are sought through a case study in the semi-arid areas of Makueni County, Kenya. Particular environmental risks in the study area relate to recurrent droughts and flooding, soil erosion and general land degradation. Opportunities in the study area arise short-term due to more conducive rainfall conditions for crop and vegetation growth, institutional arrangements that foster sustainable land management such as agroforestry programmes and conservation agriculture projects. While farmers observe changes in their environment, they weigh the various risks and opportunities that arise from their social-ecological context and their own capacity to respond leading to the prioritization of certain adaptations relative to others. This can mean that while certain farmers may have knowledge on sustainable land

  2. ARID1A immunohistochemistry improves outcome prediction in invasive urothelial carcinoma of urinary bladder.

    Science.gov (United States)

    Faraj, Sheila F; Chaux, Alcides; Gonzalez-Roibon, Nilda; Munari, Enrico; Ellis, Carla; Driscoll, Tina; Schoenberg, Mark P; Bivalacqua, Trinity J; Shih, Ie-Ming; Netto, George J

    2014-11-01

    AT-rich interactive domain 1A (ARID1A) is tumor suppressor gene that interacts with BRG1 adenosine triphosphatase to form a SWI/SNF chromatin remodeling protein complex. Inactivation of ARID1A has been described in several neoplasms, including epithelial ovarian and endometrial carcinomas, and has been correlated with prognosis. In the current study, ARID1A expression in urothelial carcinoma (UC) of the bladder and its association with clinicopathological parameters and outcome are addressed. Five tissue microarrays were constructed from 136 cystectomy specimens performed for UC at our institution. Nuclear ARID1A staining was evaluated using immunohistochemistry. An H-score was calculated as the sum of the products of intensity (0-3) multiplied by extent of expression (0%-100%). Average H-score per case was used for statistical analysis. ARID1A expression was categorized in low and high using Youden index to define the cut point. ARID1A expression significantly increased from normal to noninvasive UC to invasive UC. For both tumor progression and cancer death, Youden index yielded an H-score of 288 as the optimal cut point for ARID1A expression. Low ARID1A expression showed a tendency for lower risk of tumor progression and cancer mortality. Adding ARID1A expression to pathologic features offers a better model for predicting outcome than pathologic features alone. Low ARID1A expression was more frequently seen in earlier stage disease. There was a tendency for low ARID1A expression to predict better outcome. More importantly, the findings indicate that adding ARID1A expression to pathologic features increases the goodness of fit of the predictive model.

  3. Impact of Reforestation on Local Climate and Environment in a Semi-arid Urban Valley, Northwestern China

    Science.gov (United States)

    Xia, D.; Yu, Y.; He, J.

    2015-12-01

    Since 1999 Chinese government has invested more than 800 million Yuan to reforest the southern and the northern mountains surrounding urban Lanzhou - a typical semi-arid city located in a river valley, Northwestern China. Until 2009 obvious land use change occurred, with 69.2% of the reforested area been changed from grasslands, croplands, barren or sparsely vegetated land to closed shrublands and 20.6% been changed from closed shrublands, grasslands, and croplands to forests. This study assesses the impact of these changes on local climate and environment in winter using WRF (Weather Research & Forecasting) model incorporated with high-resolution remotely sensed land cover data for 1999 and 2009 and the FLEXible PARTicle (FLEXPART) dispersion model. Results indicate that the changes in albedo, surface exchange coefficient and surface soil heat conductivity related to the reforestation led to the changes in surface net radiation and the surface energy partitioning, which in turn affected the meteorology fields and enhanced the mountain-valley wind circulation. The amount of air exchanged between the valley and the outside increased after reforestation during the day, with the largest increase of 10 %, while it changed little during the night on winter sunny day with no snow cover. The sensitivity analysis using FLEXPART-WRF model indicates that the reforestation affected the spatial distribution of pollutants and slightly improved the urban air quality in winter. And the greening program of Lanzhou has special reference to other valley urbans.

  4. Androgen Receptor Coactivator ARID4B Is Required for the Function of Sertoli Cells in Spermatogenesis.

    Science.gov (United States)

    Wu, Ray-Chang; Zeng, Yang; Pan, I-Wen; Wu, Mei-Yi

    2015-09-01

    Defects in spermatogenesis, a process that produces spermatozoa inside seminiferous tubules of the testis, result in male infertility. Spermatogenic progression is highly dependent on a microenvironment provided by Sertoli cells, the only somatic cells and epithelium of seminiferous tubules. However, genes that regulate such an important activity of Sertoli cells are poorly understood. Here, we found that AT-rich interactive domain 4B (ARID4B), is essential for the function of Sertoli cells to regulate spermatogenesis. Specifically, we generated Sertoli cell-specific Arid4b knockout (Arid4bSCKO) mice, and showed that the Arid4bSCKO male mice were completely infertile with impaired testis development and significantly reduced testis size. Importantly, severe structural defects accompanied by loss of germ cells and Sertoli cell-only phenotype were found in many seminiferous tubules of the Arid4bSCKO testes. In addition, maturation of Sertoli cells was significantly delayed in the Arid4bSCKO mice, associated with delayed onset of spermatogenesis. Spermatogenic progression was also defective, showing an arrest at the round spermatid stage in the Arid4bSCKO testes. Interestingly, we showed that ARID4B functions as a "coactivator" of androgen receptor and is required for optimal transcriptional activation of reproductive homeobox 5, an androgen receptor target gene specifically expressed in Sertoli cells and critical for spermatogenesis. Together, our study identified ARID4B to be a key regulator of Sertoli cell function important for male germ cell development.

  5. Review of several problems on the study of eco-hydrological processes in arid zones

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Ecosystem degradation is a common and cardinal environmental problem in arid zones. The change in the eco-hydrological processes is the basic cause responsible for such a problem. The study on the eco-hydrological processes in arid zones has become a forefront and focus of the eco-environmental research. Recent studies on eco-hydrological processes in arid zones show that the primary vegetation pattern and its eco-hydrological effect are of the most stable state of the ecosystem in arid zones. Special water absorption ways of plants in arid zones and the hydraulic lift and reverse hydraulic lift functions of some plants are the key mechanisms to maintain the stability of the ecosystem in arid zones. In the case of water shortage, ensuring ecological water requirement and maintaining proper ecological ground- water table are the prerequisite to keep healthful operation of the ecosystem in arid zones. The paper reviews some advances in the study of eco-hydrological processes in arid zones. It puts forward the concepts of critical ecological water requirement, optimal ecological water requirement and saturated ecological water requirement, and discusses their determination methods. It also emphasizes that the studies on natural vegetation pattern and eco-hydrological effect, on plants with hydraulic lift function, on water sources for plant absorption, on ecological water requirement and ecological groundwater table for different plant species should be strengthened to determine the species composition and pattern suitable for the restoration and reestablishment of vegetation in different arid zones in China.

  6. Assessment of desertification risk in semi-arid Mediterranean environments: the case study of Apulia region (Southern Italy)

    Science.gov (United States)

    Ladisa, Gaetano; Todorovic, Mladen; Trisorio Liuzzi, Giuliana

    2010-05-01

    This work focuses on the risk assessment of the areas threatened with desertification in the semi-arid Mediterranean environments. The presented approach uses as a reference the ESAs model (Environmental Sensitive Areas to Desertification; Kosmas et al., 1999) which is modified through a set of new indicators which take into account the region-specific environmental characteristics as well as identifiable parameters relevant for planning control measures. These supplementary indicators, comprehending socio-economic and environmental factors, are integrated in the ESAs model and, by using a GIS, applied to Apulia region (Southern Italy). This area represents a typical Mediterranean landscape affected by land degradation and desertification risks. The analyses include the elaboration of the whole set of indices on both the regional and the administrative scales which constitute the principal territorial units for the management of natural resources. The results have demonstrated that the introduction of the new indices has improved substantially the overall evaluation of the desertification risk in the Apulia region. The proposed approach permits not only the identification and refinement of different degrees of sensibility of an area to land degradation, but also the analyses of the factors affecting desertification and their evaluation in terms of spatial and temporal distribution. Moreover, the presented method is conceptually very simple and easy to implement from local to regional and national scale, and can be proposed as a methodology for the definition of priorities in adoption of strategies to mitigate desertification in the semi-arid Mediterranean environments. Key words: desertification risk, sensitivity areas, Apulia region, Mediterranean environment.

  7. An ecological engineering approach for keeping water from reaching interred wastes in arid or semiarid regions

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J.E. [Idaho State Univ., Pocatello, ID (United States)

    1997-12-31

    This paper describes application of a soil-plant cover system (SPCS) to preclude water from reaching interred wastes in arid and semiarid regions. Where potential evapotranspiration far exceeds precipitation, water can be kept from reaching buried wastes by (1) providing a sufficiently deep cap of soil to store precipitation that falls while plants are dormant and (2) maintaining plant cover to deplete soil moisture during the growing season, thereby emptying the storage reservoir. Research at the Idaho National Engineering Laboratory (INEL) has shown that 2 m of soil is adequate to store moisture from snowmelt and spring rains. Healthy stands of perennial grasses and shrubs adapted to the INEL climate use all available soil moisture, even during a very wet growing season. However, burrowing by small mammals or ants may affect the performance of a SPCS by increasing infiltration of water. Intrusion barriers of gravel and cobble can be used to restrict burrowing, but emplacement of such barriers affects soil moisture storage and plant rooting depths. A replicated field experiment to investigate the implications of those effects is in progress. Incorporation of an SPCS should be considered in the design of isolation barriers for shallow land burial of hazardous wastes in and regions.

  8. Ecosystem services provided by agricultural terraces in semi-arid climates.

    Science.gov (United States)

    Romero-Díaz, Asunción; Díaz-Pereira, Elvira; Boix-Fayos, Carolina; de Vente, Joris

    2016-04-01

    Since ancient times, agricultural terraces are common features throughout the world, especially on steep slope gradients. Nowadays many terraces have been abandoned or removed and few new terraces are build due to increased mechanisation and intensification of agriculture. However, terraces are amongst the most effective soil conservation practices, reducing the slope gradient and slope length, as well as runoff rate and soil erosion, and without terraces, it would be impossible to cultivate on many hillslopes. Moreover, their scenic interest is undeniable, as in some cases, terraced slopes have even become part of UNESCO World Heritage. In order to highlight the potential benefits, requirements and limitations of terraces, we reviewed different types of sustainable land management practices related to terraces and characterised their implications for provisioning, regulating, supporting, and cultural ecosystem services. We centred our review on terraces in semi-arid environments worldwide, as were documented in the WOCAT (World Overview of Conservation Approaches and Technologies) database. Our results show that the most important ecosystem services provided by terraces relate to regulation of the on-site and off-site effects of runoff and erosion, and maintenance of soil fertility and vegetation cover. The presence of terraces also favours the provision of food, fiber, and clean water. In short, our results stress the crucial environmental, geomorphological and hydrological functions of terraces that directly relate to improving the quality of life of the people that use them. These results highlight the need for renewed recognition of the value of terraces for society, their preservation and maintenance.

  9. The oasis effect and summer temperature rise in arid regions - case study in Tarim Basin

    Science.gov (United States)

    Hao, Xingming; Li, Weihong; Deng, Haijun

    2016-10-01

    This study revealed the influence of the oasis effect on summer temperatures based on MODIS Land Surface Temperature (LST) and meteorological data. The results showed that the oasis effect occurs primarily in the summer. For a single oasis, the maximum oasis cold island intensity based on LST (OCILST) was 3.82 °C and the minimum value was 2.32 °C. In terms of the annual change in OCILST, the mean value of all oases ranged from 2.47 °C to 3.56 °C from 2001 to 2013. Net radiation (Rn) can be used as a key predictor of OCILST and OCItemperature (OCI based on air temperature). On this basis, we reconstructed a long time series (1961–2014) of OCItemperature and Tbase(air temperature without the disturbance of oasis effect). Our results indicated that the reason for the increase in the observed temperatures was the significant decrease in the OCItemperature over the past 50 years. In arid regions, the data recorded in weather stations not only underestimated the mean temperature of the entire study area but also overestimated the increasing trend of the temperature. These discrepancies are due to the limitations in the spatial distribution of weather stations and the disturbance caused by the oasis effect.

  10. Evaluation of advection-aridity complementary relations at the lab scale

    Science.gov (United States)

    Schymanski, Stanislaus J.; Aminzadeh, Milad; Roderick, Michael L.; Or, Dani

    2015-04-01

    A common view of evaporation from terrestrial surfaces considers limitations due to water supply in arid regions, and atmospheric demand (or energy) limitations to evaporation from wet surfaces in temperate regions. Evidence suggests that at large scales, energy and water limitations are not independent. While a surface dries and a larger fraction of the radiative energy is converted into sensible heat, that heat is injected into the air and altering its properties. This land-atmosphere feedback gives rise to the so-called complementary relationship (Bouchet 1963), referring to the simultaneous decrease in actual evaporation while potential evaporation increases as the surface dries. The effect of surface drying on atmospheric water demand is two-fold: an increase in air temperature and a decrease in water vapour content for fixed advective exchange rate across the system boundaries. To isolate the various mechanisms and improve understanding of the feedbacks, we designed an insulated wind tunnel, where wind speed, radiation, surface moisture and exchange rates of air and heat across the boundaries are controlled. Preliminary results show the magnitude of the feedbacks in terms of air and surface temperatures, and evaporation rates from drying and wet surfaces simultaneously. Experimental and associated simulation results provide a direct demonstration of the roles of advective exchange and the interplay between atmospheric boundary layer thickness and temporal variations in radiative energy input in determining the strength of surface-atmosphere feedbacks and the resulting phenomenon known as the complementary relationship.

  11. Water Budget Analysis in Arid Regions, Application to the United Arab Emirates

    Directory of Open Access Journals (Sweden)

    Rocio Gonzalez

    2016-09-01

    Full Text Available Population growth and economic development have impacted the capacity of water resources to meet demands in a number of arid countries. This study focuses on the United Arab Emirates (UAE where low rainfall, high rate of growth and agricultural development are resulting in a dramatic depletion of groundwater resources and an increased dependence on desalination. A water budget for the region was developed. It represents the variations in groundwater storage as a balance of total precipitation, desalinated water and evapotranspiration. The components of the water budget are obtained from ground observations, documented information, models and remote sensing data, using Gravity Recovery and Climate Experiment (GRACE satellites to estimate changes in groundwater storage and Tropical Rainfall Measuring Mission (TRMM satellites and Global Land Data Assimilation System (GLDAS data to obtain precipitation and soil moisture respectively. Results show a negative trend of 0.5 cm/year in groundwater levels corresponding to an average decrease of 0.86 km3/year during the study period (2003 to 2012. This negative trend indicates that the aquifers are not being recharged fast enough to compensate for human withdrawals. Most of the precipitation was found to be lost through evapotranspiration. A discussion of the current water budget components is presented and propositions are made for a sustainable use of water resources in the UAE, including a more efficient use of recycled water. This analysis is applicable to other Gulf countries and it can help to determine the optimal allocation of water resources to optimize agricultural productivity.

  12. Human-Wildlife Conflicts in Arid Areas of Western India: Strategies for Mutual Co-Existence

    Directory of Open Access Journals (Sweden)

    Darshana Patel

    2014-04-01

    Full Text Available The study has been carried out in the North Gujarat region of Gujarat state, Western India which represents unique habitats from arid regions to dry deciduous forests with annual rainfall ranging from 25-125 cms. Human-wildlife conflicts are intensifying owing to increase in human population and destruction of wildlife habitats. In the present study we characterized and classified the conflicts, identified zones with acute conflicts and evaluated the economic loss to the local villagers due to such humanwildlife conflicts. Sampling methods mainly included village surveys for interviewing locals who are affected by wildlife damage. The information was overlaid on the existing digital land use data to identify landscape characteristics associated with wildlife occupancy in the region. The result depicts that 80% of total damage in seasonal crop is caused by wild ungulates. Wild animals like Blue bull, Wild boar and Porcupine are reported as a chief crop raider. The Leopard is the only big cat occurring in the region reported to cause human injury and livestock predation. Sloth bear attacks on human are very common in some part of the study area. Conflicts are more severe around unprotected forests while high intensity of conflicts was recorded on the fringes of the forests

  13. Evaluating pasture and soil allowance of manganese for Kajli rams grazing in semi-arid environment.

    Science.gov (United States)

    Khan, Zafar Iqbal; Ahmad, Kafeel; Ashraf, Muhammad; Naqvi, Syed Ali Hassan; Seidavi, Alireza; Akram, Nudrat Aisha; Laudadio, Vito; Tufarelli, Vincenzo

    2015-03-01

    The current research on the manganese (Mn) transfer from soil to plant as well as to grazing Kajli rams in the form of sampling periods was carried out under semi-arid environmental conditions. Forage, soil and blood plasma samples were collected during 4 months of the year after a 1-month interval, and Mn concentrations were assessed after wet digestion using an atomic absorption spectrophotometer. Results showed that Mn concentration in soil ranged from 48.28 to 59.44 mg/kg, with incoherent augment and decline across sampling periods, and effect of sampling period on soil Mn was also found to be significant (P crop requirement. The Mn concentration in forage ranged between 24.8 and 37.2 mg/kg, resulting deficient based on the requirement allowance of Mn for livestock grazing animals, therein with almost unchanged forage Mn concentration. The Mn values in blood plasma of rams varied from 0.066 to 0.089 mg/l, with a consistent increase based on sampling period, and the effect of sampling periods on plasma Mn was found to be highly significant (P crop residues and mixed pasture and a pronounced seasonal supply of Mn at the four sampling period of grazing land of diverse botanical composition.

  14. Developing an Understanding of Vegetation Change and Fluvial Carbon Fluxes in Semi-Arid Environments

    Science.gov (United States)

    Puttock, A.; Brazier, R. E.; Dungait, J. A. J.; Bol, R.; Macleod, C. J. A.

    2012-04-01

    Dryland environments are estimated to cover around 40% of the global land surface (Okin et al, 2009) and are home to approximately 2.5 billion people (Reynolds et al. 2007). Many of these areas have recently experienced extensive land degradation. One such area and the focus of this project is the semi-arid US Southwest, where degradation over the past 150 years has been characterised by the invasion of woody vegetation into grasslands. Transition from grass to woody vegetation results in a change in ecosystem structure and function (Turnbull et al, 2008). Structural change is typically characterised by an increased heterogeneity of soil and vegetation resources, associated with reduced vegetation coverage and an increased vulnerability to soil erosion and the potential loss of key nutrients to adjacent fluvial systems. Such loss of resources may impact heavily upon the amount of carbon that is sequestered by these environments and the amount of carbon that is lost as the land becomes more degraded. Therefore, understanding these vegetation transitions is significant for sustainable land use and global biogeochemical cycling. This project uses an ecohydrological approach, monitoring natural rainfall-runoff events over six bounded plots with different vegetation coverage. The experiment takes advantage of a natural abundance stable 13C isotope shift from C3 piñon-juniper (Pinus edulis-Juniperus monosperma) mixed stand through a C4 pure-grass (Bouteloua eriopoda) to C3 shrub (Larrea tridentata). Data collected quantify fluvial fluxes of sediment and associated soil organic matter and carbon that is lost from across the grass-to-shrub and grass-to-woodland transition (where change in space is taken to indicate a similar change through time). Results collected during the 2010 and 2011 monsoon seasons will be presented, illustrating that soil and carbon losses are greater as the ecosystem becomes more dominated by woody plants. Additionally this project utilises novel

  15. Evaluating the Potential of PROBA-V Satellite Image Time Series for Improving LC Classification in Semi-Arid African Landscapes

    Directory of Open Access Journals (Sweden)

    Johannes Eberenz

    2016-11-01

    Full Text Available Satellite based land cover classification for Africa’s semi-arid ecosystems is hampered commonly by heterogeneous landscapes with mixed vegetation and small scale land use. Higher spatial resolution remote sensing time series data can improve classification results under these difficult conditions. While most large scale land cover mapping attempts rely on moderate resolution data, PROBA-V provides five-daily time series at 100 m spatial resolution. This improves spatial detail and resilience against high cloud cover, but increases the data load. Cloud-based processing platforms can leverage large scale land cover monitoring based on such finer time series. We demonstrate this with PROBA-V 100 m time series data from 2014–2015, using temporal metrics and cloud filtering in combination with in-situ training data and machine learning, implemented on the ESA (European Space Agency Cloud Toolbox infrastructure. We apply our approach to two use cases for a large study area over West Africa: land- and forest cover classification. Our land cover classification reaches a 7% to 21% higher overall accuracy when compared to four global land cover maps (i.e., Globcover-2009, Cover-CCI-2010, MODIS-2010, and Globeland30. Our forest cover classification shows 89% correspondence with the Tropical Ecosystem Environment Observation System (TREES-3 forest cover data which is based on spatially finer Landsat data. This paper illustrates a proof of concept for cloud-based “big-data” driven land cover monitoring. Furthermore, we show that a wide range of temporal metrics can be extracted from detailed PROBA-V 100 m time series data to continuously optimize land cover monitoring.

  16. An Approach for Simulating Soil Loss from an Agro-Ecosystem Using Multi-Agent Simulation: A Case Study for Semi-Arid Ghana

    Directory of Open Access Journals (Sweden)

    Biola K. Badmos

    2015-07-01

    Full Text Available Soil loss is not limited to change from forest or woodland to other land uses/covers. It may occur when there is agricultural land-use/cover modification or conversion. Soil loss may influence loss of carbon from the soil, hence implication on greenhouse gas emission. Changing land use could be considered actually or potentially successful in adapting to climate change, or may be considered maladaptation if it creates environmental degradation. In semi-arid northern Ghana, changing agricultural practices have been identified amongst other climate variability and climate change adaptation measures. Similarly, some of the policies aimed at improving farm household resilience toward climate change impact might necessitate land use change. The heterogeneity of farm household (agents cannot be ignored when addressing land use/cover change issues, especially when livelihood is dependent on land. This paper therefore presents an approach for simulating soil loss from an agro-ecosystem using multi-agent simulation (MAS. We adapted a universal soil loss equation as a soil loss sub-model in the Vea-LUDAS model (a MAS model. Furthermore, for a 20-year simulation period, we presented the impact of agricultural land-use adaptation strategy (maize cultivation credit i.e., maize credit scenario on soil loss and compared it with the baseline scenario i.e., business-as-usual. Adoption of maize as influenced by maize cultivation credit significantly influenced agricultural land-use change in the study area. Although there was no significant difference in the soil loss under the tested scenarios, the incorporation of human decision-making in a temporal manner allowed us to view patterns that cannot be seen in single step modeling. The study shows that opening up cropland on soil with a high erosion risk has implications for soil loss. Hence, effective measures should be put in place to prevent the opening up of lands that have high erosion risk.

  17. Mapping Annual Forest Cover in Sub-Humid and Semi-Arid Regions through Analysis of Landsat and PALSAR Imagery

    Directory of Open Access Journals (Sweden)

    Yuanwei Qin

    2016-11-01

    Full Text Available Accurately mapping the spatial distribution of forests in sub-humid to semi-arid regions over time is important for forest management but a challenging task. Relatively large uncertainties still exist in the spatial distribution of forests and forest changes in the sub-humid and semi-arid regions. Numerous publications have used either optical or synthetic aperture radar (SAR remote sensing imagery, but the resultant forest cover maps often have large errors. In this study, we propose a pixel- and rule-based algorithm to identify and map annual forests from 2007 to 2010 in Oklahoma, USA, a transitional region with various climates and landscapes, using the integration of the L-band Advanced Land Observation Satellite (ALOS PALSAR Fine Beam Dual Polarization (FBD mosaic dataset and Landsat images. The overall accuracy and Kappa coefficient of the PALSAR/Landsat forest map were about 88.2% and 0.75 in 2010, with the user and producer accuracy about 93.4% and 75.7%, based on the 3270 random ground plots collected in 2012 and 2013. Compared with the forest products from Japan Aerospace Exploration Agency (JAXA, National Land Cover Database (NLCD, Oklahoma Ecological Systems Map (OKESM and Oklahoma Forest Resource Assessment (OKFRA, the PALSAR/Landsat forest map showed great improvement. The area of the PALSAR/Landsat forest was about 40,149 km2 in 2010, which was close to the area from OKFRA (40,468 km2, but much larger than those from JAXA (32,403 km2 and NLCD (37,628 km2. We analyzed annual forest cover dynamics, and the results show extensive forest cover loss (2761 km2, 6.9% of the total forest area in 2010 and gain (3630 km2, 9.0% in southeast and central Oklahoma, and the total area of forests increased by 684 km2 from 2007 to 2010. This study clearly demonstrates the potential of data fusion between PALSAR and Landsat images for mapping annual forest cover dynamics in sub-humid to semi-arid regions, and the resultant forest maps would be

  18. Assessment of Plant Functional Types in Tropical Arid and Semi-Arid Ecosystems of India Using Remote Sensing Data and GIS

    Science.gov (United States)

    Sudhakar Reddy, C.; Krishna, P. Hari; Murthy, M. S. R.

    2011-09-01

    vegetation systems were studied along arid, semi-arid and sub-humid regions of Indian Desert and Aravallis of Rajasthan, India, with a distance of 600 km. The annual precipitation decreases from as high as 1600 mm in the south to 700 mm in the north-east and 100 mm in the west. The study is based on the integrated approach of remote sensing, GIS, and phytosociology. In the step 1, vegetation type map was prepared using multi-season IRS P6 LISS III data. Screening of plant traits was done based on field observations and literature. Phytosociological data pertains to 500 sample plots was used to identify plant functional traits of 900 species at morphological level. The vegetation classification scheme at regional level identified thorn forest, dry deciduous forest, broad leaved forest, woodland, shrubland and grasslands. Five plant traits selected in the study were significant for tropical environments. Attributes such as leaf size, leaf texture, spinescence, stem diameter and bark consistency were categorized systematically. Ordination analysis was carried out across the environmental gradient. Plant functional traits were measured on 20 individuals per species at each site. Environmental information was integrated to identify plant trait response. The spatial trends in PFTs were analysed and compared across the vegetation types, along the gradient of land surface temperature, climate, elevation and time integrated NDVI. Results established the occurrence of recurrent patterns of association among selected plant traits. Functional response groups were identified by summarizing results and relating them to individual species. Finally phytoclimatic map was prepared to represent spatial distribution of PFTs. The species with of functional traits of representing microphylls, sclerophyll, rough bark, spinescence and therophyte are demarcated as drought tolerant traits. Drought Intolerant PFTs are represented by macrophyll, malacophyll, smooth Bark, non spinescent stems and leaves

  19. Understanding Hydrologic Processes in Semi-Arid Cold Climates

    Science.gov (United States)

    Barber, M. E.; Beutel, M.; Lamb, B.; Watts, R.

    2004-12-01

    Water shortages destabilize economies and ecosystems. These shortages are caused by complex interactions between climate variability, ecosystem processes, and increased demand from human activities. In the semi-arid region of the northwestern U.S., water availability during drought periods has already reached crisis levels and the problems are expected to intensify as the effects of global climate change and population growth continue to alter the supply and demand patterns. Many of the problems are critical to this region because hydropower, agriculture, navigation, fish and wildlife survival, water supply, tourism, environmental protection, and water-based recreation are vital to state economies and our way of life. In order to assess the spatial and temporal nature of hydrologic responses, consistent and comprehensive long-term data sets are needed. In response to these needs, we would like to propose the Spokane River drainage basin as a long-term hydrologic observatory. The Spokane River basin is located in eastern Washington and northern Idaho and is a tributary of the Columbia River. The watershed consists of several major surface water tributaries as well as natural and man-made lakes and reservoirs. With headwaters beginning in the Rocky Mountains, the drainage area is approximately 6,640 mi2. In addition to providing an excellent study area for examining many conventional water resource problems, the Spokane River watershed also presents a unique opportunity for investigating many of the hydrologic processes found in semi-arid cold climates. Snowfall in the watershed varies spatially between 35 inches near the mouth of the basin to over 112 inches at the headwaters. These varied hydrologic uses provide a unique opportunity to address many common challenges faced by water resource professionals. This broad array of issues encompasses science, engineering, agriculture, social sciences, economics, fisheries, and a host of other disciplines. In addition

  20. Improved climate risk simulations for rice in arid environments.

    Science.gov (United States)

    van Oort, Pepijn A J; de Vries, Michiel E; Yoshida, Hiroe; Saito, Kazuki

    2015-01-01

    We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potential yields with yields simulated with default ORYZA2000, with modified subversions of ORYZA2000 and with ORYZA_S, a model developed for the region of interest in the 1990s. Rice variety 'IR64' was sown monthly 15-times in a row in two locations in Senegal. The Senegal River Valley is located in the Sahel, near the Sahara desert with extreme temperatures during day and night. The existing subroutines underestimated cold stress and overestimated heat stress. Forcing the model to use observed spikelet number and phenology and replacing the existing heat and cold subroutines improved accuracy of yield simulation from EF = -0.32 to EF =0.70 (EF is modelling efficiency). The main causes of improved accuracy were that the new model subversions take into account transpirational cooling (which is high in arid environments) and early morning flowering for heat sterility, and minimum rather than average temperature for cold sterility. Simulations were less accurate when also spikelet number and phenology were simulated. Model efficiency was 0.14 with new heat and cold routines and improved to 0.48 when using new cardinal temperatures for phenology and early leaf growth. The new adapted subversion of ORYZA2000 offers a powerful analytic tool for climate change impact assessment and cropping calendar optimisation in arid regions.

  1. Improved climate risk simulations for rice in arid environments.

    Directory of Open Access Journals (Sweden)

    Pepijn A J van Oort

    Full Text Available We integrated recent research on cardinal temperatures for phenology and early leaf growth, spikelet formation, early morning flowering, transpirational cooling, and heat- and cold-induced sterility into an existing to crop growth model ORYZA2000. We compared for an arid environment observed potential yields with yields simulated with default ORYZA2000, with modified subversions of ORYZA2000 and with ORYZA_S, a model developed for the region of interest in the 1990s. Rice variety 'IR64' was sown monthly 15-times in a row in two locations in Senegal. The Senegal River Valley is located in the Sahel, near the Sahara desert with extreme temperatures during day and night. The existing subroutines underestimated cold stress and overestimated heat stress. Forcing the model to use observed spikelet number and phenology and replacing the existing heat and cold subroutines improved accuracy of yield simulation from EF = -0.32 to EF =0.70 (EF is modelling efficiency. The main causes of improved accuracy were that the new model subversions take into account transpirational cooling (which is high in arid environments and early morning flowering for heat sterility, and minimum rather than average temperature for cold sterility. Simulations were less accurate when also spikelet number and phenology were simulated. Model efficiency was 0.14 with new heat and cold routines and improved to 0.48 when using new cardinal temperatures for phenology and early leaf growth. The new adapted subversion of ORYZA2000 offers a powerful analytic tool for climate change impact assessment and cropping calendar optimisation in arid regions.

  2. Understanding land administration systems

    DEFF Research Database (Denmark)

    P. Williamson, Ian; Enemark, Stig; Wallace, Judy

    2008-01-01

    in contributing to sustainable development, thirdly the changing nature of ownership and the role of land markets, and lastly a land management vision that promotes land administration in support of sustainable development and spatial enablement of society. We present here the first part of the paper. The second...... part focuses on the changing  role of ownership and the role of land markets, and a land management vision will be published in November issue of Coordinates. Udgivelsesdato: Oktober......This paper introduces basic land administration theory and highlights four key concepts that are fundamental to understanding modern land administration systems - firstly the land management paradigm and its influence on the land administration framework, secondly the role that the cadastre plays...

  3. Landing spot selection for UAV emergency landing

    NARCIS (Netherlands)

    Eendebak, P.T.; Eekeren, A.W.M. van; Hollander, R.J.M. den

    2013-01-01

    We present a robust method for landing zone selection using obstacle detection to be used for UAV emergency landings. The method is simple enough to allow real-time implementation on a UAV system. The method is able to detect objects in the presence of camera movement and motion parallax. Using the

  4. Biogeochemical factors contributing to enhanced carbon storage following afforestation of a semi-arid shrubland

    Directory of Open Access Journals (Sweden)

    J. M. Grünzweig

    2007-07-01

    Full Text Available Ecosystems in dry regions are generally low in productivity and carbon (C storage. We report, however, large increases in C sequestration following afforestation of a semi-arid shrubland with Pinus halepensis trees. Using C and nitrogen (N inventories, based in part on site-specific allometric equations, we measured an increase in the standing ecosystem C stock from 2380 g C m−2 in the shrubland to 5840 g C m−2 in the forest after 35 years, with no significant change in N stocks. The total amount of C produced by the forest was estimated as 6250 g C m−2. Carbon sequestration following afforestation was associated with increased N use efficiency as reflected by an overall increase in C/N ratio from 7.6 in the shrubland to 16.6 in the forest. The C accumulation rate in the forest was particularly high for soil organic C (SOC; increase of 1760 g C m−2 or 50 g C m−2 yr−1, which was associated with the following factors: 1 Analysis of a small 13C signal within this pure C3 system combined with size fractionation of soil organic matter indicated a significant addition of new SOC derived from forest vegetation (68% of total forest SOC and a considerable portion of the old original shrubland SOC (53% still remaining in the forest. 2 A large part of both new and old SOC appeared to be protected from decomposition as about 60% of SOC under both land-use types were in mineral-associated fractions. 3 A short-term decomposition study indicated decreased decomposition of lower-quality litter and SOC in the forest, based on reduced decay rates of up to 90% for forest compared to shrubland litter. 4 Forest soil included a significant component of live and dead roots. Our results showed the considerable potential for C sequestration, particularly in soils, following afforestation in semi-arid regions, which is particularly relevant in light of persistent

  5. Responses of desert, semi-arid grassland and scrub-oak ecosystems to elevated CO2

    Science.gov (United States)

    Luus, Kristina; Walker, Anthony; de Kauwe, Martin; Hungate, Bruce; Megonigal, J. Patrick; Lu, Meng; Fenstermaker, Lynn; Nowak, Robert; Morgan, Jack; Medlyn, Belinda; Norby, Richard; Zaehle, Sönke

    2014-05-01

    We compared observations from free air CO2 enrichment (FACE) experiments at dry (desert, semi-arid grassland and scrub-oak) sites, to predictions from a suite of ecosystem models with differing complexity, ranging from a parsimonious forest growth model (GDAY) to a comprehensive land surface model (OCN). Dry ecosystems have often been predicted to increase in net primary productivity (NPP) and net C uptake over time in response to elevated CO2 (eCO2) because of increased N fixation, and alleviation of drought-stress due to reduced stomatal conductance. However, experiments at the Nevada Desert FACE (NDFF), the semi-arid prairie grassland FACE (PHACE), and the scrub-oak Kennedy Space Center open-top chamber experiment (KSCO), have revealed that dry ecosystems display a more complex biogeochemical response to eCO2. Insights into the processes determining the responses of dry ecosystems to eCO2 were gained by evaluating model estimates against site data, and by dissecting model responses to eCO2. Site level findings at PHACE indicated that eCO2 enabled more rapid C turnover, resulting in a net ecosystem C loss. Conversely, at PHACE, models such as OCN simulated a decrease in N leaching and an increase in NPP because of eCO2, leading to increased C storage. Leaf cover and NPP at KSCO initially increased with eCO2 before declining due to reduced N fixation and increased N leaching. At NDFF, eCO2 only increased plant growth during one abnormally wet year; in subsequent years, soil crust cyanobacteria decreased in abundance, and gains in biomass were not sustained. In OCN simulations at NDFF, eCO2 increased water-use efficiency and NPP in years with average to above-average precipitation. Through examination of the reasons for discrepancies between observed and modeled ecosystem responses to eCO2, processes determining the biogeochemical responses of dry ecosystems to eCO2 were elucidated.

  6. Ecosystem restoration at the Arid-Semiarid Interface in Israel's Northern Negev

    Science.gov (United States)

    Mor-Mussery, Amir; Leu, Stefan; Bar-Kutiel, Pua

    2016-04-01

    The interface between the arid and semi-arid zones in Southern Israel (as elsewhere in the world) is heavily degraded. Thousands of years of overexploitation by wood cutting, farming and grazing have left the area at 10 - 30% of their nominal biological productivity, void of any trees and shrubs, and generally low in biodiversity. Degradation is an ongoing process in Israel's open areas, whereby overgrazing and continuous soil tilling for field crops, and contour trenching for planting of exotic tree species are the main drivers for ongoing soil degradation. The results of those activities are further loss of productivity, soil organic matter and soil nutrients, and massive soil erosion. In the framework of several research projects and a large ecosystem restoration project (http://www.sustainabilitylabs.org/ecosystem-restoration/) we have analyzed in detail the drivers of degradation by field studies accompanied by GIS analyses. Various approaches for soil restoration have been attempted and documented. Fencing of and protection from grazing has a rapid impact on the amount of standing biomass left both in rocky slopes, and degraded loess plains, leading to increased plant biodiversity, and initiating rapid growth in harvester ant activity. This ant activity seems to provide an important positive feedback on enhancing soil fertility and biological productivity, and we postulate a recovery mechanisms whereby enhanced food availability to ants and similar soil dwelling herbivores enhances soil nutrient pools, soil organic matter, soil aeration and soil water infiltration to result in a cycle of ongoing productivity improvements and ecosystem recovery. Alternative, faster and more expensive methods of restoration tested are overlaying of degraded soils using compost or manure, a method immediately restoring 5 - 10 fold higher biological productivity, which was being maintained for at least 10 years and appears permanent unless renewed degradation should occur. We

  7. Analysis of aerosol-cloud-interactions over semi-arid and arid subtropical land regions from three different satellite datasets (MODIS, AATSR/ENVISAT, IASI)

    OpenAIRE

    Klüser, Lars

    2014-01-01

    Indirect aerosol effects, i.e. the change of cloud physical properties by aerosol interactions, have been identified as one of the largest uncertainties in the current understanding of the climate system. Despite the uncertainties of the representations of aerosol-cloud interactions in current climate projections, they have large impact on the climate system itself – in terms of the radiation balance, but also in terms of precipitation, and thus vegetation cover, and re-distribution of water ...

  8. LandSat-Based Land Use-Land Cover (Raster)

    Data.gov (United States)

    Minnesota Department of Natural Resources — Raster-based land cover data set derived from 30 meter resolution Thematic Mapper satellite imagery. Classification is divided into 16 classes with source imagery...

  9. LandSat-Based Land Use-Land Cover (Vector)

    Data.gov (United States)

    Minnesota Department of Natural Resources — Vector-based land cover data set derived from classified 30 meter resolution Thematic Mapper satellite imagery. Classification is divided into 16 classes with source...

  10. Water balance modelling in a semi-arid environment with limited in-situ data: remote sensing coupled with satellite gravimetry, Lake Manyara, East African Rift, Tanzania

    Directory of Open Access Journals (Sweden)

    D. Deus

    2011-09-01

    Full Text Available Accurate and up to date information on the status and trends of water balance is needed to develop strategies for conservation and the sustainable management of water resources. The purpose of this research is to estimate water balance in a semi-arid environment with limited in-situ data by using a remote sensing approach. We focus on the Lake Manyara catchment, located within the East African Rift of northern Tanzania. We use remote sensing and a semi-distributed hydrological model to study the spatial and temporal variability of water balance parameters within Manyara catchment. Satellite gravimetry GRACE data is used to verify the trend of the water balance result. The results show high spatial and temporal variations and characteristics of a semi-arid climate with high evaporation and low rainfall. We observe that the Lake Manyara water balance and GRACE equivalent water depth show comparable trends a decrease after 2002 followed by a sharp increase in 2006–2007. Despite the small size of Lake Manyara, GRACE data are useful and show great potential for hydrological research on smaller un-gauged lakes and catchments in semi-arid environments. Our modelling confirms the importance of the 2006–2007 Indian Ocean Dipole fluctuation in replenishing the groundwater reservoirs of East Africa. The water balance information can be used for further analysis of lake variations in relation to soil erosion, climate and land cover/land use change as well as different lake management and conservation scenarios. We demonstrate that water balance modelling can be performed accurately using remote sensing data even in complex climatic settings.

  11. Sahra integrated modeling approach to address water resources management in semi-arid river basins

    Energy Technology Data Exchange (ETDEWEB)

    Springer, E. P.; Gupta, Hoshin V. (Hoshin Vijai),; Brookshire, David S.; Liu, Y. (Yuqiong)

    2004-01-01

    Water resources decisions in the 21Sf Century that will affect allocation of water for economic and environmental will rely on simulations from integrated models of river basins. These models will not only couple natural systems such as surface and ground waters, but will include economic components that can assist in model assessments of river basins and bring the social dimension to the decision process. The National Science Foundation Science and Technology Center for Sustainability of semi-Arid Hydrology and Riparian Areas (SAHRA) has been developing integrated models to assess impacts of climate variability and land use change on water resources in semi-arid river basins. The objectives of this paper are to describe the SAHRA integrated modeling approach and to describe the linkage between social and natural sciences in these models. Water resources issues that arise from climate variability or land use change may require different resolution models to answer different questions. For example, a question related to streamflow may not need a high-resolution model whereas a question concerning the source and nature of a pollutant will. SAHRA has taken a multiresolution approach to integrated model development because one cannot anticipate the questions in advance, and the computational and data resources may not always be available or needed for the issue to be addressed. The coarsest resolution model is based on dynamic simulation of subwatersheds or river reaches. This model resolution has the advantage of simplicity and social factors are readily incorporated. Users can readily take this model (and they have) and examine the effects of various management strategies such as increased cost of water. The medium resolution model is grid based and uses variable grid cells of 1-12 km. The surface hydrology is more physically based using basic equations for energy and water balance terms, and modules are being incorporated that will simulate engineering components

  12. Do protected areas networks ensure the supply of ecosystem services? Spatial patterns of two nature reserve systems in semi-arid Spain

    DEFF Research Database (Denmark)

    Castro, Antonio J.; Martín-López, Berta; López, Enrique;

    2015-01-01

    Protected areas are essential for conserving biodiversity, and these lands have traditionally been set aside for this purpose alone. However, the increasing global demand for agricultural and forestry commodities creates conflict and tradeoffs between dedicating land for conservation versus food...... that protected areas provide social and economic benefits that can be used to build political support and raise funds for conservation. We analyzed the capability of current protected area networks in the semi-arid region of Spain to provide intermediate regulating services (habitat preservation for threatened...... and groundwater recharge. Our results demonstrate that the integration of systematic analyses of ecosystem services gaps in protected area planning could contribute substantially to safeguarding ecosystem services and biodiversity jointly. However, our study also reveals substantial differences in intermediate...

  13. Understanding the erosion of semi-arid landscapes subject to vegetation change: a combined approach using monitoring, isotope and {sup 1}4c analysis

    Energy Technology Data Exchange (ETDEWEB)

    Brazier, R. E.; Turbull, L.; Bol, R.; Dixon, L.; Wainwright, J.

    2009-07-01

    The degradation of grasslands is a common problem across semi-arid areas worldwide.over the last 150 years much of the south-Western USA has experienced significant land degradation, with desert grasslands becoming dominated by shrubs and concurrent changes in runoff and erosion which are thought to propagate further the process of degradation. Field-based experiments were carried out to determine how runoff and erosion vary at stages over a transition from a black grama (Bouteloua eriopoda) grassland to creosote bush (Larrea tridentata) shrub land at the Sevilleta NWR LTER site in New Mexico. {delta}{sup 1}3 C and {delta}{sup 1}5 N analyses were carried out to investigate the age and potential provenance of eroded sediment. (Author) 4 refs.

  14. Uranium isotopes in carbonate aquifers of arid region setting

    DEFF Research Database (Denmark)

    Alshamsi, Dalal M.; Murad, Ahmed A.; Aldahan, Ala

    2013-01-01

    Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of 238U and 235U in groundwater of four selected locations in the so......Groundwater in arid and semiarid regions is vital resource for many uses and therefore information about concentrations of uranium isotopes among other chemical parameters are necessary. In the study presented here, distribution of 238U and 235U in groundwater of four selected locations...... in the southern Arabian peninsula, namely at two locations within the United Arab Emirates (UAE) and two locations in Oman are discussed. The analyses of the uranium isotopes were performed using ICP-MS and the results indicated a range of concentrations for 235U and 238 U at 3–39 ng L-1 (average: 18 ng L-1......) and 429–5,293 ng L-1 (average: 2,508 ng L-1) respectively. These uranium concentrations are below the higher permissible WHO limit for drinking water and also comparable to averages found in groundwater from similar aquifers in Florida and Tunisia. Negative correlation between rainfall and uranium...

  15. Expansive Soil Properties in a Semi-Arid Region

    Directory of Open Access Journals (Sweden)

    MuawiaA. Dafalla

    2012-11-01

    Full Text Available The expansive soils in semi-arid regions are of great concern to design and geotechnical engineers. Range and variations of geotechnical properties of soils are very useful for appropriate design. Saudi Arabia; a semi arid region attracted the attention of researchers and practicing engineers over the last three decades following the rapid urbanizations in different parts of the country. Advanced testing equipments were made available for this study. The research group conducted joint visits with high officials from different municipality authorities to survey the problem and study the extent of damage to various structures. The areas visited included Al Ghatt, Al Zulfi, Al Hofuf, Um Al Sahik, Al Qatif, Tabuk, Tayma and Al Qaleeba. Single and two storey buildings, boundary walls, pavements and asphalt roads suffered significant damage in many parts of the visited locations. This paper presents the outcome of survey and a general review of previous works carried out for swelling clays in Saudi Arabia. Engineering properties for typical soil formation are presented.

  16. An Evaluation of Unsaturated Flow Models in an Arid Climate

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, J. [Univ. of Nevada, Las Vegas, NV (United States)

    1999-12-01

    The objective of this study was to evaluate the effectiveness of two unsaturated flow models in arid regions. The area selected for the study was the Area 5 Radioactive Waste Management Site (RWMS) at the Nevada Test Site in Nye County, Nevada. The two models selected for this evaluation were HYDRUS-1D [Simunek et al., 1998] and the SHAW model [Flerchinger and Saxton, 1989]. Approximately 5 years of soil-water and atmospheric data collected from an instrumented weighing lysimeter site near the RWMS were used for building the models with actual initial and boundary conditions representative of the site. Physical processes affecting the site and model performance were explored. Model performance was based on a detailed sensitivity analysis and ultimately on storage comparisons. During the process of developing descriptive model input, procedures for converting hydraulic parameters for each model were explored. In addition, the compilation of atmospheric data collected at the site became a useful tool for developing predictive functions for future studies. The final model results were used to evaluate the capacities of the HYDRUS and SHAW models for predicting soil-moisture movement and variable surface phenomena for bare soil conditions in the arid vadose zone. The development of calibrated models along with the atmospheric and soil data collected at the site provide useful information for predicting future site performance at the RWMS.

  17. Lipid accumulation in prokaryotic microorganisms from arid habitats.

    Science.gov (United States)

    Hauschild, Philippa; Röttig, Annika; Madkour, Mohamed H; Al-Ansari, Ahmed M; Almakishah, Naief H; Steinbüchel, Alexander

    2017-03-01

    This review shall provide support for the suitability of arid environments as preferred location to search for unknown lipid-accumulative bacteria. Bacterial lipids are attracting more and more attention as sustainable replacement for mineral oil in fuel and plastic production. The development of prokaryotic microorganisms in arid desert habitats is affected by its harsh living conditions. Drought, nutrient limitation, strong radiation, and extreme temperatures necessitate effective adaption mechanisms. Accumulation of storage lipids as energy reserve and source of metabolic water represents a common adaption in desert animals and presumably in desert bacteria and archaea as well. Comparison of corresponding literature resulted in several bacterial species from desert habitats, which had already been described as lipid-accumulative elsewhere. Based on the gathered information, literature on microbial communities in hot desert, cold desert, and humid soil were analyzed on its content of lipid-accumulative bacteria. With more than 50% of the total community size in single studies, hot deserts appear to be more favorable for lipid-accumulative species then humid soil (≤20%) and cold deserts (≤17%). Low bacterial lipid accumulation in cold deserts is assumed to result from the influence of low temperatures on fatty acids and the increased necessity of permanent adaption methods.

  18. Soil microbial responses to nitrogen addition in arid ecosystems

    Directory of Open Access Journals (Sweden)

    Robert L Sinsabaugh

    2015-08-01

    Full Text Available The N cycle of arid ecosystems is influenced by low soil organic matter, high soil pH and extremes in water potential and temperature that lead to open canopies and development of biological soil crusts (biocrusts. We investigated the effects of N amendment on soil microbial dynamics in a Larrea tridentata-Ambrosia dumosa shrubland site in southern Nevada USA. Sites were fertilized with a NO3-NH4 mix at 0, 7, and 15 kg ha-1 yr-1 from March 2012 to March 2013. In March 2013, biocrust (0-0.5 cm and bulk soils (0-10 cm were collected beneath Ambrosia canopies and in the interspaces between plants. Biomass responses were assessed as bacterial and fungal SSU rRNA gene copy number and chlorophyll a concentration. Metabolic responses were measured by five ecoenzyme activities (EEA and rates of N transformation. By most measures, nutrient availability, microbial biomass and process rates were greater in soils beneath the shrub canopy compared to the interspace between plants, and greater in the surface biocrust horizon compared to the deeper 10 cm soil profile. Most measures responded positively to experimental N addition. Effect sizes were generally greater for bulk soil than biocrust. Results were incorporated into a meta-analysis of arid ecosystem responses to N.

  19. A methodology to assess and evaluate rainwater harvesting techniques in (semi-) arid regions

    NARCIS (Netherlands)

    Adham, Ammar; Riksen, Michel; Ouessar, Mohamed; Ritsema, Coen J.

    2016-01-01

    Arid and semi-arid regions around the world face water scarcity problems due to lack of precipitation and unpredictable rainfall patterns. For thousands of years, rainwater harvesting (RWH) techniques have been applied to cope with water scarcity. Researchers have used many different methodologie

  20. Resource flows, crops and soil fertility management in smallholder farming systems in semi-arid Zimbabwe

    NARCIS (Netherlands)

    Ncube, B.; Twomlow, S.J.; Dimes, J.P.; Wijk, van M.T.; Giller, K.E.

    2009-01-01

    Poor soil fertility and erratic rains are major constraints to crop production in semi-arid environments. In the smallholder farming systems of sub-Saharan Africa, these constraints are manifested in frequent crop failures and endemic food insecurity. We characterized a semi-arid smallholder farming

  1. Differences in the ARID-1 alpha expressions in squamous and adenosquamous carcinomas of uterine cervix.

    Science.gov (United States)

    Solakoglu Kahraman, Dudu; Diniz, Gulden; Sayhan, Sevil; Ayaz, Duygu; Uncel, Melek; Karadeniz, Tugba; Akman, Tulay; Ozdemir, Aykut

    2015-10-01

    AT-rich interactive domain 1A (ARID1A) is a tumor suppressor gene involved in chromatin remodeling which encodes ARID1A (BAF250a) protein. Recent studies have shown the loss of ARID1A expression in several types of tumors. This retrospective study was designed to evaluate the differences in tissue expressions of ARID1A in a spectrum of cervical neoplasms. Cervical intraepithelial neoplasms, invasive squamous or adenosquamous carcinomas were identified in 100 patients recently diagnosed as cervical neoplasms based on pathology databases. In this series, there were 29 low- and 29 high-grade cervical intraepithelial neoplasms, 27 squamous cell carcinomas, and 15 adenosquamous carcinomas. Mean age of the patients was 47.8 ± 13 years (20-80 years). It was determined that the expression of ARID1A was statistically significantly down-regulated in adenosquamous carcinomas when compared with non-invasive or invasive squamous cell carcinomas (p = 0.015). Lower levels of the ARID1A expression were detected in cases with adenosquamous carcinomas (60%), low- or high-grade squamous intraepithelial lesion (SIL) (31%), and squamous cell carcinomas (18.5%). Our findings have demonstrated the presence of a correlation between ARID1A expression and adenomatous differentiation of uterine squamous cell carcinomas. Therefore, ARID1A gene may suggestively have a role in the pathogenesis of cervical adenosquamous carcinomas.

  2. Is aridity a high-order control on the hydro-geomorphic response of burned landscapes?

    Science.gov (United States)

    Sheridan, Gary; Van der Sant, Rene; Nyman, Petter; Lane, Patrick

    2015-04-01

    Fire results in hydro-geomorphic changes that are spatially variable and difficult to predict. In this study we compile 294 infiltration measurements, ten other soil, catchment runoff and erosion datasets, and a year of new data from 15 natural runoff plots across an aridity gradient from the eastern Victorian uplands in SE Australia. The results show that aridity (a function of the long term mean precipitation and net radiation) is associated with low post-fire infiltration capacities, increasing the chance of surface runoff, and strongly increasing the chance of debris flows. Runoff plots from the wettest site (aridity = 1.1) had an average runoff ratio of 0.3% compared with 33.6% for the most arid sites (aridity = 2.4). Post-fire debris flows were only observed in the more arid locations within the Victorian uplands, and resulted in erosion rates more than two orders of magnitude greater than non-debris flow processes. We therefore argue that in south eastern Australia aridity is a high-order control on the magnitude of post-wildfire hydro-geomorphic processes. The results from this Australian study may also help to provide insight into the landscape controls on post fire debris flows elsewhere. Aridity is a landscape-scale parameter that is mappable at a high resolution and therefore is a useful predictor of the spatial variability of the magnitude of post-fire hydro-geomorphic responses.

  3. Analysis and evaluation of tillage on an alfisol ina semi-arid tropical region of India

    NARCIS (Netherlands)

    Klaij, M.C.

    1983-01-01

    Tillage field experiments were conducted on Alfisols in a semi-arid tropical environment in India. The research was conducted within the framework of the Farming Systems Research Program of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).To put the experiments into per

  4. Review and Synopsis of Natural and Human Controls on Fluvial Channel Processes in the Arid West

    Science.gov (United States)

    2007-09-01

    and other wet saline and alkaline soils: Problems identifying aquic conditions and hydric soils. In Aquic Conditions and Hydric Soils: The Problem...of-the-art of hydrology and hydrogeology in the arid and semi-arid areas of Africa. p. 255–266. Proceedings of the Sahel Forum 1989. Ouagadougou

  5. An overview of biodegradation of LNAPLs in coastal (semi)-arid environment

    NARCIS (Netherlands)

    Yadav, B.K.; Hassanizadeh, S.M.

    2011-01-01

    Contamination of soil and water due to the release of light non-aqueous phase liquids (LNAPLs) is a ubiquitous problem. The problem is more severe in arid and semi-arid coastal regions where most of the petroleum production and related refinery industries are located. Biological treatment of these o

  6. Biophysical-and socioeconomic aspects of land degradation in the Guadalentin (SE-Spain): towards understanding and effective soil conservation

    Energy Technology Data Exchange (ETDEWEB)

    Vente, J. de; Sole-Benet, A.; Boix-Fayos, C.; Nainggolan, D.; Romero-Diaz, A.

    2009-07-01

    Desertification and land degradation have been widely studied in the Guadalentin basin (SE Spain) through various national and international research projects. Most important identified degradation types are due to soil erosion, soil surface crusting, aridity, soil organic matter decline and salinisation. On the one hand, political and socioeconomic drivers have caused important land use and management changes, which have formed an important driver for further land degradation. On the other hand, soil conservation practice were initiated by the government and by individual land users, although there is very limited knowledge on their effectiveness. the objective of this work is to provide and overview of previous studies that addressed land degradation in the Guadalentin and to present an integrated synthesis of the main biophysical and socioeconomic factors identifies in these studies as being responsible for land degradation, with a focus on feasible soil conservation strategies. (Author) 18 refs.

  7. Study on the oasis corridor landscape in the arid regions based on RS and GIS methods--application of Jinta Oasis, China

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The study on the oasis corridor landscape is a new hotspot in the ecological environment research in the arid regions.In oasis, maincorridor landscape types include river, ditch, shelterbelt and road.This paper introduces the basic ecological effects of the corridor landscapeon the transporting mass and energy and obstructing desert landscape expansion and incursion.Using Geographic Information System(GIS), wehave researched the corridor distribution and its spatial relationship with other landscape types in the Jinta Oasis.Based on the dynamicallymonitoring on the landscape pattern change of the Jinta Oasis during the latter 10 years by using Remote Sensing(RS) and GIS, the drivingfunctions of the corridors on this change have been analyzed in detail.The analysis results showed that all kinds of corridors' characteristics canbe quantified by the indexes such as length and width, ratio of perimeter and area, density and non-heterogeneity.The total corridor length ofJinta Oasis is 1838.5 km and its density is 2.1 km/km2 .The corridor density of the irrigation land, forest and resident area is maximal, whichshows that affection degree of the oasis corridors on them is the most.The improvement of the corridors quality is one of the important drivingfactors on the irrigation land and so on.The organic combination of the RS and GIS technologies and landscape research methods would be aneffective means for the corridor landscape research on arid region oasis.

  8. Land Cover Characterization Program

    Science.gov (United States)

    ,

    1997-01-01

    The U.S. Geological Survey (USGS) has a long heritage of leadership and innovation in land use and land cover mapping. The USGS Anderson system defined the principles for land use and land cover mapping that have been the model both nationally and internationally for more than 20 years. The Land Cover Characterization Program (LCCP) is founded on the premise that the Nation's needs for land cover and land use data are diverse and increasingly sophisticated. The range of projects, programs, and organizations that use land cover data to meet their planning, management, development, and assessment objectives has expanded significantly. The reasons for this are numerous, and include the improved capabilities provided by geographic information systems, better and more data-intensive analytic models, and increasing requirements for improved information for decision making. The overall goals of the LCCP are to:

  9. Land Type Inventory

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is an inventory of the number of acres of various land types found at Kenai National Moose Range. Forestlands are the predominant land type, followed by tundra,...

  10. US State Submerged Lands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Submerged Lands Act (43 U.S.C. Section 1301 et seq.) grants coastal states title to natural resources located within their coastal submerged lands and navigable...

  11. Focus on land reclamation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-04-01

    Various aspects of land reclamation, i.e. returning disturbed land to a state where, at minimum, it is at least capable of supporting the same kinds of land uses as before the disturbance, are discussed. Activities which disturb the land such as surface mining of coal, surface mining and extraction of oil sands, drilling for oil and natural gas, waste disposal sites, including sanitary landfills, clearing timber for forestry, excavating for pipelines and transportation are described, along with land reclamation legislation in Alberta, and indications of future developments in land reclamation research, legislation and regulation. Practical guidelines for individuals are provided on how they might contribute to land reclamation through judicious and informed consumerism, and through practicing good land management, inclusive of reduced use of herbicides, composting of household wastes, and planting of native species or ground cover in place of traditional lawns.

  12. The land management perspective

    DEFF Research Database (Denmark)

    Enemark, Stig

    2006-01-01

    paradigm. In many countries, and especially developing countries and countries in transition, the national capacity to manage land rights, restrictions and responsibilities is not well developed in terms of mature institutions and the necessary human resources and skills. In this regard, the capacity......Land management is the process by which the resources of land are put into good effect. Land management encompasses all activities associated with the management of land that are required to achieve sustainable development. The concept of land includes properties and natural resources and thereby...... encompasses the total natural and built environment. Land Administration Systems (LAS) are institutional frameworks complicated by the tasks they must perform, by national cultural, political and judicial settings, and by technology. This paper facilitates an overall understanding of the land management...

  13. Apcocynum Pictum and Sustainable Agriculture Along the Tarim River In Arid Northwest, China

    Science.gov (United States)

    Aihemaitijiang, R.

    2014-12-01

    Water scarcity and population increase have been a major limiting factor in oasis development along the Tarim River in Xinjiang, Northwest China which has very continental and dry climate, and all the agriculture and livelihoods depend on glacier melt water from Tarim River. Due to vast land reclamation along the Tarim River to grow cotton, native plant species are facing a severe competition for water, which is essential for their survival. Decreasing river runoff and inefficient water use practices by agriculture and industry has exacerbated already serious situation even worse. In addition, a large influx of migrant famers from Eastern China is being settled in this region to cultivate new agricultural lands that consumed even more water. Under those conditions, the natural riparian vegetation and the irrigation agriculture, especially along the lower reaches, suffers water shortage leading the degradation and economic losses, respectively. Along with the enlargement of irrigation area and periods of water shortage, soil salinization has become a major concern for farmers in the area. Alternative cash crops are much needed to reduce water use, so both native vegetation and human demand for water would be fulfilled. We hypothesized Apocynum Pictum, perennial herb species with multiple uses as potential substitute. Multidisciplinary approach is being used in this study to investigate three related issues to offer a basis for Apocynum's role in sustainable agriculture, such as Biomass production of Apocynum; Water budget of Apocynum; and Economic utilization of Apocynum. A.Pictum is perennial plant distributed in Central Asia and China, which its roots are perennial, while the stems die every year. Thus, A.pictum grow under the arid climate of Central Asia and provide utilization options without irrigation. We initially estimate water requirement for this plant is much less than cotton. In order to validate our hypothesis, we have measured water consumption of the

  14. Impact of rhizobial populations and their host legumes on microbial activity in soils of arid regions in Tunisia

    Energy Technology Data Exchange (ETDEWEB)

    Fterich, A.; Mahdhi, M.; Mars, M.

    2009-07-01

    Nitrogen fixing legumes and their microsymbionts are a fundamental contributor to soil fertility and prevent their degradation in arid and semi arid ecosystems. In Tunisia, few data are available on the contribution of these legumes in microbial activity in the arid soil. In this objective, a study was undertaken on five leguminous species from different arid regions to evaluate their ability to regenerate microbiological processes of the soil: Genista saharea, Genista microcephala, Acacia tortilis sspr raddiana, Retama raetam and Prosopis stephaniana. (Author)

  15. Biomarker evidence for increasing aridity in south-central India over the Holocene

    Science.gov (United States)

    Sarkar, S.; Wilkes, H.; Prasad, S.; Brauer, A.; Basavaiah, N.; Strecker, M. R.; Sachse, D.

    2012-12-01

    Summer monsoonal rainfall has played an important role in the development and sustenance of the largely agro-based economy in the Indian subcontinent in the recent past. A better understanding of past variations in monsoonal rainfall can therefore lead to an assessment of its potential impact on early human societies. However, our knowledge of spatiotemporal patterns of past monsoon strength, as inferred from proxy records, is limited due to the lack of high-resolution paleo-hydrological records from continental archives. Here, we reconstruct centennial-scale hydrological variability associated with changes in the intensity of the Indian Summer Monsoon based on a record of lipid biomarker abundances and compound-specific stable isotopic composition of a 10-m-long sediment core from saline-alkaline Lonar Lake, situated in the core 'monsoon zone' of south-central India. We identified three periods of distinct hydrology over the Holocene in south-central India. The period between 10.4 and 6.5 ka BP was characterized by a relatively high abundance of land-plant biomarkers, such as long-chain n-alkanes. The composition of these leaf-wax n-alkanes (weighted average of concentration of different chain-length n-alkanes, expressed as the ACL index) and their negative δ13C (-30‰ to -33 ‰) indicate the dominance of woody C3 vegetation in the catchment, and negative δD (-170‰ to -175‰) values argue for a wet period due to an intensified monsoon. Rapid fluctuations in abundance of both terrestrial and aquatic biomarkers between 6.5 and 4 ka BP indicate an unstable lake ecosystem, culminating in a transition to arid conditions. Higher ACL values and a pronounced shift to more positive δ13C values (up to -22‰) of leaf-wax n-alkanes over this period indicate a change of dominant vegetation to C4 grasses. Along with a 40‰ increase in leaf wax n-alkane δD values, which likely resulted from less rainfall and/or higher plant evapotranspiration, we interpret this period

  16. Analyses of environmental impacts of underground coal mining in an arid region using remote sensing and GIS

    Institute of Scientific and Technical Information of China (English)

    BIAN Zheng-fu; ZHANG Hai-xia; LEI Shao-gang

    2011-01-01

    The influences of coal mining in an arid environment on vegetation coverage,land-use change,desertification,soil and water loss were discussed.A series of available TM/ETM+ images with no cloud cover from July/August in different years (1990,1995,2000 and 2005)were used to analyze the change in various land environmental factors over time.The results show that while mining activity initially had a marked adverse impact on the environment,mine rehabilitation measures have also subsequently played a great role in improving vegetation cover and controlling land desertification and loss of water and soil.The effect of coal mining on vegetation cover is dependent upon the soil type and natural indigenous flora.Results of this investigation imply that mining activity has a greater effect on the vegetation of loess areas than at sandy sites.Although local vegetation coverage was improved by planting in the mining area,the total area of land affected by desertification still increased from 26.81% in 1990 when large-scale mine construction was introduced,to 46.79% in 1995.With continuous efforts at rehabilitation,the vegetation cover in the Shendong coal mining area was increasing,and loss of water and soil were effectively controlled since 1995.Subsequently,the total area of extreme desertification decreased to 23.24% in 2000 and further to 18.68% in 2005.The total area affected by severe loss of water and soil also decreased since the early 1990's(70.61% in 1990,71.43% in 1995),to 43.64% in 2000 and 34.93% in 2005,respectively.

  17. Understanding land administration systems

    DEFF Research Database (Denmark)

    P. Williamson, Ian; Enemark, Stig; Wallace, Judy

    2008-01-01

    This paper introduces basic land administration theory and highlights four key concepts that are fundamental to understanding modern land administration systems. Readers may recall the first part of the paper in October issue of Coordinates. Here is the concluding part that focuses on the changing...... role of ownership and the role of land markets. Udgivelsesdato: November...

  18. Spatial and temporal estimation of soil loss for the sustainable management of a wet semi-arid watershed cluster.

    Science.gov (United States)

    Rejani, R; Rao, K V; Osman, M; Srinivasa Rao, Ch; Reddy, K Sammi; Chary, G R; Pushpanjali; Samuel, Josily

    2016-03-01

    The ungauged wet semi-arid watershed cluster, Seethagondi, lies in the Adilabad district of Telangana in India and is prone to severe erosion and water scarcity. The runoff and soil loss data at watershed, catchment, and field level are necessary for planning soil and water conservation interventions. In this study, an attempt was made to develop a spatial soil loss estimation model for Seethagondi cluster using RUSLE coupled with ARCGIS and was used to estimate the soil loss spatially and temporally. The daily rainfall data of Aphrodite for the period from 1951 to 2007 was used, and the annual rainfall varied from 508 to 1351 mm with a mean annual rainfall of 950 mm and a mean erosivity of 6789 MJ mm ha(-1) h(-1) year(-1). Considerable variation in land use land cover especially in crop land and fallow land was observed during normal and drought years, and corresponding variation in the erosivity, C factor, and soil loss was also noted. The mean value of C factor derived from NDVI for crop land was 0.42 and 0.22 in normal year and drought years, respectively. The topography is undulating and major portion of the cluster has slope less than 10°, and 85.3% of the cluster has soil loss below 20 t ha(-1) year(-1). The soil loss from crop land varied from 2.9 to 3.6 t ha(-1) year(-1) in low rainfall years to 31.8 to 34.7 t ha(-1) year(-1) in high rainfall years with a mean annual soil loss of 12.2 t ha(-1) year(-1). The soil loss from crop land was higher in the month of August with an annual soil loss of 13.1 and 2.9 t ha(-1) year(-1) in normal and drought year, respectively. Based on the soil loss in a normal year, the interventions recommended for 85.3% of area of the watershed includes agronomic measures such as contour cultivation, graded bunds, strip cropping, mixed cropping, crop rotations, mulching, summer plowing, vegetative bunds, agri-horticultural system, and management practices such as broad bed furrow, raised sunken beds, and harvesting available water

  19. Modelling land use change in the Ganga basin

    Science.gov (United States)

    Moulds, Simon; Mijic, Ana; Buytaert, Wouter

    2014-05-01

    Over recent decades the green revolution in India has driven substantial environmental change. Modelling experiments have identified northern India as a "hot spot" of land-atmosphere coupling strength during the boreal summer. However, there is a wide range of sensitivity of atmospheric variables to soil moisture between individual climate models. The lack of a comprehensive land use change dataset to force climate models has been identified as a major contributor to model uncertainty. This work aims to construct a monthly time series dataset of land use change for the period 1966 to 2007 for northern India to improve the quantification of regional hydrometeorological feedbacks. The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board the Aqua and Terra satellites provides near-continuous remotely sensed datasets from 2000 to the present day. However, the quality and availability of satellite products before 2000 is poor. To complete the dataset MODIS images are extrapolated back in time using the Conversion of Land Use and its Effects at Small regional extent (CLUE-S) modelling framework, recoded in the R programming language to overcome limitations of the original interface. Non-spatial estimates of land use area published by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) for the study period, available on an annual, district-wise basis, are used as a direct model input. Land use change is allocated spatially as a function of biophysical and socioeconomic drivers identified using logistic regression. The dataset will provide an essential input to a high-resolution, physically-based land-surface model to generate the lower boundary condition to assess the impact of land use change on regional climate.

  20. Energy Partition From Various Climate Conditions And Land Use Types

    Science.gov (United States)

    Cheng, Chi-Han; Hsu2, Pang-Chi

    2015-04-01

    Investigating how energy partitions and what factors control energy exchange is critical for better understanding the hydrological cycle, boundary layer dynamics, and land -atmosphere coupling. Climate and land use conditions are the two main factors to control energy partitation. However, previous studies discussed energy partition and factors that controlled Bowen ratio (i.e., ratio of sensible heat flux to latent heat flux) in limited land use types and climate conditions. To provide a more comprehensive analysis over various climate and vegetation types, in this study, we studied eleven different land use types in the eight different climate zones within the United State. The results found out that the Mediterranean climate zone with dry summer season, dry arid (desert) climate zone, and the higher latitude area with severe winter would had higher Bowen ratio, lower precipitation and net radiation. In contrast, the humid climate zones had the lower Bowen ratio, higher net radiation and precipitation. Moreover, the higher Bowen ratio usually happened in the winter or early spring seasons. Regarding land conditions, it is found that soil moistures are the key factor to control Bowen ratio in the drier climate areas. Hence, the grassland and closed shrublands sites have higher Bowen ratio than deciduous broadleaf forests and evergreen needle-leaf forests sites' because of shallower root systems that lack access to the full storage of water in the vadose zone. However, in the humid areas, land use factors, such as stomatal resistance and leaf area, would play an important role in changing latent heat and sensible heat. Based on the tight relationships between Bowen ratio and conditions of climate and land use, we suggest that Bowen ratio could be a useful tool for understanding the potential feedbacks of changes in climate and land use to energy partition and exchange.

  1. A global dataset of the extent of irrigated land from 1900 to 2005

    Directory of Open Access Journals (Sweden)

    S. Siebert

    2014-12-01

    Full Text Available Irrigation intensifies land use by increasing crop yield but also impacts water resources. It affects water and energy balances and consequently the microclimate in irrigated regions. Therefore, knowledge of the extent of irrigated land is important for hydrological and crop modelling, global change research, and assessments of resource use and management. Information on the historical evolution of irrigated lands is limited. The new global Historical Irrigation Dataset (HID provides estimates of the temporal development of the area equipped for irrigation (AEI between 1900 and 2005 at 5 arc-minute resolution. We collected subnational irrigation statistics from various sources and found that the global extent of AEI increased from 63 million ha (Mha in 1900 to 112 Mha in 1950 and 306 Mha in 2005. We developed eight gridded versions of time series of AEI by combining subnational irrigation statistics with different data sets on the historical extent of cropland and pasture. Different rules were applied to maximize consistency of the gridded products to subnational irrigation statistics or to historical cropland and pasture data sets. The HID reflects very well the spatial patterns of irrigated land in the western United States as shown on historical maps. Mean aridity on irrigated land increased and river discharge decreased from 1900–1950 whereas aridity decreased from 1950–2005. The dataset and its documentation are made available in an open data repository at https://mygeohub.org/publications/8 (doi:10.13019/M2MW2G.

  2. Land Treatment Digital Library

    Science.gov (United States)

    Pilliod, David S.; Welty, Justin L.

    2013-01-01

    The Land Treatment Digital Library (LTDL) was created by the U.S. Geological Survey to catalog legacy land treatment information on Bureau of Land Management lands in the western United States. The LTDL can be used by federal managers and scientists for compiling information for data-calls, producing maps, generating reports, and conducting analyses at varying spatial and temporal scales. The LTDL currently houses thousands of treatments from BLM lands across 10 states. Users can browse a map to find information on individual treatments, perform more complex queries to identify a set of treatments, and view graphs of treatment summary statistics.

  3. Landing gear noise attenuation

    Science.gov (United States)

    Moe, Jeffrey W. (Inventor); Whitmire, Julia (Inventor); Kwan, Hwa-Wan (Inventor); Abeysinghe, Amal (Inventor)

    2011-01-01

    A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.

  4. Water pulses and biogeochemical cycles in arid and semiarid ecosystems.

    Science.gov (United States)

    Austin, Amy T; Yahdjian, Laura; Stark, John M; Belnap, Jayne; Porporato, Amilcare; Norton, Urszula; Ravetta, Damián A; Schaeffer, Sean M

    2004-10-01

    The episodic nature of water availability in arid and semiarid ecosystems has significant consequences on belowground carbon and nutrient cycling. Pulsed water events directly control belowground processes through soil wet-dry cycles. Rapid soil microbial response to incident moisture availability often results in almost instantaneous C and N mineralization, followed by shifts in C/N of microbially available substrate, and an offset in the balance between nutrient immobilization and mineralization. Nitrogen inputs from biological soil crusts are also highly sensitive to pulsed rain events, and nitrogen losses, particularly gaseous losses due to denitrification and nitrate leaching, are tightly linked to pulses of water availability. The magnitude of the effect of water pulses on carbon and nutrient pools, however, depends on the distribution of resource availability and soil organisms, both of which are strongly affected by the spatial and temporal heterogeneity of vegetation cover, topographic position and soil texture. The 'inverse texture hypothesis' for net primary production in water-limited ecosystems suggests that coarse-textured soils have higher NPP than fine-textured soils in very arid zones due to reduced evaporative losses, while NPP is greater in fine-textured soils in higher rainfall ecosystems due to increased water-holding capacity. With respect to belowground processes, fine-textured soils tend to have higher water-holding capacity and labile C and N pools than coarse-textured soils, and often show a much greater flush of N mineralization. The result of the interaction of texture and pulsed rainfall events suggests a corollary hypothesis for nutrient turnover in arid and semiarid ecosystems with a linear increase of N mineralization in coarse-textured soils, but a saturating response for fine-textured soils due to the importance of soil C and N pools. Seasonal distribution of water pulses can lead to the accumulation of mineral N in the dry season

  5. Soil microbial responses to nitrogen addition in arid ecosystems.

    Science.gov (United States)

    Sinsabaugh, Robert L; Belnap, Jayne; Rudgers, Jennifer; Kuske, Cheryl R; Martinez, Noelle; Sandquist, Darren

    2015-01-01

    The N cycle of arid ecosystems is influenced by low soil organic matter, high soil pH, and extremes in water potential and temperature that lead to open canopies and development of biological soil crusts (biocrusts). We investigated the effects of N amendment on soil microbial dynamics in a Larrea tridentata-Ambrosia dumosa shrubland site in southern Nevada USA. Sites were fertilized with a NO3-NH4 mix at 0, 7, and 15 kg N ha(-1) y(-1) from March 2012 to March 2013. In March 2013, biocrust (0-0.5 cm) and bulk soils (0-10 cm) were collected beneath Ambrosia canopies and in the interspaces between plants. Biomass responses were assessed as bacterial and fungal SSU rRNA gene copy number and chlorophyll a concentration. Metabolic responses were measured by five ecoenzyme activities and rates of N transformation. By most measures, nutrient availability, microbial biomass, and process rates were greater in soils beneath the shrub canopy compared to the interspace between plants, and greater in the surface biocrust horizon compared to the deeper 10 cm soil profile. Most measures responded positively to experimental N addition. Effect sizes were generally greater for bulk soil than biocrust. Results were incorporated into a meta-analysis of arid ecosystem responses to N amendment that included data from 14 other studies. Effect sizes were calculated for biomass and metabolic responses. Regressions of effect sizes, calculated for biomass, and metabolic responses, showed similar trends in relation to N application rate and N load (rate × duration). The critical points separating positive from negative treatment effects were 88 kg ha(-1) y(-1) and 159 kg ha(-1), respectively, for biomass, and 70 kg ha(-1) y(-1) and 114 kg ha(-1), respectively, for metabolism. These critical values are comparable to those for microbial biomass, decomposition rates and respiration reported in broader meta-analyses of N amendment effects in mesic ecosystems. However, large effect sizes at low N

  6. Bureau of Land Management Land Grant Boundaries

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — This data has been collected by the U.S. Bureau of Land Management (BLM) in New Mexico at the New Mexico State Office. The initial data source is the statewide...

  7. International Coalition Land Use/Land Cover

    Data.gov (United States)

    Minnesota Department of Natural Resources — This data set is a product of an effort to update Minnesota's 1969 land use inventory. The project was funded in 1989 by the State Legislature per recommendation...

  8. Assessment of land use and land cover change using spatiotemporal analysis of landscape: case study in south of Tehran.

    Science.gov (United States)

    Sabr, Abutaleb; Moeinaddini, Mazaher; Azarnivand, Hossein; Guinot, Benjamin

    2016-12-01

    In the recent years, dust storms originating from local abandoned agricultural lands have increasingly impacted Tehran and Karaj air quality. Designing and implementing mitigation plans are necessary to study land use/land cover change (LUCC). Land use/cover classification is particularly relevant in arid areas. This study aimed to map land use/cover by pixel- and object-based image classification methods, analyse landscape fragmentation and determine the effects of two different classification methods on landscape metrics. The same sets of ground data were used for both classification methods. Because accuracy of classification plays a key role in better understanding LUCC, both methods were employed. Land use/cover maps of the southwest area of Tehran city for the years 1985, 2000 and 2014 were obtained from Landsat digital images and classified into three categories: built-up, agricultural and barren lands. The results of our LUCC analysis showed that the most important changes in built-up agricultural land categories were observed in zone B (Shahriar, Robat Karim and Eslamshahr) between 1985 and 2014. The landscape metrics obtained for all categories pictured high landscape fragmentation in the study area. Despite no significant difference was evidenced between the two classification methods, the object-based classification led to an overall higher accuracy than using the pixel-based classification. In particular, the accuracy of the built-up category showed a marked increase. In addition, both methods showed similar trends in fragmentation metrics. One of the reasons is that the object-based classification is able to identify buildings, impervious surface and roads in dense urban areas, which produced more accurate maps.

  9. Changing local land systems

    DEFF Research Database (Denmark)

    Friis, Cecilie; Reenberg, Anette; Heinimann, Andreas

    2016-01-01

    . Combining the conceptual lenses of land systems and livelihood approaches, this paper demonstrates how the land use system has changed substantially because of the establishment of the rubber plantation by the company, notably in the linkages between livestock rearing, upland shifting cultivation...... and lowland paddy rice cultivation. The changes go beyond the immediate competition for land caused by the rubber plantation: a penalty scheme introduced by the rubber company for damage to rubber trees caused by browsing animals has led the villagers to abandon livestock rearing, causing a cascade......This paper investigates the direct and cascading land system consequences of a Chinese company's land acquisition for rubber cultivation in northern Laos. Transnational land acquisitions are increasingly acknowledged as an important driver of direct land use conversion with implications for local...

  10. Land desertification and restoration in Middle East and North Africa (MENA) region

    Institute of Scientific and Technical Information of China (English)

    Hassan M.El Shaer

    2015-01-01

    The Middle East and North Africa (MENA) region is characterized by high population growth, degraded and fragile nat-ural ecosystems, and a limited amount of arable lands. It is one of the most water-scarce regions in the world. The region is heterogeneous in terms of the countries' economies, but because it includes some of the richest and some of the poorest countries in the world, regional average economic performance statistics are misleading. The region is mostly semi-arid and arid, with significant areas of extreme aridity. These areas are further challenged by extreme temperatures, frequent drought, land degradation, and desertification. Recent changes in climate patterns, such as prolonged droughts, record temperatures, and increased rainfall irregularity, intensity and distribution, have all further negatively impacted the natural and agro-ecosystems in the region. Such changes have led to increased vulnerability of the people dependent on such re-sources for their livelihood. This article focuses on the impact of land desertification due to climate changes on the pre-vailing natural resources, and discusses several approaches for mitigating or alleviating desertification. It is clear that water shortage is a problem in many countries of this predominantly arid region, and is unlikely to be reduced and may be exacerbated by climate change. Proposed adaptation strategies might include more efficient organization of water supplies, treatment, and delivery systems, and increased use of groundwater. It is necessary to develop alternative production and management systems appropriate to the socioeconomic and environmental conditions in order to prevent further degradation of the prevailing agro-ecosystems and sustain the livelihoods of farmers living in marginal conditions. Grasslands, livestock, and water resources are likely to be most vulnerable to climate change in the region because they are located mostly in marginal areas. Changes in cropping practices

  11. Effect of climate change on the vulnerability of a socio-ecological system in an arid area

    Science.gov (United States)

    Liu, Hai-Long; Willems, Patrick; Bao, An-Ming; Wang, Ling; Chen, Xi

    2016-02-01

    The vulnerability of arid areas threatens ecosystems and human existence. With climate change and increasing human activities, addressing this vulnerability has become an important concern. To support this objective, we present a complex index system to analyze vulnerability at a regional scale with a 1 km × 1 km resolution. Based on the evaluation framework, which includes natural resources, the natural environment and the social economy, the results indicate that an ecosystem in a mountainous area is more vulnerable than it is in a plain. Land desertification will worsen from 2014 to 2099 under the RCP4.5 scenarios and improve slightly under the RCP8.5 and RCP2.6 scenarios, while the suitable land for agriculture increased slightly under the three scenarios. In addition, a regional sensitivity analysis of vulnerability to climate change shows that the improving region and the worsening region will occupy 1.30% and 74.51%, respectively. In view of this, the socio-ecological system will undergo a worsening trend as a whole. Finally, we simplified how to solve the problem of a socio-ecological system in the future. This research method and results would generate new insights with respect to planning for sustainable development and provide a reference for decision-making.

  12. Impact of Direct Soil Moisture and Revised Soil Moisture Index Methods on Hydrologic Predictions in an Arid Climate

    Directory of Open Access Journals (Sweden)

    Milad Jajarmizadeh

    2014-01-01

    Full Text Available The soil and water assessment tool (SWAT is a physically based model that is used extensively to simulate hydrologic processes in a wide range of climates around the world. SWAT uses spatial hydrometeorological data to simulate runoff through the computation of a retention curve number. The objective of the present study was to compare the performance of two approaches used for the calculation of curve numbers in SWAT, that is, the Revised Soil Moisture Index (SMI, which is based on previous meteorological conditions, and the Soil Moisture Condition II (SMCII, which is based on soil features for the prediction of flow. The results showed that the sensitive parameters for the SMI method are land-use and land-cover features. However, for the SMCII method, the soil and the channel are the sensitive parameters. The performances of the SMI and SMCII methods were analyzed using various indices. We concluded that the fair performance of the SMI method in an arid region may be due to the inherent characteristics of the method since it relies mostly on previous meteorological conditions and does not account for the soil features of the catchment.

  13. Effects of adding water on seasonal variation of soil nitrogen availability under sandy grasslands in semi-arid region

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiao-xing; YU Zhan-yuan; QIAN Wei; XU Da-yong; AI Gui-yan

    2007-01-01

    Water is usally thought of a limiting factor for the restoration of semi-arid ecosystem. In the growing season of 2006, a study was conducted to determine the effects of modeling precipitation on seasonal patterns in concentrations of soil-available nitrogen and to describe the seasonal patterns in soil nitrogen availability and seasonal variation in the rates of net nitrogen mineralization of topsoil at Daqinggou ecological station in Keerqin sand lands, Inner Mongolia Autonomous Region, China. Manipulation of water (80 mm) was designed to be added to experiment plots of sandy grasslands in dry season. Water addition (W) treatment and control (CK) treatment were separately taken in six replications and randomly assigned in 12 plots (4 m×4 m for each) with 2-m buffers betweens. Results showed that the content of soil inorganic nitrogen and net nitrogen mineralization rate were not affected by adding water in sandy grassland of Keerqin sand lands. Net nitrogen mineralization rates ranged from 0.5 μg·g-1·month-1 to 4 μg·g-1·month-1. The highest values of soil inorganic nitrogen and net nitrogen mineralization occurred on October 15 in control plots. The seasonal changes of soil inorganic nitrogen contents exhibited "V" shape pattern that was related to seasonal patterns of soil ammonium-N (ascending trend) and nitrate-N transformation (descending trend).

  14. Applications of Soil Series in Sustainable Land Use of Oasis Farmlands

    Institute of Scientific and Technical Information of China (English)

    QI Shan-zhong; XIAO Hong-lang; LUO Fang

    2005-01-01

    The issue of agricultural land sustainability is important to every part of the world, especially in the developing countries. Based on the data collected by field investigation and laboratory analysis as well as soil classification theory, the authors discuss the applications of soil series in the arid northwestern China. On the one hand, the application in the layout of rational agricultural of oasis farmlands: (1) two soil series,namely,Lanjiabao (main) and Nijiaxiaying, belong to the moderate and extremely arid region in the study area; accordingly, the layout of crops is the spring wheat and maize (main) and winter wheat;(2) Nijiaxiaying (main) and Lanjiabao, however, fall into the warm-cold and extremely arid region, where the winter wheat (main) and spring wheat grow; and (3) the Shangfusi is part of the warm chilly-arid region, which is used as seasonal pastureland. On the other hand, the application on the soil quality of oasis farmlands, the results indicating that among all soil series, the content of N is very low, however, the content of K is abundant, and the content of P is greatly scarce.

  15. Carbon uptake and change in net primary productivity of oasis-desert ecosystem in arid western China with remote sensing technique%干旱生态系统净初级生产力估算及变化探测

    Institute of Scientific and Technical Information of China (English)

    张杰; 潘晓玲; 高志强

    2006-01-01

    Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure.According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV), bare soil and water are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy funation structure of arid land cover in order to avoid the differentiation of regional vegetation system and the disturbance of environmental background. We developed a modified production efficiency model NPP-PEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. This model refer to the GLO-PEM and CASA model was driven with remotely sensed observations, and calculates not just the conversion efficiency of absorbed photosynthetically active radiation but also the carbon fluxes that determine net primary productivity (NPP). We apply and validate the model in the Kaxger and Yarkant river basins in arid western China. The NPP of the study area in 1992 and 1998 was estimated based on the NPP-PEM model. The results show that the improved PEM model, considering the photosynthetical activation of heterogeneous functional vegetation, is in good agreement with field measurements and the existing literature. An accurate agreement (R2= 0.85, P<0.001) between the estimates and the ground-based measurement was obtained. The spatial distribution of mountain-oasis-desert ecosystem shows an obvious heterogeneous carbon uptake. The results are applicable to add ecosystem studies ranging from characterizing carbon cycle, carbon flux over arid areas to monitoring change in mountain-oasis-desert productivity, stress and management.

  16. Antibacterial and Antifungal Potential of some Arid Zone Plants.

    Science.gov (United States)

    Jain, S C; Pancholi, B; Singh, R; Jain, R

    2010-07-01

    Sequential extracts of some medicinally important arid zone plants of Rajasthan, viz. Lepidagathis trinervis Nees., Polycarpea corymbosa Lam. and Sericostoma pauciflorum Stocks. ex Wight. were tested against six bacterial (Gram +ve and Gram -ve) and five fungal strains using agar well diffusion method. Ethyl acetate extract of L. trinervis showed maximum activity against Bacillus subtilis, Enterobactor aerogenes, Pseudomonas aeruginosa, Aspergillus flavus and Trichophyton rubrum (inhibition zone 16.00±0.81, 13.33±0.66, 14.33±1.85, 14.30±0.34 and 23.00±0.00 mm) at varied minimum inhibitory concentrations of 82, 20, 41, 41 and 20 μg/ml, respectively.

  17. Antibacterial and antifungal potential of some arid zone plants

    Directory of Open Access Journals (Sweden)

    Jain S

    2010-01-01

    Full Text Available Sequential extracts of some medicinally important arid zone plants of Rajasthan, viz. Lepidagathis trinervis Nees., Polycarpea corymbosa Lam. and Sericostoma pauciflorum Stocks. ex Wight. were tested against six bacterial (Gram +ve and Gram -ve and five fungal strains using agar well diffusion method. Ethyl acetate extract of L. trinervis showed maximum activity against Bacillus subtilis, Enterobactor aerogenes, Pseudomonas aeruginosa, Aspergillus flavus and Trichophyton rubrum (inhibition zone 16.00±0.81, 13.33±0.66, 14.33±1.85, 14.30±0.34 and 23.00±0.00 mm at varied minimum inhibitory concentrations of 82, 20, 41, 41 and 20 μg/ml, respectively.

  18. Dung of Mammuthus in the arid Southwest, North America

    Science.gov (United States)

    mead, Jim I.; Agenbroad, Larry D.; Davis, Owen K.; Martin, Paul S.

    1986-01-01

    The discovery of a unique organic deposit in a dry cave on the Colorado Plateau, southern Utah, permits the first comparison of the physical characteristics and the diet of the dung of the extinct mammoths from the arid Southwest, North America, with that of mammoths from Siberia and northern China, the only other known locations of such remains. The deposit buried beneath sand and rockfall is composed primarily of mammoth dung, estimated at over 300 m 3. Radiocarbon dates on dung boluses indicate that the mammoths frequented the cave between approximately 14,700 and 11,000 yr B.P. (the range of ages at 2σ). The desiccated boluses, measuring approximately 230 × 170 × 85 mm, are nearly identical in size to dung from extant elephants. The largest contents in the dung are stalks measuring 60 × 4.5 mm. Grasses and sedges dominated the diet, although woody species were commonly eaten.

  19. Passive options for solar cooling of buildings in arid areas

    Energy Technology Data Exchange (ETDEWEB)

    Amer, Emad H. [Department of Mechanical Power Engineering, Faculty of Engineering, Menofiya University, Gamal Abdul Nasser St., Shebin El-kom, Menofiya (Egypt)

    2006-07-15

    The major heat load of buildings and workshops, made of metal structures, is the solar energy supplied through the roof. Several passive modifications have been introduced to the roof in order to reduce the temperature of indoor air in arid areas. An experimental investigation, employing passive modifications, has been carried out to study the reduction in air temperature. The results show that the inside air temperature falls to within 6 and 3{sup o}C, respectively, from the ambient temperature when the ceiling is painted white, or provided with a layer of thermal insulation. Using evaporative cooling or a solar chimney leads to an inside temperature within 1{sup o}C of the ambient temperature. (author)

  20. Performance of pearl millet hybrids under arid conditions

    Directory of Open Access Journals (Sweden)

    V.K. Manga, and Arun Kumar

    2011-09-01

    Full Text Available Sixteen male-sterile lines of pearl millet (Pennisetum glaucum (L. R. Br. found promising at CAZRI, Jodhpur were crossed with nine diverse restorers from different sources in this region, in a line x tester fashion to develop 144 hybrid combinations, with the objective to identify suitable A lines, R lines and hybrid combinations for arid Rajasthan. These hybrids were evaluated at three different locations in western Rajasthan (Tinwari, Pali and Jodhpur during the rainy season of 2003. Eighteen promising hybrids based upon their performance over locations during 2003, were again evaluated in larger plots during the rainy season of 2004. Considering grain yield over all the five locations during the two seasons 2003 and 2004, ten high yielding hybrids were identified. Among these hybrids grain yield ranged from 1932 kg/ha to 2293 kg/ha, and flowering time from 43 to 48 days. The highest yielding hybrid was ICMA 96111 x RIB-3135-18 followed by ICMA 98333 x RIB-3135-18, ICMA 98222 x CZI 9621, ICMA 98004 x RIB-3135-18, ICMA 97555 x RIB-3135-18 and ICMA 95555 x H 77/833-2. It was observed that the restorer lines RIB-3135-18, CZI 9621, H77/833-2, CZI 1676-2, MIR 97171 and ICMR 356 gave high yielding hybrids. Similarly male sterile lines, ICMA 98222, ICMA 97555 and ICMA 98004 were involved in promising hybrid combinations. The hybrid ICMA 98222 x CZI 9621, which was one of the top five high yielding hybrids, ranked first in a multilocation trial conducted during the rainy season of 2005, at Jodhpur, Bawal, Durgapura and Bikaner, representing extreme arid conditions. This hybrid again recorded 12.8% and 6.6% higher grain yield over national checks GHB 538 and ICMH 356 respectively in Initial hybrid trial 2007, and was promoted to the Advance Hybrid and Population Trial for Kharif 2008.

  1. Rainfall partitioning by desert shrubs in arid regions

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We measured the rainfall partitioning among throughfall, stemflow, and interception by desert shrubs in an arid region of China, and analyzed the influence of rainfall and canopy characteristics on this partitioning and its ecohydrological effects. The percent-ages of total rainfall accounted for by throughfall, stemflow, and interception ranged from 78.85±2.78 percent to 86.29±5.07 per-cent, from 5.50±3.73 percent to 8.47±4.19 percent, and from 7.54±2.36 percent to 15.95±4.70 percent, respectively, for the four shrubs in our study (Haloxylon ammodendron, Elaeagnus angustifolia, Tamarix ramosissima, and Nitraria sphaerocarpa). Rain-fall was significantly linearly correlated with throughfall, stemflow, and interception (P < 0.0001). The throughfall, stemflow, and interception percentages were logarithmically related to total rainfall (P < 0.01), but were quadratically related to the maximum 1-hour rainfall intensity (P < 0.01). The throughfall and stemflow percentages increased significantly with increasing values of the rainfall characteristics, whereas the interception percentage generally decreased (except for average wind speed, air temperature, and canopy evaporation). Regression analysis suggested that the stemflow percentage increased significantly with increasing crown length, number of branches, and branch angle (R2 = 0.92, P < 0.001). The interception percentage increased significantly with increasing LAI (leaf area index) and crown length, but decreased with increasing branch angle (R2 = 0.96, P < 0.001). The mean funnelling percentages for the four shrubs ranged from 30.27±4.86 percent to 164.37±6.41 percent of the bulk precipitation. Much of the precipitation was funnelled toward the basal area of the stem, confirming that shrub stemflow conserved in deep soil layers may be an available moisture source to support plant survival and growth under arid conditions.

  2. Time Profile of Three Semi-Arid Ecosystems in Africa

    Science.gov (United States)

    Anyamba, A.; Damoah, R.; Small, J. L.; Tucker, C. J.

    2015-12-01

    We examine the spatio-temporal variability of rainfall and satellite derived-vegetation index of three endorheic semi-arid ecosystems in Africa: Lake Chad (in the Sahel region), Okavango and Etosha (Southern Africa) to infer the nature and trends of the variability during the satellite data instrumental record. We utilize African Rainfall Climatology Precipitation Estimates (1983-2014) and Normalized Difference Vegetation Index (NDVI) derived from the Advanced Very High Resolution Radiometer (AVHRR: 1981-2014) and Moderate Resolution Imaging Spectroradiometer (MODIS: 2001:2014) to examine the aspects of the annual cycle and interannual variability using both time series plots and time-space diagrams. With respect to Lake Chad region, the first two decades of the series (1981-2000) show predominantly dryer than long-term average conditions with the periods 1989, 1992 and 1996/1997 as the signature drought periods coinciding with the desiccation of the Sahel region during the 1980s to early 1990s decades. The period 2000 to present is dominated by above average rainfall and NDVI with 2003, 2007 and 2012 being the most pronounced wet/greener years. The southern African ecosystems (Okavango and Etosha) show more or less a similar temporal pattern to that of Lake Chad basin, however, the wet periods are more amplified and persistent especially 2000, 2006, 2010 and 2014, with corresponding above average NDVI departures. The amplified nature of wet and dry periods present in the southern African ecosystem time series are consistent with the El Niño Southern Oscillation teleconnection patterns. Overall these three ecosystems serve as detectable fingerprints of changing climate conditions and ecosystems in these arid regions.

  3. Spatial analysis of the annual and seasonal aridity trends in Extremadura, southwestern Spain

    Science.gov (United States)

    Moral, Francisco J.; Paniagua, Luis L.; Rebollo, Francisco J.; García-Martín, Abelardo

    2016-09-01

    The knowledge of drought (or wetness) conditions is necessary not only for a rational use of water resources but also for explaining landscape and ecology characteristics. An increase in aridity in many areas of the world is expected because of climate change (global warming). With the aim of analysing annual and seasonal aridity trends in Extremadura, southwestern Spain, climate data from 81 locations within the 1951-2010 period were used. After computing the De Martonne aridity index at each location, a geographic information system (GIS) and multivariate geostatistics (regression kriging) were utilised to map this index throughout the region. Later, temporal trends were analysed using the Mann-Kendall test, and the Sen's estimator was utilised to estimate the magnitude of trends. Maps of aridity trends were generated by ordinary kriging algorithm, providing a visualisation of detected annual and seasonal tendencies. An increase in aridity, as the De Martonne aridity index decreased, was apparent during the study period, mainly in the more humid locations of the north of the region. An increase of the seasonal De Martonne aridity index was also found, but it was only statistically significant in some locations in spring and summer, with the highest decreasing rate in the north of Extremadura. Change year detection was achieved using cumulative sum graphs, obtaining that firstly the change point occurred in spring, in the mid-1970s, later in the annual period in the late 1970s and finally in summer at the end of the 1980s.

  4. Arid3b is essential for second heart field cell deployment and heart patterning.

    Science.gov (United States)

    Uribe, Verónica; Badía-Careaga, Claudio; Casanova, Jesús C; Domínguez, Jorge N; de la Pompa, José Luis; Sanz-Ezquerro, Juan José

    2014-11-01

    Arid3b, a member of the conserved ARID family of transcription factors, is essential for mouse embryonic development but its precise roles are poorly understood. Here, we show that Arid3b is expressed in the myocardium of the tubular heart and in second heart field progenitors. Arid3b-deficient embryos show cardiac abnormalities, including a notable shortening of the poles, absence of myocardial differentiation and altered patterning of the atrioventricular canal, which also lacks epithelial-to-mesenchymal transition. Proliferation and death of progenitors as well as early patterning of the heart appear normal. However, DiI labelling of second heart field progenitors revealed a defect in the addition of cells to the heart. RNA microarray analysis uncovered a set of differentially expressed genes in Arid3b-deficient tissues, including Bhlhb2, a regulator of cardiomyocyte differentiation, and Lims2, a gene involved in cell migration. Arid3b is thus required for heart development by regulating the motility and differentiation of heart progenitors. These findings identify Arid3b as a candidate gene involved in the aetiology of human congenital malformations.

  5. Two-Source Energy Balance Model Evaluation for Mapping Evapotranspiration on the Semi- arid Southern High Plains

    Science.gov (United States)

    Gowda, P. H.; Chavez, J. L.; Colaizzi, P. D.; Evett, S. R.; Howell, T. A.; Copeland, K.

    2007-05-01

    Evapotranspiration (ET) is an essential component of the water balance and a major consumptive use of irrigation water and precipitation on cropland. In this study, we applied the Two-Source Energy Balance (T-SEB) model to estimate hourly ET from Landsat Thematic Mapper (TM) data for the semi-arid Southern High Plains of the United States where more than 90 percent of the groundwater withdrawals are used for irrigation. For this purpose, a Landsat TM image covering a major portion of the Southern High Plains (parts of Texas Panhandle and northeastern New Mexico) was acquired for 23 July 2006 for the overpass at 11:26 AM CST. Atmospheric correction on the TM imagery was done using MODTRAN, an atmospheric radiative transfer model. Comprehensive ground-truth data were collected to develop a detailed land use map showing major crops grown in the region. Performance of the T SEB model was evaluated by comparing mapped ET data with measured hourly ET data on five weighing lysimeters at Bushland, TX [35 Deg. 11' N, 102 Deg. 06' W; 1,170 m elevation MSL] managed by the Conservation and Production Research Laboratory, USDA-ARS. Lysimeter-measured ET rates varied from 0.24 to 0.71 mm/h. Comparison of estimated hourly mapped ET values with lysimetric measurements had an accuracy within 6% of the measured ET (r2=0.99), with a root mean squared error of 0.03 mm/h. These results support the use of the T-SEB model for the semi-arid Southern High Plains; however, more evaluation is needed for different agroclimatological conditions in the region.

  6. Photosynthesis and growth reduction with warming are driven by nonstomatal limitations in a Mediterranean semi-arid shrub.

    Science.gov (United States)

    León-Sánchez, Lupe; Nicolás, Emilio; Nortes, Pedro A; Maestre, Fernando T; Querejeta, José I

    2016-05-01

    Whereas warming enhances plant nutrient status and photosynthesis in most terrestrial ecosystems, dryland vegetation is vulnerable to the likely increases in evapotranspiration and reductions in soil moisture caused by elevated temperatures. Any warming-induced declines in plant primary production and cover in drylands would increase erosion, land degradation, and desertification. We conducted a four-year manipulative experiment in a semi-arid Mediterranean ecosystem to evaluate the impacts of a ~2°C warming on the photosynthesis, transpiration, leaf nutrient status, chlorophyll content, isotopic composition, biomass growth, and postsummer survival of the native shrub Helianthemum squamatum. We predicted that warmed plants would show reduced photosynthetic activity and growth, primarily due to the greater stomatal limitation imposed by faster and more severe soil drying under warming. On average, warming reduced net photosynthetic rates by 36% across the study period. Despite this strong response, warming did not affect stomatal conductance and transpiration. The reduction of peak photosynthetic rates with warming was more pronounced in a drought year than in years with near-average rainfall (75% and 25-40% reductions relative to controls, respectively), with no indications of photosynthetic acclimation to warming through time. Warmed plants had lower leaf N and P contents, δ (13)C, and sparser and smaller leaves than control plants. Warming reduced shoot dry mass production by 31%. However, warmed plants were able to cope with large reductions in net photosynthesis, leaf area, and shoot biomass production without changes in postsummer survival rates. Our findings highlight the key role of nonstomatal factors (biochemical and/or nutritional) in reducing net carbon assimilation rates and growth under warming, which has important implications for projections of plant carbon balance under the warmer and drier climatic scenario predicted for drylands worldwide

  7. Perched groundwater-surface interactions and their consequences in stream flow generation in a semi-arid headwater catchment

    Science.gov (United States)

    Molenat, Jerome; Bouteffeha, Maroua; Raclot, Damien; Bouhlila, Rachida

    2013-04-01

    In semi-arid headwater catchment, it is usually admitted that stream flow comes predominantly from Hortonian overland flow (infiltration excess overland flow). Consequently, subsurface flow processes, and especially perched or shallow groundwater flow, have not been studied extensively. Here we made the assumption that perched groundwater flow could play a significant role in stream flow generation in semi-arid catchment. To test this assumption, we analyzed stream flow time series of a headwater catchment in the Tunisian Cap Bon region and quantified the flow fraction coming from groundwater discharge and that from overland flow. Furthermore, the dynamics of the perched groundwater was analyzed, by focusing on the different perched groundwater-surface interaction processes : diffuse and local infiltration, diffuse exfiltration, and direct groundwater discharge to the stream channel. This work is based on the 2.6 km² Kamech catchment (Tunisia), which belongs to the long term Mediterranean hydrological observatory OMERE (Voltz and Albergel, 2002). Results show that even though Hortonian overland flow was the main hydrological process governing the stream flow generation, groundwater discharge contribution to the stream channel annually accounted for from 10% to 20 % depending on the year. Furthermore, at some periods, rising of groundwater table to the soil surface in bottom land areas provided evidences of the occurrence of saturation excess overland flow processes during some storm events. Reference Voltz , M. and Albergel , J., 2002. OMERE : Observatoire Méditerranéen de l'Environnement Rural et de l'Eau - Impact des actions anthropiques sur les transferts de masse dans les hydrosystèmes méditerranéens ruraux. Proposition d'Observatoire de Recherche en Environnement, Ministère de la Recherche.

  8. Bridging Estimates of Greenness in an Arid Grassland Using Field Observations, Phenocams, and Time Series Unmanned Aerial System (UAS) Imagery

    Science.gov (United States)

    Browning, D. M.; Tweedie, C. E.; Rango, A.

    2013-12-01

    Spatially extensive grasslands and savannas in arid and semi-arid ecosystems (i.e., rangelands) require cost-effective, accurate, and consistent approaches for monitoring plant phenology. Remotely sensed imagery offers these capabilities; however contributions of exposed soil due to modest vegetation cover, susceptibility of vegetation to drought, and lack of robust scaling relationships challenge biophysical retrievals using moderate- and coarse-resolution satellite imagery. To evaluate methods for characterizing plant phenology of common rangeland species and to link field measurements to remotely sensed metrics of land surface phenology, we devised a hierarchical study spanning multiple spatial scales. We collect data using weekly standardized field observations on focal plants, daily phenocam estimates of vegetation greenness, and very high spatial resolution imagery from an Unmanned Aerial System (UAS) throughout the growing season. Field observations of phenological condition and vegetation cover serve to verify phenocam greenness indices along with indices derived from time series UAS imagery. UAS imagery is classified using object-oriented image analysis to identify species-specific image objects for which greenness indices are derived. Species-specific image objects facilitate comparisons with phenocam greenness indices and scaling spectral responses to footprints of Landsat and MODIS pixels. Phenocam greenness curves indicated rapid canopy development for the widespread deciduous shrub Prosopis glandulosa over 14 (in April 2012) to 16 (in May 2013) days. The modest peak in greenness for the dominant perennial grass Bouteloua eriopoda occurred in October 2012 following peak summer rainfall. Weekly field estimates of canopy development closely coincided with daily patterns in initial growth and senescence for both species. Field observations improve the precision of the timing of phenophase transitions relative to inflection points calculated from phenocam

  9. Tropical Warm Semi-Arid Regions Expanding Over Temperate Latitudes In The Projected 21st Century

    Science.gov (United States)

    Rajaud, A.; de Noblet, N. I.

    2015-12-01

    Two billion people today live in drylands, where extreme climatic conditions prevail, and natural resources are limited. Drylands are expected to expand under several scenarios of climatic change. However, relevant adaptation strategies need to account for the aridity level: it conditions the equilibrium tree-cover density, ranging from deserts (hyper-arid) to dense savannas (sub-humid). Here we focus on the evolution of climatically defined warm semi-arid areas, where low-tree density covers can be maintained. We study the global repartition of these regions in the future and the bioclimatic shifts involved. We adopted a bioclimatological approach based on the Köppen climate classification. The warm semi-arid class is characterized by mean annual temperatures over 18°C and a rainfall-limitation criterion. A multi-model ensemble of CMIP5 projections for three representative concentration pathways was selected to analyze future conditions. The classification was first applied to the start, middle and end of the 20th and 21st centuries, in order to localize past and future warm semi-arid regions. Then, time-series for the classification were built to characterize trends and variability in the evolution of those regions. According to the CRU datasets, global expansion of the warm semi-arid area has already started (~+13%), following the global warming trend since the 1900s. This will continue according to all projections, most significantly so outside the tropical belt. Under the "business as usual" scenario, the global warm semi-arid area will increase by 30% and expand 12° poleward in the Northern Hemisphere, according to the multi-model mean. Drying drives the conversion from equatorial sub-humid conditions. Beyond 30° of latitude, cold semi-arid conditions become warm semi-arid through warming, and temperate conditions through combined warming and drying processes. Those various transitions may have drastic but also very distinct ecological and sociological

  10. Automated Extraction and Mapping for Desert Wadis from Landsat Imagery in Arid West Asia

    Directory of Open Access Journals (Sweden)

    Yongxue Liu

    2016-03-01

    Full Text Available Wadis, ephemeral dry rivers in arid desert regions that contain water in the rainy season, are often manifested as braided linear channels and are of vital importance for local hydrological environments and regional hydrological management. Conventional methods for effectively delineating wadis from heterogeneous backgrounds are limited for the following reasons: (1 the occurrence of numerous morphological irregularities which disqualify methods based on physical shape; (2 inconspicuous spectral contrast with backgrounds, resulting in frequent false alarms; and (3 the extreme complexity of wadi systems, with numerous tiny tributaries characterized by spectral anisotropy, resulting in a conflict between global and local accuracy. To overcome these difficulties, an automated method for extracting wadis (AMEW from Landsat-8 Operational Land Imagery (OLI was developed in order to take advantage of the complementarity between Water Indices (WIs, which is a technique of mathematically combining different bands to enhance water bodies and suppress backgrounds, and image processing technologies in the morphological field involving multi-scale Gaussian matched filtering and a local adaptive threshold segmentation. Evaluation of the AMEW was carried out in representative areas deliberately selected from Jordan, SW Arabian Peninsula in order to ensure a rigorous assessment. Experimental results indicate that the AMEW achieved considerably higher accuracy than other effective extraction methods in terms of visual inspection and statistical comparison, with an overall accuracy of up to 95.05% for the entire area. In addition, the AMEW (based on the New Water Index (NWI achieved higher accuracy than other methods (the maximum likelihood classifier and the support vector machine classifier used for bulk wadi extraction.

  11. Water Management For Drip Irrigated Corn In The Arid Southeastern Anatolia Project Area In Turkey

    Science.gov (United States)

    Yazar, A.; Gencel, B.

    Microirrigation has the potential to minimize application losses to evaporation, runoff and deep percolation; improve irrigation control with smaller, frequent applications; supply nutrients to the crop as needed; and improve crop yields. The Southeastern Anatolia Project (GAP), when completed, 1.7 million ha of land will be irrigated. Wa- ter supplies are limited, and traditional irrigation practices result in high losses and low irrigation efficiences. This study was conducted to evaluate surface drip irrigation on crop performance. The effect of irrigation frequency and amount on crop yield, yield components, water use, and water use efficiency of corn (Zea mays L., PIO- 3267) were investigated in the Harran Plain in the arid Southeastern Turkey on a clay textured Harran Soil Series. Irrigation frequencies were once in three-day, and once in six-day; irrigation levels varied from full (I-100), medium (I-67; 2/3rd of full), and low (I-33; 1/3rd of full). The full irrigation treatment received 100% of the cumula- tive evaporation within the irrigation interval. Liquid nitrogen was injected into the irrigation water throughout the growing season. Treatments received the same amount of fertilizers. Highest average corn grain yield (11920 kg/ha) was obtained from the full irrigation treatment (I-100) with six-day irrigation interval. Irrigation intervals did not affect corn yields; however, deficit irrigation affected crop yields by reducing seed mass, and the seed number. Maximum water use efficiency (WUE) was found as 2.27 kg/m3 in the I-33 treatment plots with three-day irrigation interval. On the clay soil at Harran, irrigation frequencies are less critical than proper irrigation management for drip irrigation systems to avoid water deficits that have a greater effect on corn yields. The results revealed that about 40% water saving is possible with drip irrigation as compared to traditional surface irrigation methods in the region.

  12. Hydrodynamics, vegetation transition and geomorphology coevolution in a semi-arid floodplain wetland.

    Science.gov (United States)

    Sandi, Steven; Rodriguez, Jose F.; Saco, Patricia M.; Riccardi, Gerardo; Wen, Li; Saintilan, Neil

    2016-04-01

    The Macquarie Marshes is a complex system of marshes, swamps and lagoons interconnected by a network of streams in the semi-arid region in north western NSW, Australia. The low-gradient topography of the site leads to channel breakdown processes where the river network becomes practically non-existent. As a result, the flow extends over large areas of wetland that later re-join and reform channels exiting the system. Vegetation in semiarid wetlands are often water dependent and flood tolerant species that rely on periodical floods in order to maintain healthy conditions. The detrimental state of vegetation in the Macquarie Marshes over the past few decades has been linked to decreasing inundation frequencies. Spatial distribution of flood tolerant overstory species such as River Red Gum and Black Box has not greatly changed since early 1990's, however; the condition of the vegetation patches shows a clear deterioration evidenced by terrestrial species encroachment on the wetland understory. On the other hand, areas of flood dependent species such as Water Couch and Common Reed have undergone complete succession to terrestrial species and dryland. In order to simulate the complex dynamics of the marshes we have developed an ecogeomorphological modelling framework that combines hydrodynamic, vegetation and channel evolution modules and in this presentation we provide an update on the status of the model. The hydrodynamic simulation provides spatially distributed values of inundation extent, duration, depth and recurrence to drive a vegetation model based on species preference to hydraulic conditions. It also provides velocities and shear stresses to assess geomorphological changes. Regular updates of stream network, floodplain surface elevations and vegetation coverage provide feedbacks to the hydrodynamic model. We presents also the development and assessment of transitional rules to determine if the water conditions have been met for different vegetation

  13. Calorific Value and Chemical Composition of Five Semi-Arid Mexican Tree Species

    Directory of Open Access Journals (Sweden)

    Maginot Ngangyo-Heya

    2016-03-01

    Full Text Available The current global energy crisis has generated growing interest in looking for alternatives to traditional fossil fuels, presenting lignocellulosic materials as a promising resource for sustainable energy production. In this paper, the calorific values and chemical composition of the trunks, branches, twigs and leaves of five timber species of the semi-arid land of Mexico (Helietta parvifolia (Gray Benth., Ebenopsis ebano (Berl. Barneby, Acacia berlandieri (Benth., Havardia pallens (Benth. Britton & Rose and Acacia wrightii (Benth. were determined according to international standards. The results highlighted the calorific value ranges of 17.56 to 18.61 MJ kg−1 in trunks, 17.15 to 18.45 MJ kg−1 in branches, 17.29 to 17.92 MJ kg−1 in twigs, and 17.35to 19.36 MJ kg−1 in leaves. The pH presented an acidic trend (3.95–5.64. The content of mineral elements varied in trunks (1.09%–2.29%, branches (0.86%–2.75%, twigs (4.26%–6.76% and leaves (5.77%–11.79%, showing the higher proportion in Ca (57.03%–95.53%, followed by K (0.95%–19.21% and Mg (0.88%–13.47%. The highest amount of extractives was obtained in the methanolic solvent (3.96%–17.03%. The lignin recorded values of 28.78%–35.84% for trunks, 17.14%–31.39% for branches and 20.61%–29.92% for twigs. Lignin showed a moderately strong correlation (r = 0.66 with calorific value, but the best mathematical model was registered with the calorific value depending on the pH and lignin (R2 = 58.86%.

  14. FAUNA OF COLEPTERA,TENEBRIORIDAE OF ARID COASTAL AND ISLAND ECOSYSTEMS OF THE CASPIAN SEA.

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    G. M. Abdurakhmanov

    2014-01-01

    Full Text Available Aim. The aim of the given paper is to expose species structure and geographical distribution of Coleoptera, Tenebrioridae (C, T of coastal and island ecosystem of the Caspian Sea. The given report is compiled of the matcrials, collected in different periods by authors (1961-2013 in the Caucasian part of the Caspian Sea, in the south of the European part of the Russian Federation, Kazakhstan, islands (the Chechen island, the Nord island. The Tuleniyisland. The Kulaly island, collective materials (ZIN; RAS, museum of Zoology of MSU, Institute NAN of Azerbaijan, National museum of Georgia and materials published (Kryzhanovsky, 1965, Medvedev, 1987, 1990; Medvedev, Nepesova, 1990; Shuster, 1934; Kaluzhnaya, 1982; Arzanov and others, 2004, Egorov, 2006.Methods. We used the traditional methods of collecting (hand picking, traps soil, soil traps light amplification light traps, processing and material definition. List of species composition discussed fauna composed by modern taxonomy using directories. Location. Coastal and island ecosystems of the Caspian sea.Results. Species structure and data on general and regional distribution of C,T of coastal and island ecosystems of the Caspian Sea is represented in the paper. Faund discussed is widely represented in the fauna of arid regions of land, especially in the fauna of subtropical deserts and semideserts.Main conclusions. Results of the study will be a step in the determination of age of the islands through the biological diversity and the consequent level regime of the Caspian Sea, as well as possible changes in the population structure of darkling beetles (Coleoptera: Tenebrionidae on island ecosystems.

  15. Water from Air: an Overlooked Source of Moisture in Arid and Semiarid Regions

    Science.gov (United States)

    McHugh, T. A.; Morrissey, E. M.; Reed, S.; Schwartz, E.; Hungate, B. A.

    2014-12-01

    Understanding water sources, use, and availability in Earth's arid and semiarid lands is fundamental to understanding and forecasting dryland ecosystem function. While it is accepted that drylands can obtain water from sources other than precipitation (e.g., from dew), little is known about how liquid water supplied to dryland soils via water vapor adsorption (WVA) helps to regulate dryland communities and their activity. WVA - the adsorption of water vapor and subsequent formation of liquid water within soil - occurs at times when the relative humidity in the soil atmosphere is lower than the relative humidity of the overlying air. Surprisingly little research has been focused on WVA, though environmental conditions are such that this phenomenon is likely to occur quite regularly in dryland regions throughout the world. Here we used an observational study in a semiarid grassland and a series of laboratory experiments to explore the role of WVA in providing soil moisture and regulating soil microbial activity (assessed as CO2 efflux rates). Through the introduction of 18O liquid water into the atmosphere of a closed system, we were able to trace the movement of water from the atmosphere to the soil via WVA under a range of temperature conditions. Both in the field setting and in the laboratory, elevated rates of soil respiration were observed with WVA-induced increases in soil moisture. Taken together, these results indicate that vapor adsorption is occurring under a variety of common conditions and provide compelling evidence that this water source may strongly influence the activity of soil microorganisms, including fundamental aspects of the soil carbon cycle.

  16. BVOCs emission in a semi-arid grassland under climate warming and nitrogen deposition

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    H. J. Wang

    2012-01-01

    Full Text Available Biogenic volatile organic compounds (BVOCs profoundly affect atmospheric chemistry and ecosystem functioning. BVOCs emission and their responses to global change are still unclear in grasslands, which cover one quarter of the Earth's land surface and are currently undergoing the largest changes. Over two growing seasons, we conducted a field experiment in a semi-arid grassland (Inner Mongolia, China to examine the emission and the responses of BVOCs emissions to warming and nitrogen deposition. The natural emission rate (NER of monoterpene (dominant BVOCs here is 107 ± 16 μg m−2 h−1 in drought 2007, and 266 ± 53 μg m−2 h−1 in wet 2008, respectively. Warming decreased the standard emission factor (SEF by 24% in 2007, while increased it by 43% in 2008. The exacerbated soil moisture loss caused by warming in dry season might be responsible for the decrease of SEF in 2007. A possible threshold of soil moisture (8.2% (v/v, which controls the direction of warming effects on monoterpene emission, existed in the semiarid grassland. Nitrogen deposition decreased the coverage of Artemisia frigida and hence reduced the NER by 24% across the two growing seasons. These results suggest that the grasslands dominated by the extended Artemisia frigida are an important source for BVOCs, while the responses of their emissions to global changes are more uncertain since they depend on multifactorial/in-situ/conditions.

  17. BVOCs emission in a semi-arid grassland under climate warming and nitrogen deposition

    Directory of Open Access Journals (Sweden)

    H. J. Wang

    2012-04-01

    Full Text Available Biogenic volatile organic compounds (BVOCs profoundly affect atmospheric chemistry and ecosystem functioning. BVOCs emission and their responses to global change are still unclear in grasslands, which cover one quarter of the Earth's land surface and are currently undergoing the largest changes. Over two growing seasons, we conducted a field experiment in a semi-arid grassland (Inner Mongolia, China to examine the emission and the responses of BVOCs emissions to warming and nitrogen deposition. The natural emission rate (NER of monoterpene (dominant BVOCs here is 107 ± 16 μg m−2 h−1 in drought 2007, and 266 ± 53 μg m−2 h−1 in wet 2008, respectively. Warming decreased the standard emission factor (SEF by 24% in 2007, while it increased by 43% in 2008. The exacerbated soil moisture loss caused by warming in dry season might be responsible for the decrease of SEF in 2007. A possible threshold of soil moisture (8.2% (v/v, which controls the direction of warming effects on monoterpene emission, existed in the semiarid grassland. Nitrogen deposition decreased the coverage of Artemisia frigida and hence reduced the NER by 24% across the two growing seasons. These results suggest that the grasslands dominated by the extended Artemisia frigida are an important source for BVOCs, while the responses of their emissions to global changes are more uncertain since they depend on multifactorial in-situ conditions.

  18. Semi-arid Vegetation Pattern, Stability and Suitability to Suppress Sand Movement in Central Sudan

    Directory of Open Access Journals (Sweden)

    N.K.N. Al-Amin

    2011-01-01

    Full Text Available Moving sand that threatens Gezira scheme is the dominant land degradation feature in central Sudan and the front line defence is the sparse scattered natural vegetation of the area. The study aimed to assess the role of this vegetation to suppress drifting sand and to monitor their ability to face the impact of climate change and human activity (deforestation. The dimensions of the sand captured by single tree of dominant species, Acacia tortilis, Leptadenia pyrotechnica, Prosopis juliflora and Panicum turgidum were measured and the volumes were calculated. To picture the drought pattern 5-year running means of annual rainfalls (1941-2007 of the study area were calculated and compared with long-term mean. Deforestation was indicated by local community wood consumption in relation to the average woody biomass (in good condition. The results show that scattered trees of the right densities had potentiality to settle drifting sand, but they were subjected to 20 years dry seasons followed by only 4 wet years and now are subjected to a new era of dry spell. This condition is not in favour of the semi-arid vegetation pattern sustainability and a suitable measure to enhance natural regeneration is needed. In addition, the community's wood demand was higher than the resource, where a person would destroy 0.5 ha/year compared to 0.9 ha/year per person available reveals the magnitude of deforestation. Encouragement of farmers to use alternative energy sources and functional application of laws and regulations to protect the existing vegetation rem ain crucial.

  19. Persistence at distributional edges: Columbia spotted frog habitat in the arid Great Basin, USA

    Science.gov (United States)

    Arkle, Robert S.; Pilliod, David S.

    2015-01-01

    A common challenge in the conservation of broadly distributed, yet imperiled species is understanding which factors facilitate persistence at distributional edges, locations where populations are often vulnerable to extirpation due to changes in climate, land use, or distributions of other species. For Columbia spotted frogs (Rana luteiventris) in the Great Basin (USA), a genetically distinct population segment of conservation concern, we approached this problem by examining (1) landscape-scale habitat availability and distribution, (2) water body-scale habitat associations, and (3) resource management-identified threats to persistence. We found that areas with perennial aquatic habitat and suitable climate are extremely limited in the southern portion of the species’ range. Within these suitable areas, native and non-native predators (trout and American bullfrogs [Lithobates catesbeianus]) are widespread and may further limit habitat availability in upper- and lower-elevation areas, respectively. At the water body scale, spotted frog occupancy was associated with deeper sites containing abundant emergent vegetation and nontrout fish species. Streams with American beaver (Castor canadensis) frequently had these structural characteristics and were significantly more likely to be occupied than ponds, lakes, streams without beaver, or streams with inactive beaver ponds, highlighting the importance of active manipulation of stream environments by beaver. Native and non-native trout reduced the likelihood of spotted frog occupancy, especially where emergent vegetation cover was sparse. Intensive livestock grazing, low aquatic connectivity, and ephemeral hydroperiods were also negatively associated with spotted frog occupancy. We conclude that persistence of this species at the arid end of its range has been largely facilitated by habitat stability (i.e., permanent hydroperiod), connectivity, predator-free refugia, and a commensalistic interaction with an ecosystem

  20. Human response and adaptation to drought in the arid zone: lessons from southern Africa

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    W. R.J. Dean

    2009-12-01

    Full Text Available Human adaptation and response to drought is primarily through evasion or endurance. A review of historical agricultural practices in southern Africa demonstrates evidence of drought evasion response strategies in well-established transhumance routes, where herders move livestock on a seasonal basis in order to exploit resources subject to different climatic regimes. European settlers to the arid regions of South Africa quickly recognised the necessity of these evasion options to survive drought, and adopted the transhumance practices of indigenous farmers. Areas of geographically diverse resource bases became hotly contested by settlers and indigenous farmers. The success of evasion systems are shown to hinge on good social and institutional support structures. When movement is not an option, drought endurance is pursued by attempting to limit the damage to the natural resource base. This is through a number of means such as forage conservation, varying livestock types and numbers, water and soil conservation and taking up alternative livelihood options. State responses to drought over the last century reflect the general South African pattern of racially divided and unjust policies relating to resource access. Historically the state provided considerable support to white commercial farmers. This support was frequently contradictory in its aims and generally was inadequate to enable farmers to cope with drought. Since the advent of democracy in 1994, the state has intervened less, with some support extended to previously disadvantaged and poor communal farmers. Climate change predictions suggest an increase in drought, suggesting that the adoption of mitigating strategies should be a matter of urgency. To do this South Africa needs to build social and institutional capacity, strive for better economic and environmental sustainability, embed drought-coping mechanisms into land restitution policy to ensure the success of this programme, and

  1. The yearly amount and characteristics of deep-buried phreatic evaporation in hyper-arid areas

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    H. Li

    2015-12-01

    Full Text Available Water scarcity is the primary cause of land deterioration, so finding new available water resources is crucial to ecological restoration. We investigated a hyper-arid Gobi location in the Dunhuang Mogao Grottoes in this work wherein the burial depth of phreatic water is over 200 m. An air-conditioner was used in a closed greenhouse to condense and measure the yearly amount of phreatic evaporation (PE from 2010 to 2015. The results show that the annual quantity of PE is 4.52 mm, and that the PE has sinusoidal characteristics. The average PE is 0.0183 mm d-1 from March to November. Accordingly, by monitoring the annual changes in soil–air temperature and humidity to a depth of 5.0 m, we analyzed the water migration mechanism in the heterothermozone (subsurface zone of variable temperature. The results show that, from March to November, the temperature and absolute humidity (AH increase. This is due to the flow of solar heat entering the soil – the soil subsequently releases moisture and the soil is in a state of increasing AH so that evaporation occurs. From November to March, the temperature decreases. Now, the soil absorbs water vapor and AH is in a state of decline. Thus, it is temperature alternation in the heterothermozone – due to solar heat transfer – that provides the main driving power for PE. When it drives water vapor to move downwards in the heterothermozone, a small part is reversed upwards and evaporates. Solar radiation intensity dominates the annual sinusoidal PE characteristics.

  2. The causes of flow regime shifts in the semi-arid Hailiutu River, Northwest China

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    Z. Yang

    2012-01-01

    Full Text Available Identifying the causes (climate vs. human activities for hydrological variability is a major challenge in hydrology. This paper examines the flow regime shifts, changes in the climatic variables such as precipitation, evaporation, temperature, and crop area in the semi-arid Hailiutu catchment in the middle section of the Yellow River by performing several statistical analyses. The Pettitt test, cumulative sum charts (CUSUM, regime shift index (RSI method, and harmonic analysis were carried out on annual, monthly, and daily discharges. Four major shifts in the flow regime have been detected in 1968, 1986, 1992 and 2001. Characteristics of the flow regime were analyzed in the five periods: 1957–1967, 1968–1985, 1986–1991, 1992–2000, and 2001–2007. From 1957 to 1967, the flow regime reflects quasi natural conditions of the high variability and larger amplitude of 6 months periodic fluctuations. The river peak flow was reduced by the construction of two reservoirs in the period 1968–1985. In the period of 1986–1991, the river discharge further decreased due to the combined influence of river diversions and increase of groundwater extractions for irrigation. In the fourth period of 1992–2000, the river discharge reached lowest flow and variation in corresponding to a large increase in crop area. The flow regime recovered, but not yet to natural status in the fifth period of 2001–2007. Climatic factors are found not likely responsible for the changes in the flow regime, but the changes in the flow regime are corresponding well to historical land use policy changes.

  3. A review of groundwater recharge estimation in humid and semi-arid African regions

    Science.gov (United States)

    Chung, Il-Moon; Kim, Nam Won

    2016-04-01

    For the review of African recharge estimation, the distinct methods such as the geochemical approach, a method using groundwater level data, the streamflow method, and the water balance methods were first outlined. The major challenge of an African recharge study is the lack of basic data. Thus, this work suggests how to deal with this limitation and from future perspective using recently developed technologies such as RS, GIS, etc. With the rapid growth of information technology, more and more data, in terms of both volume and variety, are expected to be made available on the internet in the near future. RS technology has a great potential to revolutionize the groundwater development and management in the future by providing unique and completely new hydrological and hydrogeological data. However, at present, the RS data should be considered along with the conventional field data. In spite of the weaknesses of water balance methods in semi-arid areas, recently developed water balance methods combined with GIS technology are powerful tools for estimating groundwater re-charge, when spatial-temporal variability of components in water balance is taken into account (Lerner et al., 1990; De Vries and Simmers, 2002; Eilers et al., 2007).When enough data sets are available, integrated surface-groundwater modeling is recommended for more accurate estimation of groundwater recharge and discharge. Acknowledgements This work was supported by a grant(14RDRP-B076275-01-000000) from Infrastructure and transportation technology promotion research Program funded by the Ministry of Land, Infrastructure and Transport of Korean government.

  4. Streamflow allocation in arid watersheds: a case study in Northwestern China

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    C. He

    2012-07-01

    Full Text Available This paper proposes a framework for allocating water resources among the upper, middle, and lower reaches of arid watersheds to meet the multiple demands for water, including rehabilitation of downstream ecosystem. The framework includes: (1 hydrologic simulation of distribution of water resources in the study watershed; (2 development of water allocation criteria; and (3 implementation of the water allocation plan. The advantages of the proposed framework are: (1 spatial integration; (2 multiple objectives; (3 incorporation of local needs through participatory decision making; and (4 dynamic evaluation.

    The framework was applied to the Heihe watershed, a large inland (terminal lake watershed with a drainage area of over 128 000 km2 in Northwestern China. Simulation of the daily river flows for the period of 1990–2000 by the Distributed Large Basin Runoff Model shows that Qilian Mountain in the upper reach produced most of the runoff in the watershed, and the increased withdrawals of water for agricultural irrigation, industrial development, and municipal supplies at the middles reach oasis reduced the annual mean discharge by approximately 0.18 × 109 m3 over the simulation period, making the middle reach unable to deliver the mandated amount of 0.95 × 109 m3 water downstream by the State Council, under normal climatic conditions. Changes in land use practices need to be implemented to achieve the mandated water allocation plan. The paper suggests that a participatory watershed planning approach involving multiple stakeholders in the water allocation process be undertaken to address key questions regularly, including how much water should be allocated to what uses and for whom and at what price?

  5. Passive diffusion sampling of sulfur dioxide in India: Impact assessment on arid areas

    Institute of Scientific and Technical Information of China (English)

    S. Kumar; M. Mohan; R. Datta

    2002-01-01

    Environmental constraints have drastically limited options of sustainable developmentand have severely offset many developmental schemes. In this paper, possibilities of acidic depo-sition, as a counter measure of desertification, are analyzed. Seasonal data of ambient sulfur di-oxide, pH of rain water and soil acidity are collected for over an year and analyzed. Arid environ-ment of surrounding areas of Delhi is considered and analyzed. Though ambient sulfur depositionis well below critical level, it might not be truly indicative of plant survival in arid areas. Results maybe useful in arid area afforestation, and polluting industries relocation, which holds tremendouspotential vis-a-vis sustainable development.

  6. Biomass and habitability potential of clay minerals- and iron-rich environments: Testing novel analogs for Mars Science Laboratory landing sites candidates

    Science.gov (United States)

    Bonaccorsi, Rosalba; McKay, Christopher P.; Chen, Bin

    2010-06-01

    The landing site of the next mission to Mars (the US 2011 Mars Science Laboratory) will include phyllosilicate outcrops as targets for investigating the geological and biological history of the planet. In this context, we present a preliminary study assessing the living biomass and habitability potential in mineralogical Mars analogs by means of multi-component investigations (X-ray diffraction, microRaman spectroscopy and SEMEDX). Phyllosilicate and hematite-rich deposits from the Atacama Desert (Chile), Death Valley (CA), and the California Coast, encompassing a broad arid to hyper-arid climate range (annual rainfall cyanobacteria) were successfully captured.

  7. Validation of MODIS and Deep Blue aerosol optical depth retrievals in an arid/semi-arid region of northwest China

    Institute of Scientific and Technical Information of China (English)

    Xia Li; Xiangao Xia; Shengli Wang; Jietai Mao; Yan Liu

    2012-01-01

    The global aerosol optical depth (AOD or τ) has been retrieved using the Dark Target algorithm (the C004 and C005 products) and the Deep Blue algorithm (DB product).Few validations have thus far been performed in arid/semi-arid regions,especially in northwest China.The ground-based remote sensing of AOD from sun photometers at four sites in Xinjiang during the years 2002-2003 is used to validate aerosol products,including C004,C005 and DB of the Moderate Resolution Imaging Spectroradiometer (MODIS).The results show substantial improvement in the C005 aerosol product over the C004 product.The average correlation coefficient of regression with ground measurements increased from 0.59 to 0.69,and the average offset decreased from 0.28 to 0.13.The slopes of the linear regressions tended to be close to unity.The percentage of AODs falling within the retrieval errors of 30% (or △τ =±0.1 ± 0.2τ)increased from 16.1% to 45.6%.The best retrievals are obtained over an oasis region,whereas the worst are obtained over urban areas.Both the MODIS C004 and C005 products overestimate AOD,which is likely related to improper assumptions of the aerosol model and of the estimation of surface reflectance.An encouraging result has been derived with regard to validation of the DB AOD.Overall,the average offset,slope and correlation coefficient of regression with sun-photometer measurements are -0.04,0.88 and 0.85,respectively.Approximately 73% of the DB AOD retrievals fall within the expected error of 30%.Underestimation of the AOD by the DB products is observed.The aerosol