WorldWideScience

Sample records for program arid ecosystems

  1. Reading the Signs: Spatial vegetation patterns, arid ecosystems and desertification

    NARCIS (Netherlands)

    Kefi, S.

    2008-01-01

    Human footprint on ecosystems is growing, and ecosystems cope with these changes in different ways. Arid ecosystems are likely to shift abruptly to desert in a sudden and often irreversible manner because of climatic changes or human activities. Such ecosystem shifts can even happen when external

  2. Applying an Avian Index of Biological Integrity to Assess and Monitor Arid and Semi-arid Riparian Ecosystems

    Science.gov (United States)

    2009-01-01

    ERDC TN-EMRRP-RQ-01 January 2009 Applying an Avian Index of Biological Integrity to Assess and Monitor Arid and Semi - arid Riparian Ecosystems by...00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Applying an Avian Index of Biological Integrity to Assess and Monitor Arid and Semi - arid Riparian...biological integrity to assess and monitor arid and semi - arid riparian eco- systems. EMRRP Technical Notes Collection (ERDC TN-EMRRP-RQ-01). Vicksburg, MS

  3. 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

  4. Limits on carbon sequestration in arid blue carbon ecosystems.

    Science.gov (United States)

    Schile, Lisa M; Kauffman, J Boone; Crooks, Stephen; Fourqurean, James W; Glavan, Jane; Megonigal, J Patrick

    2017-04-01

    Coastal ecosystems produce and sequester significant amounts of carbon ("blue carbon"), which has been well documented in humid and semi-humid regions of temperate and tropical climates but less so in arid regions where mangroves, marshes, and seagrasses exist near the limit of their tolerance for extreme temperature and salinity. To better understand these unique systems, we measured whole-ecosystem carbon stocks in 58 sites across the United Arab Emirates (UAE) in natural and planted mangroves, salt marshes, seagrass beds, microbial mats, and coastal sabkha (inter- and supratidal unvegetated salt flats). Natural mangroves held significantly more carbon in above- and belowground biomass than other vegetated ecosystems. Planted mangrove carbon stocks increased with age, but there were large differences for sites of similar age. Soil carbon varied widely across sites (2-367 Mg C/ha), with ecosystem averages that ranged from 49 to 156 Mg C/ha. For the first time, microbial mats were documented to contain soil carbon pools comparable to vascular plant-dominated ecosystems, and could arguably be recognized as a unique blue carbon ecosystem. Total ecosystem carbon stocks ranged widely from 2 to 515 Mg C/ha (seagrass bed and mangrove, respectively). Seagrass beds had the lowest carbon stock per unit area, but the largest stock per total area due to their large spatial coverage. Compared to similar ecosystems globally, mangroves and marshes in the UAE have lower plant and soil carbon stocks; however, the difference in soil stocks is far larger than with plant stocks. This incongruent difference between stocks is likely due to poor carbon preservation under conditions of weakly reduced soils (200-350 mV), coarse-grained sediments, and active shoreline migration. This work represents the first attempt to produce a country-wide coastal ecosystem carbon accounting using a uniform sampling protocol, and was motivated by specific policy goals identified by the Abu Dhabi Global

  5. 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

  6. 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.

  7. 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.

  8. Co-evolution and thresholds in arid floodplain wetland ecosystems.

    Science.gov (United States)

    Sandi, Steven; Rodriguez, Jose; Riccardi, Gerardo; Wen, Li; Saintilan, Neil

    2017-04-01

    Vegetation in arid floodplain wetlands consist of water dependent and flood tolerant species that rely on periodical floods in order to maintain healthy conditions. The floodplain often consist of a complex system of marshes, swamps and lagoons interconnected by a network of streams and poorly defined rills. Over time, feedbacks develop between vegetation and flow paths producing areas of flow obstruction and flow concentration, which combined with depositional and erosional process lead to a continuous change on the position and characteristics of inundation areas. This coevolution of flow paths and vegetation can reach a threshold that triggers major channel transformations and abandonment of wetland areas, in a process that is irreversible. The Macquarie Marshes is a floodplain wetland complex in the semi-arid region of north western NSW, Australia. The site is characterised by a low-gradient topography that leads to channel breakdown processes where the river network becomes practically non-existent and the flow extends over large areas of wetland that later re-join and reform channels exiting the system. Due to a combination of climatic and anthropogenic pressures, the wetland ecosystem in the Macquarie Marshes has deteriorated over the past few decades. This has been linked to decreasing inundation frequencies and extent, with whole areas of flood dependent species such as Water Couch and Common Reed undergoing complete succession to terrestrial species and dryland. In this presentation we provide an overview of an ecogeomorphological model that we have developed in order to simulate the complex dynamics of the marshes. The model combines hydrodynamic, vegetation and channel evolution modules. We focus on the vegetation component of the model and the transitional rules to predict wetland invasion by terrestrial vegetation.

  9. Guidelines for Establishing Monitoring Programs to Assess the Success of Riparian Restoration Efforts in Arid and Semi-Arid Landscapes

    Science.gov (United States)

    2006-08-01

    ERDC TN-EMRRP-SR-50 1 Guidelines for Establishing Monitoring Programs to Assess the Success of Riparian Restoration Efforts in Arid and Semi ...Management and Restoration Research Program (EMRRP) work unit titled “Techniques for Reestablishing Riparian Hardwoods in Arid and Semi - arid ...Regions.” The objectives of this work are to provide technology to improve capabilities of restoring riparian areas in arid and semi - arid regions. The

  10. 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

  11. Impacts of altered precipitation regimes on soil communities and biogeochemistry in arid and semi-arid ecosystems.

    Science.gov (United States)

    Nielsen, Uffe N; Ball, Becky A

    2015-04-01

    Altered precipitation patterns resulting from climate change will have particularly significant consequences in water-limited ecosystems, such as arid to semi-arid ecosystems, where discontinuous inputs of water control biological processes. Given that these ecosystems cover more than a third of Earth's terrestrial surface, it is important to understand how they respond to such alterations. Altered water availability may impact both aboveground and belowground communities and the interactions between these, with potential impacts on ecosystem functioning; however, most studies to date have focused exclusively on vegetation responses to altered precipitation regimes. To synthesize our understanding of potential climate change impacts on dryland ecosystems, we present here a review of current literature that reports the effects of precipitation events and altered precipitation regimes on belowground biota and biogeochemical cycling. Increased precipitation generally increases microbial biomass and fungal:bacterial ratio. Few studies report responses to reduced precipitation but the effects likely counter those of increased precipitation. Altered precipitation regimes have also been found to alter microbial community composition but broader generalizations are difficult to make. Changes in event size and frequency influences invertebrate activity and density with cascading impacts on the soil food web, which will likely impact carbon and nutrient pools. The long-term implications for biogeochemical cycling are inconclusive but several studies suggest that increased aridity may cause decoupling of carbon and nutrient cycling. We propose a new conceptual framework that incorporates hierarchical biotic responses to individual precipitation events more explicitly, including moderation of microbial activity and biomass by invertebrate grazing, and use this framework to make some predictions on impacts of altered precipitation regimes in terms of event size and frequency as

  12. 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

  13. 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......, confirming that care should be taken before applying temperature response curves for hot dry semi-arid regions when partitioning NEE into gross primary productivity (GPP) and ecosystem respiration (Reco). Partitioning was instead done using light response curves. The values of ε ranged between 0.02g carbon...

  14. Biocrust-forming mosses mitigate the negative impacts of increasing aridity on ecosystem multifunctionality in drylands.

    Science.gov (United States)

    Delgado-Baquerizo, Manuel; Maestre, Fernando T; Eldridge, David J; Bowker, Matthew A; Ochoa, Victoria; Gozalo, Beatriz; Berdugo, Miguel; Val, James; Singh, Brajesh K

    2016-03-01

    The increase in aridity predicted with climate change will have a negative impact on the multiple functions and services (multifunctionality) provided by dryland ecosystems worldwide. In these ecosystems, soil communities dominated by mosses, lichens and cyanobacteria (biocrusts) play a key role in supporting multifunctionality. However, whether biocrusts can buffer the negative impacts of aridity on important biogeochemical processes controlling carbon (C), nitrogen (N), and phosphorus (P) pools and fluxes remains largely unknown. Here, we conducted an empirical study, using samples from three continents (North America, Europe and Australia), to evaluate how the increase in aridity predicted by climate change will alter the capacity of biocrust-forming mosses to modulate multiple ecosystem processes related to C, N and P cycles. Compared with soil surfaces lacking biocrusts, biocrust-forming mosses enhanced multiple functions related to C, N and P cycling and storage in semiarid and arid, but not in humid and dry-subhumid, environments. Most importantly, we found that the relative positive effects of biocrust-forming mosses on multifunctionality compared with bare soil increased with increasing aridity. These results were mediated by plant cover and the positive effects exerted by biocrust-forming mosses on the abundance of soil bacteria and fungi. Our findings provide strong evidence that the maintenance of biocrusts is crucial to buffer negative effects of climate change on multifunctionality in global drylands. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  15. Interspecific facilitation and critical transitions in arid ecosystems

    NARCIS (Netherlands)

    Verwijmeren, M.|info:eu-repo/dai/nl/380491796

    2016-01-01

    The human impact on the climate system and on ecosystems has rapidly increased over the last century. Moreover, forecasts by global climate models predict that increasing temperatures and more frequent and longer drought periods will impose an increasing pressure on ecosystems over the coming

  16. 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.

  17. Applicability of toxicity bioassays to ecological risk assessment in arid and semiarid ecosystems.

    Energy Technology Data Exchange (ETDEWEB)

    Markwiese, J. T.; Ryti, R. T.; Hooten, M. M.; Michael, D. I.; Hlohowskyj, I.; Environmental Assessment; Neptune and Company, Inc.

    2001-01-01

    Substantial tracts of land in the southwestern and western U.S. are undergoing or will require ERA. Toxicity bioassays employed in baseline ERAs are, for the most part. representative of mesic systems, and highly standardized test species (e.g., lettuce, earthworm) are generally not relevant to arid system toxicity testing. Conversely, relevant test species are often poorly characterized with regard to toxicant sensitivity and culture conditions. The applicability of toxicity bioassays to ecological risk assessment in arid and semiarid ecosystems was reviewed for bacteria and fungi, plants, terrestrial invertebrates, and terrestrial vertebrates. Bacteria and fungi are critical to soil processes, and understanding their ecology is important to understanding the ecological relevance of bioassays targeting either group. Terrestrial bacteria require a water film around soil particles to be active, while soil fungi can remain active in extremely dry soils. It is therefore expected that fungi will be of greater importance to arid and semiarid systems (Whitford 1989). If microbial processes are to be measured in soils of arid environments, it is recommended that bioassays target fungi. Regardless of the taxa studied, problems are associated with the standardization and interpretability of microbial tests, and regulatory acceptance may hinder widespread incorporation of microbial toxicity bioassays in arid system risk assessments. Plant toxicity bioassays are gaining recognition as sensitive indicators of soil conditions because they can provide a cost-effective and relatively rapid assessment of soil quality for both pre- and postremediation efforts. Although the choices of suitable plant species for assessing mesic system soils are numerous, the choices for arid system soils are limited. Guidance is provided for evaluating plant species with regard to their suitability for serving as representative arid system flora. Terrestrial invertebrates can survive and flourish in

  18. Carbon cycle responses of semi-arid ecosystems to positive asymmetry in rainfall.

    Science.gov (United States)

    Haverd, Vanessa; Ahlström, Anders; Smith, Benjamin; Canadell, Josep G

    2017-02-01

    Recent evidence shows that warm semi-arid ecosystems are playing a disproportionate role in the interannual variability and greening trend of the global carbon cycle given their mean lower productivity when compared with other biomes (Ahlström et al. 2015 Science, 348, 895). Using multiple observations (land-atmosphere fluxes, biomass, streamflow and remotely sensed vegetation cover) and two state-of-the-art biospheric models, we show that climate variability and extremes lead to positive or negative responses in the biosphere, depending on vegetation type. We find Australia to be a global hot spot for variability, with semi-arid ecosystems in that country exhibiting increased carbon uptake due to both asymmetry in the interannual distribution of rainfall (extrinsic forcing), and asymmetry in the response of gross primary production (GPP) to rainfall change (intrinsic response). The latter is attributable to the pulse-response behaviour of the drought-adapted biota of these systems, a response that is estimated to be as much as half of that from the CO 2 fertilization effect during 1990-2013. Mesic ecosystems, lacking drought-adapted species, did not show an intrinsic asymmetric response. Our findings suggest that a future more variable climate will induce large but contrasting ecosystem responses, differing among biomes globally, independent of changes in mean precipitation alone. The most significant changes are occurring in the extensive arid and semi-arid regions, and we suggest that the reported increased carbon uptake in response to asymmetric responses might be contributing to the observed greening trends there. © 2016 John Wiley & Sons Ltd.

  19. Soil respiration in different agricultural and natural ecosystems in an arid region.

    Directory of Open Access Journals (Sweden)

    Liming Lai

    Full Text Available The variation of different ecosystems on the terrestrial carbon balance is predicted to be large. We investigated a typical arid region with widespread saline/alkaline soils, and evaluated soil respiration of different agricultural and natural ecosystems. Soil respiration for five ecosystems together with soil temperature, soil moisture, soil pH, soil electric conductivity and soil organic carbon content were investigated in the field. Comparing with the natural ecosystems, the mean seasonal soil respiration rates of the agricultural ecosystems were 96%-386% higher and agricultural ecosystems exhibited lower CO(2 absorption by the saline/alkaline soil. Soil temperature and moisture together explained 48%, 86%, 84%, 54% and 54% of the seasonal variations of soil respiration in the five ecosystems, respectively. There was a significant negative relationship between soil respiration and soil electrical conductivity, but a weak correlation between soil respiration and soil pH or soil organic carbon content. Our results showed that soil CO(2 emissions were significantly different among different agricultural and natural ecosystems, although we caution that this was an observational, not manipulative, study. Temperature at the soil surface and electric conductivity were the main driving factors of soil respiration across the five ecosystems. Care should be taken when converting native vegetation into cropland from the point of view of greenhouse gas emissions.

  20. Food habits of rodents inhabiting arid and semi-arid ecosystems of central New Mexico

    Science.gov (United States)

    Hope, Andrew G.; Parmenter, Robert R.

    2007-01-01

    In this study, we describe seasonal dietary composition for 15 species of rodents collected in all major habitats on the Sevilleta National Wildlife Refuge (Socorro County) in central New Mexico. A comprehensive literature review of food habits for these species from throughout their distribution also is provided. We collected rodents in the field during winter, spring and late summer in 1998 from six communities: riparian cottonwood forest; piñon-juniper woodland; juniper-oak savanna; mesquite savanna; short-grass steppe; and Chihuahuan Desert scrubland. Rodents included Spermophilus spilosoma (Spotted Ground Squirrel), Perognathus flavescens (Plains Pocket Mouse), Perognathus flavus (Silky Pocket Mouse), Dipodomys merriami (Merriam’s Kangaroo Rat), Dipodomys ordii (Ord’s Kangaroo Rat), Dipodomys spectabilis (Banner-tailed Kangaroo Rat), Reithrodontomys megalotis (Western Harvest Mouse), Peromyscus boylii (Brush Mouse), Peromyscus eremicus (Cactus Mouse), Peromyscus leucopus (White-footed Mouse), Peromyscus truei (Piñon Mouse), Onychomys arenicola (Mearn’s Grasshopper Mouse), Onychomys leucogaster (Northern Grasshopper Mouse), Neotoma albigula/leucodon (White-throated Woodrats), and Neotoma micropus (Southern Plains Woodrat). We collected stomach contents of all species, and cheek-pouch contents of heteromyids, and quantified them in the laboratory. We determined seasonal diets in each habitat by calculating mean percentage volumes of seeds, arthropods and green vegetation (plant leaves and stems) for each species of rodent. Seeds consumed by each rodent were identified to genus, and often species, and quantified by frequency counts. Comparisons of diets between and among species of rodents, seasons, and ecosystems were also examined. We provide an appendix of all plant taxa documented.

  1. Modeling Ecosystem Services in an Arid Landscape Using the InVEST Tool

    Science.gov (United States)

    In this paper we describe the US Environmental Protection Agency’s Southwest Ecosystem Services Program (SwESP) initial efforts to use the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) tool to quantify and map the values of multiple ecosystem services in the S...

  2. Book title: Exotic brome grasses in arid and semi-arid ecosystems of the western US: causes, consequences, and management implications

    Science.gov (United States)

    Exotic invasive annual grass research and management in arid and semiarid ecosystems of the western US have historically focused on the outcome of efforts to reduce weed abundance. Given the current impact of invasive annual grasses and their continued spread in this region, we assessed components ...

  3. Increased productivity in wet years drives a decline in ecosystem stability with nitrogen additions in arid grasslands.

    Science.gov (United States)

    Wang, Junfeng; Knops, Johannes M H; Brassil, Chad E; Mu, Chunsheng

    2017-07-01

    Adding nutrients to nutrient-limited ecosystems typically lowers plant diversity and decreases species asynchrony. Both, in turn, decrease the stability of productivity in the response to negative climate fluctuations such as droughts. However, most classic studies examining stability have been done in relatively wet grasslands dominated by perennial grasses. We examined how nutrient additions influence the stability of productivity to rainfall variability in an arid grassland with a mix of perennial and annual species. Of the nutrients, only nitrogen increased productivity, and only in wet years. In addition, only nitrogen decreased the stability of productivity. Thus, nutrient addition makes ecosystem productivity less stable in both wet and arid grasslands. However, the mechanism is very different. In contrast to wet grasslands, adding nitrogen to an arid grassland did not decrease diversity. Rather, stability decreased with nitrogen addition due to an increase in annual species that increased productivity. In other words, in our arid grassland, nitrogen addition decreased ecosystem stability because of increased ecosystem responsiveness to positive climate fluctuations. These climate fluctuations were facilitated by annual species that take advantage of wet years and can escape dry years as seeds. Our data support the conclusion that nutrient additions decrease the stability of productivity in both wet and arid grasslands. Nutrient enrichment increases the sensitivity of productivity to low rainfall years in wet grasslands, whereas nutrient enrichment in arid grasslands increases the sensitivity of productivity to high rainfall years. © 2017 by the Ecological Society of America.

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

    Science.gov (United States)

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

    2015-01-01

    SUMMARY 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 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 non-sprouting shrub species considered. Functional diversity 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 (r2=0.63). Functional diversity also improved the resistance of multifunctionality along the aridity gradient studied. Maintaining and enhancing functional diversity in plant communities may help to buffer negative effects of ongoing global environmental change on dryland multifunctionality. PMID:25615801

  5. Ecology and functional roles of biological soil crusts in semi-arid ecosystems of Spain

    Science.gov (United States)

    Maestre, Fernando T.; Bowker, Matthew A.; Cantón, Yolanda; Castillo-Monroy, Andrea P.; Cortina, Jordi; Escolar, Cristina; Escudero, Adrián; Lázaro, Roberto; Martínez, Isabel

    2015-01-01

    Biological soil crusts (BSCs), composed of lichens, cyanobacteria, mosses, liverworts and microorganisms, are key biotic components of arid and semi-arid ecosystems worldwide. Despite they are widespread in Spain, these organisms have been historically understudied in this country. This trend is beginning to change as a recent wave of research has been identifying BSCs as a model ecological system. Many studies and research projects carried out in Spain have explored the role of BSCs on water, carbon and nitrogen fluxes, the interactions between BSCs and vascular plants, their dynamics after disturbances, and their response to global change, among other topics. In this article we review the growing body of research on BSCs available from semi-arid areas of Spain, highlighting its importance for increasing our knowledge on this group of organisms. We also discuss how it is breaking new ground in emerging research areas on the ecology of BSCs, and how it can be use to guide management and restoration efforts. Finally, we provide directions for future research on the ecology of BSCs in Spain and abroad. PMID:25908884

  6. Sustainability of Water Resources in Arid Ecosystems: A View from Hei River Basin, China (Invited)

    Science.gov (United States)

    Zheng, C.; Cheng, G.; Xiao, H.; Ma, R.

    2009-12-01

    The northwest of China is characterized by an arid climate and fragile ecosystems. With irrigated agriculture, the region is a prolific producer of cotton, wheat, and maize with some of the highest output per acre in the country. The region is also rich in ore deposits, with the reserves of numerous minerals ranked at or near the top in the country. However, the sustainability of irrigated agriculture and economic development in the region is threaten by severe eco-environmental problems resulting from both global changes and human activities, such as desertification, salinization, groundwater depletion, and dust storms. All these problems are a direct consequence of water scarcity. As global warming accelerates and rapid economic growth continues, the water shortage crisis is expected to worsen. To improve the bleak outlook for the health of ecosystem and environment in northwest China, the Chinese government has invested heavily in ecosystem restoration and watershed management in recent years. However, the effectiveness of such measures and actions depends on scientific understanding of the complex interplays among ecological, hydrological and socioeconomic factors. This presentation is intended to provide an overview of a major new research initiative supported by the National Natural Science Foundation of China to study the integration of ecological principles, hydrological processes and socioeconomic considerations toward more sustainable exploitation of surface water and groundwater resources in the Hei River Basin in northwest China. The Hei River Basin is an inland watershed located at the center of the arid region in East Asia, stretching from Qilianshan Mountains in the south to the desert in the north bordering China’s Inner Mongolia Autonomous Region and Mongolia. The total area of Hei River Basin is approximately 130,000 km2. The research initiative builds on existing research infrastructure and ecohydrological data and seeks to reveal complex

  7. The use of spatial empirical models to estimate soil erosion in arid ecosystems.

    Science.gov (United States)

    Abdullah, Meshal; Feagin, Rusty; Musawi, Layla

    2017-02-01

    The central objective of this project was to utilize geographical information systems and remote sensing to compare soil erosion models, including Modified Pacific South-west Inter Agency Committee (MPSIAC), Erosion Potential Method (EPM), and Revised Universal Soil Loss Equation (RUSLE), and to determine their applicability for arid regions such as Kuwait. The northern portion of Umm Nigga, containing both coastal and desert ecosystems, falls within the boundaries of the de-militarized zone (DMZ) adjacent to Iraq and has been fenced off to restrict public access since 1994. Results showed that the MPSIAC and EPM models were similar in spatial distribution of erosion, though the MPSIAC had a more realistic spatial distribution of erosion and presented finer level details. The RUSLE presented unrealistic results. We then predicted the amount of soil loss between coastal and desert areas and fenced and unfenced sites for each model. In the MPSIAC and EPM models, soil loss was different between fenced and unfenced sites at the desert areas, which was higher at the unfenced due to the low vegetation cover. The overall results implied that vegetation cover played an important role in reducing soil erosion and that fencing is much more important in the desert ecosystems to protect against human activities such as overgrazing. We conclude that the MPSIAC model is best for predicting soil erosion for arid regions such as Kuwait. We also recommend the integration of field-based experiments with lab-based spatial analysis and modeling in future research.

  8. Photodegradation processes in arid ecosystems: controlling factors and potential application in land restoration

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Luna-Ramos, Lourdes; Oyonarte, Cecilio; Sole Benet, Albert

    2017-04-01

    Water availability plays a fundamental part in controlling biotic processes in arid ecosystems. However, recent evidence suggests that other decisive drivers take part in these processes. Despite low annual rainfall and microbial activity, unexplained high rates of litter decomposition, net nitrogen mineralization, soil enzymatic activity and carbon turnover have been observed in arid ecosystems. These observations have been partly explained by photodegradation, a process that consists of the breakdown of organic matter via solar radiation (UV) and that can increase decomposition rates and lead to changes in the balance of carbon and nutrients between plants, soil and atmosphere. A complete understanding of these mechanisms and its drivers in arid ecosystems remains a critical challenge for the scientific community at the global level. In this research, we conducted a multi-site field experiment to test the effects of photodegradation on decomposition of organic amendments used in ecosystem restoration. The study was carried out during 12 months in two study areas: the Pilbara region in Western Australia (Southern Hemisphere) and the Cabo de Gata Nijar Natural Park, South Spain (Northern Hemisphere). In both sites, four treatments were applied in replicated plots (1x1 m, n=4) that included a control (C) with no soil amendment; organic amendment covering the soil surface (AS); organic amendment incorporated into the soil (AI); and a combination of both techniques, both covering the surface and incorporated into the soil (AS-AI). Different organic amendments (native mulch versus compost) and soil substrates were used at each site according to local practices, but in both sites these were applied to increase soil organic matter up to 2%. At the two locations, a radiometer and a logger with a soil temperature and soil moisture probe were installed to monitor UV radiation and soil conditions for the duration of the trial. Soil microbial activity, soil CO2 efflux, and

  9. Deriving seasonal dynamics in ecosystem properties of semi-arid savanna grasslands from in situ-based hyperspectral reflectance

    DEFF Research Database (Denmark)

    Tagesson, Håkan Torbern; Fensholt, Rasmus; Huber, S.

    2015-01-01

    This paper investigates how hyperspectral reflectance (between 350 and 1800 nm) can be used to infer ecosystem properties for a semi-arid savanna grassland in West Africa using a unique in situ-based multi-angular data set of hemispherical conical reflectance factor (HCRF) measurements. Relations......This paper investigates how hyperspectral reflectance (between 350 and 1800 nm) can be used to infer ecosystem properties for a semi-arid savanna grassland in West Africa using a unique in situ-based multi-angular data set of hemispherical conical reflectance factor (HCRF) measurements...

  10. Drivers of inter-annual variability in Net Ecosystem Exchange in a semi-arid savanna ecosystem, South Africa

    Directory of Open Access Journals (Sweden)

    S. A. Archibald

    2009-02-01

    Full Text Available Inter-annual variability in primary production and ecosystem respiration was explored using eddy-covariance data at a semi-arid savanna site in the Kruger Park, South Africa. New methods of extrapolating night-time respiration to the entire day and filling gaps in eddy-covariance data in semi-arid systems were developed. Net ecosystem exchange (NEE in these systems occurs as pulses associated with rainfall events, a pattern not well-represented in current standard gap-filling procedures developed primarily for temperate flux sites. They furthermore do not take into account the decrease in respiration at high soil temperatures. An artificial neural network (ANN model incorporating these features predicted measured fluxes accurately (MAE 0.42 gC/m2/day, and was able to represent the seasonal patterns of photosynthesis and respiration at the site. The amount of green leaf area (indexed using satellite-derived estimates of fractional interception of photosynthetically active radiation fAPAR, and the timing and magnitude of rainfall events, were the two most important predictors used in the ANN model. These drivers were also identified by multiple linear regressions (MLR, with strong interactive effects. The annual integral of the filled NEE data was found to range from −138 to +155 g C/m2/y over the 5 year eddy covariance measurement period. When applied to a 25 year time series of meteorological data, the ANN model predicts an annual mean NEE of 75(±105 g C/m2/y. The main correlates of this inter-annual variability were found to be variation in the amount of absorbed photosynthetically active radiation (APAR, length of the growing season, and number of days in the year when moisture was available in the soil.

  11. New Possibilities for High-Resolution, Large-Scale Ecosystem Assessment of the World's Semi-Arid Regions

    Science.gov (United States)

    Burney, J. A.; Goldblatt, R.

    2016-12-01

    Understanding drivers of land use change - and in particular, levels of ecosystem degradation - in semi-arid regions is of critical importance because these agroecosystems (1) are home to the world's poorest populations, almost all of whom depend on agriculture for their livelihoods, (2) play a critical role in the global carbon and climate cycles, and (3) have in many cases seen dramatic changes in temperature and precipitation, relative to global averages, over the past several decades. However, assessing ecosystem health (or, conversely, degradation) presents a difficult measurement problem. Established methods are very labor intensive and rest on detailed questionnaires and field assessments. High-resolution satellite imagery has a unique role semi-arid ecosystem assessment in that it can be used for rapid (or repeated) and very simple measurements of tree and shrub density, an excellent overall indicator for dryland ecosystem health. Because trees and large shrubs are more sparse in semi-arid regions, sub-meter resolution imagery in conjunction with automated image analysis can be used to assess density differences at high spatial resolution without expensive and time-consuming ground-truthing. This could be used down to the farm level, for example, to better assess the larger-scale ecosystem impacts of different management practices, to assess compliance with REDD+ carbon offset protocols, or to evaluate implementation of conservation goals. Here we present results comparing spatial and spectral remote sensing methods for semi-arid ecosystem assessment across new data sources, using the Brazilian Sertão as an example, and the implications for large-scale use in semi-arid ecosystem science.

  12. Response of arid ecosystems to the Holocene climate variability along west and central Mediterranean gradients.

    Science.gov (United States)

    Jaouadi, Sahbi; Combourieu Nebout, Nathalie; Azuara, Julien; Lebreton, Vincent

    2017-04-01

    Decadal to millennial climate variability is a common feature recorded by environmental series. However interconnections between climate forcing (i.e. insolation, thermohaline circulation) and large atmospheric circulation patterns (i.e. North Atlantic Oscillation, Mediterranean Oscillation, Monsoon) still remain poorly understood considering their respective impacts on the global climate mechanisms. In the Mediterranean area, joint climatic influences from high temperate and low subtropical latitudes result in a high sensitivity of ecosystems to climate changes and especially to extreme events. Several vegetation records illustrate millennial changes in Mediterranean. Nevertheless notable discrepancies in the environmental response arise between Mediterranean edges (east vs west, north vs south). The new paleoenvironmental record from Sebkha Boujmel (33°N, southern Tunisia) covers the last 8kyr and exhibits eight humid/arid fluctuations with cyclic expansion of the desert, related to Middle and Late Holocene rapid climate changes (RCC) occurring at a centennial scale. Sebkha Boujmel record is replaced in the wider context of west Mediterranean and northern hemisphere. Asynchronies and disparity of the Mediterranean RCC occurrence documents north-south and west-east climate gradients in the west Mediterranean and pinpoint Sebkha Boujmel as the single vegetation record tracing as many climate events during the last 8kyr. Indeed the high sensitivity of arid environments triggers the prompt reaction of the southern Tunisian vegetation to Holocene RCC however tenuous. Pattern of RCC geographical occurrence in west and central Mediterranean is interpreted in the light of climate forcings involved for the Holocene centennial variability.

  13. Crop production and economic loss due to wind erosion in hot arid ecosystem of India

    Science.gov (United States)

    Santra, Priyabrata; Moharana, P. C.; Kumar, Mahesh; Soni, M. L.; Pandey, C. B.; Chaudhari, S. K.; Sikka, A. K.

    2017-10-01

    Wind erosion is a severe land degradation process in hot arid western India and affects the agricultural production system. It affects crop yield directly by damaging the crops through abrasion, burial, dust deposition etc. and indirectly by reducing soil fertility. In this study, an attempt was made to quantify the indirect impact of wind erosion process on crop production loss and associated economic loss in hot arid ecosystem of India. It has been observed that soil loss due to wind erosion varies from minimum 1.3 t ha-1 to maximum 83.3 t ha-1 as per the severity. Yield loss due to wind erosion was found maximum for groundnut (Arachis hypogea) (5-331 kg ha-1 yr-1), whereas minimum for moth bean (Vigna aconitifolia) (1-93 kg ha-1 yr-1). For pearl millet (Pennisetum glaucum), which covers a major portion of arable lands in western Rajasthan, the yield loss was found 3-195 kg ha-1 yr-1. Economic loss was found higher for groundnut and clusterbean (Cyamopsis tetragonoloba) than rest crops, which are about

  14. Ecosystem Services Evaluation and Its Spatial Characteristics in Central Asia’s Arid Regions: A Case Study in Altay Prefecture, China

    Directory of Open Access Journals (Sweden)

    Qi Fu

    2015-06-01

    Full Text Available Ecosystem services are important foundations to realize the sustainable development of economy and society. The question of how to quantitatively evaluate ecosystem services in a scientific way is a hot topic among international researchers. Studying the spatial characteristics of ecosystem services in arid regions can provide the theoretical and practical basis for coordinating a sustainable man-land relationship. Altay Prefecture of China, a typical arid region in Central Asia, was taken as the study area. It is on the Silk Road economic belt, which is a key region in the program of developing Western China. Three ecosystem services: water yield, soil conservation, and net primary productivity were quantitatively evaluated. The results show that (1 the spatial distribution pattern has a distinct characteristic of zonality; (2 mountain zone and mountain-oasis ecotone are the hotspots of ecosystem services; and (3 the correlation between water yield and net primary productivity shows a gradual increasing trend as altitude decreases. Objective analysis from the aspect of mechanism is given by discussing the causes of this particular pattern. It is found that altitude and slope have great influence on spatial distributions of ecosystem services, zones with the most amount of services are distributed in 1.5–2 km-altitude and 15–25°-slope. Different human activities in different regions and spatial distance decay of ecosystem services also contribute to the formation of spatial pattern. Thus, overgrazing, logging and mining are prohibited in mountain zones and mountain-oasis ecotones. Scholars are encouraged to focus on desert-ecosystem services in the future.

  15. 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

  16. Effect of rhizobacterial consortia from undisturbed arid- and agro-ecosystems on wheat growth under different conditions.

    Science.gov (United States)

    Inostroza, N G; Barra, P J; Wick, L Y; Mora, M L; Jorquera, M A

    2017-02-01

    Plant growth-promoting rhizobacteria (PGPR) are studied as complements/alternatives to chemical fertilizers used in agriculture. However, poor information exists on the potential of PGPR from undisturbed ecosystems. Here, we have evaluated the plant growth-promoting (PGP) effect of rhizobacterial consortia from undisturbed Chilean arid ecosystems (Consortium C1) and agro-ecosystems (Consortium C2) on plant biomass production. The PGP effects of C1 and C2 were assayed in wheat seedlings (Triticum aestivum L.) grown in pots under growth chamber conditions and in pots placed in an open greenhouse under natural conditions, using two different Chilean Andisols (Piedras Negras and Freire series) kept either at 30 or 60% of their maximum water holding capacity (MWHC). PGP effects depended on the soil type, MWHC and the growth conditions tested. Although both consortia showed PGB effects in artificial soils relative to controls in growth chambers, only C1 provoked a PGP effect at 60% MWHC in phosphorus-poor soil of the 'Piedras Negras' series. At natural conditions, however, only C1 exhibited statistically significant PGP effects at 30% MWHC in 'Piedras Negras', yet and most importantly allowed to maintain similar plant biomass as at 60% MWHC. Our results support possible applications of rhizobacterial consortia from arid ecosystems to improve wheat growth in Chilean Andisols under water shortage conditions. Wheat seedling inoculated with rhizobacterial consortia obtained from an undisturbed Chilean arid ecosystem showed improved growth in phosphorus-poor and partly dry soil. Arid ecosystems should be considered in further studies as an alternative source of microbial inoculants for agro-ecosystems subjected to stressful conditions by low nutrients and/or adverse climate events. © 2016 The Society for Applied Microbiology.

  17. FAUNA OF COLEPTERA,TENEBRIORIDAE OF ARID COASTAL AND ISLAND ECOSYSTEMS OF THE CASPIAN SEA.

    Directory of Open Access Journals (Sweden)

    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.

  18. The active microbial diversity drives ecosystem multifunctionality and is physiologically related to carbon availability in Mediterranean semi-arid soils.

    Science.gov (United States)

    Bastida, Felipe; Torres, Irene F; Moreno, José L; Baldrian, Petr; Ondoño, Sara; Ruiz-Navarro, Antonio; Hernández, Teresa; Richnow, Hans H; Starke, Robert; García, Carlos; Jehmlich, Nico

    2016-09-01

    Biogeochemical processes and ecosystemic functions are mostly driven by soil microbial communities. However, most methods focus on evaluating the total microbial community and fail to discriminate its active fraction which is linked to soil functionality. Precisely, the activity of the microbial community is strongly limited by the availability of organic carbon (C) in soils under arid and semi-arid climate. Here, we provide a complementary genomic and metaproteomic approach to investigate the relationships between the diversity of the total community, the active diversity and ecosystem functionality across a dissolved organic carbon (DOC) gradient in southeast Spain. DOC correlated with the ecosystem multifunctionality index composed by soil respiration, enzyme activities (urease, alkaline phosphatase and β-glucosidase) and microbial biomass (phospholipid fatty acids, PLFA). This study highlights that the active diversity (determined by metaprotoemics) but not the diversity of the whole microbial community (evaluated by amplicon gene sequencing) is related to the availability of organic C and it is also connected to the ecosystem multifunctionality index. We reveal that DOC shapes the activities of bacterial and fungal populations in Mediterranean semi-arid soils and determines the compartmentalization of functional niches. For instance, Rhizobales thrived at high-DOC sites probably fuelled by metabolism of one-C compounds. Moreover, the analysis of proteins involved in the transport and metabolism of carbohydrates revealed that Ascomycota and Basidiomycota occupied different nutritional niches. The functional mechanisms for niche specialization were not constant across the DOC gradient. © 2016 John Wiley & Sons Ltd.

  19. Desert Affairs Program: An initiative on integrating research, education and application for sustainable development in arid and semi-arid lands

    Science.gov (United States)

    Ye, Qian; Glantz, Michael H.; Pan, Xiaoling; Gao, Wei; Ma, Yingjun

    2003-07-01

    By recognizing the issues related with drought, desertification, diversity and development (i.e., the 4Ds) in arid and semi-arid lands in Central and Western Asia, The need of developing an interdisciplinary and environment-oriented education and training program, named "Desert Affairs Program", is discussed. Its aim is to train present and future researchers, policymakers and educators for dealing with issues related to environmental science, impacts, policy, economy and ethics in arid and semi-arid lands in Central and Western Asia.

  20. 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.

  1. 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.

  2. Impact of seasonal changes on fungal diversity of a semi-arid ecosystem revealed by 454 pyrosequencing.

    Science.gov (United States)

    Vargas-Gastélum, Lluvia; Romero-Olivares, Adriana L; Escalante, Ana E; Rocha-Olivares, Axayácatl; Brizuela, Carlos; Riquelme, Meritxell

    2015-05-01

    Fungi play fundamental ecological roles in terrestrial ecosystems. However, their distribution and diversity remain poorly described in natural communities, particularly in arid and semi-arid ecosystems. In order to identify environmental factors determining fungal community structure in these systems, we assessed their diversity in conjunction with soil physicochemical characteristics in a semi-arid ecosystem in Baja California, Mexico, endemic for Coccidioidomycosis (Valley Fever). Two different microhabitats, burrows (influenced by rodent activity) and topsoil, were compared in winter and summer. Using a metagenomic approach, the ITS1 region of nuclear ribosomal DNA was used as barcode. A total of 1940 Operational Taxonomic Units (OTUs) were identified from 362 332 ITS1 sequences obtained by 454 pyrosequencing. Differences in fungal composition between seasons were clearly identified. Moreover, differences in composition between microhabitats were mainly correlated to significant differences in environmental factors, such as moisture and clay content in topsoil samples, and temperature and electrical conductivity in burrow samples. Overall, the fungal community structure (dominated by Ascomycota and Basidiomycota) was less variable between seasons in burrow than in topsoil samples. Coccidioides spp. went undetected by pyrosequencing. However, a nested PCR approach revealed its higher prevalence in burrows. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  3. Alternative pathways to landscape transformation: Invasive grasses, burn severity and fire frequency in arid ecosystems

    Science.gov (United States)

    Klinger, Robert C.; Brooks, Matthew L.

    2017-01-01

    Arid ecosystems are often vulnerable to transformation to invasive-dominated states following fire, but data on persistence of these states are sparse. The grass/fire cycle is a feedback process between invasive annual grasses and fire frequency that often leads to the formation of alternative vegetation states dominated by the invasive grasses. However, other components of fire regimes, such as burn severity, also have the potential to produce long-term vegetation transformations. Our goal was to evaluate the influence of both fire frequency and burn severity on the transformation of woody-dominated communities to communities dominated by invasive grasses in major elevation zones of the Mojave Desert of western North America.We used a chronosequence design to collect data on herbaceous and woody cover at 229 unburned reference plots and 578 plots that burned between 1972 and 2010. We stratified the plots by elevation zone (low, mid, high), fire frequency (1–3 times) and years post-fire (YPF; 1–5, 6–10, 11–20 and 21–40 YPF). Burn severity for each plot was estimated by the difference normalized burn ratio.We identified two broad post-fire successional pathways. One was an outcome of fire frequency, resulting in a strong potential transformation via the grass/fire cycle. The second pathway was driven by burn severity, the critical aspect being that long-term transformation of a community could occur from just one fire in areas that burned at high or sometimes moderate severity. Dominance by invasive grasses was most likely to occur in low-and high-elevation communities; cover of native herbaceous species was often greater than that of invasive grasses in the mid-elevation zone.Synthesis. Invasive grasses can dominate a site that burned only one time in many decades at high severity, or a site that burned at low severity but multiple times in the same time period. However, high burn severity may predispose areas to more frequent fire because they have

  4. The effect of increased temperature and altered precipitation on plants in an arid ecosystem

    Science.gov (United States)

    Wertin, T. M.; Reed, S.; Belnap, J.

    2011-12-01

    Projected changes in climate are expected to strongly affect arid and semi-arid landscapes where plant communities are assumed to already experience high temperatures and low water availability. Here we investigated the effect of elevated temperature and altered precipitation regimes on plant physiology, community composition, phenology and growth on the Colorado Plateau. The ecosystem is dominated by the native perennial grasses Pleuraphis jamesii and Achnatherum hymenoides and the shrub Atriplex confertifolia and has well-formed biological soil crusts. The invasive annual grass Bromus tectorum is also present. In 2005, five blocks of four 2m by 2.5m plots were established, and within each block plots were randomly assigned to ambient or elevated temperature (soil surface temperature of +2°C above ambient) and ambient or elevated precipitation (1.5 mm precipitation pulses applied three times weekly during summer) in full-factorial. In 2009 the temperature treatment was increased to +4°C. Additionally, five new blocks were established with the plots randomly assigned ambient or elevated temperature (again, +2°C was used) and ambient or elevated precipitation (summertime large bi-weekly watering to counteract negative effects the lamps may have had on soil moisture) in full-factorial. Throughout 2010 and 2011 the phenological state of the dominate plant species was recorded weekly. At the end of May 2010 and 2011 biomass accumulation, reproductive output and vegetative cover were assessed. Additionally, diurnal foliar gas exchange, foliar fluorescence and xylem pressure potential were measured on the dominant plant species three times throughout the spring and summer of 2011. Elevated temperature had no effect on carbon fixation or foliar physiology of A. confertifolia or P. jamesii, though A. hymenoides carbon fixation was negatively affected by elevated temperature with the +4°C treatment causing a greater reduction in fixation than the +2°C treatment. The

  5. Linking the spatial patterns of organisms and abiotic factors to ecosystem function and management: insights from semi-arid environments

    Directory of Open Access Journals (Sweden)

    F. T. Maestre

    2006-12-01

    Full Text Available Numerous theoretical and modeling studies have demonstrated the ecological significance of the spatial patterning of organisms on ecosystem functioning and dynamics. However, there is a paucity of empirical evidence that quantitatively shows how changes in the spatial patterns of the organisms forming biotic communities are directly related to ecosystem structure and functioning. In this article, I review a series of experiments and observational studies conducted in semi-arid environments from Spain (degraded calcareous shrubland, steppes dominated by Stipa tenacissima, and gypsum shrublands to: 1 evaluate whether the spatial patterns of the dominant biotic elements in the community are linked to ecosystem structure and functioning, and 2 test if these patterns, and those of abiotic factors, can be used to improve ecosystem restoration. In the semiarid steppes we found a significant positive relationship between the spatial pattern of the perennial plant community and: i the water status of S. tenacissima and ii perennial species richness and diversity. Experimental plantings conducted in these steppes showed that S. tenacissima facilitated the establishment of shrub seedlings, albeit the magnitude and direction of this effect was dependent on rainfall conditions during the first yr after planting. In the gypsum shrubland, a significant, direct relationship between the spatial pattern of the biological soil crusts and surrogates of ecosystem functioning (soil bulk density and respiration was found. In a degraded shrubland with very low vegetation cover, the survival of an introduced population of the shrub Pistacia lentiscus showed marked spatial patterns, which were related to the spatial patterns of soil properties such as soil compaction and sand content. These results provide empirical evidence on the importance of spatial patterns for maintaining ecosystem structure and functioning in semi-arid ecosystems

  6. Nitrogen cycling: water use efficiency interactions in semi-arid ecosystems in relation to management of tree legumes (Prosopis)

    Energy Technology Data Exchange (ETDEWEB)

    Felker, P.; Clark, P.R.; Osborn, J.; Cannell, G.H.

    1980-04-01

    Plant productivity in semi-arid ecosystems is often limited by soil fertility as much as it is by moisture availability. A quantitative assessment of nitrogen limitations on water use efficiency has been made after careful review of plant water use efficiency data at high and low soil fertilities and after careful review of nitrogen inputs to semi arid ecosystems in the form of: blue-green algae-lichen crusts; non-symbiotic nitrogen fixers; rainfall; and tree legumes. This analysis indicates that plant productivity in semi-arid regions may be 10 fold more limited by nitrogen than moisture availability. Forage yields of non-nitrogen fixing trees and shrubs could be greatly increased by interplanting with drought adapted nitrogen fixers such as Prosopis and Acacia. Calculations based on water use efficiencies of annual legumes and nitrogen fixation values of tree legumes predict that well managed, spaced, and cared for orchards of specially selected Prosopis could produce 4000 Kgha/sup -1/ yr/sup -1/ of 13% protein pods at 500 mm annual rainfall with only light fertilization with phosphate, potassium and sulfur. Field measurements of pod yields for 25 selections of 3 year old Prosopis grown under managed orchard conditions in southern California are presented. Spacing regimes and harvesting techniques for Prosopis are proposed to facilitate pod production.

  7. Quantifying the sensitivity of ephemeral streams to land disturbance activities in arid ecosystems at the watershed scale

    Energy Technology Data Exchange (ETDEWEB)

    O’Connor, Ben L.; Hamada, Yuki; Bowen, Esther E.; Grippo, Mark A.; Hartmann, Heidi M.; Patton, Terri L.; Van Lonkhuyzen, Robert A.; Carr, Adrianne E.

    2014-08-17

    Large areas of public lands administered by the Bureau of Land Management and located in arid regions of the southwestern United States are being considered for the development of utility-scale solar energy facilities. Land-disturbing activities in these desert, alluvium-filled valleys have the potential to adversely affect the hydrologic and ecologic functions of ephemeral streams. Regulation and management of ephemeral streams typically falls under a spectrum of federal, state, and local programs, but scientifically based guidelines for protecting ephemeral streams with respect to land-development activities are largely nonexistent. This study developed an assessment approach for quantifying the sensitivity to land disturbance of ephemeral stream reaches located in proposed solar energy zones (SEZs). The ephemeral stream assessment approach used publicly-available geospatial data on hydrology, topography, surficial geology, and soil characteristics, as well as highresolution aerial imagery. These datasets were used to inform a professional judgment-based score index of potential land disturbance impacts on selected critical functions of ephemeral streams, including flow and sediment conveyance, ecological habitat value, and groundwater recharge. The total sensitivity scores (sum of scores for the critical stream functions of flow and sediment conveyance, ecological habitats, and groundwater recharge) were used to identify highly sensitive stream reaches to inform decisions on developable areas in SEZs. Total sensitivity scores typically reflected the scores of the individual stream functions; some exceptions pertain to groundwater recharge and ecological habitats. The primary limitations of this assessment approach were the lack of high-resolution identification of ephemeral stream channels in the existing National Hydrography Dataset, and the lack of mechanistic processes describing potential impacts on ephemeral stream functions at the watershed scale

  8. Program on ecosystem change and society

    DEFF Research Database (Denmark)

    Carpenter, Stephen R.; Folke, Carl; Norström, Albert

    2012-01-01

    The Program on Ecosystem Change and Society (PECS), a new initiative within the ICSU global change programs, aims to integrate research on the stewardship of social-ecological systems, the services they generate, and the relationships among natural capital, human wellbeing, livelihoods, inequalit...

  9. Carbon-cycle implications of asymmetry in response of semi-arid ecosystem phenology and productivity to rainfall

    Science.gov (United States)

    Smith, Benjamin; Haverd, Vanessa; Ahlström, Anders; Canadell, Josep

    2017-04-01

    Semi-arid savannahs and shrublands of the tropics and subtropics play a key role in the inter-annual variability of the global carbon cycle and are emerging as an important player - comparable with tropical forests - in terms of their contribution to the ongoing sink trend of the carbon exchange between the global land surface and atmosphere. Both the variability and carbon balance trend of the savannah-shrubland biome are characterised by shifting phenology, mediated by changes in the seasonality and relative contributions to ecosystem productivity of woody vegetation elements and grasses. Shifts in water availability associated with the impacts of global circulation systems on the distribution and amount of rainfall are a key driver of vegetation response in these ecosystems, which tolerate drought, but spring to life, becoming highly productive, during episodes of ample water supply. This "boom or bust" behaviour with respect to water availability may be expected to translate into an asymmetric response to rainfall change, positive anomalies in rainfall tending to lead to larger increases in productivity compared with the corresponding decrease in productivity resulting from a negative anomaly of comparable size. As rainfall distributions over time themselves exhibit asymmetry, an 'intrinsic' (ecosystem response-driven) and 'extrinsic' (climate or weather forcing-driven) component of asymmetry may be distinguished. We investigated the prevalence of asymmetry in forcing and response of ecosystem productivity to rainfall variability globally and for the illustrative case of Australia, which emerges as a global 'hot spot' for rainfall-driven variability in ecosystem gross primary production (GPP) and associated net ecosystem productivity (NEP). Employing two climate-driven ecosystem models, informed by multiple observation types (land-atmosphere fluxes, biomass, streamflow and remotely-sensed vegetation cover), we show that the inland region of Australia, dominated

  10. Evapotranspiration and soil water relationships in a range of disturbed and undisturbed ecosystems in the semi-arid Inner Mongolia, China

    Science.gov (United States)

    Nan Lu; Shiping Chen; Burkhard Wilske; Ge Sun; Jiquan Chen

    2011-01-01

    Aims: Evapotranspiration (ET) is a key component of water balance and is closely linked to ecosystem productivity. In arid regions, large proportion of precipitation (PPT) is returned to the atmosphere through ET, with only a small amount available to plants. Our objective was to examine the variability in ET–soil water relationship based on a set of ecosystems that...

  11. Integrating phenology and patterns in spatial autocorrelation to delineate perennial grass cover using Landsat: A case study in a southwestern U.S. arid ecosystem

    Science.gov (United States)

    The presence and persistence of perennial grasses are important indicators for ecosystem function, biodiversity, and sustainable land management practices worldwide. Reliably distinguishing the perennial grass cover is challenging; this is especially true in arid ecosystems in the southwestern U.S. ...

  12. Water Scarcity, Food Insecurity and Drought Induced Displacement in an Arid Ecosystem: A Case Study in Indian Desert

    Science.gov (United States)

    Rehman Siddiqui, Azizur

    2017-04-01

    Indian Arid Ecosystem is characterised by scare as well as seasonal precipitation that have led to long term stress in a fragile ecosystem. In addition to this, over the years, Indian desert has experienced varying magnitude of drought, which have considerably influenced food and fodder production and led to the depletion of surface and ground water table. All these factors mean that the production potential of land is hardly sufficient to feed human as well as livestock population of the desert and this has led to extensive rural to urban migration in Indian Desert. In the present study, satellite data from Landsat TM, AWiFS, NOAA AVHRR have been used to detect the intensity and severity of drought condition, and data collected through primary survey has been used to measure the impact of water scarcity on food insecurity and drought induced migration. Rainfall trend analysis of the study area has been done with the help of Man Kendall Method to assess the meteorological vulnerability. In addition to these, NDVI, VCI, TCI, and VHI have also been used to find out the long term vegetation health in the study area. With the help of these scientific techniques, the paper focuses on the moisture deficiency during growing period and its effect on human population and livestock population. Keywords: Arid Ecosystem, Indian Desert, Drought, Migration

  13. Drought dominates the interannual variability in global terrestrial net primary production by controlling semi-arid ecosystems.

    Science.gov (United States)

    Huang, Ling; He, Bin; Chen, Aifang; Wang, Haiyan; Liu, Junjie; Lű, Aifeng; Chen, Ziyue

    2016-04-19

    Drought is a main driver of interannual variation in global terrestrial net primary production. However, how and to what extent drought impacts global NPP variability is unclear. Based on the multi-timescale drought index SPEI and a satellite-based annual global terrestrial NPP dataset, we observed a robust relationship between drought and NPP in both hemispheres. In the Northern Hemisphere, the annual NPP trend is driven by 19-month drought variation, whereas that in the Southern Hemisphere is driven by 16-month drought variation. Drought-dominated NPP, which mainly occurs in semi-arid ecosystems, explains 29% of the interannual variation in global NPP, despite its 16% contribution to total global NPP. More surprisingly, drought prone ecosystems in the Southern Hemisphere, which only account for 7% of the total global NPP, contribute to 33% of the interannual variation in global NPP. Our observations support the leading role of semi-arid ecosystems in interannual variability in global NPP and highlight the great impacts of long-term drought on the global carbon cycle.

  14. Slope aspect influences arbuscular mycorrhizal fungus communities in arid ecosystems of the Daqingshan Mountains, Inner Mongolia, North China.

    Science.gov (United States)

    Liu, Min; Zheng, Rong; Bai, Shulan; Bai, Yv E; Wang, Jugang

    2017-04-01

    Arbuscular mycorrhizal (AM) symbiosis plays an important role in ecosystem functioning, particularly in fragile environments. Little is known, however, about how AM fungus community composition responds to slope aspect. Our objective was to compare the AM fungus communities between sunny and shady slopes and to detect factors that influenced the distributions of AM fungi in arid ecosystems of the Daqingshan Mountains, Inner Mongolia, North China. AM fungus communities were evaluated based on small subunit ribosomal RNA genes (SSUs) using Illumina MiSeq sequencing. AM fungus community composition differed significantly between slope aspects, and sunny slopes had significantly higher AM fungus diversity and richness as well as spore density, total root colonization, arbuscule abundance, vesicle abundance, and hyphal colonization than shady slopes. Structural equation modeling (SEM) illustrated that the effects of slope aspect on AM fungus richness likely were mediated by available phosphorus, soil organic carbon, plant cover, and plant diversity. Available phosphorus was the principal factor that influenced AM fungus species richness, and soil organic carbon was the principal factor influencing spore density and total root colonization, suggesting that these factors especially might be responsible for differences between the AM fungus communities of different slope aspects. These findings elucidate the influence of slope aspect on AM fungus communities and may inform use of AM fungi in protection and restoration of vegetation with different slope aspects in arid ecosystems.

  15. Assessment of Ecosystem Services in a Semi-arid Agriculture-dominant Area: Framework and Case Study

    Science.gov (United States)

    Dhungel, R.; Chen, Y.; Maltos, R.; Sivakumaran, K.; Aguilar, A.; Harmon, T. C.

    2015-12-01

    California's Central Valley (CV) water crisis has increased in severity due to a prolonged drought. The drought is directly contributing to the overexploitation of groundwater, along with deficiency in agricultural, recreational and aesthetic water services. The population of the CV, home to about 6.5 million people, is projected to be 12 million by 2040. Balancing water demand between municipal use, agricultural supply, and other ecosystem services, will be challenging for this region in perpetuity. In the heart of CV lies the San Joaquin River (SJR) where Friant Dam is the main low-elevation reservoir regulating water release. The Friant Dam's reservoir fulfills agricultural, municipal and industrial water needs through the Friant-Kern and Madera canals, as well as through the mainstem SJR. The SJR restoration project (SJRRP) is a recent development that is imposing additional demands on water releases in order to restore sustainable aquatic habitat for Chinook salmon and other species on the mainstem below the Friant Dam. The Chinook require adequate flow to moderate river temperature, particularly during hot summer and fall months. Temperatures on CV rivers exhibit strong diurnal and seasonal patterns, and can rise to harmful levels when flows are inadequate. In this study, we developed a framework that allows for assessing the effectiveness and implied costs of ecosystem services provided by a restored SJR in a semi-arid agriculture-dominant area. This is done by explicitly linking economics-based farmers' model with a reduced-form hydrological model that is loosely coupled to a physical-based stream-temperature model, specifically CE-QUAL-W2. The farmers' model is based on positive mathematical program approach calibrated with twenty proxy crops for year 2005. The river-hydrology is simulated by a vector autoregression model that incorporates daily flow variability. We study the mandated release policies by the SJR restoration project, along with hypothetical

  16. Environmental resilience of rangeland ecosystems: assessment drought indices and vegetation trends on arid and semi-arid zones of Central Asia

    Science.gov (United States)

    Aralova, Dildora; Toderich, Kristina; Jarihani, Ben; Gafurov, Dilshod; Gismatulina, Liliya; Osunmadewa, Babatunde A.; Rahamtallah Abualgasim, Majdaldin

    2016-10-01

    The Central Asian (CA) rangelands is a part of the arid and semi-arid ecological zones and spatial extent of drylands in CA (Tajikistan, Kazakhstan, Uzbekistan, Kyrgyzstan, and Turkmenistan) is vast. Projections averaged across a suite of climate models, as measured between 1950-2012 by Standardised Precipitation-Evapotranspiration Index (SPEI) estimated a progressively increasing drought risks across rangelands (Turkmenistan, Tajikistan and Uzbekistan) especially during late summer and autumn periods, another index: Potential Evapotranspiration (PET) indicated drought anomalies for Turkmenistan and partly in Uzbekistan (between 1950-2000). On this study, we have combined a several datasets of drought indices ( SPIE, PET, temperature_T°C and precipitation_P) for better estimation of resilience/non-resilience of the ecosystems after warming the temperature in the following five countries, meanwhile, warming of climate causing of increasing rating of degradations and extension of desertification in the lowland and foothill zones of the landscape and consequently surrounding experienced of a raising balance of evapotranspiration (ET0). The study concluded, increasing drought anomalies which is closely related with raising (ET0) in the lowland and foothill zones of CA indicated on decreasing of NDVI indices with occurred sandy and loamy soils it will resulting a loss of vegetation diversity (endangered species) and raising of wind speeds in lowlands of CA, but on regional level especially towards agricultural intensification (without rotation) it indicated no changes of greenness index. It was investigated to better interpret how vegetation feedback modifies the sensitivity of drought indices associated with raising tendency of air temperature and changes of cold and hot year seasons length in the territory of CA.

  17. Net ecosystem production in the arid land in northwest China from 1982 to 2001

    Science.gov (United States)

    Chang, Shunli; Shi, Qingdong

    2009-06-01

    This study constructs a soil respiration model, which includes three variables: air temperature, precipitation and soil character using a semi-mechanistic-empirically statistical model by James W. Raich. The soil characteristics are variables introduced into the model in the study, including soil texture, soil depth, PH and soil organic carbon. Then the model was used to estimate the gross and illustrate spatial-temporal patterns of soil respiration based on the data obtained monthly across the arid land in northwest China from 1961 to 2001. The solar energy efficiency model was used to survey NPP, and the NEP on 20 years scale from 1982 to 2001. Thus, the following conclusions can be come up with: (1) from 1961 to 2001, the temperature and wetness had an increasing trend in the arid land in northwest China, while the range of precipitation variation was greater than before. Such climate change accelerated NPP and soil respiration, and declined NEP on a total level. The carbon sink function of arid land of Northwest China was weakening. (2) Under the background of increasing temperature and wetness, human cultivation accelerated soil respiration of the oasis. Thus, NEP of the oasis was declined. Thereby, the carbon sink function of oasis was weakening and soil degradation happened. 3) Moisture is a more important factor than temperature in the main processes of terrestrial carbon cycle in the arid areas in Northwest China. More attention should be paid to the precipitation in modeling dominant processes of the carbon cycle process in the arid areas.

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

    OpenAIRE

    Ogara OW; Boruru Ongoro

    2013-01-01

    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. T...

  19. Bridging structure and function in semi-arid ecosystems by integrating remote sensing and ground based measurements

    Science.gov (United States)

    Krofcheck, Dan J.

    The Southwestern US is projected to continue to experience a significant warming trend, with increased variability in the timing and magnitude of rainfall events. The effects of theses changes in climate are already manifesting in the form of expansive, prolonged 'megadroughts', which have resulted in the widespread mortality of woody vegetation across the region.Therefore the need to monitor and model forest mortality and carbon dynamics at the landscape and regional scale is an essential component of regional and global climate mitigation strategies, and critical if we are to understand how the imminent state transitions taking place in forests globally will affect climate forcing and feedbacks. Remote sensing offers the only solution to multitemporal regional observation, yet many challenges exist with employing modern remote sensing solutions in highly stressed vegetation characteristic of semi-arid biomes, making one of the most expansive biomes on the globe also one of the most difficult to accurately monitor and model. The goal of this research was to investigate how changes in the structure of semi-arid woodlands following forest mortality impacts ecosystem function, and address this question in the context of remote sensing data sets, thereby contributing to the remote sensing community's ability to interact with these challenging ecosystems. We first focused on pinus edulis and juniperous monosperma (pinon-juniper) woodlands, as they comprise a model semi-arid biome. We tested the ability of high resolution remote sensing data to mechanistically describe the patterns in overstory mortality and understory green-up, and were able to observe the heterogeneous response of the understory as a function of cover type. We also investigated the relationship between changes in soil water content and the greenness of the canopy, noting that in these stress ecosystems there is often a decoupling of the canopy as measured remotely (e.g., via vegetation indices, VI

  20. Woody plants in agro-ecosystems of semi-arid regions

    NARCIS (Netherlands)

    Breman, H.; Kessler, J.J.

    1995-01-01

    A quantitative analysis of the role of woody plants in semi-arid regions, focusing on the Sahel and Sudan zones in West-Africa, is given for the assessment of their benefits in agro-sylvopastoral land-use systems with productive and sustainability objectives.

  1. Very high CO2 exchange fluxes at the peak of the rainy season in a West African grazed semi-arid savanna ecosystem

    DEFF Research Database (Denmark)

    Tagesson, Håkan Torbern; Ardoe, Jonas; Guiro, Idrissa

    2016-01-01

    Africa is a sink of carbon, but there are large gaps in our knowledge regarding the CO2 exchange fluxes for many African ecosystems. Here, we analyse multi-annual eddy covariance data of CO2 exchange fluxes for a grazed Sahelian semi-arid savanna ecosystem in Senegal, West Africa. The aim...... to that of other semi-arid savanna sites due the short length of the rainy season. An inter-comparison between the open-path and a closed-path infrared sensor indicated no systematic errors related to the instrumentation. An uncertainty analysis of long-term NEE budgets indicated that corrections for air density...... response to climate change....

  2. Soil respiration dynamics in fire affected semi-arid ecosystems: Effects of vegetation type and environmental factors.

    Science.gov (United States)

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

    2016-12-01

    Soil respiration (Rs) is the second largest carbon flux in terrestrial ecosystems and therefore plays a crucial role in global carbon (C) cycling. This biogeochemical process is closely related to ecosystem productivity and soil fertility and is considered as a key indicator of soil health and quality reflecting the level of microbial activity. Wildfires can have a significant effect on Rs rates and the magnitude of the impacts will depend on environmental factors such as climate and vegetation, fire severity and meteorological conditions post-fire. In this research, we aimed to assess the impacts of a wildfire on the soil CO 2 fluxes and soil respiration in a semi-arid ecosystem of Western Australia, and to understand the main edaphic and environmental drivers controlling these fluxes for different vegetation types. Our results demonstrated increased rates of Rs in the burnt areas compared to the unburnt control sites, although these differences were highly dependent on the type of vegetation cover and time since fire. The sensitivity of Rs to temperature (Q10) was also larger in the burnt site compared to the control. Both Rs and soil organic C were consistently higher under Eucalyptus trees, followed by Acacia shrubs. Triodia grasses had the lowest Rs rates and C contents, which were similar to those found under bare soil patches. Regardless of the site condition (unburnt or burnt), Rs was triggered during periods of higher temperatures and water availability and environmental factors (temperature and moisture) could explain a large fraction of Rs variability, improving the relationship of moisture or temperature as single factors with Rs. This study demonstrates the importance of assessing CO 2 fluxes considering both abiotic factors and vegetation types after disturbances such as fire which is particularly important in heterogeneous semi-arid areas with patchy vegetation distribution where CO 2 fluxes can be largely underestimated. Copyright © 2016 Elsevier B

  3. Vulnerability of riparian ecosystems to elevated CO2 and climate change in arid and semiarid western North America

    Science.gov (United States)

    Perry, Laura G.; Andersen, Douglas C.; Reynolds, Lindsay V.; Nelson, S. Mark; Shafroth, Patrick B.

    2012-01-01

    Riparian ecosystems, already greatly altered by water management, land development, and biological invasion, are being further altered by increasing atmospheric CO2 concentrations ([CO2]) and climate change, particularly in arid and semiarid (dryland) regions. In this literature review, we (1) summarize expected changes in [CO2], climate, hydrology, and water management in dryland western North America, (2) consider likely effects of those changes on riparian ecosystems, and (3) identify critical knowledge gaps. Temperatures in the region are rising and droughts are becoming more frequent and intense. Warmer temperatures in turn are altering river hydrology: advancing the timing of spring snow melt floods, altering flood magnitudes, and reducing summer and base flows. Direct effects of increased [CO2] and climate change on riparian ecosystems may be similar to effects in uplands, including increased heat and water stress, altered phenology and species geographic distributions, and disrupted trophic and symbiotic interactions. Indirect effects due to climate-driven changes in streamflow, however, may exacerbate the direct effects of warming and increase the relative importance of moisture and fluvial disturbance as drivers of riparian ecosystem response to global change. Together, climate change and climate-driven changes in streamflow are likely to reduce abundance of dominant, native, early-successional tree species, favor herbaceous species and both drought-tolerant and late-successional woody species (including many introduced species), reduce habitat quality for many riparian animals, and slow litter decomposition and nutrient cycling. Climate-driven changes in human water demand and associated water management may intensify these effects. On some regulated rivers, however, reservoir releases could be managed to protect riparian ecosystem. Immediate research priorities include determining riparian species' environmental requirements and monitoring riparian

  4. Breaks in MODIS time series portend vegetation change: verification using long-term data in an arid grassland ecosystem.

    Science.gov (United States)

    Browning, Dawn M; Maynard, Jonathan J; Karl, Jason W; Peters, Debra C

    2017-07-01

    breaks accompanied changes in the contribution to biomass by perennial and/or annual grasses. The BFAST method using satellite imagery proved useful for detecting previously reported ground-based changes in vegetation in this arid ecosystem. We demonstrate that time series analysis of NDVI data holds potential for monitoring landscape condition in arid ecosystems at the large spatial scales needed to differentiate responses to a changing climate from responses to seasonal variability in rainfall. © 2017 by the Ecological Society of America.

  5. Burrowing herbivores alter soil carbon and nitrogen dynamics in a semi-arid ecosystem, Argentina

    Science.gov (United States)

    Kenneth L. Clark; Lyn C. Branch; Jose L. Hierro; Diego. Villarreal

    2016-01-01

    Activities of burrowing herbivores, including movement of soil and litter and deposition of waste material, can alter the distribution of labile carbon (C) and nitrogen (N) in soil, affecting spatial patterning of nutrient dynamics in ecosystems where they are abundant. Their role in ecosystem processes in surface soil has been studied extensively, but effects of...

  6. 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.

  7. Dependence of ecosystem respiration on soil temperature, moisture and plant biomass in a semi-arid grassland

    Science.gov (United States)

    Nakano, T.; Shinoda, M.

    2008-12-01

    The Mongolian steppe zone is one of the main components of central-Asian grasslands. Ecosystem respiration rates between the atmosphere and the steppe ecosystem were measured in a Mongolian semi- arid grassland in July 2004, May 2005, July 2005, September 2005, and June 2006 by using a closed- chamber technique. The study area is dominated by Poaceous grasses and was enclosed by a fence (300 m x 300 m) in June 2004 to prevent livestock from grazing. Along with the respiration measurements, soil temperature, precipitation, and soil volumetric water content were continuously measured. Aboveground plant biomass (AGB) was also determined by clipping vegetation for each observation period. From the measured data of ecosystem respiration and environmental variables, their quantitative relationships were examined. Individual rates of respiration showed the highest rank correlation coefficient with AGB. The correlation between respiration rate and soil moisture was higher at 3 cm depth than at 10 cm depth, which suggested that soil moisture near the soil surface was better proxy than that at deeper layer for accounting for variations in respiration rate. The respiration rate was exponentially related to the soil temperature and the relationship modified by soil moisture. The amount of respiration rate and its temperature sensitivity (Q10) declined with decreasing soil moisture. Standardized rates of respiration at 20°C were expressed well as a bivariate function of AGB and soil moisture at 3 cm depth. Approximately 88% of the fluctuation in standardized respiration rate was explained by the interaction of these two factors.

  8. Determining the relative importance of climatic drivers on spring phenology in grassland ecosystems of semi-arid areas

    Science.gov (United States)

    Zhu, Likai; Meng, Jijun

    2015-02-01

    Understanding climate controls on spring phenology in grassland ecosystems is critically important in predicting the impacts of future climate change on grassland productivity and carbon storage. The third-generation Global Inventory Monitoring and Modeling System (GIMMS3g) normalized difference vegetation index (NDVI) data were applied to derive the start of the growing season (SOS) from 1982-2010 in grassland ecosystems of Ordos, a typical semi-arid area in China. Then, the conditional Granger causality method was utilized to quantify the directed functional connectivity between key climatic drivers and the SOS. The results show that the asymmetric Gaussian (AG) function is better in reducing noise of NDVI time series than the double logistic (DL) function within our study area. The southeastern Ordos has earlier occurrence and lower variability of the SOS, whereas the northwestern Ordos has later occurrence and higher variability of the SOS. The research also reveals that spring precipitation has stronger causal connectivity with the SOS than other climatic factors over different grassland ecosystem types. There is no statistically significant trend across the study area, while the similar pattern is observed for spring precipitation. Our study highlights the link of spring phenology with different grassland types, and the use of coupling remote sensing and econometric tools. With the dramatic increase in global change research, Granger causality method augurs well for further development and application of time-series modeling of complex social-ecological systems at the intersection of remote sensing and landscape changes.

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

    Science.gov (United States)

    Ding, Guo-Chun; Piceno, Yvette M; Heuer, Holger; Weinert, Nicole; Dohrmann, Anja B; Carrillo, Angel; Andersen, Gary L; Castellanos, Thelma; Tebbe, Christoph C; Smalla, Kornelia

    2013-01-01

    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.

  10. 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.

  11. Understanding environmental drivers in the regulation of soil respiration dynamics after fire in semi-arid ecosystems

    Science.gov (United States)

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

    2016-04-01

    Keywords: Pilbara, soil CO2 efflux, soil C, soil moisture, soil temperature Introduction Soil respiration (Rs) has become a major research focus given the increase in atmospheric CO2 emissions and the large contribution of these CO2 fluxes from soils (Van Groenigen et al., 2014). In addition to its importance in the global C cycle, Rs is a fundamental indicator of soil health and quality that reflects the level of microbial activity and provides an indication of the ability of soils to support plant growth (Oyonarte et al., 2012; Munoz-Rojas et al., 2015). Wildfires can have a significant impact on Rs rates, with the scale of the impact depending on environmental factors such as temperature and moisture, and organic C content in the soil. Vegetation cover can have a significant effect on regulating organic C contents; and while advances are made into understanding the effects of fire on organic C contents and CO2 fluxes (Granged et al., 2011; Willaarts et al., 2015; Muñoz-Rojas et al., 2016), there is limited knowledge of the variability of Rs across ecosystem types, vegetation communities, and responses to fire. In this research we aimed to assess the impacts of a wildfire on the soil CO2 fluxes and soil respiration in a semi-arid ecosystem of Western Australia (Pilbara biogeographical region), and to understand the main environmental drivers controlling these fluxes in different vegetation types. The study has application for other arid and semi-arid regions of the world. Methods The study area was selected following a wildfire that affected 25 ha in February 2014. Twelve plots were established in the burnt site (B) within a 400 m2 area, and 12 plots in an adjacent unburnt control site. At each site, three plots were installed below the canopy of each of the most representative vegetation types of the areas: Eucalyptus trees, Acacia shrubs and Triodia grasses, and three on bare soil. Soil sampling and measurement of soil CO2 efflux, temperature and moisture were

  12. 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

    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....

  13. Drought impacts on vegetation activity, growth and primary production in humid and arid ecosystems

    OpenAIRE

    Vicente Serrano, Sergio Martín; Gouveia, Célia; Camarero, Jesús Julio; Begueria, Santiago; Trigo, Ricardo; López Moreno, Juan Ignacio; Azorín Molina, César; Pasho, Edmond; Lorenzo-Lacruz, Jorge; Revuelto, Jesús; Morán Tejeda, Enrique; Sánchez Lorenzo, Arturo

    2012-01-01

    Ponencia presentada en: VIII Congreso de la Asociación Española de Climatología celebrado en Salamanca entre el 25 y el 28 de septiembre de 2012. [EN]We have evaluated the response of the Earth biomes to drought using a new global dataset that captures drought effects on vegetation at various time scales. We show that arid and humid biomes are both affected by drought, and that the time scale on which droughts most intensively affects vegetation plays a key role in determining the...

  14. Elevated carbon dioxide alters impacts of precipitation pulses on ecosystem photosynthesis and respiration in a semi-arid grassland.

    Science.gov (United States)

    Bachman, Sarah; Heisler-White, Jana L; Pendall, Elise; Williams, David G; Morgan, Jack A; Newcomb, Joanne

    2010-03-01

    Predicting net C balance under future global change scenarios requires a comprehensive understanding of how ecosystem photosynthesis (gross primary production; GPP) and respiration (Re) respond to elevated atmospheric [CO(2)] and altered water availability. We measured net ecosystem exchange of CO(2) (NEE), GPP and Re under ambient and elevated [CO(2)] in a northern mixed-grass prairie (Wyoming, USA) during dry intervals and in response to simulated precipitation pulse events. Elevated [CO(2)] resulted in higher rates of both GPP and Re across the 2006 growing season, and the balance of these two fluxes (NEE) accounted for cumulative growing season C uptake (-14.4 +/- 8.3 g C m(-2)). Despite lower GPP and Re, experimental plots under ambient [CO(2)] had greater cumulative uptake (-36.2 +/- 8.2 g C m(-2)) than plots under elevated [CO(2)]. Non-irrigated control plots received 50% of average precipitation during the drought of 2006, and had near-zero NEE (1.9 +/- 6.4 g C m(-2)) for the growing season. Elevated [CO(2)] extended the magnitude and duration of pulse-related increases in GPP, resulting in a significant [CO(2)] treatment by pulse day interaction, demonstrating the potential for elevated [CO(2)] to increase the capacity of this ecosystem to respond to late-season precipitation. However, stimulation of Re throughout the growing season under elevated [CO(2)] reduced net C uptake compared to plots under ambient [CO(2)]. These results indicate that although elevated [CO(2)] stimulates gross rates of ecosystem C fluxes, it does not necessarily enhance net C uptake, and that C cycle responses in semi-arid grasslands are likely to be more sensitive to changes in precipitation than atmospheric [CO(2)].

  15. Assessing the role of climate and resource management on groundwater dependent ecosystem changes in arid environments with the Landsat archive

    Science.gov (United States)

    Huntington, Justin; McGwire, Kenneth C.; Morton, Charles; Snyder, Keirith A.; Peterson, Sarah; Erickson, Tyler; Niswonger, Richard G.; Carroll, Rosemary W.H.; Smith, Guy; Allen, Richard

    2016-01-01

    Groundwater dependent ecosystems (GDEs) rely on near-surface groundwater. These systems are receiving more attention with rising air temperature, prolonged drought, and where groundwater pumping captures natural groundwater discharge for anthropogenic use. Phreatophyte shrublands, meadows, and riparian areas are GDEs that provide critical habitat for many sensitive species, especially in arid and semi-arid environments. While GDEs are vital for ecosystem services and function, their long-term (i.e. ~ 30 years) spatial and temporal variability is poorly understood with respect to local and regional scale climate, groundwater, and rangeland management. In this work, we compute time series of NDVI derived from sensors of the Landsat TM, ETM +, and OLI lineage for assessing GDEs in a variety of land and water management contexts. Changes in vegetation vigor based on climate, groundwater availability, and land management in arid landscapes are detectable with Landsat. However, the effective quantification of these ecosystem changes can be undermined if changes in spectral bandwidths between different Landsat sensors introduce biases in derived vegetation indices, and if climate, and land and water management histories are not well understood. The objective of this work is to 1) use the Landsat 8 under-fly dataset to quantify differences in spectral reflectance and NDVI between Landsat 7 ETM + and Landsat 8 OLI for a range of vegetation communities in arid and semiarid regions of the southwestern United States, and 2) demonstrate the value of 30-year historical vegetation index and climate datasets for assessing GDEs. Specific study areas were chosen to represent a range of GDEs and environmental conditions important for three scenarios: baseline monitoring of vegetation and climate, riparian restoration, and groundwater level changes. Google's Earth Engine cloud computing and environmental monitoring platform is used to rapidly access and analyze the Landsat archive

  16. Partitioning understory evapotranspiration in semi-arid ecosystems in Namibia using the isotopic composition of water vapour

    Science.gov (United States)

    de Blécourt, Marleen; Gaj, Marcel; Holtorf, Kim-Kirsten; Gröngröft, Alexander; Brokate, Ralph; Himmelsbach, Thomas; Eschenbach, Annette

    2016-04-01

    In dry environments with a sparse vegetation cover, understory evapotranspiration is a major component of the ecosystem water balance. Consequently, knowledge on the size of evapotranspiration fluxes and the driving factors is important for our understanding of the hydrological cycle. Understory evapotranspiration is made up of soil evaporation and plant transpiration. Soil evaporation can be measured directly from patches free of vegetation. However, when understory vegetation is present distinguishing between soil evaporation and plant transpiration is challenging. In this study, we aim to partition understory evapotranspiration based on an approach that combines the measurements of water-vapour fluxes using the closed chamber method with measurements of the isotopic composition of water vapour. The measurements were done in the framework of SASSCAL (Southern African Science Service Centre for Climate Change and Adaptive Land Management). The study sites were located in three different semi-arid ecosystems in Namibia: thornbush savanna, Baikiaea woodland and shrubland. At each site measurements were done under tree canopies as well as at unshaded areas between the canopies. We measured evaporation from the bare soil and evapotranspiration from patches covered with herbaceous species and shrubs using a transparent chamber connected with an infrared gas analyser (LI-8100A, LICOR Inc.). The stable isotope composition of water vapour inside the chamber and depth profiles of soil water stable isotopes were determined in-situ using a tuneable off-axis integrated cavity output spectroscope (OA-ICOS, Los Gatos Research, DLT 100). Xylem samples were extracted using the cryogenic vacuum extraction method and the isotopic composition of the extracted water was measured subsequently with a cavity-ring-down spectrometer (CRDS L2120-i, Picarro Inc.). We will present the quantified fluxes of understory evapotranspiration measured in the three different ecosystems, show the

  17. Habitat Heterogeneity Variably Influences Habitat Selection by Wild Herbivores in a Semi-Arid Tropical Savanna Ecosystem.

    Directory of Open Access Journals (Sweden)

    Victor K Muposhi

    Full Text Available An understanding of the habitat selection patterns by wild herbivores is critical for adaptive management, particularly towards ecosystem management and wildlife conservation in semi arid savanna ecosystems. We tested the following predictions: (i surface water availability, habitat quality and human presence have a strong influence on the spatial distribution of wild herbivores in the dry season, (ii habitat suitability for large herbivores would be higher compared to medium-sized herbivores in the dry season, and (iii spatial extent of suitable habitats for wild herbivores will be different between years, i.e., 2006 and 2010, in Matetsi Safari Area, Zimbabwe. MaxEnt modeling was done to determine the habitat suitability of large herbivores and medium-sized herbivores. MaxEnt modeling of habitat suitability for large herbivores using the environmental variables was successful for the selected species in 2006 and 2010, except for elephant (Loxodonta africana for the year 2010. Overall, large herbivores probability of occurrence was mostly influenced by distance from rivers. Distance from roads influenced much of the variability in the probability of occurrence of medium-sized herbivores. The overall predicted area for large and medium-sized herbivores was not different. Large herbivores may not necessarily utilize larger habitat patches over medium-sized herbivores due to the habitat homogenizing effect of water provisioning. Effect of surface water availability, proximity to riverine ecosystems and roads on habitat suitability of large and medium-sized herbivores in the dry season was highly variable thus could change from one year to another. We recommend adaptive management initiatives aimed at ensuring dynamic water supply in protected areas through temporal closure and or opening of water points to promote heterogeneity of wildlife habitats.

  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

    Tropical ecosystems undergo changes caused by season, climate or multiple anthropogenic impacts. Such changes may cause gradual or rapid shifts from one state to another. There has been a focus on functional classifications of plants to find tools for monitoring and assessing species status in changing environments. It has been recognised that plant biological characteristics can be related to their response to predominant environmental factors and interactions between other organisms. These findings have resulted in a search for plant functional types (PFTs) that are user-defined groups of species with similar response to environmental resources and disturbance associated to common biological traits. Now, identification of plant functional types is priority area in the climate change research. Satellite Earth observation data is an important tool in providing considerable information on extracting PFT information at global and regional levels. From the modelling perspective, some of the current needs are the refinement of processes that govern community assembly, such as natural and anthropogenic disturbances. PFTs used in large-scale models are insufficient to represent the diversity of responses in natural plant communities. The currently available MODIS PFT map was generated by re-labeling the IGBP land cover type classes. However, the error magnitudes of the MODIS PFT product and their spatial and temporal distributions have not been fully characterized. Remotely sensed derived information of the phenology, community composition and vegetation structure are the key inputs to integrate with the variability in precipitation and temperature to map the spatial distribution of Plant functional types. PFTs allows accurate representation of the land surface by separately specifying the composition and structure of PFTs within a grid cell. Very little research efforts are discernible in India that explicitly address the PFTs. In the present study five natural

  19. Validity of Five Satellite-Based Latent Heat Flux Algorithms for Semi-arid Ecosystems

    Directory of Open Access Journals (Sweden)

    Fei Feng

    2015-12-01

    Full Text Available Accurate estimation of latent heat flux (LE is critical in characterizing semiarid ecosystems. Many LE algorithms have been developed during the past few decades. However, the algorithms have not been directly compared, particularly over global semiarid ecosystems. In this paper, we evaluated the performance of five LE models over semiarid ecosystems such as grassland, shrub, and savanna using the Fluxnet dataset of 68 eddy covariance (EC sites during the period 2000–2009. We also used a modern-era retrospective analysis for research and applications (MERRA dataset, the Normalized Difference Vegetation Index (NDVI and Fractional Photosynthetically Active Radiation (FPAR from the moderate resolution imaging spectroradiometer (MODIS products; the leaf area index (LAI from the global land surface satellite (GLASS products; and the digital elevation model (DEM from shuttle radar topography mission (SRTM30 dataset to generate LE at region scale during the period 2003–2006. The models were the moderate resolution imaging spectroradiometer LE (MOD16 algorithm, revised remote sensing based Penman–Monteith LE algorithm (RRS, the Priestley–Taylor LE algorithm of the Jet Propulsion Laboratory (PT-JPL, the modified satellite-based Priestley–Taylor LE algorithm (MS-PT, and the semi-empirical Penman LE algorithm (UMD. Direct comparison with ground measured LE showed the PT-JPL and MS-PT algorithms had relative high performance over semiarid ecosystems with the coefficient of determination (R2 ranging from 0.6 to 0.8 and root mean squared error (RMSE of approximately 20 W/m2. Empirical parameters in the structure algorithms of MOD16 and RRS, and calibrated coefficients of the UMD algorithm may be the cause of the reduced performance of these LE algorithms with R2 ranging from 0.5 to 0.7 and RMSE ranging from 20 to 35 W/m2 for MOD16, RRS and UMD. Sensitivity analysis showed that radiation and vegetation terms were the dominating variables affecting LE

  20. Spatiotemporal diversity, structure and trophic guilds of insect assemblages in a semi-arid Sabkha ecosystem.

    Science.gov (United States)

    Chenchouni, Haroun; Menasria, Taha; Neffar, Souad; Chafaa, Smail; Bradai, Lyès; Chaibi, Rachid; Mekahlia, Mohamed Nacer; Bendjoudi, Djamel; Si Bachir, Abdelkrim

    2015-01-01

    The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria). The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness) were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA) was applied to determine how vegetation parameters (species richness and cover) influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, of which Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%), saprophages (26.7%), phytophages (20.5%), polyphages (10.8%), coprophages (4.6%); whereas in terms of numbers of species, they can be classified as phytophages (40%), predators (25.3%), polyphages (13.3%), saprophages (12%), coprophages (9.3%). The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different stations of the wetland and seasons.

  1. Spatiotemporal diversity, structure and trophic guilds of insect assemblages in a semi-arid Sabkha ecosystem

    Directory of Open Access Journals (Sweden)

    Haroun Chenchouni

    2015-03-01

    Full Text Available The current study highlights some knowledge on the diversity and structure of insect communities and trophic groups living in Sabkha Djendli (semi-arid area of Northeastern Algeria. The entomofauna was monthly sampled from March to November 2006 using pitfall traps at eight sites located at the vicinity of the Sabkha. Structural and diversity parameters (species richness, Shannon index, evenness were measured for both insect orders and trophic guilds. The canonical correspondence analysis (CCA was applied to determine how vegetation parameters (species richness and cover influence spatial and seasonal fluctuations of insect assemblages. The catches totalled 434 insect individuals classified into 75 species, 62 genera, 31 families and 7 orders, of which Coleoptera and Hymenoptera were the most abundant and constant over seasons and study stations. Spring and autumn presented the highest values of diversity parameters. Individual-based Chao-1 species richness estimator indicated 126 species for the total individuals captured in the Sabkha. Based on catch abundances, the structure of functional trophic groups was predators (37.3%, saprophages (26.7%, phytophages (20.5%, polyphages (10.8%, coprophages (4.6%; whereas in terms of numbers of species, they can be classified as phytophages (40%, predators (25.3%, polyphages (13.3%, saprophages (12%, coprophages (9.3%. The CCA demonstrated that phytophages and saprophages as well as Coleoptera and Orthoptera were positively correlated with the two parameters of vegetation, especially in spring and summer. While the abundance of coprophages was positively correlated with species richness of plants, polyphage density was positively associated with vegetation cover. The insect community showed high taxonomic and functional diversity that is closely related to diversity and vegetation cover in different stations of the wetland and seasons.

  2. Spatial and temporal trends of drought effects in a heterogeneous semi-arid forest ecosystem

    Science.gov (United States)

    Assal, Timothy J.; Anderson, Patrick J.; Sibold, Jason

    2016-01-01

    Drought has long been recognized as a driving mechanism in the forests of western North America and drought-induced mortality has been documented across genera in recent years. Given the frequency of these events are expected to increase in the future, understanding patterns of mortality and plant response to severe drought is important to resource managers. Drought can affect the functional, physiological, structural, and demographic properties of forest ecosystems. Remote sensing studies have documented changes in forest properties due to direct and indirect effects of drought; however, few studies have addressed this at local scales needed to characterize highly heterogeneous ecosystems in the forest-shrubland ecotone. We analyzed a 22-year Landsat time series (1985–2012) to determine changes in forest in an area that experienced a relatively dry decade punctuated by two years of extreme drought. We assessed the relationship between several vegetation indices and field measured characteristics (e.g. plant area index and canopy gap fraction) and applied these indices to trend analysis to uncover the location, direction and timing of change. Finally, we assessed the interaction of climate and topography by forest functional type. The Normalized Difference Moisture Index (NDMI), a measure of canopy water content, had the strongest correlation with short-term field measures of plant area index (R2 = 0.64) and canopy gap fraction (R2 = 0.65). Over the entire time period, 25% of the forested area experienced a significant (p-value drought. The results provide a long-term perspective for the resource management of this area and can be applied to similar ecosystems throughout western North America.

  3. Biological forest ecosystems diversity and there impact in semi arid land, analysis and followed by remote sensing (Alsat-1 data, Steppe of Algeria)

    Science.gov (United States)

    Zegrar, A.

    2008-05-01

    The Algerian forests present an important ecological diversity, due to the different type of weather, from the sub humid to arid. These type of weather have a direct influence on the forests ecosystem and condition the flours composition of these forests as well as their regeneration. The ecological diversity of some forests as part as it's constitution, plays an important role in the natural regeneration, following some natural curses (Forest fire, phenomenon of Chablis, stroke of wood...). The conservation of the biologic diversity and the bets in permanent value of some Forests ecosystem take moreover importance. Because the forest ecosystem have the aspect of uniting the biologic wealth of forests, some interior waters, some agricultural earths and some arid and sub humid earths. In this survey, the utilization of remote sensing data respectively satellite ALSAT-1 and satellite LANDSAT TM in different dates, inform us about impact of arid weather on the ecological diversity in the middle of some vegetal steppe formations and in particular on the regressive evolution of some forests ecosystem under the name of the DEFORESTATION. We have used data of satellite LANDSAT TM of the year 1989 and those of satellite ALSAT-1 of the year 2007, for a multistage study of the regressive evolution of forests ecosystem. an application of the specific treatments especially the classification supervised by the method of maximum of verisimilitude is used in order to identify the most important formations of the zone of survey. The index: NDVI, MSAVI2 and the index of IV verdure is used for characterized and determined the forests formations changes. The arithmetic combinations are used in the system of information geographical IDRISI. And after application of the method of the rations we obtained a picture of the changes. A map of the Vulnerability of the forests ecosystem was realized, this map informs us on the process of deforestation in the natural forests following the

  4. Spatial and Temporal Analysis of Drought Effects in a Heterogeneous Semi-Arid Forest Ecosystem

    Science.gov (United States)

    Assal, T.; Anderson, P. J.; Sibold, J.

    2015-12-01

    Drought-induced forest mortality has been documented across genera in recent years in western North America. Understanding patterns of mortality and plant response to severe drought is important to resource managers, given the frequency of these events are expected to increase in the future. Remote sensing studies have documented changes in forest properties due to direct and indirect effects of drought; however, few have addressed this at local scales needed to characterize highly heterogeneous ecosystems in the forest-shrubland ecotone. We analyzed a 22-year Landsat time series (1985-2012) to determine changes in forest that experienced a relatively dry decade punctuated by two years of extreme drought. We assessed the relationship between vegetation indices and field measures, applied the index to trend analysis to uncover the location, direction and timing of change, and assessed the interaction of climate on topography. The Normalized Difference Moisture Index (NDMI) had the strongest correlation with plant area index (R2 = 0.64) and canopy gap fraction (R2 = 0.65). During the study period, 25% of the forested area experienced a significant (p < 0.05) negative trend in NDMI, compared to less than 10% in a positive trend. Trends were not consistent across forest type as a larger amount of coniferous forest was impacted by negative trends than deciduous forest. Southern aspects were least likely to exhibit a negative trend and north aspects were most prevalent. Field plots with a negative trend had a lower live density, and higher amounts of standing dead and down trees compared to plots with no trend. Our analysis identifies spatially explicit patterns of long-term trends anchored with ground based evidence to highlight areas of forest that are resistant, persistent and vulnerable to severe drought. The results provide a long-term perspective for the resource management of this area and can be applied to similar ecosystems throughout western North America.

  5. Analysis of Molecular Geochemistry of Soil Organic Matter from 17-year Reciprocal Transplant Experiment in Arid Ecosystem: Simulated Climate Pertubation

    Science.gov (United States)

    Hess, N. J.; Tfaily, M.; Bailey, V. L.; McCue, L. A.

    2014-12-01

    Successful development of chemical profiles that link soil carbon vulnerability and resilience to climate change would greatly facilitate assessment of soil ecosystems response to global climate change. Additionally these signatures could be used to support the design of sustainable agricultural and food/energy crop security practices. We test this possibility using soils obtained from a 17-year reciprocal soil transplant experiment between two elevations in the arid environment of eastern Washington [1]. 30-cm diameter soil cores were reciprocally transplanted between the upper and lower sites. Cores were also transplanted in place to control for disturbance. Extracted subcores were incubated in environmental chambers and measured microbial respiration revealed statically a significant decrease in respiratory response as a function of temperature in cores transferred from low elevation to high elevation. We use ultra high resolution mass spectrometry to identify thousands of organic molecules and changes in geochemistry that would indicate the vulnerability of the soil ecosystem to climate perturbation. In our experiments we used methanol extraction followed by direct injection to 12 T ESI FT-ICR MS to identify about 4000 of individual compounds in about 200 mg soils at sub ppm mass accuracy. Chemical formulae were assigned to approximately 65% of the measured peaks using a modified Kujawinski pipeline and second order Kendrick transformations [2] resulted in approximately 75% assigned peaks. Our preliminary analysis finds that while the bulk C content of soils from the cooler, wetter conditions at the upper elevation is approximately twice that of the warmer, drier conditions at lower elevation, the molecular soil geochemistry is remarkably similar. Detailed analysis reveals subtle differences in the lipid, carbohydrate, and condensed hydrocarbon compositional makeup of the soil. Additionally, of the more than 17,000 individual compounds identified approximately

  6. Hydrologic control of the oxygen isotope ratio of ecosystem respiration in a semi-arid woodland

    Directory of Open Access Journals (Sweden)

    J. H. Shim

    2013-07-01

    Full Text Available We conducted high frequency measurements of the δ18O value of atmospheric CO2 from a juniper (Juniperus monosperma woodland in New Mexico, USA, over a four-year period to investigate climatic and physiological regulation of the δ18O value of ecosystem respiration (δR. Rain pulses reset δR with the dominant water source isotope composition, followed by progressive enrichment of δR. Transpiration (ET was significantly related to post-pulse δR enrichment because the leaf water δ18O value showed strong enrichment with increasing vapor pressure deficit that occurs following rain. Post-pulse δR enrichment was correlated with both ET and the ratio of ET to soil evaporation (ET/ES. In contrast, the soil water δ18O value was relatively stable and δR enrichment was not correlated with ES. Model simulations captured the large post-pulse δR enrichments only when the offset between xylem and leaf water δ18O value was modeled explicitly and when a gross flux model for CO2 retro-diffusion was included. Drought impacts δR through the balance between evaporative demand, which enriches δR, and low soil moisture availability, which attenuates δR enrichment through reduced ET. The net result, observed throughout all four years of our study, was a negative correlation of post-precipitation δR enrichment with increasing drought.

  7. Biological soil crust and disturbance controls on surface hydrology in a semi-arid ecosystem

    Science.gov (United States)

    Faist, Akasha M; Herrick, Jeffrey E.; Belnap, Jayne; Van Zee, Justin W; Barger, Nichole N

    2017-01-01

    Biological soil crust communities (biocrusts) play an important role in surface hydrologic processes in dryland ecosystems, and these processes may then be dramatically altered with soil surface disturbance. In this study, we examined biocrust hydrologic responses to disturbance at different developmental stages on sandy soils on the Colorado Plateau. Our results showed that all disturbance (trampling, scalping and trampling+scalping) of the early successional light cyanobacterial biocrusts generally reduced runoff. In contrast, trampling well-developed dark-cyano-lichen biocrusts increased runoff and sediment loss relative to intact controls. Scalping did not increase runoff, implying that soil aggregate structure was important to the infiltration process. Well-developed, intact dark biocrusts generally had lower runoff, low sediment loss, and highest aggregate stability whereas the less-developed light biocrusts were highest in runoff and sediment loss when compared to the controls. These results suggest the importance of maintaining the well-developed dark biocrusts, as they are beneficial for lowering runoff and reducing soil loss and redistribution on the landscape. These data also suggest that upslope patches of light biocrust may either support water transport to downslope vegetation patches or alternatively this runoff may place dark biocrust patches at risk of disruption and loss, given that light patches increase runoff and thus soil erosion potential.

  8. Both biocrust cover and soil warming increased inorganic and organic P fractions in a semi-arid ecosystem of Central Spain

    Science.gov (United States)

    García-Velázquez, Laura; Gallardo, Antonio; Maestre, Fernando T.

    2017-04-01

    Semi-arid and arid ecosystem represents 41% of Earth's surface, and climate change is expected to increase this percentage of drylands. The increase in aridity has a profound effect on biogeochemical cycles, inducing an imbalance in the soil nitrogen (N): phosphorus (P) ratio, with subsequent impacts on ecosystem services. In addition, primary productivity in terrestrial ecosystems can be destabilized by the increase of atmospheric N deposition, and P may become the most limiting nutrient in these altered ecosystems. Some studies have shown that aridity and climate change influence N cycling in drylands, however the resilience of labile and recalcitrant, inorganic and organic fractions of P in semi-arid ecosystems is still unknown. Our main hypothesis stipulates that soil warming might induce an increase of the inorganic P fractions versus the organic ones because of a rise of biological activity in drylands, but these variations may be modulated by the presence of Biological Soil Crust (BSC) and counteracted by the predicted precipitation decrease. We tested how warming (ambient vs. ˜2.5 ˚ C increase), rainfall exclusion (ambient vs. ˜30% reduction in total annual rainfall) and biocrust cover (incipient vs. well-developed biocrusts) alter organic and inorganic P fractions (resin-P, NaHCO3-P, NaOH-P, HCl-P and residual P) in a 5-yr field experiment. We performed a combination of classic methods of soil P fractionation to determine proportions of organic and inorganic P, representing different indexes related to availability and recalcitrance of P. The presence of BSC had a great influence through an increase in all P fractions. Soil warming increased inorganic P (NaHCO3-P, NaOH-P and HCl-P) but also organic P fractions (NaHCO3-P and NaOH-P) f. In addition, we detected an increase in the recalcitrance-to-labil P ratio over time possibly due to microbial immobilization. The rainfall exclusion experiment had no effect on any P fractions. Our results suggest that

  9. Vegetation-induced soil water repellency as a strategy in arid ecosystems. A geochemical approach in Banksia woodlands (SW Australia)

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; González-Pérez, Jose Antonio; Zavala, Lorena M.; Stevens, Jason; Jordan, Antonio

    2016-04-01

    Introduction Banksia woodlands (BW) are iconic ecosystems of Western Australia (WA) composed by an overstorey dominated by Proteaceae, e.g. Banksia menziesii and Banksia attenuata, in combination with other species, such as Eucalyptus spp., Verticordia spp. or Melaleuca spp. Although located in very poor dune soils, BW provide numerous ecosystem services and sustain a high biodiversity. In this area, annual rainfall is relatively high (about 800 mm) but permeability of the sandy substrate leads to a functionally arid ecosystem. Currently, BW are threatened by sand mining activities and urban expansion; therefore conservation and restoration of these woodlands are critical. Despite numerous efforts, the success of restoration plans is usually poor mostly due to the high sensitivity to drought stress and poor seedling survival rates (5-30%) (Benigno et al., 2014). A characteristic feature of BW is their root architecture, formed by a proteoid (cluster) system that spreads to form thick mats below the soil surface, favouring the uptake of nutrients (especially, P), and preventing soil erosion. Root exudates are related to numerous plant functions, as they facilitate penetration of roots in soil and enhance the extraction of scarce mineral nutrients and its further assimilation. Exudates may also interact directly with soil or indirectly through microbial mediated events being also related to soil water repellency (SWR; Lozano et al, 2014). Knowledge about the specific compounds able to induce SWR is limited (Doerr et al., 2000), but it is generally accepted that is caused by organic molecules coating the surface of soil mineral particles and aggregates (Jordán et al., 2013). Proteaceae release short-chained organic acids to enhance phosphate acquisition, which have been also reported to be related with SWR (Jiménez-Morillo et al., 2014). It is hypothesized that disruption of water dynamics in mature BW soils is underlying the failure of restoration plans. This

  10. Hyperspectral remote sensing tools for quantifying plant litter and invasive species in arid ecosystems

    Science.gov (United States)

    Nagler, Pamela L.; Sridhar, B.B. Maruthi; Olsson, Aaryn Dyami; Glenn, Edward P.; van Leeuwen, Willem J.D.; Thenkabail, Prasad S.; Huete, Alfredo; Lyon, John G.

    2012-01-01

    Green vegetation can be distinguished using visible and infrared multi-band and hyperspectral remote sensing methods. The problem has been in identifying and distinguishing the non-photosynthetically active radiation (PAR) landscape components, such as litter and soils, and from green vegetation. Additionally, distinguishing different species of green vegetation is challenging using the relatively few bands available on most satellite sensors. This chapter focuses on hyperspectral remote sensing characteristics that aim to distinguish between green vegetation, soil, and litter (or senescent vegetation). Quantifying litter by remote sensing methods is important in constructing carbon budgets of natural and agricultural ecosystems. Distinguishing between plant types is important in tracking the spread of invasive species. Green leaves of different species usually have similar spectra, making it difficult to distinguish between species. However, in this chapter we show that phenological differences between species can be used to detect some invasive species by their distinct patterns of greening and dormancy over an annual cycle based on hyperspectral data. Both applications require methods to quantify the non-green cellulosic fractions of plant tissues by remote sensing even in the presence of soil and green plant cover. We explore these methods and offer three case studies. The first concerns distinguishing surface litter from soil using the Cellulose Absorption Index (CAI), as applied to no-till farming practices where plant litter is left on the soil after harvest. The second involves using different band combinations to distinguish invasive saltcedar from agricultural and native riparian plants on the Lower Colorado River. The third illustrates the use of the CAI and NDVI in time-series analyses to distinguish between invasive buffelgrass and native plants in a desert environment in Arizona. Together the results show how hyperspectral imagery can be applied to

  11. Using local biodiversity to prevent pollution transfers to environmental components of a Mediterranean semi-arid ecosystem

    Science.gov (United States)

    Heckenroth, Alma; Rabier, Jacques; Laffont-Schwob, Isabelle

    2014-05-01

    In arid and semi-arid Mediterranean coastal areas, metals and metalloids (MM) pollution coming from unreclaimed brownfields has increased the negative environmental stresses leading to ecosystems degradations as soil erosion and losses of organic matter and biodiversity. On these sites, maintaining or restoring a local vegetation cover is considered as a key step to stop the degradation cycle. Furthermore, in a context of high pollution occurring in natural areas, phytoremediation is considered as an attractive alternative to conventional soil remediation techniques, the first reducing pollution transfers, improving the soil quality. In protected or natural areas, it is also important to perceive then design phytoremediation as a way to assist ecosystems recovery, using the restoration ecology concepts. However, only few works in the literature deal with the potential use of native Mediterranean plant species for phytoremediation. On the South-East coast of Marseille (France), the activity of the former smelting factory of l'Escalette, ceased since 1925. However, its brownfield is still a source of pollution by trace metals and metalloids for abiotic and biotic components of the surrounding massif. This massif hosts a rich biodiversity with rare and protected plant species despite the metallic pollution and this area has been included in the recently created first peri-urban French National Park of Calanques. In this context, an integrated research project is being conducted with local actors and stakeholders, from the selection of native plant species, assessment and optimization of phytostabilization capacities of selected species, to the development of ecological engineering techniques well adapted to local constraints and phytostabilization field trials. The first part of this study has been conducted on two areas, corresponding to different pollution pattern, plant communities and environmental drivers: a halophytic area, characterized by typical coastal

  12. Impact of climate change on acid mine drainage generation and contaminant transport in water ecosystems of semi-arid and arid mining areas

    Science.gov (United States)

    Anawar, Hossain Md.

    Disposal of untreated and treated mining wastes and tailings exerts a significant threat and hazard for environmental contamination including groundwater, surface water, wetlands, land, food chain and animals. In order to facilitate remediation techniques, it is important to understand the oxidation of sulfidic minerals, and the hydrolysis of the oxidation products that result in production of acid mine drainage (AMD), toxic metals, low pH, SO42- and Fe. This review has summarized the impacts of climate change on geochemical reactions, AMD generation, and water quality in semi-arid/arid mining environments. Besides this, the study included the effects of hydrological, seasonal and climate change on composition of AMD, contaminant transport in watersheds and restoration of mining sites. Different models have different types of limitations and benefits that control their adaptability and suitability of application in various mining environments. This review has made a comparative discussion of a few most potential and widely used reactive transport models that can be applied to simulate the effect of climate change on sulfide oxidation and AMD production from mining waste, and contaminant transport in surface and groundwater systems.

  13. 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...

  14. The effects of clouds and aerosols on net ecosystem CO2 exchange over semi-arid Loess Plateau of Northwest China

    Directory of Open Access Journals (Sweden)

    T. Wang

    2010-09-01

    Full Text Available The impacts of clouds and atmospheric aerosols on the terrestrial carbon cycle at semi-arid Loess Plateau in Northwest China are investigated, by using the observation data obtained at the SACOL (Semi-Arid Climate and Environment Observatory of Lanzhou University site. Daytime (solar elevation angles of larger than 50° net ecosystem exchange (NEE of CO2 obtained during the midgrowing season (July–August are analyzed with respect to variations in the diffuse radiation, cloud cover and aerosol optical depth (AOD. Results show a significant impact by clouds on the CO2 uptake by the grassland (with smaller LAI values located in a semi-arid region, quite different from areas covered by forests and crops. The light saturation levels in the canopy are low, with a value of about 434.8 W m−2. Thus, under overcast conditions of optically thick clouds, the CO2 uptake increases with increasing clearness index (the ratio of global solar radiation received at the Earth surface to the extraterrestrial irradiance at a plane parallel to the Earth surface, and a maximum CO2 uptake and light use efficiency of vegetation occur with the clearness index of about 0.37 and lower air temperature. Under other sky conditions, CO2 uptake decreases with cloudiness but light use efficiency is enhanced, due to increased diffuse fraction of PAR. Additionally, under cloudy conditions, changes in the NEE of CO2 also result from the interactions of many environmental factors, especially the air temperature. In contrast to its response to changes in solar radiation, the carbon uptake shows a slightly negative response to increased AOD. The reason for the difference in the response of the semi-arid grassland from that of the forest and crop lands may be due to the difference in the canopy's architectural structure.

  15. The possibilities and pitfalls presented by a pragmatic approach to ecosystem service valuation in an arid biodiversity hotspot

    CSIR Research Space (South Africa)

    O'Farrell, PJ

    2011-01-01

    Full Text Available in the arid Succulent Karoo biome in western South Africa - a globally recognised biodiversity hotspot. They were looking for ways and values that could be used to promote conservation in this region through the adoption of sustainable land-use practices which...

  16. Effects of feral free-roaming horses on semi-arid rangeland ecosystems: an example from the sagebrush steppe

    Science.gov (United States)

    Feral horses (Equus caballus) are viewed as a symbol of freedom and power; however, they are also a largely unmanaged, non-native grazer in North America, South America, and Australia. Information on their influence on vegetation and soil characteristics in semi-arid rangelands has been limited by ...

  17. An evaluation of object-oriented image analysis techniques to identify motorized vehicle effects in semi-arid to arid ecosystems of the American West

    Science.gov (United States)

    Mladinich, C.

    2010-01-01

    Human disturbance is a leading ecosystem stressor. Human-induced modifications include transportation networks, areal disturbances due to resource extraction, and recreation activities. High-resolution imagery and object-oriented classification rather than pixel-based techniques have successfully identified roads, buildings, and other anthropogenic features. Three commercial, automated feature-extraction software packages (Visual Learning Systems' Feature Analyst, ENVI Feature Extraction, and Definiens Developer) were evaluated by comparing their ability to effectively detect the disturbed surface patterns from motorized vehicle traffic. Each package achieved overall accuracies in the 70% range, demonstrating the potential to map the surface patterns. The Definiens classification was more consistent and statistically valid. Copyright ?? 2010 by Bellwether Publishing, Ltd. All rights reserved.

  18. The net effect of abiotic conditions and biotic interactions in a semi-arid ecosystem NE Spain: implications for the management and restoration.

    Science.gov (United States)

    Pueyo, Yolanda; Arroyo, Antonio I.; Saiz, Hugo; Alados, Concepción L.

    2014-05-01

    Degradation in arid and semiarid lands can be irreversible without human intervention, due to a positive plant-soil feedback where the loss of vegetation cover leads to soil degradation, which in turn hampers plant establishment. Human intervention in restoration actions usually involves the amendment of the degraded abiotic conditions, revegetation of bare areas, or both. However, abiotic amelioration is often expensive and too intrusive, and revegetation is not successful in many cases. Biotic interactions between plants, and more specifically facilitation by a "nurse" plant, have been proposed as a new via to take profit of improved abiotic conditions without intervention, and to increase the success rate of revegetation actions. But "nurse" plants can also interfere with others (i.e. by competition for resources or the release of allelopathic compounds), and the net balance between facilitation and interference could depend on plant types involved. We present recent observational and experimental studies performed in the semiarid ecosystems of the Middle Ebro Valley (NE Spain) about the role of abiotic conditions and biotic interactions in the productivity, dynamics and diversity of plant communities under different stress conditions (aridity and grazing). We found that all plant types studied (shrubs and perennial grasses) improved abiotic conditions (soil temperature and water availability for plants) with respect to open areas. However, only some shrubs (mainly Salsola vermiculata) had a positive net balance in the biotic interactions between plants, while other shrubs (Artemisia herba-alba) and perennial grasses (Lygeum spartum) showed interference with other plants. Moreover, the net balance between facilitation and interference among plants in the community shifted from competitive to neutral or from neutral to facilitative with increasing aridity. Grazing status did not strongly change the net biotic interactions between plants. Our results suggest that

  19. Planning aquatic ecosystem restoration monitoring programs

    Energy Technology Data Exchange (ETDEWEB)

    Thom, R.M.; Wellman, K.F.

    1997-01-01

    This study was conducted as part of the Evaluation of Environmental Investments Research Program (EEIRP). The EEIRP is sponsored by the US Army Corps of Engineers. The objectives of this work are to (1) identify relevant approaches and features for environmental investment measures to be applied throughout the project life; (2) develop methods to access the effectiveness of the approach or feature for providing the intended environmental output; (3) develop and provide guidance for formulating environmental projects; and (4) provide guidance for formulating and identifying relevant cost components of alternate restoration plans.

  20. Inter-annual Variability of Evapotranspiration in a Semi-arid Oak-savanna Ecosystem: Measured and Modeled Buffering to Precipitation Changes

    Science.gov (United States)

    Raz-Yaseef, N.; Sonnentag, O.; Kobayashi, H.; Baldocchi, D. D.

    2010-12-01

    Precipitation (P) is the primary control on vegetation dynamics and productivity, implying that climate induced disturbances in frequency and timing of P are intimately coupled with fluxes of carbon, water and energy. Future climate change is expected to increase extreme rainfall events as well as droughts, suggesting linked vegetation changes to an unknown extent. Semi-arid climates experience large inter-annual variability (IAV) in P, creating natural conditions adequate to study how year-to-year changes in P affect atmosphere-biosphere fluxes. We used a 10-year flux database collected at a semi-arid savanna site in order to: (1) define IAV in P by means of frequency and timing; (2) investigate how changes in P affect the ecohydrology of the forest and its partitioning into the main vapor fluxes, and (3) evaluate model capability to predict IAV of carbon and water fluxes above and below the canopy. This is based on the perception that the capability of process-oriented models to construct the deviation, and not the average, is important in order to correctly predict ecosystem sensitivity to climate change. Our research site was a low density and low LAI (0.8) semi-arid (P=523±180 mm yr-1) savanna site, combined of oaks and grass, and located at Tonzi ranch, California. Measurements of carbon and water fluxes above and below the tree canopy using eddy covariance and supplementary measurements have been made since 2001. Measured fluxes were compared to modeled based on two bio-meteorological process-oriented ecosystem models: BEPS and 3D-CAONAK. Our results show that IAV in P was large, and standard deviation (STD) was 38% of the average. Accordingly, the wet soil period (measured volumetric water content > 8%) varied between 156 days in dry years to 301 days in wet years. IAV of the vapor fluxes were lower than that of P (STD was 17% for the trees and 23% for the floor components), suggesting on ecosystem buffering to changes in P. The timing of grass green up

  1. Toxicity Bioassays for Ecological Risk Assessment in Arid and Semiarid Ecosystems. Reviews Environmental Contamination and Toxicology 168:43-98.

    Energy Technology Data Exchange (ETDEWEB)

    Markwiese, J.T.; Ryti, R.T.; Hooten, M.M.; Michael, D.I.; Hlohowskyj, I.

    2001-02-01

    This paper discusses current limitations for performing ecological risk assessments in dry environments (i.e., ecosystems that are characteristic of many DOE Facilities) and presents novel approaches to addressing ecological risk in such systems.

  2. Assessing the role of climate and resource management on groundwater dependent ecosystem changes in arid environments with the landsat archive

    Science.gov (United States)

    Groundwater dependent ecosystems (GDEs) rely on the presence of subsurface or surficial expressions of groundwater. These systems are receiving more attention as temperature increases, droughts are more extreme, and where groundwater development captures natural discharge for anthropogenic use. Phre...

  3. Effect of biological soil crusts on seed germination and growth of an exotic and two native plant species in an arid ecosystem.

    Science.gov (United States)

    Song, Guang; Li, Xinrong; Hui, Rong

    2017-01-01

    Biological soil crusts (BSCs) can improve the stability and health of native plant communities in arid ecosystems. However, it is unknown whether BSCs can also inhibit invasions of exotic vascular plants on stabilized reclaimed sand dunes. To answer this question, we conducted a greenhouse experiment to test the effects of cyanobacteria-dominated BSCs on 1) seed germination and biomass of an exotic grass (Stipa glareosa P. Smirn.), and 2) individual biomass of the exotic S. glareosa growing with two native plants, Eragrostis poaeoides Beauv. and Artemisia capillaris Thunb. Our experiment included three BSC treatments (intact crust, disturbed crust, and bare soil) and five species trials (native E. poaeoides alone, E. poaeoides mixed with exotic S. glareosa, native A. capillaris alone, A. capillaris mixed with exotic S. glareosa, and S. glareosa alone). The results showed that cyanobacteria-dominated crusts can significantly reduce the cumulative percent germination of the exotic grass (Pstabilized sand dunes may reduce the germination of the exotic and two native plants. The effect of reducing exotic and native plant seeds germination would maintain more diverse plant communities and contribute to the formation of clumped vegetation patterns. We conclude that BSCs act as a natural regulator for vegetation patterns and thus promote ecosystem stability and sustainability.

  4. GLOBEC (Global Ocean Ecosystems Dynamics: Northwest Atlantic program

    Science.gov (United States)

    1991-01-01

    The specific objective of the meeting was to plan an experiment in the Northwestern Atlantic to study the marine ecosystem and its role, together with that of climate and physical dynamics, in determining fisheries recruitment. The underlying focus of the GLOBEC initiative is to understand the marine ecosystem as it related to marine living resources and to understand how fluctuation in these resources are driven by climate change and exploitation. In this sense the goal is a solid scientific program to provide basic information concerning major fisheries stocks and the environment that sustains them. The plan is to attempt to reach this understanding through a multidisciplinary program that brings to bear new techniques as disparate as numerical fluid dynamic models of ocean circulation, molecular biology and modern acoustic imaging. The effort will also make use of the massive historical data sets on fisheries and the state of the climate in a coordinated manner.

  5. Environmental effects are stronger than human effects on mammalian predator-prey relationships in arid Australian ecosystems.

    Science.gov (United States)

    Allen, Benjamin L; Fawcett, Alana; Anker, Alison; Engeman, Richard M; Lisle, Allan; Leung, Luke K-P

    2018-01-01

    Climate (drought, rainfall), geology (habitat availability), land use change (provision of artificial waterpoints, introduction of livestock), invasive species (competition, predation), and direct human intervention (lethal control of top-predators) have each been identified as processes driving the sustainability of threatened fauna populations. We used a systematic combination of empirical observational studies and experimental manipulations to comprehensively evaluate the effects of these process on a model endangered rodent, dusky hopping-mice (Notomys fuscus). We established a large manipulative experiment in arid Australia, and collected information from relative abundance indices, camera traps, GPS-collared dingoes (Canis familiaris) and dingo scats, along with a range of related environmental data (e.g. rainfall, habitat type, distance to artificial water etc.). We show that hopping-mice populations were most strongly influenced by geological and climatic effects of resource availability and rainfall, and not land use, invasive species, or human effects of livestock grazing, waterpoint provision, or the lethal control of dingoes. Hopping-mice distribution declined along a geological gradient of more to less available hopping-mice habitat (sand dunes), and their abundance was driven by rainfall. Hopping-mice populations fluctuated independent of livestock presence, artificial waterpoint availability or repeated lethal dingo control. Hopping-mice populations appear to be limited first by habitat availability, then by food availability, then by predation. Contemporary top-predator control practices (for protection of livestock) have little influence on hopping-mice behaviour or population dynamics. Given our inability to constrain the effects of predation across broad scales, management actions focusing on increasing available food and habitat (e.g. alteration of fire and herbivory) may have a greater chance of improving the conservation status of hopping

  6. The active microbial diversity drives ecosystem multifunctionality and is physiologically related to carbon availability in Mediterranean semi-arid soils

    Czech Academy of Sciences Publication Activity Database

    Bastida, F.; Torres, I.F.; Moreno, J.L.; Baldrian, Petr; Ondono, S.; Ruiz-Navarro, A.; Hernández, T.; Richnow, H. H.; Starke, R.; Garcia, C.; Jehmlich, N.

    2016-01-01

    Roč. 25, č. 18 (2016), s. 4660-4673 ISSN 0962-1083 R&D Projects: GA MŠk(CZ) LM2015055 Institutional support: RVO:61388971 Keywords : bacteria * community ecology * ecosystem services Subject RIV: EE - Microbiology, Virology Impact factor: 6.086, year: 2016

  7. Enhanced precipitation-variability effects on water losses and ecosystem functioning: Differential response of arid and mesic regions

    Science.gov (United States)

    Climate change will result in increased precipitation variability with more extreme events across a range of temporal scales. We used a process-based ecosystem model to simulate water losses and soil water availability to plants at 35 grassland locations in the central U.S. under four level of prec...

  8. Ecohydrology across Scales in an Arid, Human-dominated Landscape: Implications for Ecosystems, Water Availability and Human Interactions

    Science.gov (United States)

    Belnap, J.; Deems, J. S.; Kind, A.; Munson, S.; Neff, J.; Okin, G.; Painter, T. H.; Reheis, M. C.; Reynolds, R. L.; Wilcox, B. P.

    2011-12-01

    Arid and semi-arid regions constitute over 35% of global lands. The utilization of these areas is increasing rapidly in response to rising human populations and attendant food needs. In addition, they are also foci for activities associated with energy production, mineral extraction, military training and conflict, and recreation. The resultant disturbance reduces the protective cover of plants and physical and biological soil crusts. This leads to accelerated soil loss by both wind and water, across a wide range of parent materials, textures, or soil surface ages. Further vulnerability to soil erosion is expected with predicted future drier and hotter climates, as plant cover declines and fires increase. Synergistic effects, such as surface disturbance occurring during drought periods in plant communities dominated by annual weeds, can exacerbate the situation further. At a local scale, the redistribution of soil by wind and water results in nutrients being more heterogeneously distributed, subsequently altering abundance and distribution of plants, animals, and rates of biogeochemical cycling. Particles transported by wind from disturbed settings can be deposited in washes, subsequently entering streams and rivers.Particles saltating across the soil surface are also frequently deposited in washes, subsequently entering streams and rivers. This process represents a local loss of soil fertility and a local and regional decrease in water quality, as sediment and salts enter water bodies. At the larger watershed scale, dust is deposited on nearby snow cover, darkening the snow and increasing melt rates. Increased melt rates decrease the length of the snow-cover season, increasing water losses to evapotranspiration and thus the amount of water entering streams and rivers. As water quantity decreases, salts and sediments are concentrated, thereby further decreasing water quality. As water becomes scarcer in drylands around the world, the diminishing integrity of the

  9. Ecosystem properties of semi-arid savanna grassland in West Africa and its relationship to environmental variability

    DEFF Research Database (Denmark)

    Tagesson, Torbern; Fensholt, Rasmus; Guiro, Idrissa

    2015-01-01

    he Dahra field site in Senegal, West Africa, was established in 2002 to monitor ecosystem properties of semiarid savanna grassland and their responses to climatic and environmental change. This article describes the environment and the ecosystem properties of the site using a unique set of in situ......), biomass, vegetation water content, and land-atmosphere exchanges of carbon (NEE) and energy. The Dahra field site experiences a typical Sahelian climate and is covered by coexisting trees (~3% canopy cover) and grass species, characterizing large parts of the Sahel. This makes the site suitable...... of remotely sensed spectral vegetation indices covering different wavelength regions. The presented time series of in situ data have great potential for dryland dynamics studies, global climate change related research and evaluation and parameterization of remote sensing products and dynamic vegetation models....

  10. Vegetation cover change detection and assessment in arid environment using multi-temporal remote sensing images and ecosystem management approach

    Science.gov (United States)

    Abdelrahman Aly, Anwar; Mosa Al-Omran, Abdulrasoul; Shahwan Sallam, Abdulazeam; Al-Wabel, Mohammad Ibrahim; Shayaa Al-Shayaa, Mohammad

    2016-04-01

    Vegetation cover (VC) change detection is essential for a better understanding of the interactions and interrelationships between humans and their ecosystem. Remote sensing (RS) technology is one of the most beneficial tools to study spatial and temporal changes of VC. A case study has been conducted in the agro-ecosystem (AE) of Al-Kharj, in the center of Saudi Arabia. Characteristics and dynamics of total VC changes during a period of 26 years (1987-2013) were investigated. A multi-temporal set of images was processed using Landsat images from Landsat4 TM 1987, Landsat7 ETM+2000, and Landsat8 to investigate the drivers responsible for the total VC pattern and changes, which are linked to both natural and social processes. The analyses of the three satellite images concluded that the surface area of the total VC increased by 107.4 % between 1987 and 2000 and decreased by 27.5 % between years 2000 and 2013. The field study, review of secondary data, and community problem diagnosis using the participatory rural appraisal (PRA) method suggested that the drivers for this change are the deterioration and salinization of both soil and water resources. Ground truth data indicated that the deteriorated soils in the eastern part of the Al-Kharj AE are frequently subjected to sand dune encroachment, while the southwestern part is frequently subjected to soil and groundwater salinization. The groundwater in the western part of the ecosystem is highly saline, with a salinity ≥ 6 dS m-1. The ecosystem management approach applied in this study can be used to alike AE worldwide.

  11. Synthesis report: program ecosystems, transport, pollutions, 1998 - 2001; Rapport de synthese: programme ecosystemes, transport, pollutions, 1998 - 2001

    Energy Technology Data Exchange (ETDEWEB)

    Etchelecou, A.; Deletraz, G.; Elichegaray, Ch

    2001-04-01

    The ''Ecosystems, Transports, Pollution Program'' ETP Program, has been elaborated to evaluate the road pollution impacts on the mountain ecosystems. Four mountains valleys have been chosen: two in Alps (Chamonix and Maurienne) and two in Pyrenees (Biriatou and Vallee d'Aspe). This Program presents six objectives: the road traffic characterization, the pollutants emission estimation, the pollutants concentrations in the air, the pollutants dispersion according to relief, the relationships between pollutants emissions and bio-monitoring, the road pollution effects on nearby ecosystems. (A.L.B.)

  12. Comment on: Shukla, M.K. et al., 2006: Physical and chemical properties of soils under some pinon-juniper-oak canopies in a semi-arid ecosystem in New Mexico

    DEFF Research Database (Denmark)

    Mollerup, Mikkel; Jensen, Jens Raunsø

    2008-01-01

    The paper by Shukla et al. [2006. Physical and chemical properties of soils under some pinon-juniper-oak canopies in an semi-arid ecosystem in New Mexico. Journal of Arid Environment 66, 673-685] treats interesting topics of sustainability of different ecosystems and their water availability....... However, the physical-based infiltration theories by Green and Ampt [1911. Studies on soil physics, I, flow of air and water through soils. Journal of Agricultural Science 4, 1-24] and Philip [1957. The theory of infiltration: 1. The infiltration equation and its solution. Soil Science 83, 345-357] seems...... to be applied without necessary reflections. The actual analysis can have resulted in coefficients without their original physical significance...

  13. EnviroAtlas - Ecosystem Services Market-Based Programs Web Service, U.S., 2016, Forest Trends' Ecosystem Marketplace

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas web service contains layers depicting market-based programs and projects addressing ecosystem services protection in the United States. Layers...

  14. Soil and vegetation-atmosphere exchange of NO, NH3, and N2O from field measurements in a semi arid grazed ecosystem in Senegal

    DEFF Research Database (Denmark)

    Delon, C.; Galy-Lacaux, C.; Serça, D.

    2017-01-01

    compounds emissions in November 2013, whereas emissions in July 2012 and 2013, when the herbaceous strata was sparse, were dominated by microbial processes in the soil. CO2 respiration fluxes were high in the beginning (107 ± 26 mg m−2 h−1 in July 2013) and low in the end of the wet season (32 ± 5 mg m−2 h......The alternating between dry and wet seasons and the consecutive microbial responses to soil water content in semiarid ecosystems has significant consequences on nitrogen exchanges with the atmosphere. Three field campaigns were carried out in a semi arid sahelian rangeland in Dahra (Ferlo, Senegal......), two at the beginning of the wet season in July 2012 and July 2013, and the third one in November 2013 at the end of the wet season. The ammonia emission potentials of the soil ranged from 271 to 6628, indicating the soil capacity to emit NH3. The ammonia compensation point in the soil ranged between 7...

  15. Multi-satellite sensor study on precipitation-induced emission pulses of NOx from soils in semi-arid ecosystems

    Directory of Open Access Journals (Sweden)

    J. Zörner

    2016-07-01

    Full Text Available We present a top-down approach to infer and quantify rain-induced emission pulses of NOx ( ≡  NO + NO2, stemming from biotic emissions of NO from soils, from satellite-borne measurements of NO2. This is achieved by synchronizing time series at single grid pixels according to the first day of rain after a dry spell of prescribed duration. The full track of the temporal evolution several weeks before and after a rain pulse is retained with daily resolution. These are needed for a sophisticated background correction, which accounts for seasonal variations in the time series and allows for improved quantification of rain-induced soil emissions. The method is applied globally and provides constraints on pulsed soil emissions of NOx in regions where the NOx budget is seasonally dominated by soil emissions. We find strong peaks of enhanced NO2 vertical column densities (VCDs induced by the first intense precipitation after prolonged droughts in many semi-arid regions of the world, in particular in the Sahel. Detailed investigations show that the rain-induced NO2 pulse detected by the OMI (Ozone Monitoring Instrument, GOME-2 and SCIAMACHY satellite instruments could not be explained by other sources, such as biomass burning or lightning, or by retrieval artefacts (e.g. due to clouds. For the Sahel region, absolute enhancements of the NO2 VCDs on the first day of rain based on OMI measurements 2007–2010 are on average 4 × 1014  molec cm−2 and exceed 1 × 1015  molec cm−2 for individual grid cells. Assuming a NOx lifetime of 4 h, this corresponds to soil NOx emissions in the range of 6 up to 65 ng N m−2 s−1, which is in good agreement with literature values. Apart from the clear first-day peak, NO2 VCDs are moderately enhanced (2 × 1014  molec cm−2 compared to the background over the following 2 weeks, suggesting potential further emissions during that period of about 3.3 ng N m−2

  16. Inferring Resilience to Fragmentation-Induced Changes in Plant Communities in a Semi-Arid Mediterranean Ecosystem

    Science.gov (United States)

    de Frutos, Ángel; Navarro, Teresa; Pueyo, Yolanda; Alados, Concepción L.

    2015-01-01

    Predicting the capacity of ecosystems to absorb impacts from disturbance events (resilience), including land-use intensification and landscape fragmentation, is challenging in the face of global change. Little is known about the impacts of fragmentation on ecosystem functioning from a multi-dimensional perspective (multiple traits). This study used 58 500-m linear transects to quantify changes in the functional composition and resilience of vascular plant communities in response to an increase in landscape fragmentation in 18 natural scrubland fragments embedded within a matrix of abandoned crop fields in Cabo de Gata-Níjar Natural Park, Almería, Spain. Changes in functional community composition were measured using functional diversity indices (functional richness and functional dispersion) that were based on 12 plant traits. Resilience was evaluated using the functional redundancy and response diversity from the perspective of plant dispersal, which is important, particularly, in fragmented landscapes. Scrubland fragmentation was measured using the Integral Index of Connectivity (IIC). The functional richness of the plant communities was higher in the most fragmented scrubland. Conversely, the functional dispersion (i.e., spread) of trait values among species in the functional trait space was lower at the most fragmented sites; consequently, the ecological tolerance of the vegetation to scrubland fragmentation decreased. Classifying the plant species into four functional groups indicated that fragmentation favoured an increase in functional redundancy in the ‘short basal annual forbs and perennial forbs’ group, most of which are species adapted to degraded soils. An assessment based on the traits associated with plant dispersal indicated that the resilience of ‘woody plants’, an important component in the Mediterranean scrubland, and habitat fragmentation were negatively correlated; however, the correlation was positive in the ‘short basal annual

  17. [Coupling relationship between water and salt of waters ecosystems in arid zone: a case study in Xinjiang Tarim River basin].

    Science.gov (United States)

    Wang, Ranghui; Fan, Zili; Ma, Yingjie

    2002-02-01

    The pollution of waters ecosystems is caused by natural and artificial factors in Tarim River. Temporal and spatial variation of surface runoff is the main reason for changes of coupling relationship between water and salt. In the end of 1950s, mineralization degree was less than 1.0 g.L-1 from the upper reaches to the lower reaches of Tetema Lake in Tarim River. At present, only in July, August and October, mineralization degree is less than 1.0 g.L-1. During the other months, mineralization degree is more than 3.0 g.L-1 in Alaer Lake. In Qiala (the lower reaches of Tarim River), mineralization degree is more than 1.0 g.L-1 except in March. Moreover, mineralization degree is about 5.0 g.L-1 in July and December. It is showed that annual water quality belongs to the fifth seriously polluted water in Alaer, Xinquman and Yingbazha. Meanwhile, annual water quality in Qiala belongs to the fourth polluted water. In a word, water quality state and hydrological chemistry component are the most obviously indicator for coupling relationship between water and salt in Tarim River.

  18. The effectiveness of surface liming in ameliorating the phytotoxic effects of soil contaminated by copper acid leach pad solution in an arid ecosystem

    Science.gov (United States)

    Golos, Peter

    2016-04-01

    Revegetation of sites following soil contamination can be challenging especially in identifying the most effective method for ameliorating phytotoxic effects in arid ecosystems. This study at a copper mine in the Great Sandy Desert of Western Australia investigated vegetation restoration of a site contaminated by acid (H2SO4) leach pad solution. Elevated soil copper at low soil pH is phytotoxic to plant roots inhibiting root elongation. In arid ecosystems where rapid root growth is crucial for seedling survival post germination physical or chemical barriers to root growth need to be identified and ameliorated. Initial attempt at rehabilitation of contaminated site with hydrated lime (CaOH2) at 2 tonnes/ha followed by ripping to 30 cm depth then seeding was ineffective as successful seedling emergence was followed by over 90% seedling mortality which was 10-fold greater than seedling mortality in an uncontaminated reference site. High mortality was attributed to seedling roots being impededed as soil water was more than 3-fold greater at 5 to 40 cm depth in contaminated site than reference site. In response to high seedling mortality after emergence test pits were dug to 1 m deep to collect soil samples at 10 cm intervals for phytotoxicity testing and to measure soil pH-CaCl2, copper (DPTA ion extraction), electrical conductivity and gravimetric water content in three replicate pits at three replicate sites. Also, soil impedance was measured down the soil profile at 5 cm intervals at six replicate points/pit. For phytotoxicity testing soil samples were placed into three replicate plastic pots/sample and seeded with 10 seeds of Avena sativa and watered daily. Seedlings were harvested after at least two weeks after seedling emergence and rooting depth in pots measured. There was no difference in seedling emergence and survival of seedlings between contaminated and uncontaminated soil samples however mean seedling root growth was significantly lower in soil samples

  19. 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.

  20. [The international man-media Tessékéré (OHMi) Observatory: a research tool to study the complexity of arid ecosystems in Sahel].

    Science.gov (United States)

    Guissé, Aliou; Boëtsch, Gilles; Ducourneau, Axel; Goffner, Deborah; Gueye, Lamine

    2013-01-01

    In the Sahelian zone, the drought phenomenon, combined with anthropic factors (monoculture, bush fires, defect or deficit of manure, overgrazing, etc.), has seriously affected ecological great balances, involving a degradation of the natural resources as well as a fall in agricultural productions, pointing to a process of desertification. To face these challenges, in the course of the 8th ordinary session of the conference of the Heads of States of the African Union held in January 2007 in Addis Ababa (Ethiopia), 11 countries adopted the Panafrican project called the Green Great Wall (GGW). The total objective of the GGW is to contribute i) to the fight against the desert's advance, ii) to the development of the Saharan-Sahelian zones toward a durable management of the natural resources, and iii) to the fight against poverty. It deals with the construction of a set of zones of afforestation crossing the whole African continent in the long term (7000km of which are in the west). Even if some decisions in the launching phase the GGW must be taken quickly, one cannot do without investment in interdisciplinary research. In particular, associating fundamental research and applied research will allow us to ensure the success in the medium and long term of such a large-scale reforestation project. Research segmented in compartmentalized knowledge fields needed to get adequate tools, among which OHMi Tessékéré, initiated by INNEE (Centre national de la recherche scientifique [CNRS]), in partnership with UCAD, constitutes an example. This suitable scientific tool, capable of action flexibility, of self-financing capacity, anchored in civil society, ready to implement a pragmatic and local interdisciplinarity founded currently on the concept of socio-ecological system (SES), is the one we chose to conduct our studies on the Ferlo arid ecosystems. Copyright © 2013 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  1. Significant Impacts of Increasing Aridity on the Arid Soil Microbiome.

    Science.gov (United States)

    Neilson, Julia W; Califf, Katy; Cardona, Cesar; Copeland, Audrey; van Treuren, Will; Josephson, Karen L; Knight, Rob; Gilbert, Jack A; Quade, Jay; Caporaso, J Gregory; Maier, Raina M

    2017-01-01

    Global deserts occupy one-third of the Earth's surface and contribute significantly to organic carbon storage, a process at risk in dryland ecosystems that are highly vulnerable to climate-driven ecosystem degradation. The forces controlling desert ecosystem degradation rates are poorly understood, particularly with respect to the relevance of the arid-soil microbiome. Here we document correlations between increasing aridity and soil bacterial and archaeal microbiome composition along arid to hyperarid transects traversing the Atacama Desert, Chile. A meta-analysis reveals that Atacama soil microbiomes exhibit a gradient in composition, are distinct from a broad cross-section of nondesert soils, and yet are similar to three deserts from different continents. Community richness and diversity were significantly positively correlated with soil relative humidity (SoilRH). Phylogenetic composition was strongly correlated with SoilRH, temperature, and electrical conductivity. The strongest and most significant correlations between SoilRH and phylum relative abundance were observed for Acidobacteria, Proteobacteria, Planctomycetes, Verrucomicrobia, and Euryarchaeota (Spearman's rank correlation [rs] = >0.81; false-discovery rate [q] = ≤0.005), characterized by 10- to 300-fold decreases in the relative abundance of each taxon. In addition, network analysis revealed a deterioration in the density of significant associations between taxa along the arid to hyperarid gradient, a pattern that may compromise the resilience of hyperarid communities because they lack properties associated with communities that are more integrated. In summary, results suggest that arid-soil microbiome stability is sensitive to aridity as demonstrated by decreased community connectivity associated with the transition from the arid class to the hyperarid class and the significant correlations observed between soilRH and both diversity and the relative abundances of key microbial phyla typically

  2. Marine Ecosystems Analysis (MESA) Program, New York Bight Surficial Sediment Analyses

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Marine Ecosystems Analysis (MESA) Program, New York Bight Study was funded by NOAA and the Bureau of Land Management (BLM). The Atlas was a historical...

  3. Optimal method of ecological restoration of degraded ecosystem using goal programming

    Science.gov (United States)

    Sun, Ling; Zhu, Zesheng

    2017-08-01

    Ecological restoration of degraded wetland ecosystem can be achieved by planning experts according to ground investigation, but with low efficiencies. We report that satellite sensors, maximizing ecosystem service values and minimizing ecological restoration cost improve ecological restoration efficiency. In particular, linear goal programming (LGP), an optimal programming, improves ecological restoration efficiency by more than 250% in the return on investment of ecological restoration, using TM satellite as area sensors. LGP also enables efficient introduction of optimal management into ecological restoration of degraded wetland ecosystem.

  4. Seasonality of soil moisture mediates responses of ecosystem phenology to elevated CO2 and warming in a semi‐arid grassland

    National Research Council Canada - National Science Library

    Zelikova, Tamara J; Williams, David G; Hoenigman, Rhonda; Blumenthal, Dana M; Morgan, Jack A; Pendall, Elise; Guo, Dali

    2015-01-01

    .... We used repeat photography and a novel means of quantifying greenness in digital photographs to assess how the individual and combined effects of warming and elevated CO 2 impact ecosystem phenology...

  5. Predictive Mapping of Dwarf Shrub Vegetation in an Arid High Mountain Ecosystem Using Remote Sensing and Random Forests

    Directory of Open Access Journals (Sweden)

    Kim André Vanselow

    2014-07-01

    Full Text Available In many arid mountains, dwarf shrubs represent the most important fodder and firewood resources; therefore, they are intensely used. For the Eastern Pamirs (Tajikistan, they are assumed to be overused. However, empirical evidence on this issue is lacking. We aim to provide a method capable of mapping vegetation in this mountain desert. We used random forest models based on remote sensing data (RapidEye, ASTER GDEM and 359 plots to predictively map total vegetative cover and the distribution of the most important firewood plants, K. ceratoides and A. leucotricha. These species were mapped as present in 33.8% of the study area (accuracy 90.6%. The total cover of the dwarf shrub communities ranged from 0.5% to 51% (per pixel. Areas with very low cover were limited to the vicinity of roads and settlements. The model could explain 80.2% of the total variance. The most important predictor across the models was MSAVI2 (a spectral vegetation index particularly invented for low-cover areas. We conclude that the combination of statistical models and remote sensing data worked well to map vegetation in an arid mountainous environment. With this approach, we were able to provide tangible data on dwarf shrub resources in the Eastern Pamirs and to relativize previous reports about their extensive depletion.

  6. Adaptive management of large aquatic ecosystem recovery programs in the United States.

    Science.gov (United States)

    Thom, Ronald; St Clair, Tom; Burns, Rebecca; Anderson, Michael

    2016-12-01

    Adaptive management (AM) is being employed in a number of programs in the United States to guide actions to restore aquatic ecosystems because these programs are both expensive and are faced with significant uncertainties. Many of these uncertainties are associated with prioritizing when, where, and what kind of actions are needed to meet the objectives of enhancing ecosystem services and recovering threatened and endangered species. We interviewed nine large-scale aquatic ecosystem restoration programs across the United States to document the lessons learned from implementing AM. In addition, we recorded information on ecological drivers (e.g., endangered fish species) for the program, and inferred how these drivers reflected more generic ecosystem services. Ecosystem services (e.g., genetic diversity, cultural heritage), albeit not explicit drivers, were either important to the recovery or enhancement of the drivers, or were additional benefits associated with actions to recover or enhance the program drivers. Implementing programs using AM lessons learned has apparently helped achieve better results regarding enhancing ecosystem services and restoring target species populations. The interviews yielded several recommendations. The science and AM program must be integrated into how the overall restoration program operates in order to gain understanding and support, and effectively inform management decision-making. Governance and decision-making varied based on its particular circumstances. Open communication within and among agency and stakeholder groups and extensive vetting lead up to decisions. It was important to have an internal agency staff member to implement the AM plan, and a clear designation of roles and responsibilities, and long-term commitment of other involved parties. The most important management questions and information needs must be identified up front. It was imperative to clearly identify, link and continually reinforce the essential

  7. USGS Science for Restoration of South Florida: The South Florida Ecosystem Program

    Science.gov (United States)

    McPherson, Benjamin F.; Gerould, Sarah; Higer, Aaron L.

    1999-01-01

    As land and resource managers see the value of their resources diminish, and the public watches the environments they knew as children become degraded, there are increasing calls to restore what has been lost, or to build productive ecosystems that will be healthy and sustainable under the conditions of human use. The U.S. Geological Survey's (USGS) Placed-Based Studies Program was established to provide sound science for resource managers in critical ecosystems such as South Florida (fig. 1). The program, which began in south Florida in 1995, provides relevant information, high-quality data, and models to support decisions for ecosystem restoration and management. The program applies multi- and interdisciplinary science to address regional and subregional environmental resources issues.

  8. Nature as capital: Advancing and incorporating ecosystem services in United States federal policies and programs.

    Science.gov (United States)

    Schaefer, Mark; Goldman, Erica; Bartuska, Ann M; Sutton-Grier, Ariana; Lubchenco, Jane

    2015-06-16

    The concept of nature as capital is gaining visibility in policies and practices in both the public and private sectors. This change is due to an improved ability to assess and value ecosystem services, as well as to a growing recognition of the potential of an ecosystem services approach to make tradeoffs in decision making more transparent, inform efficient use of resources, enhance resilience and sustainability, and avoid unintended negative consequences of policy actions. Globally, governments, financial institutions, and corporations have begun to incorporate natural capital accounting in their policies and practices. In the United States, universities, nongovernmental organizations, and federal agencies are actively collaborating to develop and apply ecosystem services concepts to further national environmental and economic objectives. Numerous federal agencies have begun incorporating these concepts into land use planning, water resources management, and preparations for, and responses to, climate change. Going forward, well-defined policy direction will be necessary to institutionalize ecosystem services approaches in federal agencies, as well as to guide intersector and interdisciplinary collaborative research and development efforts. In addition, a new generation of decision support tools are needed to further the practical application of ecosystem services principles in policymaking and commercial activities. Improved performance metrics are needed, as are mechanisms to monitor the status of ecosystem services and assess the environmental and economic impacts of policies and programs. A greater national and international financial commitment to advancing ecosystem services and natural capital accounting would likely have broad, long-term economic and environmental benefits.

  9. Networks Analysis of a Regional Ecosystem of Afterschool Programs

    Science.gov (United States)

    Russell, Martha G.; Smith, Marc A.

    2011-01-01

    Case studies have documented the impact of family-school-community collaboration in afterschool programs on increasing awareness about the problems of at-risk youth, initiating dialogue among leaders and community representatives, developing rich school-based information systems, and demonstrating how to build strong relationships between public…

  10. Stop and smell the flowers: Herbaceous understory significantly contributes to woodland carbon and water fluxes in a semi-arid ecosystem 2025

    Science.gov (United States)

    Changes in vegetation structure in pulse-driven, water-limited systems can have important and non-linear affects on ecosystem function and biogeochemical cycling. Conversion of grasslands to woodlands in these systems through woody plant encroachment also results in greater patch heterogeneity, and ...

  11. A County-Level Program to Assess Farming System Ecosystem Services

    Energy Technology Data Exchange (ETDEWEB)

    Capece, John

    2012-12-12

    The survival of Florida’s biodiversity and economy is dependent on finding ways to balance farm economics with proper management of water and other natural resources. Taking on this challenge of maximizing the delivery of ecosystems services from agricultural production systems is the mandate of the Hendry County Sustainable Biofuels Center. Given that sea level rise is the overarching, long-term threat to the south Florida and its ecosystems, the most valuable ecosystems services for the state of Florida are those that mitigate climate change. Biofuels are put forward as one approach to forestalling climate change, but its value as an industry in providing this and other ecosystem services is unproven. The Sustainable Biofuels Center has developed a set of programs to both document and enhance the ecosystems services values of the evolving Florida biofuels industry. The Center engages in agricultural systems evaluation, sustainability indexing and sustainability research. Methods employed for documenting ecosystems services and costs include Life Cycle Assessment, Emergy Analysis, and optimization of cost-benefit functions. Radically new farming and economic compensation systems must be created and implemented if we are to achieve a successful agricultural business model built upon balanced revenue streams from these varied services. Accordingly, the Center also supports field research and demonstration projects to document the capacity for innovative farming systems to deliver ecosystems services such as water storage. To help promote the inclusion of ecosystems services considerations in farm operations, the program includes curriculum development at both the K-12 and college level, as well as programs to bring diverse stakeholders in to collaborative visioning process. Lastly, since county governments are often the level where new industry seek entry to the landscape, the Center is also developing metrics and tools through which economic development officers

  12. Aridity and hominin environments

    Science.gov (United States)

    Blumenthal, Scott A.; Levin, Naomi E.; Brown, Francis H.; Brugal, Jean-Philip; Chritz, Kendra L.; Harris, John M.; Jehle, Glynis E.; Cerling, Thure E.

    2017-07-01

    Aridification is often considered a major driver of long-term ecological change and hominin evolution in eastern Africa during the Plio-Pleistocene; however, this hypothesis remains inadequately tested owing to difficulties in reconstructing terrestrial paleoclimate. We present a revised aridity index for quantifying water deficit (WD) in terrestrial environments using tooth enamel δ18O values, and use this approach to address paleoaridity over the past 4.4 million years in eastern Africa. We find no long-term trend in WD, consistent with other terrestrial climate indicators in the Omo-Turkana Basin, and no relationship between paleoaridity and herbivore paleodiet structure among fossil collections meeting the criteria for WD estimation. Thus, we suggest that changes in the abundance of C4 grass and grazing herbivores in eastern Africa during the Pliocene and Pleistocene may have been decoupled from aridity. As in modern African ecosystems, other factors, such as rainfall seasonality or ecological interactions among plants and mammals, may be important for understanding the evolution of C4 grass- and grazer-dominated biomes.

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

    Science.gov (United States)

    Delgado-Baquerizo, Manuel; Maestre, Fernando T; Gallardo, Antonio; Quero, José L; Ochoa, Victoria; García-Gómez, Miguel; Escolar, Cristina; García-Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Gozalo, Beatriz; Noumi, Zouhaier; Derak, Mchich; Wallenstein, Matthew D

    2013-01-01

    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.

  14. 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.

  15. Spatio-temporal dynamics of soil water in a semi-arid Mediterranean ecosystem: implications for plant dynamics and spatial pattern.

    Science.gov (United States)

    Pueyo, Yolanda; Moret-Fernández, David; Arroyo, Antonio I.; de Frutos, Ángel; Saiz, Hugo; Alados, Concepción L.

    2014-05-01

    Soil water presents high temporal and spatial variability in drylands. The temporal variability is determined by the heterogeneous and unpredictable rainfall pattern in these ecosystems. The spatial variability is associated to the well-known "source-sink" eco-hydrological dynamics occurring in drylands, related to the patchy vegetation and bare soil structure with water run-off generated on the bare soil patches and water infiltration preferentially into vegetated areas. These run-off - run-on systems has been extensively studied and the processes involved are well known, including the role of different plant types capturing the water run-on, increasing infiltration and reducing evaporation under plant canopies. However, integrative studies of hydrological and ecological processes in a whole ecosystem during a prolonged time period are scarce, despite the relevance of this approach to understand the role of hydrological processes (and what hydrological process are most important) determining plant dynamics and spatial pattern. We present an eco-hydrological study conducted in a semiarid Mediterranean ecosystem in the Middle Ebro Valley (NE Spain), where soil water content and patterns of plant establishment were followed during 30 months in 4 microsites: open bare areas, under two shrub species (Salsola vermiculata and Artemisia herba-alba) and one perennial grass species (Lygeum spartum). These 4 microsites represent the vast majority of the land in the ecosystem under study. Water infiltration, photosynthetic photon flux and soil temperature were also recorded in the 4 microsites. Simultaneously, seedling establishment and survival were recorded twice per year in the same microsites. Lygeum spartum was the microsite with the largest increment in water infiltration, and with the largest reduction in both solar radiation and soil temperature when compared with the measurement in the open bare areas. However, soil water content after rainfall under the canopy of

  16. 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

    uses in the studied landscape by developing a typology of farmers. It also investigates how farmers respond to future changes that potentially affect their farming and describes potential future trajectories of agriculture in the area and the implications for agro-ecosystem services provision. Stage 3...... configuration. The changes involved three major trajectories (forest expansion, abandonment of rain-fed farming, and intensification) and were attributable to various interacting biophysical and socioeconomic drivers. The study differentiates six types of farmers according to the characteristics...

  17. Using vegetation structure estimates derived from multi-source remote sensing to predict dynamics of a semi-arid ecosystem in the western US

    Science.gov (United States)

    Shrestha, R.; Mitchell, J. J.; Glenn, N. F.; Flores, A. N.

    2014-12-01

    The distribution of species and vegetation types across the western US are expected to shift in response to climate change. Previous studies have documented the change in fire regime and the increasing fire-invasive grass cycle occurring in the western U.S. The change in vegetation structure due to climate change and invasive species alters the fuel load, making these ecosystems vulnerable to high-severity fire. Synergistic remote sensing data, such as hyperspectral data and high-resolution lidar, can be leveraged to capture the composition and structural variability of short-statured semiarid vegetation (e.g. sagebrush, annual grasses). We use a random-forests based fusion technique to integrate multi-source airborne data (hyperspectral and LiDAR) and generate spatially-explicit estimates of vegetation composition and structure (biomass, cover, density, height, LAI) and associated uncertainty across a climate and elevation gradient in southern Idaho. The results will be used to initialize an individual-based terrestrial biosphere model (Ecosystem Demography, ED2) and estimate structural dynamics under future scenarios. This study will provide a basis for understanding feedback mechanisms related to changing climate conditions, fire regimes and patterns of non-native plant invasion. The forthcoming field and remote sensing collection campaigns are also designed for parameterizing a dryland shrub plant functional type in the ED2 model.

  18. Transfer of {sup 137}Cs in Zea mays and Phaseolus vulgaris in a semi-arid ecosystem; Transferencia de {sup 137}Cs en Zea mays y Phaseolus vulgaris en un ecosistema semiarido

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes, M.L.; Segovia, N.; Gaso P, M.I.; Palacios, J.C. [Instituto Nacional de Investigaciones Nucleares, Laboratorio de Vigilancia Radiologica Ambiental, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1999-07-01

    With the objective to analyse the transference of {sup 137} Cs from soil to plants, it is realized a study in maize and bean plants in the Radioactive Waste Storage Center (CADER). This site is located in a semi-arid region with a characteristic vegetation of a sub humid temperature zone. So those plants maize and beans were cultivated in four zones near CADER during a four years period. The obtained results for 1991 to 1994 for {sup 137} Cs in soil samples for those zones showed an evident contamination in zone 1, due to a rupture of an industrial source. In 1994 the effect of decontamination was evident since the values of specific activity found in roots were around magnitude lesser than found in 1992. In spite of exhaustive studies have been reported about the transference factors for {sup 137} Cs in different agricultural foods, relatively few of them have paid attention to the interactions between cereals and leguminous associated in semiarid ecosystems. (Author)

  19. Impacts of Stream Flow and Climate Variability on Native and Invasive Woody Species in a Riparian Ecosystem of a Semi-Arid Region of the Great Plains, USA

    Science.gov (United States)

    Skolaut, K.; Awada, T.; Cherubini, P.; Schapaugh, A.

    2012-12-01

    Riparian ecosystems support diverse plant communities that exert direct and indirect biological, physical and chemical influence on, and are influenced by, adjacent water through both above and below-ground interactions. Historically, riparian areas of the northern Great Plains, US have been dominated by the native Populus deltoides (eastern cottonwood). This species relies on regular floods for regeneration and groundwater access for success. Over the past sixty years, changes in flow management and agricultural practices, coupled with climate variability and drought have altered stream flow and caused a dramatic decline in stream water yields and levels of groundwater. These and other biotic and biotic factors have promoted the expansion of the upland native woody species Juniperus virginiana (eastern redcedar), and the invasion of the non-native (introduced) Elaeagnus angustifolia (Russian olive) into riparian ecosystems. This invasion has further altered the water balance in the system and exasperated the problem of water scarcity with negative feedback on ecosystem services and growth of native woody species. The ability of P. deltoides to re-establish and grow is of concern for natural resource managers. Tree ring analysis of annual growth rates were used to determine 1) the responses P. deltoides and invasive J. virginiana and E. angustifulia to climate variability and stream flow regulation, and 2) the impacts of the two invasive species on the growth of native P. deltoides. Results show a dependency of growth for P. deltoides on the previous year summer temperature, and a less significant correlation to annual stream flow. J. virginiana showed the highest correlation to annual stream flow, as well as some dependency on the previous growing season precipitation. While the growth of both P. deltoides and J. virginiana displayed greater dependence on climatic factors, E. angustifolia displayed the lowest mean basal area growth and deviation from the growth. E

  20. Development of vegetation based soil quality indices for mineralized terrane in arid and semi-arid regions

    Science.gov (United States)

    S. W. Blecker; L. L. Stillings; M. C. Amacher; J. A. Ippolito; N. M. DeCrappeo

    2012-01-01

    Soil quality indices (SQIs) are often management driven and attempt to describe key relationships between above- and below-ground parameters. In terrestrial systems, indices that were initially developed and modified for agroecosystems have been applied to non-agricultural systems in increasing number. We develop an SQI in arid and semi-arid ecosystems of the Western...

  1. Assessment of Downscaling Planetary Boundaries to Semi-Arid Ecosystems with a Local Perception: A Case Study in the Middle Reaches of Heihe River

    Directory of Open Access Journals (Sweden)

    Heng Yi Teah

    2016-11-01

    Full Text Available The middle reaches of Heihe River are located in the oasis of the Gobi Desert where limited freshwater supply supports more than 1.5 million inhabitants. The intense agricultural activities are depleting the groundwater reserve. Consequently, natural landscapes and habitats are degraded. Though such development improves the livelihood of the local community, long-term sustainability of the ecosystem is at risk. Local authorities must be informed holistically to prepare for adapting to the changes and/or mitigating the impacts. The purpose of this study was to perform a regional sustainability assessment based on downscaling the planetary boundaries (PBs. We proposed a regional safe operating space framework that applied a top-down approach using the environmental monitoring data, and a bottom-up approach using knowledge from the local perception about environmental disaster. We conducted on-site samplings and interviews of residents to demonstrate the method. Overall, we showed that the middle reaches had transgressed the safe operating space, particularly on the freshwater use and biogeochemical flow dimensions. We found that the local perception acquired from interviews complemented the insufficiency of the monitoring data and provided the insightful social implications of transgressing the safe operating space, i.e., the anticipated impacts on local livelihood, for policy support.

  2. Arid Zone Hydrology

    Science.gov (United States)

    Arid zone hydrology encompasses a wide range of topics and hydro-meteorological and ecological characteristics. Although arid and semi-arid watersheds perform the same functions as those in humid environments, their hydrology and sediment transport characteristics cannot be readily predicted by inf...

  3. Effects of land use and climate change on ecosystem services in Central Asia's arid regions: A case study in Altay Prefecture, China.

    Science.gov (United States)

    Fu, Qi; Li, Bo; Hou, Ying; Bi, Xu; Zhang, Xinshi

    2017-12-31

    The sustainable use of ecosystem services (ES) can contribute to enhancing human well-being. Understanding the effects of land use and climate change on ES can provide scientific and targeted guidance for the sustainable use of ES. The objective of this study was to reveal the way in which land use and climate change influence the spatial and temporal variations of ES in the mountain-oasis-desert system (MODS). In this study, we assessed water yield, soil conservation, crop production, and sand fixation in 1990, 2000, and 2010 in Altay Prefecture, which is representative of the MODS, based on widely used biophysical models. Moreover, we analyzed the effects of different land use and climate change conditions on ES. The results show that the area of forest and bare land decreased in Altay Prefecture. In contrast, the area of grassland with low coverage and cropland increased. The climate of this area presented an overall warming-wetting trend, with warming-drying and cooling-wetting phenomena in some areas. Soil conservation in the mountain zone, water yield in the oasis zone, and sand fixation in the desert zone all decreased under the influence of land use change alone. The warming-drying trend led to decreased water yield in the oasis zone and increased wind erosion in the desert zone. Based on the results, we recommend that local governments achieve sustainable use of ES by planting grasslands with high coverage in the oasis zone, increasing investment in agricultural science and technology, and establishing protected areas in the mountain and desert zones. The methodology in our study can also be applied to other regions with a MODS structure. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. A machine learning approach to estimation of downward solar radiation from satellite-derived data products: An application over a semi-arid ecosystem in the U.S.

    Science.gov (United States)

    Zhou, Qingtao; Flores, Alejandro; Glenn, Nancy F; Walters, Reggie; Han, Bangshuai

    2017-01-01

    Shortwave solar radiation is an important component of the surface energy balance and provides the principal source of energy for terrestrial ecosystems. This paper presents a machine learning approach in the form of a random forest (RF) model for estimating daily downward solar radiation flux at the land surface over complex terrain using MODIS (MODerate Resolution Imaging Spectroradiometer) remote sensing data. The model-building technique makes use of a unique network of 16 solar flux measurements in the semi-arid Reynolds Creek Experimental Watershed and Critical Zone Observatory, in southwest Idaho, USA. Based on a composite RF model built on daily observations from all 16 sites in the watershed, the model simulation of downward solar radiation matches well with the observation data (r2 = 0.96). To evaluate model performance, RF models were built from 12 of 16 sites selected at random and validated against the observations at the remaining four sites. Overall root mean square errors (RMSE), bias, and mean absolute error (MAE) are small (range: 37.17 W/m2-81.27 W/m2, -48.31 W/m2-15.67 W/m2, and 26.56 W/m2-63.77 W/m2, respectively). When extrapolated to the entire watershed, spatiotemporal patterns of solar flux are largely consistent with expected trends in this watershed. We also explored significant predictors of downward solar flux in order to reveal important properties and processes controlling downward solar radiation. Based on the composite RF model built on all 16 sites, the three most important predictors to estimate downward solar radiation include the black sky albedo (BSA) near infrared band (0.858 μm), BSA visible band (0.3-0.7 μm), and clear day coverage. This study has important implications for improving the ability to derive downward solar radiation through a fusion of multiple remote sensing datasets and can potentially capture spatiotemporally varying trends in solar radiation that is useful for land surface hydrologic and terrestrial

  5. A machine learning approach to estimation of downward solar radiation from satellite-derived data products: An application over a semi-arid ecosystem in the U.S.

    Directory of Open Access Journals (Sweden)

    Qingtao Zhou

    Full Text Available Shortwave solar radiation is an important component of the surface energy balance and provides the principal source of energy for terrestrial ecosystems. This paper presents a machine learning approach in the form of a random forest (RF model for estimating daily downward solar radiation flux at the land surface over complex terrain using MODIS (MODerate Resolution Imaging Spectroradiometer remote sensing data. The model-building technique makes use of a unique network of 16 solar flux measurements in the semi-arid Reynolds Creek Experimental Watershed and Critical Zone Observatory, in southwest Idaho, USA. Based on a composite RF model built on daily observations from all 16 sites in the watershed, the model simulation of downward solar radiation matches well with the observation data (r2 = 0.96. To evaluate model performance, RF models were built from 12 of 16 sites selected at random and validated against the observations at the remaining four sites. Overall root mean square errors (RMSE, bias, and mean absolute error (MAE are small (range: 37.17 W/m2-81.27 W/m2, -48.31 W/m2-15.67 W/m2, and 26.56 W/m2-63.77 W/m2, respectively. When extrapolated to the entire watershed, spatiotemporal patterns of solar flux are largely consistent with expected trends in this watershed. We also explored significant predictors of downward solar flux in order to reveal important properties and processes controlling downward solar radiation. Based on the composite RF model built on all 16 sites, the three most important predictors to estimate downward solar radiation include the black sky albedo (BSA near infrared band (0.858 μm, BSA visible band (0.3-0.7 μm, and clear day coverage. This study has important implications for improving the ability to derive downward solar radiation through a fusion of multiple remote sensing datasets and can potentially capture spatiotemporally varying trends in solar radiation that is useful for land surface hydrologic and

  6. 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. 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 model approach within a value chain analysis process to evaluate program effectiveness and impacts at both formative and summative levels. 7. Disseminate lessons learned, and results achieved to the international community through all recognized knowledge sharing outlets. Goal and objectives - accomplished by implementation of a variety of integrated action steps each linked to specific performance impact measures that assess short, medium, and long-term impacts (modified logic model). Impact

  7. The Oncor Geodatabase for the Columbia Estuary Ecosystem Restoration Program: Annual Report, 2012

    Energy Technology Data Exchange (ETDEWEB)

    Coleman, Andre M.; Johnson, Gary E.; Borde, Amy B.; Diefenderfer, Heida L.; Sather, Nichole K.; Seiple, Timothy E.; Serkowski, John A.

    2013-11-10

    Pacific Northwest National Laboratory (PNNL) conducted this project for the U.S. Army Corps of Engineers, Portland District (Corps). The purpose of the project is to develop a geospatial, web-accessible database (called “Oncor”) for action effectiveness and related data from monitoring and research efforts for the Columbia Estuary Ecosystem Restoration Program (CEERP). The intent is for the Oncor database to enable synthesis and evaluation, the results of which can then be applied in subsequent CEERP decision-making. This is the first annual report in what is expected to be a 3- to 4-year project, which commenced on February 14, 2012.

  8. The centrality of meta-programming in the ES-DOC eco-system

    Science.gov (United States)

    Greenslade, Mark

    2017-04-01

    The Earth System Documentation (ES-DOC) project is an international effort aiming to deliver a robust earth system model inter-comparison project documentation infrastructure. Such infrastructure both simplifies & standardizes the process of documenting (in detail) projects, experiments, models, forcings & simulations. In support of CMIP6, ES-DOC has upgraded its eco-system of tools, web-services & web-sites. The upgrade consolidates the existing infrastructure (built for CMIP5) and extends it with the introduction of new capabilities. The strategic focus of the upgrade is improvements in the documentation experience and broadening the range of scientific use-cases that the archived documentation may help deliver. Whether it is highlighting dataset errors, exploring experimental protocols, comparing forcings across ensemble runs, understanding MIP objectives, reviewing citations, exploring component properties of configured models, visualising inter-model relationships, scientists involved in CMIP6 will find the ES-DOC infrastructure helpful. This presentation underlines the centrality of meta-programming within the ES-DOC eco-system. We will demonstrate how agility is greatly enhanced by taking a meta-programming approach to representing data models and controlled vocabularies. Such an approach nicely decouples representations from encodings. Meta-models will be presented along with the associated tooling chain that forward engineers artefacts as diverse as: class hierarchies, IPython notebooks, mindmaps, configuration files, OWL & SKOS documents, spreadsheets …etc.

  9. GSD Update: Year in Review: Spotlight on 2013 research by the Grassland, Shrubland and Desert Ecosystems Science Program

    Science.gov (United States)

    Deborah M. Finch

    2014-01-01

    In this issue of the GSD Update, we take a look back at selected studies of the Grassland, Shrubland and Desert Ecosystems Science Program (GSD) that depict its strengths and focus areas. Significant results of recent research and science delivery by GSD scientists are highlighted. We feature program research that lines up with the strategic research priorities of the...

  10. GSD Update: Year in Review: Spotlight on 2016 Research by the Grassland, Shrubland and Desert Ecosystems Science Program

    Science.gov (United States)

    Deborah M. Finch

    2017-01-01

    In this issue of the GSD Update, we take a look back at selected studies of the Grassland, Shrubland and Desert Ecosystems Science Program (GSD) that depict its strengths and focus areas. Significant results of recent research and science delivery by GSD scientists are highlighted. We feature program research that lines up with the strategic priorities of the USDA...

  11. A Linear Programming Model to Biophysically Assess Some Ecosystem Service Synergies and Trade-Offs in Two Irish Landscapes

    Directory of Open Access Journals (Sweden)

    Edwin Corrigan

    2016-06-01

    Full Text Available Ecosystem service provisions are becoming more frequently used to assess land-use related conflicts in recent decades. This study investigates the current spatial and research information available to quantify ecosystem services relative to forest land-use planning in Ireland. A model is developed using the linear-programming method in Remsoft’s Woodstock platform. This model is applied to two case study areas in Ireland: Western Peatlands and Newmarket. Each case study area was chosen to assess a unique issue in the Irish and European context on the provision of ecosystem services. Western Peatlands was chosen to assess the effects of forest and alternative land-use options and Newmarket was chosen to investigate the effect of afforestation. The synergies and trade-offs of biophysically optimising the provisions of each ecosystem service are presented and discussed. The study quantitatively determines that trade-offs among provisions of some ecosystem services are required when optimising an ecosystem service while other ecosystem services are synergistic when the provision of a single ecosystem service is optimised.

  12. Ecological restoration of groundwater-dependent vegetation in the arid Ejina Delta: evidences from satellite evapotranspiration

    Science.gov (United States)

    Kai, Lu; Garcia, Monica; Yu, Jingjie; Zhang, Yichi; Wang, Ping; Wang, Sheng; Liu, Xiao

    2017-04-01

    The ecological water conveyance project (EWCP) in the Ejina delta, a typical hyper-arid area of China, aimed to restore degraded phreatophytic ecosystems. We assessed the degree of ecosystem recovery using as an ecohydrological indicator a ratio between actual and potential evapotranspiration derived from MODIS since the beginning of the project in 2001. The selected indicator was the Temperature Vegetation Dryness Index (TVDI) which was validated with Eddy covariance (EC) data confirming its applicability to monitor groundwater dependent vegetation. The spatial analyses of the evapotranspiration ratio show drying trends (2000-2015) which are stronger and also cover larger extensions than the wetting trends. Thus, the condition of key riparian areas relying mostly on surface water improved since the project began. However, groundwater dependent ecosystems located in lower river Xihe reaches present drying trends. It seems that despite of the runoff supplemented by the EWCP project, there is nowadays more inequality in the access to water by groundwater dependent ecosystems in the Ejina Delta. The study shows that energy-evaporation indices, relying on radiometric satellite temperature like the TVDI, can detect degradation signals that otherwise might go undetected by NDVI analyses especially in arid regions, where vegetation indices are greatly affected by the soil background signals. Additionally, they can provide timely information to water managers on how much water to allocate for a sustainable restoration program.

  13. Lower Columbia River and Estuary Ecosystem Restoration Program Reference Site Study: 2011 Restoration Analysis - FINAL REPORT

    Energy Technology Data Exchange (ETDEWEB)

    Borde, Amy B.; Cullinan, Valerie I.; Diefenderfer, Heida L.; Thom, Ronald M.; Kaufmann, Ronald M.; Zimmerman, Shon A.; Sagar, Jina; Buenau, Kate E.; Corbett, C.

    2012-05-31

    The Reference Site (RS) study is part of the research, monitoring, and evaluation (RME) effort developed by the Action Agencies (Bonneville Power Administration [BPA], U.S. Army Corps of Engineers, Portland District [USACE], and U.S. Bureau of Reclamation) in response to Federal Columbia River Power System (FCRPS) Biological Opinions (BiOp). While the RS study was initiated in 2007, data have been collected at relatively undisturbed reference wetland sites in the LCRE by PNNL and collaborators since 2005. These data on habitat structural metrics were previously summarized to provide baseline characterization of 51 wetlands throughout the estuarine and tidal freshwater portions of the 235-km LCRE; however, further analysis of these data has been limited. Therefore, in 2011, we conducted additional analyses of existing field data previously collected for the Columbia Estuary Ecosystem Restoration Program (CEERP) - including data collected by PNNL and others - to help inform the multi-agency restoration planning and ecosystem management work underway in the LCRE.

  14. The Oncor Geodatabase for the Columbia Estuary Ecosystem Restoration Program: Handbook of Data Reduction Procedures, Workbooks, and Exchange Templates

    Energy Technology Data Exchange (ETDEWEB)

    Sather, Nichole K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Borde, Amy B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Diefenderfer, Heida L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Serkowski, John A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Coleman, Andre M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Johnson, Gary E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-12-01

    This Handbook of Data Reduction Procedures, Workbooks, and Exchange Templates is designed to support the Oncor geodatabase for the Columbia Estuary Ecosystem Restoration Program (CEERP). The following data categories are covered: water-surface elevation and temperature, sediment accretion rate, photo points, herbaceous wetland vegetation cover, tree plots and site summaries, fish catch and density, fish size, fish diet, fish prey, and Chinook salmon genetic stock identification. The handbook is intended for use by scientists collecting monitoring and research data for the CEERP. The ultimate goal of Oncor is to provide quality, easily accessible, geospatial data for synthesis and evaluation of the collective performance of CEERP ecosystem restoration actions at a program scale.

  15. Web-based ecosystem software for virtual crossmatching in transplant programs.

    Science.gov (United States)

    Aita, Keylla S U; Monte, Semiramis J H; Silva, Adalberto S; Marroquim, Mário S C; Coelho, Antônio Gilberto B; Sousa, Luiz Claudio D M

    2016-08-01

    The compatibilities between donors and recipients are extremely important for evaluating the immunological risks of transplants. One challenge faced by data analysis tools is the transformation of complex data into simple, intuitive, and important information that can be used to resolve contemporary problems. To address this challenge, we developed the EpViX software to perform epitope reactivity analyses and automated epitope virtual crossmatching. EpViX is a facilitator of medical decision-making regarding the identification of the best donor for a high-immunologic risk recipient. The objective of this work is to describe the computational architecture of the EpViX ecosystem (http://www.epvix.com.br). EpViX is a freeware on the web that was developed in the Ruby language. EpViX can be accessed from different platforms, e.g., PCs, tablets, and smartphones. It consists of an ecosystem of tools that are capable of integrating all of the stakeholders who are involved in a transplant process with a deceased donor. We successfully developed a program that allows people to work collaboratively and effectively during the donation process by accurately predicting negative crossmatches, saving time and other resources. EpViX represents a significant breakthrough for the organ transplant process and may meet the current needs of transplant programs because it increases the chances of the allocation of low-immunologic risk donors to highly sensitized recipients and assures greater equity among the recipients on a waiting list. EpViX was duly verified and tested in terms of data security. Moreover, usability tests demonstrated that EpViX is an intuitive and easy-to-use tool. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Participatory Goal Programming in Forest Management: An Application Integrating Several Ecosystem Services

    Directory of Open Access Journals (Sweden)

    Jorge Aldea

    2014-12-01

    Full Text Available In this study, we propose a procedure for integrating several ecosystem services into forest management by using the well-known multi-criteria approach called goal programming. It shows how interactions with various stakeholders are essential in order to choose the goal programming model applied, as well as some of its basic components (variant, targets, preferential weights, etc.. This methodology has been applied to a real forest management case where five criteria have been selected: timber production, wild edible mushroom production, carbon sequestration, net present value of the underlying investment, and a criterion associated with the sustainability of forest management defined by the idea of a normal forest. Given the characteristics of some of these criteria, such as mushroom production, the model has been developed in two scenarios: one deterministic and another with a Monte Carlo analysis. The results show a considerable degree of conflict between the proposed criteria. By applying several goal programming models, different Paretian efficient solutions were obtained. In addition, some results in Monte Carlo analysis for several criteria show notable variations. This fact is especially notable for the mushroom production criterion. Finally, the proposed approach seems attractive and can be directly applied to other forest management situations.

  17. Columbia Estuary Ecosystem Restoration Program: Restoration Design Challenges for Topographic Mounds, Channel Outlets, and Reed Canarygrass

    Energy Technology Data Exchange (ETDEWEB)

    Diefenderfer, Heida L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Borde, Amy B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sinks, Ian A. [Columbia Land Trust, Vancouver, WA (United States); Cullinan, Valerie I. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Zimmerman, Shon A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-08-31

    The purpose of this study was to provide science-based information to practitioners and managers of restoration projects in the Columbia Estuary Ecosystem Restoration Program (CEERP) regarding aspects of restoration techniques that currently pose known challenges and uncertainties. The CEERP is a program of the Bonneville Power Administration (BPA) and the U.S. Army Corps of Engineers (Corps), Portland District, in collaboration with the National Marine Fisheries Service and five estuary sponsors implementing restoration. The estuary sponsors are Columbia Land Trust, Columbia River Estuary Study Taskforce, Cowlitz Tribe, Lower Columbia Estuary Partnership, and Washington Department of Fish and Wildlife. The scope of the research conducted during federal fiscal year 2015 included three aspects of hydrologic reconnection that were selected based on available scientific information and feedback from restoration practitioners during project reviews: the design of mounds (also called hummocks, peninsulas, or berms); the control of reed canarygrass (Phalaris arundinaceae); and aspects of channel network design related to habitat connectivity for juvenile salmonids.

  18. ENSO elicits opposing responses of semi-arid vegetation between Hemispheres

    Science.gov (United States)

    Zhang, Anzhi; Jia, Gensuo; Epstein, Howard E.; Xia, Jiangjiang

    2017-01-01

    Semi-arid ecosystems are key contributors to the global carbon cycle and may even dominate the inter-annual variability (IAV) and trends of the land carbon sink, driven largely by the El Niño–Southern Oscillation (ENSO). The linkages between dynamics of semi-arid ecosystems and climate at the hemispheric scale however are not well known. Here, we use satellite data and climate observations from 2000 to 2014 to explore the impacts of ENSO on variability of semi-arid ecosystems, using the Ensemble Empirical Mode Decomposition method. We show that the responses of semi-arid vegetation to ENSO occur in opposite directions, resulting from opposing controls of ENSO on precipitation between the Northern Hemisphere (positively correlated to ENSO) and the Southern Hemisphere (negatively correlated to ENSO). Also, the Southern Hemisphere, with a robust negative coupling of temperature and precipitation anomalies, exhibits stronger and faster responses of semi-arid ecosystems to ENSO than the Northern Hemisphere. Our findings suggest that natural coherent variability in semi-arid ecosystem productivity responded to ENSO in opposite ways between two hemispheres, which may imply potential prediction of global semi-arid ecosystem variability, particularly based on variability in tropical Pacific Sea Surface Temperatures. PMID:28181570

  19. ENSO elicits opposing responses of semi-arid vegetation between Hemispheres.

    Science.gov (United States)

    Zhang, Anzhi; Jia, Gensuo; Epstein, Howard E; Xia, Jiangjiang

    2017-02-09

    Semi-arid ecosystems are key contributors to the global carbon cycle and may even dominate the inter-annual variability (IAV) and trends of the land carbon sink, driven largely by the El Niño-Southern Oscillation (ENSO). The linkages between dynamics of semi-arid ecosystems and climate at the hemispheric scale however are not well known. Here, we use satellite data and climate observations from 2000 to 2014 to explore the impacts of ENSO on variability of semi-arid ecosystems, using the Ensemble Empirical Mode Decomposition method. We show that the responses of semi-arid vegetation to ENSO occur in opposite directions, resulting from opposing controls of ENSO on precipitation between the Northern Hemisphere (positively correlated to ENSO) and the Southern Hemisphere (negatively correlated to ENSO). Also, the Southern Hemisphere, with a robust negative coupling of temperature and precipitation anomalies, exhibits stronger and faster responses of semi-arid ecosystems to ENSO than the Northern Hemisphere. Our findings suggest that natural coherent variability in semi-arid ecosystem productivity responded to ENSO in opposite ways between two hemispheres, which may imply potential prediction of global semi-arid ecosystem variability, particularly based on variability in tropical Pacific Sea Surface Temperatures.

  20. Increasing aridity reduces soil microbial diversity and abundance in global drylands

    OpenAIRE

    Maestre, Fernando T.; Delgado-Baquerizo, Manuel; Thomas C Jeffries; Eldridge, David J.; Ochoa, Victoria; Gozalo, Beatriz; Quero, José Luis; García-Gómez, Miguel; Gallardo, Antonio; Ulrich, Werner; Bowker, Matthew A.; Arredondo, Tulio; Barraza-Zepeda, Claudia; Bran, Donaldo; Florentino, Adriana

    2015-01-01

    Climate change is increasing the degree of aridity in drylands, which occupy 41% of Earth’s surface and support 38% of its population. Soil bacteria and fungi are largely responsible for key ecosystem services, including soil fertility and climate regulation, yet their responses to changes in aridity are poorly understood. Using a field survey conducted in drylands worldwide and DNA-sequencing approaches, we found that increases in aridity reduce the diversity and abundance of soil bacteria a...

  1. Analysis of aridity indicators in the Deliblato Sands

    Directory of Open Access Journals (Sweden)

    Kadović Ratko

    2014-01-01

    Full Text Available Deliblato Sands are located in the southern part of Banat region in Vojvodina province. According to the estimated changes of basic climate parameters in this part of the Republic of Serbia during past decades very strong rise in annual air temperatures (T was registered, an average of 0.52°C per decade. This rise in temperature increased the potential evapotranspiration (PET, which together with precipitation can increase the degree of aridity of climate in the study area. However, in the same period an increase in annual precipitation sum (P was observed, an average of about 35 mm per decade, which may somewhat slow the aridisation of desert sands. Considering the nature, origin and significance of Deliblato Sands ecosystem, the main goal of this paper is to analyse the drought and aridity index (AI = P / PET, analyse the trend of aridisation process and its possible impact on ecosystems of this special nature reserve. Aridity index analyses were performed in meteorological stations Banatski Karlovac, Vrsac and Bela Crkva for the period 1981 - 2010 at the annual values and for the growing season. Results showed that Deliblato desert sands (Banatski Karlovac stand at a higher frequency of arid years (AI < 0.65 compared to locations of Vrsac and Bela Crkva. On the other hand, the level of aridity has considerably increased during the vegetation period in desert sands as well in its surroundings. This intensified aridity is the result of considerable increase of potential evapotranspiration (PET connected to season precipitation.

  2. Waste biorefinery in arid/semi-arid regions.

    Science.gov (United States)

    Bastidas-Oyanedel, Juan-Rodrigo; Fang, Chuanji; Almardeai, Saleha; Javid, Usama; Yousuf, Ahasa; Schmidt, Jens Ejbye

    2016-09-01

    The utilization of waste biorefineries in arid/semi-arid regions is advisable due to the reduced sustainable resources in arid/semi-arid regions, e.g. fresh water and biomass. This review focuses on biomass residues available in arid/semi-arid regions, palm trees residues, seawater biomass based residues (coastal arid/semi-arid regions), and the organic fraction of municipal solid waste. The present review aims to describe and discuss the availability of these waste biomasses, their conversion to value chemicals by waste biorefinery processes. For the case of seawater biomass based residues it was reviewed and advise the use of seawater in the biorefinery processes, in order to decrease the use of fresh water. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Green Infrastructure for Arid Communities

    Science.gov (United States)

    how green infrastructure practices and the many associated benefits can be effective not only in wetter climates, but also for those communities in arid and semi-arid regions around the nation that have different precipitation patterns

  4. Reverse engineering model structures for soil and ecosystem respiration: the potential of gene expression programming

    Directory of Open Access Journals (Sweden)

    I. Ilie

    2017-09-01

    Full Text Available Accurate model representation of land–atmosphere carbon fluxes is essential for climate projections. However, the exact responses of carbon cycle processes to climatic drivers often remain uncertain. Presently, knowledge derived from experiments, complemented by a steadily evolving body of mechanistic theory, provides the main basis for developing such models. The strongly increasing availability of measurements may facilitate new ways of identifying suitable model structures using machine learning. Here, we explore the potential of gene expression programming (GEP to derive relevant model formulations based solely on the signals present in data by automatically applying various mathematical transformations to potential predictors and repeatedly evolving the resulting model structures. In contrast to most other machine learning regression techniques, the GEP approach generates readable models that allow for prediction and possibly for interpretation. Our study is based on two cases: artificially generated data and real observations. Simulations based on artificial data show that GEP is successful in identifying prescribed functions, with the prediction capacity of the models comparable to four state-of-the-art machine learning methods (random forests, support vector machines, artificial neural networks, and kernel ridge regressions. Based on real observations we explore the responses of the different components of terrestrial respiration at an oak forest in south-eastern England. We find that the GEP-retrieved models are often better in prediction than some established respiration models. Based on their structures, we find previously unconsidered exponential dependencies of respiration on seasonal ecosystem carbon assimilation and water dynamics. We noticed that the GEP models are only partly portable across respiration components, the identification of a general terrestrial respiration model possibly prevented by equifinality issues. Overall

  5. Reverse engineering model structures for soil and ecosystem respiration: the potential of gene expression programming

    Science.gov (United States)

    Ilie, Iulia; Dittrich, Peter; Carvalhais, Nuno; Jung, Martin; Heinemeyer, Andreas; Migliavacca, Mirco; Morison, James I. L.; Sippel, Sebastian; Subke, Jens-Arne; Wilkinson, Matthew; Mahecha, Miguel D.

    2017-09-01

    Accurate model representation of land-atmosphere carbon fluxes is essential for climate projections. However, the exact responses of carbon cycle processes to climatic drivers often remain uncertain. Presently, knowledge derived from experiments, complemented by a steadily evolving body of mechanistic theory, provides the main basis for developing such models. The strongly increasing availability of measurements may facilitate new ways of identifying suitable model structures using machine learning. Here, we explore the potential of gene expression programming (GEP) to derive relevant model formulations based solely on the signals present in data by automatically applying various mathematical transformations to potential predictors and repeatedly evolving the resulting model structures. In contrast to most other machine learning regression techniques, the GEP approach generates readable models that allow for prediction and possibly for interpretation. Our study is based on two cases: artificially generated data and real observations. Simulations based on artificial data show that GEP is successful in identifying prescribed functions, with the prediction capacity of the models comparable to four state-of-the-art machine learning methods (random forests, support vector machines, artificial neural networks, and kernel ridge regressions). Based on real observations we explore the responses of the different components of terrestrial respiration at an oak forest in south-eastern England. We find that the GEP-retrieved models are often better in prediction than some established respiration models. Based on their structures, we find previously unconsidered exponential dependencies of respiration on seasonal ecosystem carbon assimilation and water dynamics. We noticed that the GEP models are only partly portable across respiration components, the identification of a general terrestrial respiration model possibly prevented by equifinality issues. Overall, GEP is a promising

  6. Spatial and temporal characteristics of aridity conditions in Tarim Basin, China

    Science.gov (United States)

    Sun, Zhandong; Chang, Ni-Bin; Opp, Christian; Hennig, Thomas

    2010-10-01

    Arid ecosystems are very sensitive to a variety of physical, chemical and biological degradation processes. Tarim Basin, the biggest endorheic basin in the Central Asia continent, is considered as one of the least water-endowed regions in the world and arid and semi-arid environmental conditions are dominant. For the purposes of the convention, arid, semi-arid and dry sub-humid areas were defined as "areas, other than polar and sub-polar regions, in which the ratio of annual precipitation to potential evapotranspiration falls within the range from 0.05 to 0.65." In this study, the Aridity Index (AI), the ratio of precipitation and land surface temperature, was also adopted as the base method for determining dry land types and thereby delineating boundaries and showing changes of aridity conditions in Tarim Basin. Here, precipitation is from TRMM/PR, and land surface temperature is from Modis LST. To analyze the spatial and temporal variations of arid environmental conditions in Tarim basin, we calculated the yearly aridity index (the ratio of total yearly rainfall to yearly mean Land Surface Temperature) based on the accumulated monthly precipitation and the monthly Land Surface Temperature in growing season for the period 2000-2009. The results indicated it is possible to work out an aridity index map with more detailed spatial patterns, which is valuable for identifying human impacts by associated with vegetation and soil moisture characters.

  7. Catastrophic shifts in ecosystems

    Science.gov (United States)

    Scheffer, Marten; Carpenter, Steve; Foley, Jonathan A.; Folke, Carl; Walker, Brian

    2001-10-01

    All ecosystems are exposed to gradual changes in climate, nutrient loading, habitat fragmentation or biotic exploitation. Nature is usually assumed to respond to gradual change in a smooth way. However, studies on lakes, coral reefs, oceans, forests and arid lands have shown that smooth change can be interrupted by sudden drastic switches to a contrasting state. Although diverse events can trigger such shifts, recent studies show that a loss of resilience usually paves the way for a switch to an alternative state. This suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.

  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. Humans in changing shrubland ecosystems

    Science.gov (United States)

    Rosemary L. Pendleton; Stanley G. Kitchen; Andres F. Cibils

    2014-01-01

    Emerging arid-land research and management approaches are increasingly shaped by the recognition of the fact that humans are an integral part of ecosystems. The thrust to study the coupled natural-human dynamics of such systems1 and the growing awareness of the social-ecological nature of rangeland ecosystems2 are prompting a shift in the way we think about current and...

  10. Defining an economics research program to describe and evaluate ecosystem services.

    Science.gov (United States)

    Jeffrey D. Kline

    2007-01-01

    Balancing society’s multiple and sometimes competing objectives regarding forests calls for information describing the direct and indirect benefits resulting from forest policy and management, whether to address wildfire, loss of open space, unmanaged recreation, ecosystem restoration, or other objectives. The USDA Forest Service recently has proposed the concept of...

  11. Deserts and Arid Lands

    Science.gov (United States)

    Brown, Glen F.

    The exponential growth of global population and often concomitant degradation of the environment has forced human expansion into the more hostile and less well-known terrains of arid lands and deserts. Drought in the African Sahel, with recent wholesale movement of tribes seeking survival, has focused interest in such regions. However, geologic and geomorphic knowledge of deserts has expanded slowly until the last few decades. For instance, the arid cycle of erosion, as conceived by William Morse Davis (now deceased; formerly, Harvard University, Cambridge, Mass.), with modifications by W. Penck (now deceased; formerly, Leipzig University, Leipzig, German Democratic Republic), and L. C. King (University of Natal and Durban, South Africa), has dominated desert geomorphological deductions until recently. Since World War II and the verification of plate tectonics, the knowledge of arid lands has increased dramatically, especially in synoptic mapping from remote sensing data and space photography, which transcends political boundaries, thanks to the open skies policy of the U.S. space pioneers.

  12. Assessing the feasibility of integrating ecosystem-based with engineered water resource governance and management for water security in semi-arid landscapes: A case study in the Banas catchment, Rajasthan, India.

    Science.gov (United States)

    Everard, Mark; Sharma, Om Prakash; Vishwakarma, Vinod Kumar; Khandal, Dharmendra; Sahu, Yogesh K; Bhatnagar, Rahul; Singh, Jitendra K; Kumar, Ritesh; Nawab, Asghar; Kumar, Amit; Kumar, Vivek; Kashyap, Anil; Pandey, Deep Narayan; Pinder, Adrian C

    2018-01-15

    Much of the developing world and areas of the developed world suffer water vulnerability. Engineering solutions enable technically efficient extraction and diversion of water towards areas of demand but, without rebalancing resource regeneration, can generate multiple adverse ecological and human consequences. The Banas River, Rajasthan (India), has been extensively developed for water diversion, particularly from the Bisalpur Dam from which water is appropriated by powerful urban constituencies dispossessing local people. Coincidentally, abandonment of traditional management, including groundwater recharge practices, is leading to increasingly receding and contaminated groundwater. This creates linked vulnerabilities for rural communities, irrigation schemes, urban users, dependent ecosystems and the multiple ecosystem services that they provide, compounded by climate change and population growth. This paper addresses vulnerabilities created by fragmented policy measures between rural development, urban and irrigation water supply and downstream consequences for people and wildlife. Perpetuating narrowly technocentric approaches to resource exploitation is likely only to compound emerging problems. Alternatively, restoration or innovation of groundwater recharge practices, particularly in the upper catchment, can represent a proven, ecosystem-based approach to resource regeneration with linked beneficial socio-ecological benefits. Hybridising an ecosystem-based approach with engineered methods can simultaneously increase the security of rural livelihoods, piped urban and irrigation supplies, and the vitality of river ecosystems and their services to beneficiaries. A renewed policy focus on local-scale water recharge practices balancing water extraction technologies is consistent with emerging Rajasthani policies, particularly Jal Swavlamban Abhiyan ('water self-reliance mission'). Policy reform emphasising recharge can contribute to water security and yield socio

  13. Damage caused to the environment by reforestation policies in arid and semi-arid areas of China.

    Science.gov (United States)

    Cao, Shixiong; Tian, Tao; Chen, Li; Dong, Xiaobin; Yu, Xinxiao; Wang, Guosheng

    2010-06-01

    Traditional approaches to ecosystem restoration have considered afforestation to be an important tool. To alleviate land degradation in China, the Chinese government has therefore invested huge amounts of money in planting trees. However, the results of more than half a century of large-scale afforestation in arid and semi-arid China have shown that when the trees are not adapted to the local environment, the policy does not improve the environment, and may instead increase environmental degradation. When precipitation is lower than potential evaporation, surface soil moisture typically cannot sustain forest vegetation, and shrubs or steppe species replace the forest to form a sustainable natural ecosystem that exists in a stable equilibrium with the available water supply. The climate of much of northwestern China appears to be unsuitable for afforestation owing to the extremely low rainfall. Although some small-scale or short-term afforestation efforts have succeeded in this region, many of the resulting forests have died or degraded over longer periods, so policymakers must understand that these small-scale or short-term results do not support an inflexible policy of large-scale afforestation throughout arid and semi-arid northwestern China. Rather than focusing solely on afforestation, it would be more effective to attempt to recreate natural ecosystems that are better adapted to local environments and that thus provide a better chance of sustainable, long-term rehabilitation.

  14. Functional traits drive the contribution of solar radiation to leaf litter decomposition among multiple arid-zone species

    NARCIS (Netherlands)

    Pan, Xu; Song, Yao-Bin; Liu, Guo-Fang; Hu, Yu-Kun; Ye, Xue-Hua; Cornwell, W.K.; Prinzing, A.; Dong, Ming; Cornelissen, J.H.C.

    2015-01-01

    In arid zones, strong solar radiation has important consequences for ecosystem processes. To better understand carbon and nutrient dynamics, it is important to know the contribution of solar radiation to leaf litter decomposition of different arid-zone species. Here we investigated: (1) whether such

  15. Rainwater harvesting in arid and semi-arid zones

    NARCIS (Netherlands)

    Boers, T.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

  16. 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

  17. Sevilleta Long-Term Ecological Research Program: Measuring ecosystem reponses to environmental change

    Science.gov (United States)

    Robert R. Parmenter

    1999-01-01

    The purpose of this paper is to describe the research program of the Sevilleta Long-Term Ecological Research Program (LTER) at the University of New Mexico. Details and data for each of the research topics described can be found in the Sevilleta LTER Internet Homepage (http://sev.lternet.edu/).

  18. Decoupling of soil nutrient cycles as a function of aridity in global drylands

    OpenAIRE

    Delgado Baquerizo, Manuel; Maestre, Fernando T.; Gallardo, Antonio; Bowker, Mathew A.; Matthew D Wallenstein; Quero, Jose L.; Ochoa, Victoria; Gozalo, Beatriz; García Gómez, Miguel; Soliveres, Santiago; García Palacios, Pablo; Berdugo, Miguel; Valencia, Enrique; Escolar, Cristina; Arredondo, Tulio

    2013-01-01

    The biogeochemical cycles of carbon (C), nitrogen (N) and phosphorus (P) are interlinked by primary production, respiration and decomposition in terrestrial ecosystems. It has been suggested that the C, N and P cycles could become uncoupled under rapid climate change because of the different degrees of control exerted on the supply of these elements by biological and geochemical processes. Climatic controls on biogeochemical cycles are particularly relevant in arid, semi-arid and dry sub-humi...

  19. Applying linear programming to estimate fluxes in ecosystems or food webs: An example from the herpetological assemblage of the freshwater Everglades

    Science.gov (United States)

    Diffendorfer, James E.; Richards, Paul M.; Dalrymple, George H.; DeAngelis, Donald L.

    2001-01-01

    We present the application of Linear Programming for estimating biomass fluxes in ecosystem and food web models. We use the herpetological assemblage of the Everglades as an example. We developed food web structures for three common Everglades freshwater habitat types: marsh, prairie, and upland. We obtained a first estimate of the fluxes using field data, literature estimates, and professional judgment. Linear programming was used to obtain a consistent and better estimate of the set of fluxes, while maintaining mass balance and minimizing deviations from point estimates. The results support the view that the Everglades is a spatially heterogeneous system, with changing patterns of energy flux, species composition, and biomasses across the habitat types. We show that a food web/ecosystem perspective, combined with Linear Programming, is a robust method for describing food webs and ecosystems that requires minimal data, produces useful post-solution analyses, and generates hypotheses regarding the structure of energy flow in the system.

  20. Partner-built ecosystem science - The National Ocean Partnership Program as a builder of EBM Tools and Data

    Science.gov (United States)

    Hoffman, P. L.; Green, R. E.; Kohanowich, K. M.

    2016-12-01

    The National Ocean Partnership Program (NOPP) was created in 1997 by federal public law to identify "and carry out partnerships among federal agencies, academia, industry, and other members of the oceanographic scientific community in the areas of data, resources, education, and communications." Since that time, numerous federal agencies have pooled talent, funding, and scientific resources (e.g. ships, aircraft, remote sensors and computing capability) to address pressing ocean science needs which no one entity can manage alone. In this presentation, we will address the ways the National Ocean Policy identifies ecosystem-based management (EBM) as a foundation for providing sound science-based and adaptable management to maintain the health, productivity, and resilience of U.S. ocean, coastal, and Great Lakes ecosystems. Because EBM is an important approach for efficient and effective interagency, multi-jurisdictional, and cross-sectoral marine planning and management, ocean science partnerships such as those provided by NOPP create a pool of regionally-pertinent, nationally-available data from which EBM decision makers can draw to address critical management issues. Specifically, we will provide examples drawn from the last five years of funding to illustrate how the NOPP process works, how it is managed by a federal Interagency Working Group (IWG-OP), and how EBM practitioners can both partner with others through the NOPP and offer guidance on the implementation of projects beneficial to the regional needs of the EBM community. Projects to be discussed have been carried out under the following themes: Arctic Cumulative Impacts: Marine Arctic Ecosystem Study (MARES) - Ecosystem Dynamics and Monitoring of the Beaufort Sea: An Integrated Science Approach. Biodiversity Indicators: Demonstration of a U.S. Marine Biodiversity Observation Network (Marine BON) Long-Term Observations: Coordinated Regional Efforts That Further the U.S. Integrated Ocean Observing System

  1. Millennium Ecosystem Assessment: MA Ecosystems

    Data.gov (United States)

    National Aeronautics and Space Administration — The Millennium Ecosystem Assessment: MA Ecosystems provides data and information on the extent and classification of ecosystems circa 2000, including coastal,...

  2. Payments for Ecosystem Services

    DEFF Research Database (Denmark)

    Chan, Kai M.A; Anderson, Emily K.; Chapman, Mollie

    2017-01-01

    Payments for ecosystem services (PES) programs are one prominent strategy to address economic externalities of resource extraction and commodity production, improving both social and ecological outcomes. But do PES and related incentive programs achieve that lofty goal? Along with considerable...

  3. Assessing the effects of USDA conservation programs on ecosystem services provided by wetlands

    Science.gov (United States)

    The Conservation Effects Assessment Project (CEAP) is led by the U.S. Department of Agriculture (USDA) in an effort to quantify the environmental effects of conservation programs and practices on privately owned agricultural landscapes across the United States. CEAP’s approach includes application ...

  4. 'SINAMI': a tool for the economic evaluation of forest fire management programs in Mediterranean ecosystems

    Science.gov (United States)

    Francisco Rodriguez y Silva; Armando Gonzalez-Caban

    2010-01-01

    Historically, in Spain and most European countries, forest fire budgets have never been subjected to an objective and rigorous economic analysis indicative of the returns on investments in fire management protection programs. Thus far we have witnessed expansive growth of costs without any investment planning. New economic realities and more focussed oversight by...

  5. Optimizing Irrigation Water Allocation under Multiple Sources of Uncertainty in an Arid River Basin

    Science.gov (United States)

    Wei, Y.; Tang, D.; Gao, H.; Ding, Y.

    2015-12-01

    Population growth and climate change add additional pressures affecting water resources management strategies for meeting demands from different economic sectors. It is especially challenging in arid regions where fresh water is limited. For instance, in the Tailanhe River Basin (Xinjiang, China), a compromise must be made between water suppliers and users during drought years. This study presents a multi-objective irrigation water allocation model to cope with water scarcity in arid river basins. To deal with the uncertainties from multiple sources in the water allocation system (e.g., variations of available water amount, crop yield, crop prices, and water price), the model employs a interval linear programming approach. The multi-objective optimization model developed from this study is characterized by integrating eco-system service theory into water-saving measures. For evaluation purposes, the model is used to construct an optimal allocation system for irrigation areas fed by the Tailan River (Xinjiang Province, China). The objective functions to be optimized are formulated based on these irrigation areas' economic, social, and ecological benefits. The optimal irrigation water allocation plans are made under different hydroclimate conditions (wet year, normal year, and dry year), with multiple sources of uncertainty represented. The modeling tool and results are valuable for advising decision making by the local water authority—and the agricultural community—especially on measures for coping with water scarcity (by incorporating uncertain factors associated with crop production planning).

  6. The National Heart, Lung, and Blood Institute Small Business Program: A Comprehensive Ecosystem for Biomedical Product Development.

    Science.gov (United States)

    Marek, Kurt W

    2016-12-01

    Small companies working to develop products in the cardiovascular space face numerous challenges, from regulatory, intellectual property, and reimbursement barriers to securing funds to keep the lights on and reach the next development milestone. Most small companies that spin out from universities have the scientific knowledge, but product development expertise and business acumen are also needed to be successful. Other challenges include reduced interest in early stage technologies (Pharma & Biotech 2015 in Review, EP Vantage) and limited deal flow for cardiovascular products (Gormley B., Wall Street Journal, September 15, 2014). The NHLBI small business program is a comprehensive ecosystem designed to address these critical challenges and to provide resources and expertise to assist early stage companies developing cardiovascular and other products within the institute's mission. This article describes steps that NHLBI has taken to enhance our small business program to more effectively translate basic discoveries into commercial products to benefit patients and public health, including enhancing internal expertise and developing non-financial resources to assist small businesses as they develop their products and seek private sector investment and partnership.

  7. Variaciones en el patrón espacial a pequeña escala de los componentes de la costra biológica en un ecosistema mediterráneo semiárido Small-scale spatial patterns of biological crusts in a Mediterranean semi-arid ecosystem

    Directory of Open Access Journals (Sweden)

    FERNANDO T MAESTRE

    2003-03-01

    Full Text Available RESUMEN La costra biológica constituye una de las propiedades edáficas más importantes en los ecosistemas semiáridos, donde juegan un importante rol en su funcionamiento y dinámica. En los últimos años se ha producido un notable aumento en el conocimiento de la ecofisiología, dinámica y taxonomía de los constituyentes de este tipo de costras, pero pocos estudios hasta la fecha han evaluado los cambios que la vegetación introduce en su patrón espacial a pequeña escala. Con el objetivo de avanzar en el conocimiento sobre las interacciones entre los componentes de la costra biológica y las plantas vasculares, en este artículo se evalúan los efectos del microambiente proporcionado por Stipa tenacissima L. en la distribución espacial de los líquenes foliáceos y los musgos, en estepas semiáridas del SE de España. El principal objetivo de estudio es determinar si el microambiente proporcionado por S. tenacissima promueve la aparición de cambios en el patrón individual de estos componentes de la costra biológica por separado y en su covariación espacial. Para alcanzar este objetivo se ha utilizado el análisis espacial mediante índices de distancia ("spatial analysis by distance indices", SADIE, mediante el cual se detectó un patrón de distribución agregado en los líquenes foliáceos y los musgos, pero el microambiente proporcionado por S. tenacissima sólo introdujo cambios significativos en el patrón espacial de los primeros. No se encontró un efecto significativo del microambiente proporcionado por S. tenacissima en la covariación espacial entre los líquenes foliáceos y los musgos. Los resultados obtenidos muestran cómo S. tenacissima es capaz de modificar la distribución espacial a pequeña escala de los componentes de la costra biológica y sugieren la facilitación entre esta especie y los líquenes foliáceos.Biological crusts are a common feature of soil surface in arid and semiarid ecosystems, where they

  8. Incubation Programs from Public Research Organizations as Catalysts for Open Business Ecosystems

    Directory of Open Access Journals (Sweden)

    Sven H. De Cleyn

    2013-04-01

    Full Text Available In many economies, new knowledge and technology creation and transfer towards local entities and new startups have been recognized as catalysts for industry renewal and tools for safeguarding (or even enhancing a region’s employment and prosperity. This article presents a case study of iMinds, a network organization in Flanders, Belgium. The organization fosters interdisciplinary research in information and communication technologies (ICT and strongly engages in transferring these new technologies towards local actors and in creating and supporting new startups. iMinds’ incubation and entrepreneurship programs act as catalysts for open innovation and company startup activities in the Flemish region.

  9. Estimating annual rainfall threshold for establishment of tree species in water-limited ecosystems using tree-ring data

    NARCIS (Netherlands)

    Lopez, B.C.; Holmgren, M.; Sabate, S.; Gracia, C.A.

    2008-01-01

    In arid and semi-arid ecosystems, water availability is discontinuous, highly variable, and characterized by discrete pulse events separated by long periods of limited resource availability. Plant recruitment in these ecosystems is also episodic and dependent on the water available during and after

  10. 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.

  11. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Togtohyn Chuluun; Dennis Ojima [Colorado State University, Fort Collins, CO (USA). Natural Resource Ecology Laboratory

    2002-07-01

    Dramatic changes in land use have occurred in arid and semi-arid lands of 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 in China 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.

  13. Climate change impacts on freshwater wetland hydrology and vegetation cover cycling along a regional aridity gradient

    Science.gov (United States)

    Global mean temperature may increase up to 6°C by the end of this century and together with precipitation change may steepen regional aridity gradients, impacting the hydrology, productivity, diversity, and ecosystem goods and services from freshwater wetlands, where the water balance is tightly cou...

  14. Understanding the science of climate change: Talking Points - Impacts to arid lands

    Science.gov (United States)

    Rachel Loehman

    2010-01-01

    Arid ecosystems are particularly sensitive to climate change and climate variability because organisms in these regions live near their physiological limits for water and temperature stress. Slight changes in temperature or precipitation regimes, or in magnitude and frequency of extreme climatic events, can significantly alter the composition, abundance, and...

  15. Arid soil microbial enzymatic activity profile as affected by geographical location and soil degradation status

    Science.gov (United States)

    Evaluating soil health is critical for any successful remediation effort. Arid lands, with their minimal carbon and water contents, low nutritional status and restricted, seasonal microbial activity pose specific challenges to soil health restoration and by extension, restoration of ecosystem repr...

  16. Evaluating impacts of recharging partially treated wastewater on groundwater aquifer in semi-arid region by integration of monitoring program and GIS technique.

    Science.gov (United States)

    Alslaibi, Tamer M; Kishawi, Yasser; Abunada, Ziyad

    2017-05-01

    The current study investigates the impact of recharging of partially treated wastewater through an infiltration basin on the groundwater aquifer quality parameters. A monitoring program supported by a geographic information analysis (GIS) tool was used to conduct this study. Groundwater samples from the entire surrounding boreholes located downstream the infiltration basin, in addition to samples from the recharged wastewater coming from the Beit Lahia wastewater treatment (BLWWTP), were monitored and analysed between 2011 and 2014. The analysis was then compared with the available historical data since 2008. Results revealed a groundwater replenishment with the groundwater level increased by 1.0-2.0 m during the study period. It also showed a slight improvement in the groundwater quality parameters, mainly a decrease in TDS, Cl(-) and NO3(-) levels by 5.5, 17.1 and 20%, respectively, resulting from the relatively better quality of the recharged wastewater. Nevertheless, the level of boron and ammonium in the groundwater wells showed a significant increase over time by 96 and 100%, respectively. Moreover, the infiltration rate was slowed down in time due to the relatively high level of total suspended solid (TSS) in the infiltrated wastewater.

  17. Ecosystem services

    Science.gov (United States)

    Trista Patterson

    2014-01-01

    Since its inception, the ecosystem service approach has stimulated interest from numerous planning, management, and partnership perspectives. To date, however, research that quantifies ecosystem services in the study area (in the form of explicit ecosystem service studies) has been limited. This chapter reviews and synthesizes the concept of ecosystem services,...

  18. Flower diversity and bee reproduction in an arid ecosystem

    Directory of Open Access Journals (Sweden)

    Jimena Dorado

    2016-07-01

    Full Text Available Background: Diverse flower communities are more stable in floral resource production along the flowering season, but the question about how the diversity and stability of resources affect pollinator reproduction remains open. High plant diversity could favor short foraging trips, which in turn would enhance bee fitness. In addition to plant diversity, greater temporal stability of floral resources in diverse communities could favor pollinator fitness because such communities are likely to occupy the phenological space more broadly, increasing floral availability for pollinators throughout the season. In addition, this potential effect of flower diversity on bee reproduction could be stronger for generalist pollinators because they can use a broader floral spectrum. Based on above arguments we predicted that pollinator reproduction would be positively correlated to flower diversity, and to temporal stability in flower production, and that this relationship would be stronger for the most generalized pollinator species. Materials and Methods: Using structural equation models, we evaluated the effect of these variables and other ecological factors on three estimates of bee reproduction (average number of brood cells per nest per site, total number of brood cells per site, and total number of nests per site, and whether such effects were modulated by bee generalization on floral resources. Results: Contrary to our expectations, flower diversity had no effect on bee reproduction, stability in flower production had a weakly negative effect on one of the bee reproductive variables, and the strength of the fitness-diversity relationship was unrelated to bee generalization. In contrast, elevation had a negative effect on bee reproduction, despite the narrow elevation range encompassed by our sites. Discussion: Flower diversity did not affect the reproduction of the solitary bees studied here. This result could stem from the context dependence of the diversity-stability relationship, given that elevation had a positive effect on flower diversity but a negative effect on bee reproduction. Although high temporal stability in flower production is expected to enhance pollinator reproduction, in our study it had a weakly negative—instead of positive—effect on the average number of brood cells per nest. Other environmental factors that vary with elevation could influence bee reproduction. Our study focused on a small group of closely-related bee species, which cautions against generalization of our findings to other groups of pollinators. More studies are clearly needed to assess the extent to which pollinator demography is influenced by the diversity of floral resources.

  19. The Effect of Payments for Ecosystem Services Programs on the Relationship of Livelihood Capital and Livelihood Strategy among Rural Communities in Northwestern China

    Directory of Open Access Journals (Sweden)

    Fei Wang

    2015-07-01

    Full Text Available The security and quality of livelihoods for peasant households is the core issue for rural areas in China. A stable livelihood contributes to the harmonious development of related polices, poverty eradication and sustainable use of resources. In Qinghe County, located in the extremely arid zone of Northwest China, 238 validated surveys were conducted. The analysis focuses on the importance of livelihood capitals for the selection of on- or off-farm livelihood strategies among beneficiaries of different kinds of ecological compensation packages. The goal is to see if different groups of beneficiaries are better able to pursue off-farm livelihoods activity, which reduces pressure on the resource base, and whether specific capitals are especially effective in helping households pursue off-farm livelihoods, which benefits their well-being. The findings show that proportionally more herdsmen (who participated in a pastureland rehabilitation program were able to pursue off-farm livelihoods than farmers (who participated in the cultivated land reforestation program, and especially agro-pastoralists (who participated in both programs. Further, models of livelihood strategy show that human and financial capitals facilitate off-farm livelihoods, while productive capital tends to lead to on-farm livelihoods. These findings indicate that there is no single determinant of livelihood strategy, and future policies must consciously differentiate among beneficiaries to reach the desired result.

  20. Quantitative assessments of water-use efficiency in Temperate Eurasian Steppe along an aridity gradient.

    Science.gov (United States)

    Chen, Yizhao; Li, Jianlong; Ju, Weimin; Ruan, Honghua; Qin, Zhihao; Huang, Yiye; Jeelani, Nasreen; Padarian, José; Propastin, Pavel

    2017-01-01

    Water-use efficiency (WUE), defined as the ratio of net primary productivity (NPP) to evapotranspiration (ET), is an important indicator to represent the trade-off pattern between vegetation productivity and water consumption. Its dynamics under climate change are important to ecohydrology and ecosystem management, especially in the drylands. In this study, we modified and used a late version of Boreal Ecosystem Productivity Simulator (BEPS), to quantify the WUE in the typical dryland ecosystems, Temperate Eurasian Steppe (TES). The Aridity Index (AI) was used to specify the terrestrial water availability condition. The regional results showed that during the period of 1999-2008, the WUE has a clear decreasing trend in the spatial distribution from arid to humid areas. The highest annual average WUE was in dry and semi-humid sub-region (DSH) with 0.88 gC mm-1 and the lowest was in arid sub-region (AR) with 0.22 gC mm-1. A two-stage pattern of WUE was found in TES. That is, WUE would enhance with lower aridity stress, but decline under the humid environment. Over 65% of the region exhibited increasing WUE. This enhancement, however, could not indicate that the grasslands were getting better because the NPP even slightly decreased. It was mainly attributed to the reduction of ET over 70% of the region, which is closely related to the rainfall decrease. The results also suggested a similar negative spatial correlation between the WUE and the mean annual precipitation (MAP) at the driest and the most humid ends. This regional pattern reflected the different roles of water in regulating the terrestrial ecosystems under different aridity levels. This study could facilitate the understanding of the interactions between terrestrial carbon and water cycles, and thus contribute to a sustainable management of nature resources in the dryland ecosystems.

  1. Quantitative assessments of water-use efficiency in Temperate Eurasian Steppe along an aridity gradient.

    Directory of Open Access Journals (Sweden)

    Yizhao Chen

    Full Text Available Water-use efficiency (WUE, defined as the ratio of net primary productivity (NPP to evapotranspiration (ET, is an important indicator to represent the trade-off pattern between vegetation productivity and water consumption. Its dynamics under climate change are important to ecohydrology and ecosystem management, especially in the drylands. In this study, we modified and used a late version of Boreal Ecosystem Productivity Simulator (BEPS, to quantify the WUE in the typical dryland ecosystems, Temperate Eurasian Steppe (TES. The Aridity Index (AI was used to specify the terrestrial water availability condition. The regional results showed that during the period of 1999-2008, the WUE has a clear decreasing trend in the spatial distribution from arid to humid areas. The highest annual average WUE was in dry and semi-humid sub-region (DSH with 0.88 gC mm-1 and the lowest was in arid sub-region (AR with 0.22 gC mm-1. A two-stage pattern of WUE was found in TES. That is, WUE would enhance with lower aridity stress, but decline under the humid environment. Over 65% of the region exhibited increasing WUE. This enhancement, however, could not indicate that the grasslands were getting better because the NPP even slightly decreased. It was mainly attributed to the reduction of ET over 70% of the region, which is closely related to the rainfall decrease. The results also suggested a similar negative spatial correlation between the WUE and the mean annual precipitation (MAP at the driest and the most humid ends. This regional pattern reflected the different roles of water in regulating the terrestrial ecosystems under different aridity levels. This study could facilitate the understanding of the interactions between terrestrial carbon and water cycles, and thus contribute to a sustainable management of nature resources in the dryland ecosystems.

  2. Hydrologic Connectivity: a Framework to Understand Threshold Behaviour in Semi-Arid Landscapes.

    Science.gov (United States)

    Saco, Patricia; Rodriguez, Jose; Keesstra, Saskia; Moreno-de las Heras, Mariano; Sandi, Steven; Baartman, Jantiene; Cerdà, Artemi

    2017-04-01

    Anthropogenic activities and climate change are imposing an unprecedented pressure on arid and semi-arid ecosystems, where shortage of water can trigger shifts in landscapes' structures and function leading to degradation and desertification. Hydrological connectivity is a useful framework for understanding water redistribution and scaling issues associated to runoff and sediment production, since human and/or natural disturbances alter the surface water availability and pathways increasing/decreasing connectivity. In this presentation, we illustrate the use of the connectivity framework for several examples of dryland systems that are analysed at a variety of spatial and temporal scales. In doing so, we draw particular attention to the analysis of co-evolution of system structures and function, and how they drive threshold behaviour leading to desertification and degradation. We first analyse the case of semi-arid rangelands, where feedbacks between decline in vegetation density and landscape erosion reinforces degradation processes driven by changes in connectivity until a threshold is crossed above which the return to a functional system is unlikely. We then focus on semi-arid wetlands, where decreases in water volumes promotes dryland vegetation encroachment that changes drainage conditions and connectivity potentially reinforcing redistribution of flow paths to other wetland areas. The examples presented highlight the need to incorporate a co-evolutionary framework for the analysis of changing connectivity patterns and the emergence of thresholds in arid and semi-arid systems.

  3. 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.

  4. Analysis and evaluation of tillage on an alfisol in a 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

  5. Mathematical Modeling for Evaluation of Field Water Supply Alternatives (Arid and Semi-Arid Regions).

    Science.gov (United States)

    1981-01-01

    EVALUATION OF FIELD WATER SUPPLY ALTERNATIVES ( Arid and Semi - Arid Regions) FINAL REPORT eJ. M. Morgan, Jr. J. R. Sculley LV. J. Ciccone* aD. K. Jamison J. W...Final Report Water Supply Alternatives 1 August 79-31 January 81 ( Arid and Semi - Arid Regions) 6. PERFORMING ORG. REPORT NUMBER AUTHOR(S) S. CONTRACT...CLAUIFICATION OF THIS PAGE(Whan Data Entesed) 20. (Cont’d.) ~issues pertinent to the production of water in an arid or semi - arid environment, and, finally

  6. A mesic maximum in biological water use demarcates biome sensitivity to aridity shifts.

    Science.gov (United States)

    Good, Stephen P; Moore, Georgianne W; Miralles, Diego G

    2017-12-01

    Biome function is largely governed by how efficiently available resources can be used and yet for water, the ratio of direct biological resource use (transpiration, E T) to total supply (annual precipitation, P) at ecosystem scales remains poorly characterized. Here, we synthesize field, remote sensing and ecohydrological modelling estimates to show that the biological water use fraction (E T/P) reaches a maximum under mesic conditions; that is, when evaporative demand (potential evapotranspiration, E P) slightly exceeds supplied precipitation. We estimate that this mesic maximum in E T/P occurs at an aridity index (defined as E P/P) between 1.3 and 1.9. The observed global average aridity of 1.8 falls within this range, suggesting that the biosphere is, on average, configured to transpire the largest possible fraction of global precipitation for the current climate. A unimodal E T/P distribution indicates that both dry regions subjected to increasing aridity and humid regions subjected to decreasing aridity will suffer declines in the fraction of precipitation that plants transpire for growth and metabolism. Given the uncertainties in the prediction of future biogeography, this framework provides a clear and concise determination of ecosystems' sensitivity to climatic shifts, as well as expected patterns in the amount of precipitation that ecosystems can effectively use.

  7. Inside Ecosystems.

    Science.gov (United States)

    Moll, Gary; And Others

    1995-01-01

    The third in a series of articles featuring the urban ecosystem. Discusses the inner workings of an ecosystem and the links that connect its elements, including the link between people and the environment. Graphics illustrate "layers" of the landscape. (LZ)

  8. Alpine ecosystems

    Science.gov (United States)

    P.W. Rundel; C.I. Millar

    2016-01-01

    Alpine ecosystems are typically defined as those areas occurring above treeline, while recognizing that alpine ecosystems at a local scale may be found below this boundary for reasons including geology, geomorphology, and microclimate. The lower limit of the alpine ecosystems, the climatic treeline, varies with latitude across California, ranging from about 3500 m in...

  9. Effects of Aridity and Vegetation on Plant-wax δD in Modern Lake Sediments

    Science.gov (United States)

    Polissar, P. J.; Freeman, K. H.

    2010-12-01

    Plant waxes are preserved over geologic timescales, and are found in diverse ancient sediments and soils. Observations that these molecules have hydrogen isotopic signatures that can be systematically related to that of modern precipitation have fueled aspirations to reconstruct ancient precipitation δD values. However, molecular isotopic signatures also reflect climate and plant physiological factors, and until better understood, these limit our ability to quantitatively interpret sedimentary lipid records. To advance our understanding of the influence of both ecosystem flora and climate (especially aridity) at the field scale, we analyzed the deuterium content of plant-waxes from sediments in 28 modern lakes located in watersheds which receive precipitation with a wide range of δD values, and are characterized by distinct vegetation types and regional climates. We found that the apparent isotopic fractionation (ɛa) between plant-wax n-alkanes and precipitation differs with watershed ecosystem type and structure, and decreases with increasing regional aridity as measured by enrichment of 2H and 18O associated with evaporation of lake waters. The most negative ɛa values represent signatures least affected by aridity; these values were: -125 ± 5 ‰ for tropical evergreen and dry forests, -130 ‰ for a temperate broadleaf forest, -120 ± 9 ‰ for the high-altitude tropical páramo (herbs, shrubs and grasses), and -98 ± 6 ‰ for North American montane gymnosperm forests. Minimum ɛa values reflect ecosystem-dependent differences in leaf water enrichment and soil evaporation. Slopes of lipid/lakewater isotopic enrichments differ slightly with ecosystem structure (i.e. open shrublands vs. forests) and overall are quite small (slopes = 0 to 2), indicating low sensitivity of lipid δD variations to aridity compared with coexisting lake waters. This finding provides an approach for reconstructing ancient precipitation signatures based on plant-wax

  10. 50 years of water extraction in the Pampa del Tamarugal basin: Can Prosopis tamarugo trees survive in the hyper-arid Atacama Desert (Northern Chile)?

    NARCIS (Netherlands)

    Chávez Oyanadel, R.O.; Clevers, J.G.P.W.; Decuyper, M.; Bruin, de S.; Herold, M.

    2016-01-01

    Groundwater-dependent ecosystems are threatened worldwide by unsustainable groundwater (GW) extraction. This is the case of the Prosopis tamarugo Phil forest in the hyper-arid Atacama Desert (Northern Chile), one of the most extreme ecosystems on Earth. Despite concerns about the conservation of

  11. Rural Household Preferences for Active Participation in “Payment for Ecosystem Service” Programs: A Case in the Miyun Reservoir Catchment, China

    Science.gov (United States)

    Jiang, Xuemei; Zhang, Kebin; Yang, Xiaohui

    2017-01-01

    Many payment for ecosystem services (PES) programs, such as the Slope Land Conversion Program (SLCP), are passive and require full participation by impacted households. In contrast, this study considers the alternative of “active and incomplete” participation in PES programs, in which participants are not obliged to contract their own land, and have the right to select into the program or not. This type of program has been popular over the last decade in China; however, there have been few studies on the characteristics of willingness to participate and implementation. As such, this paper uses the Choice Experiment (CE) method to explore ways for inducing effective program participation, by analyzing the effects of different regime attributes. The case study used to analyze participation utility was the Jing-Ji Afforestation Program for Ecological and Water Protection (JAPEWP), a typical active-participation forestry PES program, and a key source of water near Beijing in the Miyun Reservoir Catchment (MRC). Analyzing rural household survey data indicated that the program faces a variety of challenges, including long-term maintenance, implementation performance, cost-effectiveness, and monitoring approaches. There are also challenges with one-size-fits-all payment strategies, due to ineffective program participation or imperfect implementation regimes. In response, this study proposes several policies, including providing secure and complete land tenure to the participants, creating more local off-farm employment opportunities, designing performance-based monitoring systems that are integrated with financial incentives, applying differentiated payment strategies, providing capacity building to support forestation activities, and establishing a comprehensive implementation regime that would address these challenges. These policy conclusions provide valuable lessons for other active-participation PES programs as well. PMID:28046106

  12. The Soil Program of the Restoration Seedbank Initiative: addressing knowledge gaps in degraded soils for use in dryland restoration

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Bateman, Amber; Erickson, Todd E.; Turner, Shane; Merritt, David J.

    2017-04-01

    Global environmental changes and other anthropogenic impacts are rapidly transforming the structure and functioning of ecosystems worldwide. These changes are leading to land degradation with an estimated 25 % of the global land surface being affected. Landscape-scale restoration of these degraded ecosystems has therefore been recognised globally as an international priority. In the resource-rich biodiverse semi-arid Pilbara region of north-west Western Australia hundreds of thousands of hectares are disturbed due to established and emerging iron-ore mine operations. At this scale, the need to develop cost-effective large-scale solutions to restore these landscapes becomes imperative to preserve biodiversity and achieve functionality and sustainability of these ecosystems. The Restoration Seedbank Initiative (RSB) (http://www.plants.uwa.edu.au/ research/restoration-seedbank-initiative) is a five-year multidisciplinary research project that aims to build knowledge and design strategies to restore mine-impacted landscapes in the Pilbara and other arid and semi-arid landscapes worldwide (Kildiseheva et al., 2016). The RSB comprises four research programs that focus on seedbank management and curation, seed storage, seed enhancement, and the use of alternative soil substrates (soil or growing medium program) respectively. These multi-disciplinary programs address the significant challenges of landscape scale restoration in arid systems. In the soil program we follow an integrated approach that includes the characterization of undisturbed ecosystems, assessment of restored soils with the use of soil quality indicators, and design of alternative soil substrates to support the establishment of native plant communities. A series of glasshouse studies and field trials have been conducted in the last three years to advance our knowledge on soil limitations and to provide solutions to effectively overcome these challenges in arid ecosystem restoration. These studies include

  13. Preliminary evaluation of selected in situ remediation technologies for Volatile Organic Compound contamination at Arid sites

    Energy Technology Data Exchange (ETDEWEB)

    Lenhard, R.J.; Gerber, M.A.; Amonette, J.E.

    1992-10-01

    To support the Volatile Organic Compounds-Arid Site (VOC-Arid) Integrated Demonstration (ID) in its technical, logistical, institutional, and economical testing of emerging environmental management and restoration technologies. Pacific Northwest Laboratory(a) is evaluating several in situ remediation technologies for possible inclusion in the demonstration. The evaluations are made with respect to the initial focus of the VOC-Arid ID: the carbon tetrachloride contamination at the Hanford Site, where it was disposed to the vadose zone along with other volatile and nonvolatile organic wastes. heavy metals, acids. and radionuclides. The purposes of this report are (1) to identify candidate in situ technologies for inclusion in the program, (2) to evaluate the candidate technologies based on their potential applicability to VOC contamination at arid sites and geologic conditions representative of the ID host site (i.e., Hanford Site), and (3) to prioritize those technologies for future US Department of Energy (DOE) support.

  14. Increasing aridity reduces soil microbial diversity and abundance in global drylands

    Science.gov (United States)

    Delgado-Baquerizo, Manuel; Jeffries, Thomas C.; Eldridge, David J.; Ochoa, Victoria; Gozalo, Beatriz; Quero, José Luis; García-Gómez, Miguel; Gallardo, Antonio; Ulrich, Werner; Bowker, Matthew A.; Arredondo, Tulio; Barraza-Zepeda, Claudia; Bran, Donaldo; Florentino, Adriana; Gaitán, Juan; Gutiérrez, Julio R.; Huber-Sannwald, Elisabeth; Jankju, Mohammad; Mau, Rebecca L.; Miriti, Maria; Naseri, Kamal; Ospina, Abelardo; Stavi, Ilan; Wang, Deli; Woods, Natasha N.; Yuan, Xia; Zaady, Eli; Singh, Brajesh K.

    2015-01-01

    Soil bacteria and fungi play key roles in the functioning of terrestrial ecosystems, yet our understanding of their responses to climate change lags significantly behind that of other organisms. This gap in our understanding is particularly true for drylands, which occupy ∼41% of Earth´s surface, because no global, systematic assessments of the joint diversity of soil bacteria and fungi have been conducted in these environments to date. Here we present results from a study conducted across 80 dryland sites from all continents, except Antarctica, to assess how changes in aridity affect the composition, abundance, and diversity of soil bacteria and fungi. The diversity and abundance of soil bacteria and fungi was reduced as aridity increased. These results were largely driven by the negative impacts of aridity on soil organic carbon content, which positively affected the abundance and diversity of both bacteria and fungi. Aridity promoted shifts in the composition of soil bacteria, with increases in the relative abundance of Chloroflexi and α-Proteobacteria and decreases in Acidobacteria and Verrucomicrobia. Contrary to what has been reported by previous continental and global-scale studies, soil pH was not a major driver of bacterial diversity, and fungal communities were dominated by Ascomycota. Our results fill a critical gap in our understanding of soil microbial communities in terrestrial ecosystems. They suggest that changes in aridity, such as those predicted by climate-change models, may reduce microbial abundance and diversity, a response that will likely impact the provision of key ecosystem services by global drylands. PMID:26647180

  15. Photosynthesis and growth reduction with warming are driven by nonstomatal limitations in a Mediterranean semi?arid shrub

    OpenAIRE

    Leon-Sanchez, Lupe; Nicolás, Emilio; Nortes, Pedro A.; T. Maestre, Fernando; Querejeta, José I.

    2016-01-01

    Abstract 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 ...

  16. The tides and inflows in the mangroves of the Everglades (TIME) interdisciplinary project of the South Florida Ecosystem Program

    Science.gov (United States)

    Schaffranek, R.W.

    2001-01-01

    The U. S. Geological Survey (USGS) has a prominent role in the Federal Government's comprehensive restoration plan for the south Florida ecosystem encompassing the Everglades-the largest remaining subtropical wilderness in the continental United States. USGS scientists, in collaboration with researchers from the National Park Service (NPS), other governmental agencies, and academia, are providing scientific information to land and resource managers for planning, executing, and evaluating restoration actions. One major thrust of the restoration effort is to restore the natural functioning of the ecosystem to predrainage conditions, an objective that requires knowledge of the hydrologic and hydraulic factors that affect the flow of water. A vast network of interlaced canals, rimmed with levees and fitted with hydraulic control structures, and highways, built on elevated embankments lined by borrow ditches and undercut by culverts, now act to control and direct the flow of water through the shallow low-gradient wetlands. As water flows south from Lake Okeechobee past the city of Miami and through Everglades National Park (ENP), it is diminished by canal diversions, augmented by seasonably variable precipitation, and depleted through evapotranspiration. Along its path, the shallow flowing water, referred to as sheet flow, interacts with surficial aquifers and is subject to the resistance effects of variably dense vegetation and forcing effects of winds. New scientific investigations are providing additional insight into the hydrologic and hydraulic processes governing the flow, and recent data-collection efforts are supplying more comprehensive data describing the flow behavior, both of which are benefiting development of improved numerical models to evaluate and restore the natural functioning of the ecosystem.

  17. 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, Paul C.

    2016-01-01

    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.

  18. Coral Reef Ecosystems Monitoring Feature Service

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Coral Reef Ecosystem Monitoring GIS data service provides access to data collected in the Mariana Archipelago by the Coral Reef Ecosystem Program of the Pacific...

  19. Landsat and GRACE observations of arid wetland dynamics in a dryland river system under multi-decadal hydroclimatic extremes

    Science.gov (United States)

    Xie, Zunyi; Huete, Alfredo; Ma, Xuanlong; Restrepo-Coupe, Natalia; Devadas, Rakhesh; Clarke, Kenneth; Lewis, Megan

    2016-12-01

    Arid wetlands are important for biodiversity conservation, but sensitive and vulnerable to climate variability and hydroclimatic events. Amplification of the water cycle, including the increasing frequency and severity of droughts and wet extremes, is expected to alter spatial and temporal hydrological patterns in arid wetlands globally, with potential threats to ecosystem services and their functioning. Despite these pressing challenges, the ecohydrological interactions and resilience of arid wetlands to highly variable water regimes over long time periods remain largely unknown. Recent broad-scale drought and floods over Australia provide unique opportunities to improve our understanding of arid wetland ecosystem responses to hydroclimatic extremes. Here we analysed the ecohydrological dynamics of the Coongie Lakes arid wetland in central Australia, one of the world's largest Ramsar-designated wetlands, using more than two decades (1988-2011) of vegetation and floodwater extent retrievals derived from Landsat satellite observations. To explore the impacts of large-scale hydrological fluctuations on the arid wetland, we further coupled Landsat measurements with Total Water Storage Anomaly (TWSA) data obtained from the Gravity Recovery and Climate Experiment (GRACE) satellites. Pronounced seasonal and inter-annual variabilities of flood and vegetation activities were observed over the wetland, with variations in vegetation growth extent highly correlated with flood extent (r = 0.64, p hydrological dynamics and associated ecosystem responses to be largely driven by the two phases (El Niño and La Niña) of the El Nino-Southern Oscillation (ENSO) ocean-atmosphere system. Changes in flood and vegetation extent were better explained by GRACE-TWSA (r = 0.8, lag = 0 month) than rainfall (r = 0.34, lag = 3 months) over the water source area, demonstrating that TWS is a valuable hydrological indicator for complex dryland river systems. The protracted Millennium Drought

  20. China’s Conversion of Cropland to Forest Program for Household Delivery of Ecosystem Services: How Important is a Local Implementation Regime to Survival Rate Outcomes?

    Directory of Open Access Journals (Sweden)

    Michael T. Bennett

    2014-09-01

    Full Text Available China’s Conversion of Cropland to Forests Program (CCFP is the world’s largest afforestation-based Payments for Ecosystem Services (PES program, having retired and afforested over 24 million ha involving 32 million rural households. Prior research has primarily focused on the CCFP’s rural welfare impacts, with few studies on program-induced environmental improvements, particularly at the household level. In this study, data from a 2010 survey covering 2808 rural households from across China was analyzed using an interval regression model to explain household-reported survival rates of trees planted on program-enrolled cropland. In addition to household-level factors, we explore the influence of local conditions and institutional configurations by exploiting the wide diversity of contexts covered by the data set. We find that households with more available labor and more forestry experience manage trees better, but that higher opportunity costs for both land and labor have the opposite effect. We also find that the local implementation regime- e.g., the degree of prior consultation with participants and regular monitoring - has a strong positive effect on reported survivorship. We suggest that the level of subsidy support to participating households will be key to survivorship of trees in planted CCFP forests for some time to come.

  1. WIRE project- Soil water repellence in biodiverse semi arid environments: new insights and implications for ecological restoration

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Jiménez-Morillo, Nicasio T.; Jordan, Antonio; Zavala, Lorena M.; Stevens, Jason; González-Pérez, Jose Antonio

    2017-04-01

    Background Soil water repellency (SWR) can have a critical effect on the restoration of disturbed ecosystems causing poor plant establishment and promoting erosion processes. Although SWR has been reported in most continents of the world for different soil types, climate conditions and land uses, there are still many research gaps in the knowledge of its causes and controlling factors (Doerr et al.,2000; Jordan et al., 2013), particularly in Mediterranean arid semi arid environments which are largely affected by this phenomenon. The WIRE project aims to investigate SWR in soils under different vegetation types of dominant biodiverse ecosystems of Western Australia (WA), e.g. hummock grasslands and Banksia woodlands, as well as characterizing organic compounds that induce hydrophobicity in these soils. Banksia woodlands (BW) are of particular interest in this project. These are iconic ecosystems of WA composed by an overstorey dominated by Proteaceae that are threatened by sand mining activities and urban expansion. Conservation and restoration of these woodlands are critical but despite considerable efforts to restore these areas, the success of current rehabilitation programs is poor due to the high sensitivity of the ecosystem to drought stress and the disruption of water dynamics in mature BW soils that result in low seedling survival rates (5-30%). The main objectives of this collaborative research are: i) to identify SWR intensity and severity under different vegetation types and evaluate controlling factors in both hummock grasslands and BW (ii) to characterize hydrophobic compounds in soils using analytical pyrolysis techniques and iii) to investigate the impact of SWR on water economy in relation with soil functioning and plant strategies for water uptake in pristine BW. Methods In a series of field trials and experimental studies, we measured SWR of soil samples under lab conditions in oven-dry samples (48 h, 105 °C) that were previously collected under

  2. Plants reverse warming effect on ecosystem water balance

    OpenAIRE

    Zavaleta, Erika S.; Thomas, Brian D.; Chiariello, Nona R.; Asner, Gregory P.; Shaw, M. Rebecca; Christopher B. Field

    2003-01-01

    Models predict that global warming may increase aridity in water-limited ecosystems by accelerating evapotranspiration. We show that interactions between warming and the dominant biota in a grassland ecosystem produced the reverse effect. In a 2-year field experiment, simulated warming increased spring soil moisture by 5–10% under both ambient and elevated CO2. Warming also accelerated the decline of canopy greenness (normalized difference vegetation index) each spring...

  3. Application of a Double-Sided Chance-Constrained Integer Linear Program for Optimization of the Incremental Value of Ecosystem Services in Jilin Province, China

    Directory of Open Access Journals (Sweden)

    Baofeng Cai

    2017-08-01

    Full Text Available The Interconnected River System Network Project (IRSNP is a significant water supply engineering project, which is capable of effectively utilizing flood resources to generate ecological value, by connecting 198 lakes and ponds in western Jilin, northeast China. In this article, an optimization research approach has been proposed to maximize the incremental value of IRSNP ecosystem services. A double-sided chance-constrained integer linear program (DCCILP method has been proposed to support the optimization, which can deal with uncertainties presented as integers or random parameters that appear on both sides of the decision variable at the same time. The optimal scheme indicates that after rational optimization, the total incremental value of ecosystem services from the interconnected river system network project increased 22.25%, providing an increase in benefits of 3.26 × 109 ¥ compared to the original scheme. Most of the functional area is swamp wetland, which provides the greatest ecological benefits. Adjustment services increased obviously, implying that the optimization scheme prioritizes ecological benefits rather than supply and production services.

  4. Special software for aridity indices calculation (AICS; Vojvodina, Serbia case study

    Directory of Open Access Journals (Sweden)

    Hrnjak Ivana

    2013-01-01

    Full Text Available Knowledge of aridity is necessary to explain the characteristics of the geographical landscape. Increasing aridity due to global warming can be a real hazard, with the threat of desertification. The main aim of this paper is to introduce special software for aridity indices calculation (AICS, and on the basis of those data to peruse aridity as a natural hazard. These indices were calculated from data obtained from 10 meteorological stations in the Vojvodina region for the period from 1949 to 2006. In order to calculate the De Martonne aridity index, IDM, and the Pinna combinative index, IP, software was created using C# programming language. Not only that this software shows the values of indices, but also it shows to which class it belongs according to the De Martonne climate classification. Graphical presentation of both calculated indices is also enabled. Further development of AICS is planned. As additional software package here was used ArcMap 10.1 for the spatial representation and visualization of the aridity indices. [Projekat Ministarstva nauke Republike Srbije, br. 176020 i br. 176013

  5. Human impacts on riparian ecosystems of the Middle Rio Grande Valley during historic times

    Science.gov (United States)

    Frank E. Wozniak

    1996-01-01

    The development of irrigation agriculture in historic times has profoundly impacted riparian ecosystems in the Middle Rio Grande Valley of New Mexico. A vital relationship has existed between water resources and settlement in the semi-arid Southwest since prehistoric times. Levels of technology have influenced human generated changes in the riparian ecosystems of the...

  6. Biomonitoring of Environmental Status and Trends (BEST) Program: Selected Methods for Monitoring Chemical Contaminants and their Effects in Aquatic Ecosystems

    National Research Council Canada - National Science Library

    Schmitt, Christopher

    2000-01-01

    This document describes the suite of biological methods of the U.S. Geological Survey Biomonitoring of Environmental Status and Trends program for monitoring chemical contaminants and their effects on fish...

  7. Ecosystem management issues

    Science.gov (United States)

    Jim Boynton

    1995-01-01

    Although recognized as an important tool for ecosystem maintenance, fuels management, and a variety of other purposes, the prescribed fire program in the Pacific Southwest Region of the USDA Forest Service has been constrained by several factors. These range from funding availability, to debates on the effect of fire on the habitat of sensitive species, to competition...

  8. 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.

  9. Ecosystem functioning

    National Research Council Canada - National Science Library

    Jax, Kurt

    2010-01-01

    "In the face of decreasing biodiversity and ongoing global changes, maintaining ecosystem functioning is seen both as a means to preserve biological diversity as well as for safeguarding human well...

  10. Apparent over-investment in leaf venation relaxes leaf morphological constraints on photosynthesis in arid habitats

    Science.gov (United States)

    de Boer, Hugo; Drake, Paul; Veneklaas, Erik

    2017-04-01

    water transport confer a competitive advantage. Our results highlight the need to consider the specific leaf hydraulic architecture of aridity-adapted plants when studying ecohydrological processes in arid ecosystems.

  11. Mangrove ecosystems under climate change

    Science.gov (United States)

    Jennerjahn, T.C.; Gilman, E.; Krauss, Ken W.; Lacerda, L.D.; Nordhaus, I.; Wolanski, E.

    2017-01-01

    This chapter assesses the response of mangrove ecosystems to possible outcomes of climate change, with regard to the following categories: (i) distribution, diversity, and community composition, (ii) physiology of flora and fauna, (iii) water budget, (iv) productivity and remineralization, (v) carbon storage in biomass and sediments, and (vi) the filter function for elements beneficial or harmful to life. These categories are then used to identify the regions most vulnerable to climate change. The four most important factors determining the response of mangrove ecosystems to climate change are sea level rise, an increase in frequency and/or intensity of storms, increases in temperature, and aridity. While these changes may be beneficial for some mangrove forests at latitudinal distribution limits, they will threaten forest structure and functions and related ecosystem services in most cases. The interaction of climate change with human interventions is discussed, as well as the effects on ecosystem services including possible adaptation and management options. The chapter closes with an outlook on knowledge gaps and priority research needed to fill these gaps.

  12. Analysis of the ecological conservation behavior of farmers in payment for ecosystem service programs in eco-environmentally fragile areas using social psychology models.

    Science.gov (United States)

    Deng, Jian; Sun, Pingsheng; Zhao, Fazhu; Han, Xinhui; Yang, Gaihe; Feng, Yongzhong

    2016-04-15

    Studies on the ecological conservation behavior of farmers usually focus on individual and socio-economic characteristics without consideration of the underlying psychological constructs, such as farmers' intention and perceptions. This study uses the theory of planned behavior (TPB), a typical social psychology construct, to analyze the factors affecting the intention and behavior of farmers for conserving the ecological achievements from payment for ecosystem service (PES) programs in eco-environmentally fragile areas. Questionnaires based on TPB were administered to 1004 farmers from the Grain to Green Program area in the Loess Plateau, China, with the resulting dataset used to identify the underlying factors determining farmers' intention and behavior based on the structural equation model. The results show that the farmers' intention and behavior toward conserving ecological achievements were explained well by TPB. The farmers'behavior was significantly positively affected by their intention toward conserving ecological achievements, and their intention was significantly influenced by their attitude (positive or negative value of performance), the subjective norm (social pressure in engaging behavior), and perceived behavioral control (perceptions of their ability). The farmers' degree of support for PES programs and their recognition of environmental effects were the factors that most influenced the farmers' attitude. Pressure from neighbors was the most potent driver of the subjective norm. Meanwhile, perceptions of their ability to perform the behavior were the most potent factors affecting intention and it was mostly driven by the farmers' feelings toward environmental improvement and perceived ability (time and labor) to participate in ecological conservation. The drivers of attitude, subjective norm, and perceived behavioral control can be used by policy makers to direct farmers' intention and behavior toward conserving ecological achievements in fragile

  13. Responses of LAI to rainfall explain contrasting sensitivities to carbon uptake between forest and non-forest ecosystems in Australia.

    Science.gov (United States)

    Li, Longhui; Wang, Ying-Ping; Beringer, Jason; Shi, Hao; Cleverly, James; Cheng, Lei; Eamus, Derek; Huete, Alfredo; Hutley, Lindsay; Lu, Xingjie; Piao, Shilong; Zhang, Lu; Zhang, Yongqiang; Yu, Qiang

    2017-09-15

    Non-forest ecosystems (predominant in semi-arid and arid regions) contribute significantly to the increasing trend and interannual variation of land carbon uptake over the last three decades, yet the mechanisms are poorly understood. By analysing the flux measurements from 23 ecosystems in Australia, we found the the correlation between gross primary production (GPP) and ecosystem respiration (Re) was significant for non-forest ecosystems, but was not for forests. In non-forest ecosystems, both GPP and Re increased with rainfall, and, consequently net ecosystem production (NEP) increased with rainfall. In forest ecosystems, GPP and Re were insensitive to rainfall. Furthermore sensitivity of GPP to rainfall was dominated by the rainfall-driven variation of LAI rather GPP per unit LAI in non-forest ecosystems, which was not correctly reproduced by current land models, indicating that the mechanisms underlying the response of LAI to rainfall should be targeted for future model development.

  14. Spatial heterogeneity of physicochemical properties explains differences in microbial composition in arid soils from Cuatro Cienegas, Mexico.

    Science.gov (United States)

    Pajares, Silvia; Escalante, Ana E; Noguez, Ana M; García-Oliva, Felipe; Martínez-Piedragil, Celeste; Cram, Silke S; Eguiarte, Luis Enrique; Souza, Valeria

    2016-01-01

    Arid ecosystems are characterized by high spatial heterogeneity, and the variation among vegetation patches is a clear example. Soil biotic and abiotic factors associated with these patches have also been well documented as highly heterogeneous in space. Given the low vegetation cover and little precipitation in arid ecosystems, soil microorganisms are the main drivers of nutrient cycling. Nonetheless, little is known about the spatial distribution of microorganisms and the relationship that their diversity holds with nutrients and other physicochemical gradients in arid soils. In this study, we evaluated the spatial variability of soil microbial diversity and chemical parameters (nutrients and ion content) at local scale (meters) occurring in a gypsum-based desert soil, to gain knowledge on what soil abiotic factors control the distribution of microbes in arid ecosystems. We analyzed 32 soil samples within a 64 m(2) plot and: (a) characterized microbial diversity using T-RFLPs of the bacterial 16S rRNA gene, (b) determined soil chemical parameters, and (c) identified relationships between microbial diversity and chemical properties. Overall, we found a strong correlation between microbial composition heterogeneity and spatial variation of cations (Ca(2), K(+)) and anions (HCO[Formula: see text], Cl(-), SO[Formula: see text]) content in this small plot. Our results could be attributable to spatial differences of soil saline content, favoring the patchy emergence of salt and soil microbial communities.

  15. Spatial heterogeneity of physicochemical properties explains differences in microbial composition in arid soils from Cuatro Cienegas, Mexico

    Directory of Open Access Journals (Sweden)

    Silvia Pajares

    2016-09-01

    Full Text Available Arid ecosystems are characterized by high spatial heterogeneity, and the variation among vegetation patches is a clear example. Soil biotic and abiotic factors associated with these patches have also been well documented as highly heterogeneous in space. Given the low vegetation cover and little precipitation in arid ecosystems, soil microorganisms are the main drivers of nutrient cycling. Nonetheless, little is known about the spatial distribution of microorganisms and the relationship that their diversity holds with nutrients and other physicochemical gradients in arid soils. In this study, we evaluated the spatial variability of soil microbial diversity and chemical parameters (nutrients and ion content at local scale (meters occurring in a gypsum-based desert soil, to gain knowledge on what soil abiotic factors control the distribution of microbes in arid ecosystems. We analyzed 32 soil samples within a 64 m2 plot and: (a characterized microbial diversity using T-RFLPs of the bacterial 16S rRNA gene, (b determined soil chemical parameters, and (c identified relationships between microbial diversity and chemical properties. Overall, we found a strong correlation between microbial composition heterogeneity and spatial variation of cations (Ca2, K+ and anions (HCO ${}_{3}^{-}$ 3 − , Cl−, SO ${}_{4}^{2-}$ 4 2 − content in this small plot. Our results could be attributable to spatial differences of soil saline content, favoring the patchy emergence of salt and soil microbial communities.

  16. Greening reclamation of arid region

    Energy Technology Data Exchange (ETDEWEB)

    Kamichika, Makio (Tottori Univ. (Japan))

    1989-01-20

    Arid regions occupy a third of the whole land in the world, and desertification in the rimland makes a problem become more acute. It is also a problem that the large part of such areas is distributed in developing countries. Desertification is defined as a phenomenon, by which the ecological system is degenerated by the change of weather conditions and the pressure of human beings and livestock, and productivity of land is markedly deteriorated. In order to prevent desertification and to promote greening reclamation and agricultural development, it is necessary to analyze desertification mechanism in detail. Artificial factors are overpopulation, too much pasturage, and conversion of grassland into farmland. Natural environmental factors are weather conditions, water resources, soil conditions, etc. It is also important for greening reclamation and development of farm land to evaluate the amount of meteorological resources (such as water resources, energy resources, etc.) and to search for the possibility of their utilization. Because of major condition to grow plants is water environment, investigation and development of water resources are important. If a project ignores the cycle of the ecological system, it might be in danger of retrogradation toward desertification. 8 refs., 10 figs., 4 tabs.

  17. Changes of AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China.

    Directory of Open Access Journals (Sweden)

    Yajun Hu

    Full Text Available Arbuscular mycorrhizal (AM fungi are ubiquitous symbionts of higher plants in terrestrial ecosystems, while the occurrence of the AM symbiosis is influenced by a complex set of abiotic and biotic factors. To reveal the regional distribution pattern of AM fungi as driven by multiple environmental factors, and to understand the ecological importance of AM fungi in natural ecosystems, we conducted a field investigation on AM fungal abundance along environmental gradients in the arid and semi-arid grasslands of northern China. In addition to plant parameters recorded in situ, soil samples were collected, and soil chemo-physical and biological parameters were measured in the lab. Statistical analyses were performed to reveal the relative contribution of climatic, edaphic and vegetation factors to AM fungal abundance, especially for extraradical hyphal length density (HLD in the soil. The results indicated that HLD were positively correlated with mean annual temperature (MAT, soil clay content and soil pH, but negatively correlated with both soil organic carbon (SOC and soil available N. The multiple regressions and structural equation model showed that MAT was the key positive contributor and soil fertility was the key negative contributor to HLD. Furthermore, both the intraradical AM colonization (IMC and relative abundance of AM fungi, which was quantified by real-time PCR assay, tended to decrease along the increasing SOC content. With regard to the obvious negative correlation between MAT and SOC in the research area, the positive correlation between MAT and HLD implied that AM fungi could potentially mitigate soil carbon losses especially in infertile soils under global warming. However, direct evidence from long-term experiments is still expected to support the AM fungal contribution to soil carbon pools.

  18. Contrasting responses of water use efficiency to drought across global terrestrial ecosystems.

    Science.gov (United States)

    Yang, Yuting; Guan, Huade; Batelaan, Okke; McVicar, Tim R; Long, Di; Piao, Shilong; Liang, Wei; Liu, Bing; Jin, Zhao; Simmons, Craig T

    2016-03-17

    Drought is an intermittent disturbance of the water cycle that profoundly affects the terrestrial carbon cycle. However, the response of the coupled water and carbon cycles to drought and the underlying mechanisms remain unclear. Here we provide the first global synthesis of the drought effect on ecosystem water use efficiency (WUE = gross primary production (GPP)/evapotranspiration (ET)). Using two observational WUE datasets (i.e., eddy-covariance measurements at 95 sites (526 site-years) and global gridded diagnostic modelling based on existing observation and a data-adaptive machine learning approach), we find a contrasting response of WUE to drought between arid (WUE increases with drought) and semi-arid/sub-humid ecosystems (WUE decreases with drought), which is attributed to different sensitivities of ecosystem processes to changes in hydro-climatic conditions. WUE variability in arid ecosystems is primarily controlled by physical processes (i.e., evaporation), whereas WUE variability in semi-arid/sub-humid regions is mostly regulated by biological processes (i.e., assimilation). We also find that shifts in hydro-climatic conditions over years would intensify the drought effect on WUE. Our findings suggest that future drought events, when coupled with an increase in climate variability, will bring further threats to semi-arid/sub-humid ecosystems and potentially result in biome reorganization, starting with low-productivity and high water-sensitivity grassland.

  19. An inventory and monitoring plan for a Sonoran Desert ecosystem; Barry M. Goldwater Range-West

    Science.gov (United States)

    Villarreal, Miguel L.; van Riper, Charles; Lovich, Robert E.; Palmer, Robert L.; Nauman, Travis; Studd, Sarah E.; Drake, Sam; Rosenberg, Abigail S.; Malusa, Jim; Pearce, Ronald L.

    2011-01-01

    Marine Corps Air Station Yuma manages the Barry M. Goldwater Range-West, which encompasses approximately 2,800 square kilometers of Sonoran Desert habitat in southwestern Arizona. The Barry M. Goldwater Range is a major U.S. military installation designed as an air combat training location for the U.S. Marine Corps and U.S. Air Force, but it also includes some of the most pristine desert habitat in the United States. In an effort to ensure the long-term viability of this unique natural resource, the U.S. Geological Survey (USGS) has developed an Integrated Natural Resources Management Plan and Inventory and Monitoring Plan to guide natural resource management of the Barry M. Goldwater Range-West. This Inventory and Monitoring Plan provides a framework for long-term ecosystem monitoring on Barry M. Goldwater Range-West lands by identifying existing and potential threats to ecosystem function, prioritizing resources for monitoring, and providing information and protocols necessary to initiate a long-term ecosystem monitoring program. The Inventory and Monitoring Plan and related protocols were developed through extensive review of existing Sonoran Desert monitoring programs and monitoring literature and through a 2-day workshop with resource managers, monitoring experts, and other stakeholders. The Barry M. Goldwater Range-West Inventory and Monitoring Plan stresses the importance of regional monitoring partnerships and protocol standardization for understanding landscape-scale ecosystem changes in the Sonoran Desert; information and protocols contained within the plan may also be of interest to land managers engaged in large-scale ecosystem monitoring and adaptive management of other arid regions.

  20. Precipitation pattern determines the inter-annual variation of herbaceous layer and carbon fluxes in a shrub-dominated desert ecosystem

    NARCIS (Netherlands)

    Liu, R.; Cieraad, E.; Li, Y.; Ma, J.

    2016-01-01

    Arid and semi-arid ecosystems dominated by shrubby species are an important component in the global carbon cycle but are largely under-represented in studies of the effect of climate change on carbon flux. This study synthesizes data from long-term eddy covariance measurements and experiments to

  1. The characterisation of rainfall in the arid and semi-arid regions of ...

    African Journals Online (AJOL)

    of rainfall. Although it is one of the most drought-hit countries in the world, almost no study has ever been conducted in characterising the rainfall pattern of the arid and semi-arid regions of Ethiopia. In this study, rainfall data of the past 50 years was used to study the basic statistical characteristics of the rainfall of this region.

  2. Evaluating rainwater harvesting systems in arid and semi-arid regions

    NARCIS (Netherlands)

    Ammar, Adham Ali

    2017-01-01

    Rainwater harvesting (RWH) is an ancient traditional technology practised in many parts of the world, especially in arid and semi-arid regions (ASARs). ASARs represent 40% of the earth’s land surface and are characterised by low average annual rainfall and uneven temporal and spatial

  3. Greenhouse technology for cultivation in arid and semi-arid regions

    NARCIS (Netherlands)

    Baeza Romero, Esteban; Kacira, M.

    2017-01-01

    Greenhouses have expanded from Northern areas to other climatic regions in the world, including arid and semi-arid regions. The main limiting factors for greenhouse cultivation in such areas are the high ambient temperatures with low humidity (sometimes with high humidity in coastal areas), typical

  4. Fitting rainfall interception models to forest ecosystems of Mexico

    Science.gov (United States)

    Návar, José

    2017-05-01

    Models that accurately predict forest interception are essential both for water balance studies and for assessing watershed responses to changes in land use and the long-term climate variability. This paper compares the performance of four rainfall interception models-the sparse Gash (1995), Rutter et al. (1975), Liu (1997) and two new models (NvMxa and NvMxb)-using data from four spatially extensive, structurally diverse forest ecosystems in Mexico. Ninety-eight case studies measuring interception in tropical dry (25), arid/semi-arid (29), temperate (26), and tropical montane cloud forests (18) were compiled and analyzed. Coefficients derived from raw data or published statistical relationships were used as model input to evaluate multi-storm forest interception at the case study scale. On average empirical data showed that, tropical montane cloud, temperate, arid/semi-arid and tropical dry forests intercepted 14%, 18%, 22% and 26% of total precipitation, respectively. The models performed well in predicting interception, with mean deviations between measured and modeled interception as a function of total precipitation (ME) generally 0.66. Model fitting precision was dependent on the forest ecosystem. Arid/semi-arid forests exhibited the smallest, while tropical montane cloud forest displayed the largest ME deviations. Improved agreement between measured and modeled data requires modification of in-storm evaporation rate in the Liu; the canopy storage in the sparse Gash model; and the throughfall coefficient in the Rutter and the NvMx models. This research concludes on recommending the wide application of rainfall interception models with some caution as they provide mixed results. The extensive forest interception data source, the fitting and testing of four models, the introduction of a new model, and the availability of coefficient values for all four forest ecosystems are an important source of information and a benchmark for future investigations in this

  5. Life at the hyperarid margin: novel bacterial diversity in arid soils of the Atacama Desert, Chile

    Science.gov (United States)

    Neilson, Julia W.; Quade, Jay; Ortiz, Marianyoly; Nelson, William M.; Legatzki, Antje; Tian, Fei; LaComb, Michelle; Betancourt, Julio L.; Wing, Rod A.; Soderlund, Carol A.; Maier, Raina M.

    2012-01-01

    Nearly half the earth's surface is occupied by dryland ecosystems, regions susceptible to reduced states of biological productivity caused by climate fluctuations. Of these regions, arid zones located at the interface between vegetated semiarid regions and biologically unproductive hyperarid zones are considered most vulnerable. The objective of this study was to conduct a deep diversity analysis of bacterial communities in unvegetated arid soils of the Atacama Desert, to characterize community structure and infer the functional potential of these communities based on observed phylogenetic associations. A 454-pyrotag analysis was conducted of three unvegetated arid sites located at the hyperarid-arid margin. The analysis revealed communities with unique bacterial diversity marked by high abundances of novel Actinobacteria and Chloroflexi and low levels of Acidobacteria and Proteobacteria, phyla that are dominant in many biomes. A 16S rRNA gene library of one site revealed the presence of clones with phylogenetic associations to chemoautotrophic taxa able to obtain energy through oxidation of nitrite, carbon monoxide, iron, or sulfur. Thus, soils at the hyperarid margin were found to harbor a wealth of novel bacteria and to support potentially viable communities with phylogenetic associations to non-phototrophic primary producers and bacteria capable of biogeochemical cycling.

  6. 75 years of dryland science: Trends and gaps in arid ecology literature.

    Science.gov (United States)

    Greenville, Aaron C; Dickman, Chris R; Wardle, Glenda M

    2017-01-01

    Growth in the publication of scientific articles is occurring at an exponential rate, prompting a growing need to synthesise information in a timely manner to combat urgent environmental problems and guide future research. Here, we undertake a topic analysis of dryland literature over the last 75 years (8218 articles) to identify areas in arid ecology that are well studied and topics that are emerging. Four topics-wetlands, mammal ecology, litter decomposition and spatial modelling, were identified as 'hot topics' that showed higher than average growth in publications from 1940 to 2015. Five topics-remote sensing, climate, habitat and spatial, agriculture and soils-microbes, were identified as 'cold topics', with lower than average growth over the survey period, but higher than average numbers of publications. Topics in arid ecology clustered into seven broad groups on word-based similarity. These groups ranged from mammal ecology and population genetics, broad-scale management and ecosystem modelling, plant ecology, agriculture and ecophysiology, to populations and paleoclimate. These patterns may reflect trends in the field of ecology more broadly. We also identified two broad research gaps in arid ecology: population genetics, and habitat and spatial research. Collaborations between population genetics and ecologists and investigations of ecological processes across spatial scales would contribute profitably to the advancement of arid ecology and to ecology more broadly.

  7. Agricultural intensification and drought frequency increases may have landscape-level consequences for ephemeral ecosystems.

    Science.gov (United States)

    Dalu, Tatenda; Wasserman, Ryan J; Dalu, Mwazvita T B

    2017-03-01

    Ephemeral wetlands in arid regions are often degraded or destroyed through poor land-use practice long before they are ever studied or prioritized for conservation. Climate change will likely also have implications for these ecosystems given forecast changes in rainfall patterns in many arid environments. Here, we present a conceptual diagram showing typical and modified ephemeral wetlands in agricultural landscapes and how modification impacts on species diversity and composition. © 2016 John Wiley & Sons Ltd.

  8. Is annual recharge coefficient a valid concept in arid and semi-arid regions?

    Science.gov (United States)

    Cheng, Yiben; Zhan, Hongbin; Yang, Wenbin; Dang, Hongzhong; Li, Wei

    2017-10-01

    Deep soil recharge (DSR) (at depth greater than 200 cm) is an important part of water circulation in arid and semi-arid regions. Quantitative monitoring of DSR is of great importance to assess water resources and to study water balance in arid and semi-arid regions. This study used a typical bare land on the eastern margin of Mu Us Sandy Land in the Ordos Basin of China as an example to illustrate a new lysimeter method of measuring DSR to examine if the annual recharge coefficient is valid or not in the study site, where the annual recharge efficient is the ratio of annual DSR over annual total precipitation. Positioning monitoring was done on precipitation and DSR measurements underneath mobile sand dunes from 2013 to 2015 in the study area. Results showed that use of an annual recharge coefficient for estimating DSR in bare sand land in arid and semi-arid regions is questionable and could lead to considerable errors. It appeared that DSR in those regions was influenced by precipitation pattern and was closely correlated with spontaneous strong precipitation events (with precipitation greater than 10 mm) other than the total precipitation. This study showed that as much as 42 % of precipitation in a single strong precipitation event can be transformed into DSR. During the observation period, the maximum annual DSR could make up 24.33 % of the annual precipitation. This study provided a reliable method of estimating DSR in sandy areas of arid and semi-arid regions, which is valuable for managing groundwater resources and ecological restoration in those regions. It also provided strong evidence that the annual recharge coefficient was invalid for calculating DSR in arid and semi-arid regions. This study shows that DSR is closely related to the strong precipitation events, rather than to the average annual precipitation, as well as the precipitation patterns.

  9. Assessing Riparian Vegetation Condition and Function in Disturbed Sites of the Arid Northwestern Mexico

    Directory of Open Access Journals (Sweden)

    Lara Cornejo-Denman

    2018-01-01

    Full Text Available Transformation or modification of vegetation distribution and structure in arid riparian ecosystems can lead to the loss of ecological function. Mexico has 101,500,000 ha of arid lands, however there is a general lack of information regarding how arid riparian ecosystems are being modified. To assess these modifications, we use eight sites in the San Miguel River (central Sonora to analyze (1 riparian vegetation composition, structure and distribution using field sampling and remote sensing data from Unmanned Aerial Vehicles (UAV; (2 productivity (proxies, using vegetation indices derived from satellite data; and (3 variability posed by riparian vegetation and vegetation adjacent to riparian habitats. The development of a simple yet informative Anthropogenic-disturbance Index (ADI allowed us to classify and describe each study site. We found sharp differences in vegetation composition and structure between sites due to the absence/presence of obligate-riparian species. We also report significant difference between EVI (Enhanced Vegetation Index values for the dry season among vegetation types that develop near the edges of the river but differ in composition, suggesting that land cover changes form obligate-riparian to facultative-riparian species can lead to a loss in potential productivity. Finally, our tests suggest that sites with higher disturbance present lower photosynthetic activity.

  10. The Florida Seagrass Integrated Mapping and Monitoring (SIMM) Program: Indications of the effects of regional climate variability on these vital ecosystems

    Science.gov (United States)

    Yarbro, L.; Carlson, P. R., Jr.

    2016-12-01

    The SIMM program was developed to protect and manage seagrass resources in Florida by providing a collaborative vehicle for seagrass mapping, monitoring, data sharing, and reporting. We summarize and interpret mapping data and field assessments of seagrass abundance and diversity and water quality gathered by regional scientists and managers who work in estuaries from the Panhandle to the northeast Florida coast. Since 2013, regional reports summarizing the status and trends of seagrass ecosystems have been available on the web. The format provides current information for a wide stakeholder community. Ongoing collaborative efforts of more than 30 seagrass researchers and managers provide timely information on environmental and ecosystem changes in these important systems. Since the first published seagrass assessments in 2009, we have observed large changes in seagrass abundance and diversity in several regions; most but not all changes were likely due to variations in water quality that determine the light available to benthic vegetation. In the Panhandle and the Big Bend, in 2012-2104, increases in the frequency and severity of storms and resulting runoff reduced water quality which in turn decreased the abundance and distribution of seagrasses. The storm pattern resulted from changes in the subtropical jet stream and persisted for 3 years. In south Florida, heat and drought elevated salinities to extreme levels in Florida Bay in 2015; the resulting stratification along with high temperatures caused die-off of thousands of hectares of seagrass in the north central Bay. Extremely wet conditions in southeast Florida in 2015-2016 strained the water management system, resulting in large releases of polluted freshwater to estuaries on the southwest and southeast coasts, reducing light availability and causing large blooms of noxious algae. While other regions have also experienced algal blooms that reduced available light (Indian River Lagoon), seagrasses have

  11. Increasing aridity, temperature and soil pH induce soil C-N-P imbalance in grasslands

    Science.gov (United States)

    Jiao, Feng; Shi, Xin-Rong; Han, Feng-Peng; Yuan, Zhi-You

    2016-01-01

    Due to the different degrees of controls exerted by biological and geochemical processes, climate changes are suggested to uncouple biogeochemical C, N and P cycles, influencing biomass accumulation, decomposition and storage in terrestrial ecosystems. However, the possible extent of such disruption in grassland ecosystems remains unclear, especially in China’s steppes which have undergone rapid climate changes with increasing drought and warming predicted moving forward in these dryland ecosystems. Here, we assess how soil C-N-P stoichiometry is affected by climatic change along a 3500-km temperate climate transect in Inner Mongolia, China. Our results reveal that the soil from more arid and warmer sites are associated with lower soil organic C, total N and P. The ratios of both soil C:P and N:P decrease, but soil C:N increases with increasing aridity and temperature, indicating the predicted decreases in precipitation and warming for most of the temperate grassland region could lead to a soil C-N-P decoupling that may reduce plant growth and production in arid ecosystems. Soil pH, mainly reflecting long-term climate change in our sites, also contributes to the changing soil C-N-P stoichiometry, indicating the collective influences of climate and soil type on the shape of soil C-N-P balance.

  12. Indicators of change in the organic matter in arid soils.

    Science.gov (United States)

    Oyonarte, Cecilio; Mingorance, María Dolores; Durante, Pilar; Piñero, Gervasio; Barahona, Enrique

    2007-05-25

    Soil organic matter is a key component in ecosystems, as it is the essential part of a set of relevant processes and constitutes an important carbon pool contributing to Global Change. The design of environmental monitoring programmes should include indicators of the current status of ecosystems, alerting to incipient changes in them. In this context, a sampling scheme has been designed taking into account the main processes and soil uses affecting the dynamics of soil organic matter. Well-tested parameters were determined in order to assess which of them are most useful as indicators of soil organic matter evolution in arid soil, such as that in the "Cabo de Gata-Níjar" Natural Park (SE Spain). The parameters characterising the lability of the different fractions indicate changes in soil organic matter triggered by changes in soil use and soil dynamics. Changes in soil use, when drastic, are best reflected by those fractions comprising a high percentage of the total soil carbon, while the processes having slower dynamics are best demonstrated by the labile fractions. As a result of the sensitivity analysis of parameters versus changes, and taking into account the operational difficulties for determining them, the following indicators are proposed for a monitoring programme: total organic carbon, active fraction of the organic carbon and ratios of this fraction versus total organic carbon (%) (as given by the lability index proposed).

  13. Evaluating the generalizability of GEP models for estimating reference evapotranspiration in distant humid and arid locations

    Science.gov (United States)

    Kiafar, Hamed; Babazadeh, Hosssien; Marti, Pau; Kisi, Ozgur; Landeras, Gorka; Karimi, Sepideh; Shiri, Jalal

    2017-10-01

    Evapotranspiration estimation is of crucial importance in arid and hyper-arid regions, which suffer from water shortage, increasing dryness and heat. A modeling study is reported here to cross-station assessment between hyper-arid and humid conditions. The derived equations estimate ET0 values based on temperature-, radiation-, and mass transfer-based configurations. Using data from two meteorological stations in a hyper-arid region of Iran and two meteorological stations in a humid region of Spain, different local and cross-station approaches are applied for developing and validating the derived equations. The comparison of the gene expression programming (GEP)-based-derived equations with corresponding empirical-semi empirical ET0 estimation equations reveals the superiority of new formulas in comparison with the corresponding empirical equations. Therefore, the derived models can be successfully applied in these hyper-arid and humid regions as well as similar climatic contexts especially in data-lack situations. The results also show that when relying on proper input configurations, cross-station might be a promising alternative for locally trained models for the stations with data scarcity.

  14. A method to identify the variable ecosystem services relationship across time: a case study on Yanhe Basin, China

    Science.gov (United States)

    Zhenmin Zheng; Bojie Fu; Haitang Hu; Ge Sun

    2014-01-01

    Ecosystem services are increasingly recognized as the foundations of a well-functioning society. Large-scale ecological restoration projects have been implemented around China with the goal of restoring and sustaining ecosystem services, especially in vulnerable semi-arid regions where soil and water resources are most stressed due to historic human activities. The...

  15. Mapping groundwater dependent ecosystems in California.

    Directory of Open Access Journals (Sweden)

    Jeanette Howard

    Full Text Available BACKGROUND: Most groundwater conservation and management efforts focus on protecting groundwater for drinking water and for other human uses with little understanding or focus on the ecosystems that depend on groundwater. However, groundwater plays an integral role in sustaining certain types of aquatic, terrestrial and coastal ecosystems, and their associated landscapes. Our aim was to illuminate the connection between groundwater and surface ecosystems by identifying and mapping the distribution of groundwater dependent ecosystems (GDEs in California. METHODOLOGY/PRINCIPAL FINDINGS: To locate where groundwater flow sustains ecosystems we identified and mapped groundwater dependent ecosystems using a GIS. We developed an index of groundwater dependency by analyzing geospatial data for three ecosystem types that depend on groundwater: (1 springs and seeps; (2 wetlands and associated vegetation alliances; and (3 stream discharge from groundwater sources (baseflow index. Each variable was summarized at the scale of a small watershed (Hydrologic Unit Code-12; mean size = 9,570 ha; n = 4,621, and then stratified and summarized to 10 regions of relative homogeneity in terms of hydrologic, ecologic and climatic conditions. We found that groundwater dependent ecosystems are widely, although unevenly, distributed across California. Although different types of GDEs are clustered more densely in certain areas of the state, watersheds with multiple types of GDEs are found in both humid (e.g. coastal and more arid regions. Springs are most densely concentrated in the North Coast and North Lahontan, whereas groundwater dependent wetlands and associated vegetation alliances are concentrated in the North and South Lahontan and Sacramento River hydrologic regions. The percentage of land area where stream discharge is most dependent on groundwater is found in the North Coast, Sacramento River and Tulare Lake regions. GDE clusters are located at the highest

  16. Mapping Groundwater Dependent Ecosystems in California

    Science.gov (United States)

    Howard, Jeanette; Merrifield, Matt

    2010-01-01

    Background Most groundwater conservation and management efforts focus on protecting groundwater for drinking water and for other human uses with little understanding or focus on the ecosystems that depend on groundwater. However, groundwater plays an integral role in sustaining certain types of aquatic, terrestrial and coastal ecosystems, and their associated landscapes. Our aim was to illuminate the connection between groundwater and surface ecosystems by identifying and mapping the distribution of groundwater dependent ecosystems (GDEs) in California. Methodology/Principal Findings To locate where groundwater flow sustains ecosystems we identified and mapped groundwater dependent ecosystems using a GIS. We developed an index of groundwater dependency by analyzing geospatial data for three ecosystem types that depend on groundwater: (1) springs and seeps; (2) wetlands and associated vegetation alliances; and (3) stream discharge from groundwater sources (baseflow index). Each variable was summarized at the scale of a small watershed (Hydrologic Unit Code-12; mean size = 9,570 ha; n = 4,621), and then stratified and summarized to 10 regions of relative homogeneity in terms of hydrologic, ecologic and climatic conditions. We found that groundwater dependent ecosystems are widely, although unevenly, distributed across California. Although different types of GDEs are clustered more densely in certain areas of the state, watersheds with multiple types of GDEs are found in both humid (e.g. coastal) and more arid regions. Springs are most densely concentrated in the North Coast and North Lahontan, whereas groundwater dependent wetlands and associated vegetation alliances are concentrated in the North and South Lahontan and Sacramento River hydrologic regions. The percentage of land area where stream discharge is most dependent on groundwater is found in the North Coast, Sacramento River and Tulare Lake regions. GDE clusters are located at the highest percentage

  17. Characterizing the performance of ecosystem models across time scales: A spectral analysis of the North American Carbon Program site-level synthesis

    Science.gov (United States)

    Michael C. Dietze; Rodrigo Vargas; Andrew D. Richardson; Paul C. Stoy; Alan G. Barr; Ryan S. Anderson; M. Altaf Arain; Ian T. Baker; T. Andrew Black; Jing M. Chen; Philippe Ciais; Lawrence B. Flanagan; Christopher M. Gough; Robert F. Grant; David Hollinger; R. Cesar Izaurralde; Christopher J. Kucharik; Peter Lafleur; Shugang Liu; Erandathie Lokupitiya; Yiqi Luo; J. William Munger; Changhui Peng; Benjamin Poulter; David T. Price; Daniel M. Ricciuto; William J. Riley; Alok Kumar Sahoo; Kevin Schaefer; Andrew E. Suyker; Hanqin Tian; Christina Tonitto; Hans Verbeeck; Shashi B. Verma; Weifeng Wang; Ensheng Weng

    2011-01-01

    Ecosystem models are important tools for diagnosing the carbon cycle and projecting its behavior across space and time. Despite the fact that ecosystems respond to drivers at multiple time scales, most assessments of model performance do not discriminate different time scales. Spectral methods, such as wavelet analyses, present an alternative approach that enables the...

  18. Research Award: Ecosystems and Human Health (Ecohealth)

    International Development Research Centre (IDRC) Digital Library (Canada)

    Corey Piccioni

    2013-08-07

    Aug 7, 2013 ... IDRC's Ecosystems and Human Health (Ecohealth) program explores the links between human health and well‐being and producve and sustainable ecosystems. Read more about past and current projects funded by the Ecohealth program. As a transdiciplinary and applied research approach, ecohealth ...

  19. Analysis of the feasibility to integrate the semi-arid family agriculture in the National Program for Production and Use of Biodiesel: Ceara case, Brazil; Analise da viabilidade para insercao da agricultura familiar do semiarido no Programa Nacional de Producao e Uso de Biodiesel: o caso do Ceara

    Energy Technology Data Exchange (ETDEWEB)

    Siniscalchi, Carina Renno

    2010-03-15

    In 2004, it was established the National Program for Production and Use of Biodiesel (PNPB) which encourages the participation of family farming in the biodiesel production chain, boosting rural development and social inclusion of these workers. From 2008 on, the PNPB decided that it would be mandatory the add 2% of biodiesel into diesel, named B2, and from 2010 on, the obligation of B5 was imposed. However, after two years of mandatory mixing, over 80% of the raw material for biodiesel production comes from large producers of soybeans in the Midwest. Thus, the focus of this study was to identify the main constraints and opportunities for family farming to participate in the program, based on the analysis of design parameters and guiding PNPB and the main stages of the agricultural seeds in the semi-arid. The study focused on Ceara as it is the state that greatly encourages the participation of small farmers through subsidies associated with the adoption of agro-ecological farming practices (author)

  20. Using Soil Amendments to Improve Riparian Plant Survival in Arid and Semi-arid Landscapes

    National Research Council Canada - National Science Library

    Fischer, Richard

    2004-01-01

    .... In addition, plant establishment can be difficult in arid regions since many stream and riparian areas are characterized by infertile or highly saline soils, very low rainfall, narrow planting...

  1. Applying animal behavior to arid rangeland mangement

    Science.gov (United States)

    Livestock production is one of many demands placed on today’s arid rangelands. Therefore, understanding plant and animal biology and their effects on biotic and abiotic landscape components is fundamental if rangelands are to remain ecologically sustainable. One limiting factor to accomplishing posi...

  2. 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

  3. Remediation of metalliferous mines, revegetation challenges and emerging prospects in semi-arid and arid conditions.

    Science.gov (United States)

    Nirola, Ramkrishna; Megharaj, Mallavarapu; Beecham, Simon; Aryal, Rupak; Thavamani, Palanisami; Vankateswarlu, Kadiyala; Saint, Christopher

    2016-10-01

    Understanding plant behaviour in polluted soils is critical for the sustainable remediation of metal-polluted sites including abandoned mines. Post-operational and abandoned metal mines particularly in semi-arid and arid zones are one of the major sources of pollution by soil erosion or plant hyperaccumulation bringing ecological impacts. We have selected from the literature 157 species belonging to 50 families to present a global overview of 'plants under action' against heavy metal pollution. Generally, all species of plants that are drought, salt and metal tolerant are candidates of interest to deal with harsh environmental conditions, particularly at semi-arid and arid mine sites. Pioneer metallophytes namely Atriplex nummularia, Atriplex semibaccata, Salsola kali, Phragmites australis and Medicago sativa, representing the taxonomic orders Caryophyllales, Poales and Fabales are evaluated in terms of phytoremediation in this review. Phytoremediation processes, microbial and algal bioremediation, the use and implication of tissue culture and biotechnology are critically examined. Overall, an integration of available remediation plant-based technologies, referred to here as 'integrated remediation technology,' is proposed to be one of the possible ways ahead to effectively address problems of toxic heavy metal pollution. Graphical abstract Integrated remediation technology (IRT) in metal-contaminated semi-arid and arid conditions. The hexagonal red line represents an IRT concept based on remediation decisions by combination of plants and microbial processes.

  4. Statistical Change Detection in Dust Storm Frequency Across Arid and Semi-arid Regions of Iran

    Science.gov (United States)

    Modarres, R.; Sadeghi, S.; Sarhadi, A.

    2016-12-01

    Arid and semi-arid regions cover 60% of Iran which are surrendered by two major mountains in the north and west of the country. This central region of Iran not only receives very low amount of rainfall but also suffers from high human induced intense land degradation. These conditions have been leading to frequent dust storms which have been influencing soil erosion and population migration. In this study the spatial and temporal change in dust storm occurrence is investigated over arid and semi-arid region of Iran. The annual number of dust storms was collected from 22 stations for 1951-2010 period and nonparametric methods were used to detect both monotonic trend and change point in these annual time series. The number of dust storm increases from the northern reigns to the south eastern territories where climate conditions are influenced by rainfall reduction and increasing drought frequency. The trend assessment indicate negative trend of dust storm occurrence in the north and increasing trend for the southeastern territories of the region. The change point detection method also indicates the 1970 and 1980 decades have most frequent and significant change points of dust storm appearance over arid and semi-arid regions of Iran. Using Wilcoxon, Levene and Kolmogorov Smirnov tests reveal statistically significant shift in the mean, variance and frequency distribution of dust storm occurrence after the change point.

  5. 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

  6. Microclimates of the arid lands ecology reserve, 1968--1975

    Energy Technology Data Exchange (ETDEWEB)

    Thorp, J. M.; Hinds, W. T.

    1977-04-01

    The climatology of the Hanford Reservation Arid Lands Ecology (ALE) Reserve does not end, of course, with this report. As this goes to press the arid lands of eastern Washington are experiencing the driest winter in 65 years of record. Even without including this winter's (1976-77) data in our summaries here, we have been fortunate to have had a very dry winter (1972-73) and a very wet winter (1973-74) occur within our first 8 years of climatological measurements on the Reserve. Our primary purpose with this report has been to analyze the first 8 years of climatological measurements from the ALE Reserve and to identify persistent spatial variations between stations or groups of stations. From these variations we have been able to recognize several distinct, but related microclimates occurring within the Reserve. Secondly, we have shown that significant correlations exist between each microclimate on the Reserve and that of the Hanford Meteorological Station nearby. These correlations, coupled with the 30-year weather record at the HMS and possibly with the 32-year (1912-1944) record at the Hanford townsite, allow ALE Reserve temperature and precipitation estimates to be made for years prior to the ALE climatology program.

  7. Nitrate in shallow groundwater in typical agricultural and forest ecosystems in China, 2004-2010.

    Science.gov (United States)

    Zhang, Xinyu; Xu, Zhiwei; Sun, Xiaomin; Dong, Wenyi; Ballantine, Deborah

    2013-05-01

    The nitrate-nitrogen (NO3(-)-N) concentrations from shallow groundwater wells situated in 29 of the Chinese Ecosystem Research Network field stations, representing typical agro- and forest ecosystems, were assessed using monitoring data collected between 2004 and 2010. Results from this assessment permit a national scale assessment of nitrate concentrations in shallow groundwater, and allow linkages between nitrate concentrations in groundwater and broad land use categories to be made. Results indicated that most of the NO3(-)-N concentrations in groundwater from the agro- and forest ecosystems were below the Class 3 drinking water standard stated in the Chinese National Standard: Quality Standard for Ground Water ( 10 mg N /L) in 10 of the 43 wells sampled in the agricultural ecosystems. These elevated concentrations occurred mainly in the Ansai, Yucheng, Linze, Fukang, Akesu, and Cele field sites, which were located in arid and semi-arid areas where irrigation rates are high. We suggest that improvements in N fertilizer application and irrigation management practices in the arid and semi-arid agricultural ecosystems of China are the key to managing groundwater nitrate concentrations.

  8. Integral assessment of pollution in the Suquía River (Córdoba, Argentina) as a contribution to lotic ecosystem restoration programs.

    Science.gov (United States)

    Merlo, C; Abril, A; Amé, M V; Argüello, G A; Carreras, H A; Chiappero, M S; Hued, A C; Wannaz, E; Galanti, L N; Monferrán, M V; González, C M; Solís, V M

    2011-11-01

    The Suquía River lower-middle basin (Córdoba, Argentina) is subject to a strong anthropic impact because it receives pollutants from different sources (industries, wastewaters, heavy traffic, agricultural land use, etc.) We have assessed the degree of watershed degradation of Suquía River lower-middle sections through the analysis of different ecosystem compartments (air, water, riparian soil, sediments and biota), in order to provide useful data to be considered in future river restoration programs. Four study sites were selected along the river (La Calera city, Córdoba city, Corazón de María village and Río Primero city) which were sampled during the low- and high-water flow periods. We analyzed: a) chemical and physical characteristics of water, sediments, and riparian soil; b) heavy metal content of water and sediments, and c) semi-volatile organic compounds in air. Besides, pollutant bioindicators such as fish assemblages, lichens (Usnea amblyoclada), vascular plants (Tradescantia pallida), and microorganisms (fecal coliform and Escherichia coli) were used to further assess the status of the river. All analyzed ecological compartments were affected by water pollution, particularly, fish assemblages, sediments and riparian soils by heavy metal and coliform bacteria. Moreover, we detected a possible contribution of sulfur and a high pollutant content in air that merit further research about other air-water exchanges. Accordingly, we strongly suggest that an action to restore or remediate the anthropic effect on the Suquía River be extended to all possible compartments along the river. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Biomimicry as an approach for sustainable architecture case of arid regions with hot and dry climate

    Science.gov (United States)

    Bouabdallah, Nabila; M'sellem, Houda; Alkama, Djamel

    2016-07-01

    This paper aims to study the problem of thermal comfort inside buildings located in hot and arid climates. The principal idea behind this research is using concepts based on the potential of nature as an instrument that helps creating appropriate facades with the environment "building skin". The biomimetic architecture imitates nature through the study of form, function, behaviour and ecosystems of biological organisms. This research aims to clarify the possibilities that can be offered by biomimicry architecture to develop architectural bio-inspired building's design that can help to enhance indoor thermal ambiance in buildings located in hot and dry climate which helps to achieve thermal comfort for users.

  10. Endemic shrubs in temperate arid and semiarid regions of northern China and their potentials for rangeland restoration.

    Science.gov (United States)

    Chu, Jianmin; Yang, Hongxiao; Lu, Qi; Zhang, Xiaoyan

    2015-06-03

    Some endemic shrubs in arid and semiarid ecosystems are in danger of extinction, and yet they can play useful roles in maintaining or restoring these ecosystems, thus practical efforts are needed to conserve them. The shrubs Amygdalus pedunculata Pall., Amygdalus mongolica (Maxim.) Ricker and Ammopiptanthus mongolicus (Maxim. ex Kom.) Cheng f. are endemic species in arid and semiarid regions of northern China, where rangeland desertification is pronounced due to chronic overgrazing. In this study, we tested the hypothesis that these endemic shrubs have developed adaptations to arid and semiarid environments and could play critical roles as nurse species to initiate the process of rangeland recovery. Based on careful vegetation surveys, we analysed the niches of these species in relation to precipitation, temperature and habitats. All sampling plots were categorized by these endemics and sorted by the non-metric multidimensional scaling method. Species ratios of each life form and species co-occurrence rates with the endemics were also evaluated. Annual average temperature and annual precipitation were found to be the key factors determining vegetation diversity and distributions. Amygdalus pedunculata prefers low hills and sandy land in temperate semiarid regions. Amygdalus mongolica prefers gravel deserts of temperate semiarid regions. Ammopiptanthus mongolicus prefers sandy land of temperate arid regions. Communities of A. pedunculata have the highest diversity and the largest ratios of long-lived grass species, whereas those of A. mongolicus have the lowest diversity but the largest ratios of shrub species. Communities of A. mongolica are a transition between the first two community types. These findings demonstrate that our focal endemic shrubs have evolved adaptations to arid and semiarid conditions, thus they can be nurse plants to stabilize sand ground for vegetation restoration. We suggest that land managers begin using these shrub species to restore

  11. Ground Monitoring Neotropical Dry Forests: A Sensor Network for Forest and Microclimate Dynamics in Semi-Arid Environments (Enviro-Net°)

    Science.gov (United States)

    Rankine, C. J.; Sánchez-Azofeifa, G.

    2011-12-01

    In the face of unprecedented global change driven by anthropogenic pressure on natural systems it has become imperative to monitor and better understand potential shifts in ecosystem functioning and services from local to global scales. The utilization of automated sensors technologies offers numerous advantages over traditional on-site ecosystem surveying techniques and, as a result, sensor networks are becoming a powerful tool in environmental monitoring programs. Tropical forests, renowned for their biodiversity, are important regulators of land-atmosphere fluxes yet the seasonally dry tropical forests, which account for 40% of forested ecosystems in the American tropics, have been severely degraded over the past several decades and not much is known of their capacity to recover. With less than 1% of these forests protected, our ability to monitor the dynamics and quantify changes in the remaining primary and recovering secondary tropical dry forests is vital to understanding mechanisms of ecosystem stress responses and climate feedback with respect to annual productivity and desertification processes in the tropics. The remote sensing component of the Tropi-Dry: Human and Biophysical Dimensions of Tropical Dry Forests in the Americas research network supports a network of long-term tropical ecosystem monitoring platforms which focus on the dynamics of seasonally dry tropical forests in the Americas. With over 25 sensor station deployments operating across a latitudinal gradient in Mexico, Costa Rica, Brazil, and Argentina continuously collecting hyper-temporal sensory input based on standardized deployment parameters, this monitoring system is unique among tropical environments. Technologies used in the network include optical canopy phenology towers, understory wireless sensing networks, above and below ground microclimate stations, and digital cameras. Sensory data streams are uploaded to a cyber-infrastructure initiative, denominated Enviro-Net°, for data

  12. 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.

  13. Richness and distribution of aquatic macrophytes in Brazilian semi-arid aquatic ecosystems Riqueza e distribuição de macrófitas aquáticas em ecossistemas aquáticos do semi-árido brasileiro

    Directory of Open Access Journals (Sweden)

    Gustavo Gonzaga Henry-Silva

    2010-06-01

    Full Text Available AIM: The aim of this study was to evaluate the richness and distribution of the aquatic macrophytes in the basin of the Apodi/Mossoró River, in the semi-arid region (caatinga of Rio Grande do Norte, Brazil; METHODS: A survey of the floristic composition of the aquatic macrophytes was made at 20 sampling stations in the basin at four seasons (August/2007, November/2007, February/2008, May/2008. Specimens of each species were collected and deposited in the Dárdano de Andrade Lima Herbarium of the Universidade Federal Rural do Semi-Árido; RESULTS: We found 40 species of aquatic macrophytes, in 33 genera and 22 families. The families with the most species were Poaceae and Cyperaceae, and the most species-rich genera were Cyperus and Eleocharis. The most common plant form was amphibian (42.5%, followed by emergent (27.5%, free-floating (12.5%, rooted-submersed (10.0%, and floating-leaved (7.5%. The lowest richness was observed at the estuarine region (3 species, and the highest richness in the upper basin (17 species. The rooted-submersed Hydrothrix gardneri Hooker f. and Ceratophyllum demersum L. were observed in great abundance and frequency in the Santa Cruz Reservoir of Apodi, especially in areas close to cage farms of Nile tilapia (Oreochromis niloticus (Linnaeus, 1758. The most common free-floating species were Eichhornia crassipes (Mart. Solms., Pistia stratiotes L., and Salvinia auriculata Aubl., predominantly in stretches that run through urban centers; CONCLUSION: The species richness of aquatic macrophytes in aquatic environments of the caatinga is similar to that observed in other basins of Brazil. Because of the many dams and reservoirs in the semi-arid Northeast, inventory and monitoring of aquatic macrophytes have become essential, especially in basins that will receive water from the diversion of the São Francisco River.OBJETIVO: Nós objetivamos avaliar a riqueza e a distribuição das macrófitas aquáticas nos ambientes aqu

  14. Hydrologic feasibility of artificial forestation in the semi-arid Loess Plateau of China

    Directory of Open Access Journals (Sweden)

    T. T. Jin

    2011-08-01

    Full Text Available Hydrologic viability, in terms of moisture availability, is fundamental to ecosystem sustainability in arid and semi-arid regions. In this study, we examine the spatial distribution and after-planting variations of soil moisture content (SMC in black locust tree (Robinia pseudoacacia L. plantings in the Loess Plateau of China at a regional scale. Thirty sites (5 to 45 yr old were selected, spanning an area of 300 km by 190 km in the northern region of the Shaanxi Province. The SMC was measured to a depth of 100 cm at intervals of 10 cm. Geographical, topographic and vegetation information was recorded, and soil organic matter was evaluated. The results show that, at the regional scale, SMC spatial variability was most highly correlated with rainfall. The negative relationship between the SMC at a depth of 20–50 cm and the stand age was stronger than at other depths, although this relationship was not significant at a 5 % level. Watershed analysis shows that the after-planting SMC variation differed depending upon precipitation. The SMC of plantings in areas receiving sufficient precipitation (e.g., mean annual precipitation (MAP of 617 mm may increase with stand age due to improvements in soil water-holding capacity and water-retention abilities after planting. For areas experiencing water shortages (e.g., MAP = 509 mm, evapotranspiration may cause planting soils to dry within the first 20 yr of growth. It is expected that, as arid and semi-arid plantings age, evapotranspiration will decrease, and the soil profile may gradually recover. In extremely dry areas (e.g., MAP = 352 mm, the variation in after-planting SMC with stand age was found to be negligible. The MAP can be used as an index to divide the study area into different ecological regions. Afforestation may sequentially exert positive, negative and negligible effects on SMCs with a decrease in the MAP. Therefore, future restoration measures should correspond to the local climate

  15. Abrupt hydroclimate disruption across the Australian arid zone 50 ka coincident with human colonization

    Science.gov (United States)

    Miller, G. H.; Fogel, M. L.; Magee, J. W.; Gagan, M. K.

    2016-12-01

    Although many studies focus on how climate change impacted ancient societies, in Australia a growing body of evidence indicates that activities of the earliest human colonizers in turn altered the Australian climate. We utilize the stable isotopes of carbon and oxygen preserved in near-continuous 100 ka time series of avian eggshell from five regions across the Australian arid zone to reconstruct ecosystem status (d13C) and effective moisture (d18O). Training sets of sub-modern samples provide the basis for the reconstructions. Together, d13C and d18O provide independent estimates of ecosystem status and climate over the past 100 ka from the same dated sample, reducing correlation uncertainties between proxies. Changes in eggshell d13C document a dramatic reduction of palatable summer-wet C4 grasses in all regions between 50 and 45 ka, that has persisted through to modern times. Continuous 100 ka records of effective moisture derived from eggshell d18O show moist conditions from 100 to 60 ka, with variable drying after 60 ka, but the strong shift toward greatest aridity is coincident with the onset of the last glacial maximum 30 ka ago, 15 ka after the observed ecosystem restructuring. Combining the d13C and d18O time-series shows that an abrupt and permanent restructuring of the moisture/ecosystem balance occurred between 50 and 45 ka. Additional studies show that most large monsoon-fed inland arid-zone lakes carried permanent water at least intermittently between 120 and 50 ka, but never experienced permanent deep-water status after 45 ka, despite a wide range of global climate states, including the early Holocene when most other monsoon systems were reinvigorated. The lack of exceptional climate shifts either locally or globally between 60 and 40 ka eliminates climate as the cause of the ecosystem restructuring and persistent lake desiccation. Collectively these data suggest the wave of human colonization across Australia in altered land surface characteristics

  16. CTD Niskin bottle data from the R/V WECOMA in the North Pacific Ocean in support of the National Science Foundation Coastal Ocean Processes program River Influences on Shelf Ecosystems (NSF CoOP RISE), cruise RISE05W3, from 20040708 to 20060613 (NODC Accession 0051411)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The CoOP RISE program was designed to determine the impact of large river discharge on coastal shelf ecosystems. Macronutrient and chlorophyll data were collected as...

  17. Net Ecosystem Carbon Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Net Ecosystem Carbon Flux is defined as the year-over-year change in Total Ecosystem Carbon Stock, or the net rate of carbon exchange between an ecosystem and the...

  18. Microbial Ecosystems, Protection of

    NARCIS (Netherlands)

    Bodelier, P.L.E.; Nelson, K.E.

    2014-01-01

    Synonyms Conservation of microbial diversity and ecosystem functions provided by microbes; Preservation of microbial diversity and ecosystem functions provided by microbes Definition The use, management, and conservation of ecosystems in order to preserve microbial diversity and functioning.

  19. Astronomical Ecosystems

    Science.gov (United States)

    Neuenschwander, D. E.; Finkenbinder, L. R.

    2004-05-01

    Just as quetzals and jaguars require specific ecological habitats to survive, so too must planets occupy a tightly constrained astronomical habitat to support life as we know it. With this theme in mind we relate the transferable features of our elementary astronomy course, "The Astronomical Basis of Life on Earth." Over the last five years, in a team-taught course that features a spring break field trip to Costa Rica, we have introduced astronomy through "astronomical ecosystems," emphasizing astronomical constraints on the prospects for life on Earth. Life requires energy, chemical elements, and long timescales, and we emphasize how cosmological, astrophysical, and geological realities, through stabilities and catastrophes, create and eliminate niches for biological life. The linkage between astronomy and biology gets immediate and personal: for example, studies in solar energy production are followed by hikes in the forest to examine the light-gathering strategies of photosynthetic organisms; a lesson on tides is conducted while standing up to our necks in one on a Pacific beach. Further linkages between astronomy and the human timescale concerns of biological diversity, cultural diversity, and environmental sustainability are natural and direct. Our experience of teaching "astronomy as habitat" strongly influences our "Astronomy 101" course in Oklahoma as well. This "inverted astrobiology" seems to transform our student's outlook, from the universe being something "out there" into something "we're in!" We thank the SNU Science Alumni support group "The Catalysts," and the SNU Quetzal Education and Research Center, San Gerardo de Dota, Costa Rica, for their support.

  20. Asynchronous glaciations in arid continental climate

    Science.gov (United States)

    Batbaatar, Jigjidsurengiin; Gillespie, Alan R.; Fink, David; Matmon, Ari; Fujioka, Toshiyuki

    2018-02-01

    Mountain glaciers at ∼26-19 ka, during the global Last Glacial Maximum near the end of the last 105 yr glacial cycle, are commonly considered on the basis of dating and field mapping in several well-studied areas to have been the largest of the late Quaternary and to have advanced synchronously from region to region. However, a numerical sensitivity model (Rupper and Roe, 2008) predicts that the fraction of ablation due to melting varies across Central Asia in proportion to the annual precipitation. The equilibrium-line altitude of glaciers across this region likely varies accordingly: in high altitude, cold and arid regions sublimation can ablate most of the ice, whereas glaciers fed by high precipitation cannot ablate completely due to sublimation alone, but extend downhill until higher temperatures there cause them to melt. We have conducted field studies and 10Be dating at five glaciated sites along a precipitation gradient in Mongolia to test the Rupper/Roe model. The sites are located in nearby 1.875 × 1.875° cells of the Rupper/Roe model, each with a different melt fraction, in this little-studied region. The modern environment of the sites ranges from dry subhumid in the north (47.7° N) to arid in the south (45° N). Our findings show that the maximum local advances in the dry subhumid conditions predated the global Last Glacial Maximum and were likely from MIS 3. However, we also found that at ∼8-7 ka a cirque glacier in one mountain range of the arid Gobi desert grew to a magnitude comparable to that of the local maximum extent. This Holocene maximum occurred during a regional pluvial period thousands of years after the retreat of the Pleistocene glaciers globally. This asynchronous behavior is not predicted by the prevailing and generally correct presumption that glacier advances are dominantly driven by temperature, although precipitation also plays a role. Our findings are consistent with and support the Rupper/Roe model, which calls for

  1. Disturbance and net ecosystem production across three climatically distinct forest landscapes

    Science.gov (United States)

    John L. Campbell; O.J. Sun; B.E. Law

    2004-01-01

    Biometric techniques were used to measure net ecosystem production (NEP) across three climatically distinct forest chronosequences in Oregon. NEP was highly negative immediately following stand-replacing disturbance in all forests and recovered to positive values by 10, 20, and 30 years of age for the mild mesic Coast Range, mesic West Cascades, and semi-arid East...

  2. The shrubland as soil and water conservation agent in mediterranean-type ecosystems

    NARCIS (Netherlands)

    Cerda, A.; Gimenez-Morera, A.; Jordan, A.; Pereira, P.; Novara, A.; Keesstra, S.D.; Mataix Solera, J.; Ruiz-Sinoga, J.A.

    2015-01-01

    John Thornes found that shrubland was a key factor in the control of soil erosion on Mediterranean hillsides. His research inspired many scientists to investigate the impact of shrubland changes and management in semi-arid ecosystems. An example of Professor Thornes’ scientific influence is the

  3. IFOAM Training Manual: Training Manual for Organic Agriculture in the Arid and Semi-arid Tropics

    OpenAIRE

    Weidmann, Gilles; Kilcher, Lukas; Garibay, Salvador V.

    2007-01-01

    The first IFOAM Training Manual for Organic Agriculture in the Tropics (the Basic Manual) was published in 2004. The Research Institute of Organic Agriculture (FiBL) together with partners of the organic movement in the Tropics were commissioned by IFOAM to complete two new training manuals that build on the Basic Manual. The new IFOAM training manuals address the two basic climatic zones of the Tropics, the Arid and Semi-Arid Tropics, and the Humid Tropics. For both new manuals, already e...

  4. Spectral Unmixing of Vegetation, Soil and Dry Carbon in Arid Regions: Comparing Multispectral and Hyperspectral Observations

    Science.gov (United States)

    Asner, Gregory P.; Heidebrecht, Kathleen B.

    2001-01-01

    Remote sensing of vegetation cover and condition is critically needed to understand the impacts of land use and climate variability in and and semi-arid regions. However, remote sensing of vegetation change in these environments is difficult for several reasons. First, individual plant canopies are typically small and do not reach the spatial scale of typical Landsat-like satellite image pixels. Second, the phenological status and subsequent dry carbon (or non-photosynthetic) fraction of plant canopies varies dramatically in both space and time throughout and and semi-arid regions. Detection of only the 'green' part of the vegetation using a metric such as the normalized difference vegetation index (NDVI) thus yields limited information on the presence and condition of plants in these ecosystems. Monitoring of both photosynthetic vegetation (PV) and non-photosynthetic vegetation (NPV) is needed to understand a range of ecosystem characteristics including vegetation presence, cover and abundance, physiological and biogeochemical functioning, drought severity, fire fuel load, disturbance events and recovery from disturbance.

  5. How Green Water Flows structure be a decision indicator for ecological water allocation in arid Ejina Delta, China.

    Science.gov (United States)

    Yu, J.; Du, C.; Zhang, Y.; Liu, X.

    2014-12-01

    Green water flows, a key ecohydrological process, dominates the hydrological cycle in arid region. The structure of green water flows reflects the landscape water consumption characteristics and can be easily obtained by means of remote sensing approach. In arid region, limited fresh water and fragile environment resulted in sharp contradictions between economy and natural ecosystem concerning water demands. To rationally allocate economic and ecological water use, to maximize the regional freshwater use efficiency, is the route one must take for sustainable development in arid area. The pursuit of the most necessary ecological protection function and the maximum ecological water use efficiency is the key to ecological water allocation. However, we are short of simple and quick detectable variables or indexes to assess ecological water allocation decision. This paper introduced the green water flows structure as a decision variable, chose Heihe river flow allocation to downstream Ejina Delta for ecological protection as an example, put forward why and how green water flows structure could be used for ecological water allocation decision. The authors expect to provide reference for integrated fresh water resources management practice in arid region.

  6. 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 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 be under a

  7. 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 ...

  8. 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/Ari...d1a.10.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Arid1a.Adipocyte.tsv http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/colo/Adipocyte.gml ...

  9. The role of fish, wildlife, and plant research in ecosystem management

    Science.gov (United States)

    Susan C. Loeb; Michael R. Lennartz; Robert C. Szaro

    1998-01-01

    This paper examines the concepts of ecology, ecosystems, and ecosystem management and then further examines the role of fish, wildlife, and plant ecology research in ecosystem management, past, present, and future. It is often assumed that research in support of ecosystem management will entail comprehensive studies of entire ecosystems, whereas research programs that...

  10. C:N:P Stoichiometry and Leaf Traits of Halophytes in an Arid Saline Environment, Northwest China

    Science.gov (United States)

    Wang, Lilong; Zhao, Guanxiang; Li, Meng; Zhang, Mingting; Zhang, Lifang; Zhang, Xinfang; An, Lizhe; Xu, Shijian

    2015-01-01

    Salinization is an important and increasingly prevalent issue which has broad and profound effects on plant survival and distribution pattern. To understand the patterns and potential drivers of leaf traits in saline environments, we determined the soil properties, leaf morphological traits (specific leaf area, SLA, and leaf dry matter content, LDMC), leaf chemical traits (leaf carbon, C, nitrogen, N, and phosphorus, P, stoichiometry) based on 142 observations collected from 23 sites in an arid saline environment, which is a vulnerable ecosystem in northwest China. We also explored the relationships among leaf traits, the responses of leaf traits, and plant functional groups (herb, woody, and succulent woody) to various saline environments. The arid desert halophytes were characterized by lower leaf C and SLA levels, higher N, but stable P and N:P. The leaf morphological traits were correlated significantly with the C, N, and P contents across all observations, but they differed within each functional group. Succulent woody plants had the lowest leaf C and highest leaf N levels among the three functional groups. The growth of halophytes might be more limited by N rather than P in the study area. GLM analysis demonstrated that the soil available nutrients and plant functional groups, but not salinity, were potential drivers of leaf C:N:P stoichiometry in halophytes, whereas species differences accounted for the largest contributions to leaf morphological variations. Our study provides baseline information to facilitate the management and restoration of arid saline desert ecosystem. PMID:25798853

  11. Integrated assessment of policy interventions for promoting sustainable irrigation in semi-arid environments: a hydro-economic modeling approach.

    Science.gov (United States)

    Blanco-Gutiérrez, Irene; Varela-Ortega, Consuelo; Purkey, David R

    2013-10-15

    Sustaining irrigated agriculture to meet food production needs while maintaining aquatic ecosystems is at the heart of many policy debates in various parts of the world, especially in arid and semi-arid areas. Researchers and practitioners are increasingly calling for integrated approaches, and policy-makers are progressively supporting the inclusion of ecological and social aspects in water management programs. This paper contributes to this policy debate by providing an integrated economic-hydrologic modeling framework that captures the socio-economic and environmental effects of various policy initiatives and climate variability. This modeling integration includes a risk-based economic optimization model and a hydrologic water management simulation model that have been specified for the Middle Guadiana basin, a vulnerable drought-prone agro-ecological area with highly regulated river systems in southwest Spain. Namely, two key water policy interventions were investigated: the implementation of minimum environmental flows (supported by the European Water Framework Directive, EU WFD), and a reduction in the legal amount of water delivered for irrigation (planned measure included in the new Guadiana River Basin Management Plan, GRBMP, still under discussion). Results indicate that current patterns of excessive water use for irrigation in the basin may put environmental flow demands at risk, jeopardizing the WFD's goal of restoring the 'good ecological status' of water bodies by 2015. Conflicts between environmental and agricultural water uses will be stressed during prolonged dry episodes, and particularly in summer low-flow periods, when there is an important increase of crop irrigation water requirements. Securing minimum stream flows would entail a substantial reduction in irrigation water use for rice cultivation, which might affect the profitability and economic viability of small rice-growing farms located upstream in the river. The new GRBMP could contribute

  12. Ecosystem engineering effects on species diversity across ecosystems: a meta-analysis.

    Science.gov (United States)

    Romero, Gustavo Q; Gonçalves-Souza, Thiago; Vieira, Camila; Koricheva, Julia

    2015-08-01

    Ecosystem engineering is increasingly recognized as a relevant ecological driver of diversity and community composition. Although engineering impacts on the biota can vary from negative to positive, and from trivial to enormous, patterns and causes of variation in the magnitude of engineering effects across ecosystems and engineer types remain largely unknown. To elucidate the above patterns, we conducted a meta-analysis of 122 studies which explored effects of animal ecosystem engineers on species richness of other organisms in the community. The analysis revealed that the overall effect of ecosystem engineers on diversity is positive and corresponds to a 25% increase in species richness, indicating that ecosystem engineering is a facilitative process globally. Engineering effects were stronger in the tropics than at higher latitudes, likely because new or modified habitats provided by engineers in the tropics may help minimize competition and predation pressures on resident species. Within aquatic environments, engineering impacts were stronger in marine ecosystems (rocky shores) than in streams. In terrestrial ecosystems, engineers displayed stronger positive effects in arid environments (e.g. deserts). Ecosystem engineers that create new habitats or microhabitats had stronger effects than those that modify habitats or cause bioturbation. Invertebrate engineers and those with lower engineering persistence (1 year. Invertebrate species richness was particularly responsive to engineering impacts. This study is the first attempt to build an integrative framework of engineering effects on species diversity; it highlights the importance of considering latitude, habitat, engineering functional group, taxon and persistence of their effects in future theoretical and empirical studies. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

  13. Hydropedological interpretation of arid soilscapes, South Africa

    Science.gov (United States)

    Tinnefeld, Martin; Van Tol, Jacobus; Le Roux, Pieter

    2017-04-01

    Hydropedological investigations in arid regions are scarce due to the low the low contribution of these areas to water resources. Infrequent rainfall and few flow events also complicates measurements hydrological studies. Hydropedological studies, relating soil morphological properties and their spatial distribution to hydrological response, have been studied in detail in semi-arid, temperate, and sub-humid regions. In this paper, we investigated the relation between soil morphological properties and selected hydrological properties of soils in an arid landscape. We also studied the spatial distribution of the morphological properties to conceptualise the hydrological behaviour of different soilscapes in the area. A total of 806 soil profiles, covering an area of 4836 ha in the Northern Cape Province of South Africa were described and classified. The geology is dominated by Dwyka tillite overlain by aeolian sands with scattered Dolerite buttes. Thirteen modal profiles, representing the dominant soils types were selected, sampled at horizon level, and analysed for pH, CEC, iron, manganese, carbonate content. In situ measurements of saturated and near saturated (tension) hydraulic conductivity (Ks) were conducted to determine the water conducting macroporosity (WCM). Undisturbed cores were collected on which water retention characteristics were determined under laboratory conditions. Results indicate that dry soil colour, degree of structure development and the presence, absence, and abundance of carbonates as well as the degree of precipitation, are important indicators of hydrological response. For example; grey soils typically have lower Ks with higher storage capacity than soils dominated by red colours, whereas abundant carbonate precipitations in the soil matrix have lower WCM due to clogging of macropores. The dominant soil distribution pattern indicates that rapid vertical flow, through and out of the pedon, might contribute to recharge of an accumulative

  14. Predicting the future impact of droughts on ungulate populations in arid and semi-arid environments.

    Directory of Open Access Journals (Sweden)

    Clare Duncan

    Full Text Available Droughts can have a severe impact on the dynamics of animal populations, particularly in semi-arid and arid environments where herbivore populations are strongly limited by resource availability. Increased drought intensity under projected climate change scenarios can be expected to reduce the viability of such populations, yet this impact has seldom been quantified. In this study, we aim to fill this gap and assess how the predicted worsening of droughts over the 21(st century is likely to impact the population dynamics of twelve ungulate species occurring in arid and semi-arid habitats. Our results provide support to the hypotheses that more sedentary, grazing and mixed feeding species will be put at high risk from future increases in drought intensity, suggesting that management intervention under these conditions should be targeted towards species possessing these traits. Predictive population models for all sedentary, grazing or mixed feeding species in our study show that their probability of extinction dramatically increases under future emissions scenarios, and that this extinction risk is greater for smaller populations than larger ones. Our study highlights the importance of quantifying the current and future impacts of increasing extreme natural events on populations and species in order to improve our ability to mitigate predicted biodiversity loss under climate change.

  15. Predicting the future impact of droughts on ungulate populations in arid and semi-arid environments.

    Science.gov (United States)

    Duncan, Clare; Chauvenet, Aliénor L M; McRae, Louise M; Pettorelli, Nathalie

    2012-01-01

    Droughts can have a severe impact on the dynamics of animal populations, particularly in semi-arid and arid environments where herbivore populations are strongly limited by resource availability. Increased drought intensity under projected climate change scenarios can be expected to reduce the viability of such populations, yet this impact has seldom been quantified. In this study, we aim to fill this gap and assess how the predicted worsening of droughts over the 21(st) century is likely to impact the population dynamics of twelve ungulate species occurring in arid and semi-arid habitats. Our results provide support to the hypotheses that more sedentary, grazing and mixed feeding species will be put at high risk from future increases in drought intensity, suggesting that management intervention under these conditions should be targeted towards species possessing these traits. Predictive population models for all sedentary, grazing or mixed feeding species in our study show that their probability of extinction dramatically increases under future emissions scenarios, and that this extinction risk is greater for smaller populations than larger ones. Our study highlights the importance of quantifying the current and future impacts of increasing extreme natural events on populations and species in order to improve our ability to mitigate predicted biodiversity loss under climate change.

  16. Pattern Water Use Efficiency perspective on degradation and recovery of shrublands across Mediterranean to Arid transition zones

    Science.gov (United States)

    Shoshany, Maxim

    2017-04-01

    Shrublands cover a total of 12.7 million km2 , a considerable part of them along semi-arid to arid transition zones. Varying patterns of shrubs, grasses and barren land along such climatic gradients express the spatial dimension of climate change and human disturbance which attracted limited attention in the eco-geomorphic literature. Questions concerning relationships between rainfall, shrublands biomass and their patterns are fundamental for the understanding of these ecosystems response to the expected changes in water availability due to global warming and the increase in human disturbance to natural ecosystems following World population growth. While processes leading to the formation of patterns had attracted considerable attention, the spatial dimension of Water Use Efficiency (WUE) which is a parameter measuring ecosystems productivity in relation to water availability is severely missing. Relative shrub cover is a primary estimator of the fraction of water utilized for shrubs growth. Edge effects must be considered as well in fragmented ecosystems in general and in hot regions in particular since soil temperature in hot regions which frequently exceed 50oC during summer months decreases photosynthesis and productivity in plants bordering bare soil. This edge effect is decreasing with the increase in shrubs' height. Pattern Water Use Efficiency describes the combined effect of shrub cover, shrub height and shrub patches edge zone proportion on water use efficiency. In my presentation I will first present mapping od PWUEs across Mediterranean to arid transition zones in the Eastern Mediterranean. Then I will present several mathematical models describing PWUE for simulated patterns, searching for the spatial parameterization providing the highest sensitivity to patterns responses to changes in habitat conditions. Such simulations would allow us to discuss several PWUE strategies for shrublands recovery under the current scenarios of climate change and human

  17. Ecosystem extent and fragmentation

    Science.gov (United States)

    Sayre, Roger; Hansen, Matt

    2017-01-01

    One of the candidate essential biodiversity variable (EBV) groups described in the seminal paper by Pereira et al. (2014) concerns Ecosystem Structure. This EBV group is distinguished from another EBV group which encompasses aspects of Ecosystem Function. While the Ecosystem Function EBV treats ecosystem processes like nutrient cycling, primary production, trophic interactions, etc., the Ecosystem Structure EBV relates to the set of biophysical properties of ecosystems that create biophysical environmental context, confer biophysical structure, and occur geographically. The Ecosystem Extent and Fragmentation EBV is one of the EBVs in the Ecosystem Structure EBV group.Ecosystems are understood to exist at multiple scales, from very large areas (macro-ecosystems) like the Arctic tundra, for example, to something as small as a tree in an Amazonian rain forest. As such, ecosystems occupy space and therefore can be mapped across any geography of interest, whether that area of interest be a site, a nation, a region, a continent, or the planet. One of the most obvious and seemingly straightforward EBVs is Ecosystem Extent and Fragmentation. Ecosystem extent refers to the location and geographic distribution of ecosystems across landscapes or in the oceans, while ecosystem fragmentation refers to the spatial pattern and connectivity of ecosystem occurrences on the landscape.

  18. Future aridity under conditions of global climate change

    Science.gov (United States)

    Asadi Zarch, Mohammad Amin; Sivakumar, Bellie; Malekinezhad, Hossein; Sharma, Ashish

    2017-11-01

    Global climate change is anticipated to cause some major changes in hydroclimatic conditions around the world. As aridity is a reliable indicator of potential available water, assessment of its changes under future climatic conditions is important for proper management of water. This study employs the UNESCO aridity/humidity index, which is a derivative of precipitation (P) and potential evapotranspiration (PET), for assessment of aridity. Historical (1901-2005) simulations and future (2006-2100) projections of 22 global climate models (GCMs) from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) are studied. The Nested Bias Correction (NBC) approach is used to correct possible biases of precipitation (simulated directly by the GCMs) and PET (estimated by applying FAO56-Penman-Monteith model on simulated parameters of the GCMs). To detect future aridity changes, the areal extents of the aridity zones in the past and future periods as well as through four sub-periods (2006-2025, 2026-2050, 2051-2075, and 2076-2100) of the future are compared. The results indicate that changes in climate will alter the areal extents of aridity zones in the future. In general, from the first sub-period towards the last one, the area covered by hyper-arid, arid, semi-arid, and sub-humid zones will increase (by 7.46%, 7.01%, 5.80%, and 2.78%, respectively), while the area of the humid regions will decrease (by 4.76%), suggesting that there will be less water over the global land area in the future. To understand the cause of these changes, precipitation and PET are also separately assumed to be stationary throughout the four future sub-periods and the resulting aridity changes are then analyzed. The results reveal that the aridity changes are mostly caused by the positive PET trends, even though the slight precipitation increase lessens the magnitude of the changes.

  19. A decade of irrigation transforms the soil microbiome of a semi-arid pine forest.

    Science.gov (United States)

    Hartmann, Martin; Brunner, Ivano; Hagedorn, Frank; Bardgett, Richard D; Stierli, Beat; Herzog, Claude; Chen, Xiamei; Zingg, Andreas; Graf-Pannatier, Elisabeth; Rigling, Andreas; Frey, Beat

    2017-02-01

    The impact of climate change on the soil microbiome potentially alters the biogeochemical cycle of terrestrial ecosystems. In semi-arid environments, water availability is a major constraint on biogeochemical cycles due to the combination of high summer temperatures and low rainfall. Here, we explored how 10 years of irrigation of a water-limited pine forest in the central European Alps altered the soil microbiome and associated ecosystem functioning. A decade of irrigation stimulated tree growth, resulting in higher crown cover, larger yearly increments of tree biomass, increased litter fall and greater root biomass. Greater amounts of plant-derived inputs associated with increased primary production in the irrigated forest stands stimulated soil microbial activity coupled with pronounced shifts in the microbiome from largely oligotrophic to more copiotrophic lifestyles. Microbial groups benefitting from increased resource availabilities (litter, rhizodeposits) thrived under irrigation, leading to enhanced soil organic matter mineralization and carbon respired from irrigated soils. This unique long-term study provides new insights into the impact of precipitation changes on the soil microbiome and associated ecosystem functioning in a water-limited pine forest ecosystem and improves our understanding of the persistency of long-term soil carbon stocks in a changing climate. © 2016 John Wiley & Sons Ltd.

  20. New species and records of Anacroneuria (Plecoptera: Perlidae) from the northeastern semi-arid region of Brazil.

    Science.gov (United States)

    Duarte, Tácio; Lecci, Lucas Silveira

    2016-02-11

    The genus Anacroneuria is widely distributed in the Neotropical Region. There are about 80 species listed from Brazil, five of which are recorded from the northeastern semi-arid region of Brazil, an area characterized by irregular and low precipitation. Examination of adult Anacroneuria material from this including areas of Caatinga desert vegetation and Atlantic forest revealed two new species records, A. debilis (Pictet) and A. terere Righi-Cavallaro & Lecci. Additionally, two new species, A. calori n. sp. and A. singela n. sp., are described from this material. These new records and new species reflect a major effort to document the biodiversity of the aquatic insects of the northeastern semi-arid region of Brazil by the Research Program in Semi-arid Biodiversity.

  1. Organic carbon organic matter and bulk density relationships in arid ...

    African Journals Online (AJOL)

    Evaluation of their stocks requires knowledge about BD. BD is affected by factors such as water, aeration status, root penetrate, clay content, texture, land use and management, therefore it is a very important soil parameter. Key words: Soil organic carbon, soil organic matter, soil bulk density, arid-semi arid soils.

  2. optimization of water resources allocation in semi-arid region

    African Journals Online (AJOL)

    Eng Obi Ibeje

    Semi-arid regions are characterized by long, dry seasons and short mild wet seasons. They face periods of water shortages due to high demand and inconsistent supply. Water allocation is often the primary tool of water managers in semi- arid regions (Haten–Moussallen et al, 1999). “Water allocation is a means of dividing ...

  3. Modelling annual evapotranspiration in a semi-arid, African savanna ...

    African Journals Online (AJOL)

    Modelling annual evapotranspiration in a semi-arid, African savanna: functional convergence theory, MODIS LAI and the Penman–Monteith equation. ... and, when used independently of the eddy covariance data, ETMODIS predicted an annual ET of 378 mm in 2007 for the semi-arid savanna around the Skukuza flux site.

  4. 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)

  5. International Arid Lands Consortium's contributions to Madrean Archipelago stewardship

    Science.gov (United States)

    Peter F. Ffolliott; Jeffery O. Dawson; Itshack Moshe; Timothy E. Fulbright; E. Carter Johnson; Paul Verburg; Muhannad Shatanawi; Donald F. Caccamise; Jim P. M. Chamie

    2005-01-01

    The International Arid Lands Consortium (IALC) was established in 1990 to promote research, education, and training activities related to the development, management, and reclamation of arid and semiarid lands worldwide. Building on a decade of experience, the IALC continues to increase the knowledge base for managers by funding research, development, and demonstration...

  6. Abiotic and herbaceous vegetational characteristics of an arid ...

    African Journals Online (AJOL)

    On the whole, herbaceous vegetation production and productivity were episodic in nature and closely linked to rainfall. The high primary productivity puts arid and semi-arid rangelands under sharp focus as CO2 sinks, whose role in the amelioration of greenhouse effect could be more important than is currently appreciated.

  7. Performance evaluation of constructed wetlands: A review of arid ...

    African Journals Online (AJOL)

    Aiming at environmental pollution control through the use of constructed wetlands systems (CWs) in arid and semi arid climatic region, a detailed review of CWs was undertaken. Given the practical application and simplicity of the technology, principles for building phytotechnology-ecohydrology environment used for ...

  8. Vegetation pattern formation in semi-arid grazing systems

    NARCIS (Netherlands)

    HillerisLambers, R.; Rietkerk, M.G.; Bosch, F. van den; Prins, H.H.T.; Kroon, H. de

    2001-01-01

    Hypotheses about the origin of vegetation pattern formation in semi-arid areas around the world almost all include a common feature of semi-arid areas: the presence of a positive feedback between plant density and water infiltration. We investigate whether this positive feedback and the spatial

  9. Watershed Management in Arid Zones: A Prototype Short Course.

    Science.gov (United States)

    Thames, John L., Ed.; Fischer, John N., Ed.

    Presented is information recommended for inclusion in a short course to help extend knowledge of water resource development and research techniques in arid and semi-arid regions. Information is particularly intended for applicability in developing nations. Included are considerations of livestock grazing, use of hydrologic data, vegetation…

  10. Multilayer perceptron neural network for downscaling rainfall in arid ...

    Indian Academy of Sciences (India)

    Multilayer perceptron neural network for downscaling rainfall in arid region: A case study of Baluchistan, Pakistan ... A multilayer perceptron (MLP) neural network has been proposed in the present study for the downscaling of rainfall in the data scarce arid region of Baluchistan province of Pakistan, which is considered as ...

  11. Arid Green Infrastructure for Water Control and Conservation ...

    Science.gov (United States)

    Green infrastructure is an approach to managing wet weather flows using systems and practices that mimic natural processes. It is designed to manage stormwater as close to its source as possible and protect the quality of receiving waters. Although most green infrastructure practices were first developed in temperate climates, green infrastructure also can be a cost-effective approach to stormwater management and water conservation in arid and semi-arid regions, such as those found in the western and southwestern United States. Green infrastructure practices can be applied at the site, neighborhood and watershed scales. In addition to water management and conservation, implementing green infrastructure confers many social and economic benefits and can address issues of environmental justice. The U.S. Environmental Protection Agency (EPA) commissioned a literature review to identify the state-of-the science practices dealing with water control and conservation in arid and semi-arid regions, with emphasis on these regions in the United States. The search focused on stormwater control measures or practices that slow, capture, treat, infiltrate and/or store runoff at its source (i.e., green infrastructure). The material in Chapters 1 through 3 provides background to EPA’s current activities related to the application of green infrastructure practices in arid and semi-arid regions. An introduction to the topic of green infrastructure in arid and semi-arid regions i

  12. Review on the Application of Ecosystem Models in Biodiversity ...

    African Journals Online (AJOL)

    This paper is an exposition with the sole aim of highlighting the relevance of ecosystem models in the analyses of biodiversity. The structure of ecosystem models enables researchers to design and consequently formulate monitoring programs that will be useful to the conservation of biodiversity. Ecosystem theoretical ...

  13. Increased water use efficiency does not prevent growth decline of Pinus canariensis in a semi-arid treeline ecotone in Tenerife, Canary Islands (Spain).

    Science.gov (United States)

    Brito, Patricia; Grams, Thorsten E E; Matysssek, Rainer; Jimenez, Maria S; Gonzalez-Rodríguez, Agueda M; Oberhuber, Walter; Wieser, Gerhard

    2016-09-01

    Intrinsic water-use efficiency of Pinus canariensis (Sweet ex Spreng.) growing at a semi-arid treeline has increased during the past 37 years. Tree-ring width by contrast has declined, likely caused by reduced stomatal conductance due to increasing aridity. Rising atmospheric CO2 concentration (Ca ) has been related to tree growth enhancement accompanied by increasing intrinsic water-use-efficiency (iWUE). Nevertheless, the extent of rising Ca on long-term changes in iWUE and growth has remained poorly understood to date in Mediterranean treeline ecosystems. This study aimed to examine radial growth and physiological responses of P. canariensis in relation to rising Ca and increasing aridity at treeline in Tenerife, Canary Islands, Spain. We evaluated temporal changes in secondary growth (tree-ring width; TRW) and tree ring stable C isotope signature for assessing iWUE from 1975 through 2011. Precipitation was the main factor controlling secondary growth. Over the last 36 years P. canariensis showed a decline in TRW at enhanced iWUE, likely caused by reduced stomatal conductance due to increasing aridity. Our results indicate that increasing aridity has overridden the potential CO2 fertilization on tree growth of P. canariensis at its upper distribution limit.

  14. Transformation of Digital Ecosystems

    DEFF Research Database (Denmark)

    Henningsson, Stefan; Hedman, Jonas

    2014-01-01

    the Digital Ecosystem Technology Transformation (DETT) framework for explaining technology-based transformation of digital ecosystems by integrating theories of business and technology ecosystems. The framework depicts ecosystem transformation as distributed and emergent from micro-, meso-, and macro- level...... coopetition. The DETT framework consists an alternative to the existing explanations of digital ecosystem transformation as the rational management of one central actor balancing ecosystem tensions. We illustrate the use of the framework by a case study of transformation in the digital payment ecosystem......In digital ecosystems, the fusion relation between business and technology means that the decision of technical compatibility of the offering is also the decision of how to position the firm relative to the coopetive relations that characterize business ecosystems. In this article we develop...

  15. Assessment of Dry Wells for Stormwater Capture and Aquifer Recharge in the Arid and Semi-Arid Southwest

    Science.gov (United States)

    GOAL: to evaluate the utility of innovative, distributed, low impact development (LID) infrastructure and best management practices (BMPs) for wet weather capture and drinking water aquifer recharge in the arid and semi-arid southwestern USA OBJECTIVES: Design, build, monitor t...

  16. A decision support approach for the selection and implementation of water harvesting techniques in arid and semi-arid regions

    NARCIS (Netherlands)

    Grum, Berhane; Hessel, Rudi; Kessler, Aad; Woldearegay, Kifle; Yazew, Eyasu; Ritsema, Coen; Geissen, Violette

    2016-01-01

    Water harvesting techniques (WHTs) improve the availability of water, which is essential for growing crops, especially in arid and semi-arid areas. A decision support approach can help in the selection of WHTs suitable under site-specific bio-physical and socio-economic conditions. This paper

  17. Identification of suitabel sites for rainwater harvesting structures in arid and semi-arid regions: A review

    NARCIS (Netherlands)

    Ali, A.A.; Riksen, M.J.P.M.; Ouessar, M.; Ritsema, C.J.

    2016-01-01

    Harvested rainwater is an alternative source of water in arid and semi-arid regions (ASARs) around the world. Many researchers have developed and applied various methodologies and criteria to identify suitable sites and techniques for rainwater harvesting (RWH). Determining the best method or

  18. Plant diversity and ecosystem multifunctionality peak at intermediate levels of woody cover in global drylands

    Science.gov (United States)

    Soliveres, Santiago; Maestre, Fernando T.; Eldridge, David J.; Delgado-Baquerizo, Manuel; Quero, José Luis; Bowker, Matthew A.; Gallardo, Antonio

    2015-01-01

    Aim The global spread of woody plants into grasslands is predicted to increase over the coming century. While there is general agreement regarding the anthropogenic causes of this phenomenon, its ecological consequences are less certain. We analyzed how woody vegetation of differing cover affects plant diversity (richness and evenness) and multiple ecosystem functions (multifunctionality) in global drylands, and how this changes with aridity. Location 224 dryland sites from all continents except Antarctica widely differing in their environmental conditions (from arid to dry-subhumid sites) and woody covers (from 0 to 100%). Methods Using a standardized field survey, we measured the cover, richness and evenness of perennial vegetation. At each site, we measured 14 ecosystem functions related to soil fertility and the build-up of nutrient pools. These functions are critical for maintaining ecosystem function in drylands. Results Species richness and ecosystem multifunctionality were strongly influenced by woody vegetation, with both variables peaking at relative woody covers (RWC) of 41-60%. This relationship shifted with aridity. We observed linear positive effects of RWC in dry-subhumid sites. These positive trends shifted to hump-shaped RWC-diversity and multifunctionality relationships under semiarid environments. Finally, hump-shaped (richness, evenness) or linear negative (multifunctionality) effects of RWC were found under the most arid conditions. Main conclusions Plant diversity and multifunctionality peaked at intermediate levels of woody cover, although this relationship became increasingly positive under wetter environments. This comprehensive study accounts for multiple ecosystem attributes across a range of woody covers and environmental conditions. Our results help us to reconcile contrasting views of woody encroachment found in current literature and can be used to improve predictions of the likely effects of encroachment on biodiversity and ecosystem

  19. Valuation of rangeland ecosystem services

    Science.gov (United States)

    Gascoigne, W.R.

    2011-01-01

    into analyzing the costs and benefits associated with policies being proposed, or possibly already implemented. For example, with monetized values acting as a common metric, one could compare the 'benefits' of converting a rangeland ecosystem for commercial development (perhaps estimated at the market value of the developed land) with the foregone ecosystem service values (in addition to any land income lost) resulting from that land conversion. Similarly, ecosystem service values can be used to determine the level of return on an investment. rhis is a primary objective for private land conservation organizations who typically have very limited resources. Ecosystem service valuation can also have a role in damage assessments from incidents that require compensation such as oil spills. Additionally, valuation can be very informative when investigating regulatory programs that trade ecological assets such as wetland mitigation programs. Typically these programs are based simply on an 'acre for acre' criterion, and do not take into consideration varying welfare values associated with that ecosystem. Lastly, and most fundamental, ecosystem service valuation serves as a recognition tool for people of all backgrounds. Identifying and valuing ecosystem goods and services on rangelands brings to light the value these natural assets have to human welfare that often remain hidden do to their public and non-market attributes. This type of recognition is vital to the preservation of rangeland ecosystems in the future and the many ecological benefits they provide.

  20. Effects of disturbance on ecosystem dynamics of tundra and riparian vegetation: A project in the R4D program. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, J.F.

    1995-12-31

    Models were proposed as research tools to test the basic understanding of the structure and function of arctic ecosystems, as a means for providing initial management assessments of potential response to energy-related development, and as a vehicle for extrapolation of research results to other arctic sites and landscapes. This final summary report reviews progress made on models at a variety of scales from nutrient uptake by individual roots to nutrient availability within arctic landscapes, and examines potentials and critical limitations of these models for providing insight on patch and landscape level function in tundra regions.

  1. Plants reverse warming effect on ecosystem water balance.

    Science.gov (United States)

    Zavaleta, Erika S; Thomas, Brian D; Chiariello, Nona R; Asner, Gregory P; Shaw, M Rebecca; Field, Christopher B

    2003-08-19

    Models predict that global warming may increase aridity in water-limited ecosystems by accelerating evapotranspiration. We show that interactions between warming and the dominant biota in a grassland ecosystem produced the reverse effect. In a 2-year field experiment, simulated warming increased spring soil moisture by 5-10% under both ambient and elevated CO2. Warming also accelerated the decline of canopy greenness (normalized difference vegetation index) each spring by 11-17% by inducing earlier plant senescence. Lower transpirational water losses resulting from this earlier senescence provide a mechanism for the unexpected rise in soil moisture. Our findings illustrate the potential for organism-environment interactions to modify the direction as well as the magnitude of global change effects on ecosystem functioning.

  2. 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.

  3. Use of composts in revegetating arid lands

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, C.A.; Hendrickson, P.L.

    1991-09-01

    Compost has been suggested as a soil amendment for arid lands at the US Department of Energy's Hanford Site in southeastern Washington State. The operating contractor of the site, Westinghouse Hanford Company, requested that the Pacific Northwest Laboratory conduct a literature review to compile additional information on the use of compost amendments and their benefits. This report provides background information on the factors needed for plant growth and the consequences of severe soil disturbance. This report also discussed the characteristics of composts relative to other amendments and how they each affect plant growth. Finally,regulatory requirements that could affect land application of sludge-based compost on the Hanford Site are reviewed.

  4. Combined effects of climate and land management on watershed vegetation dynamics in an arid environment.

    Science.gov (United States)

    Liu, Peilong; Hao, Lu; Pan, Cen; Zhou, Decheng; Liu, Yongqiang; Sun, Ge

    2017-07-01

    Leaf area index (LAI) is a key parameter to characterize vegetation dynamics and ecosystem structure that determines the ecosystem functions and services such as clean water supply and carbon sequestration in a watershed. However, linking LAI dynamics and environmental controls (i.e., coupling biosphere, atmosphere, and anthroposphere) remains challenging and such type of studies have rarely been done at a watershed scale due to data availability. The present study examined the spatial and temporal variations of LAI for five ecosystem types within a watershed with a complex topography in the Upper Heihe River Basin, a major inland river in the arid and semi-arid western China. We integrated remote sensing-based GLASS (Global Land Surface Satellite) LAI products, interpolated climate data, watershed characteristics, and land management records for the period of 2001-2012. We determined the relationships among LAI, topography, air temperature and precipitation, and grazing history by five ecosystem types using several advanced statistical methods. We show that long-term mean LAI distribution had an obvious vertical pattern as controlled by precipitation and temperature in a hilly watershed. Overall, watershed-wide mean LAI had an increasing trend overtime for all ecosystem types during 2001-2012, presumably as a result of global warming and a wetting climate. However, the fluctuations of observed LAI at a pixel scale (1km) varied greatly across the watershed. We classified the vegetation changes within the watershed as 'Improved', 'Stabilized', and 'Degraded' according their respective LAI changes. We found that climate was not the only driver for temporal vegetation changes for all land cover types. Grazing partially contributed to the decline of LAI in some areas and masked the positive climate warming effects in other areas. Extreme weathers such as cold spells and droughts could substantially affect inter-annual variability of LAI dynamics. We concluded that

  5. Measuring Entrepreneurial Ecosystems

    NARCIS (Netherlands)

    Stam, F.C.

    How can entrepreneurial ecosystems and productive entrepreneurship can be traced empirically and how is entrepreneurship related to entrepreneurial ecosystems. The analyses in this chapter show the value of taking a systems view on the context of entrepreneurship. We measure entrepreneurial

  6. Coral reefs - Specialized ecosystems

    Digital Repository Service at National Institute of Oceanography (India)

    Wafar, M.V.M.

    This paper discusses briefly some aspects that characterize and differentiate coral reef ecosystems from other tropical marine ecosystems. A brief account on the resources that are extractable from coral reefs, their susceptibility to natural...

  7. Mapping cultural ecosystem services:

    DEFF Research Database (Denmark)

    Paracchini, Maria Luisa; Zulian, Grazia; Kopperoinen, Leena

    2014-01-01

    Research on ecosystem services mapping and valuing has increased significantly in recent years. However, compared to provisioning and regulating services, cultural ecosystem services have not yet been fully integrated into operational frameworks. One reason for this is that transdisciplinarity...

  8. FWS Ecosystem Regions

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Digital ecosystem information portraying the location and boundaries of the ecosystems. The Service originally chose the U.S. Geological Survey's Hydrologic Unit Map...

  9. Drivers of inter-annual variability in Net Ecosystem Exchange in a semi-arid savanna ecosystem, South Africa

    CSIR Research Space (South Africa)

    Archibald, SA

    2009-01-01

    Full Text Available primarily for temperate flux sites. They furthermore do not take into account the decrease in respiration at high soil temperatures. An artificial neural network (ANN) model incorporating these features predicted measured fluxes accurately (MAE 0.42 gC/m2...

  10. Trace Metals in Groundwater and Vadose Zone Calcite: In Situ Containment and Stabilization of Stronthium-90 and Other Divalent Metals and Radionuclides at Arid Western DOE Sites: Final Report for Award Number DE-FG07-02ER63486 to the University of Idaho (RW Smith) Environmental Management Science Program Project Number 87016

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Robert W.; Fujita, Yoshiko

    2007-11-07

    Radionuclide and metal contaminants are present in the vadose zone and groundwater throughout the U.S. Department of Energy (DOE) energy research and weapons complex. In situ containment and stabilization of these contaminants represents a cost-effective treatment strategy that minimizes workers’ exposure to hazardous substances, does not require removal or transport of contaminants, and generally does not generate a secondary waste stream. We have investigated an in situ bioremediation approach that immobilizes radionuclides or contaminant metals (e.g., strontium-90) by their microbially facilitated co-precipitation with calcium carbonate in groundwater and vadose zone systems. Calcite, a common mineral in many aquifers and vadose zones in the arid west, can incorporate divalent metals such as strontium, cadmium, lead, and cobalt into its crystal structure by the formation of a solid solution. Collaborative research undertaken by the Idaho National Laboratory (INL), University of Idaho, and University of Toronto as part of this Environmental Management Science Program project has focused on in situ microbially-catalyzed urea hydrolysis, which results in an increase in pH, carbonate alkalinity, ammonium, calcite precipitation, and co-precipitation of divalent cations. In calcite-saturated aquifers, microbially facilitated co-precipitation with calcium carbonate represents a potential long-term contaminant sequestration mechanism. Key results of the project include: **Demonstrating the linkage between urea hydrolysis and calcite precipitation in field and laboratory experiments **Observing strontium incorporation into calcite precipitate by urea hydrolyzers with higher distribution coefficient than in abiotic **Developing and applying molecular methods for characterizing microbial urease activity in groundwater including a quantitative PCR method for enumerating ureolytic bacteria **Applying the suite of developed molecular methods to assess the feasibility of the

  11. Global Ecosystem Restoration Index

    DEFF Research Database (Denmark)

    Fernandez, Miguel; Garcia, Monica; Fernandez, Nestor

    2015-01-01

    The Global ecosystem restoration index (GERI) is a composite index that integrates structural and functional aspects of the ecosystem restoration process. These elements are evaluated through a window that looks into a baseline for degraded ecosystems with the objective to assess restoration...

  12. Ecosystem classification, Chapter 2

    Science.gov (United States)

    M.J. Robin-Abbott; L.H. Pardo

    2011-01-01

    The ecosystem classification in this report is based on the ecoregions developed through the Commission for Environmental Cooperation (CEC) for North America (CEC 1997). Only ecosystems that occur in the United States are included. CEC ecoregions are described, with slight modifications, below (CEC 1997) and shown in Figures 2.1 and 2.2. We chose this ecosystem...

  13. Towards ecosystem accounting

    NARCIS (Netherlands)

    Duku, C.; Rathjens, H.; Zwart, S.J.; Hein, L.

    2015-01-01

    Ecosystem accounting is an emerging field that aims to provide a consistent approach to analysing environment-economy interactions. One of the specific features of ecosystem accounting is the distinction between the capacity and the flow of ecosystem services. Ecohydrological modelling to support

  14. Rights to ecosystem services

    NARCIS (Netherlands)

    Davidson, M.

    2014-01-01

    Ecosystem services are the benefits people obtain from ecosystems. Many of these services are provided outside the borders of the land where they are produced; this article investigates who is entitled to these non-excludable ecosystem services from two libertarian perspectives. Taking a

  15. Effects of fishing technique on assessing species composition in aquatic systems in semi-arid Brazil

    Directory of Open Access Journals (Sweden)

    ESF Medeiros

    Full Text Available In most ecological field research, appropriate sampling is critical for the understanding of processes underlying fish populations and communities, and is even more important in heterogeneous environments such as the aquatic systems of the semi-arid region of Brazil. This study intends to make a contribution to the development of sampling programs and gear selection in aquatic systems of semi-arid Brazil by evaluating the effects of different fishing techniques on the assessment of richness and composition of the fish fauna in selected aquatic environments. Six sites were selected to represent typical artificial (reservoirs and natural (intermittent streams environments and four different types of sampling gear were applied to each site during four occasions. The present study shows that when selecting sampling techniques to be used in aquatic systems in semi-arid Brazil, one must consider the objectives of the study, e.g. ecological or taxonomic, in order to decide on inclusion of rare species in the sampling population. Also, the effect of the sampling gear on natural abundances of fish must be considered given that some sampling techniques are highly detrimental to fish population numbers.

  16. Sensitivity of grassland productivity to aridity controlled by stomatal and xylem regulation

    Science.gov (United States)

    Konings, A. G.; Williams, A. P.; Gentine, P.

    2017-03-01

    The terrestrial water and carbon cycles are coupled through plant regulation of stomatal closure. Both soil moisture and vapour pressure deficit--the amount of moisture in the air relative to its potential maximum--can govern stomatal closure, which reduces plant carbon uptake. However, plants vary in the degree to which they regulate their stomata--and in association, xylem conductance--in response to increasing aridity: isohydric plants exert tight regulation of stomata and the water content of the plant, whereas anisohydric plants do not. Here we use remote-sensing data sets of anisohydricity and vegetation greenness to show that productivity in United States grasslands--especially anisohydric ones--is far more sensitive to variations in vapour pressure deficit than to variations in precipitation. Anisohydric ecosystem productivity is over three times more sensitive to vapour pressure deficit than isohydric ecosystem productivity. The precipitation sensitivity of summer productivity increases with anisohydricity only for the most anisohydric ecosystems. We conclude that increases in vapour pressure deficit rather than changes in precipitation--both of which are expected impacts of climate change--will be a dominant influence on future grassland productivity.

  17. Modeling Relationships between Shrubland Biomass and Pattern Water Use Efficiency Along Semi-Arid Climatic Gradients

    Science.gov (United States)

    Shoshany, Maxim

    2014-05-01

    A new model is presented that represents the effect of the shrub patches' spatial arrangement on their water use efficiency and biomass productivity in water limited ecosystems. The model utilizes an Edge Ratio parameterization calculated as the ratio between vegetation edge area and the total vegetation area. Pattern Water Use Efficiency employs the following relationships: 1. Water Use efficiency would be directly related to shrub Cover Fraction. 2. Water Use Efficiency would be Inversely related to amount of edge areas (Edge Ratio). 3. The effect of Edge would be Inversely related to shrub cover fraction. 4. The effect of Edge would be Inversely related to the shrubs' height. Pattern Water Use Efficiency than modulates the use of precipitation in producing biomass. Preliminary assessment of the new model was achieved by comparing its results with biomass as extracted from high-resolution imagery based on allometric equations for 18 sites along a climatic gradient between Mediterranean and arid regions in Central Israel. In the next phase, the model is modified to allow its implementation with Landsat Imagery. This form of the model facilitated wide regional mapping of shrublands' biomass. Such mapping is fundamental for assessing the impacts of climate change on ecosystems productivity in desert fringe ecosystems.

  18. Potential of Waste Water Use for Jatropha Cultivation in Arid Environments

    Directory of Open Access Journals (Sweden)

    Folkard Asch

    2012-12-01

    Full Text Available Water is crucial for socio-economic development and healthy ecosystems. With the actual population growth and in view of future water scarcity, development calls for improved sectorial allocation of groundwater and surface water for domestic, agricultural and industrial use. Instead of intensifying the pressure on water resources, leading to conflicts among users and excessive pressure on the environment, sewage effluents, after pre-treatment, provide an alternative nutrient-rich water source for agriculture in the vicinity of cities. Water scarcity often occurs in arid and semiarid regions affected by droughts and large climate variability and where the choice of crop to be grown is limited by the environmental factors. Jatropha has been introduced as a potential renewable energy resource since it is claimed to be drought resistant and can be grown on marginal sites. Sewage effluents provide a source for water and nutrients for cultivating jatropha, a combined plant production/effluent treatment system. Nevertheless, use of sewage effluents for irrigation in arid climates carries the risk of salinization. Thus, potential irrigation with sewage effluents needs to consider both the water requirement of the crop and those needed for controlling salinity build-up in the top soil. Using data from a case study in Southern Morocco, irrigation requirements were calculated using CROPWAT 8.0. We present here crop evapotranspiration during the growing period, required irrigation, the resulting nutrient input and the related risk of salinization from the irrigation of jatropha with sewage effluent.

  19. Seasonal and diurnal variations in methane emissions from Wuliangsu Lake in arid regions of China

    Science.gov (United States)

    Duan, Xiaonan; Wang, Xiaoke; Mu, Yujing; Ouyang, Zhiyun

    CH 4 emissions have been widely studied in various wetlands, such as boreal peatlands, rice paddies, and tropical swamps. However, little investigation has been carried out for CH 4 emissions from lakes or wetlands in arid regions where these freshwaters play a vital role in providing ecosystem services for local people. To quantify the spatial and temporal variations of CH 4 flux and understand its key controlling factors in shallow lakes in arid regions of Western China, CH 4 fluxes from Wuliangsu Lake were measured at different vegetation zones and water depths with a static chamber technique during a growing season from April to October in 2003. Results showed that the average emission flux of CH 4 from submerged plant ( Potamogeton pectinatus) growing zones was 2.16 mg CH 4 m -2 h -1, which was 85.8% lower than that from emergent macrophyte ( Phragmites australis) growing zones. CH 4 emissions increased with increasing water depth in Phragmites Community. Significant seasonal and diurnal variations of CH 4 emission were observed for P. australis during the plant growth stage, for P. pectinatus growing zones, however, the variations were minor. In addition to vegetation cover and water depth, bottom silt temperature and light intensity were also important factors influencing seasonal and diurnal variations of CH 4 flux from Phargmites growing zone.

  20. Climate change mitigation by carbon stock - the case of semi-arid West Africa

    Science.gov (United States)

    Lykke, A. M.; Barfod, A. S.; Tinggaard Svendsen, G.; Greve, M.; Svenning, J.-C.

    2009-11-01

    Semi-arid West Africa has not been integrated into the afforestation/reforestation (AR) carbon market. Most projects implemented under the Clean Development Mechanism (CDM) have focused on carbon emission reductions from industry and energy consumption, whereas only few (only one in West Africa) have been certified for AR carbon sequestration. A proposed mechanism, Reducing Emissions from Deforestation and Degradation (REDD) to be discussed under COP15 aims to reduce emissions by conserving already existing forests. REDD has high potential for carbon stocking at low costs, but focuses primarily on rain forest countries and excludes semi-arid West Africa from the preliminary setup. African savannas have potential to store carbon in the present situation with degrading ecosystems and relatively low revenues from crops and cattle, especially if it is possible to combine carbon stocking with promotion of secondary crops such as food resources and traditional medicines harvested on a sustainable basis. Methods for modelling and mapping of potential carbon biomass are being developed, but are still in a preliminary state. Although economic benefits from the sale of carbon credits are likely to be limited, carbon stocking is an interesting option if additional benefits are considered such as improved food security and protection of biodiversity.

  1. Association of growth related seedling traits in Acacia senegal under arid environment of western Rajasthan.

    Science.gov (United States)

    Pancholy, Anjly; Jindal, S K; Singh, S K; Pathak, Rakesh

    2015-07-01

    Climatic models and predictions indicate increase in aridity world over due to global warming. Arid environments occupy about one third land area of the world. A. senegal is the most important dryland resource of western Rajasthan desert ecosystem. The seeds of 13 low and high seed yielding exotic and indigenous provenances were evaluated for diversity and interrelationship among growth related seedling traits targeting establishment and end use of this species. Under the present study most of the growth related seedling traits varied within and amongst provenances. Highly significant correlation of dry biomass per plant of more than 72% with root length (73.3%), collar diameter (72.2%), shoot dryweight (99.7%), root dry weight (95.7%) and seedling length (79.9%) under the present study may be used for early selection. Similarly, highly significant positive correlation of seedling length with seven out of 12 growth related seedling traits validate strong inherent association of these traits under strong genetic control and are amenable for selection. Significant negative correlation in number of nodules per plant with root/shoot length ratio (-57.6%) and no correlation with 10 out of 12 growth related seedling traits tested advocate emphasis on other growth related seedling traits in selection of elite A. senegal genotypes for afforestation. The non significant associations suggest that per cent germination was independent of other characters and could be selected separately.

  2. Ammonia-oxidising bacteria not archaea dominate nitrification activity in semi-arid agricultural soil.

    Science.gov (United States)

    Banning, Natasha C; Maccarone, Linda D; Fisk, Louise M; Murphy, Daniel V

    2015-06-08

    Ammonia-oxidising archaea (AOA) and bacteria (AOB) are responsible for the rate limiting step in nitrification; a key nitrogen (N) loss pathway in agricultural systems. Dominance of AOA relative to AOB in the amoA gene pool has been reported in many ecosystems, although their relative contributions to nitrification activity are less clear. Here we examined the distribution of AOA and AOB with depth in semi-arid agricultural soils in which soil organic matter content or pH had been altered, and related their distribution to gross nitrification rates. Soil depth had a significant effect on gene abundances, irrespective of management history. Contrary to reports of AOA dominance in soils elsewhere, AOA gene copy numbers were four-fold lower than AOB in the surface (0-10 cm). AOA gene abundance increased with depth while AOB decreased, and sub-soil abundances were approximately equal (10-90 cm). The depth profile of total archaea did not mirror that of AOA, indicating the likely presence of archaea without nitrification capacity in the surface. Gross nitrification rates declined significantly with depth and were positively correlated to AOB but negatively correlated to AOA gene abundances. We conclude that AOB are most likely responsible for regulating nitrification in these semi-arid soils.

  3. AN ECOSYSTEM SERVICE-BASED APPROACH TO DESIGN AGRI- ENVIRONMENT-CLIMATE PAYMENTS FOR THE RURAL DEVELOPMENT PROGRAMS 2014-2020. THE CASE OF THE AUTONOMOUS PROVINCE OF TRENTO

    Directory of Open Access Journals (Sweden)

    A. La Notte

    2014-04-01

    Full Text Available The justification for measures addressing Agri- Environment-Climate payments (AEC is a crucial issue for authorities working at the Rural Development Program (RDP. The RDP 2014-2020 offers the possibility to include environmental benefits and externalities as elements that drive decision-making. Such benefits and externalities include the ecosystem services (ES provided by farming practices in semi-natural ecosystems such as alpine pastures and mountain hay meadows. An approach based on ES is proposed to support and to account for AEC measures in the Autonomous Province of Trento, relying on decision models and scenario analysis. The method is still in development and is currently being tested as to its effectiveness. In the present paper, however, we present the approach and the case study area, with preliminary insights and expected results. The decision framework consists of livestock management and alpine grassland use; its objective is the sustainable production of fodder, compatible with conservation of grassland biodiversity. In addition to habitat for biodiversity, other ES such as water purification, aesthetic and recreation value will be considered in subsequent steps. The need for simplification and reliability, along with data scarcity, strongly limits the degree of sophistication and makes it challanging to create a tool, which is accurate and easy-to-use at the same time.

  4. Groundtruthing Notes and Miscellaneous Biological Datasets from Coral Ecosystems Surveys from the Northwestern Hawaiian Islands Rapid Reef Assessment and Monitoring Program of 2000-2002 (NODC Accession 0001448)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Northwestern Hawaiian Islands Coral Reef Assessment and Monitoring Program (NOWRAMP) began in 2000 with the mission to rapidly evaluate and map the shallow water...

  5. Salinity shapes food webs in shallow lakes: implications for increasing aridity with climate change

    DEFF Research Database (Denmark)

    Vidal, Nicolas; Yu, Jinlei; Gutierrez, Maria Florencia

    2015-01-01

    A reduction in runoff and higher evaporation rates are expected to occur towards 2050 in arid and semiarid regions of the world, resulting in a reduction of water level and salinization of inland waters. Besides the natural process of catchment erosion, human activities such as irrigation of crops...... may also increase salinization. Reduced biodiversity in freshwater systems is the most commonly reported effect of salinization, which may have implications for food web structure and likely for ecosystem functioning as well. The objective of the study was to analyze the effects of salinity...... on community and food web structure in 24 lakes along a wide salinity gradient, from freshwater (0.5 g L-1) to hypersaline lakes (115 g L-1), in a semiarid region in North West China. Fish, zooplankton and macroinvertebrate communities were sampled during July 2014 for determination of taxonomy and size...

  6. Ecosystems of the Great Land. Teacher's Guide.

    Science.gov (United States)

    Strom-Aronson, Melissa; Pohl, Janis

    This is the Teacher's Guide for six video programs: "Introduction to Ecosystems"; "Tundra"; "Coastal Forest"; "Oceans"; "Impact of Human Habitation"; and "Taiga". The programs are designed to fit into courses for students from grades five through high school in which ecology is taught.…

  7. Fishing for ecosystem services

    Science.gov (United States)

    Pope, Kevin L.; Pegg, Mark A.; Cole, Nicholas W.; Siddons, Stephen F.; Fedele, Alexis D.; Harmon, Brian S.; Ruskamp, Ryan L.; Turner, Dylan R.; Uerling, Caleb C.

    2016-01-01

    Ecosystems are commonly exploited and manipulated to maximize certain human benefits. Such changes can degrade systems, leading to cascading negative effects that may be initially undetected, yet ultimately result in a reduction, or complete loss, of certain valuable ecosystem services. Ecosystem-based management is intended to maintain ecosystem quality and minimize the risk of irreversible change to natural assemblages of species and to ecosystem processes while obtaining and maintaining long-term socioeconomic benefits. We discuss policy decisions in fishery management related to commonly manipulated environments with a focus on influences to ecosystem services. By focusing on broader scales, managing for ecosystem services, and taking a more proactive approach, we expect sustainable, quality fisheries that are resilient to future disturbances. To that end, we contend that: (1) management always involves tradeoffs; (2) explicit management of fisheries for ecosystem services could facilitate a transition from reactive to proactive management; and (3) adaptive co-management is a process that could enhance management for ecosystem services. We propose adaptive co-management with an ecosystem service framework where actions are implemented within ecosystem boundaries, rather than political boundaries, through strong interjurisdictional relationships.

  8. Fishing for ecosystem services.

    Science.gov (United States)

    Pope, Kevin L; Pegg, Mark A; Cole, Nicholas W; Siddons, Stephen F; Fedele, Alexis D; Harmon, Brian S; Ruskamp, Ryan L; Turner, Dylan R; Uerling, Caleb C

    2016-12-01

    Ecosystems are commonly exploited and manipulated to maximize certain human benefits. Such changes can degrade systems, leading to cascading negative effects that may be initially undetected, yet ultimately result in a reduction, or complete loss, of certain valuable ecosystem services. Ecosystem-based management is intended to maintain ecosystem quality and minimize the risk of irreversible change to natural assemblages of species and to ecosystem processes while obtaining and maintaining long-term socioeconomic benefits. We discuss policy decisions in fishery management related to commonly manipulated environments with a focus on influences to ecosystem services. By focusing on broader scales, managing for ecosystem services, and taking a more proactive approach, we expect sustainable, quality fisheries that are resilient to future disturbances. To that end, we contend that: (1) management always involves tradeoffs; (2) explicit management of fisheries for ecosystem services could facilitate a transition from reactive to proactive management; and (3) adaptive co-management is a process that could enhance management for ecosystem services. We propose adaptive co-management with an ecosystem service framework where actions are implemented within ecosystem boundaries, rather than political boundaries, through strong interjurisdictional relationships. Published by Elsevier Ltd.

  9. Columbia River Estuary Ecosystem Classification Ecosystem Complex

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Estuarine ecosystems are controlled by a variety of processes that operate at multiple spatial and temporal scales. Understanding the hierarchical nature of these...

  10. Permafrost distribution modelling in the semi-arid Chilean Andes

    National Research Council Canada - National Science Library

    Azócar, Guillermo F; Brenning, Alexander; Bodin, Xavier

    2017-01-01

    ...; this kind of model approach has never been applied for a large portion of the Andes. In the present study, this methodology is applied to map permafrost favourability throughout the semi-arid Andes of central Chile (29–32...

  11. Impact of sustained drought on a semi-arid Colophospermum ...

    African Journals Online (AJOL)

    Keywords: botany; Colophospermum mopane; composition change; drought; impact; mopane; Mopani Veld; mortality; Northern Province; perennial grass; recruitment; savanna; semi-arid; South Africa; vegetation changes; abundance; browsing; browsing pressure; combretum apiculatum; condition; decline; dominance; ...

  12. Aquaculture in desert and arid lands: development constraints and opportunities

    National Research Council Canada - National Science Library

    Crespi, V; Lovatelli, A

    2011-01-01

    Aquaculture in desert and arid lands has been growing steadily over the last decade thanks to the modern technologies and alternative energy sources that have allowed water in these places of extremes...

  13. Application of Terrestrial Ecosystem Monitoring under the CAFF Circumpolar Biodiversity Monitoring Program: Designing and Implementing Terrestrial Monitoring to Establish the Canadian High Arctic Research Station as a Flagship Arctic Environmental Monitoring Site

    Science.gov (United States)

    McLennan, D.; Kehler, D.

    2016-12-01

    The Canadian High Arctic Research Station (CHARS) is scheduled for completion in July 2017 and is the northern science component of Polar Knowledge Canada (POLAR). A mandated goal for POLAR is to establish the adjacent Experimental and Reference Area (ERA) as an Arctic Flagship monitoring site that will track change in Arctic terrestrial, freshwater and marine ecosystems. Situated in the community of Cambridge Bay, CHARS provides the opportunity to draw on the Indigenous Knowledge of local residents to help design and conduct the monitoring, and to operate 12 months a year. Monitoring at CHARS will be linked to networks nationally and internationally, and is being designed so that change in key indicators can be understood in terms of drivers and processes, modeled and scaled up regionally, and used to predict important changes in critical indicators. As a partner in the Circumpolar Biodiversity Monitoring Program (CBMP), the monitoring design for terrestrial ecosystems follows approaches outlined by the CBMP Terrestrial Expert Monitoring Group, who have listed key monitoring questions and identified a list of important Focal Ecosystem Components (FECs). To link drivers to FECs we are proposing a multi-scaled approach: 1) an Intensive Monitoring Area to establish replicated monitoring plots that track change in snow depth and condition, active layer depth, soil temperature, soil moisture, and soil solution chemistry that are spatially and temporally linked to changes in microbiological activity, CO2/CH4 net ecosystem flux, vegetation relative frequency, species composition, growth and foliar nutrient concentration, arthropod abundance, lemming abundance and health, and shorebird/songbird abundance and productivity. 2) These intensive observations are supported by watershed scale measures that will monitor, during the growing season, lemming winter nest abundance, songbird, shorebird and waterfowl staging and nesting, and other observations; in the winter we will

  14. Application of a statistical model for the assessment of environmental quality in neotropical semi-arid reservoirs.

    Science.gov (United States)

    de Lira Azevêdo, Evaldo; de Lucena Barbosa, José Etham; Viana, Leandro Gomes; Anacleto, Maria José Pinheiro; Callisto, Marcos; Molozzi, Joseline

    2017-02-01

    The aim of this study was to develop a statistical model to assess the environmental quality of reservoirs located in semi-arid region using metrics of anthropogenic disturbance, water quality variables, and benthic macroinvertebrate communities as indicators. The proposed model was applied to 60 sites located in three reservoirs in the Paraíba river basin, Brazilian semi-arid region. Collections were made in December 2011. In each site, we collected one sample of benthic macroinvertebrates and one water sample for the determination of physical and chemical parameters. Characterization of the landscape was made through application of 10 physical habitat protocols on each site for the collected information on disturbance and subsequent calculation of disturbance metrics. The results showed the formation of two groups: group 1, consisting of 16 minimally altered sites, and group 2, with 44 severely altered sites. The proposed statistical model was sensitive enough to detect changes. In the minimally altered group, the Chironomids Aedokritus and Fissimentum were dominant, indicating a higher environmental quality, while Coelotanypus and Chironomus were abundant in severely altered sites with lower environmental quality. The conservation and management of reservoirs in semi-arid regions should be intensified in view of the need to maintain the environmental quality of these ecosystems.

  15. Risk and markets for ecosystem services.

    Science.gov (United States)

    Bendor, Todd K; Riggsbee, J Adam; Doyle, Martin

    2011-12-15

    Market-based environmental regulations (e.g., cap and trade, "payments for ecosystem services") are increasingly common. However, few detailed studies of operating ecosystem markets have lent understanding to how such policies affect incentive structures for improving environmental quality. The largest U.S. market stems from the Clean Water Act provisions requiring ecosystem restoration to offset aquatic ecosystems damaged during development. We describe and test how variations in the rules governing this ecosystem market shift risk between regulators and entrepreneurs to promote ecological restoration. We analyze extensive national scale data to assess how two critical aspects of market structure - (a) the geographic scale of markets and (b) policies dictating the release of credits - affect the willingness of entrepreneurs to enter specific markets and produce credits. We find no discernible relationship between policies attempting to ease market entry and either the number of individual producers or total credits produced. Rather, market entry is primarily related to regional geography (the prevalence of aquatic ecosystems) and regional economic growth. Any improvements to policies governing ecosystem markets require explicit evaluation of the interplay between policy and risk elements affecting both regulators and entrepreneurial credit providers. Our findings extend to emerging, regulated ecosystem markets, including proposed carbon offset mechanisms, biodiversity banking, and water quality trading programs.

  16. Enhanced cold-season warming in semi-arid regions

    Directory of Open Access Journals (Sweden)

    J. Huang

    2012-06-01

    Full Text Available This study examined surface air temperature trends over global land from 1901–2009. It is found that the warming trend was particularly enhanced, in the boreal cold season (November to March over semi-arid regions (with precipitation of 200–600 mm yr−1 showing a temperature increase of 1.53 °C as compared to the global annual mean temperature increase of 1.13 °C over land. In mid-latitude semi-arid areas of Europe, Asia, and North America, temperatures in the cold season increased by 1.41, 2.42, and 1.5 °C, respectively. The semi-arid regions contribute 44.46% to global annual-mean land-surface temperature trend. The mid-latitude semi-arid regions in the Northern Hemisphere contribute by 27.0% of the total, with the mid-latitude semi-arid areas in Europe, Asia, and North America accounting for 6.29%, 13.81%, and 6.85%, respectively. Such enhanced semi-arid warming (ESAW imply drier and warmer trend of these regions.

  17. Surficial weathering of iron sulfide mine tailings under semi-arid climate.

    Science.gov (United States)

    Hayes, Sarah M; Root, Robert A; Perdrial, Nicolas; Maier, Raina; Chorover, Jon

    2014-09-15

    Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering under semi-arid climate at an EPA Superfund Site in semi-arid central Arizona (USA). Here we report a multi-method data set combining wet chemical and synchrotron-based X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES) methods to resolve the tight coupling of iron (Fe) and sulfur (S) geochemical changes in the top 2 m of tailings. Despite nearly invariant Fe and S concentration with depth (130-140 and 100-120 g kg-1, respectively), a sharp redox gradient and distinct morphological change was observed within the top 0.5 m, associated with a progressive oxidative alteration of ferrous sulfides to (oxyhydr)oxides and (hydroxy)sulfates. Transformation is nearly complete in surficial samples. Trends in molecular-scale alteration were co-located with a decrease in pH from 7.3 to 2.3, and shifts in Fe and S lability as measured via chemical extraction. Initial weathering products, ferrihydrite and gypsum, transform to schwertmannite, then jarosite-group minerals with an accompanying decrease in pH. Interestingly, thermodynamically stable phases such as goethite and hematite were not detected in any samples, but ferrihydrite was observed even in the

  18. Springs as Ecosystems: Clarifying Groundwater Dependence and Wetland Status (Invited)

    Science.gov (United States)

    Stevens, L.; Springer, A. E.; Ledbetter, J. D.

    2013-12-01

    Springs ecosystems are among the most productive, biologically diverse and culturally important ecosystems on Earth. Net annual productivity of some springs exceeds 5 kg/m^2/yr. Springs support an estimated 19% of the endangered species and numerous rare taxa in the United States. Springs serve as keystone ecosystems in arid regions, and as cornerstones of indigenous cultural well-being, history, economics, and aesthetics. Despite their significance, the ecosystem ecology and stewardship of springs have received scant scientific and public attention, resulting in loss or impairment of 50-90% of the springs in many regions, both arid and temperate. Six reasons contribute to the lack of attention to springs. Springs are poorly mapped because: 1) their generally small size is less than the pixel area of most remote sensing analyses and they are overlooked; and 2) springs detection is often limited by emergence on cliff faces, beneath heavy vegetation cover, or under water. In addition, 3) high levels of ecosystem complexity at springs require multidisciplinary team approaches for inventory, assessment, and research, but collaboration between the fields of hydrogeology and ecology has been limited. 4) Protectionism by land owners and organizations that manage springs limits the availability information, preventing regional assessment of status. 5) Prior to recent efforts, the absence of a descriptive lexicon of springs types has limited discussion about variation in ecological characteristics and processes. 6) Neither regarded entirely as groundwater or as surface water, springs fall 'between jurisdictional cracks' and are not subject to clear legal and regulatory oversight. With regards to the latter point, two jurisdictional phrases have reduced scientific understanding and stewardship of springs ecosystems: 'jurisdictional wetlands' and 'groundwater-dependent ecosystems' (GDEs). Most springs have insufficient monitoring data to establish perenniality or the range of

  19. Demographic noise and resilience in a semi-arid ecosystem model

    NARCIS (Netherlands)

    Realpe-Gomez, J.; Baudena, M.; Galla, T.; McKane, A.J.; Rietkerk, M.

    2013-01-01

    The scarcity of water characterising drylands forces vegetation to adopt appropriate survival strategies. Some of these generate water–vegetation feedback mechanisms that can lead to spatial self-organisation of vegetation, as it has been shown with models representing plants by a density of

  20. Hydraulic redistribution by two semi-arid shrub species: implications for Sahelian agro-ecosystems

    Science.gov (United States)

    F. Kizito; M.I. Dragila; M. Sene; J.R. Brooks; F.C. Meinzer; I. Diedhiou; M. Diouf; A. Lufafa; R.P. Dick; J. Selker; R. Cuenca

    2012-01-01

    Hydraulic redistribution is the process of passive water movement from deeper moist soil to shallower dry soil layers using plant roots as conduits. Results from this study indicate that this phenomenon exists among two shrub species (Guiera senegalensis and Piliostigma reticulatum) that co-exist with annual food crops in...

  1. Multi-functional landscapes in semi arid environments: implications for biodiversity and ecosystem services

    CSIR Research Space (South Africa)

    O'Farrell, PJ

    2010-06-01

    Full Text Available :306–316 813Belnap J, Phillips SL, Flint S, Money J, Caldwell M (2008) 814Global change and biological soil crusts: effects of ultra- 815violet augmentation under altered precipitation regimes 816and nitrogen additions. Glob Change Biol 14:670–686 817...

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

    NARCIS (Netherlands)

    Poulter, B.; Frank, D.; Ciais, P.; Myneni, R.B.; Andela, N.; Bi, J.; Broquet, G.; Canadell, J.G.; Chevallier, F.; Liu, Y.Y.; Running, S.W.; Sitch, S.; van der Werf, G.R.

    2014-01-01

    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

  3. Spatial variability in the speciation and bioaccumulation of mercury in an arid subtropical reservoir ecosystem.

    Science.gov (United States)

    Becker, Jesse C; Groeger, Alan W; Nowlin, Weston H; Chumchal, Matthew M; Hahn, Dittmar

    2011-10-01

    Patterns of spatial variation of mercury and methylmercury (MeHg) were examined in sediments and muscle tissue of largemouth bass (Micropterus salmoides) from Amistad International Reservoir, a large and hydrologically complex subtropical water body in the Rio Grande drainage. The distributions of both Hg and MeHg were compared with environmental and biological factors known to influence production of MeHg. The highest concentrations of total Hg (THg) in sediment were found in the Rio Grande arm of the reservoir, whereas MeHg was highest at sites in the Devils River arm and inundated Pecos River (often more than 3.0 ng/g). Conditions in the sediments of the Devils River arm and Pecos River channel were likely more favorable to the production of MeHg, with higher sediment porewater dissolved organic carbon, and porewater sulfate levels in the optimal range for methylation. Although the detection of different groups of sulfate-reducing bacteria by polymerase chain reaction (PCR) was generally correlated with MeHg concentrations, bacterial counts via fluorescent in situ hybridization (FISH) did not correlate with MeHg. A sample of 156 largemouth bass (35 cm), 77% exceeded the 0.3 mg/kg U.S. Environmental Protection Agency screening value. This study shows that significant variation in sediment MeHg and biotic Hg concentration can exist within lakes and reservoirs and that it can correspond to variation in environmental conditions and Hg methylation. Copyright © 2011 SETAC.

  4. A spatial assessment of riverine ecosystems and water supply in a semi-arid environment

    CSIR Research Space (South Africa)

    Smith-Adao, LB

    2011-12-01

    Full Text Available and the impacts of other anthropogenic activities including abstraction of freshwater which otherwise would have diluted the return flows. Only the middle reaches of the Gouritz and Groot Rivers represent a possible win–win situation for both the environment...

  5. Directional climate change and potential reversal of desertification in arid and semiarid ecosystems

    Science.gov (United States)

    Our objective was to determine if long-term increases in precipitation can maintain grasslands susceptible to desertification, and initiate a reversal of historic regime shifts on desertified shrublands. Long-term trends in desertification were documented using vegetation maps beginning in 1858. The...

  6. Soil microbial community response to precipitation change in a semi-arid ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Cregger, Melissa [ORNL; Schadt, Christopher Warren [ORNL; McDowell, Nathan [Los Alamos National Laboratory (LANL); Pockman, William [University of New Mexico, Albuquerque; Classen, Aimee T [University of Tennessee, Knoxville (UTK)

    2012-01-01

    Microbial communities regulate many belowground carbon cycling processes; thus, the impact of climate change on the struc- ture and function of soil microbial communities could, in turn, impact the release or storage of carbon in soils. Here we used a large-scale precipitation manipulation ( 18%, 50%, or ambient) in a pi on-juniper woodland (Pinus edulis-Juniperus mono- sperma) to investigate how changes in precipitation amounts altered soil microbial communities as well as what role seasonal variation in rainfall and plant composition played in the microbial community response. Seasonal variability in precipitation had a larger role in determining the composition of soil microbial communities in 2008 than the direct effect of the experimental precipitation treatments. Bacterial and fungal communities in the dry, relatively moisture-limited premonsoon season were compositionally distinct from communities in the monsoon season, when soil moisture levels and periodicity varied more widely across treatments. Fungal abundance in the drought plots during the dry premonsoon season was particularly low and was 4.7 times greater upon soil wet-up in the monsoon season, suggesting that soil fungi were water limited in the driest plots, which may result in a decrease in fungal degradation of carbon substrates. Additionally, we found that both bacterial and fungal communities beneath pi on pine and juniper were distinct, suggesting that microbial functions beneath these trees are different. We conclude that predicting the response of microbial communities to climate change is highly dependent on seasonal dynam- ics, background climatic variability, and the composition of the associated aboveground community.

  7. Arid Lands Ecology Facility management plan

    Energy Technology Data Exchange (ETDEWEB)

    None

    1993-02-01

    The Arid Lands Ecology (ALE) facility is a 312-sq-km tract of land that lies on the western side of the Hanford Site in southcentral Washington. The US Atomic Energy Commission officially set aside this land area in 1967 to preserve shrub-steppe habitat and vegetation. The ALE facility is managed by Pacific Northwest Laboratory (PNL) for the US Department of Energy (DOE) for ecological research and education purposes. In 1971, the ALE facility was designated the Rattlesnake Hills Research Natural Area (RNA) as a result of an interagency federal cooperative agreement, and remains the largest RNA in Washington. it is also one of the few remaining large tracts of shrub-steppe vegetation in the state retaining a predominant preeuropean settlement character. This management plan provides policy and implementation methods for management of the ALE facilities consistent with both US Department of Energy Headquarters and the Richland Field Office decision (US Congress 1977) to designate and manage ALE lands as an RNA and as a component of the DOE National Environmental Research Park System.

  8. Cisterns as sediment archives in arid environments

    Science.gov (United States)

    Junge, Andrea; Shahack-Gross, Ruth; Lomax, Johanna; Finkelstein, Israel; Fuchs, Markus

    2017-04-01

    Ancient cisterns are frequently occurring archaeological structures in semiarid, arid and hyperarid regions. These systems to collect and store water were constructed to enable the establishment of settlements, livestock farming and agricultural activity even under dry conditions. During precipitation events surface runoff from adjoining slopes erodes and transports sediments, which then can be deposited in the cistern. Therefore, these archaeological structures serve also as sediment traps and represent the fluvial processes of the cistern's catchment. Additionally, the cisterns are usually constructed to prevent any water outlet, resulting in an undisturbed, often continuous sediment record. Crucial for investigating cisterns and their sediments is the establishment of robust chronologies, with optical stimulated luminescence (OSL) dating as the preferred dating method. This enables to determine the time of construction, utilisation and abandonment of the cistern. In addition, the sediment record within the cistern represents an archive including numerous environmental proxies (e. g. pollen), which can be used for palaeoenvironmental reconstruction, serving as an important paleoenvironmental archive in dryland areas, where continuous sediment records are rare.

  9. Radar Remote Sensing of Arid Regions

    Science.gov (United States)

    Elsherbini, Adel A.

    An Interferometric Synthetic Aperture Radar (InSAR) system to map the bedrock topography underneath the sand in deserts and arid areas is presented. It is anticipated to greatly increase the efficiency of oil field and ground water exploration as well as environmental and archaeological studies. The proposed system consists of two InSAR subsystems, one operating at Ka-band to map the sand topography and the other operates in the VHF band to map the subsurface topography. It is shown that conventional InSAR processing produces unacceptable error in height estimation since it does not account for the refraction and the different propagation velocity in the sand. Thus, a new inversion algorithm is developed which can be used to accurately estimate the bedrock topography for arbitrary sand and bedrock geometries. The inversion algorithm is verified experimentally using a scaled model in the lab. One of the main concerns was the use of conventional SAR focusing techniques for imaging the subsurface region. This can result in significant image degradation and lower limit on the minimum achievable azimuth resolution. Thus, a new subsurface iterative focusing technique is developed to address these challenges. One of the main practical system implementation issues is the antenna design for the VHF system since very wideband and very compact antennas are desired. Thus a number of compact and low profile Ultra-Wideband antennas are also developed. These antennas have sub-wavelength sizes and most of them have bandwidths exceeding one octave. (Abstract shortened by UMI.)

  10. 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.

  11. Quality of urban runoff in wet and dry seasons: a case study in a semi-arid zone.

    Science.gov (United States)

    Ortiz-Hernández, Joyce; Lucho-Constantino, Carlos; Lizárraga-Mendiola, Liliana; Beltrán-Hernández, Rosa Icela; Coronel-Olivares, Claudia; Vázquez-Rodríguez, Gabriela

    2016-12-01

    Urban runoff (UR) is a promising new resource that may alleviate growing tensions in numerous arid and semi-arid regions of the world. However, it is precisely in these zones that the available UR quality characteristics are scarcer. This work aims to evaluate a wide set of parameters to establish a detailed approach to both the quality of UR in a midsized city in Central Mexico and the feasibility of using UR to recharge aquifers. UR from an institutional land use site was sampled during wet and dry seasons and assessed for suspended solids, organic matter, nutrients, microorganisms, metals, and persistent organic chemicals (i.e., polycyclic aromatic hydrocarbons, PAH). The results were analyzed using multivariate statistical methods to identify relationships among the variables, the sampling sites and the seasons. The soil erosion and the leaching of materials due to the water flow through vegetated areas were identified as the most influencing factor on the quality of the site runoff in both dry and wet seasons. Additionally, data were more heterogeneous during the dry season, and higher pollutant concentrations were found both during the dry season and in more pervious zones. We consider UR a promising water source for recharging aquifers in arid and semi-arid zones if a program is implemented that can integrate an adequate runoff treatment system, soil protection, and other non-structural measures.

  12. Influence of Vegetation Cover on Rain Pulse Responses in Semi-Arid Savannas in Central Texas

    Science.gov (United States)

    Litvak, M.; Heilman, J.; McInnes, K.; Thijs, A.; Kjelgaard, J.

    2007-12-01

    Savannas in central Texas are dominated by live oak (Quercus virginiana) and Ashe juniper (Juniperus asheii) underlain by perennial, C3/C4 grasslands, and are increasingly becoming juniper and mesquite dominated due to overgrazing and suppression of wildfires. Since 2004, we have been investigating how carbon, water and energy exchange in these rain-limited savannas respond to rainfall variability and this observed vegetation change. In semi-arid regions, rainfall pulses provide inputs of soil moisture and trigger biotic activity in the form of plant gas exchange and microbial metabolism as well as water dependent physical processes in the soil. Each of these components has a different characteristic response curve to soil moisture and integrates soil water content over a different range of depths. Here we focus on examining how the observed increase of woody species in central Texas savannas alters the response of net ecosystem exchange and its components, ecosystem respiration and gross ecosystem exchange, to rain pulses. Using data we have collected over the last three years from three Ameriflux tower sites at Freeman Ranch near San Marcos, TX (C3/C4 grassland, juniper/mesquite savanna with 50 percent woody cover, and oak/juniper woodland), we quantify the responses of both ecosystem respiration and daily carbon uptake to rainfall pulses throughout the year. Specifically, we look at the enhancement and persistence of ecosystem respiration and carbon uptake responses following a pulse, and isolate the main controlling factors on the observed response: seasonality, antecedent soil moisture and temperature, or previous pulses. In all three land covers, the general response to precipitation pulses is a respiration pulse followed by an increase in total carbon uptake. Differences in pulse responses observed at the savanna site compared to the grassland and woodland sites can be explained, in part, by the observed differences in rooting structure and photosynthetic

  13. Seal formation in arid soil under natural and laboratory conditions

    Science.gov (United States)

    Sarah, Pariente; Sachs, Eyal

    2013-04-01

    Runoff is of considerable importance in the functioning of a desert ecosystem. The hydrological characteristics of runoff developing on arid soil under natural field conditions and those of runoff occurring in laboratory-controlled rain simulation experiments using the same type of soil were investigated. Runoff and erosion measurements were carried out in small plots (0.2-0.8 m2) on a south-facing hillslope in the northern Negev, Israel (90 mm ave. annual rainfall). Soil from the area near to the runoff plots was collected for the rain simulation experiments conducted in the laboratory. The soil was collected from 0-1 cm and 1-5 cm depths, and then placed within boxes (1.16 m long and 0.55 m wide) in the laboratory in the same order as they had been in the field. Representative surface stones were collected in the field and scattered randomly on the soil surface in the laboratory boxes. In some of the laboratory experiments soil, 5 cm in depth, was placed on a geotechnical sheet on a metal screen, while in other experiments, soil of 5 cm depth was placed on a Terzaghi filter. Rain simulator used had a rotating disk with a tilted nozzle to simulate raindrop size dispersion and kinetic energy of natural rain. The sprinkling intensity was set at a rate of 18 mm/hour. Soil crusts in the field were more stable than those created in the lab for two standard tests: Emerson - immersion test, and the 'single water drop' test. Whereas weak activity of microphytes was found in the field there was no such activity in the lab. The rain depth until runoff in the field was less than under laboratory conditions, while the sediment yield was greater in the field than in the laboratory (8.64 g/m2 versus 0.58 g/m2). The rain simulator experiments that had included a Terzaghi filter showed significantly higher final infiltration rate (7.5 mm/h versus 4.2 mm/h), shorter accumulated watering depth until stabilization of soil seal formation (100-200 mm versus 50 mm), and smaller

  14. Environmental Controls on Carbon Dioxide Flux in a Semi-arid Grassland of Mongolia

    Science.gov (United States)

    Nakano, T.; Nemoto, M.; Shinoda, M.

    2006-12-01

    The Mongolian steppe zone is one of the main components of central-Asian grasslands. CO2 exchange rates between the atmosphere and the steppe ecosystem were measured in a Mongolian semi-arid grassland in July 2004, May 2005, July 2005, September 2005, and June 2006 by using a closed-chamber technique. The study area is dominated by Poaceous grasses and was enclosed by a fence (300 m x 300 m) in June 2004 to prevent livestock from grazing. We used transparent and opaque chambers to separately evaluate net ecosystem CO2 exchange (NEE), ecosystem respiration (Reco), and gross primary production (GPP). Along with CO2 flux measurements, air and soil temperatures, relative humidity, precipitation, photosynthetically active radiation (PAR), and soil volumetric water content were continuously measured. Aboveground plant biomass was also determined by clipping vegetation for each observation period. From the measured data of CO2 fluxes and environmental variables, their quantitative relationships were examined. GPP was highly correlated with the aboveground biomass, hence we normalized GPP values by the amount of aboveground biomass. Photosynthetic light-response curves for the normalized GPP did not differ among the observation periods (i.e., growth stages of the grasses). However, the curves differed significantly among different soil moisture conditions, suggesting that the light-response of grasses declined as soil dried. In addition, reduced GPP was observed under extremely hot and dry atmospheric conditions. We found significant relationships between Reco and both of the soil temperature and moisture. Our results also indicated that the Q10 values (temperature sensitivity of ecosystem respiration) increased with the increased soil moisture.

  15. Ecosystems and Land Use Change

    Science.gov (United States)

    DeFries, Ruth S.; Asner, Gregory P.; Houghton, Richard A.

    Land use is at the center of one of the most vexing challenges for the coming decades: to provide enough food, fiber and shelter for the world's population; raise the standard of living for the billion people currently below the poverty line; and simultaneously sustain the world's ecosystems for use by humans and other species. The intended consequence of cropland expansion, urban growth, and other land use changes is to satisfy demands from the increasing appetite of the world's population. Unintended consequences, however, can alter ecological processes and have far-reaching and long-term effects that potentially compromise the basic functioning of ecosystems. Recently, the scientific community has begun to confront such issues. Several national and international programs have been at the forefront of scientific enquiry on the causes and consequences of land use change, including: the Land Use and Land Cover Change Program of the National Aeronautics and Space Administration, the Land Use program element in the interagency U.S. Climate Change Science Program, and the International Geosphere-Biosphere's Land Use and Cover Change (LUCC) core project. The result has been significant advances in understanding the complex socioeconomic, technological, and biophysical factors that drive land use change worldwide.

  16. 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

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

    Science.gov (United States)

    Xing, Wen; Wang, Bin

    2017-07-01

    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.

  18. Predictability and Prediction of Summer Rainfall in the Arid/Semi-arid Regions of China

    Science.gov (United States)

    Wang, B.; Xing, W.

    2016-12-01

    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 is 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.

  19. Identification and functional characterization of a novel bipartite nuclear localization sequence in ARID1A

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, Nicholas W. [Women' s Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale 22003, VA (United States); The John P. Murtha Cancer Center, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda 20889, MD (United States); Shoji, Yutaka [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids 49503, MI (United States); Conrads, Kelly A.; Stroop, Kevin D. [Women' s Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale 22003, VA (United States); Hamilton, Chad A. [Women' s Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale 22003, VA (United States); The John P. Murtha Cancer Center, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda 20889, MD (United States); Gynecologic Oncology Service, Department of Obstetrics and Gynecology, Walter Reed National Military Medical Center, 8901 Wisconsin Ave, MD, Bethesda, 20889 (United States); Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda 20814, MD (United States); Darcy, Kathleen M. [Women' s Health Integrated Research Center at Inova Health System, Gynecologic Cancer Center of Excellence, Annandale 22003, VA (United States); The John P. Murtha Cancer Center, Walter Reed National Military Medical Center, 8901 Wisconsin Avenue, Bethesda 20889, MD (United States); Maxwell, George L. [Department of Obstetrics and Gynecology, Inova Fairfax Hospital, Falls Church, VA 22042 (United States); Risinger, John I. [Department of Obstetrics, Gynecology and Reproductive Biology, Michigan State University, Grand Rapids 49503, MI (United States); and others

    2016-01-01

    AT-rich interactive domain-containing protein 1A (ARID1A) is a recently identified nuclear tumor suppressor frequently altered in solid tumor malignancies. We have identified a bipartite-like nuclear localization sequence (NLS) that contributes to nuclear import of ARID1A not previously described. We functionally confirm activity using GFP constructs fused with wild-type or mutant NLS sequences. We further show that cyto-nuclear localized, bipartite NLS mutant ARID1A exhibits greater stability than nuclear-localized, wild-type ARID1A. Identification of this undescribed functional NLS within ARID1A contributes vital insights to rationalize the impact of ARID1A missense mutations observed in patient tumors. - Highlights: • We have identified a bipartite nuclear localization sequence (NLS) in ARID1A. • Confirmation of the NLS was performed using GFP constructs. • NLS mutant ARID1A exhibits greater stability than wild-type ARID1A.

  20. Dynamic belowground ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Harris, W. F.; Santantonio, D.; McGinty, D.

    1979-01-01

    Roots comprise the primary interface between plant and soil for uptake of water and nutrients. Much is known about the biochemistry, cell physiology and membrane physics associated with these important processes. In this paper we discuss the role of the belowground ecosystem, especially the autotrophic root component, in the structure and function of forest ecosystems. Beyond recognizing roles of anchoring terrestrial plants and uptake of water and nutrients, this component of the forest has been largely neglected in an ecosystem context. In order to focus discussion on the properties of the belowground ecosystem, we use the term rhizosphere to include roots, mycorrhizae, microbes, and rhizophagus invertebrates.

  1. Seedbed preparation influence on morphometric characteristics of perennial grasses of a semi-arid rangeland in Kenya

    OpenAIRE

    Opiyo, Francis EO; Ekaya, Wellington N; Nyariki, Dickson M; Mureithi, Stephen Mwangi

    2011-01-01

    Semi-arid rangelands in Kenya are an important source of forage for both domestic and wild animals. However, indigenous perennial grasses notably Cenchrus ciliaris (African foxtail grass), Eragrostis superba (Maasai love grass) and Enteropogon macrostachyus (Bush rye grass) are disappearing at an alarming rate. Efforts to re-introduce them through restoration programs have often yielded little success. This can partly be attributed to failure of topsoil to capture and store scarce water to me...

  2. Going beyond the Millennium Ecosystem Assessment: an index system of human dependence on ecosystem services.

    Science.gov (United States)

    Yang, Wu; Dietz, Thomas; Liu, Wei; Luo, Junyan; Liu, Jianguo

    2013-01-01

    The Millennium Ecosystem Assessment (MA) estimated that two thirds of ecosystem services on the earth have degraded or are in decline due to the unprecedented scale of human activities during recent decades. These changes will have tremendous consequences for human well-being, and offer both risks and opportunities for a wide range of stakeholders. Yet these risks and opportunities have not been well managed due in part to the lack of quantitative understanding of human dependence on ecosystem services. Here, we propose an index of dependence on ecosystem services (IDES) system to quantify human dependence on ecosystem services. We demonstrate the construction of the IDES system using household survey data. We show that the overall index and sub-indices can reflect the general pattern of households' dependences on ecosystem services, and their variations across time, space, and different forms of capital (i.e., natural, human, financial, manufactured, and social capitals). We support the proposition that the poor are more dependent on ecosystem services and further generalize this proposition by arguing that those disadvantaged groups who possess low levels of any form of capital except for natural capital are more dependent on ecosystem services than those with greater control of capital. The higher value of the overall IDES or sub-index represents the higher dependence on the corresponding ecosystem services, and thus the higher vulnerability to the degradation or decline of corresponding ecosystem services. The IDES system improves our understanding of human dependence on ecosystem services. It also provides insights into strategies for alleviating poverty, for targeting priority groups of conservation programs, and for managing risks and opportunities due to changes of ecosystem services at multiple scales.

  3. Going beyond the Millennium Ecosystem Assessment: an index system of human dependence on ecosystem services.

    Directory of Open Access Journals (Sweden)

    Wu Yang

    Full Text Available The Millennium Ecosystem Assessment (MA estimated that two thirds of ecosystem services on the earth have degraded or are in decline due to the unprecedented scale of human activities during recent decades. These changes will have tremendous consequences for human well-being, and offer both risks and opportunities for a wide range of stakeholders. Yet these risks and opportunities have not been well managed due in part to the lack of quantitative understanding of human dependence on ecosystem services. Here, we propose an index of dependence on ecosystem services (IDES system to quantify human dependence on ecosystem services. We demonstrate the construction of the IDES system using household survey data. We show that the overall index and sub-indices can reflect the general pattern of households' dependences on ecosystem services, and their variations across time, space, and different forms of capital (i.e., natural, human, financial, manufactured, and social capitals. We support the proposition that the poor are more dependent on ecosystem services and further generalize this proposition by arguing that those disadvantaged groups who possess low levels of any form of capital except for natural capital are more dependent on ecosystem services than those with greater control of capital. The higher value of the overall IDES or sub-index represents the higher dependence on the corresponding ecosystem services, and thus the higher vulnerability to the degradation or decline of corresponding ecosystem services. The IDES system improves our understanding of human dependence on ecosystem services. It also provides insights into strategies for alleviating poverty, for targeting priority groups of conservation programs, and for managing risks and opportunities due to changes of ecosystem services at multiple scales.

  4. Shallow Horizontal GCHP Effectiveness in Arid Climate Soils

    Science.gov (United States)

    North, Timothy James

    Ground coupled heat pumps (GCHPs) have been used successfully in many environments to improve the heating and cooling efficiency of both small and large scale buildings. In arid climate regions, such as the Phoenix, Arizona metropolitan area, where the air condi-tioning load is dominated by cooling in the summer, GCHPs are difficult to install and operate. This is because the nature of soils in arid climate regions, in that they are both dry and hot, renders them particularly ineffective at dissipating heat. The first part of this thesis addresses applying the SVHeat finite element modeling soft-ware to create a model of a GCHP system. Using real-world data from a prototype solar-water heating system coupled with a ground-source heat exchanger installed in Menlo Park, California, a relatively accurate model was created to represent a novel GCHP panel system installed in a shallow vertical trench. A sensitivity analysis was performed to evaluate the accuracy of the calibrated model. The second part of the thesis involved adapting the calibrated model to represent an ap-proximation of soil conditions in arid climate regions, using a range of thermal properties for dry soils. The effectiveness of the GCHP in the arid climate region model was then evaluated by comparing the thermal flux from the panel into the subsurface profile to that of the prototype GCHP. It was shown that soils in arid climate regions are particularly inefficient at heat dissipation, but that it is highly dependent on the thermal conductivity inputted into the model. This demonstrates the importance of proper site characterization in arid climate regions. Finally, several soil improvement methods were researched to evaluate their potential for use in improving the effectiveness of shallow horizontal GCHP systems in arid climate regions.

  5. Solar Radiation at Surface for Typical Cities in the Arid and Semi-Arid Area in Xinjiang, China Based on Satellite Observation

    Science.gov (United States)

    Sihua, Fang; Haichen, Liu; Jiamin, Huang; Yunqi, Zhang; Jun, Hu; Yonghang, Chen; Yanming, Kang; Xue, Wang; Chengjie, Huang

    2017-05-01

    Xinjiang, a region of China with arid and semi-arid areas, has abundant solar incidence with 166.5×104 km2 and diverse underlying surface. The meager number of surface radiation observatories cannot meet the need for efficient exploration of solar energy. In this study we classified Xinjiang into three regions: southern Xinjiang, northern Xinjiang and Tu-Ha region and applied satellite data to provide the surface solar radiation’s temporal distribution for 10 typical cities. The study is focused on seasonal, annual and variations of all sky downward shortwave radiation flux at surface based on 24-year satellite dataset GEWEX-SRB from the WCRP/GEWEX (World Climate Research Program/Global Energy and Water Cycle Experiment) from 1984 to 2007. The results are as follows. In general, the monthly average solar radiation flux for the cities in the Tu-Ha region was the largest followed by the south Xinjiang and northern Xinjiang. The solar radiation in the most northern cities were less than 150.0 W/m2 in winter, the minimum is 138.7 W/m2, while the other cities were greater than 150.0 W/m2. The maximum of monthly solar flux for the Tu-Ha region, southern and northern Xinjiang was 400.0 W/m2.

  6. Pliocene-pleistocene evolution of tropical aridity

    Energy Technology Data Exchange (ETDEWEB)

    Menocal, P.B. de.

    1992-01-01

    This research tries to determine the nature and origin of low-latitude terrestrial climate variability prior to and after the rapid expansion of high-latitude ice sheets near 2.4 Myr to understand the interactions between high- and low-latitude climate systems since the late Pliocene (ca. 3.5 Myr). Records of eolian dust variability were reconstructed from wholecore magnetic susceptibility data at Ocean Drilling Project Site 661 in the eastern equatorial Atlantic and Site 721 on the Owen Ridge in the Arabian Sea. Susceptibility is a rapidly-measured and conservative indicator of terrigenous (eolian) variations at both sites and correlations were used to construct well-dated, composite sequences extending to 3.5 Myr. Evolutive spectral analysis of the two susceptibility records demonstrate that prior to 2.4 Myr both eolian records are dominated by variance at the 23-19 kyr precessional periodicities, whereas after 2.4 Myr the records exhibit strong increases in 41 kyr power. Dominant 23- 19 kyr variations at Site 721 extend from 2.4 Myr to at least the late Miocene (ca. 6 Myr). The increase in 41 kyr power after 2.4 Myr and the subsequent increase in 100 kyr power after 0.7 Myr reflect the onset of glacial aridity in African and Arabian dust source areas. We also present a 0.9 Myr record of eolian accumulation from ODP Site 663 in the tropical Atlantic; concentrations of two terrestrial eolian components, opal phytoliths (grass cuticles) and freshwater diatom (Melosira) valves from desiccated lake beds, were also measured. General circulation model sensitivity tests were used to examine physical linkages between high and low latitude climate, demonstrating that the African and Asian monsoon circulations are very responsive to precessional insolation forcing in the absence of significant ice volume variability. However, full glacial ice cover caused significant precipitation and temperature decreases in monsoon dust source areas in Arabia and northeast Africa.

  7. BUSINESS ECOSYSTEMS VS BUSINESS DIGITAL ECOSYSTEMS

    Directory of Open Access Journals (Sweden)

    Marinela Lazarica

    2006-05-01

    Full Text Available E-business is often described as the small organisations’ gateway to global business and markets. The adoption of Internet-based technologies for e-business is a continuous process, with sequential steps of evolution. The latter step in the adoption of Internet-based technologies for business, where the business services and the software components are supported by a pervasive software environment, which shows an evolutionary and self-organising behaviour are named digital business ecosystems. The digital business ecosystems are characterized by intelligent software components and services, knowledge transfer, interactive training frameworks and integration of business processes and e-government models.

  8. Using Digital Repeat Photography to Link Vegetative Phenology and Carbon Fluxes to Biotic and Abiotic Drivers in Three Semi-arid Systems (New Mexico, USA)

    Science.gov (United States)

    Hallmark, A.; Litvak, M. E.; Collins, S. L.

    2015-12-01

    Arid and semi-arid ecosystems account for over 45% of global land cover. While mean annual carbon uptake in these ecosystems is relatively low, aridlands collectively store a significant amount of carbon. There is high inter- and intra-annual variability of plant growth in aridlands, depending largely on the timing and size of rainfall events. This variation is also of great significance, as the variation in annual semi-aridland carbon uptake accounts for ~39% of the inter-annual variability of the global terrestrial carbon sink, the largest percentage of any land cover type. Although arid and semi-arid ecosystems are of global importance, they are understudied. To better understand the drivers and variability of carbon uptake in these critical ecosystems, we utilize a six-year record of digital images (45,000+ images), carbon flux and meteorological data, soil water content, and associated ecological measurements from three eddy covariance tower sites in central New Mexico. These sites include a Chihuahuan Desert/short-grass Plains grassland site, and post-fire successional grassland site, and a creosote-encroached shrubland site, each of which have unique species compositions, carbon fluxes, and reactions to disturbance and resource addition. All images used are co-registered and corrected for radial lens distortions (when necessary) and greenness indices (2GRBi, gcc, and/or NDVI) are calculated for each scene's overall "canopy" and for individual species and plant functional types therein. At all three sites, camera-derived greenness is correlated to measured carbon uptake with fine resolution (R2 up to 0.8), capturing temporal and spatial variation usually not seen in satellite-based imagery. At sites with lower LAI, species-specific ROI's were more correlated to the site's measured carbon flux across shorter time scales. Understanding the biota comprising each image and its contribution to changing scene greenness at different times of year can lead to more

  9. Bioactivity of arid region honey: an in vitro study.

    Science.gov (United States)

    Hilary, Serene; Habib, Hosam; Souka, Usama; Ibrahim, Wissam; Platat, Carine

    2017-03-29

    Antioxidant and anti-inflammatory properties of honey have been largely recognized by various studies. Almost all of the potential benefits are associated with polyphenol content. Honey varieties from the arid region are reported to be rich in polyphenols, but data related to its bioactivity in vitro is greatly lacking. This study aimed at establishing the antioxidant and anti-inflammatory properties of arid region honey. Four honey varieties from arid region (H1, H2, H3, and H4) and two popular non-arid region honey (H5 and H6) were tested in vitro in this study. The erythrocyte membrane protection effect of honey varieties were measured by hemolysis assay after exposing erythrocytes to a peroxide generator. The subsequent production of MDA (malondialdehyde) content in erythrocytes was measured. Immunomodulatory effect of the honey varieties was tested in prostate cancer cells PC-3 and PBMC (peripheral blood mononuclear cells) by measuring the IL-6 (interleukin 6) and NO (nitric oxide) levels in cell culture supernatant after incubation with the honey varieties. PC-3 cell viability was assessed after incubation with honey varieties for 24 h. Arid region honey exhibited superior erythrocyte membrane protection effect with H4 measuring 1.3 ± 0.042mMTE/g and H2 measuring 1.122 ± 0.018mMTE/g. MDA levels were significantly reduced by honey samples, especially H4 (20.819 ± 0.63 nmol/mg protein). We observed a significant decrease in cell population in PC-3 after 24 h in culture on treatment with honey. A moderate increase in NO levels was observed in both cultures after 24 h at the same time levels of IL-6 were remarkably reduced by honey varieties. The results demonstrate the antioxidant effect of arid region honey due to its erythrocyte membrane protection effect and subsequent lowering of oxidative damage as evident from lower levels of lipid peroxidation byproduct MDA. Arid region honey varieties were as good as non-arid region types at decreasing

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

    Energy Technology Data Exchange (ETDEWEB)

    W. K. Ostler

    2002-10-01

    establishing project objectives, scheduling, budgeting, and selecting cost-effective techniques. Reclamation techniques include sections describing: (1) erosion control (physical, chemical, and biological), (2) site preparation, (3) soil amendments, (4) seeding, (5) planting, (6) grazing and weed control, (7) mulching, (8) irrigation, and (9) site protection. Each section states the objectives of the technique, the principles, an in-depth look at the techniques, and any special considerations as it relates to DoD or DOE lands. The need for monitoring and remediation is described to guide users in monitoring reclamation efforts to evaluate their cost-effectiveness. Costs are provided for the proposed techniques for the major deserts of the southwestern U.S. showing the average and range of costs. A set of decision tools are provided in the form of a flow diagram and table to guide users in selecting effective reclamation techniques to achieve mitigation objectives. Recommendations are provided to help summarize key reclamation principles and to assist users in developing a successful program that contributes to sustainable uses of DoD and DOE lands. The users manual is helpful to managers in communicating to installation management the needs and consequences of training decisions and the costs required to achieve successful levels of sustainable use. This users manual focuses on the development of new reclamation techniques that have been implemented at the National Training Center at Fort Irwin, California, and are applicable to most arid land reclamation efforts.

  11. Achieve a Better Understanding of Cloud and Precipitation Processes for the Promotion of Water Security in Arid and Semi-Arid Regions

    Science.gov (United States)

    Farrah, S.; Al Yazidi, O.

    2016-12-01

    The UAE Research Program for Rain Enhancement Science (UAEREP) is an international research initiative designed to advance the science and technology of rain enhancement. It comes from an understanding of the needs of countries suffering from scarcity of fresh water, and its will to support innovation globally. The Program focuses on the following topics: Climate change, Climate modelling, Climatology, Atmospheric physics, Atmospheric dynamics, Weather modification, Cloud physics, Cloud dynamics, Cloud seeding, Weather radars, Dust modelling, Aerosol physics , Aerosol chemistry, Aerosol/cloud interactions, Water resources, Physics, Numerical modelling, Material science, Nanotechnology, Meteorology, Hydrology, Hydrogeology, Rocket technology, Laser technology, Water sustainability, Remote sensing, Environmental sciences... In 2015, three research teams from Japan, Germany and the UAE led by Prof. Masataka Murakami, Volker Wulfmeyer and Linda Zou have been respectively awarded. Together, they are addressing the issue of water security through innovative ideas: algorithms and sensors, land cover modification, and nanotechnologies to accelerate condensation. These three projects are undergoing now with extensive research and progresses. This session will be an opportunity to present their latest results as well as to detail the evolution of research in rain enhancement. In 2016 indeed, the Program saw a remarkable increase in participation, with 91 pre-proposals from 398 scientists, researchers and technologists affiliated to 180 institutes from 45 countries. The projects submitted are now focusing on modelling to predict weather, autonomous vehicles, rocket technology, lasers or new seeding materials… The science of rain enhancement offers considerable potential in terms of research, development and innovation. Though cloud seeding has been pursued since the late 1940s, it has been viewed as a relatively marginal field of interest for scientists. This benign neglect

  12. Alterations in flowering strategies and sexual allocation of Caragana stenophylla along a climatic aridity gradient

    Science.gov (United States)

    Xie, Lina; Guo, Hongyu; Ma, Chengcang

    2016-01-01

    Plant can alter reproductive strategies for adaptation to different environments. However, alterations in flowering strategies and sexual allocation for the same species growing in different environments still remain unclear. We examined the sexual reproduction parameters of Caragana stenophylla across four climatic zones from semi-arid, arid, very arid, to intensively arid zones in the Inner Mongolia Steppe, China. Under the relatively favorable climatic conditions of semi-arid zone, C. stenophylla took a K-strategy for flowering (fewer but bigger flowers, and higher seed set). In contrast, under the harsher climatic conditions of intensively arid zone, C. stenophylla took an r-strategy for flowering (more but smaller flowers, and lower seed set). In arid and very arid zones, C. stenophylla exhibited intermediate flowering strategies between K- and r-strategies. In semi-arid, arid and very arid zones, sexual allocation and sexual allocation efficiency (SAE) of C. stenophylla were high, and the population recruitment might be mainly through sexual reproduction; in intensively arid zone, however, sexual allocation and SAE were very low, seed production was very limited, and clonal reproduction might compensate for the decrease in sexual reproduction. Our results suggested that C. stenophylla adapted to the climatic aridity gradient by alterations in flowering strategies and reproductive allocation. PMID:27628093

  13. 78 FR 50030 - Implementation of New Gulf Coast Ecosystem Restoration Science, Observation, Monitoring, and...

    Science.gov (United States)

    2013-08-16

    ... INFORMATION CONTACT: Russ Beard, Acting Program Director, Gulf Coast Ecosystem Restoration Science... Space Center, MS 39529. SUPPLEMENTARY INFORMATION: I. Introduction The Resources and Ecosystem... science investments will evolve over time, adapting to changing information and knowledge. As noted...

  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. Competition in the Mashup Ecosystem

    Directory of Open Access Journals (Sweden)

    Amanda Shiga

    2011-01-01

    Full Text Available Mashups combine data from multiple sources to create innovative web applications. Data providers gain compelling advantages in offering an open application programming interface (API, but face a competitive environment where growth occurs by virtue of developers' independent choices and where competitors are also complementors. This article explores the nature of competition within the mashup ecosystem by focusing on competitive actions taken by API providers and their link to mashup network structure. The resulting insights help entrants and incumbents refine their competitive strategies within this complex and unique environment.

  17. CO2 and fire influence tropical ecosystem stability in response to climate change.

    Science.gov (United States)

    Shanahan, Timothy M; Hughen, Konrad A; McKay, Nicholas P; Overpeck, Jonathan T; Scholz, Christopher A; Gosling, William D; Miller, Charlotte S; Peck, John A; King, John W; Heil, Clifford W

    2016-07-18

    Interactions between climate, fire and CO2 are believed to play a crucial role in controlling the distributions of tropical woodlands and savannas, but our understanding of these processes is limited by the paucity of data from undisturbed tropical ecosystems. Here we use a 28,000-year integrated record of vegetation, climate and fire from West Africa to examine the role of these interactions on tropical ecosystem stability. We find that increased aridity between 28-15 kyr B.P. led to the widespread expansion of tropical grasslands, but that frequent fires and low CO2 played a crucial role in stabilizing these ecosystems, even as humidity changed. This resulted in an unstable ecosystem state, which transitioned abruptly from grassland to woodlands as gradual changes in CO2 and fire shifted the balance in favor of woody plants. Since then, high atmospheric CO2 has stabilized tropical forests by promoting woody plant growth, despite increased aridity. Our results indicate that the interactions between climate, CO2 and fire can make tropical ecosystems more resilient to change, but that these systems are dynamically unstable and potentially susceptible to abrupt shifts between woodland and grassland dominated states in the future.

  18. Network Models of Entrepreneurial Ecosystems in Developing Economies

    Science.gov (United States)

    2014-01-01

    interesting insights: • The Military and Religion Roles have no impact on this ecosystem . • The Self (an entrepreneur can access the necessary resources...Technical Report 15-004 Network Models of Entrepreneurial Ecosystems in Developing Economies Daniel Evans Louis Boguchwal...Entrepreneurial Ecosystems in Developing Economies 5b. GRANT NUMBER n/a 5c. PROGRAM ELEMENT NUMBER n/a 6. AUTHOR(S) Daniel Evans and Louis

  19. Moroccan Mountains: Forest Ecosystems and Biodiversity Conservation Strategies

    OpenAIRE

    Mohammed Sghir Taleb

    2016-01-01

    Forest ecosystems in Morocco are subject increasingly to natural and human pressures. Conscious of this problem, Morocco set a strategy that focuses on programs of in-situ and ex-situ biodiversity conservation. This study is the result of a synthesis of various existing studies on biodiversity and forest ecosystems. It gives an overview of Moroccan mountain forest ecosystems and flora diversity. It also focuses on the efforts made by Morocco to conserve and sustainably manage biodiversity.

  20. Ecosystem approach in education

    Science.gov (United States)

    Nabiullin, Iskander

    2017-04-01

    Environmental education is a base for sustainable development. Therefore, in our school we pay great attention to environmental education. Environmental education in our school is based on ecosystem approach. What is an ecosystem approach? Ecosystem is a fundamental concept of ecology. Living organisms and their non-living environments interact with each other as a system, and the biosphere planet functions as a global ecosystem. Therefore, it is necessary for children to understand relationships in ecosystems, and we have to develop systems thinking in our students. Ecosystem approach and systems thinking should help us to solve global environmental problems. How do we implement the ecosystem approach? Students must understand that our biosphere functions as a single ecosystem and even small changes can lead to environmental disasters. Even the disappearance of one plant or animal species can lead to irreversible consequences. So in the classroom we learn the importance of each living organism for the nature. We pay special attention to endangered species, which are listed in the Red Data List. Kids are doing projects about these organisms, make videos, print brochures and newspapers. Fieldwork also plays an important role for ecosystem approach. Every summer, we go out for expeditions to study species of plants and animals listed in the Red Data List of Tatarstan. In class, students often write essays on behalf of any endangered species of plants or animals, this also helps them to understand the importance of each living organism in nature. Each spring we organise a festival of environmental projects among students. Groups of 4-5 students work on a solution of environmental problems, such as water, air or soil pollution, waste recycling, the loss of biodiversity, etc. Participants shoot a clip about their project, print brochures. Furthermore, some of the students participate in national and international scientific Olympiads with their projects. In addition to

  1. 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.

  2. Quantification of the aridity process in South-Western Romania.

    Science.gov (United States)

    Peptenatu, Daniel; Sîrodoev, Igor; Pravalie, Remus

    2013-05-24

    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.

  3. 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)

  4. Integrated catchment modelling in a Semi-arid area

    CSIR Research Space (South Africa)

    Bugan, Richard DH

    2010-09-01

    Full Text Available optimization, statistical and sensitivity analyses are also included in the model. exAMple oF ApplIcAtIon the J2000 process model was applied to the Sandspruit seasonal tributary of the Berg river, in the semi-arid climate (300-400 mm a-1 precipitation... Catchment Modelling in a Semi-arid Area RDH BUGAN AND NZ JOVANOVIC CSIR Natural Resources and the Environment, PO Box 320, Stellenbosch, 7599, South Africa Email: rbugan@csir.co.za – www.csir.co.za IntroductIon Water management in South Africa...

  5. 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

  6. Observing Mean Annual Mediterranean Maquis Ecosystem Respiration

    Science.gov (United States)

    Marras, S.; Bellucco, V.; Mereu, S.; Sirca, C.; Spano, D.

    2014-12-01

    In semi arid ecosystems, extremely low Soil Water Content (SWC) values may limit ecosystem respiration (Reco) to the point of hiding the typical exponential response of respiration to temperature. This work is aimed to understand and model the Reco of an evergreen Mediterranean maquis ecosystem and to estimate the contribution of soil CO2 efflux to Reco. The selected site is located in the center of the Mediterranean sea in Sardinia (Italy). Mean annual precipitation is 588 mm and mean annual temperature is 15.9 °C. Vegetation cover is heterogeneous: 70% covered by shrubs and 30% of bare soil. Net Ecosystem Exchange (NEE) is monitored with an Eddy Covariance (EC) tower since April 2004. Soil collars were placed underneath the dominant species (Juniperus phoenicea and Pistacia lentiscus) and over the bare soil. Soil CO2 efflux was measured once a month since April 2012. Soil temperature and SWC were monitored continuously at 5 cm depth in 4 different positions close to the soil collars. Six years of EC measurements (2005-2010) and two years of soil CO2 efflux (2012-2013) measurements were analysed. Reco was estimated from the measured EC fluxes at night after filtering for adequate turbulence (u* > 1.5). Reco measurements were then binned into 1°C intervals and median values were first fitted using the Locally Estimated Scatterplot Smoothing (LOESS) method (to determine the dominant trend of the experimental curve) Reco shows an exponential increase with air and soil temperature, until SWC measured at 0.2 m depth remains above 19% vol. Secondly, the coefficients of the selected Lloyd and Taylor (1994) were estimated through the nonlinear least square (nls) method: Rref (ecosystem respiration rate at a reference temperature of 10 °C was equal to 1.65 μmol m-2 s-1 and E0 (activation energy parameter that determines the temperature sensitivity) was equal to 322.46. In addition, bare and drier soils show a reduced response of measured CO2 efflux to increasing

  7. Development and implementation of a monitoring and information system to increase water use efficiency in arid and semi-arid areas in Limarí, Central Chile (WEIN

    Directory of Open Access Journals (Sweden)

    E. Berger

    2016-10-01

    Full Text Available The project WEIN was funded by the Federal Ministry of Education and Research (BMBF | Berlin, Germany in the framework of the high-tech strategy of Germany's program "KMU-Innovativ". The project started in 2012 and was completed in 2014. In the scope of the project, an integrated system for analysis, monitoring and information at river basin level was developed, which provides relevant information for all stakeholders that are concerned with water resource issues. The main objective of the project was to improve water use efficiency and hence ensure the agricultural production in the region. The pilot region, in which this system was implemented, is the semi-arid Limarí basin in Northern Central Chile. One of the main parts of the project was the development and implementation of a web- and app-based irrigation water ordering and accounting system for local farmers.

  8. Development and implementation of a monitoring and information system to increase water use efficiency in arid and semi-arid areas in Limarí, Central Chile (WEIN)

    Science.gov (United States)

    Berger, Erich; Balmert, David; Richter, Jürgen

    2016-10-01

    The project WEIN was funded by the Federal Ministry of Education and Research (BMBF | Berlin, Germany) in the framework of the high-tech strategy of Germany's program "KMU-Innovativ". The project started in 2012 and was completed in 2014. In the scope of the project, an integrated system for analysis, monitoring and information at river basin level was developed, which provides relevant information for all stakeholders that are concerned with water resource issues. The main objective of the project was to improve water use efficiency and hence ensure the agricultural production in the region. The pilot region, in which this system was implemented, is the semi-arid Limarí basin in Northern Central Chile. One of the main parts of the project was the development and implementation of a web- and app-based irrigation water ordering and accounting system for local farmers.

  9. Millennium Ecosystem Assessment: MA Scenarios

    Data.gov (United States)

    National Aeronautics and Space Administration — The Millennium Ecosystem Assessment: MA Scenarios provide useful insight into the complex factors that drive ecosystem change, estimating the magnitude of regional...

  10. Dynamics of soil carbon and nitrogen stocks after afforestation in arid and semi-arid regions: A meta-analysis.

    Science.gov (United States)

    Liu, Xiang; Yang, Tao; Wang, Quan; Huang, Farong; Li, Lanhai

    2017-10-23

    Arid and semi-arid regions store approximately 27% of global soil organic carbon (SOC), thus playing an important role in the global carbon cycle. Although afforestation is widely used to achieve the goals of landscape protection and ecological restoration in these regions, its effects on the dynamics of SOC and total nitrogen (TN) stocks as well as the related controlling factors are still poorly understood. In this study, a meta-analysis was conducted by compiling results from published studies to evaluate the influences of afforestation on dynamics of SOC and TN stocks in mineral soils (0-30cm) in arid and semi-arid regions, and to examine whether the changes in SOC and TN stocks were influenced by prior land-use, planted tree species and plantation age. The results showed that overall, afforestation significantly increased SOC stock by 131% and TN stock by 88%. Prior land-use was found to be the most important factor that influenced the dynamics of SOC and TN stocks following afforestation. Significantly larger increases in SOC and TN stocks were observed after barren land afforestation in comparison to cropland and grassland afforestation. The accumulations in SOC and TN stocks after afforestation decreased in the following order: broadleaf deciduous forests>coniferous forests>broadleaf evergreen forests. However, significant differences in SOC and TN accumulations were only detected between broadleaf deciduous forests and broadleaf evergreen forests. Plantation age did not affect the dynamics of SOC and TN stocks after afforestation, mainly due to the rapid accumulations in SOC and TN after barren land afforestation. The results indicate that afforestation, especially on barren land with broadleaf deciduous species, provides substantial opportunities for SOC and TN sequestrations in arid and semi-arid regions. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Environmental gradients across wetland vegetation groups in the arid slopes of Western Alborz Mountains, N. Iran

    Directory of Open Access Journals (Sweden)

    Asghar Kamrani

    2011-01-01

    Full Text Available Mountain wetlands are unique ecosystems in the arid southern slopes of Alborz range, the second largest range in Iran. The spatial distribution characteristics of wetland vegetation in the arid region of the Alborz and the main factors affecting their distributional patterns were studied. A classification of vegetation and ecological characteristics were carried out using data extracted from 430 relevés in 90 wetland sites. The data were analyzed using Two Way Indicator Species Analysis (TWINSPAN and detrended correspondence analysis (DCA. The wetland vegetation of Alborz Mountain was classified into four large groups. The first vegetation group was calcareous rich vegetation, mainly distributed in the river banks and characterized by helophytes such as Bolboschoenus affinis as indicator species. The second group was saline transitional vegetation, distributed in the ecotone areas and dominated by Phragmites australis. The third vegetation group is wet meadow vegetation which mainly consists of geophytes, endemic and Irano-Turanian species, distributed in the higher altitudes. This vegetation is mainly characterized by indicator species such as Carex orbicularis, high level concentration of Fe2+ and percentage of organic matter in the soil. The fourth vegetation group is aquatic vegetation, distributed in the lakeshores. The aquatic group species are mainly hydrophytic such as Batrachium trichophyllum. The TWINSPAN vegetation groups could be also recognized in the DCA graphs and ecologically differentiated by ANOVA of studied variables. Four vegetation groups can be differentiated on two first axes of indirect ordination. There is a gradient of pH, EC and organic matter associated with altitude on the DCA diagram. Correlation analysis between the axes of DCA and environmental factors shows that altitude, soil texture and other dependant environmental variables (e.g. pH are the main environmental factors affecting the distribution of wetland

  12. International Arid Lands Consortium: Better land stewardship in water and watershed management

    Science.gov (United States)

    Peter F. Ffolliott; James T. Fisher; Menachem Sachs; Darrell W. DeBoer; Jeffrey O. Dawson; Timothy E. Fulbright; John Tracy

    2000-01-01

    The International Arid Lands Consortium (IALC) was established in 1990 to promote research, education, and training for the development, management, and restoration of arid and semi-arid lands throughout the world. One activity of IALC members and cooperators is to support research and development and demonstration projects that enhance management of these fragile...

  13. 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)

  14. File list: Oth.ALL.05.Arid3a.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.05.Arid3a.AllCell mm9 TFs and others Arid3a All cell types SRX520224,SRX520...225 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.ALL.05.Arid3a.AllCell.bed ...

  15. File list: Oth.PSC.05.Arid3a.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.PSC.05.Arid3a.AllCell mm9 TFs and others Arid3a Pluripotent stem cell SRX520224...,SRX520225 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.PSC.05.Arid3a.AllCell.bed ...

  16. File list: Oth.PSC.10.Arid3a.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.PSC.10.Arid3a.AllCell mm9 TFs and others Arid3a Pluripotent stem cell SRX520224...,SRX520225 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.PSC.10.Arid3a.AllCell.bed ...

  17. File list: Oth.ALL.50.Arid3a.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.ALL.50.Arid3a.AllCell mm9 TFs and others Arid3a All cell types SRX520224,SRX520...225 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.ALL.50.Arid3a.AllCell.bed ...

  18. File list: Oth.PSC.20.Arid3a.AllCell [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.PSC.20.Arid3a.AllCell mm9 TFs and others Arid3a Pluripotent stem cell SRX520224...,SRX520225 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/Oth.PSC.20.Arid3a.AllCell.bed ...

  19. Effects of groundwater abstraction on two keystone tree species in an arid savanna national park.

    Science.gov (United States)

    Shadwell, Eleanor; February, Edmund

    2017-01-01

    In arid systems with no surface water, deep boreholes in ephemeral river beds provide for humans and animals. With continually increasing infrastructure development for tourism in arid wildlife parks such as the Kgalagadi Transfrontier Park in southern Africa, we ask what effects increased abstraction may have on large trees. Large trees in arid savannas perform essential ecosystem services by providing food, shade, nesting sites and increased nutrients for many other plant and animal species and for this are regarded as keystone species. We determine seasonal fluctuations in the water table while also determining the water source for the dominant large tree species in the Auob and Nossob rivers in the Park. We also determine the extent to which these trees are physiologically stressed using leaf δ(13)C, xylem pressure potentials, specific leaf area and an estimate of canopy death. We do this both upstream and downstream of a low water use borehole in the Auob River and a high water use borehole in the Nossob River. Our results show that the trees are indeed using deep groundwater in the wet season and that this is the same water used by people. In the dry season, trees in the Auob downstream of the active borehole become detached from the aquifer and use more isotopically enriched soil water. In the Nossob in the dry season, all trees use isotopically enriched soil water, and downstream of the active borehole use stomatal regulation to maintain leaf water potentials. These results suggest that trees in the more heavily utilised Nossob are under more water stress than those trees in the Auob but that trees in both rivers demonstrate physiological adaptation to the changes in available water with smaller heavier leaves, no significant canopy dieback and in the dry season in the Nossob stomatal regulation of leaf water potentials. An increase in abstraction of groundwater particularly at the Nossob borehole may cause an additional draw down of the water table adding

  20. Revisiting software ecosystems research

    DEFF Research Database (Denmark)

    Manikas, Konstantinos

    2016-01-01

    ‘Software ecosystems’ is argued to first appear as a concept more than 10 years ago and software ecosystem research started to take off in 2010. We conduct a systematic literature study, based on the most extensive literature review in the field up to date, with two primarily aims: (a) to provide...... an updated overview of the field and (b) to document evolution in the field. In total, we analyze 231 papers from 2007 until 2014 and provide an overview of the research in software ecosystems. Our analysis reveals a field that is rapidly growing both in volume and empirical focus while becoming more mature...... from evolving. We propose means for future research and the community to address them. Finally, our analysis shapes the view of the field having evolved outside the existing definitions of software ecosystems and thus propose the update of the definition of software ecosystems....

  1. Total Ecosystem Carbon Stock

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Total ecosystem carbon includes above- and below-ground live plant components (such as leaf, branch, stem and root), dead biomass (such as standing dead wood, down...

  2. Privacy driven internet ecosystem

    OpenAIRE

    Trinh, Tuan Anh; Gyarmati, Laszlo

    2012-01-01

    The dominant business model of today's Internet is built upon advertisements; users can access Internet services while the providers show ads to them. Although significant efforts have been made to model and analyze the economic aspects of this ecosystem, the heart of the current status quo, namely privacy, has not received the attention of the research community yet. Accordingly, we propose an economic model of the privacy driven Internet ecosystem where privacy is handled as an asset that c...

  3. Stakeholder Values and Ecosystems

    OpenAIRE

    Sveinsdottir, Thordis; Wessels, Bridgette; Smallwood, Rod; Linde, Peter; Kalla, Vasso; Tsoukala, Victoria; Sondervan, Jeroen

    2013-01-01

    This report is the deliverable for Work Package 1 (WP1), Stakeholder Values and Ecosystems, of the EU FP7 funded project RECODE (Grant Agreement No: 321463), which focuses on developing Policy Recommendations for Open Access to Research Data in Europe. WP1 focuses on understanding stakeholder values and ecosystems in Open Access, dissemination and preservation in the area of scientific and scholarly data (thus not government data). The objectives of this WP are as follows: • Identify and map ...

  4. Local disease-ecosystem-livelihood dynamics: reflections from comparative case studies in Africa.

    Science.gov (United States)

    Leach, Melissa; Bett, Bernard; Said, M; Bukachi, Salome; Sang, Rosemary; Anderson, Neil; Machila, Noreen; Kuleszo, Joanna; Schaten, Kathryn; Dzingirai, Vupenyu; Mangwanya, Lindiwe; Ntiamoa-Baidu, Yaa; Lawson, Elaine; Amponsah-Mensah, Kofi; Moses, Lina M; Wilkinson, Annie; Grant, Donald S; Koninga, James

    2017-07-19

    This article explores the implications for human health of local interactions between disease, ecosystems and livelihoods. Five interdisciplinary case studies addressed zoonotic diseases in African settings: Rift Valley fever (RVF) in Kenya, human African trypanosomiasis in Zambia and Zimbabwe, Lassa fever in Sierra Leone and henipaviruses in Ghana. Each explored how ecological changes and human-ecosystem interactions affect pathogen dynamics and hence the likelihood of zoonotic spillover and transmission, and how socially differentiated peoples' interactions with ecosystems and animals affect their exposure to disease. Cross-case analysis highlights how these dynamics vary by ecosystem type, across a range from humid forest to semi-arid savannah; the significance of interacting temporal and spatial scales; and the importance of mosaic and patch dynamics. Ecosystem interactions and services central to different people's livelihoods and well-being include pastoralism and agro-pastoralism, commercial and subsistence crop farming, hunting, collecting food, fuelwood and medicines, and cultural practices. There are synergies, but also tensions and trade-offs, between ecosystem changes that benefit livelihoods and affect disease. Understanding these can inform 'One Health' approaches towards managing ecosystems in ways that reduce disease risks and burdens.This article is part of the themed issue 'One Health for a changing world: zoonoses, ecosystems and human well-being'. © 2017 The Authors.

  5. [Ecosystem services valuation of Qinghai Lake].

    Science.gov (United States)

    Jiang, Bo; Zhang, Lu; Ouyang, Zhi-yun

    2015-10-01

    Qinghai Lake is the largest inland and salt water lake in China, and provides important ecosystem services to beneficiaries. Economic valuation of wetland ecosystem services from Qinghai Lake can reveal the direct contribution of lake ecosystems to beneficiaries using economic data, which can advance the incorporation of wetland protection of Qinghai Lake into economic tradeoffs and decision analyses. In this paper, we established a final ecosystem services valuation system based on the underlying ecological mechanisms and regional socio-economic conditions. We then evaluated the eco-economic value provided by the wetlands at Qinghai Lake to beneficiaries in 2012 using the market value method, replacement cost method, zonal travel cost method, and contingent valuation method. According to the valuation result, the total economic values of the final ecosystem services provided by the wetlands at Qinghai Lake were estimated to be 6749.08 x 10(8) yuan RMB in 2012, among which the value of water storage service and climate regulation service were 4797.57 x 10(8) and 1929.34 x 10(8) yuan RMB, accounting for 71.1% and 28.6% of the total value, respectively. The economic value of the 8 final ecosystem services was ranked from greatest to lowest as: water storage service > climate regulation service > recreation and tourism service > non-use value > oxygen release service > raw material production service > carbon sequestration service > food production service. The evaluation result of this paper reflects the substantial value that the wetlands of Qinghai Lake provide to beneficiaries using monetary values, which has the potential to help increase wetland protection awareness among the public and decision-makers, and inform managers about ways to create ecological compensation incentives. The final ecosystem service evaluation system presented in this paper will offer guidance on separating intermediate services and final services, and establishing monitoring programs for

  6. Pathways to Resilience in Semi-Arid Economies | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    How can populations become resilient to climate change while pursuing economic growth? This question is at the heart of a research project designed to support climate-resilient economic development in semi-arid lands. It will do so by addressing the conditions for economic growth and considering the needs of women ...

  7. Pathways to Resilience in Semi-Arid Economies (PRISE)

    International Development Research Centre (IDRC) Digital Library (Canada)

    rlarbey

    should adaptation be integrated into economic development policies? 3. What are the new opportunities for and threats to markets in SALs arising from climate change in semi-arid areas, and how is the private sector adapting? 4. How do natural resource management policies condition vulnerability and resilience in.

  8. Predicting the breeding success of large raptors in arid southern ...

    African Journals Online (AJOL)

    Raptors are often priorities for conservation efforts and breeding success is a target measure for assessing their conservation status. The breeding success of large raptors in arid southern Africa is thought to be higher in years of high rainfall. While this correlation has been found in several studies, it has not yet been shown ...

  9. 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.

  10. Characterization of lactic acid bacteria isolated from Algerian arid ...

    African Journals Online (AJOL)

    Diversity and density of lactic acid bacteria isolated from Algerian raw goats\\' milk in arid zones were studied by determination of morphological, cultural, physiological and biochemical characteristics. 206 lactic acid bacterial strains were isolated, with 115 of them belonging to lactic acid cocci and others to the genus, ...

  11. Adaptation at Scale in Semi-Arid Regions | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    People living in Africa and South Asia's semi-arid regions face challenges that hinder their economic growth and development. This project seeks to find proactive, longer-term approaches to climate change adaptation in these vulnerable regions, while helping locals manage existing risks. Short-term focus must shift. So far ...

  12. 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

  13. Aboveground biomass production of a semi-arid southern African ...

    African Journals Online (AJOL)

    Following a field campaign to determine the species composition, canopy cover, aboveground annual production and leaf area index (LAI) of the semi-arid savanna of north-western Namibia, we present a production model that can be used by graziers to determine the livestock carrying capacity. The model predicts the ...

  14. Mixed livestock grazing in diverse temperate and semi-arid ...

    African Journals Online (AJOL)

    Concerns for product quality, uniformity and continuity and for animal welfare will increasingly drive production processes. In this paper, the potential of mixed grazing for higher output of quality animal products, within these constraints, is assessed under both temperate and semi-arid conditions. Complementary ...

  15. Extremely arid soils of the Ili Depression in Kazakhstan

    Science.gov (United States)

    Lebedeva, M. P.; Gerasimova, M. I.; Golovanov, D. L.; Yamnova, I. A.

    2015-01-01

    On the basis of macro- and micromorphological and analytical studies of extremely arid soils of the Ili Depression in Kazakhstan, a comparative analysis of pedogenetic processes shaping these soils on piedmont plains of different ages and heights is performed. The types of soil horizons and their combinations are analyzed in the context opf modern Russian and international soil classification systems. The genesis of extremely arid soils is controlled by the climatic conditions and by their geomorphic position on alluvial fans of piedmont plains. The following processes are diagnosed in these soils: soil crusting with vesicular porosity, the development of desert pavements with rock varnish, rubification, surface salinization, and iron depletion around the pores. It is suggested that the initial factor-based name (extremely arid) of these soils can be replaced by the name vesicular-crusty soils with the corresponding AKL diagnostic horizon, which is more consistent with the principles of substantive-genetic classification systems. In order to determine the classification position of these soils in terms of the new Russian soil classification system, new diagnostic horizons—AKL and CS—have to be introduced in this system. According to the WRB classification, the studied soils belong to the group of Gypsisols; the soil with strong salinization fits the criteria of the group of Solonchaks. A qualifier [yermic] is to be added to reflect the development of desert pavement and vesicular layer under extreme arid conditions.

  16. ESTIMATING LEAF AREA INDEX FOR AN ARID REGION USING ...

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    Leaf Area Index (LAI) is one of the important crop parameters that can be used to assess crop conditions or drought severity. Estimating LAI for arid regions presents challenge due to the high spatial variability in precipitation and in crop canopies found in such regions. In this study, spectral reflectance of pearl millet was ...

  17. Reproductive performance of two sow lines under arid climatic ...

    African Journals Online (AJOL)

    Reproductive performance of two sow lines under arid climatic conditions. ... Abstract. Data (n = 4836) from a pig company in Namibia recorded over the period 2002 – 2007 were analysed to: (i) compare performance of two sow lines for the age at first ... LTB increased by 10.9 ± .1 piglets per unit increase in parity at culling.

  18. Assessment of microbial diversity under arid plants by culture ...

    African Journals Online (AJOL)

    Dr. R. K. Jain

    2013-10-02

    Oct 2, 2013 ... (0.534). Both culture- dependent and culture-independent methods indicated that in arid crops, microbial diversity is more ... MATERIALS AND METHODS. Sample collection. Three soil samples each from rhizosphere of ker and pearl millet along with adjacent non-rhizospheric areas of different location of.

  19. Paclobutrazol biodegradation in unsaturated soil in the Semi-Arid ...

    African Journals Online (AJOL)

    Paclobutrazol (PBZ) is a plant growth regulator, increasing flowe ring and yield that is widely used in mango cultivation in the semi-arid northeastern Brazil. PBZ remains active in the soil for several years. However, it can severely affect the growth and development of subsequent crops, mainly by reducing vegetative vigor.

  20. THE SURFACE WATER STORAGE PROBLEM IN ARID REGIONS:

    African Journals Online (AJOL)

    H. Benfetta

    2017-09-01

    Sep 1, 2017 ... This dam is located in an arid zone where water resources are becoming increasingly scarce. It is situated 5 km from the ... /year), while dead storage accounts for 4.6 million m. 3 .... These data highlight a clear evaporation gradient: in the coastal zone (up to 50 km from the sea) annual evaporation is <0.5 ...

  1. 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

  2. DRIFT-ARID: Application of a method for environmental water ...

    African Journals Online (AJOL)

    2016-07-03

    Jul 3, 2016 ... in a DRIFT-ARID Decision Support System (DSS) to determine the impact of five chosen development scenarios in the Mokolo River Catchment. An integrated ..... Left: Overlay of Geomorphological Zones, Macroreaches, Level II Ecoregions, and Runoff Potential Units (RPUs). Right: Natural Resource Units ...

  3. Salma Hegga: Identifying adaptation strategies for semi-arid regions ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2015-02-18

    Feb 18, 2015 ... Together with teams from Southern, Western, and Eastern Africa, and India, she is working to assess vulnerability and adaptation to climate change in semi-arid regions. The research aims to identify adaptation strategies in these areas and determine which are the most effective. This research will also ...

  4. Multilayer perceptron neural network for downscaling rainfall in arid ...

    Indian Academy of Sciences (India)

    rent and future climate is therefore very essential. (Huth et al. 2008). General circulation models (GCMs) ... studies have been conducted for downscaling rain- fall in the arid regions such as, the studies by Sen et al. ...... developed from statistical downscaling methods; www. ipcc-data.org/guidelines/dgm no2 v1 09 2004.pdf.

  5. Reservoir in a Semi-Arid Region of Kenya

    African Journals Online (AJOL)

    a catchment devoid of roads in semi-arid region. Introduction due to the torrential nature of the rains. Formanyyears ... study took place, underground reservoirs serve as the main source of water for both domestic and ... slope steepness and the widths ofthe drains along the roads on the catchment as well as the valley which ...

  6. ARID1A Is Essential for Endometrial Function during Early Pregnancy.

    Directory of Open Access Journals (Sweden)

    Tae Hoon Kim

    2015-09-01

    Full Text Available AT-rich interactive domain 1A gene (ARID1A loss is a frequent event in endometriosis-associated ovarian carcinomas. Endometriosis is a disease in which tissue that normally grows inside the uterus grows outside the uterus, and 50% of women with endometriosis are infertile. ARID1A protein levels were significantly lower in the eutopic endometrium of women with endometriosis compared to women without endometriosis. However, an understanding of the physiological effects of ARID1A loss remains quite poor, and the function of Arid1a in the female reproductive tract has remained elusive. In order to understand the role of Arid1a in the uterus, we have generated mice with conditional ablation of Arid1a in the PGR positive cells (Pgrcre/+Arid1af/f; Arid1ad/d. Ovarian function and uterine development of Arid1ad/d mice were normal. However, Arid1ad/d mice were sterile due to defective embryo implantation and decidualization. The epithelial proliferation was significantly increased in Arid1ad/d mice compared to control mice. Enhanced epithelial estrogen activity and reduced epithelial PGR expression, which impedes maturation of the receptive uterus, was observed in Arid1ad/d mice at the peri-implantation period. The microarray analysis revealed that ARID1A represses the genes related to cell cycle and DNA replication. We showed that ARID1A positively regulates Klf15 expression with PGR to inhibit epithelial proliferation at peri-implantation. Our results suggest that Arid1a has a critical role in modulating epithelial proliferation which is a critical requisite for fertility. This finding provides a new signaling pathway for steroid hormone regulation in female reproductive biology and furthers our understanding of the molecular mechanisms that underlie dysregulation of hormonal signaling in human reproductive disorders such as endometriosis.

  7. Influence of biological soil crusts at different successional stages in the implantation of biogeochemical cycles in arid and semiarid zones

    Science.gov (United States)

    Gil-Sotres, F.; Miralles, I.; Canton-Castilla, Y.; Domingo, F.; Leiros, M. C.; Trasar-Cepeda, C.

    2012-04-01

    Influence of biological soil crusts at different successional stages in the implantation of biogeochemical cycles in arid and semiarid zones I. Miralles1, F. Gil-Sotres2, Y. Cantón-Castilla3, F. Domingo1, M.C. Leirós2, C. Trasar-Cepeda4 1 Experimental Estation of Arid Zones (CSIC), E-04230 La Cañada de San Urbano, Almería, Spain. 2 Departamento Edafología y Química Agrícola, Grupo de Evaluación de la Calidad del Suelo, Unidad Asociada CSIC, Facultad de Farmacia, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain. 3 University of Almería, Departamento de Edafología y Química Agrícola, E-04230-La Cañada de San Urbano, Almería, Spain. 4 Departamento Bioquímica del Suelo, IIAG-CSIC, Apartado 122, E-15708 Santiago de Compostela, Spain. Crusts (BSCs) are formed by a close association between soil particles and cyanobacteria, algae, lichens, bryophytes and microfungi in varying proportions. Their habitat is within or immediately on top of the uppermost millimetres of the soil and are the predominant surface cover in arid and semiarid zones. Among the diverse functions developed by BSCs in the ecosystem (hydrology, erosion, soil properties, etc.), one of the most important is its role in nutrient cycling. Within arid and semiarid environments, BSCs have been termed 'mantles of fertility' being considered hotspots of biogeochemical inputs, fixing C, N and P above- and below-ground. However, there are differences in N and C fixation rates between BSCs types. Early successional BSCs, dominated by cyanobacterial species, fix lower quantities of C and N than mature BSCs dominated by lichens. Although the positive effects of BSCs on biogeochemical soil cycles are widely accepted, no previous studies have evaluated the activities of the enzymes involved in C, N and P cycles of BSCs and how they are affected by the successional stage of the BSC. In this work, performed in the Tabernas desert (SE Spain), we studied the hydrolase enzymes

  8. 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

  9. EnviroAtlas - Rare Ecosystems in the Conterminous United States

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset identifies rare ecosystems using base landcover data from the USGS GAP Analysis Program (Version 2, 2011) combined with landscape ecology...

  10. Monetary accounting of ecosystem services

    NARCIS (Netherlands)

    Remme, R.P.; Edens, Bram; Schröter, Matthias; Hein, Lars

    2015-01-01

    Ecosystem accounting aims to provide a better understanding of ecosystem contributions to the economy in a spatially explicit way. Ecosystem accounting monitors ecosystem services and measures their monetary value using exchange values consistent with the System of National Accounts (SNA). We

  11. 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)

  12. Recovery of microbial community structure and functioning after wildfire in semi-arid environments: optimising methods for monitoring and assessment

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Martini, Dylan; Erickson, Todd; Merritt, David; Dixon, Kingsley

    2015-04-01

    Introduction In semi-arid areas such as northern Western Australia, wildfires are a natural part of the environment and many ecosystems in these landscapes have evolved and developed a strong relationship with fire. Soil microbial communities play a crucial role in ecosystem processes by regulating the cycling of nutrients via decomposition, mineralization, and immobilization processes. Thus, the structure (e.g. soil microbial biomass) and functioning (e.g. soil microbial activity) of microbial communities, as well as their changes after ecosystem disturbance, can be useful indicators of soil quality and health recovery. In this research, we assess the impacts of fire on soil microbial communities and their recovery in a biodiverse semi-arid environment of Western Australia (Pilbara region). New methods for determining soil microbial respiration as an indicator of microbial activity and soil health are also tested. Methodology Soil samples were collected from 10 similar ecosystems in the Pilbara with analogous native vegetation, but differing levels of post-fire disturbance (i.e. 3 months, 1 year, 5, 7 and 14 years after wildfire). Soil microbial activity was measured with the Solvita test which determines soil microbial respiration rate based on the measurement of the CO2 burst of a dry soil after it is moistened. Soils were dried and re-wetted and a CO2 probe was inserted before incubation at constant conditions of 25°C during 24 h. Measurements were taken with a digital mini spectrometer. Microbial (bacteria and fungi) biomass and community composition were measured by phospholipid fatty acid analysis (PLFA). Results Immediately after the fire (i.e. 3 months), soil microbial activity and microbial biomass are similar to 14 years 'undisturbed' levels (53.18±3.68 ppm CO2-CO and 14.07±0.65 mg kg-1, respectively). However, after the first year post-fire, with larger plant productivity, microbial biomass and microbial activity increase rapidly, peaking after 5

  13. 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.

  14. Biogeochemical factors contributing to enhanced carbon storage following afforestation of a semi-arid shrubland

    Directory of Open Access Journals (Sweden)

    J. M. Grünzweig

    2007-10-01

    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. 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 (12% of total SOC. Our results suggest a role for increased N use efficiency, enhanced SOC protection and reduced decomposition rates in the large C sequestration potential following afforestation in semi-arid regions. These results are particularly relevant in light of persistent

  15. Soil bacterial and fungal community responses to nitrogen addition across soil depth and microhabitat in an arid shrubland

    Science.gov (United States)

    Mueller, Rebecca C.; Belnap, Jayne; Kuske, Cheryl R.

    2015-01-01

    Arid shrublands are stressful environments, typified by alkaline soils low in organic matter, with biologically-limiting extremes in water availability, temperature, and UV radiation. The widely-spaced plants and interspace biological soil crusts in these regions provide soil nutrients in a localized fashion, creating a mosaic pattern of plant- or crust-associated microhabitats with distinct nutrient composition. With sporadic and limited rainfall, nutrients are primarily retained in the shallow surface soil, patterning biological activity. We examined soil bacterial and fungal community responses to simulated nitrogen (N) deposition in an arid Larrea tridentata-Ambrosia dumosa field experiment in southern Nevada, USA, using high-throughput sequencing of ribosomal RNA genes. To examine potential interactions among the N application, microhabitat and soil depth, we sampled soils associated with shrub canopies and interspace biological crusts at two soil depths (0–0.5 or 0–10 cm) across the N-amendment gradient (0, 7, and 15 kg ha−1 yr−1). We hypothesized that localized compositional differences in soil microbiota would constrain the impacts of N addition to a microhabitat distribution that would reflect highly localized geochemical conditions and microbial community composition. The richness and community composition of both bacterial and fungal communities differed significantly by microhabitat and with soil depth in each microhabitat. Only bacterial communities exhibited significant responses to the N addition. Community composition correlated with microhabitat and depth differences in soil geochemical features. Given the distinct roles of soil bacteria and fungi in major nutrient cycles, the resilience of fungi and sensitivity of bacteria to N amendments suggests that increased N input predicted for many arid ecosystems could shift nutrient cycling toward pathways driven primarily by fungal communities.

  16. Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments

    Science.gov (United States)

    Jackson, W Andrew; Böhlke, John Karl; Andraski, Brian J.; Fahlquist, Lynne S.; Bexfield, Laura M.; Eckardt, Frank D.; Gates, John B.; Davila, Alfonso F.; McKay, Christopher P.; Rao, Balaji; Sevanthi, Ritesh; Rajagopalan, Srinath; Estrada, Nubia; Sturchio, Neil C.; Hatzinger, Paul B.; Anderson, Todd A.; Orris, Greta J.; Betancourt, Julio L.; Stonestrom, David A.; Latorre, Claudio; Li, Yanhe; Harvey, Gregory J.

    2015-01-01

    Natural perchlorate (ClO4−) is of increasing interest due to its wide-spread occurrence on Earth and Mars, yet little information exists on the relative abundance of ClO4− compared to other major anions, its stability, or long-term variations in production that may impact the observed distributions. Our objectives were to evaluate the occurrence and fate of ClO4− in groundwater and soils/caliche in arid and semi-arid environments (southwestern United States, southern Africa, United Arab Emirates, China, Antarctica, and Chile) and the relationship of ClO4− to the more well-studied atmospherically deposited anions NO3−and Cl− as a means to understand the prevalent processes that affect the accumulation of these species over various time scales. ClO4− is globally distributed in soil and groundwater in arid and semi-arid regions on Earth at concentrations ranging from 10−1to 106 μg/kg. Generally, the ClO4− concentration in these regions increases with aridity index, but also depends on the duration of arid conditions. In many arid and semi-arid areas, NO3− and ClO4− co-occur at molar ratios (NO3−/ClO4−) that vary between ∼104and 105. We hypothesize that atmospheric deposition ratios are largely preserved in hyper-arid areas that support little or no biological activity (e.g. plants or bacteria), but can be altered in areas with more active biological processes including N2 fixation, N mineralization, nitrification, denitrification, and microbial ClO4− reduction, as indicated in part by NO3− isotope data. In contrast, much larger ranges of Cl−/ClO4− and Cl−/NO3−ratios indicate Cl− varies independently from both ClO4− and NO3−. The general lack of correlation between Cl− and ClO4− or NO3− implies that Cl− is not a good indicator of co-deposition and should be used with care when interpreting oxyanion cycling in arid systems. The Atacama Desert appears to be unique compared to all other terrestrial locations having a

  17. EnviroAtlas - Ecosystem Service Market and Project Enabling Conditions, U.S., 2016, Forest Trends' Ecosystem Marketplace

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset contains polygons depicting conditions enabling market-based programs, referred to herein as markets, and projects addressing ecosystem...

  18. EnviroAtlas - Ecosystem Service Market and Project Locations, U.S., 2015, Forest Trends' Ecosystem Marketplace

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset contains points depicting the location of market-based programs, referred to herein as markets, and projects addressing ecosystem services...

  19. EnviroAtlas - Ecosystem Service Market and Project Areas, U.S., 2015, Forest Trends' Ecosystem Marketplace

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset contains polygons depicting the geographic areas of market-based programs, referred to herein as markets, and projects addressing ecosystem...

  20. Simulated changes in aridity from the last glacial maximum to 4xCO2

    Science.gov (United States)

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

    2017-11-01

    Aridity is generally defined as the ‘degree to which a climate lacks moisture to sustain life in terrestrial ecosystems’. Several recent studies using the ‘aridity index’ (the ratio of potential evaporation to precipitation), have concluded that aridity will increase with CO2 because of increasing temperature. However, the ‘aridity index’ is—counterintuitively—not a direct measure of aridity per se (when defined as above) and there is widespread evidence that contradicts the ‘warmer is more arid’ interpretation. We provide here an assessment of multi-model changes in a broad set of aridity metrics over a large range of atmospheric CO2 concentrations ranging from conditions at the last glacial maximum to 4xCO2, using an ensemble of simulations from state-of-the-art Earth system models. Most measures of aridity do not show increasing aridity on global scales under conditions of increasing atmospheric CO2 concentrations and related global warming, although we note some varying responses depending on the considered variables. The response is, furthermore, more nuanced at regional scales, but in the majority of regions aridity does not increase with CO2 in the majority of metrics. Our results emphasize that it is not the climate models that project overwhelming increases of aridity with increasing CO2, but rather a secondary, offline, impact model—the ‘aridity index’—that uses climate model output as input.

  1. Do Red Edge and Texture Attributes from High-Resolution Satellite Data Improve Wood Volume Estimation in a Semi-Arid Mountainous Region?

    DEFF Research Database (Denmark)

    Schumacher, Paul; Mislimshoeva, Bunafsha; Brenning, Alexander

    2016-01-01

    Remote sensing-based woody biomass quantification in sparsely-vegetated areas is often limited when using only common broadband vegetation indices as input data for correlation with ground-based measured biomass information. Red edge indices and texture attributes are often suggested as a means...... red edge and texture attributes, to estimate wood volume in semi-arid ecosystems characterized by scarce vegetation. LASSO (Least Absolute Shrinkage and Selection Operator) and random forest were used as predictive models relating in situ-measured aboveground standing wood volume to satellite data...

  2. Water- and plant-mediated responses of ecosystem carbon fluxes to warming and nitrogen addition on the Songnen grassland in northeast China.

    Directory of Open Access Journals (Sweden)

    Li Jiang

    Full Text Available BACKGROUND: Understanding how grasslands are affected by a long-term increase in temperature is crucial to predict the future impact of global climate change on terrestrial ecosystems. Additionally, it is not clear how the effects of global warming on grassland productivity are going to be altered by increased N deposition and N addition. METHODOLOGY/PRINCIPAL FINDINGS: In-situ canopy CO(2 exchange rates were measured in a meadow steppe subjected to 4-year warming and nitrogen addition treatments. Warming treatment reduced net ecosystem CO(2 exchange (NEE and increased ecosystem respiration (ER; but had no significant impacts on gross ecosystem productivity (GEP. N addition increased NEE, ER and GEP. However, there were no significant interactions between N addition and warming. The variation of NEE during the four experimental years was correlated with soil water content, particularly during early spring, suggesting that water availability is a primary driver of carbon fluxes in the studied semi-arid grassland. CONCLUSION/SIGNIFICANCE: Ecosystem carbon fluxes in grassland ecosystems are sensitive to warming and N addition. In the studied water-limited grassland, both warming and N addition influence ecosystem carbon fluxes by affecting water availability, which is the primary driver in many arid and semiarid ecosystems. It remains unknown to what extent the long-term N addition would affect the turn-over of soil organic matter and the C sink size of this grassland.

  3. 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.

  4. Response of carbon dioxide exchange to grazing intensity over typical steppes in a semi-arid area of Inner Mongolia

    Science.gov (United States)

    Wang, Lei; Liu, Huizhi; Bernhofer, Christian

    2017-05-01

    The eddy covariance technique was used to measure the CO2 flux over four differently grazed Leymus chinensis steppe ecosystems (ungrazed since 1979 (UG79), winter grazed (WG), continuously grazed (CG), and heavily grazed (HG) sites) during four growing seasons (May to September) from 2005 to 2008, to investigate the response of the net ecosystem exchange (NEE) over grassland ecosystems to meteorological factors and grazing intensity. At UG79, the optimal air temperature for the half-hourly NEE occurred between 17 and 20 °C, which was relatively low for semi-arid grasslands. The saturated NEE (NEEsat) and temperature sensitivity coefficient ( Q 10) of ecosystem respiration (RE) exhibited clear seasonal and interannual variations, which increased with canopy development and the soil water content (SWC, at 5 cm). The total NEE values for the growing seasons from 2005 to 2008 were -32.0, -41.5, -66.1, and -89.8 g C m-2, respectively. Both the amounts and distribution of precipitation during the growing season affected the NEE. The effects of grazing on the CO2 flux increased with the grazing intensity. During the peak growth stage, heavy grazing and winter grazing decreased NEEsat and gross primary production (45 % for HG and 34 % for WG) due to leaf area removal. Both RE and Q 10 were clearly reduced by heavy grazing. Heavy grazing changed the ecosystem from a CO2 sink into a CO2 source, and winter grazing reduced the total CO2 uptake by 79 %. In the early growing season, there was no difference in the NEE between CG and UG79. In addition to the grazing intensity, the effects of grazing on the CO2 flux also varied with the vegetation growth stages and SWC.

  5. Columbia River Estuary Ecosystem Classification Ecosystem Complex

    Science.gov (United States)

    Cannon, Charles M.; Ramirez, Mary F.; Heatwole, Danelle W.; Burke, Jennifer L.; Simenstad, Charles A.; O'Connor, Jim E.; Marcoe, Keith Marcoe

    2012-01-01

    Estuarine ecosystems are controlled by a variety of processes that operate at multiple spatial and temporal scales. Understanding the hierarchical nature of these processes will aid in prioritization of restoration efforts. This hierarchical Columbia River Estuary Ecosystem Classification (henceforth "Classification") of the Columbia River estuary is a spatial database of the tidally-influenced reaches of the lower Columbia River, the tidally affected parts of its tributaries, and the landforms that make up their floodplains for the 230 kilometers between the Pacific Ocean and Bonneville Dam. This work is a collaborative effort between University of Washington School of Aquatic and Fishery Sciences (henceforth "UW"), U.S. Geological Survey (henceforth "USGS"), and the Lower Columbia Estuary Partnership (henceforth "EP"). Consideration of geomorphologic processes will improve the understanding of controlling physical factors that drive ecosystem evolution along the tidal Columbia River. The Classification is organized around six hierarchical levels, progressing from the coarsest, regional scale to the finest, localized scale: (1) Ecosystem Province; (2) Ecoregion; (3) Hydrogeomorphic Reach; (4) Ecosystem Complex; (5) Geomorphic Catena; and (6) Primary Cover Class. For Levels 4 and 5, we mapped landforms within the Holocene floodplain primarily by visual interpretation of Light Detection and Ranging (LiDAR) topography supplemented with aerial photographs, Natural Resources Conservation Service (NRCS) soils data, and historical maps. Mapped landforms are classified as to their current geomorphic function, the inferred process regime that formed them, and anthropogenic modification. Channels were classified primarily by a set of depth-based rules and geometric relationships. Classification Level 5 floodplain landforms ("geomorphic catenae") were further classified based on multivariate analysis of land-cover within the mapped landform area and attributed as "sub

  6. Functional traits drive the contribution of solar radiation to leaf litter decomposition among multiple arid-zone species.

    Science.gov (United States)

    Pan, Xu; Song, Yao-Bin; Liu, Guo-Fang; Hu, Yu-Kun; Ye, Xue-Hua; Cornwell, William K; Prinzing, Andreas; Dong, Ming; Cornelissen, Johannes H C

    2015-08-18

    In arid zones, strong solar radiation has important consequences for ecosystem processes. To better understand carbon and nutrient dynamics, it is important to know the contribution of solar radiation to leaf litter decomposition of different arid-zone species. Here we investigated: (1) whether such contribution varies among plant species at given irradiance regime, (2) whether interspecific variation in such contribution correlates with interspecific variation in the decomposition rate under shade; and (3) whether this correlation can be explained by leaf traits. We conducted a factorial experiment to determine the effects of solar radiation and environmental moisture for the mass loss and the decomposition constant k-values of 13 species litters collected in Northern China. The contribution of solar radiation to leaf litter decomposition varied significantly among species. Solar radiation accelerated decomposition in particular in the species that already decompose quickly under shade. Functional traits, notably specific leaf area, might predict the interspecific variation in that contribution. Our results provide the first empirical evidence for how the effect of solar radiation on decomposition varies among multiple species. Thus, the effect of solar radiation on the carbon flux between biosphere and atmosphere may depend on the species composition of the vegetation.

  7. Effects of soil C:N:P stoichiometry on biomass allocation in the alpine and arid steppe systems.

    Science.gov (United States)

    Wang, Xiaodan; Ma, Xingxing; Yan, Yan

    2017-03-01

    Soil nutrients strongly influence biomass allocation. However, few studies have examined patterns induced by soil C:N:P stoichiometry in alpine and arid ecosystems. Samples were collected from 44 sites with similar elevation along the 220-km transect at spatial intervals of 5 km along the northern Tibetan Plateau. Aboveground biomass (AGB) levels were measured by cutting a sward in each plot. Belowground biomass (BGB) levels were collected from soil pits in a block of 1 m × 1 m in actual root depth. We observed significant decreases in AGB and BGB levels but increases in the BGB:AGB ratio with increases in latitude. Although soil is characterized by structural complexity and spatial heterogeneity, we observed remarkably consistent C:N:P ratios within the cryic aridisols. We observed significant nonlinear relationships between the soil N:P and BGB:AGB ratios. The critical N:P ratio in soils was measured at approximately 2.0, above which the probability of BGB:AGB response to nutrient availability is small. These findings serve as interesting contributions to the global data pool on arid plant stoichiometry, given the previously limited knowledge regarding high-altitude regions.

  8. Modeling Ocean Ecosystems: The PARADIGM Program

    Science.gov (United States)

    2006-03-01

    light limited in early occurs at a time when the ambient nutri- July. Eddies play an important role in determining the mean. Oceanio 5 raph’y I Vol. 19...hierarchal istics (initially, growth responses to light (Doney et al., 2004; DeLong and Karl, approach to modeling. The broad inter- and ambient ... gestions from anonymous reviewers. J. time and space scales depends, of course, data fusion systems (e.g., the direct Cullen was also supported by ONR, the

  9. Formation of Service Ecosystems

    DEFF Research Database (Denmark)

    Jonas, Julia M.; Sörhammar, David; Satzger, Gerhard

    Purpose: Researchers in several different academic disciplines (such as marketing, information systems, and organization) have focused on investigating service and business ecosystems (e.g. Lusch and Nambisan, 2015; Gawer and Cusumano, 2014; Kude et al. 2012). We reviewed 69 papers in service...... science, operations management, marketing, and organization journals. The majority of these papers focus on describing established service ecosystems,often on a more abstract “meso-level” (Akaka et al., 2015). Key notions are “…self-contained, self-adjusting system[s] of resource integrating actors...... connected by shared institutional arrangements and mutual value creation” (Vargo & Lusch, 2015) or “value co-creation configurations of people, technology, value propositions … and shared information” (Maglio &Spohrer, 2008). Little is known, though, of how service ecosystems emerge and become established...

  10. Remote Sensing of Mangrove Ecosystems: A Review

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    Stefan Dech

    2011-04-01

    Full Text Available Mangrove ecosystems dominate the coastal wetlands of tropical and subtropical regions throughout the world. They provide various ecological and economical ecosystem services contributing to coastal erosion protection, water filtration, provision of areas for fish and shrimp breeding, provision of building material and medicinal ingredients, and the attraction of tourists, amongst many other factors. At the same time, mangroves belong to the most threatened and vulnerable ecosystems worldwide and experienced a dramatic decline during the last half century. International programs, such as the Ramsar Convention on Wetlands or the Kyoto Protocol, underscore the importance of immediate protection measures and conservation activities to prevent the further loss of mangroves. In this context, remote sensing is the tool of choice to provide spatio-temporal information on mangrove ecosystem distribution, species differentiation, health status, and ongoing changes of mangrove populations. Such studies can be based on various sensors, ranging from aerial photography to high- and medium-resolution optical imagery and from hyperspectral data to active microwave (SAR data. Remote-sensing techniques have demonstrated a high potential to detect, identify, map, and monitor mangrove conditions and changes during the last two decades, which is reflected by the large number of scientific papers published on this topic. To our knowledge, a recent review paper on the remote sensing of mangroves does not exist, although mangrove ecosystems have become the focus of attention in the context of current climate change and discussions of the services provided by these ecosystems. Also, climate change-related remote-sensing studies in coastal zones have increased drastically in recent years. The aim of this review paper is to provide a comprehensive overview and sound summary of all of the work undertaken, addressing the variety of remotely sensed data applied for mangrove

  11. Organic amendments as restoration techniques in degraded arid and semiarid systems: A review

    Science.gov (United States)

    Hueso-González, Paloma; Muñoz-Rojas, Miriam

    2017-04-01

    There is an increasing concern at the global scale about interrelated environmental problems such as soil degradation, desertification, erosion, and climate change impacts (Hueso-Gonzalez et al., 2014). Indiscriminate use of agro-chemicals, excessive and deep tillage, excessive irrigation, among many others factors, have largely contributed to soil degradation, particularly in arid and semi-arid areas (Lal, 2008). Soil is an essential non-renewable resource with extremely slow formation and regeneration potential (Muñoz-Rojas et al., 2016a and c, Martínez-Murillo et al., 2016). The decline in organic matter content of many soils is becoming a major cause of soil degradation, particularly in dryland regions (Muñoz-Rojas et al., 2016b) where low soil fertility cannot maintain sustainable production in many cases (Hueso-González et al., 2015). The use of soil organic amendments is a common practice in agricultural management and land restoration that can help to improve physical and chemical soil properties, soil structure, temperature and humidity conditions, as well as nutrient contents which are essential for plant growth (Guerrero et al., 2001). Under degraded conditions, several studies have shown their benefits for improving soil physical, chemical and biological properties (Jordan et al., 2010 and 2011). However, there are many research gaps in the knowledge of the effects of climatic conditions on their application, as well as the adequate types of amendment and doses and decomposition rates, (Hueso-Gonzalez,2016). All these factors are crucial for the success in their application. Here, we review long-term experiments worldwide studying the benefits associated with the application of organic materials, particularly, in restoration of arid and semiarid ecosystems together with the possible threats and risks that can result from their use. We will specifically adress: (1) type of amended and benefits arising from their use, (2) application methods and more

  12. Revealing Invisible Water: Moisture Recycling as an Ecosystem Service.

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    Patrick W Keys

    Full Text Available An ecosystem service is a benefit derived by humanity that can be traced back to an ecological process. Although ecosystem services related to surface water have been thoroughly described, the relationship between atmospheric water and ecosystem services has been mostly neglected, and perhaps misunderstood. Recent advances in land-atmosphere modeling have revealed the importance of terrestrial ecosystems for moisture recycling. In this paper, we analyze the extent to which vegetation sustains the supply of atmospheric moisture and precipitation for downwind beneficiaries, globally. We simulate land-surface evaporation with a global hydrology model and track changes to moisture recycling using an atmospheric moisture budget model, and we define vegetation-regulated moisture recycling as the difference in moisture recycling between current vegetation and a hypothetical desert world. Our results show that nearly a fifth of annual average precipitation falling on land is from vegetation-regulated moisture recycling, but the global variability is large, with many places receiving nearly half their precipitation from this ecosystem service. The largest potential impacts for changes to this ecosystem service are land-use changes across temperate regions in North America and Russia. Likewise, in semi-arid regions reliant on rainfed agricultural production, land-use change that even modestly reduces evaporation and subsequent precipitation, could significantly affect human well-being. We also present a regional case study in the Mato Grosso region of Brazil, where we identify the specific moisture recycling ecosystem services associated with the vegetation in Mato Grosso. We find that Mato Grosso vegetation regulates some internal precipitation, with a diffuse region of benefit downwind, primarily to the south and east, including the La Plata River basin and the megacities of Sao Paulo and Rio de Janeiro. We synthesize our global and regional results

  13. Influence of Microclimate on Semi-Arid Montane Conifer Forest Sapflux Velocity in Complex Terrain

    Science.gov (United States)

    Thirouin, K. R.; Barnard, D. M.; Barnard, H. R.

    2016-12-01

    Microclimate variation in complex terrain is key to our understanding of large-scale climate change effects on montane ecosystems. Modern climate models forecast that semi-arid montane ecosystems in the western United States are to experience increases in temperature, number of extreme drought events, and decreases in annual snowpack, all of which will potentially influence ecosystem water, carbon, and energy balances. In this study, we developed response curves that describe the relationships between stem sapflux velocity, air temperature (Tair), incoming solar radiation (SWin), soil temperature (Tsoil), and soil moisture content (VWC) in sites of Pinus contorta and Pinus ponderosa distributed along an elevation and aspect gradient in the montane zone of the Central Rocky Mountains, Colorado, USA. Among sites we found sapflux velocity to be significantly correlated with all four environmental factors (p < 0.05), but most strongly with SWin and Tair. The response of sapflux velocity to SWin was logarithmic, whereas the response to Tair indicated a peak sapflux velocity at a site-specific temperature that declined with increasing Tair. Sapflux velocity also increased with increasing VWC, but decreased with increasing Tsoil. At south-facing sites, the initial increase in the logarithmic response curve for SWin leveled off at 150-250 W m-2, whereas for north-facing sites it leveled off at 50-125 W m-2. While the differences in the SWin response between aspects could be due to species physiological differences, the highest elevation south-facing P. contorta site behaved similarly to the south-facing P. ponderosa, suggesting that environmental drivers may dominate the response. In response to Tair, peak sapflux velocity occurred at 12-13 degrees C at all sites except the mid-slope north-facing P. contorta site, which also had the lowest Tsoil. The responses of stem sapflux velocity to climate drivers indicate that forest transpiration is regulated by microclimate

  14. Global Trends in Exposure to Light Pollution in Natural Terrestrial Ecosystems

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    Jonathan Bennie

    2015-03-01

    Full Text Available The rapid growth in electric light usage across the globe has led to increasing presence of artificial light in natural and semi-natural ecosystems at night. This occurs both due to direct illumination and skyglow - scattered light in the atmosphere. There is increasing concern about the effects of artificial light on biological processes, biodiversity and the functioning of ecosystems. We combine intercalibrated Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS images of stable night-time lights for the period 1992 to 2012 with a remotely sensed landcover product (GLC2000 to assess recent changes in exposure to artificial light at night in 43 global ecosystem types. We find that Mediterranean-climate ecosystems have experienced the greatest increases in exposure, followed by temperate ecosystems. Boreal, Arctic and montane systems experienced the lowest increases. In tropical and subtropical regions, the greatest increases are in mangroves and subtropical needleleaf and mixed forests, and in arid regions increases are mainly in forest and agricultural areas. The global ecosystems experiencing the greatest increase in exposure to artificial light are already localized and fragmented, and often of particular conservation importance due to high levels of diversity, endemism and rarity. Night time remote sensing can play a key role in identifying the extent to which natural ecosystems are exposed to light pollution.

  15. 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. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental

  16. Too Much or Too Little? Eco-hydrology in Arid and Semi-arid Regions

    Science.gov (United States)

    Toch, S. L.

    2009-04-01

    Around the world, disastrous effects of floods and droughts are painful evidence of our continuing struggle between human resource demands and the sustainability of our hydrologic ecosystems. Too much or too little rainfall is often deemed the culprit in these water crises, focusing on water "lacks and needs" instead of exploring the diverse mechanisms of the hydrologic functions and processes that sustain us. Applicable to regions around the world, this unified approach focuses on the connections between our human and ecological qualities, with user friendly concepts and how-to guides backed up by real life experiences. From the poorest parts of Africa to Urban France to the wealthiest state in the USA, examples from surface to groundwater to marine environments demonstrate how the links between vulnerable natural areas, and the basins that they support are integral to the availability, adequacy and accessibility of our drinking water. The interactions of watersheds within our diverse communities can link our resource practices with our human needs, serving as a basis for our ecological health and human well-being. Hydrologic ecosystems provide links to geographic and cultural information traversing physical and social boundaries. This international, community-based project demonstrates how our human resource demands can be managed within ecological constraints. An inter-disciplinary process is used that specifically explores the connections between ecological integrity and the preservation of potable supplies. A monitoring strategy is developed that assesses risk to human health from resource use practices, and explores the similarities and interactions between our human needs and those of the ecosystems in which we all must live together. This work is geared as a reference for groups, individuals and agencies concerned with land use and watershed management, a supplement for interdisciplinary high school through University curriculum, for professional

  17. Seasonal variation of carbon fluxes in a sparse savanna in semi arid Sudan

    Directory of Open Access Journals (Sweden)

    El-Tahir Bashir

    2008-12-01

    Full Text Available Abstract Background Large spatial, seasonal and annual variability of major drivers of the carbon cycle (precipitation, temperature, fire regime and nutrient availability are common in the Sahel region. This causes large variability in net ecosystem exchange and in vegetation productivity, the subsistence basis for a major part of the rural population in Sahel. This study compares the 2005 dry and wet season fluxes of CO2 for a grass land/sparse savanna site in semi arid Sudan and relates these fluxes to water availability and incoming photosynthetic photon flux density (PPFD. Data from this site could complement the current sparse observation network in Africa, a continent where climatic change could significantly impact the future and which constitute a weak link in our understanding of the global carbon cycle. Results The dry season (represented by Julian day 35–46, February 2005 was characterized by low soil moisture availability, low evapotranspiration and a high vapor pressure deficit. The mean daily NEE (net ecosystem exchange, Eq. 1 was -14.7 mmol d-1 for the 12 day period (negative numbers denote sinks, i.e. flux from the atmosphere to the biosphere. The water use efficiency (WUE was 1.6 mmol CO2 mol H2O-1 and the light use efficiency (LUE was 0.95 mmol CO2 mol PPFD-1. Photosynthesis is a weak, but linear function of PPFD. The wet season (represented by Julian day 266–273, September 2005 was, compared to the dry season, characterized by slightly higher soil moisture availability, higher evapotranspiration and a slightly lower vapor pressure deficit. The mean daily NEE was -152 mmol d-1 for the 8 day period. The WUE was lower, 0.97 mmol CO2 mol H2O-1 and the LUE was higher, 7.2 μmol CO2 mmol PPFD-1 during the wet season compared to the dry season. During the wet season photosynthesis increases with PPFD to about 1600 μmol m-2s-1 and then levels off. Conclusion Based on data collected during two short periods, the studied ecosystem

  18. Carbon Dioxide Fluxes and Their Environmental Controls in a Riparian Forest within the Hyper-Arid Region of Northwest China

    Directory of Open Access Journals (Sweden)

    Xiaohong Ma

    2017-10-01

    Full Text Available Hyper-arid regions are expected to undergo climatic change, but only a few research works have so far been conducted on the dynamics of carbon dioxide (CO2 fluxes and their consequent responses to various bioclimatic factors, which is mainly attributable to a limited set of flux observations. In this study, the CO2 fluxes exchanged between the forest and the atmosphere have been measured continuously by the eddy covariance approach from June 2013 to December 2016 in a riparian forest, which is a primary body of natural oases located within the lower reaches of inland rivers in China. The present results revealed that the climatic conditions characterized by relatively high mean air temperatures (Ta with fluctuating annual precipitation (P during the prescribed study periods were comparable to the historical mean value. The annual net ecosystem productivity (NEP ranged from approximately 278 g C m−2 year−1 to 427 g C m−2 year−1, with a mean value of 334 g C m−2 year−1. The mean annual ecosystem respiration (Re and the gross primary productivity (GPP were found to be 558 and 892 g C m−2 year−1, respectively. The results also ascertained that the high inter-annual variations in NEP were attributable to Re rather than to GPP, and this result was driven primarily by Ta and the groundwater depth under similar eco-physiological processes. In addition, the CO2 fluxes were also strongly correlated with the soil temperature and photosynthetically active radiation for the present study site. In conclusion, the desert riparian forest is a considerably significant carbon sink, particularly in the hyper-arid regions.

  19. 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

  20. Seasonal diet and prey preference of the African lion in a waterhole-driven semi-arid savanna.

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    Zeke Davidson

    Full Text Available Large carnivores inhabiting ecosystems with heterogeneously distributed environmental resources with strong seasonal variations frequently employ opportunistic foraging strategies, often typified by seasonal switches in diet. In semi-arid ecosystems, herbivore distribution is generally more homogeneous in the wet season, when surface water is abundant, than in the dry season when only permanent sources remain. Here, we investigate the seasonal contribution of the different herbivore species, prey preference and distribution of kills (i.e. feeding locations of African lions in Hwange National Park, Zimbabwe, a semi-arid African savanna structured by artificial waterholes. We used data from 245 kills and 74 faecal samples. Buffalo consistently emerged as the most frequently utilised prey in all seasons by both male (56% and female (33% lions, contributing the most to lion dietary biomass. Jacobs' index also revealed that buffalo was the most intensively selected species throughout the year. For female lions, kudu and to a lesser extent the group "medium Bovidae" are the most important secondary prey. This study revealed seasonal patterns in secondary prey consumption by female lions partly based on prey ecology with browsers, such as giraffe and kudu, mainly consumed in the early dry season, and grazers, such as zebra and suids, contributing more to female diet in the late dry season. Further, it revealed the opportunistic hunting behaviour of lions for prey as diverse as elephants and mice, with elephants taken mostly as juveniles at the end of the dry season during droughts. Jacobs' index finally revealed a very strong preference for kills within 2 km from a waterhole for all prey species, except small antelopes, in all seasons. This suggested that surface-water resources form passive traps and contribute to the structuring of lion foraging behaviour.

  1. Modeling of hydrological processes in arid agricultural regions

    Directory of Open Access Journals (Sweden)

    Jiang LI,Xiaomin MAO,Shaozhong KANG,David A. BARRY

    2015-12-01

    Full Text Available Understanding of hydrological processes, including consideration of interactions between vegetation growth and water transfer in the root zone, underpins efficient use of water resources in arid-zone agriculture. Water transfers take place in the soil-plant-atmosphere continuum, and include groundwater dynamics, unsaturated zone flow, evaporation/transpiration from vegetated/bare soil and surface water, agricultural canal/surface water flow and seepage, and well pumping. Models can be categorized into three classes: (1 regional distributed hydrological models with various land uses, (2 groundwater-soil-plant-atmosphere continuum models that neglect lateral water fluxes, and (3 coupled models with groundwater flow and unsaturated zone water dynamics. This review highlights, in addition, future research challenges in modeling arid-zone agricultural systems, e.g., to effectively assimilate data from remote sensing, and to fully reflect climate change effects at various model scales.

  2. How Sustainable are Engineered Rivers in Arid Lands?

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    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.

  3. Filling the interspace—restoring arid land mosses: source populations, organic matter, and overwintering govern success

    Science.gov (United States)

    Condon, Lea; Pyke, David A.

    2016-01-01

    Biological soil crusts contribute to ecosystem functions and occupy space that could be available to invasive annual grasses. Given disturbances in the semiarid shrub steppe communities, we embarked on a set of studies to investigate restoration potential of mosses in sagebrush steppe ecosystems. We examined establishment and growth of two moss species common to the Great Basin, USA: Bryum argenteum and Syntrichia ruralis from two environmental settings (warm dry vs. cool moist). Moss fragments were inoculated into a third warm dry setting, on bare soil in spring and fall, both with and without a jute net and with and without spring irrigation. Moss cover was monitored in spring seasons of three consecutive years. Both moss species increased in cover over the winter. When Bryum received spring irrigation that was out of sync with natural precipitation patterns, moss cover increased and then crashed, taking two seasons to recover. Syntrichia did not respond to the irrigation treatment. The addition of jute net increased moss cover under all conditions, except Syntrichia following fall inoculation, which required a second winter to increase in cover. The warm dry population of Bryum combined with jute achieved on average 60% cover compared to the cool moist population that achieved only 28% cover by the end of the study. Differences were less pronounced for Syntrichia where moss from the warm dry population with jute achieved on average 51% cover compared to the cool moist population that achieved 43% cover by the end of the study. Restoration of arid land mosses may quickly protect soils from erosion while occupying sites before invasive plants. We show that higher moss cover will be achieved quickly with the addition of organic matter and when moss fragments originate from sites with a climate that is similar to that of the restoration site.

  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. Governing ecosystem services

    NARCIS (Netherlands)

    Verburg, René; Selnes, Trond; Verweij, Pita

    2016-01-01

    The TEEB approach to the use of ecosystem services has found its way to policy as a means to biodiversity conservation and greening of the economy. In this paper we analysed the uptake of the TEEB approach at national and local levels by applying a framework that revolves around the problem,

  6. Ecosystem quality in LCIA

    DEFF Research Database (Denmark)

    Woods, John S.; Damiani, Mattia; Fantke, Peter

    2017-01-01

    -richness-related metrics, with efforts made towards improved inclusion of ecosystem complexity. Impact indicators—which result from a range of modeling approaches that differ, for example, according to spatial and temporal scale, taxonomic coverage, and whether the indicator produces a relative or absolute measure of loss...

  7. Shelf-sea ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, J J

    1980-01-01

    An analysis of the food chain dynamics of the Oregon, Alaskan, and New York shelves is made with respect to differences in physical forcing of these ecosystems. The world's shelves are 10% of the area of the ocean, yield 99% of the world's fish catch, and may be a major sink in the global CO/sub 2/ budget.

  8. Restoring Forested Wetland Ecosystems

    Science.gov (United States)

    John A. Stanturf; Emile S. Gardiner; Melvin L. Warren

    2003-01-01

    Forests as natural systems are intrinsically linked to the sustainability of fresh-water systems. Efforts worldwide to restore forest ecosystems seek to counteract centuries of forest conversion to agriculture and other uses. Afforestation, the practice of regenerating forests on land deforested for agriculture or other uses, is occurring at an intense pace in the...

  9. nent of marine ecosystems

    African Journals Online (AJOL)

    spamer

    trophic web of marine ecosystems (Clarke 1980,. 1996, Rodhouse et al. 1987, 1992, Lipinski et al. 1992, Rodhouse and Nigmatullin 1996, Guerra et al. 1993). .... deep in the submucosa and were encapsulated in an amorphous eosinophilic substance. The anterior ex- tremities of nematodes and the vacated hyaline caps.

  10. Partitioning ecosystems for sustainability.

    Science.gov (United States)

    Murray, Martyn G

    2016-03-01

    Decline in the abundance of renewable natural resources (RNRs) coupled with increasing demands of an expanding human population will greatly intensify competition for Earth's natural resources during this century, yet curiously, analytical approaches to the management of productive ecosystems (ecological theory of wildlife harvesting, tragedy of the commons, green economics, and bioeconomics) give only peripheral attention to the driving influence of competition on resource exploitation. Here, I apply resource competition theory (RCT) to the exploitation of RNRs and derive four general policies in support of their sustainable and equitable use: (1) regulate resource extraction technology to avoid damage to the resource base; (2) increase efficiency of resource use and reduce waste at every step in the resource supply chain and distribution network; (3) partition ecosystems with the harvesting niche as the basic organizing principle for sustainable management of natural resources by multiple users; and (4) increase negative feedback between consumer and resource to bring about long-term sustainable use. A simple policy framework demonstrates how RCT integrates with other elements of sustainability science to better manage productive ecosystems. Several problem areas of RNR management are discussed in the light of RCT, including tragedy of the commons, overharvesting, resource collapse, bycatch, single species quotas, and simplification of ecosystems.

  11. Loess is the accumulation of dust, not evidence for aridity

    Science.gov (United States)

    Zech, Roland

    2013-04-01

    Loess-paleosol sequences (LPS) are valuable terrestrial archives for Quaternary climate and environmental changes. The famous sections on the Chinese Loess Plateau, for example, document the alternation of warm and humid interglacials (paleosols) and cold and more arid glacials (loess). This, at least partly, reflects the weakening of the monsoonal circulation during glacials and has led to the notion that loess in general documents more arid conditions. Paleosols, on the other hand, are often interpreted to document more humid conditions. We studied the LPS Crvenka in the Carpathian Basin, southeast Europe, which spans the full last glacial cycle, and obtained results that do not fit the above concept: (i) The analysis of plant-derived long-chain n-alkanes indicates the presence of deciduous trees and shrubs during glacials, i.e. sufficient precipitation for tree growth, whereas tree-less grass steppes seem to have prevailed during the Eemian, the last interglacial. (ii) Compound-specific deuterium analyses on the alkanes show only little changes on glacial-interglacial timescale. When compared with the isotopic enrichment of the Mediterranean Sea during the last glacial, this likely documents a combination of increased rainfall, reduced evapo-transpiration and reduced temperatures. (iii) Novel lipid biomarkers derived from soil bacteria (GDGTs, glycerol dialkyl glycerol tetraethers) also indicate humid glacials (BIT index close to 1) and more arid interglacials (BITaridization in the Mediterranean area in response to man-made global warming. More importantly, they remind us of an important fact: Loess is the accumulation of dust, but not (necessarily) evidence for aridity. Pedogenesis may simply not have been able to keep pace with high glacial dust accumulation rates related to intense glacial, periglacial and fluvial activity. Proxies independent of accumulation rates should be further developed and applied in LPS.

  12. Detection of Dirofilaria immitis in mid-western arid Argentina.

    Science.gov (United States)

    Cuervo, Pablo F; Mera Y Sierra, Roberto; Waisman, Viviana; Gerbeno, Leticia; Sidoti, Laura; Albonico, Francesca; Mariconti, Mara; Mortarino, Michele; Pepe, Paola; Cringoli, Giuseppe; Genchi, Claudio; Rinaldi, Laura

    2013-12-01

    Dirofilariosis, caused by Dirofilaria immitis and D. repens, is (re-) emerging worldwide. Dogs are the main reservoirs, while human infection has recently become an important focus of interest and attention. In Argentina, canine D. immitis infection has been described in eastern and northern subtropical and temperate humid regions, but never reported in mid-western arid regions so far. In this research note we report for the first time the occurrence of autochthonous human and canine D. immitis infection in the region.

  13. 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. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  14. Seasonal variation in water uptake patterns of three plant species based on stable isotopes in the semi-arid Loess Plateau.

    Science.gov (United States)

    Wang, Jian; Fu, Bojie; Lu, Nan; Zhang, Li

    2017-12-31

    Water is a limiting factor and significant driving force for ecosystem processes in arid and semi-arid areas. Knowledge of plant water uptake pattern is indispensable for understanding soil-plant interactions and species coexistence. The 'Grain for Green' project that started in 1999 in the Loess Plateau of China has led to large scale vegetation change. However, little is known about the water uptake patterns of the main plant species that inhabit in this region. In this study, the seasonal variations in water uptake patterns of three representative plant species, Stipa bungeana, Artemisia gmelinii and Vitex negundo, that are widely distributed in the semi-arid area of the Loess Plateau, were identified by using dual stable isotopes of δ2H and δ18O in plant and soil water coupled with a Bayesian mixing model MixSIAR. The soil water at the 0-120cm depth contributed 79.54±6.05% and 79.94±8.81% of the total water uptake of S. bungeana and A. gmelinii, respectively, in the growing season. The 0-40cm soil contributed the most water in July (74.20±15.20%), and the largest proportion of water (33.10±15.20%) was derived from 120-300cm soils in August for A. gmelinii. However, V. negundo obtained water predominantly from surface soil horizons (0-40cm) and then switched to deep soil layers (120-300cm) as the season progressed. This suggested that V. negundo has a greater degree of ecological plasticity as it could explore water sources from deeper soils as the water stress increased. This capacity can mainly be attributed to its functionally dimorphic root system. V. negundo may have a competitive advantage when encountering short-term drought. The ecological plasticity of plant water use needs to be considered in plant species selection and ecological management and restoration of the arid and semi-arid ecosystems in the Loess Plateau. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Mechanisms Controlling Variability of Lake Salinity in Dune Environments in a Semi-arid Climate: The Nebraska Sand Hills (Invited)

    Science.gov (United States)

    Zlotnik, V. A.; Ong, J. T.; Swinehart, J. B.; Fritz, S. C.; Lenters, J. D.; Schmieder, J. U.; Lane, J. W.; Halihan, T.

    2010-12-01

    Shallow endorheic saline lakes are common in semi-arid environments in North America, Africa, Asia, and Australia. These lakes receive minimal surface runoff and are supported by groundwater seepage. A combination of hydrologic and geologic factors (regional groundwater flow, evaporation, precipitation, lake size, groundwater recharge, and geologic setting) may preclude seepage out of these lakes, even in the presence of ambient regional flow. Solutes from groundwater are captured by these lakes and become enriched over time by evaporation. The importance of understanding lake dynamics in these arid and semi-arid systems is increasing with societal concerns, including water availability and quality, the use of aquatic ecosystems by waterfowl and other biota, and dangers of dust emissions associated with lake desiccation. We consider the salinity of shallow lakes as a useful indicator of hydroclimatic factors operating at centennial and millennial scales. The Nebraska Sand Hills cover 58 000 km2 of the central Great Plains and are the largest dunefield in the Western Hemisphere. The grass-stabilized dunes attain heights up to 130 m and have been modified by soil development and erosion. In an area lakes with surface areas >4 ha and depths lake evaporation exceeds precipitation by 600 mm, according to some estimates. The salinity of natural lakes in the Nebraska Sand Hills ranges from fresh (~0.3 g L-1) to hypersaline (>100 g L-1), with pH values as high as ~10. We assess the mechanisms that control lake salinity in a group of lakes with different subsurface flow regimes. Our methods combine aquifer coring, electromagnetic and electrical resistivity tomography geophysics, hydraulic testing, lakebed dating using 14C and optically stimulated luminescence, energy and water balance analysis, and salt crust and dust collection. Our theory and results show that terrain and water-table topography, lithology, and climate control the lake-aquifer solute exchanges. This study

  16. Flood monitoring in a semi-arid environment using spatially high resolution radar and optical data.

    Science.gov (United States)

    Seiler, Ralf; Schmidt, Jana; Diallo, Ousmane; Csaplovics, Elmar

    2009-05-01

    The geographic term "Niger Inland Delta" stands for a vast plain of approximately 40,000 km(2), which is situated in the western Sahel (Republic of Mali). The Inland Delta is affected by yearly inundation through the variable water levels of the Niger-Bani river system. Due to a good availability of (surface) water, the ecosystem at the Niger Inland Delta serves as resting place stop-over for many migrating birds and other wildlife species as well as economic base for farmers and pastoral people. To foster the sustainable usage of its natural resources and to protect this natural heritage, the entire Niger Inland Delta became RAMSAR site in 2004. This paper aims to test to which extent texture analysis can improve the quality of flood monitoring in a semi-arid environment using spatially high resolution ASAR imaging mode data. We found the Gray Level Dependence Method (GLDM) was most suitable proceeding for our data. Several statistical parameters were calculated via co-occurrence matrices and were used to classify the images in different gradation of soil moisture classes. In a second step we used additional information from spatially high resolution optical data (ASTER) to improve the separability of open water areas from moisture/vegetated areas.

  17. The Impact of Hydration and Temperature on Bacterial Diversity in Arid Soil Mesocosms.

    Science.gov (United States)

    Št'ovíček, Adam; Azatyan, Ani; Soares, M Ines M; Gillor, Osnat

    2017-01-01

    Hot desert ecosystems experience rare and unpredictable rainfall events that resuscitate the arid flora and fauna. However, the effect of this sudden abundance of water on soil microbial communities is still under debate. We modeled varying rainfall amounts and temperatures in desert soil mesocosms and monitored the microbial community response over a period of 21 days. We studied two different wetting events, simulating heavy (50 mm) and light (10 mm) rain, as well as three different temperature regimes: constant 25° or 36°C, or a temperature diurnal cycle alternating between 36 and 10 °C. Amplicon sequencing of the bacterial ribosomal RNA revealed that rain intensity affects the soil bacterial community, but the effects are mitigated by temperature. The combination of water-pulse intensity with lower temperature had the greatest effect on the bacterial community. These experiments demonstrated that the soil microbial response to rain events is dependent not only on the intensity of the water pulse but also on the ambient temperature, thus emphasizing the complexity of bacterial responses to highly unpredictable environments.

  18. The First Law of Thermodynamics for Ecosystems. Physical Processes in Terrestrial and Aquatic Ecosystems, Thermodynamics.

    Science.gov (United States)

    Stevenson, R. D.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module and a comparison module are concerned with elementary concepts of thermodynamics as…

  19. Palaeoclimate and human occupation in southeastern arid Australia

    Science.gov (United States)

    Hughes, Philip J.; Sullivan, Marjorie E.; Hiscock, Peter

    2017-05-01

    This review focuses on the relationships between palaeoenvironmental change and prehistoric occupation in the driest part of the Australian arid zone. Palaeoclimatic evidence from the last ∼60 ka identified fluctuating periods of wet and dry conditions during the late Pleistocene and Holocene. For most of this period conditions were arid, including during the Holocene, and maximum aridity occurred at the LGM which peaked at ∼21 ka. Maximum wetness occurred before ∼45 ka, at ∼33-31 ka and episodically during the deglaciation between ∼18 and 11 ka. The pre-LGM archaeological record is extremely sparse but records from the LGM through to the mid Holocene show people occupied the dunefields and stony plains during prolonged wet periods in the deglaciation and largely abandoned them during drier phases, retreating to better-watered refuges. Human occupation in dunefields from the LGM through to the mid Holocene can be used as a proxy for past climates. From the late Holocene changes in settlement patterns were made possible by the social, economic and technological adaptations which allowed people to occupy what became an increasingly harsh environment. These reconstructions were facilitated by discoveries in the Roxby dunefield of buried stratified layers of stone artefacts in dune sands, dated by single-grain luminescence analyses. These discoveries indicate the possibility that hitherto unreported cultural sequences, potentially dating back to >50 ka, may be present in many Australian dunefields.

  20. 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.