The infrared emissivities of soil and Artemisia tridentata and subsequent temperature corrections in a shrub-steppe ecosystem

International Nuclear Information System (INIS)

Hipps, L.E.

1989-01-01

The determination of plant and soil temperatures using remote sensing technology is examined in a shrub-steppe ecosystem. The emissivities of Artemisia tridentata L. shrubs and the soil surface were examined in such an ecosystem. The emissivity of A. tridentata plants was calculated to be 0.97, which is in the range of reported values for other green plants. The soil emissivity was 0.93. Temperature readings from an infrared thermometer (IRT) must be corrected for the emissivity value of the target and the reflected sky radiation. Although these two factors produce errors which are opposite in sign, they will not offset one another. An analysis is presented which quantifies the temperature error resulting from ignoring the corrections. The error is negligible only for emissivity values greater than 0.98. The error is proportional to temperature, and increases rapidly with decreases in emissivity. The true emissivities must be determined, and the above corrections must be calculated in order to obtain accurate temperatures in an ecosystem from remote sensing methods. (author)

The infrared emissivities of soil and Artemisia tridentata and subsequent temperature corrections in a shrub-steppe ecosystem

International Nuclear Information System (INIS)

Hipps, L.E.

1989-01-01

The determination of plant and soil temperatures using remote sensing technology is examined in a shrub-steppe ecosystem. The emissivities of Artemisia tridentata L. shrubs and the soil surface were examined in such an ecosystem. The emissivity of A. tridentata plants was calculated to be 0.97, which is in the range of reported values for other green plants. The soil emissivity was 0.93. Temperature readings from an infrared thermometer (IRT) must be corrected for the emissivity value of the target and the reflected sky radiation. Although these two factors produce errors which are opposite in sign, they will not offset one another. An analysis is presented which quantifies the temperature error resulting from ignoring the corrections. The error is negligible only for emissivity values greater than 0.98. The error is proportional to temperature, and increases rapidly with decreases in emissivity. The true emissivities must be determined, and the above corrections must be calculated in order to obtain accurate temperatures in an ecosystem from remote sensing methods

Simulating the Dependence of Sagebrush Steppe Vegetation on Redistributed Snow in a Semi-Arid Watershed.

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Soderquist, B.; Kavanagh, K.; Link, T. E.; Strand, E. K.; Seyfried, M. S.

2014-12-01

In mountainous regions across the western USA, the composition of aspen (Populus tremuloides) and sagebrush steppe plant communities is often closely related to heterogeneous soil moisture subsidies resulting from redistributed snow. With decades of climate and precipitation data across elevational and precipitation gradients, the Reynolds Creek Experimental Watershed (RCEW) and critical zone observatory (CZO) in southwest Idaho provides a unique opportunity to study the relationship between vegetation types and redistributed snow. Within the RCEW, the total amount of precipitation has remained unchanged over the past 50 years, however the percentage of the precipitation falling as snow has declined by approximately 4% per decade at mid-elevation sites. As shifts in precipitation phase continue, future trends in vegetation composition and net primary productivity (NPP) of different plant functional types remains a critical question. We hypothesize that redistribution of snow may supplement drought sensitive species like aspen more so than drought tolerant species like mountain big sagebrush (Artemisia tridentata spp. vaseyana). To assess the importance of snowdrift subsidies on sagebrush steppe vegetation, NPP of aspen, shrub, and grass species was simulated at three sites using the biogeochemical process model BIOME-BGC. Each site is located directly downslope from snowdrifts providing soil moisture inputs to aspen stands and neighboring vegetation. Drifts vary in size with the largest containing up to four times the snow water equivalent (SWE) of a uniform precipitation layer. Precipitation inputs used by BIOME-BGC were modified to represent the redistribution of snow and simulations were run using daily climate data from 1985-2013. Simulated NPP of annual grasses at each site was not responsive to subsidies from drifting snow. However, at the driest site, aspen and shrub annual NPP was increased by as much as 44 and 30%, respectively, with the redistribution of

The value of small habitat islands for the conservation of genetic variability in a steppe grass species

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Wódkiewicz, Maciej; Dembicz, Iwona; Moysiyenko, Ivan I.

2016-10-01

The habitat loss and fragmentation due to agricultural land-conversion affected the steppe throughout its range. In Ukraine, 95% of steppe was destroyed in the last two centuries. Remaining populations are confined to few refuges, like nature reserves, loess ravines, and kurgans (small burial mounds), the latter being often subject to destruction by archeological excavations. Stipa capillata L. is a typical grass species of Eurasian steppes and extrazonal dry grasslands, that was previously used as a model species in studies on steppe ecology. The aim of our research was to assess genetic diversity of S. capillata populations within different types of steppe refuges (loess ravines, biosphere reserve, kurgan) and to evaluate the value of the latter group for the preservation of genetic diversity in the study species. We assessed genetic diversity of 266 individuals from 15 populations (nine from kurgans, three from loess ravines and three from Askania-Nova Biosphere Reserve) with eight Universal Rice Primers (URPs). Studied populations showed high intra-population variability (I: 0.262-0.419, PPB: 52.08-82.64%). Populations from kurgans showed higher genetic differentiation (ΦST = 0.247) than those from loess ravines (ΦST = 0.120) and the biosphere reserve (ΦST = 0.142). Although the diversity metrics were to a small extent lower for populations from kurgans than from larger refugia we conclude that all studied populations of the species still preserve high genetic variability and are valuable for protection. To what extent this pattern holds true under continuous fragmentation in the future must be carefully monitored.

Using Unmanned Aerial Vehicles to Assess Vegetative Cover in Sagebrush Steppe Ecosytstems

Energy Technology Data Exchange (ETDEWEB)

Robert P. Breckenridge

2005-09-01

The Idaho National Laboratory (INL), in conjunction with the University of Idaho, is evaluating novel approaches for using unmanned aerial vehicles (UAVs) as a quicker and safer method for monitoring biotic resources. Evaluating vegetative cover is an important factor in understanding the sustainability of many ecosystems. In assessing vegetative cover, methods that improve accuracy and cost efficiency could revolutionize how biotic resources are monitored on western federal lands. Sagebrush steppe ecosystems provide important habitat for a variety of species, some of which are important indicator species (e.g., sage grouse). Improved methods are needed to support monitoring these habitats because there are not enough resource specialists or funds available for comprehensive ground evaluation of these ecosystems. In this project, two types of UAV platforms (fixed wing and helicopter) were used to collect still-frame imagery to assess cover in sagebrush steppe ecosystems. This paper discusses the process for collecting and analyzing imagery from the UAVs to (1) estimate total percent cover, (2) estimate percent cover for six different types of vegetation, and (3) locate sage grouse based on representative decoys. The field plots were located on the INL site west of Idaho Falls, Idaho, in areas with varying amounts and types of vegetative cover. A software program called SamplePoint developed by the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS) was used to evaluate the imagery for percent cover for the six vegetation types (bare ground, litter, shrubs, dead shrubs, grasses, and forbs). Results were compared against standard field measurements to assess accuracy.

Shrub-Steppe Seasons A Natural History of the Mid-Columbia Basin

Energy Technology Data Exchange (ETDEWEB)

LE Rogers

1995-08-01

This book collects and updates a series of articles about the natural history of the Mid-Columbia region. The articles first appeared as a monthly column titled ''Natural History'' in the Tri-City Herald, beginning in May 1991. My approach has been to condense the best of what is known about the ecology of the region to a manageable length with little in the way of technical language and terms. Admittedly, there is a bias toward those topics and species on which I have either been personally involved or observed as part of the ecology research programs conducted on the Fitzner/Eberhardt Arid Lands Ecology (ALE) Reserve. The ALE Reserve is situated on the northeast-facing flank of the Rattlesnake Hills. Rattlesnake Mountain with a crest of over 3,600 feet is visible throughout much of the Mid-Columbia. Shrub-steppe grasslands once covered a large part of the western United States but most have been converted to other uses. The ALE site is the only remaining sizeable acreage (120 square miles) that is in near pristine condition and provides the only clear indication as to what the early trappers, traders, pioneers, and tribal members may have encountered in their day-to-day activities. In this respect, ALE provides a visible touchstone linking the past with the present for all of us.

Seed distribution of four co-occurring grasses around Artemisia halodendron shrubs in a sandy habitat

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Li, Feng-Rui; Zhao, Wen-Zhi; Kang, Ling-Fen; Liu, Ji-Liang; Huang, Zhi-Gang; Wang, Qi

2009-05-01

In a natural population of the perennial semi-shrub Artemisia halodendron in a shifting sandy habitat in the Horqin Desert of eastern Inner Mongolia, six isolated adult A. halodendron individuals of similar canopy size were chosen as target plants. The density of seeds in the top 5 cm soil depth around shrubs was measured using transects aligned to the four main wind directions and at different distances from the shrub base on both the windward and leeward sides. The effects of shrub presence on seed distribution of four co-occurring grasses were examined by linking seed distribution to seed traits. Of the four species, Setaris viridis and Eragrostis pilosa had small but similar seed mass, while Chloris virgata and Aristida adscensionis had large but similar seed mass. The species were grouped into two cohorts: small-seeded vs. large-seeded cohorts, and shrub presence effects on seed distribution of both cohorts were examined. We found marked difference in the seed distribution pattern among species, especially between the small-seeded and large-seeded cohorts. The small-seeded cohort had significantly higher seed accumulation on the windward than the leeward sides in the most and least prevailing wind directions and much higher seed accumulation on the leeward than the windward sides in the second and third most prevailing wind directions, while opposite patterns occurred in the large-seeded cohort. Four species also showed marked variation in the seed distribution pattern among transects and between windward and leeward sides of each transect. This study provided further evidence that shrubs embedded in a matrix of herbaceous plants is a key cause of spatial heterogeneity in seed availability of herbaceous species. However, seed distribution responses to the presence of shrubs will vary with species as well as with wind direction, sampling position (windward vs. leeward sides of the shrub) and distance from the shrub.

Usefulness of pioneer vegetation for the phytomanagement of metal(loid)s enriched tailings: grasses vs. shrubs vs. trees.

Science.gov (United States)

Parraga-Aguado, Isabel; Querejeta, Jose-Ignacio; González-Alcaraz, María-Nazaret; Jiménez-Cárceles, Francisco J; Conesa, Héctor M

2014-01-15

The goal of this work was to assess the selection of the most suitable combination of plant species for the phytomanagement of mine tailings, by comparing among different plant life-forms (grasses, shrubs and trees). A comparison on induced rhizosphere changes generated by four plant species (the grass Piptatherum miliaceum, the shrub Helichrysum decumbens, and the trees, Pinus halepensis and Tetraclinis articulata) and high density vegetation patches (fertility islands) at a mine tailing located at Southeast Spain and the description of their physiological status employing stable isotopes analyses were carried out. The edaphic niches for plant growth were determined by salinity, organic matter and total soil nitrogen while metal(loid)s concentrations played a minor role. Induced changes in plant rhizospheres had a significant impact in soil microbiology. While grasses and shrubs may play an important role in primary ecological succession, trees seem to be the key to the development of fertility islands. The low δ(15)N values (-8.00‰) in P. halepensis needles may reflect higher ectomycorrhizal dependence. Large differences in leaf δ(18)O among the plant species indicated contrasting and complementary water acquisition strategies. Leaf δ(13)C values (-27.6‰) suggested that T. articulata had higher water use efficiency than the rest of species (-29.9‰). The implement of a diverse set of plant species with contrasting life forms for revegetating tailings may result in a more efficient employment of water resources and a higher biodiversity not only in relation to flora but soil microbiology too. Copyright © 2013 Elsevier Ltd. All rights reserved.

Grasses as invasive plants in South Africa revisited: Patterns, pathways and management

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Vernon Visser

2017-03-01

Full Text Available Background: In many countries around the world, the most damaging invasive plant species are grasses. However, the status of grass invasions in South Africa has not been documented recently. Objectives: To update Sue Milton’s 2004 review of grasses as invasive alien plants in South Africa, provide the first detailed species level inventory of alien grasses in South Africa and assess the invasion dynamics and management of the group. Method: We compiled the most comprehensive inventory of alien grasses in South Africa to date using recorded occurrences of alien grasses in the country from various literature and database sources. Using historical literature, we reviewed past efforts to introduce alien grasses into South Africa. We sourced information on the origins, uses, distributions and minimum residence times to investigate pathways and patterns of spatial extent. We identified alien grasses in South Africa that are having environmental and economic impacts and determined whether management options have been identified, and legislation created, for these species. Results: There are at least 256 alien grass species in the country, 37 of which have become invasive. Alien grass species richness increased most dramatically from the late 1800s to about 1940. Alien grass species that are not naturalised or invasive have much shorter residence times than those that have naturalised or become invasive. Most grasses were probably introduced for forage purposes, and a large number of alien grass species were trialled at pasture research stations. A large number of alien grass species in South Africa are of Eurasian origin, although more recent introductions include species from elsewhere in Africa and from Australasia. Alien grasses are most prevalent in the south-west of the country, and the Fynbos Biome has the most alien grasses and the most widespread species. We identified 11 species that have recorded environmental and economic impacts in the

High-latitude steppe vegetation and the mineral nutrition of Pleistocene herbivores

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Davydov, S. P.; Davydova, A.; Makarevich, R.; Loranty, M. M.; Boeskorov, G.

2014-12-01

High-latitude steppes were widespread and zonal in the Late Pleistocene and formed a landscape basis for the Mammoth Biome. Now the patches of these steppes survived on steep slopes under southern aspects. These steppes serve as unique information sources about the Late Pleistocene "Mammoth" steppe. Numerous data obtained by palynological, carpological, and DNA analysis of plant remains from feces and stomach contents of Pleistocene herbivore mummies, as well as from buried soils and enclosing deposits show that they are similar to modern steppe plant assemblage in taxa composition. Plant's nutrient concentrations are of fundamental importance across Pleistocene grass-rich ecosystems because of their role in the support of large herbivores. The average weight of an adult mammoth skeleton (about 0.5 tons) and of a woolly rhinoceros (about 0.2 tons) clearly suggests this. Detailed studies on fossil bone remains showed mineral deficiency in large Pleistocene herbivores. A three-year study of ash and mineral contents of two types of relict steppe vegetation at the Kolyma Lowland, Arctic Siberia has been carried out. Nowadays refugia of similar vegetation are located not far (1 - 15km) from the Yedoma permafrost outcrops were abundant fossil remains are found. Dominant species of the steppe vegetation were sampled. Preliminary studies indicate that the ash-content varied 1.5-2 times in speceies of steppe herbs. The Ca, P, Mg, K element contents was higher for most steppe species than in the local herbaceous vegetation, especially in Ca and P. One of the most important elements of the mineral nutrition, the phosphorus, was always found in higher concentrations in the steppe vegetation than in plants of recently dominant landscapes of the study area. It should be noted that the mineral nutrient content of the modern steppe vegetation of Siberian Arctic is comparable to that of the recent zonal steppe of Transbaikal Region. This study supports the hypothesis that

Phenotypic sex ratios of Atriplex canescens shrubs in relation to cattle browsing

Science.gov (United States)

Andres F. Cibils; David M. Swift; Richard H. Hart

2001-01-01

Previous studies conducted at our research site on the shortgrass steppe in Colorado showed that phenotypic sex ratios of tetraploid fourwing saltbush (Atriplex canescens Pursh [Nutt]) shrubs were less female biased in grazed pastures than in adjacent exclosures. The potential effects of cattle browsing on shrub sex ratios were studied both in the field and in a...

A higher-level classification of the Pannonian and western Pontic steppe grasslands (Central and Eastern Europe).

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Willner, Wolfgang; Kuzemko, Anna; Dengler, Jürgen; Chytrý, Milan; Bauer, Norbert; Becker, Thomas; Biţă-Nicolae, Claudia; Botta-Dukát, Zoltán; Čarni, Andraž; Csiky, János; Igić, Ruzica; Kącki, Zygmunt; Korotchenko, Iryna; Kropf, Matthias; Krstivojević-Ćuk, Mirjana; Krstonošić, Daniel; Rédei, Tamás; Ruprecht, Eszter; Schratt-Ehrendorfer, Luise; Semenishchenkov, Yuri; Stančić, Zvjezdana; Vashenyak, Yulia; Vynokurov, Denys; Janišová, Monika

2017-01-01

What are the main floristic patterns in the Pannonian and western Pontic steppe grasslands? What are the diagnostic species of the major subdivisions of the class Festuco-Brometea (temperate Euro-Siberian dry and semi-dry grasslands)? Carpathian Basin (E Austria, SE Czech Republic, Slovakia, Hungary, Romania, Slovenia, N Croatia and N Serbia), Ukraine, S Poland and the Bryansk region of W Russia. We applied a geographically stratified resampling to a large set of relevés containing at least one indicator species of steppe grasslands. The resulting data set of 17 993 relevés was classified using the TWINSPAN algorithm. We identified groups of clusters that corresponded to the class Festuco-Brometea . After excluding relevés not belonging to our target class, we applied a consensus of three fidelity measures, also taking into account external knowledge, to establish the diagnostic species of the orders of the class. The original TWINSPAN divisions were revised on the basis of these diagnostic species. The TWINSPAN classification revealed soil moisture as the most important environmental factor. Eight out of 16 TWINSPAN groups corresponded to Festuco-Brometea . A total of 80, 32 and 58 species were accepted as diagnostic for the orders Brometalia erecti , Festucetalia valesiacae and Stipo-Festucetalia pallentis , respectively. In the further subdivision of the orders, soil conditions, geographic distribution and altitude could be identified as factors driving the major floristic patterns. We propose the following classification of the Festuco-Brometea in our study area: (1) Brometalia erecti (semi-dry grasslands) with Scabioso ochroleucae-Poion angustifoliae (steppe meadows of the forest zone of E Europe) and Cirsio-Brachypodion pinnati (meadow steppes on deep soils in the forest-steppe zone of E Central and E Europe); (2) Festucetalia valesiacae (grass steppes) with Festucion valesiacae (grass steppes on less developed soils in the forest-steppe zone of E Central

High precipitation and seeded species competition reduce seeded shrub establishment during dryland restoration.

Science.gov (United States)

Rinella, Matthew J; Hammond, Darcy H; Bryant, Ana-Elisa M; Kozar, Brian J

2015-06-01

Drylands comprise 40% of Earth's land mass and are critical to food security, carbon sequestration, and threatened and endangered wildlife. Exotic weed invasions, overgrazing, energy extraction, and other factors have degraded many drylands, and this has placed an increased emphasis on dryland restoration. The increased restoration focus has generated a wealth of experience, innovations and empirical data, yet the goal of restoring diverse, native, dryland plant assemblages composed of grasses, forbs, and shrubs has generally proven beyond reach. Of particular concern are shrubs, which often fail to establish or establish at trivially low densities. We used data from two Great Plains, USA coal mines to explore factors regulating shrub establishment. Our predictor data related to weather and restoration (e.g., seed rates, rock cover) variables, and our response data described shrub abundances on fields of the mines. We found that seeded non-shrubs, especially grasses, formed an important competitive barrier to shrub establishment: With every one standard deviation increase in non-shrub seed rate, the probability shrubs were present decreased ~0.1 and shrub cover decreased ~35%. Since new fields were seeded almost every year for > 20 years, the data also provided a unique opportunity to explore effects of stochastic drivers (i.e., precipitation, year effects). With every one standard deviation increase in precipitation the first growing season following seeding, the probability shrubs were present decreased ~0.07 and shrub cover decreased ~47%. High precipitation appeared to harm shrubs by increasing grass growth/competition. Also, weak evidence suggested shrub establishment was better in rockier fields where grass abundance/competition was lower. Multiple lines of evidence suggest reducing grass seed rates below levels typically used in Great Plains restoration would benefit shrubs without substantially impacting grass stand development over the long term. We used

Using Unmanned Aerial Vehicles to Assess Vegetative Cover and Identify Biotic Resources in Sagebrush Steppe Ecosystems: Preliminary Evaluation

Energy Technology Data Exchange (ETDEWEB)

Robert P. Breckenridge

2006-04-01

The Idaho National Laboratory (INL), in conjunction with the University of Idaho, is evaluating novel approaches for using unmanned aerial vehicles (UAVs) as a quicker and safer method for monitoring biotic resources. Evaluating vegetative cover is an important factor in understanding the sustainability of many ecosystems. In assessing vegetative cover, methods that improve accuracy and cost efficiency could revolutionize how biotic resources are monitored on western federal lands. Sagebrush steppe ecosystems provide important habitat for a variety of species, some of which are important indicator species (e.g., sage grouse). Improved methods are needed to support monitoring these habitats because there are not enough resource specialists or funds available for comprehensive ground evaluation of these ecosystems. In this project, two types of UAV platforms (fixed wing and helicopter) were used to collect still-frame imagery to assess cover in sagebrush steppe ecosystems. This paper discusses the process for collecting and analyzing imagery from the UAVs to (1) estimate total percent cover, (2) estimate percent cover for six different types of vegetation, and (3) locate sage grouse based on representative decoys. The field plots were located on the INL site west of Idaho Falls, Idaho, in areas with varying amounts and types of vegetative cover. A software program called SamplePoint developed by the U.S. Department of Agriculture, Agricultural Research Service was used to evaluate the imagery for percent cover for the six vegetation types (bare ground, litter, shrubs, dead shrubs, grasses, and forbs). Results were compared against standard field measurements to assess accuracy.

Effectiveness of prescribed fire to re-establish sagebrush vegetation and ecohydrologic function on woodland-encroached sagebrush steppe, Great Basin, USA

Science.gov (United States)

Williams, C. J.; Pierson, F. B.; Kormos, P.; Al-Hamdan, O. Z.; Nouwakpo, S.; Weltz, M.; Vega, S.; Lindsay, K.

2017-12-01

Range expansion of pinyon (Pinus spp.) and juniper (Juniperus spp.) conifers into sagebrush steppe (Artemisia spp.) communities has imperiled a vast domain in the western US. Encroachment of sagebrush ecosystems by pinyon and juniper conifers has negative ramifications to ecosystem structure and function and delivery of goods and services. Scientists, land management agencies, and private land owners throughout the western US are challenged with selecting from a suite of options to reduce pinyon and juniper woody fuels and re-establish sagebrush steppe structure and function. This study evaluated the effectiveness of prescribed fire to re-establish sagebrush vegetation and ecohydrologic function over a 9 yr period. Nine years post-fire hydrologic and erosion responses reflect the combination of pre-fire site conditions, perennial grass recruitment, delayed litter cover, and inherent site characteristics. Burning initially increased bare ground, runoff, and erosion for well-vegetated areas underneath tree and shrub canopies, but had minimal impact on hydrology and erosion for degraded interspaces between plants. The degraded interspaces were primarily bare ground and exhibited high runoff and erosion rates prior to burning. Initial fire effects persisted for two years, but increased productivity of grasses improved hydrologic function of interspaces over the full 9 yr period. At the hillslope scale, grass recruitment in the intercanopy between trees reduced runoff from rainsplash, sheetflow, and concentrated overland flow at one site, but did not reduce the high levels of runoff and erosion from a more degraded site. In areas formerly occupied by trees (tree zones), burning increased invasive annual grass cover due to fire removal of limited native perennial plants and competition for resources. The invasive annual grass cover had no net effect on runoff and erosion from tree zones however. Runoff and erosion increased in tree zones at the more degraded site due to

Soil macrofauna (invertebrates of Kazakhstanian Stipa lessingiana dry steppe

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Bragina Tatyana М.

2016-12-01

Full Text Available Stipa lessingiana steppes used to be prevalent on the dry Trans-Ural denudation plains, particularly, on the Sub-Ural and the Turgay Plateau. But, most of them have been lost because they were plowed up during the Virgin Land campaign in the second part of 20th century. This paper presents a detailed study of the faunistic composition and the structure of soil-dwelling invertebrate communities (macrofauna of a temperate-dry bunch feather grass steppe in the Turgai Plateau (Northern-Turgai physical-geographical province of steppe Kazakhstan, Kostanay Oblast. The study site is located in the territory of the Naurzum State Nature Reserve, a part of the UNESCO World Heritage site “Saryarka Steppe and Lakes of Northern Kazakhstan”, where remnants of Virgin S. lessingiana steppes have been preserved to the present day. This region is the driest and most continental in climate of all the dry steppes of Kazakhstan. The total abundance and biomass of soil invertebrate communities in the investigated site were lower than in the northern and western steppe areas. Soil invertebrates are among the major components that determine the functioning of terrestrial natural ecosystems.

Short-Term Effects of Changing Precipitation Patterns on Shrub-Steppe Grasslands: Seasonal Watering Is More Important than Frequency of Watering Events.

Science.gov (United States)

Densmore-McCulloch, Justine A; Thompson, Donald L; Fraser, Lauchlan H

2016-01-01

Climate change is expected to alter precipitation patterns. Droughts may become longer and more frequent, and the timing and intensity of precipitation may change. We tested how shifting precipitation patterns, both seasonally and by frequency of events, affects soil nitrogen availability, plant biomass and diversity in a shrub-steppe temperate grassland along a natural productivity gradient in Lac du Bois Grasslands Protected Area near Kamloops, British Columbia, Canada. We manipulated seasonal watering patterns by either exclusively watering in the spring or the fall. To simulate spring precipitation we restricted precipitation inputs in the fall, then added 50% more water than the long term average in the spring, and vice-versa for the fall precipitation treatment. Overall, the amount of precipitation remained roughly the same. We manipulated the frequency of rainfall events by either applying water weekly (frequent) or monthly (intensive). After 2 years, changes in the seasonality of watering had greater effects on plant biomass and diversity than changes in the frequency of watering. Fall watering reduced biomass and increased species diversity, while spring watering had little effect. The reduction in biomass in fall watered treatments was due to a decline in grasses, but not forbs. Plant available N, measured by Plant Root Simulator (PRS)-probes, increased from spring to summer to fall, and was higher in fall watered treatments compared to spring watered treatments when measured in the fall. The only effect observed due to frequency of watering events was greater extractable soil N in monthly applied treatments compared to weekly watering treatments. Understanding the effects of changing precipitation patterns on grasslands will allow improved grassland conservation and management in the face of global climatic change, and here we show that if precipitation is more abundant in the fall, compared to the spring, grassland primary productivity will likely be

Effect of petroleum on decomposition of shrub-grass litters in soil in Northern Shaanxi of China.

Science.gov (United States)

Zhang, Xiaoxi; Liu, Zengwen; Yu, Qi; Luc, Nhu Trung; Bing, Yuanhao; Zhu, Bochao; Wang, Wenxuan

2015-07-01

The impacts of petroleum contamination on the litter decomposition of shrub-grass land would directly influence nutrient cycling, and the stability and function of ecosystem. Ten common shrub and grass species from Yujiaping oil deposits were studied. Litters from these species were placed into litterbags and buried in petroleum-contaminated soil with 3 levels of contamination (slight, moderate and serious pollution with petroleum concentrations of 15, 30 and 45 g/kg, respectively). A decomposition experiment was then conducted in the lab to investigate the impacts of petroleum contamination on litter decomposition rates. Slight pollution did not inhibit the decomposition of any litters and significantly promoted the litter decomposition of Hippophae rhamnoides, Caragana korshinskii, Amorpha fruticosa, Ziziphus jujuba var. spinosa, Periploca sepium, Medicago sativa and Bothriochloa ischaemum. Moderate pollution significantly inhibited litter decomposition of M. sativa, Coronilla varia, Artemisia vestita and Trrifolium repens and significantly promoted the litter decomposition of C. korshinskii, Z. jujuba var. spinosa and P. sepium. Serious pollution significantly inhibited the litter decomposition of H. rhamnoides, A. fruticosa, B. ischaemum and A. vestita and significantly promoted the litter decomposition of Z. jujuba var. spinosa, P. sepium and M. sativa. In addition, the impacts of petroleum contamination did not exhibit a uniform increase or decrease as petroleum concentration increased. Inhibitory effects of petroleum on litter decomposition may hinder the substance cycling and result in the degradation of plant communities in contaminated areas. Copyright © 2015. Published by Elsevier B.V.

Ecophysiological aspects of the interactions between Bromus kopetdaghensis and two nurse shrubs, Astragalus meschedensis and Acantholimon raddeanam in a semiarid rangeland.

Science.gov (United States)

Jankju, M; Maghamnia, A

2010-07-01

Plant-plant interactions are known as the main biotic drivers of the vegetation dynamics. Therefore, understanding such processes is beneficial for the applied vegetation management. The aim of this research was to investigate the type and intensity of plant-plant interaction during the time course of a growth season. We studied ecophysiological aspects of facilitation and competition between two aridland shrubs, A. meschedensis Bunge and A. raddeanam Czernjak and one perennial grass, B. kopetdaghensis Krasch. Soil and plant sampling were carried out for shrubs and the grass that were either growing alone or the grass was growing under the canopy of shrubs. In Spring (May), soil humidity weight was higher under the shrubs+grass than the grass-only site. By the beginning of Summer (July) grass consumed the common soil water and rapidly terminated its yearly growth. Therefore, in August and September, soil humidity weight was lower under the shrubs+grass than shrub-only sites. Photosynthesis rate of B. kopetdaghensis was sharply reduced from the beginning towards the end of growth season, but was not varied between the different plant combinations. Leaf proline measurement in July indicated higher stress for B. kopetdaghensis that were growing under shrubs than those of open areas. In conclusion, we found facilitation effects of shrubs on the grass at the early times of growth season, but it shifted into the competition for water during summer times. The outcome of plant interaction was positive for the grass but negative for the shrubs, especially A. meschedensis.

Invasive species in the flora of the Starobilsk grass-meadow steppe (Ukraine

Directory of Open Access Journals (Sweden)

Kucher Oksana O.

2015-06-01

Full Text Available The results of an investigation of the invasive species in the flora of the Starobilsk grass-meadow steppe are presented. Check-list of alien plant has over 386 species of vascular plants of which 28 species are invasive. We have identified 6 transformer species from the invasive plants. We aggregate data on the entry, distribution history, ecology, occurrence in different plant communities, degree of their naturalization and the habitats where they occur. The leading families of invasive species are: Asteraceae. The basis for this group is presented by origin from the North America and the Mediterranean. With respect to the time of immigration, most of them are kenophytes. By the method of introduction, ksenophytes are dominated; according to the degree of naturalization epoecophytes and agriophytes dominate in this group. With regard to the characteristics of life forms, half of invasive species are terophytes. The vast majority of plants are heliophytes and xeromesophytes. Most species are found in biotopes group I: Cultivated agricultural biotopes; least of all species found in biotopes group F: Biotopes dominated by chamephytes and nanophanerophytes. Only 3 species found in biotopes group F: Biotopes dominated by chamephytesand nanophanerophytes. The maps of distribution of 28 invasive species are provided. Most of the species marked dispersed in more than 30 squares.

Steppe of Tbilisi environs (East Georgia, South Caucasus

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N.J. Lachashvili

2017-09-01

Full Text Available Steppes of Tbilisi environs are studied. In the Tbilisi surroundings the steppe vegetation is either of primary or secondary origin. Steppe vegetation in the Tbilisi environs are represented by 4 formations: (1 Bothriochloeta ischaemum, (2 Festuceta valesiaci, (3 Stipeta pennatae and (4 Gramino-Mixtoherbeta. From them Bothriochloeta ischaemum and Festuceta valesiaci formations have more area covering and characterized by the comparatively rich typological composition. Typological composition of each formation is established. For each separated plant communities the basic structural characteristics (general projective coverage, sodding degree, dominant-edificatory plant, characteristic species, number of species, moss cover, litter, species richness, spectrum of life forms, distribution area in the Tbilisi environs and main physical-geographical conditions (altitude, exposure, inclination, soil type are given.

Ground beetles (Coleoptera, Carabidae) of the Hanford Nuclear Site in south-central Washington State.

Science.gov (United States)

Looney, Chris; Zack, Richard S; Labonte, James R

2014-01-01

Carabidae) collected from the Hanford Nuclear Reservation and Hanford National Monument (together the Hanford Site), which is located in south-central Washington State. The Site is a relatively undisturbed relict of the shrub-steppe habitat present throughout much of the western Columbia Basin before the westward expansion of the United States. Species, localities, months of capture, and capture method are reported for field work conducted between 1994 and 2002. Most species were collected using pitfall traps, although other capture methods were employed. Trapping results indicate the Hanford Site supports a diverse ground beetle community, with over 90% of the 92 species captured native to North America. Four species collected during the study period are newly recorded for Washington State: Bembidion diligens Casey, Calosoma obsoletum Say, Pseudaptinus rufulus (LeConte), and Stenolophus lineola (Fabricius). Based on these data, the Site maintains a diverse ground beetle fauna and, due to its size and diversity of habitats, is an important repository of shrub-steppe biodiversity.

Herbaceous energy crops in humid lower South USA

Energy Technology Data Exchange (ETDEWEB)

Prine, G.M.; Woodard, K.R. [Univ. of Florida, Gainesville, FL (United States)

1993-12-31

The humid lower South has the long warm growing season and high rainfall conditions needed for producing high-yielding perennial herbaceous grasses and shrubs. Many potential biomass plants were evaluated during a ten-year period. Perennial tall grasses such as elephantgrass (Pennisetum purpureum), sugarcane and energycane (Saccharum spp.) and the leguminous shrub Leucaena leucocephala were the highest in biomass production. These perennial crops often have top growth killed by winter freezes and regenerate from underground parts. The tall grasses have high yields because of linear crop growth rates of 18 to 27 g m{sup 2} d{sup {minus}1} for long periods (140 to 196 d) each season. Tall grasses must be planted vegetatively, which is more costly than seed propagation, however, once established, they may persist for many seasons. Oven dry biomass yields have varied from 20 to 45 Mg ha{sup {minus}1} yr{sup {minus}1} in colder subtropical to mild temperate locations to over 60 Mg ha{sup {minus}1} yr{sup {minus}1} in the lower portion of the Florida peninsular. Highest biomass yields have been produced when irrigated with sewage effluent or when grown on phosphatic clay and muck soils in south Florida. The energy content of 1 Mg of oven dry tall grass and leucaena is equivalent to that of about 112 and 123 gallons of number 2 diesel fuel, respectively.

Using survival analysis of artificial and Real Brewer's sparrow (Spizella breweri breweri) nests to model site level and nest site factors associated with nest success in the South Okanagan region of Canada

Science.gov (United States)

Pam Krannitz Kym Welstead

2005-01-01

Predation is the predominant cause of nest failure for the Brewer's Sparrow (Spizella breweri breweri), a provincially red-listed shrub-steppe species that has experienced significant declines throughout most of its range. We monitored Brewer’s Sparrow nests and conducted an artificial nest experiment, in the South Okanagan Valley,...

Bumble bee (Hymenoptera: Apidae) community structure on two sagebrush steppe sites in southern Idaho

Science.gov (United States)

Stephen P. Cook; Sara M. Birch; Frank W. Merickel; Carrie Caselton Lowe; Deborah Page-Dumroese

2011-01-01

Although sagebrush, Artemisia spp., does not require an insect pollinator, there are several native species of bumble bees, Bombus spp. (Hymenoptera: Apidae), that are present in sagebrush steppe ecosystems where they act as pollinators for various forbs and shrubs. These native pollinators contribute to plant productivity and reproduction. We captured 12 species of...

Females engage in stronger relationships: positive and negative effects of shrubs are more intense for Poa ligularis females than for males.

Science.gov (United States)

Graff, Pamela; Aguiar, Martin R; Almeida, Rocio J

2018-05-22

Dioecious plants are of particular concern in view of global environmental changes because reproductive females are more sensitive to abiotic stresses, thus compromising population viability. Positive interactions with other plants may counteract the direct effects of any abiotic environmental stress, allowing them to thrive and maintain a viable population in suboptimal habitats, although this process has not been tested for dioecious species. Furthermore, almost no data are available on the outcome of such species interactions and their link with local spatial patterns and sex ratios. We set up a field experiment with Poa ligularis, a dioecious native grass from the arid grasslands of South America. We studied the interaction of male and female plants with cushion shrubs of contrasting ecological strategies. We experimentally limited direct shrub-grass competition for soil moisture and transplanted plants to evaluate the amelioration of abiotic stress by shrub canopies (i.e. sun and wind) on grasses. We also studied the distribution of naturally established female and male plants to infer process-pattern relationships. Positive canopy effects as well as negative below-ground effects were more intense for females than for males. Deep-rooted Mulinum spinosum shrubs strongly facilitated survival, growth and reproduction of P. ligularis females. Naturally established female plants tended to distribute more closely to Mulinum than co-occurring males. Female growth suffered intensive negative root competition from the shallow-rooted Senecio filaginoides shrub. Interactions with other plants may reduce or enhance the effect of abiotic stresses on the seemingly maladapted sex to arid environments. We found that these biased interactions are evident in the current organization of sexes in the field, confirming our experimental findings. Therefore, indirect effects of climate change on population sex ratios may be expected if benefactor species abundances are

Ground beetles (Coleoptera, Carabidae of the Hanford Nuclear Site in south-central Washington State

Directory of Open Access Journals (Sweden)

Chris Looney

2014-04-01

Full Text Available In this paper we report on ground beetles (Coleoptera: Carabidae collected from the Hanford Nuclear Reservation and Hanford National Monument (together the Hanford Site, which is located in south-central Washington State. The Site is a relatively undisturbed relict of the shrub-steppe habitat present throughout much of the western Columbia Basin before the westward expansion of the United States. Species, localities, months of capture, and capture method are reported for field work conducted between 1994 and 2002. Most species were collected using pitfall traps, although other capture methods were employed. Trapping results indicate the Hanford Site supports a diverse ground beetle community, with over 90% of the 92 species captured native to North America. Four species collected during the study period are newly recorded for Washington State: Bembidion diligens Casey, Calosoma obsoletum Say, Pseudaptinus rufulus (LeConte, and Stenolophus lineola (Fabricius. Based on these data, the Site maintains a diverse ground beetle fauna and, due to its size and diversity of habitats, is an important repository of shrub-steppe biodiversity.

Bidirectional recovery patterns of Mojave Desert vegetation in an aqueduct pipeline corridor after 36 years: I. Perennial shrubs and grasses

Science.gov (United States)

Berry, Kristin H.; Weigand, James F.; Gowan, Timothy A.; Mack, Jeremy S.

2015-01-01

We studied recovery of 21 perennial plant species along a severely disturbed aqueduct corridor in a Larrea tridentata-Ambrosia dumosa plant alliance in the Mojave Desert 36 years after construction. The 97-m wide corridor contained a central dirt road and buried aqueduct pipeline. We established transects at 0 m (road verge), 20 m and 40 m into the disturbance corridor, and at 100 m in undisturbed habitat (the control). Although total numbers of shrubs per transect did not vary significantly with distance from the verge, canopy cover of shrubs, species richness, and species diversity were higher in the control than at the verge and other distances. Canopy cover of common shrubs (Ericameria nauseosa, Ambrosia salsola, A. dumosa, L. tridentata, Grayia spinosa) and perennial grasses (Elymus elymoides, Poa secunda) also varied significantly by location. Discriminant analysis clearly separated the four distances based on plant composition. Patterns of recovery were bidirectional: secondary succession from the control into the disturbance corridor and inhibition from the verge in the direction of the control. Time estimated for species composition to resemble the control is dependent on location within the disturbance corridor and could be centuries at the road verge. Our findings have applications to other deserts.

Changes in Nitrogen Cycling in a Shrub-Encroached Dryland

Science.gov (United States)

Turpin-Jelfs, T. C.; Michaelides, K.; Biederman, J. A.; Evershed, R. P.; Anesio, A. M.

2017-12-01

Land degradation is estimated to have occurred in 10-20% of Earth's drylands, where the environmental and socioeconomic consequences have affected 250 million people. The prevailing form of land degradation in drylands over the past ca. 150 years has been the encroachment of woody plants into arid and semi-arid grasslands. The density of mesquite (Prosopis spp.), a significant nitrogen (N)-fixing woody encroacher, has increased within the arid and semi-arid grasslands of the southwestern US by >400% over the past 30 years to occupy an area of >38 Mha. However, the impacts of an increasing density of N-fixing shrubs on the cycling and spatial variability of N within these ecosystems remains poorly understood. Here, we quantify how concentrations of N (ammonium-N, nitrate-N, organic N), as well as carbon (C; total C and organic C) and phosphorous (P; loosely-bound P, iron- and aluminium-bound P, apatite P and calcite-bound P, and residual P), and the structure of the microbial community (phospholipid fatty acids), change in the soils underneath and between shrub canopies along a gradient of shrub-encroachment for a semiarid grassland in the Santa Rita Experimental Range (SRER) Arizona, US. This gradient of encroachment was comprised of five sites that ranged from a grass dominated state to a shrub-dominated state characterised by mosaics of shrub patches and bare-soil interspaces. Our results show that the organic C and total N content of soils between shrubs decreased by >50% between grass dominant and shrub dominant end-member sites. Conversely, the organic C and total N content of soils beneath shrub canopies remained relatively constant along the encroachment gradient.

Current stage of the restoration of Chernozems in rangeland ecosystems of the steppe zone

Science.gov (United States)

Rusanov, A. M.

2015-06-01

The results of two rounds of soil and geobotanic surveys of rangeland ecosystems in the steppe zone are presented. The same sites with southern chernozems (Calcic Chernozems) under steppe plant communities at different stages of pasture degradation were investigated at the end of the 1980s, when they suffered maximum anthropogenic loads, and in 2011-2013, after a long period of relative rest. In the 1980s, degradation of soil physical properties in rangeland ecosystems under the impact of long-term unsustainable management was noted. At the same time, it was found that the major qualitative and quantitative properties of humus in the chernozems were preserved independently from the level of pasture degradation. The following period of moderate grazing pressure had a favorable effect on the soil properties. Owing to the good characteristics of the soil humus, the restoration of the physical properties of chernozems-including their structural state, water permeability, and bulk density-took place in a relatively short period. It is argued that the soil bulk density is a natural regulator of the species composition of steppe vegetation, because true grasses (Poaceae)-typical representatives of the steppe flora-have a fibrous root system requiring the soils with low density values. The improvement of the properties of chernozems is related to the development of secondary ecosystems with a higher portion of grasses in place of damaged rangelands and to the increase in the area of nominal virgin phytocenoses.

Fuel buildup and potential fire behavior after stand-replacing fires, logging fire-killed trees and herbicide shrub removal in Sierra Nevada forests

Science.gov (United States)

McGinnis, Thomas W.; Keeley, Jon E.; Stephens, Scott L.; Roller, Gary B.

2010-01-01

Typically, after large stand-replacing fires in mid-elevation Sierra Nevada forests, dense shrub fields occupy sites formerly occupied by mature conifers, until eventually conifers overtop and shade out shrubs. Attempting to reduce fuel loads and expedite forest regeneration in these areas, the USDA Forest Service often disrupts this cycle by the logging of fire-killed trees, replanting of conifers and killing of shrubs. We measured the effects of these treatments on live and dead fuel loads and alien species and modeled potential fire behavior and fire effects on regenerating forests. Sampling occurred in untreated, logged and herbicide-treated stands throughout the Sierra Nevada in four large fire areas 4–21 years after stand-replacing fires. Logging fire-killed trees significantly increased total available dead fuel loads in the short term but did not affect shrub cover, grass and forb cover, alien species cover or alien species richness. Despite the greater available dead fuel loads, fire behavior was not modeled to be different between logged and untreated stands, due to abundant shrub fuels in both logged and untreated stands. In contrast, the herbicide treatment directed at shrubs resulted in extremely low shrub cover, significantly greater alien species richness and significantly greater alien grass and forb cover. Grass and forb cover was strongly correlated with solar radiation on the ground, which may be the primary reason that grass and forb cover was higher in herbicide treated stands with low shrub and tree cover. Repeat burning exacerbated the alien grass problem in some stands. Although modeled surface fire flame lengths and rates of spread were found to be greater in stands dominated by shrubs, compared to low shrub cover conifer plantations, surface fire would still be intense enough to kill most trees, given their small size and low crown heights in the first two decades after planting.

Shrub encroachment alters sensitivity of soil respiration to temperature and moisture

Science.gov (United States)

Cable, Jessica M.; Barron-Gafford, Greg A.; Ogle, Kiona; Pavao-Zuckerman, Mitchell; Scott, Russell L.; Williams, David G.; Huxman, Travis E.

2012-03-01

A greater abundance of shrubs in semiarid grasslands affects the spatial patterns of soil temperature, moisture, and litter, resulting in fertile islands with potentially enhanced soil metabolic activity. The goal of this study was to quantify the microsite specificity of soil respiration in a semiarid riparian ecosystem experiencing shrub encroachment. We quantified the response of soil respiration to different microsite conditions created by big mesquite shrubs (near the trunk and the canopy edge), medium-sized mesquite, sacaton bunchgrasses, and open spaces. We hypothesized that soil respiration would be more temperature sensitive and less moisture sensitive and have a greater magnitude in shrub microsites compared with grass and open microsites. Field and incubation soil respiration data were simultaneously analyzed in a Bayesian framework to quantify the microsite-specific temperature and moisture sensitivities and magnitude of respiration. The analysis showed that shrub expansion increases the heterogeneity of respiration. Respiration has greater temperature sensitivity near the shrub canopy edge, and respiration rates are higher overall under big mesquite compared with those of the other microsites. Respiration in the microsites beneath medium-sized mesquites does not behave like a downscaled version of big mesquite microsites. The grass microsites show more similarity to big mesquite microsites than medium-sized shrubs. This study shows there can be a great deal of fine-scale spatial heterogeneity that accompanies shifts in vegetation structure. Such complexity presents a challenge in scaling soil respiration fluxes to the landscape for systems experiencing shrub encroachment, but quantifying this complexity is significantly important in determining overall ecosystem metabolic behavior.

Trends in soil erosion and woody shrub encroachment in Ngqushwa district, Eastern Cape Province, South Africa.

Science.gov (United States)

Manjoro, Munyaradzi; Kakembo, Vincent; Rowntree, Kate M

2012-03-01

Woody shrub encroachment severely impacts on the hydrological and erosion response of rangelands and abandoned cultivated lands. These processes have been widely investigated at various spatial scales, using mostly field experimentation. The present study used remote sensing to investigate spatial and temporal patterns of soil erosion and encroachment by a woody shrub species, Pteronia incana, in a catchment in Ngqushwa district, Eastern Cape Province, South Africa between 1998 and 2008. The extreme categories of soil erosion and shrub encroachment were mapped with higher accuracy than the intermediate ones, particularly where lower spatial resolution data were used. The results showed that soil erosion in the worst category increased simultaneously with dense woody shrub encroachment on the hill slopes. This trend is related to the spatial patterning of woody shrub vegetation that increases bare soil patches--leading to runoff connectivity and concentration of overland flow. The major changes in soil erosion and shrub encroachment analysed during the 10-year period took place in the 5-9° slope category and on the concave slope form. Multi-temporal analyses, based on remote sensing, can extend our understanding of the dynamics of soil erosion and woody shrub encroachment. They may help benchmark the processes and assist in upscaling field studies.

Chapter 23. Shrubs of other families

Science.gov (United States)

Stephen B. Monsen; Richard Stevens; Nancy L. Shaw

2004-01-01

Numerous genera and species of shrubs occur throughout the Intermountain region in addition to those included in the Asteraceae, Chenopodiaceae, and Rosaceae families. Although shrubs are widespread throughout this region and dominate many areas, species richness is low compared to the shrub flora of the Pacific United States, Chile, western Australia, and South Africa...

Photosynthetic pathways and the geographical distribution of grasses in South West Africa/Namibia

International Nuclear Information System (INIS)

Ellis, R.P.; Vogel, J.C.; Fuls, A.

1980-01-01

Analysis of floristic lists for South West Africa/Namibia shows that, throughout the territory, more than 95% of the grass species occurring in any given area display the C 4 photosynthetic pathway. Exceptions are areas in the north-east and southwest where between 5% and 18% of the grass species are of the C 3 type. The south-western district of Luderitz falls within the winter rainfall area and it is only here that temperate C 3 genera are found. The C 3 species in the north-east belong to tropical groups. Most of the South West African C 3 grasses grow in specialized habitats and are either hydrophytes or sciophytes. Subdivision of the C 4 grasses into the three subtypes of the C 4 pathway reveals distinctive distributional trends. Malate formers or NADP-me species clearly become more abundant with increasing rainfall, whereas the aspartate formers show the opposite tendency. However, within the aspartate forming group the results show that it is specifically the NAD-me type of species which dominate in areas of very low precipitation, notably in the Namib and pre-Namib areas where rainfall is less than 200 mm/yr. The PEP-ck species form a group intermediate between the malate formers and the NAD-me grasses, especially as far as their water requirements are concerned [af

Photosynthetic pathways and the geographical distribution of grasses in South West Africa/Namibia

Energy Technology Data Exchange (ETDEWEB)

Ellis, R P [Department of Agriculture and Fisheries, Pretoria (South Africa). Botanical Research Institute; Vogel, J C; Fuls, A [Council for Scientific and Industrial Research, Pretoria (South Africa). National Physical Research Lab.

1980-07-01

Analysis of floristic lists for South West Africa/Namibia shows that, throughout the territory, more than 95% of the grass species occurring in any given area display the C/sub 4/ photosynthetic pathway. Exceptions are areas in the north-east and southwest where between 5% and 18% of the grass species are of the C/sub 3/ type. The south-western district of Luderitz falls within the winter rainfall area and it is only here that temperate C/sub 3/ genera are found. The C/sub 3/ species in the north-east belong to tropical groups. Most of the South West African C/sub 3/ grasses grow in specialized habitats and are either hydrophytes or sciophytes. Subdivision of the C/sub 4/ grasses into the three subtypes of the C/sub 4/ pathway reveals distinctive distributional trends. Malate formers or NADP-me species clearly become more abundant with increasing rainfall, whereas the aspartate formers show the opposite tendency. However, within the aspartate forming group the results show that it is specifically the NAD-me type of species which dominate in areas of very low precipitation, notably in the Namib and pre-Namib areas where rainfall is less than 200 mm/yr. The PEP-ck species form a group intermediate between the malate formers and the NAD-me grasses, especially as far as their water requirements are concerned.

Surface Runoff and Snowmelt Infiltration into the Soil on Plowlands in the Forest-Steppe and Steppe Zones of the East European Plain

Science.gov (United States)

Barabanov, A. T.; Dolgov, S. V.; Koronkevich, N. I.; Panov, V. I.; Petel'ko, A. I.

2018-01-01

Long-term series of observations over the spring water balance elements on fields with hydrologically contrasting agricultural backgrounds―a loose soil after fall moldboard plowing and a plowland compacted by 12-16% compared to the former soil (perennial grasses, winter crops, stubble)―have been analyzed. The values of surface runoff and water infiltration into the soil in the steppe and forest-steppe zones of European Russia have been calculated for the spring (flooding) period and the entire cold season. The hydrological role of fall plowing has been shown, and water balance elements for the current (1981-2016) and preceding (1957-1980) periods have been compared. A significant decrease in runoff and an increase of water reserve in the soil have been revealed on all plowland types. Consequences of changes in the spring water balance on plowland have been analyzed.

Towards reconstructing herbaceous biome dynamics and associated precipitation in Africa: insights from the classification of grass morphological traits

Science.gov (United States)

Pasturel, Marine; Alexandre, Anne; Novello, Alice; Moctar Dieye, Amadou; Wele, Abdoulaye; Paradis, Laure; Hely, Christelle

2014-05-01

Inter-tropical herbaceous ecosystems occupy a 1/5th of terrestrial surface, a half of the African continent, and are expected to extend in the next decades. Dynamic of these ecosystems is simulated with poor accuracy by Dynamic Global Vegetation Models (DGVMs). One of the bias results from the fact that the diversity of the grass layer dominating these herbaceous ecosystems is poorly taken into account. Mean annual precipitation and the length of the dry season are the main constrains of the dynamics of these ecosystems. Conversely, changes in vegetation affect the water cycle. Inaccuracy in herbaceous ecosystem simulation thus impacts simulations of the water cycle (including precipitation) and vice versa. In order to increase our knowledge of the relationships between grass morphological traits, taxonomy, biomes and climatic niches in Western and South Africa, a 3-step methodology was followed: i) values of culm height, leaf length and width of dominant grass species from Senegal were gathered from flora and clustered using the Partition Around Medoids (PAM) method; ii) trait group ability to sign climatic domains and biomes was assessed using Kruskal-Wallis tests; iii) genericity and robustness of the trait groups were evaluated through their application to Chadian and South African botanical datasets. Results show that 8 grass trait groups are present either in Senegal, Chad or South Africa. These 8 trait groups are distributed along mean annual precipitation and dry season length gradients. The combination of three of them allow to discriminate mean annual precipitation domains (1000 mm) and herbaceous biomes (steppes, savannas, South African grasslands and Nama-Karoo). With these results in hand, grass Plant Functional Types (PFTs) of the DGMV LPJ-GUESS will be re-parameterized and particular attention will be given to the herbaceous biomass assigned to each grass trait group. Simultaneously, relationships between grass trait groups and phytolith vegetation

Legacy effects of no-analogue disturbances alter plant community diversity and composition in semi-arid sagebrush steppe

Science.gov (United States)

Ripplinger, Julie; Franklin, Janet; Edwards, Thomas C.

2015-01-01

Questions(i) What role does the type of managed disturbance play in structuring sagebrush steppe plant communities? (ii) How does the composition of post-disturbance plant communities change with time since disturbance? (iii) Does plant community diversity change over time following managed disturbance?LocationField study within the sagebrush steppe ecosystem. Rich County, Utah, USA.MethodsWe developed a chronosequence spanning up to 50 yrs post-treatment to study sagebrush steppe vegetation dynamics. Direct ordination was used to examine plant community composition by managed disturbance type and time since disturbance, and factorial analysis of covariance was used to examine diversity dynamics following disturbance. Indicator species values were calculated in order to identify characteristic species for each disturbance type.ResultsPlant communities experienced a shift toward distinct community composition for each of the three managed disturbance types, and gave no indication of returning to untreated community composition or diversity. Small post-disturbance increases in the number of non-native grass species were observed in the treatments relative to reference, with native forb species making the largest contribution to altered composition. On fire- and chemically-treated sites the proportional native forb species richness increased over time since disturbance, while the proportional contribution of non-native forbs to total species richness decreased. For all three treatment types, native grasses contributed less on average to total richness than on reference sites, while non-native grasses made up a higher proportion of total richness.ConclusionsCommon shrubland management techniques have legacy effects on the composition and diversity of sagebrush steppe plant communities, and no-analogue disturbances, such as chemical or mechanical treatments, have more pronounced legacy effects than treatments similar to natural disturbance regimes (fire). This study

over time

Directory of Open Access Journals (Sweden)

Sara K. Hanna

2015-01-01

Full Text Available Sagebrush steppe ecosystems of the Intermountain West have experienced a decline over the past 150 years due to changing fire regimes, invasive species and conifer encroachment. Prescribed fire is a common and cost-effective tool used in sagebrush restoration and fuels management. We examined the post-fire succession of a sagebrush steppe community over a nearly 30-year period at two study sites in northeastern California. The long-term nature of this study was particularly significant, as invasive annual grasses dominated the plant community in the years immediately following fire, but native perennial grasses and shrubs successfully out-competed them in the long term. Shrubs were slow to recover but had returned to pre-fire levels by the end of the study period. There was also notable increase in western juniper throughout the study sites, particularly in areas that had not been burned. Our results indicate that mean fire return intervals of 50 years or less would help reduce western juniper encroachment and preserve sagebrush habitat, especially for potentially threatened species such as the sage grouse.

Sharp-tailed Grouse and Pygmy Rabbit Wildlife Mitigation Project

International Nuclear Information System (INIS)

1992-10-01

The Proposed Action is needed to protect and enhance shrub-steppe and riparian habitat for sharp-tailed grouse (Tympanuchus phasianellus columbianus), Pygmy rabbits (Brachylagus idahoensis), and other indigenous wildlife species. The purpose of the Proposed Action is to compensate, in part, for wildlife habitat lost from the construction of Grand Coulee Dam and the inundation of Lake Roosevelt. Bonneville Power Administration proposes to fund management agreements, conservation easements, acquisition of fee title, or a combination of these on as many as 29,000 acres in Lincoln and Douglas Counties to improve shrub-steppe and riparian habitat for sharp-tailed grouse and pygmy rabbits. The BPA also proposes to fund habitat improvements (enhancements) on project lands including existing public lands. Proposed habitat treatments would include control of grazing; planting of native trees, shrubs, forbs and grasses; protection of wetlands and streambanks; herbicide use; fire prescriptions; and wildfire suppression. Proposed management activities may include predator control, population introductions, and control of crop depredation

Current ecosystem processes in steppe near Lake Baikal

Science.gov (United States)

Vanteeva, Julia

2015-04-01

herbaceous phytomass of the steppe complexes varied from 0.4 to 2.64 t/ha. Apical stony and sloping grass-forb landscapes and areas of settlements and recreation facilities had the lowest values. Forest steppes were characterized by low crown density, non-large stand density, which was represented mainly by larch. Phytomass stock ranged from 30.78 to 282.24 t/ha. Maximum values corresponded to the forest steppe with larch on steep slopes. The maximum values of the silt matter transfer (up to 124 g /m2) corresponded to areas with a strong recreation pressure with the lower value of vegetation cover (from 0 to 45%) and aboveground herbaceous phytomass (0.4 - 0.6 t/ha). During experiment with using rainfall simulator defined different sensibility to soil erosion, for example, for Caragana steppe with sagebrush on the undisturbed area trapped silt is 12 g/m2 and for anthropogenic disturbed patch - 84 g/m2. For Sagebrush steppe trapped silt changed from 4 to 16 g/m2. The study shows strong landscapes transformation leading to loss of biodiversity, the reduction of phytomass production and water percolation.

The Bering Land Bridge: a moisture barrier to the dispersal of steppe-tundra biota?

Science.gov (United States)

Elias, Scott A.; Crocker, Barnaby

2008-12-01

The Bering Land Bridge (BLB) connected the two principal arctic biological refugia, Western and Eastern Beringia, during intervals of lowered sea level in the Pleistocene. Fossil evidence from lowland BLB organic deposits dating to the Last Glaciation indicates that this broad region was dominated by shrub tundra vegetation, and had a mesic climate. The dominant ecosystem in Western Beringia and the interior regions of Eastern Beringia was steppe-tundra, with herbaceous plant communities and arid climate. Although Western and Eastern Beringia shared many species in common during the Late Pleistocene, there were a number of species that were restricted to only one side of the BLB. Among the vertebrate fauna, the woolly rhinoceros was found only to the west of the BLB, North American camels, bonnet-horned musk-oxen and some horse species were found only to the east of the land bridge. These were all steppe-tundra inhabitants, adapted to grazing. The same phenomenon can be seen in the insect faunas of the Western and Eastern Beringia. The steppe-tundra beetle fauna of Western Beringia was dominated by weevils of the genus Stephanocleonus, a group that was virtually absent from Eastern Beringia. The dry-adapted weevils, Lepidophorus lineaticollis and Vitavitus thulius were important members of steppe-tundra communities in Eastern Beringia, but were either absent or rare in Western Beringia. The leaf beetles Chrysolina arctica, C. brunnicornis bermani, and Galeruca interrupta circumdata were typical members of the Pleistocene steppe-tundra communities of Western Beringia, but absent from Eastern Beringia. On the other hand, some steppe tundra-adapted leaf beetles managed to occupy both sides of the BLB, such as Phaedon armoraciae. Much of the BLB remains unstudied, but on biogeographic grounds, it appears that there was some kind of biological filter that blocked the movements of some steppe-tundra plants and animals across the BLB.

Ecological restoration of peatlands in steppe and forest-steppe areas

Science.gov (United States)

Minayeva, Tatiana; Sirin, Andrey; Dugarjav, Chultem

2016-04-01

Peatlands in the arid and semi-arid regions of steppe and forest steppe belt of Eurasia have some specific features. That demands the special approach to their management and restoration. The distribution of peatlands under conditions of dry climate is very limited and they are extremely vulnerable. Peatlands in those regions are found in the highlands where temperate conditions still present, in floodplains where they can get water from floods and springs, or in karst areas. Peatlands on watersheds present mainly remains from the more humid climate periods. Water and carbon storage as well as maintenance of the specific biodiversity are the key ecosystem natural functions of peatlands in the steppe and forest steppe. The performance of those functions has strong implications for people wellness and livelihood. Anyhow, peatlands are usually overlooked and poorly represented in the systems of natural protected areas. Land management plans, mitigation and restoration measures for ecosystems under use do not usually include special measures for peatlands. Peatlands'use depends on the traditional practices. Peat extraction is rather limited in subhumid regions but still act as one of the threats to peatlands. The most of peatlands are used as pastures and grasslands. In densely populated areas large part of peatlands are transformed to the arable lands. In many cases peatlands of piedmonts and highlands are affected by industrial developments: road construction, mining of subsoil resources (gold, etc.). Until now, the most of peatlands of steppe and forest steppe region are irreversibly lost, what also effects water regime, lands productivity, biodiversity status. To prevent further dramatic changes the ecological restoration approach should be introduced in the subhumid regions. The feasibility study to assess the potential for introducing ecological restoration techniques for peatlands in the arid and semi-arid conditions had been undertaken in steppe and forest

Changes in rainfall amount and frequency do not affect the outcome of the interaction between the shrub Retama sphaerocarpa and its neighbouring grasses in two semiarid communities.

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Soliveres, Santiago; García-Palacios, Pablo; Maestre, Fernando T; Escudero, Adrián; Valladares, Fernando

2013-04-01

We evaluated the net outcome of the interaction between the shrub Retama sphaerocarpa , our target plant, and different herbaceous neighbours in response to changes in the magnitude and frequency of rainfall events during three years. The experiment was conducted in natural and anthropogenic grasslands dominated by a perennial stress-tolerator and ruderal annual species, respectively. In spite of the neutral or positive effects of neighbours on water availability, neighbouring plants reduced the performance of Retama juveniles, suggesting competition for resources other than water. The negative effects of grasses on the photochemical efficiency of Retama juveniles decreased with higher water availabilities or heavier irrigation pulses, depending on the grassland studied; however, these effects did not extent to the survival and growth of Retama juveniles. Our findings show the prevalence of competitive interactions among the studied plants, regardless of the water availability and its temporal pattern. These results suggest that positive interactions may not prevail under harsher conditions when shade-intolerant species are involved. This study could be used to further refine our predictions of how plant-plant interactions will respond to changes in rainfall, either natural or increased by the ongoing climatic change, in ecosystems where grass-shrubs interactions are prevalent.

Changes in rainfall amount and frequency do not affect the outcome of the interaction between the shrub Retama sphaerocarpa and its neighbouring grasses in two semiarid communities

Science.gov (United States)

Soliveres, Santiago; García-Palacios, Pablo; Maestre, Fernando T.; Escudero, Adrián; Valladares, Fernando

2015-01-01

We evaluated the net outcome of the interaction between the shrub Retama sphaerocarpa, our target plant, and different herbaceous neighbours in response to changes in the magnitude and frequency of rainfall events during three years. The experiment was conducted in natural and anthropogenic grasslands dominated by a perennial stress-tolerator and ruderal annual species, respectively. In spite of the neutral or positive effects of neighbours on water availability, neighbouring plants reduced the performance of Retama juveniles, suggesting competition for resources other than water. The negative effects of grasses on the photochemical efficiency of Retama juveniles decreased with higher water availabilities or heavier irrigation pulses, depending on the grassland studied; however, these effects did not extent to the survival and growth of Retama juveniles. Our findings show the prevalence of competitive interactions among the studied plants, regardless of the water availability and its temporal pattern. These results suggest that positive interactions may not prevail under harsher conditions when shade-intolerant species are involved. This study could be used to further refine our predictions of how plant-plant interactions will respond to changes in rainfall, either natural or increased by the ongoing climatic change, in ecosystems where grass-shrubs interactions are prevalent. PMID:25914429

Ecosystem engineering varies spatially: a test of the vegetation modification paradigm for prairie dogs

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Baker, Bruce W.; Augustine, David J.; Sedgwick, James A.; Lubow, Bruce C.

2013-01-01

Colonial, burrowing herbivores can be engineers of grassland and shrubland ecosystems worldwide. Spatial variation in landscapes suggests caution when extrapolating single-place studies of single species, but lack of data and the need to generalize often leads to ‘model system’ thinking and application of results beyond appropriate statistical inference. Generalizations about the engineering effects of prairie dogs (Cynomys sp.) developed largely from intensive study at a single complex of black-tailed prairie dogs C. ludovicianus in northern mixed prairie, but have been extrapolated to other ecoregions and prairie dog species in North America, and other colonial, burrowing herbivores. We tested the paradigm that prairie dogs decrease vegetation volume and the cover of grasses and tall shrubs, and increase bare ground and forb cover. We sampled vegetation on and off 279 colonies at 13 complexes of 3 prairie dog species widely distributed across 5 ecoregions in North America. The paradigm was generally supported at 7 black-tailed prairie dog complexes in northern mixed prairie, where vegetation volume, grass cover, and tall shrub cover were lower, and bare ground and forb cover were higher, on colonies than at paired off-colony sites. Outside the northern mixed prairie, all 3 prairie dog species consistently reduced vegetation volume, but their effects on cover of plant functional groups varied with prairie dog species and the grazing tolerance of dominant perennial grasses. White-tailed prairie dogs C. leucurus in sagebrush steppe did not reduce shrub cover, whereas black-tailed prairie dogs suppressed shrub cover at all complexes with tall shrubs in the surrounding habitat matrix. Black-tailed prairie dogs in shortgrass steppe and Gunnison's prairie dogs C. gunnisoni in Colorado Plateau grassland both had relatively minor effects on grass cover, which may reflect the dominance of grazing-tolerant shortgrasses at both complexes. Variation in modification of

Response of soil methane uptake to simulated nitrogen deposition and grazing management across three types of steppe in Inner Mongolia, China.

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Li, Xianglan; He, Hong; Yuan, Wenping; Li, Linghao; Xu, Wenfang; Liu, Wei; Shi, Huiqiu; Hou, Longyu; Chen, Jiquan; Wang, Zhiping

2018-01-15

The response of soil methane (CH 4 ) uptake to increased nitrogen (N) deposition and grazing management was studied in three types of steppe (i.e., meadow steppe, typical steppe, and desert steppe) in Inner Mongolia, China. The experiment was designed with four simulated N deposition rates such as 0, 50, 100, and 200kgNha -1 , respectively, under grazed and fenced management treatments. Results showed that the investigated steppes were significant sinks for CH 4 , with an uptake flux of 1.12-3.36kgha -1 over the grass growing season and that the magnitude of CH 4 uptake significantly (Prates. The soil CH 4 uptake rates were highest in the desert steppe, moderate in the typical steppe, and lowest in the meadow steppe. Compared with grazed plots, fencing increased the CH 4 uptake by 4.7-40.2% with a mean value of 20.2% across the three different steppe types. The responses of soil CH 4 uptake to N deposition in the continental steppe varied depending on the N deposition rate, steppe type, and grazing management. A significantly positive correlation between CH 4 uptake and soil temperature was found in this study, whereas no significant relationship between soil moisture and CH 4 uptake occurred. Our results may contribute to the improvement of model parameterization for simulating biosphere-atmosphere CH 4 exchange processes and for evaluating the climate change feedback on CH 4 soil uptake. Copyright © 2017 Elsevier B.V. All rights reserved.

[Effects of cutting and reseeding on the ground-dwelling arthropod community in Caragana intermedia forest in desert steppe].

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Liu, Ren-Tao; Chai, Yong-Qing; Yang, Xin-Guo; Song, Nai-Ping; Wang, Xin-Yun; Wang, Lei

2013-01-01

Taking a 25-year-old Caragana intermedia forest in desert steppe as test object, an investigation was conducted on the ground-dwelling arthropod community in cutting and no-cutting stands with and without reseeding, aimed to understand the effects of cutting, reseeding and their interaction on the individual number and group richness of ground-dwelling arthropod in C. intermedia forest. There were significantly lower number and richness of ground-dwelling arthropod in the open spaces than under the shrubs in the no-cutting and no-reseeding stands. Cutting, reseeding and both of them could significantly increase the number and richness of ground-dwelling arthropod in the open spaces, but not under the shrubs, compared with no cutting or reseeding. Consequently, there were no significant differences in the distribution of ground-dwelling arthropod in the open spaces and under the shrubs in the cutting, reseeding, or cutting and reseeding stands. Further, there was a similar buffer effect between cutting and reseeding on the ground-dwelling arthropod. No significant differences were observed in the ground-dwelling arthropod distribution, between cutting stand and reseeding stand, between cutting stand and cutting and reseeding stand, and between reseeding stand and cutting and reseeding stand. It was suggested that cutting, reseeding, or both of them could significantly improve the ground-dwelling arthropod diversity especially in the open spaces, being beneficial for the restoration of degraded grassland ecosystem and the rational management on artificial C. intermedia forest in desert steppe.

Climatic warming strengthens a positive feedback between alpine shrubs and fire.

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Camac, James S; Williams, Richard J; Wahren, Carl-Henrik; Hoffmann, Ary A; Vesk, Peter A

2017-08-01

Climate change is expected to increase fire activity and woody plant encroachment in arctic and alpine landscapes. However, the extent to which these increases interact to affect the structure, function and composition of alpine ecosystems is largely unknown. Here we use field surveys and experimental manipulations to examine how warming and fire affect recruitment, seedling growth and seedling survival in four dominant Australian alpine shrubs. We found that fire increased establishment of shrub seedlings by as much as 33-fold. Experimental warming also doubled growth rates of tall shrub seedlings and could potentially increase their survival. By contrast, warming had no effect on shrub recruitment, postfire tussock regeneration, or how tussock grass affected shrub seedling growth and survival. These findings indicate that warming, coupled with more frequent or severe fires, will likely result in an increase in the cover and abundance of evergreen shrubs. Given that shrubs are one of the most flammable components in alpine and tundra environments, warming is likely to strengthen an existing feedback between woody species abundance and fire in these ecosystems. © 2017 John Wiley & Sons Ltd.

Reclamation after oil and gas development does not speed up succession or plant community recovery in big sagebrush ecosystems in Wyoming

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Rottler, Caitlin M.; Burke, Ingrid C.; Palmquist, Kyle A.; Bradford, John B.; Lauenroth, William K.

2018-01-01

Article for intended outlet: Restoration Ecology. Abstract: Reclamation is an application of treatment(s) following a disturbance to promote succession and accelerate the return of target conditions. Previous studies have framed reclamation in the context of succession by studying its effectiveness in re-establishing late-successional plant communities. Re-establishment of these plant communities is especially important and potentially challenging in regions such as drylands and shrub steppe ecosystems where succession proceeds slowly. Dryland shrub steppe ecosystems are frequently associated with areas rich in fossil-fuel energy sources, and as such the need for effective reclamation after disturbance from fossil-fuel-related energy development is great. Past research in this field has focused primarily on coal mines; few researchers have studied reclamation after oil and gas development. To address this research gap and to better understand the effect of reclamation on rates of succession in dryland shrub steppe ecosystems, we sampled oil and gas wellpads and adjacent undisturbed big sagebrush plant communities in Wyoming, USA and quantified the extent of recovery for major functional groups on reclaimed and unreclaimed (recovered via natural succession) wellpads relative to the undisturbed plant community. Reclamation increased the rate of recovery for all forb and grass species as a group and for perennial grasses, but did not affect other functional groups. Rather, analyses comparing recovery to environmental variables and time since wellpad abandonment showed that recovery of other groups were affected primarily by soil texture and time since wellpad abandonment. This is consistent with studies in other ecosystems where reclamation has been implemented, suggesting that reclamation may not help re-establish late-successional plant communities more quickly than they would re-establish naturally.

Impacts of informal trails on vegetation and soils in the highest protected area in the Southern Hemisphere.

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Barros, Agustina; Gonnet, Jorge; Pickering, Catherine

2013-09-30

There is limited recreation ecology research in South America, especially studies looking at informal trails. Impacts of informal trails formed by hikers and pack animals on vegetation and soils were assessed for the highest protected area in the Southern Hemisphere, Aconcagua Provincial Park. The number of braided trails, their width and depth were surveyed at 30 sites along the main access route to Mt Aconcagua (6962 m a.s.l.). Species composition, richness and cover were also measured on control and trail transects. A total of 3.3 ha of alpine meadows and 13.4 ha of alpine steppe were disturbed by trails. Trails through meadows resulted in greater soil loss, more exposed soil and rock and less vegetation than trails through steppe vegetation. Trampling also affected the composition of meadow and steppe vegetation with declines in sedges, herbs, grasses and shrubs on trails. These results highlight how visitor use can result in substantial cumulative damage to areas of high conservation value in the Andes. With unregulated use of trails and increasing visitation, park agencies need to limit the further spread of informal trails and improve the conservation of plant communities in Aconcagua Provincial Park and other popular parks in the region. Copyright © 2013 Elsevier Ltd. All rights reserved.

Biological recovery the steppe of Hammada scoparia after enclosure in the region of Naama (Algeria

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Boucherit Hafidha

2017-03-01

Full Text Available This work was being carried out in the steppe of remth (Hammada scoparia in Oranian part of the Saharan Atlas (Tiout - south of Naama. The H. scoparia of Saharan group occupies the foothills south of the Saharan Atlas and glazes and hamadas of the northern part of the Sahara where it seems to find its optimum development. The objective of the study is the floristic and ecological characterisation of the steppe vegetation groups of H. scoparia after 4 years of enclosure grazing (Eg. For the past three decades, steppe of H. scoparia were completely overwhelmed, both in their structure and their operation by increasing the herd and the continued use of natural pastures using animal load significantly higher than the production potential of course, which is reflected by the reduction of their capacity for natural regeneration.

Transcriptome Analysis in Sheepgrass (Leymus chinensis). A Dominant Perennial Grass of the Eurasian Steppe

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Chen, Shuangyan [Chinese Academy of Sciences (CAS), Institute of Botany (IB), Beijing; Huang, Xin [Chinese Academy of Sciences (CAS), Institute of Botany (IB), Beijing; Yang, Xiaohan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liu, Gongshe [Chinese Academy of Sciences (CAS), Institute of Botany (IB), Beijing

2013-07-04

BACKGROUND: Sheepgrass [Leymus chinensis (Trin.) Tzvel.] is an important perennial forage grass across the Eurasian Steppe and is known for its adaptability to various environmental conditions. However, insufficient data resources in public databases for sheepgrass limited our understanding of the mechanism of environmental adaptations, gene discovery and molecular marker development. RESULTS: The transcriptome of sheepgrass was sequenced using Roche 454 pyrosequencing technology. We assembled 952,328 high-quality reads into 87,214 unigenes, including 32,416 contigs and 54,798 singletons. There were 15,450 contigs over 500 bp in length. BLAST searches of our database against Swiss-Prot and NCBI non-redundant protein sequences (nr) databases resulted in the annotation of 54,584 (62.6%) of the unigenes. Gene Ontology (GO) analysis assigned 89,129 GO term annotations for 17,463 unigenes. We identified 11,675 core Poaceae-specific and 12,811 putative sheepgrass-specific unigenes by BLAST searches against all plant genome and transcriptome databases. A total of 2,979 specific freezing-responsive unigenes were found from this RNAseq dataset. We identified 3,818 EST-SSRs in 3,597 unigenes, and some SSRs contained unigenes that were also candidates for freezing-response genes. Characterizations of nucleotide repeats and dominant motifs of SSRs in sheepgrass were also performed. Similarity and phylogenetic analysis indicated that sheepgrass is closely related to barley and wheat. CONCLUSIONS: This research has greatly enriched sheepgrass transcriptome resources. The identified stress-related genes will help us to decipher the genetic basis of the environmental and ecological adaptations of this species and will be used to improve wheat and barley crops through hybridization or genetic transformation. The EST-SSRs reported here will be a valuable resource for future gene-phenotype studies and for the molecular breeding of sheepgrass and other Poaceae species.

Transcriptome analysis in sheepgrass (Leymus chinensis): a dominant perennial grass of the Eurasian Steppe.

Science.gov (United States)

Chen, Shuangyan; Huang, Xin; Yan, Xueqing; Liang, Ye; Wang, Yuezhu; Li, Xiaofeng; Peng, Xianjun; Ma, Xingyong; Zhang, Lexin; Cai, Yueyue; Ma, Tian; Cheng, Liqin; Qi, Dongmei; Zheng, Huajun; Yang, Xiaohan; Li, Xiaoxia; Liu, Gongshe

2013-01-01

Sheepgrass [Leymus chinensis (Trin.) Tzvel.] is an important perennial forage grass across the Eurasian Steppe and is known for its adaptability to various environmental conditions. However, insufficient data resources in public databases for sheepgrass limited our understanding of the mechanism of environmental adaptations, gene discovery and molecular marker development. The transcriptome of sheepgrass was sequenced using Roche 454 pyrosequencing technology. We assembled 952,328 high-quality reads into 87,214 unigenes, including 32,416 contigs and 54,798 singletons. There were 15,450 contigs over 500 bp in length. BLAST searches of our database against Swiss-Prot and NCBI non-redundant protein sequences (nr) databases resulted in the annotation of 54,584 (62.6%) of the unigenes. Gene Ontology (GO) analysis assigned 89,129 GO term annotations for 17,463 unigenes. We identified 11,675 core Poaceae-specific and 12,811 putative sheepgrass-specific unigenes by BLAST searches against all plant genome and transcriptome databases. A total of 2,979 specific freezing-responsive unigenes were found from this RNAseq dataset. We identified 3,818 EST-SSRs in 3,597 unigenes, and some SSRs contained unigenes that were also candidates for freezing-response genes. Characterizations of nucleotide repeats and dominant motifs of SSRs in sheepgrass were also performed. Similarity and phylogenetic analysis indicated that sheepgrass is closely related to barley and wheat. This research has greatly enriched sheepgrass transcriptome resources. The identified stress-related genes will help us to decipher the genetic basis of the environmental and ecological adaptations of this species and will be used to improve wheat and barley crops through hybridization or genetic transformation. The EST-SSRs reported here will be a valuable resource for future gene-phenotype studies and for the molecular breeding of sheepgrass and other Poaceae species.

Arid oil-field restoration: native perennial grasses suppress weeds and erosion, but also suppress native shrubs

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1. Long-lived, drought-tolerant shrubs are dominant components of many arid ecosystems, and shrubs provide multiple ecosystem services (e.g., soil stabilization, herbaceous plant facilitation, carbon storage and wildlife habitat). On denuded sites, shrub restoration is hindered by abiotic (erosion ...

Restoration handbook for sagebrush steppe ecosystems with emphasis on greater sage-grouse habitat—Part 1. Concepts for understanding and applying restoration

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Pyke, David A.; Chambers, Jeanne C.; Pellant, Mike; Knick, Steven T.; Miller, Richard F.; Beck, Jeffrey L.; Doescher, Paul S.; Schupp, Eugene W.; Roundy, Bruce A.; Brunson, Mark; McIver, James D.

2015-10-26

Sagebrush steppe ecosystems in the United States currently occur on only about one-half of their historical land area because of changes in land use, urban growth, and degradation of land, including invasions of non-native plants. The existence of many animal species depends on the existence of sagebrush steppe habitat. The greater sage-grouse (Centrocercus urophasianus) is a landscape-dependent bird that requires intact habitat and combinations of sagebrush and perennial grasses to exist. In addition, other sagebrush-obligate animals also have similar requirements and restoration of landscapes for greater sage-grouse also will benefit these animals. Once sagebrush lands are degraded, they may require restoration actions to make those lands viable habitat for supporting sagebrushobligate animals. This restoration handbook is the first in a three-part series on restoration of sagebrush ecosystems. In Part 1, we discuss concepts surrounding landscape and restoration ecology of sagebrush ecosystems and greater sage-grouse that habitat managers and restoration practitioners need to know to make informed decisions regarding where and how to restore specific areas. We will describe the plant dynamics of sagebrush steppe ecosystems and their responses to major disturbances, fire, and defoliation. We will introduce the concepts of ecosystem resilience to disturbances and resistance to invasions of annual grasses within sagebrush steppe. An introduction to soils and ecological site information will provide insights into the specific plants that can be restored in a location. Soil temperature and moisture regimes are described as a tool for determining resilience and resistance and the potential for various restoration actions. Greater sage-grouse are considered landscape birds that require large areas of intact sagebrush steppe; therefore, we describe concepts of landscape ecology that aid our decisions regarding habitat restoration. We provide a brief overview of

Biophysics environmental conditions of swamp buffalo Bubalus bubalis Pampangan in district Rambutan South Sumatera

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Yuanita Windusari

2015-06-01

Full Text Available Swamp buffalo (Bubalus bubalis is a germ plasm specific of Pampangan and endemic in South Sumatera with low productivity and limited distribution. The aims of this study was to obtain information regarding biophysical conditions in the central areas of swamp buffalo in South Sumatera. The method used is purposive sampling method. Data collected in the form of quantitative and qualitative. Primary data were obtained through direct observation, interviews breeders selected as respondents while secondary data obtained from various related. The data obtained are presented descriptively and data tabulation. Productivity of swamp buffalo Pampangan can be increased by managing and maintaining habitat conditions although traditional maintenance. The results of observations of the biophysical condition of swamp buffalo (B. bubalis Pampangan showed that habitat of swamp buffalo Pampangan consists of dominated by lowland swamp area is overgrown with shrubs and grass. The conclution of the research are productivity and population of swamp buffalo (B. bubalis pampangan as specific plasma nutfah of South Sumatra can be improved by studying the characteristics and preferred habitat of the buffalo, although developed in a traditional farms but is good enough and so need to be developed, grass is most preferred by swamp buffalo Pampangan derived from ‘Kumpai’ grass group, and ‘Kasur’grass and ‘Kumpai’ grass is the dominant grass type found in habitat swamp buffalo Pampangan.

Weak interspecific interactions in a sagebrush steppe? Conflicting evidence from observations and experiments.

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Adler, Peter B; Kleinhesselink, Andrew; Giles, Hooker; Taylor, J Bret; Teller, Brittany; Ellner, Stephen P

2018-04-28

Stable coexistence requires intraspecific limitations to be stronger than interspecific limitations. The greater the difference between intra- and interspecific limitations, the more stable the coexistence, and the weaker the competitive release any species should experience following removal of competitors. We conducted a removal experiment to test whether a previously estimated model, showing surprisingly weak interspecific competition for four dominant species in a sagebrush steppe, accurately predicts competitive release. Our treatments were 1) removal of all perennial grasses and 2) removal of the dominant shrub, Artemisia tripartita. We regressed survival, growth and recruitment on the locations, sizes, and species identities of neighboring plants, along with an indicator variable for removal treatment. If our "baseline" regression model, which accounts for local plant-plant interactions, accurately explains the observed responses to removals, then the removal coefficient should be non-significant. For survival, the removal coefficients were never significantly different from zero, and only A. tripartita showed a (negative) response to removals at the recruitment stage. For growth, the removal treatment effect was significant and positive for two species, Poa secunda and Pseudoroegneria spicata, indicating that the baseline model underestimated interspecific competition. For all three grass species, population models based on the vital rate regressions that included removal effects projected 1.4 to 3-fold increases in equilibrium population size relative to the baseline model (no removal effects). However, we found no evidence of higher response to removal in quadrats with higher pretreatment cover of A. tripartita, or by plants experiencing higher pre-treatment crowding by A. tripartita, raising questions about the mechanisms driving the positive response to removal. While our results show the value of combining observations with a simple removal experiment

Land use and habitat conditions across the southwestern Wyoming sagebrush steppe: development impacts, management effectiveness and the distribution of invasive plants

Science.gov (United States)

Manier, Daniel J.; Aldridge, Cameron L.; Anderson, Patrick; Chong, Geneva; Homer, Collin G.; O'Donnell, Michael S.; Schell, Spencer

2011-01-01

For the past several years, USGS has taken a multi-faceted approach to investigating the condition and trends in sagebrush steppe ecosystems. This recent effort builds upon decades of work in semi-arid ecosystems providing a specific, applied focus on the cumulative impacts of expanding human activities across these landscapes. Here, we discuss several on-going projects contributing to these efforts: (1) mapping and monitoring the distribution and condition of shrub steppe communities with local detail at a regional scale, (2) assessing the relationships between specific, land-use features (for example, roads, transmission lines, industrial pads) and invasive plants, including their potential (environmentally defined) distribution across the region, and (3) monitoring the effects of habitat treatments on the ecosystem, including wildlife use and invasive plant abundance. This research is focused on the northern sagebrush steppe, primarily in Wyoming, but also extending into Montana, Colorado, Utah and Idaho. The study area includes a range of sagebrush types (including, Artemisia tridentata ssp. tridentata, Artemisia tridentata ssp. wyomingensis, Artemisia tridentata ssp. vaseyana, Artemisia nova) and other semi-arid shrubland types (for example, Sarcobatus vermiculatus, Atriplex confertifolia, Atriplex gardneri), impacted by extensive interface between steppe ecosystems and industrial energy activities resulting in a revealing multiple-variable analysis. We use a combination of remote sensing (AWiFS (1 Any reference to platforms, data sources, equipment, software, patented or trade-marked methods is for information purposes only. It does not represent endorsement of the U.S.D.I., U.S.G.S. or the authors), Landsat and Quickbird platforms), Geographic Information System (GIS) design and data management, and field-based, replicated sampling to generate multiple scales of data representing the distribution of shrub communities for the habitat inventory. Invasive plant

Antecedent conditions influence soil respiration differences in shrub and grass patches

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Quantifying the response of soil respiration to past environmental conditions is critical for predicting how future climate and vegetation change will impact ecosystem carbon balance. Increased shrub dominance in semiarid grasslands has potentially large effects on soil carbon cycling. The goal of t...

Long-term nitrogen addition leads to loss of species richness due to litter accumulation and soil acidification in a temperate steppe.

Science.gov (United States)

Fang, Ying; Xun, Fen; Bai, Wenming; Zhang, Wenhao; Li, Linghao

2012-01-01

Although community structure and species richness are known to respond to nitrogen fertilization dramatically, little is known about the mechanisms underlying specific species replacement and richness loss. In an experiment in semiarid temperate steppe of China, manipulative N addition with five treatments was conducted to evaluate the effect of N addition on the community structure and species richness. Species richness and biomass of community in each plot were investigated in a randomly selected quadrat. Root element, available and total phosphorus (AP, TP) in rhizospheric soil, and soil moisture, pH, AP, TP and inorganic N in the soil were measured. The relationship between species richness and the measured factors was analyzed using bivariate correlations and stepwise multiple linear regressions. The two dominant species, a shrub Artemisia frigida and a grass Stipa krylovii, responded differently to N addition such that the former was gradually replaced by the latter. S. krylovii and A. frigida had highly-branched fibrous and un-branched tap root systems, respectively. S. krylovii had higher height than A. frigida in both control and N added plots. These differences may contribute to the observed species replacement. In addition, the analysis on root element and AP contents in rhizospheric soil suggests that different calcium acquisition strategies, and phosphorus and sodium responses of the two species may account for the replacement. Species richness was significantly reduced along the five N addition levels. Our results revealed a significant relationship between species richness and soil pH, litter amount, soil moisture, AP concentration and inorganic N concentration. Our results indicate that litter accumulation and soil acidification accounted for 52.3% and 43.3% of the variation in species richness, respectively. These findings would advance our knowledge on the changes in species richness in semiarid temperate steppe of northern China under N

Do soil organisms affect aboveground litter decomposition in the semiarid Patagonian steppe, Argentina?

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Araujo, Patricia I; Yahdjian, Laura; Austin, Amy T

2012-01-01

Surface litter decomposition in arid and semiarid ecosystems is often faster than predicted by climatic parameters such as annual precipitation or evapotranspiration, or based on standard indices of litter quality such as lignin or nitrogen concentrations. Abiotic photodegradation has been demonstrated to be an important factor controlling aboveground litter decomposition in aridland ecosystems, but soil fauna, particularly macrofauna such as termites and ants, have also been identified as key players affecting litter mass loss in warm deserts. Our objective was to quantify the importance of soil organisms on surface litter decomposition in the Patagonian steppe in the absence of photodegradative effects, to establish the relative importance of soil organisms on rates of mass loss and nitrogen release. We estimated the relative contribution of soil fauna and microbes to litter decomposition of a dominant grass using litterboxes with variable mesh sizes that excluded groups of soil fauna based on size class (10, 2, and 0.01 mm), which were placed beneath shrub canopies. We also employed chemical repellents (naphthalene and fungicide). The exclusion of macro- and mesofauna had no effect on litter mass loss over 3 years (P = 0.36), as litter decomposition was similar in all soil fauna exclusions and naphthalene-treated litter. In contrast, reduction of fungal activity significantly inhibited litter decomposition (P soil fauna have been mentioned as a key control of litter decomposition in warm deserts, biogeographic legacies and temperature limitation may constrain the importance of these organisms in temperate aridlands, particularly in the southern hemisphere.

Feeding of tropical trees and shrub foliages as a strategy to reduce ruminal methanogenesis: studies conducted in Cuba.

Science.gov (United States)

Delgado, Denia Caridad; Galindo, Juana; González, Rogelio; González, Niurca; Scull, Idania; Dihigo, Luís; Cairo, Juan; Aldama, Ana Irma; Moreira, Onidia

2012-06-01

The aim of this paper was to present the main results obtained in Cuba on the effects of feeding tropical trees and shrubs on rumen methanogenesis in animals fed with low quality fibrous diets. More than 20 tree and shrub foliages were screened for phytochemicals and analyzed for chemical constituents. From these samples, seven promising plants (Samanea saman, Albizia lebbeck, Tithonia diversifolia, Leucaena leucocephala, Trichantera gigantea, Sapindus saponaria, and Morus alba) were evaluated for methane reduction using an in vitro rumen fermentation system. Results indicated that the inclusion levels of 25% of Sapindo, Morus, or Trichantera foliages in the foliages/grass mixtures (grass being Pennisetum purpureum) reduced (P lebbeck, or T. diversifolia accession 23 foliages when mixed at the rate of 30% in Cynodon nlemfuensis grass produced lower methane compared to the grass alone. Inclusion levels of 15% and 25% of a ruminal activator supplement containing 29% of L. leucocehala foliage meal reduced methane by 37% and 42% when compared to the treatment without supplementation. In vivo experiment with sheep showed that inclusion of 27% of L. leucocephala in the diet increased the DM intake but did not show significant difference in methane production compared to control diet without this foliage. The results of these experiments suggest that the feeding of tropical tree and shrub foliages could be an attractive strategy for reduction of ruminal methanogenesis from animals fed with low-quality forage diets and for improving their productivity.

Nonmotorized recreation and motorized recreation in shrub-steppe habitats affects behavior and reproduction of golden eagles (Aquila chrysaetos).

Science.gov (United States)

Spaul, Robert J; Heath, Julie A

2016-11-01

Different forms of outdoor recreation have different spatiotemporal activity patterns that may have interactive or cumulative effects on wildlife through human disturbance, physical habitat change, or both. In western North America, shrub-steppe habitats near urban areas are popular sites for motorized recreation and nonmotorized recreation and can provide important habitat for protected species, including golden eagles. Our objective was to determine whether recreation use (i.e., number of recreationists) or recreation features (e.g., trails or campsites) predicted golden eagle territory occupancy, egg-laying, or the probability a breeding attempt resulted in ≥1 offspring (nest survival). We monitored egg-laying, hatching and fledging success, eagle behavior, and recreation activity within 23 eagle territories near Boise, Idaho, USA. Territories with more off-road vehicle (ORV) use were less likely to be occupied than territories with less ORV use (β = -1.6, 85% CI: -2.8 to -0.8). At occupied territories, early season pedestrian use (β = -1.6, 85% CI: -3.8 to -0.2) and other nonmotorized use (β = -3.6, 85% CI: -10.7 to -0.3) reduced the probability of egg-laying. At territories where eagles laid eggs, short, interval-specific peaks in ORV use were associated with decreased nest survival (β = -0.5, 85% CI: -0.8 to -0.2). Pedestrians, who often arrived near eagle nests via motorized vehicles, were associated with reduced nest attendance (β = -11.9, 85% CI: -19.2 to -4.5), an important predictor of nest survival. Multiple forms of recreation may have cumulative effects on local populations by reducing occupancy at otherwise suitable territories, decreasing breeding attempts, and causing nesting failure. Seasonal no-stopping zones for motorized vehicles may be an alternative to trail closures for managing disturbance. This study demonstrates the importance of considering human disturbance across different parts of the annual cycle, particularly where

Artemisia pollen-indicated steppe distribution in southern China during the Last Glacial Maximum

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Liu Hongyan

2013-07-01

Full Text Available The Last Glacial Maximum (LGM was the coldest period during the previous 20,000 years. There have been different points of views on steppe distribution during the LGM period in southern China, partly due to the different interpretations of Artemisia occurrences. To make a reliable interpretation of the pollen fossil Artemisia, the modern distribution of Artemisia species and the relationship of pollen with climate and vegetation over a large spatial scale in China was thoroughly analyzed. Information about Artemisia species and pollen distributions used in this paper were collected from published works completed by other researchers as well as ourselves. The southern limit of steppe vegetation during the LGM period was interpreted from the published contour map of Artemisia pollen percentages during the LGM. Artemisia species in China are mostly distributed either in the horizontally distributed steppe regions or in the vertically distributed desert-steppe in the desert region, which indicates a cold and dry climate. The steppe is a distribution center of Artemisia pollen. Fractions of Artemisia in surface pollen assemblages are lower in both the desert and the temperate forest. Neither high Artemisia species cover nor high percentages of Artemisia pollen were found in the coast areas of China. Twenty-five percent of Artemisia pollen in sediments might indicate a local occurrence of steppe vegetation. Percentages of Artemisia pollen in the subtropical and tropical forest are less than 10%. A close relationship between Artemisia pollen and temperate steppe in China is demonstrated. The southern edge of the steppe vegetation during the LGM might be along the middle reach of the Yangtze River. Our results support the hypothesis that the isolated high fraction of Artemisia pollen along the northern edge of the South China Sea was transported from a large source area.

Community Structure and Productivity in Western Mongolian Steppe

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Kiyokazu Kawada

2014-12-01

Full Text Available The people of the Mongolian steppe have maintained a sustainable, nomadic lifestyle. However, several ecological processes are threatening their way of life. Ecological changan be detected through the analysis of quantitative and qualitative data. It is therefore, imperative to develop a sustainable rangeland management system aimed at combating desertifi cation. In this study we quantitatively and qualitatively describe several western Mongolian steppe plant communities by examining species composition, plant volume and community structure. Study sites were located in the Uvs and Khovd provinces and had all been affected by livestock grazing. A total of 48 species were found. Stipa krylovii , S . gobica , Cleistogenes songorica , Koeleria cristata and Ajania achilleoides were dominant. There was a signifi cant relationship between biomass and plant volume at all sites. Study sites were classifi ed into four groups using cluster analysis, based on the presence or absence of several species. More than 90% of plant volumes at all groups were perennial grasses and perennial forbs. The ratio of C 3 to C 4 plants at site 3 was reversed in comparison to the other sites. Species highly palatable to livestock were dominant at all sites. To ensure the sustainable use of biological resources in these arid areas, these fi ndings should be taken into account in designing land-use plans.

Competition between a Lawn-Forming Cynodon dactylon and a Tufted Grass Species Hyparrhenia hirta on a South-African Dystrophic Savanna

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Zwerts, J.A.; Prins, H.H.T.; Bomhoff, D.; Verhagen, I.; Swart, J.M.; Boer, de W.F.

2015-01-01

South African savanna grasslands are often characterised by indigestible tufted grass species whereas lawn grasses are far more desirable in terms of herbivore sustenance. We aimed to investigate the role of nutrients and/or the disturbance (grazing, trampling) by herbivores on the formation of

Postfire encroachment of Fabiana imbricata is real? Assessing changes of shrubland occupation during 40 years in NW Patagonia steppe

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Lasaponara, Rosa; Oddi, Facundo; Ghermandi, Luciana

2014-05-01

Landscapes are dynamic in space and time, being spatio-temporal processes of particular interest for landscape ecology. In particular, grasslands can change their structure through the expansion of shrubs in the landscape matrix. Shrub encroachment affect biodiversity as well as forage availability that is the key component of the productive use of rangelands. However, despite its recognition as a global problem, knowledge on the rates, dynamics and encroachment patterns is even scarce. For example, although it is generally accepted that fire control shrub encroachment, certain shrubby species could be favored by the occurrence of fire. In northwestern Patagonian steppe, Fabiana imbricata form large monospecific shrublands that are part of the landscape mosaic and its dynamics of regeneration is strongly related to fire. This long-lived shrub (≡ 150 years) is a typical seeder that is killed by fire and recruits seedlings almost exclusively in post-fire, establishing even-age patches. Our objective was to determine whether F. imbricata shrublands have expanded during the last 40 years in a landscape fire prone. The study area corresponds to San Ramon ranch (22,000 ha) located in northwestern Patagonia steppe, Argentina (latitude -41° 04'; longitude -70° 51'). Two distribution maps of the species were made that corresponds to the study area in 1968 and 2011. The 1968 map was elaborated from the digitalization of aerial photographs (1:45000) while the 2011 map was produced with very high resolution satellite images, current aerial photographs and GPS field data. Both maps were loaded into a GIS environment, in which landscape metrics at patch and class level were determined and then compared. From remote sensing and dendroecological techniques, we know that the study area was almost entirely affected by fires during the study period. Therefore, the comparison of both maps allows us to know post-fire changes in the shrublands spatial configuration at the landscape

The invasive shrub Piper aduncum in Papua New Guinea: a review

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Hartemink, A.E.

2010-01-01

HARTEMINK AE. 2010. The invasive shrub Piper aduneum in Papua New Guinea: a review. Piper aduncum is a shrub native to Central America. It is found in most Central and South American countries and also in the Caribbean and southern Florida (USA). In Asia and the Pacific, P aduncum occurs in

Shrubs as ecosystem engineers across an environmental gradient: effects on species richness and exotic plant invasion.

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Kleinhesselink, Andrew R; Magnoli, Susan M; Cushman, J Hall

2014-08-01

Ecosystem-engineering plants modify the physical environment and can increase species diversity and exotic species invasion. At the individual level, the effects of ecosystem engineers on other plants often become more positive in stressful environments. In this study, we investigated whether the community-level effects of ecosystem engineers also become stronger in more stressful environments. Using comparative and experimental approaches, we assessed the ability of a native shrub (Ericameria ericoides) to act as an ecosystem engineer across a stress gradient in a coastal dune in northern California, USA. We found increased coarse organic matter and lower wind speeds within shrub patches. Growth of a dominant invasive grass (Bromus diandrus) was facilitated both by aboveground shrub biomass and by growing in soil taken from shrub patches. Experimental removal of shrubs negatively affected species most associated with shrubs and positively affected species most often found outside of shrubs. Counter to the stress-gradient hypothesis, the effects of shrubs on the physical environment and individual plant growth did not increase across the established stress gradient at this site. At the community level, shrub patches increased beta diversity, and contained greater rarified richness and exotic plant cover than shrub-free patches. Shrub effects on rarified richness increased with environmental stress, but effects on exotic cover and beta diversity did not. Our study provides evidence for the community-level effects of shrubs as ecosystem engineers in this system, but shows that these effects do not necessarily become stronger in more stressful environments.

Dendrochronological potential of the alpine shrub Rhododendron nivale on the south-eastern Tibetan Plateau.

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Liang, Eryuan; Eckstein, Dieter

2009-09-01

Shrubs and dwarf shrubs are wider spread on the Tibetan Plateau than trees and hence offer a unique opportunity to expand the present dendrochronological network into extreme environments beyond the survival limit of trees. Alpine shrublands on the Tibetan Plateau are characterized by rhododendron species. The dendrochronological potential of one alpine rhododendron species and its growth response to the extreme environment on the south-east Tibetan Plateau were investigated. Twenty stem discs of the alpine snowy rhododendron (Rhododendron nivale) were collected close to the tongue of the Zuoqiupu Glacier in south-east Tibet, China. The skeleton plot technique was used for inter-comparison between samples to detect the growth pattern of each stem section. The ring-width chronology was developed by fitting a negative exponential function or a straight line of any slope. Bootstrapping correlations were calculated between the standard chronology and monthly climate data. The wood of snowy rhododendron is diffuse-porous with evenly distributed small-diameter vessels. It has well-defined growth rings. Most stem sections can be visually and statistically cross-dated. The resulting 75-year-long standard ring-width chronology is highly correlated with a timberline fir chronology about 200 km apart, providing a high degree of confidence in the cross-dating. The climate/growth association of alpine snowy rhododendron and of this timberline fir is similar, reflecting an impact of monthly mean minimum temperatures in November of the previous year and in July during the year of ring formation. The alpine snowy rhododendron offers new research directions to investigate the environmental history of the Tibetan Plateau in those regions where up to now there was no chance of applying dendrochronology.

Soil nitrogen availability in the open steppe with Stipa tenacissima

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Novosadova, Irena; Damian Ruiz Sinoga, Jose; Záhora, Jaroslav

2010-05-01

Open steppes dominated by Stipa tenacissima L. constitute one of the most representative ecosystems of the semi-arid zones of Iberian Peninsula and show a higher degree of variability in composition and structure (Maestre et al., 2007). Vegetation patchiness, which are seen as mosaics including vegetated and non-vegetated components, is a common feature of such open steppes (Valentin et al., 1999). Ecosystem functioning is strongly related to the spatial pattern of grass tussocks. Soils beneath S. tenacissima grass show higher fertility and improved microclimatic conditions, favouring the formation of "resource islands" (Maestre et al., 2007). First, soil moisture is greater beneath the clumps, due to water harvesting through rainfall interception, uptake by roots from adjacent unvegetated areas and water redistribution from gaps to clumps (Bergkamp et al., 1999; Puigdefá bregas et al., 1999). Second, the canopy diminishes the intense solar radiation (Maestre et al., 2001) avoiding the sun-baking effect, which is an important factor for soil temperature change and physical disruption (Magid et al., 1999). Plant clumps either functioned as microbial hotspots where enhanced microbially driven ecosystem processes took place or as microbial banks capable of undergoing a burst of activity under favourable climatic conditions (Goberna et al., 2007). The competition for water and resources between plants and microorganisms is strong and mediated trough an enormous variety of exudates and resource depletion intended to regulate soil microbial communities in the rhizosphere, control herbivory, encourage beneficial symbioses, and change chemical and physical properties in soil (Pugnaire et Armas, 2008). On the other hand there exists experimental evidence of a non-patchy distribution of certain soil microbial properties in semi-arid Mediterranean patchy ecosystems (Goberna et al., 2007). The microbial nutrient release processes have a fundamental role in ecosystem

Nutritional value of cabbage and kikuyu grass as food for grass carp ...

African Journals Online (AJOL)

and digestibility coefficients were obtained for the protein, fibre, ash and fat contents of both ... Cabbage is a superior feed compared to grass for raising grass carp and a suitable low-cost alternative ... Materials and Methods ... from jumping out and was fitted with an air lift under- .... In: Aquatic weeds in South East Asia.

A novel soil manganese mechanism drives plant species loss with increased nitrogen deposition in a temperate steppe.

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Tian, Qiuying; Liu, Nana; Bai, Wenming; Li, Linghao; Chen, Jiquan; Reich, Peter B; Yu, Qiang; Guo, Dali; Smith, Melinda D; Knapp, Alan K; Cheng, Weixin; Lu, Peng; Gao, Yan; Yang, An; Wang, Tianzuo; Li, Xin; Wang, Zhengwen; Ma, Yibing; Han, Xingguo; Zhang, Wen-Hao

2016-01-01

Loss of plant diversity with increased anthropogenic nitrogen (N) deposition in grasslands has occurred globally. In most cases, competitive exclusion driven by preemption of light or space is invoked as a key mechanism. Here, we provide evidence from a 9-yr N-addition experiment for an alternative mechanism: differential sensitivity of forbs and grasses to increased soil manganese (Mn) levels. In Inner Mongolia steppes, increasing the N supply shifted plant community composition from grass-forb codominance (primarily Stipa krylovii and Artemisia frigida, respectively) to exclusive dominance by grass, with associated declines in overall species richness. Reduced abundance of forbs was linked to soil acidification that increased mobilization of soil Mn, with a 10-fold greater accumulation of Mn in forbs than in grasses. The enhanced accumulation of Mn in forbs was correlated with reduced photosynthetic rates and growth, and is consistent with the loss of forb species. Differential accumulation of Mn between forbs and grasses can be linked to fundamental differences between dicots and monocots in the biochemical pathways regulating metal transport. These findings provide a mechanistic explanation for N-induced species loss in temperate grasslands by linking metal mobilization in soil to differential metal acquisition and impacts on key functional groups in these ecosystems.

Spatial and temporal patterns of water availability in a grass-shrub ecotone and implications for grassland recovery in arid environments

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Encroachment of woody shrubs into historic desert grasslands is a major problem throughout the world. Conversion of grasslands to shrub-dominated systems may result in significant alteration of biogeochemical processes and reduced resource availability in shrub interspaces, making grassland recover...

Utility of surface pollen assemblages to delimit Eastern Eurasian steppe types.

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Feng Qin

Full Text Available Modern pollen records have been used to successfully distinguish between specific prairie types in North America. Whether the pollen records can be used to detect the occurrence of Eurasian steppe, or even to further delimit various steppe types was until now unclear. Here we characterized modern pollen assemblages of meadow steppe, typical steppe and desert steppe from eastern Eurasia along an ecological humidity gradient. The multivariate ordination of the pollen data indicated that Eurasian steppe types could be clearly differentiated. The different steppe types could be distinguished primarily by xerophilous elements in the pollen assemblages. Redundancy analysis indicated that the relative abundances of Ephedra, Tamarix, Nitraria and Zygophyllaceae were positively correlated with aridity. The relative abundances of Ephedra increased from meadow steppe to typical steppe and desert steppe. Tamarix and Zygophyllaceae were found in both typical steppe and desert steppe, but not in meadow steppe. Nitraria was only found in desert steppe. The relative abundances of xerophilous elements were greater in desert steppe than in typical steppe. These findings indicate that Eurasian steppe types can be differentiated based on recent pollen rain.

Legume Shrubs Are More Nitrogen-Homeostatic than Non-legume Shrubs.

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Guo, Yanpei; Yang, Xian; Schöb, Christian; Jiang, Youxu; Tang, Zhiyao

2017-01-01

Legumes are characterized as keeping stable nutrient supply under nutrient-limited conditions. However, few studies examined the legumes' stoichiometric advantages over other plants across various taxa in natural ecosystems. We explored differences in nitrogen (N) and phosphorus (P) stoichiometry of different tissue types (leaf, stem, and root) between N 2 -fixing legume shrubs and non-N 2 -fixing shrubs from 299 broadleaved deciduous shrubland sites in northern China. After excluding effects of taxonomy and environmental variables, these two functional groups differed considerably in nutrient regulation. N concentrations and N:P ratios were higher in legume shrubs than in non-N 2 -fixing shrubs. N concentrations were positively correlated between the plants and soil for non-N 2 -fixing shrubs, but not for legume shrubs, indicating a stronger stoichiometric homeostasis in legume shrubs than in non-N 2 -fixing shrubs. N concentrations were positively correlated among three tissue types for non-N 2 -fixing shrubs, but not between leaves and non-leaf tissues for legume shrubs, demonstrating that N concentrations were more dependent among tissues for non-N 2 -fixing shrubs than for legume shrubs. N and P concentrations were correlated within all tissues for both functional groups, but the regression slopes were flatter for legume shrubs than non-N 2 -fixing shrubs, implying that legume shrubs were more P limited than non-N 2 -fixing shrubs. These results address significant differences in stoichiometry between legume shrubs and non-N 2 -fixing shrubs, and indicate the influence of symbiotic nitrogen fixation (SNF) on plant stoichiometry. Overall, N 2 -fixing legume shrubs are higher and more stoichiometrically homeostatic in N concentrations. However, due to excess uptake of N, legumes may suffer from potential P limitation. With their N advantage, legume shrubs could be good nurse plants in restoration sites with degraded soil, but their P supply should be taken care

Competition for soil nitrate and invasive weed resistance of three shrub-steppe growth forms

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Eamonn D. Leonard

2007-01-01

Determining mechanisms responsible for weed resistance and invasion success are two issues that have potential in aiding successful land management decisions. The first experiment evaluates the competitive effects of an invasive annual grass downy brome (Bromus tectorum L.), an invasive biennial forb dyer's woad (Isatis tinctoria...

Strong genetic differentiation in the invasive annual grass Bromus tectorum across the Mojave-Great Basin ecological transition zone

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Susan E. Meyer; Elizabeth A. Leger; Desiree R. Eldon; Craig E. Coleman

2016-01-01

Bromus tectorum, an inbreeding annual grass, is a dominant invader in sagebrush steppe habitat in North America. It is also common in warm and salt deserts, displaying a larger environmental tolerance than most native species. We tested the hypothesis that a suite of habitat-specific B. tectorum lineages dominates warm desert habitats. We sampled 30 B....

Grazing moderates increases in C3 grass abundance over seven decades across a soil texture gradient in shortgrass steppe

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Questions: How does long-term grazing exclusion influence plant community composition in a semiarid grassland? Can spatial variation in the effects of grazing exclusion be explained by variation in soil texture? Location: The shortgrass steppe of northeastern Colorado, USA, located in the North Amer...

When perception reflects reality: Non-native grass invasion alters small mammal risk landscapes and survival

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Ceradnini, Joseph P.; Chalfoun, Anna

2017-01-01

Modification of habitat structure due to invasive plants can alter the risk landscape for wildlife by, for example, changing the quality or availability of refuge habitat. Whether perceived risk corresponds with actual fitness outcomes, however, remains an important open question. We simultaneously measured how habitat changes due to a common invasive grass (cheatgrass, Bromus tectorum) affected the perceived risk, habitat selection, and apparent survival of a small mammal, enabling us to assess how well perceived risk influenced important behaviors and reflected actual risk. We measured perceived risk by nocturnal rodents using a giving-up density foraging experiment with paired shrub (safe) and open (risky) foraging trays in cheatgrass and native habitats. We also evaluated microhabitat selection across a cheatgrass gradient as an additional assay of perceived risk and behavioral responses for deer mice (Peromyscus maniculatus) at two spatial scales of habitat availability. Finally, we used mark-recapture analysis to quantify deer mouse apparent survival across a cheatgrass gradient while accounting for detection probability and other habitat features. In the foraging experiment, shrubs were more important as protective cover in cheatgrass-dominated habitats, suggesting that cheatgrass increased perceived predation risk. Additionally, deer mice avoided cheatgrass and selected shrubs, and marginally avoided native grass, at two spatial scales. Deer mouse apparent survival varied with a cheatgrass–shrub interaction, corresponding with our foraging experiment results, and providing a rare example of a native plant mediating the effects of an invasive plant on wildlife. By synthesizing the results of three individual lines of evidence (foraging behavior, habitat selection, and apparent survival), we provide a rare example of linkage between behavioral responses of animals indicative of perceived predation risk and actual fitness outcomes. Moreover, our results

Phenotypic variability of plant leaves of Acer genus, introduced into steppe zone of Ukraine

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I. O. Zaitseva

2014-10-01

Full Text Available This paper deals with studying of the patterns of ecological adaptation of wood species of Acer L. genus during their introduction into steppe zone of Ukraine. Hydrothermal conditions of the growing season in steppe zone of Ukraine are particularly unfavorable for tree and shrubbery plantings, comprising both native and introduced species. In the course of plants’ introduction, adaptive changes occur; such changes represent the spectrum of phenotypic implementation of the definite genotype under the influence of new environmental conditions. Stress environment of the region of introduction leads to occurrence of a great variety of phenotypic forms, as the different variants of genotype implementation. Studying of phenotypic variability gives an opportunity to determine the capacity to adaptation of introduced species and ways of adaptive reactions in new conditions of living. Therefore, objective of the work consists in studying of the processes of differentiation of morphological characters in species of Acer genus introduced in the regions of steppe zone with varying intensity of hydrothermal factors. Studies were carried out in the central and south-eastern steppe regions, as well as in the south of steppe zone in the coastal and continental areas. Subjects of research were 9 species of maples, differing by their botanic and geographic origin and by the degree of drought resistance in the steppe zone of Ukraine. Patterns of variability of morphostructural characters of leaves were determined by the indicator of specific weight of leaves which was calculated as a ratio of weight of dry laminas to their area (mg/cm2. Following the results of study, it was found that adaptation of maples to xerothermic factors of the environment is connected with changing of the ratio of groups of character variation and their contribution into total sample. Direct relationship is established between the probability density of expression (phenotypic

Ecology of the plant-dwelling spiders (Arachnida: Araneae of the Erfenis Dam Nature Reserve, South Africa

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René Fourie

2013-02-01

Full Text Available As part of the South African National Survey of Arachnida in the Grassland Biome, foliage-dwelling and grass-dwelling spiders (Arachnida: Araneae were collected in the Erfenis Dam Nature Reserve in the central Free State Province from November 2005 to August 2007. Foliage-dwelling spiders were collected from three common tree or shrub species (Acacia karroo, Searsia ciliata and Searsia lancea and grass-dwellers from four contrasting grasslands (uniform Themeda triandra, mixed, weedy and woodland grasslands. From the grass layer, 1649 spiders were collected, representing 15 families and 82 species, whilst 496 tree-dwelling spiders were collected that represented 17 families and 52 species. There was some overlap in the fauna of the two strata, resulting in a total of 108 species from 18 families being collected. The Araneidae, Philodromidae, Salticidae and Thomisidae were consistently the most abundant in all grassland types and tree species, although Salticidae were scarce on A. karroo. Assemblage analysis indicates high similarity and overlap in the fauna of the four grassland types, suggesting that the structural complexity of grasslands has a limited effect on species composition. In contrast, the foliage-dwelling assemblages were more distinct, with only some overlap between the faunas of S. ciliata and A. karroo, suggesting a stronger vegetation structural effect in shaping arboreal spider assemblages. The isolation of trees and shrubs within the extensive grassy habitat may contribute to the more unique fauna and lower species richness of the woody vegetation. Conservation implications: This study uncovered a rich diversity of plant-dwelling spiders from central South Africa. Grassland faunas show considerable temporal variation and some variability in microhabitat preferences, and sampling protocols should take this into account when spiders are considered in management plans and biodiversity surveys in reserves and private land.

Ecology of the plant-dwelling spiders (Arachnida: Araneae of the Erfenis Dam Nature Reserve, South Africa

Directory of Open Access Journals (Sweden)

René Fourie

2013-04-01

Full Text Available As part of the South African National Survey of Arachnida in the Grassland Biome, foliage-dwelling and grass-dwelling spiders (Arachnida: Araneae were collected in the Erfenis Dam Nature Reserve in the central Free State Province from November 2005 to August 2007. Foliage-dwelling spiders were collected from three common tree or shrub species (Acacia karroo, Searsia ciliata and Searsia lancea and grass-dwellers from four contrasting grasslands (uniform Themeda triandra, mixed, weedy and woodland grasslands. From the grass layer, 1649 spiders were collected, representing 15 families and 82 species, whilst 496 tree-dwelling spiders were collected that represented 17 families and 52 species. There was some overlap in the fauna of the two strata, resulting in a total of 108 species from 18 families being collected. The Araneidae, Philodromidae, Salticidae and Thomisidae were consistently the most abundant in all grassland types and tree species, although Salticidae were scarce on A. karroo. Assemblage analysis indicates high similarity and overlap in the fauna of the four grassland types, suggesting that the structural complexity of grasslands has a limited effect on species composition. In contrast, the foliage-dwelling assemblages were more distinct, with only some overlap between the faunas of S. ciliata and A. karroo, suggesting a stronger vegetation structural effect in shaping arboreal spider assemblages. The isolation of trees and shrubs within the extensive grassy habitat may contribute to the more unique fauna and lower species richness of the woody vegetation. Conservation implications: This study uncovered a rich diversity of plant-dwelling spiders from central South Africa. Grassland faunas show considerable temporal variation and some variability in microhabitat preferences, and sampling protocols should take this into account when spiders are considered in management plans and biodiversity surveys in reserves and private land.

Dwarf shrub and grass vegetation resistant to long-term experimental warming while microarthropod abundance declines on the Falkland Islands

NARCIS (Netherlands)

Bokhorst, S.; Convey, P.; Huiskes, A.; Aerts, R.; Huiskes, A.

2017-01-01

Dwarf shrubs are a dominant plant type across many regions of the Earth and have hence a large impact on carbon and nutrient cycling rates. Climate change impacts on dwarf shrubs have been extensively studied in the Northern Hemisphere, and there appears to be large variability in response between

Water relations and photosynthetic performance in Larix sibirica growing in the forest-steppe ecotone of northern Mongolia.

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Dulamsuren, Choimaa; Hauck, Markus; Bader, Martin; Osokhjargal, Dalaikhuu; Oyungerel, Shagjjav; Nyambayar, Suran; Runge, Michael; Leuschner, Christoph

2009-01-01

region. Higher stomatal conductance concomitant to lower Psi(m) in trees of northern-slope forests compared to trees from the forest line to the steppe may be the result of a recent increase in drought intensity that affects better drought-adapted trees at the forest edge less than the trees in the forest interior. We conclude that drought is a key factor explaining the forest-steppe borderline in northern Mongolia. The proportion of forests within the present vegetation pattern of forests on north-facing slopes and the grasslands on south-facing slopes in Mongolia's forest-steppe ecotone is not likely to increase under the present climate, but may decrease with increasing aridity due to global warming.

Carbon balance assessment of a natural steppe of southern Siberia by multiple constraint approach

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L. Belelli Marchesini

2007-08-01

Full Text Available Steppe ecosystems represent an interesting case in which the assessment of carbon balance may be performed through a cross validation of the eddy covariance measurements against ecological inventory estimates of carbon exchanges (Ehman et al., 2002; Curtis et al., 2002.

Indeed, the widespread presence of ideal conditions for the applicability of the eddy covariance technique, as vast and homogeneous grass vegetation cover over flat terrains (Baldocchi, 2003, make steppes a suitable ground to ensure a constrain to flux estimates with independent methodological approaches.

We report about the analysis of the carbon cycle of a true steppe ecosystem in southern Siberia during the growing season of 2004 in the framework of the TCOS-Siberia project activities performed by continuous monitoring of CO₂ fluxes at ecosystem scale by the eddy covariance method, fortnightly samplings of phytomass, and ingrowth cores extractions for NPP assessment, and weekly measurements of heterotrophic component of soil CO₂ effluxes obtained by an experiment of root exclusion.

The carbon balance of the monitored natural steppe was, according to micrometeorological measurements, a sink of carbon of 151.7±36.9 g C m⁻², cumulated during the growing season from May to September. This result was in agreement with the independent estimate through ecological inventory which yielded a sink of 150.1 g C m⁻² although this method was characterized by a large uncertainty (±130% considering the 95% confidence interval of the estimate. Uncertainties in belowground process estimates account for a large part of the error. Thus, in particular efforts to better quantify the dynamics of root biomass (growth and turnover have to be undertaken in order to reduce the uncertainties in the assessment of NPP. This assessment should be preferably based on the application of multiple methods, each one characterized by its

Response of gross ecosystem productivity, light use efficiency, and water use efficiency of Mongolian steppe to seasonal variations in soil moisture

Science.gov (United States)

Li, Sheng-Gong; Eugster, Werner; Asanuma, Jun; Kotani, Ayumi; Davaa, Gombo; Oyunbaatar, Dambaravjaa; Sugita, Michiaki

2008-03-01

The examination of vegetation productivity and use of light and water resources is important for understanding the carbon and water cycles in semiarid and arid environments. We made continuous measurements of carbon dioxide and water vapor fluxes over an arid steppe ecosystem in Mongolia by using the eddy covariance (EC) technique. These measurements allow an examination of EC-estimated gross ecosystem productivity (GEP), light use efficiency (LUE), and water use efficiency (WUE) of the steppe. Daily variations of GEP, LUE, and WUE were associated with daily variations of incident photosynthetically active radiation (PAR), ambient temperature (Ta), and vapor pressure deficit (VPD). The magnitudes of these variations were also dependent on canopy development. On the daily basis, GEP linearly correlated with evapotranspiration rate and PAR. LUE correlated positively with leaf area index, Ta, and soil moisture availability but negatively with the surface reflectivity for short-wave solar radiation. Throughout the growing season, both GEP and LUE responded strongly to precipitation-fed soil moisture in the top 20 cm of the soil. An examination of the responses of LUE and WUE to PAR under different soil moisture conditions shows that when soil water availability exceeded VPD, the steppe was most efficient in light use, whereas it was less efficient in water use. The multivariate analysis of variance also suggests that soil moisture availability, especially water status in the upper 20-cm soil layer with dense distribution of grass roots, is the most significant factor that governs GEP, WUE, and LUE. This study provides a preliminary assessment of the use of available water and light by the Mongolian arid steppe ecosystems under seasonally varying soil moisture conditions. A better understanding of these functional responses is required to predict how climate change may affect arid steppe ecosystems.

U.S. Geological Survey shrub/grass products provide new approach to shrubland monitoring

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Young, Steven M.

2017-12-11

In the Western United States, shrubland ecosystems provide vital ecological, hydrological, biological, agricultural, and recreational services. However, disturbances such as livestock grazing, exotic species invasion, conversion to agriculture, climate change, urban expansion, and energy development are altering these ecosystems.Improving our understanding of how shrublands are distributed, where they are changing, the extent of the historical change, and likely future change directions is critical for successful management of these ecosystems. Remote-sensing technologies provide the most likely data source for large-area monitoring of ecosystem disturbance—both near-real time and historically. A monitoring framework supported by remote-sensing data can offer efficient and accurate analysis of change across a range of spatial and temporal scales.The U.S. Geological Survey has been working to develop new remote-sensing data, tools, and products to characterize and monitor these changing shrubland landscapes. Nine individual map products (components) have been developed that quantify the percent of shrub, sagebrush, big sagebrush, herbaceous, annual herbaceous, litter, bare ground, shrub height, and sagebrush height at 1-percent intervals in each 30-meter grid cell. These component products are designed to be combined and customized to widely support different applications in rangeland monitoring, analysis of wildlife habitat, resource inventory, adaptive management, and environmental review.

Linking snake habitat use to nest predation risk in grassland birds: the dangers of shrub cover.

Science.gov (United States)

Klug, Page E; Jackrel, Sara L; With, Kimberly A

2010-03-01

Extremes in rangeland management, varying from too-frequent fire and intensive grazing to the suppression of both, threaten rangeland ecosystems worldwide. Intensive fire and grazing denude and homogenize vegetation whereas their suppression increases woody cover. Although habitat loss is implicated in grassland bird declines, degradation through intensive management or neglect also decreases breeding habitat and may reduce nesting success through increased rates of nest predation. Snakes are important nest predators, but little is known about how habitat use in snakes relates to predation risk for grassland birds nesting within tallgrass prairie subjected to different grazing and fire frequencies. We evaluated nest survival in the context of habitat used by nesting songbirds and two bird-eating snakes, the eastern yellowbelly racer Coluber constrictor flaviventris and Great Plains ratsnake Pantherophis emoryi. Daily nest survival rates decreased with increasing shrub cover and decreasing vegetation height, which characterize grasslands that have been neglected or intensively managed, respectively. Discriminant function analysis revealed that snake habitats were characterized by higher shrub cover, whereas successful nests were more likely to occur in areas with tall grass and forbs but reduced shrub cover. Because snakes often use shrub habitat, birds nesting in areas with increased shrub cover may be at higher risk of nest predation by snakes in addition to other predators known to use shrub habitat (e.g., mid-sized carnivores and avian predators). Depredated nests also occurred outside the discriminant space of the snakes, indicating that other predators (e.g., ground squirrels Spermophilus spp. and bullsnakes Pituophis catenifer) may be important in areas with denuded cover. Targeted removal of shrubs may increase nest success by minimizing the activity of nest predators attracted to shrub cover.

Fate of leaf-litter N in forest and grassland along a pedo-climatic gradient in south-western Siberia: an in situ 15N-labelling experiment

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Brédoire, Félix; Zeller, Bernd; Nikitich, Polina; Barsukov, Pavel A.; Rusalimova, Olga; Bakker, Mark R.; Legout, Arnaud; Bashuk, Alexander; Kayler, Zachary E.; Derrien, Delphine

2017-04-01

The suitability of Siberia for agriculture is expected to increase in the next decades due to strong and rapid climatic changes, but little is known on the environmental drivers of soil fertility there, especially nitrogen (N). Plant-available N is mainly derived from litter decomposition. South-western (SW) Siberia is located on the transition between several bioclimatic zones that are predicted to shift and extend along with climate change (steppe, forest-steppe, sub-taiga). The soils of this region are formed on a common loess deposit but they are submitted to different climatic conditions and vegetation cover. In the south of the region, typically in steppe/forest-steppe, soil freezes over winter because of a relatively shallow snow-pack, and water shortages are frequent in summer. In the north, typically in sub-taiga, the soil is barely frozen in winter due to a thick snow-pack and sufficient soil moisture in summer. In this study, we characterized the dynamics of leaf litter decomposition and the transfer of N from leaf litter to the soil and back to plants. Four sites were chosen along a climate gradient (temperature, precipitation and snow depth). At each site, we applied 15N-labelled leaf litter on the soil surface in experimental plots in an aspen (Populus tremula L.) forest and in a grassland. Twice a year during three years, we tracked the 15N derived from the decomposing labelled-litter in the organic layers, in the first 15 cm of the soil, and in above-ground vegetation. Soil temperature and moisture were monitored at a daily timestep over three years and soil water budgets were simulated (BILJOU model, Granier et al. 1999). We observed contrasting patterns in the fate of litter-derived 15N between bioclimatic zones. Over three years, along with faster decay rates, the release of leaf litter-N was faster in sub-taiga than in forest-steppe. As such, higher quantities of 15N were transferred into the soil in sub-taiga. The transfer was also deeper there

Flora and fauna associated with prairie dog colonies and adjacent ungrazed mixed-grass prairie in western South Dakota

Science.gov (United States)

William Agnew; Daniel W. Uresk; Richard M. Hansen

1986-01-01

Vegetation, small rodents, and birds were sampled during the growing seasons of 2 years on prairie dog (Cynomys ludovicianus) colonies and adjacent mixed-grass prairie in western South Dakota. Prairie dog grazing decreased mulch cover, maximum height of vegetation, plant species richness, and tended to decrease live plant canopy cover compared to...

SPATIAL AND TEMPORAL VARIABILITY OF DRY STEPPES OF EASTERN MONGOLIA

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Galina Ogureeva

2011-01-01

Full Text Available Spatial-temporal structure and coenotic diversity of dry steppes of Eastern Mongolia was identified by analyzing characteristics of naturally occurring vegetation connection to the regional landscape structure. Different types of combinations of plant communities (phytocoenochores were determined in the vegetation structure of the Eastern Steppe Station Tumén-Tsogt (in Sukhebator district. Temporal dynamics of steppe ecosystems was defined from the studies of steppe cover fluctuations in 2008. The coenotic role of eight annual plant species that form synusiae in the steppe communities was shown through analysis of species constancy, projective cover, and activity. Knowledge about the trend of successions and the manifestation of fluctuations in vegetation cover is necessary for the development of science-based system of management options to maintain the number and abundance of different plant groups in plant communities. Monitoring the state of natural ecosystems has a major scientific and practical importance, since steppe ecosystems are the basic component of the pasture’s resources of the country.

Pruning Shrubs

OpenAIRE

French, Sue (Sue C.); Appleton, Bonnie Lee, 1948-2012

2009-01-01

Understanding the "natural habit" or "shape" of shrubs will help you determine how to prune them. This publication explores how and when to prune, maintenance and rejuvenation pruning, and the growth habit of shrubs.

Effects of Plant Functional Group Loss on Soil Microbial Community and Litter Decomposition in a Steppe Vegetation.

Science.gov (United States)

Xiao, Chunwang; Zhou, Yong; Su, Jiaqi; Yang, Fan

2017-01-01

Globally, many terrestrial ecosystems are experiencing a rapid loss of biodiversity. Continued improvements in our understanding of interrelationships between plant diversity and soil microbes are critical to address the concern over the consequences of the decline in biodiversity on ecosystem functioning and services. By removing forbs, or grasses, or, to an extreme scenario, both forbs and grasses in a steppe vegetation in Inner Mongolia, we studied how plant functional group (PFG) loss affects soil microbial community composition using phospholipid fatty acid analysis (PLFA) and litter decomposition using a litter-bag method. PFG loss significantly decreased above- and below-ground plant biomass, soil microbial biomass carbon (SMBC) and nitrogen (SMBN), but had no effect on the ratio of SMBC to SMBN. Although the ratio of fungal to bacterial PLFAs remained unaffected, PFG loss significantly reduced the amount of bacterial, fungal, and total PLFAs. PFG loss decreased litter monthly mass loss and decay constant, and such decrease was significant when both forbs and grasses were removed. Our results provide robust evidence that PFG loss in grassland ecosystem can lead to a rapid response of soil microbial activity which may affect litter decomposition and soil nutrient cycling, suggesting that the assessment of plant-microbe interactions in soils is an integral component of ecosystem response to biodiversity loss.

Steppe Eagle in the Karaganda Region, Kazakhstan

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Igor V. Karyakin

2018-03-01

Full Text Available Between June 22 and July 18, 2017, fieldworks were carried out to study the population structure and demographic characteristics of the Steppe Eagle breeding groups (Aquila nipalensis in the central part of the Karaganda region of Kazakhstan. In the course of the work 808 birds we found, 280 Steppe Eagle breeding territories were localized. Within 10 registration areas 277 Steppe Eagle breeding territories (96.18 % were examined, including 70 successful nests with 102 nestlings. The occupation of breeding territories was 87.73 %, while the percentage of active nests in the occupied breeding territories was 69.14 %. Successful were 42.26 % of nests from the number of active nests and 25.63 % from the number of identified breeding territories. The number of nestlings in broods ranged from 1 to 3, averaging (n=71 1.45±0.56 nestlings per successful nest and (n=168 0.61±0.80 nestlings per occupied nest. With a very high percentage of nests with unsuccessful breeding (54.46 % of the number of active ones, high percentage of nests with dead clutch was recorded – 34.55 % of the number of nests with unsuccessful breeding. Distribution density of Steppe Eagle active nests averaged 7.67/100 km2, varying in different areas from 4.11 to 12.90/100 km2. The distribution density of Steppe Eagle successful nests on the areas varied from 0 to 4.81/100 km2 averaged 3.24/100 km2. For the area of habitats suitable for breeding across the Karaganda region (142,549.9 km2, the abundance of the Steppe Eagle in nesting was 4,794–5,814, at average 5,275 pairs and 2,183–2,647, at average 2,402 successful pairs.

Ecosystem responses to warming and watering in typical and desert steppes

Science.gov (United States)

Xu, Zhenzhu; Hou, Yanhui; Zhang, Lihua; Liu, Tao; Zhou, Guangsheng

2016-10-01

Global warming is projected to continue, leading to intense fluctuations in precipitation and heat waves and thereby affecting the productivity and the relevant biological processes of grassland ecosystems. Here, we determined the functional responses to warming and altered precipitation in both typical and desert steppes. The results showed that watering markedly increased the aboveground net primary productivity (ANPP) in a typical steppe during a drier year and in a desert steppe over two years, whereas warming manipulation had no significant effect. The soil microbial biomass carbon (MBC) and the soil respiration (SR) were increased by watering in both steppes, but the SR was significantly decreased by warming in the desert steppe only. The inorganic nitrogen components varied irregularly, with generally lower levels in the desert steppe. The belowground traits of soil total organic carbon (TOC) and the MBC were more closely associated with the ANPP in the desert than in the typical steppes. The results showed that the desert steppe with lower productivity may respond strongly to precipitation changes, particularly with warming, highlighting the positive effect of adding water with warming. Our study implies that the habitat- and year-specific responses to warming and watering should be considered when predicting an ecosystem’s functional responses under climate change scenarios.

The phytosociology of the southern section of Borakalalo Nature Reserve, South Africa

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L.R. Brown

1994-08-01

Full Text Available As part of a vegetation survey programme for conservation areas in South Africa, the plant communities of the Borakalalo Nature Reserve were investigated. A TWINSPAN classification, refined by Braun-Blanquet procedures was used for a phytosociological study. The analysis resulted in five major plant communities, one with two subcommunities and one with four subcommunities and two variants. Habitat factors associated with differences in vegetation include topography, soil form and grazing pressure. Descriptions of the plant communities include diagnostic species as well as prominent and less conspicuous species of the tree, shrub, forb and grass strata. The classification provides the necessary delimitation of homogeneous areas which are considered necessary for veld management.

Resource-use efficiencies of three indigenous tree species planted in resource islands created by shrubs: implications for reforestation of subtropical degraded shrublands

Science.gov (United States)

Nan Liu; Qinfeng Guo

2012-01-01

Shrub resource islands are characterized by resources accumulated shrubby areas surrounded by relative barren soils. This research aims to determine resource-use efficiency of native trees species planted on shrub resource islands, and to determine how the planted trees may influence the resource islands in degraded shrublands in South China. Shrub (Rhodomyrtus...

A synopsis of short-term response to alternative restoration treatments in sagebrush-steppe: the SageSTEP project

Science.gov (United States)

McIver, James; Brunson, Mark; Bunting, Steve; Chambers, Jeanne; Doescher, Paul; Grace, James; Hulet, April; Johnson, Dale; Knick, Steven T.; Miller, Richard; Pellant, Mike; Pierson, Fred; Pyke, David; Rau, Benjamin; Rollins, Kim; Roundy, Bruce; Schupp, Eugene; Tausch, Robin; Williams, Jason

2014-01-01

The Sagebrush Steppe Treatment Evaluation Project (SageSTEP) is an integrated long-term study that evaluates ecological effects of alternative treatments designed to reduce woody fuels and to stimulate the herbaceous understory of sagebrush steppe communities of the Intermountain West. This synopsis summarizes results through 3 yr posttreatment. Woody vegetation reduction by prescribed fire, mechanical treatments, or herbicides initiated a cascade of effects, beginning with increased availability of nitrogen and soil water, followed by increased growth of herbaceous vegetation. Response of butterflies and magnitudes of runoff and erosion closely followed herbaceous vegetation recovery. Effects on shrubs, biological soil crust, tree cover, surface woody fuel loads, and sagebrush-obligate bird communities will take longer to be fully expressed. In the short term, cool wet sites were more resilient than warm dry sites, and resistance was mostly dependent on pretreatment herbaceous cover. At least 10 yr of posttreatment time will likely be necessary to determine outcomes for most sites. Mechanical treatments did not serve as surrogates for prescribed fire in how each influenced the fuel bed, the soil, erosion, and sage-obligate bird communities. Woody vegetation reduction by any means resulted in increased availability of soil water, higher herbaceous cover, and greater butterfly numbers. We identified several trade-offs (desirable outcomes for some variables, undesirable for others), involving most components of the study system. Trade-offs are inevitable when managing complex natural systems, and they underline the importance of asking questions about the whole system when developing management objectives. Substantial spatial and temporal heterogeneity in sagebrush steppe ecosystems emphasizes the point that there will rarely be a “recipe” for choosing management actions on any specific area. Use of a consistent evaluation process linked to monitoring may be the

DEER BELIEF AND DEER SACRIFICE AROUND STEPPE CULTURE

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Aslı KAHRAMAN ÇINAR

2016-04-01

Full Text Available Turkish people have spreaded on a large area historically. They have left a mark on all the places they reach. The history of Turks begun in Central Asian Steppes. In reaction to the steppe culture, the human communities of Turks are hunter-nomad communities. The hunter-nomad comminuties make a living from stockfarming and apiculture. The deer is one of the essential animals for t he hunter-nomad communities in the daily life. In the steppe, the deer is seen in all area of social life. Further, the deer motives are commonly used in political, military, financial, the most religious areas. The hunter-nomad comminuties benefit by the meat, milk, leather, horns, nails, etc of the deer. In this study, we dwell on the deer with regard to its intended purposes and usage areas according to steppe culture. The references of this study are references are inscriptions, mythologic stories and archeological datas.

Sparrow nest survival in relation to prescribed fire and woody plant invasion in a northern mixed-grass prairie

Science.gov (United States)

Murphy, Robert K.; Shaffer, Terry L.; Grant, Todd A.; Derrig, James L.; Rubin, Cory S.; Kerns, Courtney K.

2017-01-01

Prescribed fire is used to reverse invasion by woody vegetation on grasslands, but managers often are uncertain whether influences of shrub and tree reduction outweigh potential effects of fire on nest survival of grassland birds. During the 2001–2003 breeding seasons, we examined relationships of prescribed fire and woody vegetation to nest survival of clay-colored sparrow (Spizella pallida) and Savannah sparrow (Passerculus sandwichensis) in mixed-grass prairie at Des Lacs National Wildlife Refuge in northwestern North Dakota, USA. We assessed relationships of nest survival to 1) recent fire history, in terms of number of breeding seasons (2, 3, or 4–5) since the last prescribed fire, and 2) prevalence of trees and tall (>1.5 m) shrubs in the landscape and of low (≤1.5 m) shrubs within 5 m of nests. Nest survival of both species exhibited distinct patterns related to age of the nest and day of year, but bore no relationship to fire history. Survival of clay-colored sparrow nests declined as the amount of trees and tall shrubs within 100 m increased, but we found no relationship to suggest nest parasitism by brown-headed cowbirds (Molothrus ater) as an underlying mechanism. We found little evidence linking nest survival of Savannah sparrow to woody vegetation. Our results suggest that fire can be used to restore northern mixed-grass prairies without adversely affecting nest survival of ≥2 widespread passerine species. Survival of nests of clay-colored sparrow may increase when tall woody cover is reduced by fire. Our data lend support to the use of fire for reducing scattered patches of tall woody cover to enhance survival of nests of ≥1 grassland bird species in northern mixed-grass prairies, but further study is needed that incorporates experimental approaches and assessments of shorter term effects of fire on survival of nests of grassland passerines.

137 ancient human genomes from across the Eurasian steppes.

Science.gov (United States)

Damgaard, Peter de Barros; Marchi, Nina; Rasmussen, Simon; Peyrot, Michaël; Renaud, Gabriel; Korneliussen, Thorfinn; Moreno-Mayar, J Víctor; Pedersen, Mikkel Winther; Goldberg, Amy; Usmanova, Emma; Baimukhanov, Nurbol; Loman, Valeriy; Hedeager, Lotte; Pedersen, Anders Gorm; Nielsen, Kasper; Afanasiev, Gennady; Akmatov, Kunbolot; Aldashev, Almaz; Alpaslan, Ashyk; Baimbetov, Gabit; Bazaliiskii, Vladimir I; Beisenov, Arman; Boldbaatar, Bazartseren; Boldgiv, Bazartseren; Dorzhu, Choduraa; Ellingvag, Sturla; Erdenebaatar, Diimaajav; Dajani, Rana; Dmitriev, Evgeniy; Evdokimov, Valeriy; Frei, Karin M; Gromov, Andrey; Goryachev, Alexander; Hakonarson, Hakon; Hegay, Tatyana; Khachatryan, Zaruhi; Khaskhanov, Ruslan; Kitov, Egor; Kolbina, Alina; Kubatbek, Tabaldiev; Kukushkin, Alexey; Kukushkin, Igor; Lau, Nina; Margaryan, Ashot; Merkyte, Inga; Mertz, Ilya V; Mertz, Viktor K; Mijiddorj, Enkhbayar; Moiyesev, Vyacheslav; Mukhtarova, Gulmira; Nurmukhanbetov, Bekmukhanbet; Orozbekova, Z; Panyushkina, Irina; Pieta, Karol; Smrčka, Václav; Shevnina, Irina; Logvin, Andrey; Sjögren, Karl-Göran; Štolcová, Tereza; Tashbaeva, Kadicha; Tkachev, Alexander; Tulegenov, Turaly; Voyakin, Dmitriy; Yepiskoposyan, Levon; Undrakhbold, Sainbileg; Varfolomeev, Victor; Weber, Andrzej; Kradin, Nikolay; Allentoft, Morten E; Orlando, Ludovic; Nielsen, Rasmus; Sikora, Martin; Heyer, Evelyne; Kristiansen, Kristian; Willerslev, Eske

2018-05-09

For thousands of years the Eurasian steppes have been a centre of human migrations and cultural change. Here we sequence the genomes of 137 ancient humans (about 1× average coverage), covering a period of 4,000 years, to understand the population history of the Eurasian steppes after the Bronze Age migrations. We find that the genetics of the Scythian groups that dominated the Eurasian steppes throughout the Iron Age were highly structured, with diverse origins comprising Late Bronze Age herders, European farmers and southern Siberian hunter-gatherers. Later, Scythians admixed with the eastern steppe nomads who formed the Xiongnu confederations, and moved westward in about the second or third century BC, forming the Hun traditions in the fourth-fifth century AD, and carrying with them plague that was basal to the Justinian plague. These nomads were further admixed with East Asian groups during several short-term khanates in the Medieval period. These historical events transformed the Eurasian steppes from being inhabited by Indo-European speakers of largely West Eurasian ancestry to the mostly Turkic-speaking groups of the present day, who are primarily of East Asian ancestry.

Malheur River Wildlife Mitigation Project : 2008 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Kesling, Jason; Abel, Chad; Schwabe, Laurence

2009-01-01

In 1998, the Burns Paiute Tribe (BPT) submitted a proposal to Bonneville Power Administration (BPA) for the acquisition of the Malheur River Wildlife Mitigation Project (Project). The proposed mitigation site was for the Denny Jones Ranch and included Bureau of Land Management (BLM) and Oregon Division of State Lands (DSL) leases and grazing allotments. The Project approval process and acquisition negotiations continued for several years until the BPT and BPA entered into a Memorandum of Agreement, which allowed for purchase of the Project in November 2000. The 31,781 acre Project is located seven miles east of Juntura, Oregon and is adjacent to the Malheur River (Figure 1). Six thousand three hundred eighty-five acres are deeded to BPT, 4,154 acres are leased from DSL, and 21,242 acres are leased from BLM (Figure 2). In total 11 grazing allotments are leased between the two agencies. Deeded land stretches for seven miles along the Malheur River. It is the largest private landholding on the river between Riverside and Harper, Oregon. Approximately 938 acres of senior water rights are included with the Ranch. The Project is comprised of meadow, wetland, riparian and shrub-steppe habitats. The BLM grazing allotment, located south of the ranch, is largely shrub-steppe habitat punctuated by springs and seeps. Hunter Creek, a perennial stream, flows through both private and BLM lands. Similarly, the DSL grazing allotment, which lies north of the Ranch, is predominantly shrub/juniper steppe habitat with springs and seeps dispersed throughout the upper end of draws (Figure 2).

Measuring carbon in shrubs. Chapter 5

Science.gov (United States)

David C. Chojnacky; Mikaila Milton

2008-01-01

Although shrubs are a small component of the overall carbon budget, shrub lands and shrub cover within forested lands warrant monitoring with consistent procedures to account for carbon in shrubs and to track carbon accumulation as communities change from shrubs to trees and vice versa. Many different procedures have been used to sample and measure shrubs (Bonham 1989...

The CO2 exchange of biological soil crusts in a semiarid grass-shrubland at the northern transition zone of the Negev desert, Israel

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M. O. Andreae

2008-10-01

Full Text Available Biological soil crusts (BSC contribute significantly to the soil surface cover in many dryland ecosystems. A mixed type of BSC, which consists of cyanobacteria, mosses and cyanolichens, constitutes more than 60% of ground cover in the semiarid grass-shrub steppe at Sayeret Shaked in the northern Negev Desert, Israel. This study aimed at parameterizing the carbon sink capacity of well-developed BSC in undisturbed steppe systems. Mobile enclosures on permanent soil borne collars were used to investigate BSC-related CO2 fluxes in situ and with natural moisture supply during 10 two-day field campaigns within seven months from fall 2001 to summer 2002. Highest BSC-related CO2 deposition between –11.31 and –17.56 mmol m−2 per 15 h was found with BSC activated from rain and dew during the peak of the winter rain season. Net CO2 deposition by BSC was calculated to compensate 120%, –26%, and less than 3% of the concurrent soil CO2 efflux from November–January, February–May and November–May, respectively. Thus, BSC effectively compensated soil CO2 effluxes when CO2 uptake by vascular vegetation was probably at its low point. Nighttime respiratory emission reduced daily BSC-related CO2 deposition within the period November–January by 11–123% and on average by 27%. The analysis of CO2 fluxes and water inputs from the various sources showed that the bulk of BSC-related CO2 deposition occurs during periods with frequent rain events and subsequent condensation from water accumulated in the upper soil layers. Significant BSC activity on days without detectable atmospheric water supply emphasized the importance of high soil moisture contents as additional water source for soil-dwelling BSC, whereas activity upon dew formation at low soil water contents was not of major importance for BSC-related CO2 deposition. However, dew may still be important in attaining a pre-activated status during the transition from a long "summer" anabiosis towards

Improving Rangeland Monitoring and Assessment: Integrating Remote Sensing, GIS, and Unmanned Aerial Vehicle Systems

Energy Technology Data Exchange (ETDEWEB)

Robert Paul Breckenridge

2007-05-01

Creeping environmental changes are impacting some of the largest remaining intact parcels of sagebrush steppe ecosystems in the western United States, creating major problems for land managers. The Idaho National Laboratory (INL), located in southeastern Idaho, is part of the sagebrush steppe ecosystem, one of the largest ecosystems on the continent. Scientists at the INL and the University of Idaho have integrated existing field and remotely sensed data with geographic information systems technology to analyze how recent fires on the INL have influenced the current distribution of terrestrial vegetation. Three vegetation mapping and classification systems were used to evaluate the changes in vegetation caused by fires between 1994 and 2003. Approximately 24% of the sagebrush steppe community on the INL was altered by fire, mostly over a 5-year period. There were notable differences between methods, especially for juniper woodland and grasslands. The Anderson system (Anderson et al. 1996) was superior for representing the landscape because it includes playa/bare ground/disturbed area and sagebrush steppe on lava as vegetation categories. This study found that assessing existing data sets is useful for quantifying fire impacts and should be helpful in future fire and land use planning. The evaluation identified that data from remote sensing technologies is not currently of sufficient quality to assess the percentage of cover. To fill this need, an approach was designed using both helicopter and fixed wing unmanned aerial vehicles (UAVs) and image processing software to evaluate six cover types on field plots located on the INL. The helicopter UAV provided the best system compared against field sampling, but is more dangerous and has spatial coverage limitations. It was reasonably accurate for dead shrubs and was very good in assessing percentage of bare ground, litter and grasses; accuracy for litter and shrubs is questionable. The fixed wing system proved to be

Biotic constraints on the establishment and performance of native, naturalized, and invasive plants in Pacific Northwest (USA steppe and forest

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Brian M. Connolly

2017-02-01

Full Text Available Factors that cause differential establishment among naturalized, invasive, and native species are inadequately documented, much less often quantified among different communities. We evaluated the effects of seed addition and disturbance (i.e., understory canopy removal on the establishment and seedling biomass among two naturalized, two invasive, and two native species (1 forb, 1 grass in each group within steppe and low elevation forest communities in eastern Washington, USA. Establishment within each plant immigrant class was enhanced by seed addition: naturalized species showed the greatest difference in establishment between seed addition and no seed addition plots, native and invasive species establishment also increased following seed addition but not to the same magnitude as naturalized species. Within seed addition plots, understory canopy disturbance resulted in significant increases in plant establishment (regardless of plant immigration class relative to undisturbed plots and the magnitude of this effect was comparable between steppe and adjacent forest. However, regardless of disturbance treatment fewer invasive plants established in the forest than in the steppe, whereas native and naturalized plant establishment did not differ between the habitats. Individual biomass of naturalized species were consistently greater in disturbed (canopy removed versus undisturbed control plots and naturalized species were also larger in the steppe than in the forest at the time of harvest. Similar trends in plant size were observed for the native and invasive species, but the differences in biomass for these two immigration classes between disturbance treatments and between habitats were not significant. We found that strong limitations of non-native species is correlated with intact canopy cover within the forest understory, likely driven by the direct or indirect consequences of low light transmittance through the arboreal and understory canopy

Basic chromosome numbers and polyploid levels in some South African and Australian grasses (Poaceae

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J. J. Spies

1991-10-01

Full Text Available Chromosome numbers of 46 specimens of grasses, involving 24 taxa from South Africa and Australia, have been determined during the present study. For the first time chromosome numbers are given for Eragrostis sarmentosa (Thunb. Trin. (n = 20. Panicum aequinerve Nees (n = 18,  Digitaria argyrograpta (Nees Stapf (n = 9 and D. maitlandii Stapf & C.E. Hubb. (n = 9. Additional polyploid levels are described for Diplachne fusca (L. Beauv. ex Roem. & Schult. (n = 10 and Digitaria diagonalis (Nees Stapf var.  diagonalis (n = 9. B-chromosomes were observed in several different specimens. The presence of B-chromosomes often results in abnormal chromosomal behaviour during meiosis.

Expansion of deciduous tall shrubs but not evergreen dwarf shrubs inhibited by reindeer in Scandes mountain range.

Science.gov (United States)

Vowles, Tage; Gunnarsson, Bengt; Molau, Ulf; Hickler, Thomas; Klemedtsson, Leif; Björk, Robert G

2017-11-01

One of the most palpable effects of warming in Arctic ecosystems is shrub expansion above the tree line. However, previous studies have found that reindeer can influence plant community responses to warming and inhibit shrubification of the tundra.We revisited grazed (ambient) and ungrazed study plots (exclosures), at the southern as well as the northern limits of the Swedish alpine region, to study long-term grazing effects and vegetation changes in response to increasing temperatures between 1995 and 2011, in two vegetation types (shrub heath and mountain birch forest).In the field layer at the shrub heath sites, evergreen dwarf shrubs had increased in cover from 26% to 49% but were unaffected by grazing. Deciduous dwarf and tall shrubs also showed significant, though smaller, increases over time. At the birch forest sites, the increase was similar for evergreen dwarf shrubs (20-48%) but deciduous tall shrubs did not show the same consistent increase over time as in the shrub heath.The cover and height of the shrub layer were significantly greater in exclosures at the shrub heath sites, but no significant treatment effects were found on species richness or diversity.July soil temperatures and growing season thawing degree days (TDD) were higher in exclosures at all but one site, and there was a significant negative correlation between mean shrub layer height and soil TDD at the shrub heath sites. Synthesis . This study shows that shrub expansion is occurring rapidly in the Scandes mountain range, both above and below the tree line. Tall, deciduous shrubs had benefitted significantly from grazing exclosure, both in terms of cover and height, which in turn lowered summer soil temperatures. However, the overriding vegetation shift across our sites was the striking increase in evergreen dwarf shrubs, which were not influenced by grazing. As the effects of an increase in evergreen dwarf shrubs and more recalcitrant plant litter may to some degree counteract some of

Radiative transfer in shrub savanna sites in Niger: preliminary results from HAPEX-Sahel. 1. Modelling surface reflectance using a geometric-optical approach

International Nuclear Information System (INIS)

Franklin, J.; Duncan, J.; Huete, A.R.; Leeuwen, W.J.D. van; Li, X.; Bégué, A.

1994-01-01

To use optical remote sensing to monitor land surface-climate interactions over large areas, algorithms must be developed to relate multispectral measurements to key variables controlling the exchange of matter (water, carbon dioxide) and energy between the land surface and the atmosphere. The proportion of the ground covered by vegetation and the interception of photosynthetically active radiation (PAR) by vegetation are examples of two variables related to evapotranspiration and primary production, respectively. An areal-proportion model of the multispectral reflectance of shrub savanna, composed of scattered shrubs with a grass, forb or soil understory, predicted the reflectance of two 0.5 km 2 sites as the area-weighted average of the shrub and understory or ‘background’ reflectances. Although the shaded crown and shaded background have darker reflectances, ignoring them in the area-weighted model is not serious when shrub cover is low and solar zenith angle is small. A submodel predicted the reflectance of the shrub crown as a function of the foliage reflectance and amount of plant material within the crown, and the background reflectance scattered or transmitted through canopy gaps (referred to as a soil—plant ‘spectral interaction’ term). One may be able to combine these two models to estimate both the fraction of vegetation cover and interception of PAR by green vegetation in a shrub savanna. (author)

Chapter 22. Rosaceous shrubs

Science.gov (United States)

Nancy L. Shaw; Stephen B. Monsen; Richard Stevens

2004-01-01

Important shrubs of the Rose Family (Rosaceae) in the Intermountain region are distributed from blackbrush and salt desert shrub communities through high elevation forests and meadows. Growth habits of this group vary from trailing brambles to upright shrubs and small trees. Some species are evergreen while others are deciduous. Many of these species are highly valued...

[Soil moisture dynamics and water balance of Salix psammophila shrubs in south edge of Mu Us Sandy Land].

Science.gov (United States)

An, Hui; An, Yu

2011-09-01

Taking the artificial sand-fixing Salix psammophila shrubs with different plant density (0.2, 0.6, and 0.8 plants x m(-2)) in Mu Us Sandy Land as test objects, this paper studied the soil moisture dynamics and evapotranspiration during growth season. There existed obvious differences in the soil moisture dynamics and evapotranspiration among the shrubs. The soil moisture content changed in single-hump-shape with the increase of plant density, and in "S" shape during growth season, being closely correlated with precipitation. The evapotranspiration was the highest (114.5 mm) in the shrubs with a density 0.8 plants x m(-1), accounting for 90.8% of the total precipitation during growth season, and the lowest (109.7 mm) in the shrubs with a density 0.6 plants x m(-2) Based on the soil moisture dynamics and water balance characteristics, the appropriate planting density of S. psammophila shrubs in Mu Us Sandy Land could be 0.6 plants x m(-2).

Ecosystem responses to warming and watering in typical and desert steppes

OpenAIRE

Zhenzhu Xu; Yanhui Hou; Lihua Zhang; Tao Liu; Guangsheng Zhou

2016-01-01

Global warming is projected to continue, leading to intense fluctuations in precipitation and heat waves and thereby affecting the productivity and the relevant biological processes of grassland ecosystems. Here, we determined the functional responses to warming and altered precipitation in both typical and desert steppes. The results showed that watering markedly increased the aboveground net primary productivity (ANPP) in a typical steppe during a drier year and in a desert steppe over two ...

Their grass is greener but ours is sweeter - thoroughbred breeding and water management in the Upper Hunter region of New South Wales, Australia

Energy Technology Data Exchange (ETDEWEB)

McManus, P. [University of Sydney, Sydney, NSW (Australia). School for Geoscience

2008-05-15

The Upper Hunter region (in New South Wales (NSW) around Scone is reputed to be the second most significant thoroughbred breeding region in the world after the Bluegrass region of Kentucky. This article identifies the importance and cultural constructions of grass, and hence water, in the thoroughbred breeding industry in this region. Thoroughbred stud managers attempt to produce environments attractive to potential horse purchasers and owners with mares to be mated. These environments are constructed from perceptions of how a thoroughbred stud should appear, and from the physical conditions of specific locations. One perception is that the grass should be green. There are differing opinions in the thoroughbred breeding industry about the nutritional value of irrigated grasses, the role of these grasses in horse development and the associated access to, cost of and efficacy of water used for this purpose. The paper concludes that effective water management in this industry is only possible if various cultures of nature are understood, where necessary challenged, and subsequently included in policy and planning.

[Relationships between vegetation characteristics and soil properties at different restoration stages on slope land with purple soils in Hengyang of Hunan Province, South-central China].

Science.gov (United States)

Yang, Ning; Zou, Dong-Sheng; Yang, Man-Yuan; Hu, Li-Zhen; Zou, Fang-Ping; Song, Guang-Tao; Lin, Zhong-Gui

2013-01-01

By using space series to replace time series, this paper studied the relationships between the vegetation characteristics and soil properties at different restoration stages on the slope land with purple soils in Hengyang of Hunnan Province South-central China. There existed obvious differences in the soil physical and chemical properties at different restoration stages. From grassplot, grass-shrub, shrub to shrub-arbor, the soil organic matter, total and available N, and moisture contents increased markedly, soil bulk density had an obvious decrease, soil total and available P contents changed little, and soil pH decreased gradually, but no significant differences were observed among different restoration stages. At different restoration stages, the biomass of plant community had effects on the quantity and composition of soil microbes. The quantities of soil bacteria and fungi had significant positive correlations with the aboveground biomass of plant community, but the quantity of soil actinomycetes had less correlation with plant community's aboveground biomass. At different restoration stages, the activities of soil urease, protease, alkaline phosphatase, invertase, cellulase, catalase, and polyphenol oxidase decreased with increasing soil layer, and had significant positive correlations with plant community's richness and aboveground biomass.

Transitions and coexistence along a grazing gradient in the Eurasian steppe

Science.gov (United States)

Ren, Haiyan; Taube, Friedelm; Zhang, Yingjun; Bai, Yongfei; Hu, Shuijin

2017-04-01

Ecological resilience theory has often been applied to explain species coexistence and range condition assessment of various community states and to explicate the dynamics of ecosystems. Grazing is a primary disturbance that can alter rangeland resilience by causing hard-to-reverse transitions in grasslands. Yet, how grazing affects the coexistence of plant functional group (PFG) and transition remains unclear. We conducted a six-year grazing experiment in a typical steppe of Inner Mongolia, using seven grazing intensities (0, 1.5, 3.0, 4.5, 6.0, 7.5 and 9.0 sheep/ hectare) and two grazing systems (i.e. a continuous annual grazing as in the traditional grazing system, and a mixed grazing system combining grazing and haymaking), to examine grazing effects on plant functional group shifts and species coexistence in the semi-arid grassland system. Our results indicate that the relative richness of dominant bunchgrasses and forbs had a compensatory coexistence at all grazing intensities, and the richness of rhizomatous grasses fluctuated but was persistent. The relative productivity of dominant bunchgrasses and rhizomatous grasses had compensatory interactions with grazing intensity and grazing system. Dominant bunchgrasses and rhizomatous grasses resist grazing effects by using their dominant species functional traits: high specific leaf area and low leaf nitrogen content. Our results suggest that: 1. Stabilizing mechanisms beyond grazing management are more important in determining plant functional group coexistence and ecological resilience. 2. Plant functional group composition is more important in influencing ecosystem functioning than diversity. 3. Ecosystem resilience at a given level is related to the biomass of dominant PFG, which is determined by a balanced shift between dominant species biomass. The relatively even ecosystem resilience along the grazing gradient is attributed to the compensatory interactions of dominant species in their biomass variations

Interactions between Shrubs and Permafrost in the Torngat Mountains, Northern Labrador, Canada

Science.gov (United States)

Lewkowicz, A.; Way, R. G.; Hermanutz, L.; Trant, A.; Siegwart Collier, L.; Whitaker, D.

2017-12-01

Discontinuous permafrost is acutely sensitive to climate warming and vegetation dynamics. Shrub height is positively correlated with accumulation of snow in the tundra resulting in warming of the ground in winter, and greater shading and lower surface temperatures in summer. Rapid greening due to climate warming has been observed throughout northeastern Canada and particularly in the coastal mountainous terrain of the Torngat Mountains National Park. Our research examines how this shrubification in the Torngat Mountains is modifying permafrost characteristics using observations which extend over a 100 km south-north transect from the sporadic zone (Saglek, Torr Bay) to where permafrost is widespread (Nakvak Brook, Kangalaksiorvik Lake) and potentially continuous (Komaktorvik River). We use air and ground temperature monitoring, vegetation surveys, dendrochronology, frost probing and electrical resistivity tomography (ERT) to describe the complex interactions between shrub growth, geomorphology, climate and permafrost in a region where climate warming is rapidly altering the landscape. Preliminary analysis of field data shows low resistivity anomalies in the ERT profiles at some sites with thin permafrost, interpreted as unfrozen zones correlated with areas of tall shrubs (Alnus spp., Salix spp. and Betula glandulosa; ranging from prostrate to 2 m). Elsewhere, high resistivities extend to the base of the ERT profiles, indicating thicker permafrost, and no obvious impact of medium to low-prostrate shrubs (Salix spp., Betula glandulosa, Rhododendron spp., and Vaccinium spp.; up to 50 cm). Permafrost is interpreted to be present at most sites with low or prostrate shrubs, except where hydrological conditions favour warmer ground temperatures. We infer that the net impact of increasing shrub heights on the active layer and permafrost depends on antecedent ground temperatures and surficial geology. Increasing shrub heights may cause permafrost degradation at sites where

A Contribution to Insect Studies in Ikh Nart Nature Reserve, Mongolia: Vespid Wasps (Hymenoptera, Vespidae

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Batchuluun Buyanjargal

2018-06-01

Full Text Available Ikh Nart Nature Reserve remains poorly studied for invertebrates, especially for vespid wasps. A total of 14 vespid species belonging to seven genera of the subfamily Eumeninae were recorded from diff erent habitats (rocky outcrops, springs, tall vegetation habitats, shrub-lands and short grass steppes in the nature reserve during three-year studies (2015-2017. These species represent 27 percent of the vespid fauna of the desert-steppe zone of Mongolia. We found the highest species richness in areas where water was available (near springs and wells, and the lowest richness in habitats with tall vegetation. Among the diff erent habitat types, vespid species composition was most similar (91% shared species between rocky outcrops and spring habitats. Six vespid species range from Kazakhstan to Mongolian, and one species is sub-endemic to Mongolia. Availability of water sources and nesting sites were possibly the main factors infl uencing the distribution of vespid wasps. It is necessary to conduct comprehensive research into the insect community of Ikh Nart Nature Reserve.

Dynamics of woody vegetation in a semi-arid savanna, with a focus ...

African Journals Online (AJOL)

Increases in the tree:grass ratio with accompanying changes in herbaceous composition, called bush or shrub encroachment, is a worldwide phenomenon in ... Acacia mellifera-dominated savannas in the Northern Cape, South Africa, were investigated by means of vegetation classification and analyses of sequential aerial ...

Interactive effects of warming and increased precipitation on community structure and composition in an annual forb dominated desert steppe.

Directory of Open Access Journals (Sweden)

Yanhui Hou

Full Text Available To better understand how warming, increased precipitation and their interactions influence community structure and composition, a field experiment simulating hydrothermal interactions was conducted at an annual forb dominated desert steppe in northern China over 2 years. Increased precipitation increased species richness while warming significantly decreased species richness, and their effects were additive rather than interactive. Although interannual variations in weather conditions may have a major affect on plant community composition on short term experiments, warming and precipitation treatments affected individual species and functional group composition. Warming caused C4 grasses such as Cleistogenes squarrosa to increase while increased precipitation caused the proportions of non-perennial C3 plants like Artemisia capillaris to decrease and perennial C4 plants to increase.

Humid to arid to subhumid vegetation shift on Pilliga Sandstone, Ulungra Springs, New South Wales

Science.gov (United States)

Dodson, J. R.; Wright, R. V. S.

1989-09-01

The Pilliga Sandstone region of the northwest slope of New South Wales has a natural vegetation cover of sclerophyllous relatively closed to open forests with a largely heathy understorey, and a warm, subhumid and continental climate. Pollen analysis of spring-fed deposits gives a vegetation history extending from at least 30,000 yr B.P. to the late Holocene. Tree pollen became scarce after about 25,000 yr B.P. and an assemblage dominated by Chenopodiaceae, Liguliflorae, Tubuliflorae, and probably Poaceae developed. No similar assemblage is known from present pollen rain studies carried out in Australia. However, it clearly represents a treeless open shrub-steppe formation and therefore an arid or semiarid environment. The site thus provides evidence of an eastward late Pleistocene extension of the arid zone in Australia, and is the first full-glacial vegetation record between 20° and 35° latitude in Australia. The present vegetation cover did not become reestablished until the beginning of the Holocene, which raises questions about the form in which Pilliga Sandstone vegetation survived full-glacial conditions.

Linking phenology and biomass productivity in South Dakota mixed-grass prairie

Science.gov (United States)

Rigge, Matthew; Smart, Alexander; Wylie, Bruce; Gilmanov, Tagir; Johnson, Patricia

2013-01-01

Assessing the health of rangeland ecosystems based solely on annual biomass production does not fully describe plant community condition; the phenology of production can provide inferences on species composition, successional stage, and grazing impacts. We evaluate the productivity and phenology of western South Dakota mixed-grass prairie using 2000 to 2008 Moderate Resolution Imaging Spectrometer (MODIS) normalized difference vegetation index (NDVI) satellite imagery at 250 m spatial resolution. Growing season NDVI images were integrated weekly to produce time-integrated NDVI (TIN), a proxy of total annual biomass production, and integrated seasonally to represent annual production by cool (C3) and warm (C4) season species. Additionally, a variety of phenological indicators including cool season percentage of TIN were derived from the seasonal profiles of NDVI. Cool season percentage and TIN were combined to generate vegetation classes, which served as proxies of plant community condition. TIN decreased with precipitation from east to west across the study area. Alternatively, cool season percentage increased from east to west, following patterns related to the reliability (interannual coefficient of variation [CV]) and quantity of mid-summer precipitation. Cool season TIN averaged 76.8% of total. Seasonal accumulation of TIN corresponded closely (R2 > 0.90) to that of gross photosynthesis data from a carbon flux tower. Field-collected biomass and community composition data were strongly related to the TIN and cool season percentage products. The patterns of vegetation classes were responsive to topographic, edaphic, and land management influences on plant communities. Accurate maps of biomass production, cool/warm season composition, and vegetation classes can improve the efficiency of land management by adjusting stocking rates and season of use to maximize rangeland productivity and achieve conservation objectives. Further, our results clarify the spatial and

Retaining of botanical diversity of steppe ecosystems at the Semipalatinsk test site area

International Nuclear Information System (INIS)

Sultanova, B.M.

2005-01-01

The nuclear tests conducted on the STS area have an effect on steppe biome. Regime of military secrecy allowed retaining extensive diversity of steppe vegetation at the area of the former Semipalatinsk test site, although the vegetation was liquidated in the most part of Kazakhstan. Unique biologic diversity of the steppe vegetation requires status of particularly secured vegetation of the STS area. (author)

Participatory Mapping of Terrestrial Fishery Resources in Kwale ...

African Journals Online (AJOL)

The study focused on the spatial arrangement, access, ownership and use of land-based resources, mainly shrubs, grasses and trees, at four landing sites along the north-south population gradient. Participatory techniques (sketch maps, livelihood diagrams and transect walks) were applied, where trained fishers led other ...

Attempting to restore herbaceous understories in Wyoming big sagebrush communities with mowing and seeding

Science.gov (United States)

Shrub steppe communities with depleted perennial herbaceous understories need to be restored to increase resilience, provide quality wildlife habitat, and improve ecosystem function. Mowing has been applied to Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle &Young) steppe...

Legume Shrubs Are More Nitrogen-Homeostatic than Non-legume Shrubs

OpenAIRE

Guo, Yanpei; Yang, Xian; Schöb, Christian; Jiang, Youxu; Tang, Zhiyao

2017-01-01

Legumes are characterized as keeping stable nutrient supply under nutrient-limited conditions. However, few studies examined the legumes' stoichiometric advantages over other plants across various taxa in natural ecosystems. We explored differences in nitrogen (N) and phosphorus (P) stoichiometry of different tissue types (leaf, stem, and root) between N2-fixing legume shrubs and non-N2-fixing shrubs from 299 broadleaved deciduous shrubland sites in northern China. After excluding effects of ...

Effects of elevated CO₂, warming and precipitation change on plant growth, photosynthesis and peroxidation in dominant species from North China grassland.

Science.gov (United States)

Xu, Zhenzhu; Shimizu, Hideyuki; Ito, Shoko; Yagasaki, Yasumi; Zou, Chunjing; Zhou, Guangsheng; Zheng, Yuanrun

2014-02-01

Warming, watering and elevated atmospheric CO₂-concentration effects have been extensively studied separately; however, their combined impact on plants is not well understood. In the current research, we examined plant growth and physiological responses of three dominant species from the Eurasian Steppe with different functional traits to a combination of elevated CO₂, high temperature, and four simulated precipitation patterns. Elevated CO₂ stimulated plant growth by 10.8-41.7 % for a C₃ leguminous shrub, Caragana microphylla, and by 33.2-52.3 % for a C₃ grass, Stipa grandis, across all temperature and watering treatments. Elevated CO₂, however, did not affect plant biomass of a C₄ grass, Cleistogenes squarrosa, under normal or increased precipitation, whereas a 20.0-69.7 % stimulation of growth occurred with elevated CO₂ under drought conditions. Plant growth was enhanced in the C₃ shrub and the C₄ grass by warming under normal precipitation, but declined drastically with severe drought. The effects of elevated CO₂ on leaf traits, biomass allocation and photosynthetic potential were remarkably species-dependent. Suppression of photosynthetic activity, and enhancement of cell peroxidation by a combination of warming and severe drought, were partly alleviated by elevated CO₂. The relationships between plant functional traits and physiological activities and their responses to climate change were discussed. The present results suggested that the response to CO₂ enrichment may strongly depend on the response of specific species under varying patterns of precipitation, with or without warming, highlighting that individual species and multifactor dependencies must be considered in a projection of terrestrial ecosystem response to climatic change.

Effects of Applied Land Use Strategies on Farmland Soils in the Southwestern Siberian Kulunda-Steppe

Science.gov (United States)

Grunwald, Lars-Christian; Illiger, Patrick; Stephan, Eckart; Frühauf, Manfred

2014-05-01

The Kulunda steppe in southwestern Siberia is one of the most intensely used agricultural regions in the world. The study area of the KULUNDA project is the Kulunda steppe, which is a part of the conversion region created during the so called "virgin land campaign" in the soviet era. Nowadays it is characterized by widespread soil degradation. Despite the fact that agriculture is the basis of existence, land use practice is maladjusted to the local conditions. The widespread soil degradation and accordingly the decreased soil humus content have negative effects on crop yields in this region. With respect to climate change, the current study analyses the cause effect relationship between land use practice and soil properties. In particular, different methods of soil cultivation will be tested and for each of the cases the soil humus content, soil water, soil solute balance will be measured and compared. In addition, the possibilities of soil carbon sequestration capacity will be analyzed. Furthermore, the study aims to achieve properly adapted sustainable cropping systems to stabilize the yields and to increase the productivity of plant production per spatial unit in this high vulnerable dry farming region. In 2012 the long term field trials started at three test farms in different steppe biomes, containing different soil types from chernozems to kastanozems. Each of them is characterized by a negative water balance. Successfully running cropping models, such as crop rotation, tilling intensity, plant protection and nutrition strategies from south Canadian steppe regions were adapted to regional agronomic needs. The traditional Russian cultivation system will be compared with two modern systems, including no-tillage methods on specially randomized test plots. Additionally, these plots are equipped with soil moisture monitoring systems to analyze the soil water content in different depths under the different cropping methods. The expected results will not only deepen

Eder Acquisition 2007 Habitat Evaluation Procedures Report.

Energy Technology Data Exchange (ETDEWEB)

Ashley, Paul R.

2008-01-01

A habitat evaluation procedures (HEP) analysis was conducted on the Eder acquisition in July 2007 to determine how many protection habitat units to credit Bonneville Power Administration (BPA) for providing funds to acquire the project site as partial mitigation for habitat losses associated with construction of Grand Coulee and Chief Joseph Dams. Baseline HEP surveys generated 3,857.64 habitat units or 1.16 HUs per acre. HEP surveys also served to document general habitat conditions. Survey results indicated that the herbaceous plant community lacked forbs species, which may be due to both livestock grazing and the late timing of the surveys. Moreover, the herbaceous plant community lacked structure based on lower than expected visual obstruction readings (VOR); likely a direct result of livestock impacts. In addition, introduced herbaceous vegetation including cultivated pasture grasses, e.g. crested wheatgrass and/or invader species such as cheatgrass and mustard, were present on most areas surveyed. The shrub element within the shrubsteppe cover type was generally a mosaic of moderate to dense shrubby areas interspersed with open grassland communities while the 'steppe' component was almost entirely devoid of shrubs. Riparian shrub and forest areas were somewhat stressed by livestock. Moreover, shrub and tree communities along the lower reaches of Nine Mile Creek suffered from lack of water due to the previous landowners 'piping' water out of the stream channel.

Climatically driven loss of calcium in steppe soil as a sink for atmospheric carbon

Science.gov (United States)

A.G. Lapenis; G.B. Lawrence; S.W. Bailey; B.F. Aparin; A.I. Shiklomanov; N.A. Speranskaya; M.S. Torn; M. Calef

2008-01-01

During the last several thousand years the semi-arid, cold climate of the Russian steppe formed highly fertile soils rich in organic carbon and calcium (classified as Chernozems in the Russian system). Analysis of archived soil samples collected in Kemannaya Steppe Preserve in 1920, 1947, 1970, and fresh samples collected in 1998 indicated that the native steppe...

Light use efficiency over two temperate steppes in inner Mongolia, China.

Directory of Open Access Journals (Sweden)

Yu Wang

Full Text Available Vegetation light use efficiency (LUE is a key parameter of Production Efficiency Models (PEMs for simulating gross primary production (GPP of vegetation, from regional to global scales. Previous studies suggest that grasslands have the largest inter-site variation of LUE and controlling factors of grassland LUE differ from those of other biomes, since grasslands are usually water-limited ecosystems. Combining eddy covariance flux data with the fraction of photosynthetically active radiation absorbed by the plant canopy from MODIS, we report LUE on a typical steppe and a desert steppe in Inner Mongolia, northern China. Results show that both annual average LUE and maximum LUE were higher on the desert steppe (0.51 and 1.13 g C MJ(-1 than on the typical steppe (0.34 and 0.88 g C MJ(-1, despite the higher GPP of the latter. Water availability was the primary limiting factor of LUE at both sites. Evaporative fraction (EF or the ratio of actual evapotranspiration to potential evapotranspiration (AET/PET can explain 50-70% of seasonal LUE variations at both sites. However, the slope of linear regression between LUE and EF (or AET/PET differed significantly between the two sites. LUE increased with the diffuse radiation ratio on the typical steppe; however, such a trend was not found for the desert steppe. Our results suggest that a biome-dependent LUE(max is inappropriate, because of the large inter-site difference of LUE(max within the biome. EF could be a promising down-regulator on grassland LUE for PEMs, but there may be a site-specific relationship between LUE and EF.

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

Restoration of mountain big sagebrush steppe following prescribed burning to control western juniper.

Science.gov (United States)

Davies, K W; Bates, J D; Madsen, M D; Nafus, A M

2014-05-01

Western juniper (Juniperus occidentalis ssp. occidentalis Hook) encroachment into mountain big sagebrush (Artemisia tridentata spp. vaseyana (Rydb.) Beetle) steppe has reduced livestock forage production, increased erosion risk, and degraded sagebrush-associated wildlife habitat. Western juniper has been successfully controlled with partial cutting followed by prescribed burning the next fall, but the herbaceous understory and sagebrush may be slow to recover. We evaluated the effectiveness of seeding perennial herbaceous vegetation and sagebrush at five sites where juniper was controlled by partially cutting and prescribed burning. Treatments tested at each site included an unseeded control, herbaceous seed mix (aerially seeded), and the herbaceous seed mix plus sagebrush seed. In the third year post-treatment, perennial grass cover and density were twice as high in plots receiving the herbaceous seed mix compared to the control plots. Sagebrush cover and density in the sagebrush seeded plots were between 74- and 290-fold and 62- and 155-fold greater than the other treatments. By the third year after treatment, sagebrush cover was as high as 12 % in the sagebrush seeded plots and between 0 % and 0.4 % where it was not seeded. These results indicate that aerial seeding perennial herbaceous vegetation can accelerate the recovery of perennial grasses which likely stabilize the site. Our results also suggest that seeding mountain big sagebrush after prescribed burning encroaching juniper can rapidly recover sagebrush cover and density. In areas where sagebrush habitat is limited, seeding sagebrush after juniper control may increase sagebrush habitat and decrease the risks to sagebrush-associated species.

Competition between a Lawn-Forming Cynodon dactylon and a Tufted Grass Species Hyparrhenia hirta on a South-African Dystrophic Savanna.

Science.gov (United States)

Zwerts, J A; Prins, H H T; Bomhoff, D; Verhagen, I; Swart, J M; de Boer, W F

2015-01-01

South African savanna grasslands are often characterised by indigestible tufted grass species whereas lawn grasses are far more desirable in terms of herbivore sustenance. We aimed to investigate the role of nutrients and/or the disturbance (grazing, trampling) by herbivores on the formation of grazing lawns. We conducted a series of common garden experiments to test the effect of nutrients on interspecific competition between a typical lawn-forming grass species (Cynodon dactylon) and a species that is frequently found outside grazing lawns (Hyparrhenia hirta), and tested for the effect of herbivore disturbance in the form of trampling and clipping. We also performed a vegetation and herbivore survey to apply experimentally derived insights to field observations. Our results showed that interspecific competition was not affected by soil nutrient concentrations. C. dactylon did show much more resilience to disturbance than H. hirta, presumably due to the regenerative capacity of its rhizomes. Results from the field survey were in line with these findings, describing a correlation between herbivore pressure and C. dactylon abundance. We conclude that herbivore disturbance, and not soil nutrients, provide C. dactylon with a competitive advantage over H. hirta, due to vegetative regeneration from its rhizomes. This provides evidence for the importance of concentrated, high herbivore densities for the creation and maintenance of grazing lawns.

Modelling the dynamics of total precipitation and aboveground net primary production of fescue-feather grass steppe at Askania Nova according to global climate change scenariosModelling the dynamics of total precipitation and aboveground net primary production of fescue-feather grass steppe at Askania Nova according to global climate change scenarios

Directory of Open Access Journals (Sweden)

S. O. Belyakov

2017-01-01

Full Text Available This article discusses modelling of Aboveground Net Primary Production (ANPP of steppe (arid grassland ecosystems plant species in relation to changes in total precipitation over the previous year at the “Stara” study site, Biosphere Reserve “Askania-Nova”, Khersonregion (Ukraine. To investigate linkages between precipitation and Aboveground Net Primary Production, correlation analysis was chosen and a time series regression analysis was based on the data set for the period 1988–2012. The NPP dependence on quantity of precipitation was found to be more significant for the previous autumn-winter-spring period (AWSP than for the previous 12 month period. A regression model of ANPP’s dependence on AWSP is proposed. This model was further validated by the authors’ samples of ANPP, collected at the “Stara” study site in 2013–2016. The regression model showed a non-linear (quadratic dependence of net primary production of zonal and intrazonal plant coenoses and total precipitation for the autumn-winter-spring period for arid grasslands with a coefficient of determination equal to 0.54 and significance level less than 0.05. The non-linear equation for these relations, visualized by a parabola curve, was calculated using the Nonlinear Least-Squares Regression Method. The data set, based on calculated predicted values, using the calculated equation, had a similar dynamic to the historical data on ANPP, but the model could not predict critical values. For this reason, additional studies are required for critical precipitation events. Non-linear response, investigated according to regression analysis, reveals optimal zones of plant growth, depending on the total precipitation level before the vegetation peak. For research areas where the dominant species are the turf grasses Stipa ucrainica P. Smirn., S. capillata L., S. lessingiana Trin. & Rupr., Festuca valesiaca Gaudin, Koeleria cristata (L. Pers. the optimal precipitation rates

Nowcasting daily minimum air and grass temperature

Science.gov (United States)

Savage, M. J.

2016-02-01

Site-specific and accurate prediction of daily minimum air and grass temperatures, made available online several hours before their occurrence, would be of significant benefit to several economic sectors and for planning human activities. Site-specific and reasonably accurate nowcasts of daily minimum temperature several hours before its occurrence, using measured sub-hourly temperatures hours earlier in the morning as model inputs, was investigated. Various temperature models were tested for their ability to accurately nowcast daily minimum temperatures 2 or 4 h before sunrise. Temperature datasets used for the model nowcasts included sub-hourly grass and grass-surface (infrared) temperatures from one location in South Africa and air temperature from four subtropical sites varying in altitude (USA and South Africa) and from one site in central sub-Saharan Africa. Nowcast models used employed either exponential or square root functions to describe the rate of nighttime temperature decrease but inverted so as to determine the minimum temperature. The models were also applied in near real-time using an open web-based system to display the nowcasts. Extrapolation algorithms for the site-specific nowcasts were also implemented in a datalogger in an innovative and mathematically consistent manner. Comparison of model 1 (exponential) nowcasts vs measured daily minima air temperatures yielded root mean square errors (RMSEs) <1 °C for the 2-h ahead nowcasts. Model 2 (also exponential), for which a constant model coefficient ( b = 2.2) was used, was usually slightly less accurate but still with RMSEs <1 °C. Use of model 3 (square root) yielded increased RMSEs for the 2-h ahead comparisons between nowcasted and measured daily minima air temperature, increasing to 1.4 °C for some sites. For all sites for all models, the comparisons for the 4-h ahead air temperature nowcasts generally yielded increased RMSEs, <2.1 °C. Comparisons for all model nowcasts of the daily grass

Contrasting shrub species respond to early summer temperatures leading to correspondence of shrub growth patterns

Science.gov (United States)

Weijers, Stef; Pape, Roland; Löffler, Jörg; Myers-Smith, Isla H.

2018-03-01

The Arctic-alpine biome is warming rapidly, resulting in a gradual replacement of low statured species by taller woody species in many tundra ecosystems. In northwest North America, the remotely sensed normalized difference vegetation index (NDVI), suggests an increase in productivity of the Arctic and alpine tundra and a decrease in productivity of boreal forests. However, the responses of contrasting shrub species growing at the same sites to climate drivers remain largely unexplored. Here, we test growth, climate, and NDVI relationships of two contrasting species: the expanding tall deciduous shrub Salix pulchra and the circumarctic evergreen dwarf shrub Cassiope tetragona from an alpine tundra site in the Pika valley in the Kluane Region, southwest Yukon Territories, Canada. We found that annual growth variability of both species at this site is strongly driven by early summer temperatures, despite their contrasting traits and habitats. Shrub growth chronologies for both species were correlated with the regional climate signal and showed spatial correspondence with interannual variation in NDVI in surrounding alpine and Arctic regions. Our results suggest that early summer warming represents a common driver of vegetation change for contrasting shrub species growing in different habitats in the same alpine environments.

Meta-Analysis of Land Use / Land Cover Change Factors in the Conterminous US and Prediction of Potential Working Timberlands in the US South from FIA Inventory Plots and NLCD Cover Maps

Science.gov (United States)

Jeuck, James A.

-analysis provides insight into the general success of econometric independent variables for future forest use or cover change research. The second part of this dissertation developed a method for predicting area estimates and spatial distribution of PWT in the US South. This technique determined land use from USFS Forest Inventory and Analysis (FIA) and land cover from the National Land Cover Database (NLCD). Three dependent variable forms (DV Forms) were derived from the FIA data: DV Form 1, timberland, other; DV Form 2, short timberland, tall timberland, agriculture, other; and DV Form 3, short hardwood (HW) timberland, tall HW timberland, short softwood (SW) timberland, tall SW timberland, agriculture, other. The prediction accuracy of each DV Form was investigated using both random forest model and logistic regression model specifications and data optimization techniques. Model verification employing a "leave-group-out" Monte Carlo simulation determined the selection of a stratified version of the random forest model using one-year NLCD observations with an overall accuracy of 0.53-0.94. The lower accuracy side of the range was when predictions were made from an aggregated NLCD land cover class "grass_shrub". The selected model specification was run using 2011 NLCD and the other predictor variables to produce three levels of timberland prediction and probability maps for the US South. Spatial masks removed areas unlikely to be working forests (protected and urbanized lands) resulting in PWT maps. The area of the resulting maps compared well with USFS area estimates and masked PWT maps and had an 8-11% reduction of the USFS timberland estimate for the US South compared to the DV Form. Change analysis of the 2011 NLCD to PWT showed (1) the majority of the short timberland came from NLCD grass_shrub; (2) the majority of NLCD grass_shrub predicted into tall timberland, and (3) NLCD grass_shrub was more strongly associated with timberland in the Coastal Plain. Resulting map products

Effects of sub-Arctic shrub canopies on snowmelt energetics

Science.gov (United States)

Bewley, D.; Essery, R.; Pomeroy, J.

2006-12-01

Much of the low Arctic is covered with shrub tundra, and there is increasing evidence that snowmelt rates are substantially different between shrub tundra and poorly vegetated sites. The cause of this remains uncertain, however, and extends beyond simple differences in albedo. Results are presented in this study from a detailed field investigation at Wolf Creek Research Basin in 2004 to determine the effect of two different shrub canopy structures on both melt rates and the partitioning of melt energy. The low shrub site (LSS) was essentially an unvegetated snowfield prior to melt (mean albedo ~0.85), and shrubs only became exposed during the last few days of melt reaching a mean height of 0.31 m and mean Plant Area Index (PAI) of 0.32. Shrubs at the tall shrub site (TSS) were partially buried initially (shrub fraction, mean height and PAI of 0.2, 0.9 m and 0.41) but dominated the landscape by the end of melt (corresponding values of 0.71, 1.6 m and 0.6). Melt rates were higher at TSS up until the exposure of shrubs and bare ground at LSS, after which the rates converged. A Shrub-Snow Canopy Model (SSCM) is developed to improve snowmelt simulations for shrub canopies by parameterizing the key shrub effects on surface fluxes, including the extinction of shortwave irradiance beneath shrubs and in canopy gaps, and the enhancement of snow surface fluxes of longwave radiation and sensible heat. SSCM was run for LSS assuming no shrubs were present above the variable snow and bare ground tiles, whereas for TSS an increasing shrub fraction above each tile was prescribed from observations. Results from both sites suggest that sensible heat fluxes contributed more melt energy than net radiation, and were greater during early melt at TSS due to the warming of exposed shrubs. SWE was accurately predicted against transect measurements at TSS (rms error 4 mm), but was overestimated at LSS (rms error 13 mm) since both air temperatures and turbulent transport were underestimated

Soil and grass contamination with cesium in South Germany and the winter feed 1986/1987. Die Caesium-Boden- und Graskontamination in Sueddeutschland und die Winterfuetterung 1986/1987

Energy Technology Data Exchange (ETDEWEB)

Schmidt, M; Giegrich, J; Franke, B

1986-01-01

The data for soil and grass contamination with Cs-137 and Cs-134 by the nuclear accident in Chernobyl have been analyzed for the two federal states of Baden-Wuerttemberg and Bavaria. Large regional variations have been determined, with peak values for ground activity of 36,000 Bq/m/sup 2/ in Southern Bavaria and of 24,000 Bq/m/sup 2/ in the South-East of Baden-Wuerttemberg. The average grass contamination in Baden-Wuerttemberg varied between 170 Bq and 620 Bq per kg fresh weight. The grass contamination in Bavaria was estimated between 200 and 1,000 Bq/kg. Due to the large amount of radioactivity in grass, high quantities of contaminated hay and silage will be used for winter cattle feed and thus will be found in milk and meat products from Southern Germany. Over the 6 winter months, a total of 15.10/sup 12/ Bq Cs-137 will be fed to cattle. This would lead to a calculated average milk concentration of Cs-137 of 250 Bq/l in Bavaria and of 120 Bq/l in Baden-Wuerttemberg.

Reduction in clover-grass yield caused by different traffic intensities

DEFF Research Database (Denmark)

Green, Ole; Jørgensen, Rasmus Nyholm; Kristensen, Kristian

Different traffic intensities have been shown to have a negative influence on the yield of grass and clover. A full scale grass-clover field trial was established to estimate the effect on clover-grass yields as a function of different wheel loads and tire pressures. The trial comprised 16...... close to the north, south and east border of the field. No significant interactions were found between the timing of crop and soil damage as affected by wheel load and tire pressure. However, at specific times, there was a significant effect of wheel load and secondary by the tire pressure. At all...... measurement times, the yield was lower using a wheel load of 4745 kg than for a wheel load of 2865 kg.     Key words (for Electronic Reference Library) Traffic intensities, tire load/pressure, clover/grass, yield loss, ...

Post-fire redistribution of soil carbon and nitrogen at a grassland-shrubland ecotone

Science.gov (United States)

Wang, Guan; Li, Junran; Ravi, Sujith; Dukes, David; Gonzales, Howell B.; Sankey, Joel B.

2018-01-01

The rapid conversion of grasslands into shrublands has been observed in many arid and semiarid regions worldwide. Studies have shown that fire can provide certain forms of reversibility for shrub-grass transition due to resource homogenization and shrub mortality, especially in the early stages of shrub encroachment. Field-level post-fire soil resource redistribution has rarely been tested. Here we used prescribed fire in a shrubland-grassland transition zone in the northern Chihuahuan Desert to test the hypothesis that fire facilitates the remobilization of nutrient-enriched soil from shrub microsites to grass and bare microsites and thereby reduces the spatial heterogeneity of soil resources. Results show that the shrub microsites had the lowest water content compared to grass and bare microsites after fire, even when rain events occurred. Significant differences of total soil carbon (TC) and total soil nitrogen (TN) among the three microsites disappeared one year after the fire. The spatial autocorrelation distance increased from 1~2 m, approximately the mean size of an individual shrub canopy, to over 5 m one year after the fire for TC and TN. Patches of high soil C and N decomposed one year after the prescribed fire. Overall, fire stimulates the transfer of soil C and N from shrub microsites to nutrient-depleted grass and bare microsites. Such a redistribution of soil C and N, coupled with the reduced soil water content under the shrub canopies, suggests that fire might influence the competition between shrubs and grasses, leading to a higher grass, compared to shrub, coverage in this ecotone.

Habitat selection of a declining white-tailed deer herd in the central Black Hills, South Dakota and Wyoming

Science.gov (United States)

Deperno, Christopher Shannon

Habitat selection, survival rates, the Black Hills National Forest Habitat Capability Model (HABCAP), and the USDA Forest Service Geographic Information System (GIS) data base were evaluated for a declining white-tailed deer (Odocoileus virginianus dacotensis) herd in the central Black Hills of South Dakota and Wyoming. From July 1993 through July 1996, 73 adult and yearling female and 12 adult and yearling male white-tailed deer were radiocollared and visually monitored. Habitat information was collected at 4,662 white-tailed deer locations and 1,087 random locations. Natural mortality (71%) was the primary cause of female mortality, followed by harvest (22.5%) and accidental causes (6.5%). More females died in spring (53.2%) than in fall (22.6%), winter (14.5%), or summer (9.7%). Male mortality resulted from hunting in fall (66.7%) and natural causes in spring (33.3%). Survival rates for all deer by year were 62.1% in 1993, 51.1% in 1994, 56.4% in 1995, and 53.9% in 1996 and were similar (P = 0.691) across years. During winter, white-tailed deer selected ponderosa pine- (Pinus ponderosa ) deciduous and burned pine cover types. Overstory-understory habitats selected included pine/grass-forb, pine/bearberry (Arctostaphylos uva-ursi), pine/snowberry (Symphoricarpos albus), burned pine/grass-forb, and pine/shrub habitats. Structural stages selected included sapling-pole pine stands with >70% canopy cover, burned pine sapling-pole and saw-timber stands with 40% canopy cover and all sapling-pole pine structural stages; sapling-pole stands with >70% canopy cover received the greatest use. White-tailed deer primarily fed in pine saw-timber structural stage with less than 40% canopy cover. Overall, selected habitats contained lower amounts of grass/forb, shrubs, and litter than random locations. Male and female deer generally bedded in areas that were characterized by greater horizontal cover than feeding and random sites. When feeding and bedding sites were combined

A habitat map of the Kalahari Gemsbok National Park

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J. Du P. Bothma

1973-07-01

Full Text Available The Kalahari Gemsbok National Park exhibits some six major habitats. Away from the river beds the tree savanna is limited to the northern corner of the park, consisting of Acacia girajfae woodland and scattered dunes. The Nossob and Auobriverbeds and adjacent areas also harbour A. girqffae except in the south where A. haematoxylon becomes dominant, and where the Karoo flora increases. The dunes covered with trees and shrubs usually support Boscia albitrunca, A. mellifera and an occasional A. girqffae. Where the dunes are superficially without shrub vegetation, Stipagrostis amabilis is dominant, although low, shrub-like A. haematoxylon also occurs. The plains also contain low A. haematoxylon shrub and several dominant grasses. Pans are abundantand their vegetation is usually characterized by stands of Rhigozum trichotomum and Monechma incanum.

Root systems of chaparral shrubs.

Science.gov (United States)

Kummerow, Jochen; Krause, David; Jow, William

1977-06-01

Root systems of chaparral shrubs were excavated from a 70 m 2 plot of a mixed chaparral stand located on a north-facing slope in San Diego County (32°54' N; 900 m above sea level). The main shrub species present were Adenostoma fasciculatum, Arctostaphylos pungens, Ceanothus greggii, Erigonum fasciculatum, and Haplopappus pinifolius. Shrubs were wired into their positions, and the soil was washed out beneath them down to a depth of approximately 60 cm, where impenetrable granite impeded further washing and root growth was severely restricted. Spacing and interweaving of root systems were recorded by an in-scale drawing. The roots were harvested in accordance to their depths, separated into diameter size classes for each species, and their dry weights measured. Roots of shrubs were largely confined to the upper soil levels. The roots of Eriogonum fasciculatum were concentrated in the upper soil layer. Roots of Adenostoma fasciculatum tended to be more superficial than those from Ceanothus greggii. It is hypothesized that the shallow soil at the excavation site impeded a clear depth zonation of the different root systems. The average dry weight root:shoot ratio was 0.6, ranging for the individual shrubs from 0.8 to 0.4. The root area always exceeded the shoot area, with the corresponding ratios ranging from 6 for Arctostaphylos pungens to 40 for Haplopappus pinifolius. The fine root density of 64 g dry weight per m 2 under the canopy was significantly higher than in the unshaded area. However, the corresponding value of 45 g dry weight per m 2 for the open ground is still high enough to make the establishment of other shrubs difficult.

Mapping of Vegetation with the Geoinformation System and Determining of Carrying Capacity of the Pre-Urals Steppe area for a Newly Establishing Population of the Przewalski Horse Equus ferus przewalskii at the Orenburg State Nature Reserve

Science.gov (United States)

Fedorov, N. I.; Mikhailenko, O. I.; Zharkikh, T. L.; Bakirova, R. T.

2018-01-01

Mapping of the vegetation (1:25000) of the Pre-Urals Steppe area at the Orenburg State Nature Reserve was completed in 2016. A map created with the geoinformation system contains 1931 simple and complex polygons for 25 types of vegetation. In a drought year, the average stock of palatable vegetation of the whole area is estimated at 8380 tons dry weight. The estimation is based on the size of areas covered by different types of vegetation, their grass production, the correction coefficients for decreasing of pasture forage stocks in winter and decreasing of production of grass communities in dry years. Based on pasture forage stocks the area could tolerate the maximum population size of 1769 individuals of the Przewalski horse, their average density could be 0.11 horse per ha. Yet, as watering places for animals are limited in Pre-Urals Steppe, grazing pressures on the vegetation next to the water sources may increase in dry years. That is why the above-mentioned calculated maximum population size and density must be reduced at least by half until some additional watering places are established and monitoring of the grazing effect on the vegetation next to the places is carried out regularly. Thus, the maximum size of the population is estimated at 800 to 900 individuals, which is almost 1.5 times more than necessary to establish a self-sustained population of the Przewalski horse.

The use of less common grass varieties as a factor of increasing forage lands productivity

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В. Д. Бугайов

2017-03-01

Full Text Available Purpose. To assess introduced samples of drought-resistant species of perennial grasses, select a promising parent material and create on its base high-yielding varie­ ies with economic characters. Methods. Field experiment, laboratory testing. Results. The results of studies on introduction and breeding were given aimed to improve drought tolerance of non-traditional perennial grasses under the conditions of the Right-Bank Forest-Steppe zone of Ukraine. Based on the selected parent material, varieties were created by the use of hybridization and ecotype breeding methods and then entered into the State Register of plant varieties suitable for dissemination in Ukraine, among them: intermediate wheatgrass (Elytrigia intermedia (Host Nevski – ‘Hors’, crested wheatgrass (Agropyron cristatum (L. Gaertn. – ‘Petrivskyi’; meadow brome (Bromus riparia Rehm. – ‘Boian’; slender wheatgrass (Roegneria trachycaulon (Link Nevski – ‘Co­umb’. As compared with conventional, relatively drought-tolerant species of smooth brome (Bromopsis inermis (Leyss. Holub – ‘Mars’, increment of dry matter content of these species in the extreme drought conditions of 2011 was increased by 1,52–3,73 t/ha. Under more sufficient moistening conditions of 2012, slender wheatgrass ‘Columb’ was at the level of the сheck variety in terms of this indicator. Other varieties exceeded it by 1.44–3.22 t/ha. The data was given including seed productivity and sowing quality indicators, after-ripening duration and economic fitness of seeds. Conclusions. The use of the recommended varieties of drought-resistant species of perennial grasses as part of grass mixtures will increase significantly the productivity of grasslands and pastures in the current context of climate change.

On the Succession of Sarmatian Population in the East-European Steppes

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Balabanova Mariya A.

2016-06-01

Full Text Available As V.P. Alekseev wrote, the succession of population has been peculiar for individual territories for centuries. Despite the fact that the Eastern European steppe in ancient times and the Middle Ages was characterized by frequent changes of the population due to its high dependence on the environmental conditions, the Sarmatian culture preservation was observed over a period of ceremonial standards and elements of material culture. In this paper an attempt is made to show the presence of a partial succession of the three chronological periods of Sarmatian population. To do this, the author conducted a comparative characteristic of physical types of nomads of Sarmatian steppes of the Eastern Europe. The results of the study of mass craniological material combined in the cultural and chronological groups, showed that on the whole range of time and space over the steppe habitat Sarmatian cultures fixed partial similarity in physical type. In this connection, it is assumed that the partial continuity of anthropological types of different cultural, historical and local groups is linked to: 1 partial preservation of substrate Early Sarmatian population over the 4th- 3rd centuries BC – first half of 2nd-4th centuries AD; 2 the direction and character of penetration of nomadic groups who migrated from the East into steppe space; 3 design of a single system of seasonal migrations which involves the presence of winter and summer camps, and the presence of burial mounds; 4 the inclusion of a horde of nomadic pastoral population groups moved all over the steppes, from between Volga and Ural to the Lower Don; 5 the fact that male migrants married local women.

Do changes in grazing pressure and the degree of shrub encroachment alter the effects of individual shrubs on understorey plant communities and soil function?

Science.gov (United States)

Soliveres, Santiago; Eldridge, David J

2014-04-01

Shrub canopies in semi-arid environments often produce positive effects on soil fertility, and on the richness and biomass of understorey plant communities. However, both positive and negative effects of shrub encroachment on plant and soil attributes have been reported at the landscape-level. The contrasting results between patch- and landscape-level effects in shrublands could be caused by differences in the degree of shrub encroachment or grazing pressure, both of which are likely to reduce the ability of individual shrubs to ameliorate their understorey environment.We examined how grazing and shrub encroachment (measured as landscape-level shrub cover) influence patch-level effects of shrubs on plant density, biomass and similarity in species composition between shrub understories and open areas, and on soil stability, nutrient cycling, and infiltration in two semi-arid Australian woodlands.Individual shrubs had consistently positive effects on all plant and soil variables (average increase of 23% for all variables). These positive patch-level effects persisted with increasing shrub cover up to our maximum of 50% cover. Heavy grazing negatively affected most of the variables studied (average decline of 11%). It also altered, for some variables, how individual shrubs affected their sub-canopy environment with increasing shrub cover. Thus for species density, biomass and soil infiltration, the positive effect of individual shrubs with increasing shrub cover diminished under heavy grazing. Our study refines predictions of the effects of woody encroachment on ecosystem structure and functioning by showing that heavy grazing, rather than differences in shrub cover, explains the contrasting effects on ecosystem structure and function between individual shrubs and those in dense aggregations. We also discuss how species-specific traits of the encroaching species, such as their height or its ability to fix N, might influence the relationship between their patch

Permafrost response to increasing Arctic shrub abundance depends on the relative influence of shrubs on local soil cooling versus large-scale climate warming

International Nuclear Information System (INIS)

Lawrence, David M; Swenson, Sean C

2011-01-01

Deciduous shrub abundance is increasing across the Arctic in response to climatic warming. In a recent field manipulation experiment in which shrubs were removed from a plot and compared to a control plot with shrubs, Blok et al (2010 Glob. Change Biol. 16 1296–305) found that shrubs protect the ground through shading, resulting in a ∼ 9% shallower active layer thickness (ALT) under shrubs compared to grassy-tundra, which led them to argue that continued Arctic shrub expansion could mitigate future permafrost thaw. We utilize the Community Land Model (CLM4) coupled to the Community Atmosphere Model (CAM4) to evaluate this hypothesis. CLM4 simulates shallower ALT (∼− 11 cm) under shrubs, consistent with the field manipulation study. However, in an idealized pan-Arctic + 20% shrub area experiment, atmospheric heating, driven mainly by surface albedo changes related to protrusion of shrub stems above the spring snowpack, leads to soil warming and deeper ALT (∼+ 10 cm). Therefore, if climate feedbacks are considered, shrub expansion may actually increase rather than decrease permafrost vulnerability. When we account for blowing-snow redistribution from grassy-tundra to shrubs, shifts in snowpack distribution in low versus high shrub area simulations counter the climate warming impact, resulting in a grid cell mean ALT that is unchanged. These results reinforce the need to consider vegetation dynamics and blowing-snow processes in the permafrost thaw model projections.

Gender-related traits in the dioecious shrub Empetrum rubrum in two plant communities in the Magellanic steppe

Science.gov (United States)

Díaz-Barradas, Mari Cruz; Zunzunegui, María; Collantes, Marta; Álvarez-Cansino, Leonor; García Novo, Francisco

2014-10-01

Following the theory on costs of reproduction, sexually dimorphic plants may exhibit several trade-offs in energy and resources that can determine gender dimorphism in morphological or physiological traits, especially during the reproductive period. In this study we assess whether the sexes of the dioecious species Empetrum rubrum differ in morphological and ecophysiological traits related to water economy and photochemical efficiency and whether these differences change in nearby populations with contrasting plant communities. We conducted physiological, morphological, sex ratio, and cover measurements in E. rubrum plants in the Magellanic steppe, North-Eastern part of Tierra del Fuego (Argentina), from two types of heathlands with differing community composition. We found differences between sites in soil pH and wind speed at the canopy level. E. rubrum plants exhibited lower photosynthetic height and higher LAI (leaf area index), lower RWC (relative water content) and higher water-use efficiency (lower Δ13C) in the heathland with harsher environmental conditions. Gender dimorphism in the physiological response was patent for photochemical efficiency and water use (RWC and Δ13C discrimination), with males showing a more conservative strategy in relation to females. Accordingly, male-biased sex ratio in the stress-prone community suggested a better performance of male plants under stressful environmental conditions. The integrated analysis of all variables (photochemical efficiency, RWC, leaf dry matter content (LDMC), pigments, and Δ13C) indicated an interaction between gender and heathland community effects in the physiological response. We suggest that female plants may exhibit compensatory mechanisms to face their higher reproductive costs.

Seedling responses to water pulses in shrubs with contrasting histories of grassland encroachment.

Directory of Open Access Journals (Sweden)

Steven R Woods

Full Text Available Woody plant encroachment into grasslands has occurred worldwide, but it is unclear why some tree and shrub species have been markedly more successful than others. For example, Prosopis velutina has proliferated in many grasslands of the Sonoran Desert in North America over the past century, while other shrub species with similar growth form and life history, such as Acacia greggii, have not. We conducted a glasshouse experiment to assess whether differences in early seedling development could help explain why one species and not the other came to dominate many Sonoran Desert grasslands. We established eight watering treatments mimicking a range of natural precipitation patterns and harvested seedlings 16 or 17 days after germination. A. greggii had nearly 7 times more seed mass than P. velutina, but P. velutina emerged earlier (by 3.0±0.3 d and grew faster (by 8.7±0.5 mg d⁻¹. Shoot mass at harvest was higher in A. greggii (99±6 mg seedling⁻¹ than in P. velutina (74±2 mg seedling⁻¹, but there was no significant difference in root mass (54±3 and 49±2 mg seedling⁻¹, respectively. Taproot elongation was differentially sensitive to water supply: under the highest initial watering pulse, taproots were 52±19 mm longer in P. velutina than in A. greggii. Enhanced taproot elongation under favorable rainfall conditions could give nascent P. velutina seedlings growth and survivorship advantages by helping reduce competition with grasses and maintain contact with soil water during drought. Conversely, A. greggii's greater investment in mass per seed appeared to provide little return in early seedling growth. We suggest that such differences in recruitment traits and their sensitivities to environmental conditions may help explain ecological differences between species that are highly similar as adults and help identify pivotal drivers of shrub encroachment into grasslands.

Eurasian perspectives on the role of kurgans in the conservation and restoration of steppe vegetation

Science.gov (United States)

Deák, Balázs; Valkó, Orsolya; Török, Péter; Sudnik-Wójcikowska, Barbara; Moysiyenko, Ivan; Bragina, Tatyana; Apostolova, Iva; Dembicz, Iwona; Bykov, Nikolai; Tóthmérész, Béla

2017-04-01

Steppe is among the most endangered biomes of the world, especially in Europe, where more than 90% of original steppes have been destroyed due to conversion into croplands, afforestation and other human activities. Because of the socio-economic changes of the past centuries, steppe vegetation is now often restricted to places inadequate for ploughing, such as ancient burial mounds called kurgans. Thus, beside that kurgans are millennia-old iconic historical monuments of the steppic landscape, they are vital in preserving both our cultural and natural heritage. We collected and synthesised existing knowledge on kurgans by a review of research papers and grey literature and provided recommendations for elaborating the involvement of kurgans into agri-environmental schemes. We found that the proportions of kurgans covered by steppe vegetation increase from west to east and from lowlands to uplands. Despite their small size, kurgans act as biodiversity hotspots and harbour many red-listed plant species. High biodiversity is maintained by a pronounced fine-scale environmental heterogeneity provided by the special micro-topography of the kurgans. We found that landscape-level land use changes such as intensified agriculture and construction works are the major threatening factors for biodiversity of kurgans. Despite the vital role of kurgans in sustaining steppe vegetation, we identified serious knowledge gaps on their distribution, vegetation, flora and fauna and their potential role in steppe restoration. We conclude that these sacral places play a crucial role in preserving steppe vegetation, especially in intensively used agricultural landscapes in the western part of the steppe zone. They maintain ecosystem functions at the landscape-level by providing refugia for rare grassland specialist species and ensuring habitat connectivity in anthropogenic landscapes. Based on our results we suggest improving existing agri-environmental schemes which only focus on the

Global grass (Poaceae) success underpinned by traits facilitating colonization, persistence and habitat transformation.

Science.gov (United States)

Linder, H P; Lehmann, Caroline E R; Archibald, Sally; Osborne, Colin P; Richardson, David M

2018-05-01

, fostering high biomass and diversity of mammalian herbivores. Many grasses have a suite of architectural and functional traits that facilitate frequent fire, including a tufted growth form, and tannin-like substances in leaves which slow decomposition. We mapped these traits over the phylogeny of the Poales, spanning the grasses and their relatives, and demonstrated the accumulation of traits since monocots originated in the mid-Cretaceous. Although the sympodial growth form is a monocot trait, tillering resulting in the tufted growth form most likely evolved within the grasses. Similarly, although an ovary apparently constructed of a single carpel evolved in the most recent grass ancestor, spikelets and the awned lemma dispersal units evolved within the grasses. Frost tolerance and C 4 photosynthesis evolved relatively late (late Palaeogene), and the last significant trait to evolve was probably the production of tannins, associated with pyrophytic savannas. This fits palaeobotanical data, suggesting several phases in the grass success story: from a late Cretaceous origin, to occasional tropical grassland patches in the later Palaeogene, to extensive C 3 grassy woodlands in the early-middle Miocene, to the dramatic expansion of the tropical C 4 grass savannas and grasslands in the Pliocene, and the C 3 steppe grasslands during the Pleistocene glacial periods. Modern grasslands depend heavily on strongly seasonal climates, making them sensitive to climate change. © 2017 Cambridge Philosophical Society.

Improved quality of beneath-canopy grass in South African savannas: Local and seasonal variation

NARCIS (Netherlands)

Treydte, A.C.; Looringh van Beeck, F.A.; Ludwig, F.; Heitkonig, I.M.A.

2008-01-01

Questions: Do large trees improve the nutrient content and the structure of the grass layer in savannas? Does the magnitude of this improvement differ with locality ( soil nutrients) and season ( water availability)? Are grass structure and species composition beneath tree canopies influenced by

Competition for phosphorus: differential uptake from dual-isotope-labeled soil interspaces between shrub and grass

International Nuclear Information System (INIS)

Caldwell, M.M.; Eissenstat, D.M.; Richards, J.H.; Allen, M.F.

1985-01-01

Two species of Agropyron grass differed strikingly in their capacity to compete for phosphate in soil interspaces shared with a common competitor, the sagebrush Artemisia tridentata. Of the total phosphorus-32 and -33 absorbed by Artemisia, 86% was from the interspace shared with Agropyron spicatum and only 14% from that shared with Agropyron desertorum. Actively absorbing mycorrhizal roots of Agropyron and Artemisia were present in both interspaces, where competition for the labeled phosphate occurred. The results have important implications about the way in which plants compete for resources below ground in both natural plant communities and agricultural intercropping systems

Stem secondary growth of tundra shrubs

DEFF Research Database (Denmark)

Campioli, Matteo; Leblans, Niki; Michelsen, Anders

2012-01-01

Our knowledge of stem secondary growth of arctic shrubs (a key component of tundra net primary production, NPP) is very limited. Here, we investigated the impact of the physical elements of the environment on shrub secondary growth by comparing annual growth rates of model species from similar...... growth (stem apical growth, stem length, and apical growth of stem plus leaves), in some cases even with opposite responses. Thus caution should be taken when estimating the impact of the environment on shrub growth from apical growth only. Integration of our data set with the (very limited) previously...

Identification, Classification, Mapping of Model and Secondary Steppe Ecosystems Within the Orenburg-Kazakhstan Cross-Border Region

Directory of Open Access Journals (Sweden)

Yakovlev Ilya Gennadyevich

2014-09-01

Full Text Available The article deals with the current issues of modern steppe management in the Orenburg-Kazakhstan cross-border region. The authors use the data of their own field research over the period of 2009-2014 aimed at detection and classification of model and secondary steppe ecosystems in the region. For the last 6 years it has been revealed that some steppe and fallow lands have different squares. The detected lands are multiple-aged and differ according to their qualitative composition depending on aged-specific (time for completion of agricultural activity, soil-lithogenous and floristic features.The authors detected sites of anthropogenic influence on steppe ecosystems as well as the factors that have favorable affect on restoration of natural ecosystems. The article also reveals the centers of restoration of traditional steppe fauna within the Orenburg-Kazakhstan region and the distribution area of marmot, little bustard, bustard, saiga antelope. The authors carried out the comparative analysis of agro-ecological situation in the region for a few last years as well as over long period of time according to archival and polling data.

Comparative nutritional ecology of grass-feeding in a sub-Antarctic beetle: the impact of introduced species on Hydromedion sparsutum from South Georgia.

Science.gov (United States)

Chown, S L; Block, W

1997-07-01

South Georgia has many introduced plant and animal species, a consequence of its long history of human habitation. Introduced reindeer have a strong effect on the vegetation of the Stromness Bay area by causing the replacement of indigenous species by grazing-tolerant grasses such as the exotic Poa annua, and in certain circumstances, the indigenous Festuca contracta. Recently it has been argued that an introduced predatory carabid has contributed to declines in the abundance and an increase in the body size of adults of the indigenous perimylopid beetle Hydromedion sparsutum. However, it also appears that body size of these beetles is smaller in areas where exotic grasses predominate compared to undisturbed areas. Here we test the hypothesis that by causing the spread of poorer quality grasses, especially the exotic Poa annua, reindeer may be having an indirect effect on H. sparsutum. To do this we examined the nutritional ecology of H. sparsutum larvae on four grass species which form a major part of its diet, viz. the indigenous Parodiochloa flabellata, Phleum alpinum and Festuca contracta, and the exotic Poa annua. Larvae showed the highest growth rate on Parodiochloa flabellata, followed by Phleum alpinum, F. contracta and Poa annua. These differences are due to poorer absorption of the exotic grass, and poorer utilization of the absorbed material in the case of F. contracta. Poor growth of larvae on F. contracta appears to be due to its low water and nitrogen contents, whereas in the case of P. annua a combination of low water content and high nitrogen content may be responsible for low growth rates. Low growth rates associated with poor-quality food may lead either to a prolongation of the life cycle or of the length of feeding bouts of an insect. Neither option appears to be feasible for H. sparsutum, and this means that the outcome of feeding on poorer-quality foods would be a reduction in final adult size. This has fitness consequences for the beetle

The changing role of shrubs in rangeland-based livestock production systems: Can shrubs increase our forage supply?

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Projected global increases in ruminant numbers and loss of native grasslands will present a number of challenges for livestock agriculture. Escalated demand for livestock products may stimulate interest in using shrubs on western rangelands. A paradigm shift is needed to change the role of shrubs in...

Relationships between Arctic shrub dynamics and topographically derived hydrologic characteristics

International Nuclear Information System (INIS)

Naito, Adam T; Cairns, David M

2011-01-01

Shrub expansion is a global phenomenon that is gaining increased attention in the Arctic. Recent work employing the use of oblique aerial photographs suggested a consistent pattern of positive change in shrub cover across the North Slope of Alaska. The greatest amounts of change occurred in valley slopes and floodplains. We studied the association between shrub cover change and topographically derived hydrologic characteristics in five areas in northern Alaska between the 1970s and 2000s. Change in total shrub cover ranged from − 0.65% to 46.56%. Change in floodplain shrub cover ranged from 3.38% to 76.22%. Shrubs are preferentially expanding into areas of higher topographic wetness index (TWI) values where the potential for moisture accumulation or drainage is greater. In addition, we found that floodplain shrub development was strongly associated with high TWI values and a decreasing average distance between shrubs and the river bank. This suggests an interacting influence of substrate removal and stabilization as a consequence of increased vegetation cover.

Climate sensitivity of shrub growth across the tundra biome

DEFF Research Database (Denmark)

Myers-Smith, Isla H.; Elmendorf, Sarah C.; Beck, Pieter S.A.

2015-01-01

Rapid climate warming in the tundra biome has been linked to increasing shrub dominance1–4. Shrub expansion can modify climate by altering surface albedo, energy and water balance, and permafrost2,5–8, yet the drivers of shrub growth remain poorly understood. Dendroecological data consisting...... of multi-decadal time series of annual shrub growth provide an underused resource to explore climate–growth relationships. Here, we analyse circumpolar data from 37 Arctic and alpine sites in 9 countries, including 25 species, and 42,000 annual growth records from 1,821 individuals. Our analyses...... demonstrate that the sensitivity of shrub growth to climate was: (1) heterogeneous, with European sites showing greater summer temperature sensitivity than North American sites, and (2) higher at sites with greater soil moisture and for taller shrubs (for example, alders and willows) growing at their northern...

Grazing effects on ecosystem CO2 fluxes differ among temperate steppe types in Eurasia.

Science.gov (United States)

Hou, Longyu; Liu, Yan; Du, Jiancai; Wang, Mingya; Wang, Hui; Mao, Peisheng

2016-07-01

Grassland ecosystems play a critical role in regulating CO2 fluxes into and out of the Earth's surface. Whereas previous studies have often addressed single fluxes of CO2 separately, few have addressed the relation among and controls of multiple CO2 sub-fluxes simultaneously. In this study, we examined the relation among and controls of individual CO2 fluxes (i.e., GEP, NEP, SR, ER, CR) in three contrasting temperate steppes of north China, as affected by livestock grazing. Our findings show that climatic controls of the seasonal patterns in CO2 fluxes were both individual flux- and steppe type-specific, with significant grazing impacts observed for canopy respiration only. In contrast, climatic controls of the annual patterns were only individual flux-specific, with minor grazing impacts on the individual fluxes. Grazing significantly reduced the mean annual soil respiration rate in the typical and desert steppes, but significantly enhanced both soil and canopy respiration in the meadow steppe. Our study suggests that a reassessment of the role of livestock grazing in regulating GHG exchanges is imperative in future studies.

Irrigation of steppe soils in the south of Russia: Problems and solutions (Analysis of Irrigation Practices in 1950-1990)

Science.gov (United States)

Minashina, N. G.

2009-07-01

Experience in irrigation of chernozems in the steppe zone of Russia for a period from 1950 to 1990 is analyzed. By the end of this period and in the subsequent years, the areas under irrigation reduced considerably, and the soil productivity worsened. This was caused by the improper design of irrigation systems, on the one hand, and by the low tolerance of chernozems toward increased moistening upon irrigation, on the other hand. The analysis of the factors and regimes of soil formation under irrigation conditions shows that irrigation-induced changes in the soil hydrology also lead to changes in the soil physicochemical, biochemical, and other properties. In particular, changes in the composition of exchangeable cations lead to the development of solonetzic process. In many areas, irrigation of chernozems was accompanied by the appearance of solonetzic, vertic, saline, and eroded soils. The development of soil degradation processes is described. In general, the deterioration of irrigated chernozems was related to the absence of adequate experience in irrigation of steppe soils, unskilled personnel, improper regime of irrigation, and excessively high rates of watering. In some cases, the poor quality of irrigation water resulted in the development of soil salinization and alkalization. To improve the situation, the training of personnel is necessary; the strategy of continuous irrigation should be replaced by the strategy of supplementary irrigation in the critical periods of crop development.

A network of the steppe and forest steppe along the Prut and Lower Danube rivers during the 6th millennium BC

Directory of Open Access Journals (Sweden)

Agathe Reingruber

2016-12-01

Full Text Available The transition from a (predominantly mobile way of life relying on hunting, fishing and gathering to a (predominantly sedentary life-style based on farming and animal husbandry is considered in the western Pontic archaeological tradition almost exclusively from a southern, AegeanAnatolian perspective. Contacts between the steppe and forest steppe of the north-eastern Balkans and the north-western Pontic were seen as linear and unidirectional; ‘cultures’ were defined almost exclusively on the basis of pottery styles. Not only such traditional viewpoints, but also the political conditions of the 20th century further biased prehistoric research. However, the outer Carpathian region should not be treated as a periphery of the inner Carpathian Cris culture, but as a region of multidirectional exchange networks. Moreover, certain traditions are obviously rooted in the Mesolithic of that area.

Shrub expansion in SW Greenland

DEFF Research Database (Denmark)

Jørgensen, Rasmus Halfdan

Arctic regions have experienced higher temperatures in recent decades, and the warming trend is projected to continue in the coming years. Arctic ecosystems are considered to be particularly vulnerable to climate change. Expansion of shrubs has been observed widely in tundra areas across the Arctic......, and has a range of ecosystem effects where it occurs. Shrub expansion has to a large extend been attributed to increasing temperatures over the past century, while grazing and human disturbance have received less attention. Alnus viridis ssp. crispa is a common arctic species that contributes...... to increasing shrub cover. Despite this, there is only limited experimental evidence that growth of the species responds to warming. Plant populations in fragmented and isolated locations could face problems adapting to a warming climate due to limited genetic variation and restricted migration from southern...

Modeling of the evolution of steppe chernozems and development of the method of pedogenetic chronology

DEFF Research Database (Denmark)

Lisetskii, F.N.; Stolba, Vladimir; Goleusov, P.V.

2016-01-01

Geoarchaeological methods were used to study chronosequences of surface soils in the steppe zone and to trace soil evolution during the Late Holocene in northwestern Crimea. It was found that the morphological and functional “maturity” of the humus horizons in steppe chernozems of the Late Holocene...

Holocene vegetation dynamics of Taiga forest in the Southern Altai Mountains documented by sediments from Kanas Lake

Science.gov (United States)

Huang, X.; Chen, F.

2016-12-01

The Chinese Altai is the southern limit of the Taiga forest of the continent, and regional vegetation dynamics during the Holocene will help us to understand regional climate changes, such as the Siberian High variations. Here we present a pollen-based vegetation and climate reconstruction from a well dated sediment core from Kanas Lake, a deep glacial moraine dammed lake in the Southern Altai Mountains (Chinese Altai). The 244-cm-long sequence spans the last 13,500 years, and the chronology is based on nine accelerator mass spectrometry radiocarbon dates from terrestrial plant macrofossils. At least five stages of regional vegetation history are documented: (i) From 13.5 to 11.7 ka (1 ka = 1000 cal yr BP), Kanas Lake region was occupied by steppe dominated by Artemisia, Chenopodiaceae and grass pollen, with low tree coverage. (ii) From 11.7 to 8.5 ka, regional forest build up dramatically indicated by increasing tree pollen percentages, including Picea, Larix, and the highest Junipers, with decreasing Artemisia and increasing Chenopodiaceae. (iii) From 8.5 to 7.2 ka, the forest around the lake became dense with the maximum content of Picea and Betula pollen types. And the steppe pollen types reached their lowest values. (iv) From 7.2 to 4 ka, as a typical tree species of Taiga forest, Larix pollen percentage became much higher than previous stage, and the sum of trees & shrubs pollen types decreased, which possibly indicated cooler and wetter climate (v) After 4 ka, trees & shrubs (e.g. Betula, Junipers) pollen types decreased, with increasing Artemisia and decreasing Chenopodiaceae, which might indicated more humid and cooler climate in the late Holocene. Comparing to the other pollen records in the Altai Mountains, Lake Grusha and Lake Hoton had recorded a slightly different process of vegetation evolution in the early Holocene, where forest was built up in the northern side of the Chinese Altai faster than that of the Kanas Lake area. And the difference could

resistance of napier grass clones to napier grass stunt disease

African Journals Online (AJOL)

ACSS

Napier grass (Pennisetum purpureum Schumach) is the major livestock fodder under intensive and semi-intensive systems in East Africa. However, the productivity of the grass is constrained by Napier grass Stunt Disease. (NSD). The purpose of this study was to identify Napier grass clones with resistance to NSD.

Resistance of Napier grass clones to Napier grass Stunt Disease ...

African Journals Online (AJOL)

Napier grass (Pennisetum purpureum Schumach) is the major livestock fodder under intensive and semi-intensive systems in East Africa. However, the productivity of the grass is constrained by Napier grass Stunt Disease (NSD). The purpose of this study was to identify Napier grass clones with resistance to NSD.

Deglacial palaeoclimate at Puerto del Hambre, subantarctic Patagonia, Chile

Science.gov (United States)

Heusser, Calvin J.; Heusser, Linda E.; Lowell, Thomas V.; Moreira M., Andrés; Moreira M., Simón

2000-02-01

The primary objective of this study is to further substantiate multistep climatic forcing of late-glacial vegetation in southern South America. A secondary objective is to establish the age of deglaciation in Estrecho de Magallanes-Bahía Inútil. Pollen assemblages at 2-cm intervals in a core of the mire at Puerto del Hambre (53°3621S, 70°5553W) provide the basis for reconstructing the vegetation and a detailed account of palaeoclimate in subantarctic Patagonia. Chronology over the 262-cm length of core is regulated by 20 AMS radiocarbon dates between 14 455 and 10 089 14C yr BP. Of 13 pollen assemblage zones, the earliest representing the Oldest Dryas chronozone (14 455-13 000 14C yr BP) records impoverished steppe with decreasing frequencies and loss of southern beech (Nothofagus). Successive 100-yr-long episodes of grass/herbs and of heath (Empetrum/Ericaceae) before 14 000 14C yr BP infer deglacial successional communities under a climate of increased continentality prior to the establishment of grass-dominated steppe. The Bølling-Allerød (13 000-11 000 14C yr BP) is characterised by mesic grassland under moderating climate that with abrupt change to heath dominance after 12 000 14C yr BP was warmer and not as humid. At the time of the Younger Dryas (11 000-10 000 14C yr BP), grass steppe expanded with a return of colder, more humid climate. Later, with gradual warming, communities were invaded by southern beech. The Puerto del Hambre record parallels multistep, deglacial palaeoclimatic sequences reported elsewhere in the Southern Andes and at Taylor Dome in Antarctica. Deglaciation of Estrecho de Magallanes-Bahía Inútil is dated close to 14 455 14C yr BP, invalidating earlier dates of between 15 800 and 16 590 14C yr BP.

Managed grassland alters soil N dynamics and N2O emissions in temperate steppe.

Science.gov (United States)

Xu, Lijun; Xu, Xingliang; Tang, Xuejuan; Xin, Xiaoping; Ye, Liming; Yang, Guixia; Tang, Huajun; Lv, Shijie; Xu, Dawei; Zhang, Zhao

2018-04-01

Reclamation of degraded grasslands as managed grasslands has been increasingly accelerated in recent years in China. Land use change affects soil nitrogen (N) dynamics and nitrous oxide (N 2 O) emissions. However, it remains unclear how large-scale grassland reclamation will impact the grassland ecosystem as a whole. Here, we investigated the effects of the conversion from native to managed grasslands on soil N dynamics and N2O emissions by field experiments in Hulunber in northern China. Soil (0-10cm), nitrate (NO 3 - ), ammonium (NH 4 + ), and microbial N were measured in plots in a temperate steppe (Leymus chinensis grassland) and two managed grasslands (Medicago sativa and Bromus inermis grasslands) in 2011 and 2012. The results showed conversion of L. chinensis grassland to M. sativa or B. inermis grasslands decreased concentrations of NO 3 - -N, but did not change NH 4 + -N. Soil microbial N was slightly decreased by the conversion of L. chinensis grassland to M. sativa, but increased by the conversion to B. inermis. The conversion of L. chinensis grassland to M. sativa (i.e., a legume grass) increased N 2 O emissions by 26.2%, while the conversion to the B. inermis (i.e., a non-legume grass) reduced N 2 O emissions by 33.1%. The conversion from native to managed grasslands caused large created variations in soil NO 3 - -N and NH 4 + -N concentrations. Net N mineralization rates did not change significantly in growing season or vegetation type, but to net nitrification rate. These results provide evidence on how reclamation may impact the grassland ecosystem in terms of N dynamics and N 2 O emissions. Copyright © 2017. Published by Elsevier B.V.

Critical responses of photosynthetic efficiency in Campsis radicans ...

African Journals Online (AJOL)

use

and annual accumulated temperature over 10°C is 2750°C The soil is classified as brown and cinnamon soil, with inferior development and severe water and soil erosion. The vegetation type is forest- steppe and shrub zones with little shrub species and most of woodland is open forest with low stability. Jiang-bao et al.

Effects of Prescribed Burning on Grazed Shortgrass Steppe

Science.gov (United States)

Over the past century, fire has been widely suppressed in the western Great Plains, in part due to potential negative effects on forage production for livestock. Interest in the use of prescribed fire in shortgrass steppe has increased recently due to applications for wildlife management, control of...

Changing Climate and Overgrazing Are Decimating Mongolian Steppes

KAUST Repository

Liu, Yi Y.; Evans, Jason P.; McCabe, Matthew; de Jeu, Richard A. M.; van Dijk, Albert I. J. M.; Dolman, Albertus J.; Saizen, Izuru

2013-01-01

Satellite observations identify the Mongolian steppes as a hotspot of global biomass reduction, the extent of which is comparable with tropical rainforest deforestation. To conserve or restore these grasslands, the relative contributions of climate and human activities to degradation need to be understood. Here we use a recently developed 21-year (1988-2008) record of satellite based vegetation optical depth (VOD, a proxy for vegetation water content and aboveground biomass), to show that nearly all steppe grasslands in Mongolia experienced significant decreases in VOD. Approximately 60% of the VOD declines can be directly explained by variations in rainfall and surface temperature. After removing these climate induced influences, a significant decreasing trend still persists in the VOD residuals across regions of Mongolia. Correlations in spatial patterns and temporal trends suggest that a marked increase in goat density with associated grazing pressures and wild fires are the most likely non-climatic factors behind grassland degradation. © 2013 Liu et al.

Changing climate and overgrazing are decimating Mongolian steppes.

Directory of Open Access Journals (Sweden)

Yi Y Liu

Full Text Available Satellite observations identify the Mongolian steppes as a hotspot of global biomass reduction, the extent of which is comparable with tropical rainforest deforestation. To conserve or restore these grasslands, the relative contributions of climate and human activities to degradation need to be understood. Here we use a recently developed 21-year (1988-2008 record of satellite based vegetation optical depth (VOD, a proxy for vegetation water content and aboveground biomass, to show that nearly all steppe grasslands in Mongolia experienced significant decreases in VOD. Approximately 60% of the VOD declines can be directly explained by variations in rainfall and surface temperature. After removing these climate induced influences, a significant decreasing trend still persists in the VOD residuals across regions of Mongolia. Correlations in spatial patterns and temporal trends suggest that a marked increase in goat density with associated grazing pressures and wild fires are the most likely non-climatic factors behind grassland degradation.

Changing Climate and Overgrazing Are Decimating Mongolian Steppes

KAUST Repository

Liu, Yi Y.

2013-02-25

Satellite observations identify the Mongolian steppes as a hotspot of global biomass reduction, the extent of which is comparable with tropical rainforest deforestation. To conserve or restore these grasslands, the relative contributions of climate and human activities to degradation need to be understood. Here we use a recently developed 21-year (1988-2008) record of satellite based vegetation optical depth (VOD, a proxy for vegetation water content and aboveground biomass), to show that nearly all steppe grasslands in Mongolia experienced significant decreases in VOD. Approximately 60% of the VOD declines can be directly explained by variations in rainfall and surface temperature. After removing these climate induced influences, a significant decreasing trend still persists in the VOD residuals across regions of Mongolia. Correlations in spatial patterns and temporal trends suggest that a marked increase in goat density with associated grazing pressures and wild fires are the most likely non-climatic factors behind grassland degradation. © 2013 Liu et al.

Possibility of Morphometrical Determining of Sex of Steppe Eagle Nestlings from Western and Eastern Populations?

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Igor V. Karyakin

2018-03-01

Full Text Available Sexual dimorphism among nestlings of the Steppe Eagle (Aquila nipalensis is poorly manifested. Thus, determining of sex by morphometric methods encountered many difficulties and could be completed only by the most experienced ornithologists who knows the species very well. This article presents a morphometric method for determining sex of nestlings of the Steppe Eagles from different breeding populations that belongs to different size classes. The method is based on classification formula obtained via linear discriminant analysis conducted for the data set of measurements of Steppe Eagle’s nestlings from Central Kazakhstan and Altai Republic in 2017. To control the sex determination of nestlings a molecular-genetics method was used.

Detection of damaged areas caused by the oil extraction in a steppe region using winter landsat imagery

Science.gov (United States)

Mjachina, Ksenya; Hu, Zhiyong; Chibilyev, Alexander

2018-01-01

Oil production in a steppe region disturbs the landscape and damages the steppe ecosystem. The objective of this research was to detect areas damaged by oil production in an oil field within the Russian Volga-Ural steppe region using winter Landsat imagery. We developed a practicable and effective approach using winter snow season multispectral Landsat satellite imagery. To this end, we applied seven algorithms of spectral or texture-based transformation: K-means, maximum likelihood estimation, topsoil grain size index, soil brightness, normalized differential snow index, tasselled cap, and co-occurrence measures. The co-occurrence texture measure variance shows the optimal result of identifying damaged areas. The unique feature of our method is that it can differentiate damaged areas from the bare soil of cropland within a cold steppe region where the area damaged by oil production is mixed with bare (fallow) croplands that have a polygonal shape similar to well pads. Such similarities can lead to confusion in object-based classification. Using the co-occurrence measures, we found that from 1988 to 2015, damaged area is nearly three times as big in the peak period of the oil field development (2001 and 2009) as in 1988. Landscape fragmentation also peaked in 2001 and 2009. Our approach for this project is useful and cost effective regular monitoring of damages from oil production for both the Volga-Ural steppe region and other cold steppe regions.

Ancestry and demography and descendants of Iron Age nomads of the Eurasian Steppe

Science.gov (United States)

Unterländer, Martina; Palstra, Friso; Lazaridis, Iosif; Pilipenko, Aleksandr; Hofmanová, Zuzana; Groß, Melanie; Sell, Christian; Blöcher, Jens; Kirsanow, Karola; Rohland, Nadin; Rieger, Benjamin; Kaiser, Elke; Schier, Wolfram; Pozdniakov, Dimitri; Khokhlov, Aleksandr; Georges, Myriam; Wilde, Sandra; Powell, Adam; Heyer, Evelyne; Currat, Mathias; Reich, David; Samashev, Zainolla; Parzinger, Hermann; Molodin, Vyacheslav I.; Burger, Joachim

2017-03-01

During the 1st millennium before the Common Era (BCE), nomadic tribes associated with the Iron Age Scythian culture spread over the Eurasian Steppe, covering a territory of more than 3,500 km in breadth. To understand the demographic processes behind the spread of the Scythian culture, we analysed genomic data from eight individuals and a mitochondrial dataset of 96 individuals originating in eastern and western parts of the Eurasian Steppe. Genomic inference reveals that Scythians in the east and the west of the steppe zone can best be described as a mixture of Yamnaya-related ancestry and an East Asian component. Demographic modelling suggests independent origins for eastern and western groups with ongoing gene-flow between them, plausibly explaining the striking uniformity of their material culture. We also find evidence that significant gene-flow from east to west Eurasia must have occurred early during the Iron Age.

Restoration handbook for sagebrush steppe ecosystems with emphasis on greater sage-grouse habitat - Part 1

Science.gov (United States)

David A. Pyke; Jeanne C. Chambers; Mike Pellant; Steven T. Knick; Richard F. Miller; Jeffrey L. Beck; Paul S. Doescher; Eugene W. Schupp; Bruce A. Roundy; Mark Brunson; James D. McIver

2015-01-01

Sagebrush steppe ecosystems in the United States currently occur on only about one-half of their historical land area because of changes in land use, urban growth, and degradation of land, including invasions of non-native plants. The existence of many animal species depends on the existence of sagebrush steppe habitat. The greater sage-grouse (Centrocercus...

Temperate heath plant response to dry conditions depends on growth strategy and less on physiology

DEFF Research Database (Denmark)

Albert, Kristian Rost; Kongstad, J.; Schmidt, I. K.

2012-01-01

of these differences in response in dry versus rewetting conditions can be used to highlight the limitations coherent in different strategies adopted by, for example, evergreen shrubs and grasses. We investigated the leaf-level photosynthetic performance, leaf C, N and d13C along with vegetation cover and biomass...... in the evergreen dwarf shrub Calluna vulgaris and the grass species Deschampsia flexuosa in a temperate heath during seasonal changes in soil moisture. Higher photosynthetic capacity compensated for lower stomatal conductance and sustained higher rates of photosynthesis in the grass compared to the dwarf shrub....... In combination with dieback of aboveground biomass and reduction of stomatal conductance reduction during dry conditions, the grass continued to have high carbon uptake in the remaining leaves. The dwarf shrub endured the dry conditions by preserving shoot biomass and reducing stomatal conductance. Soil...

Steppe bison paleobiology through the scope of stable isotopes and zooarchaeology

Science.gov (United States)

Julien, Marie-Anne; Dorothée, Drucker; Hervé, Bocherens; Ariane, Burke; Marylène, Patou-Mathis; Alexandra, Krotova

2010-05-01

Bison are one of the most abundant and widely distributed species of large mammal during the Late Pleistocene. In the southern steppes of Eastern Europe, steppe bison (Bison priscus) is ubiquitous in zooarchaeological assemblages, particularly during the Upper Palaeolithic when a model of economic "specialization" is proposed. Specialization, in this context, implies the deliberate selection of a preferred species, which becomes the key food resource. The applicability of a specialised hunting model for the Upper Palaeolithic of Europe has recently been challenged, however (Grayson & Delpech 2002). In this research, therefore we re-examine bison acquisition strategies during the Upper Palaeolithic in the Ukrainian steppes in the light of biogeochemical and zooarchaeological data. The acquisition strategies used to procure a prey species are directly related to its social and spatial behaviour. A synthesis of ethological information for contemporary bison (Julien 2009) demonstrates the behavioural diversity of this taxa, linked mainly to local environmental variability, climatic conditions and population density. It is therefore necessary to propose a paleoethological model for the steppe bison before attempting to identify the acquisition strategies used by prehistoric hunters. In this research, we reconstruct the behaviour of the steppe bison using a combination of zooarchaeological tools, stable isotope analysis (intra-tooth isotope variation of carbon, oxygen and strontium ratios) and traditional paleobiological approaches. The advantages of using a combined approach are demonstrated through the examination of a case study: the site of Amvrosievka (Ukraine). Amvrosievka is a complex of Epigravettian sites composed of a camp and kill site, where more than 500 bison are represented (Krotova & Belan 1993). Twenty-five permanent lower teeth (M3) representing twenty-five individual bison were selected from the kill and camp site for isotopic analysis. Intra- and

Methods for measuring arctic and alpine shrub growth

DEFF Research Database (Denmark)

Myers-Smith, Isla; Hallinger, Martin; Blok, Daan

2015-01-01

Shrubs have increased in abundance and dominance in arctic and alpine regions in recent decades. This often dramatic change, likely due to climate warming, has the potential to alter both the structure and function of tundra ecosystems. The analysis of shrub growth is improving our understanding...... of tundra vegetation dynamics and environmental changes. However, dendrochronological methods developed for trees, need to be adapted for the morphology and growth eccentricity of shrubs. Here, we review current and developing methods to measure radial and axial growth, estimate age, and assess growth...... dynamics in relation to environmental variables. Recent advances in sampling methods, analysis and applications have improved our ability to investigate growth and recruitment dynamics of shrubs. However, to extrapolate findings to the biome scale, future dendroecologicalwork will require improved...

Photosynthetic response of Eriophorum vaginatum to in situ shrub shading in tussock tundra of northern Alaska

Science.gov (United States)

Anderson-Smith, A.; Pattison, R.; Sullivan, P.; Welker, J. M.

2009-12-01

Eriophorum vaginatum (Cotton Grass) is an important component of moist acidic tussock tundra, a plant community that appears to be undergoing changes in species composition associated with climate warming. This species is one of the most abundant in the arctic tundra, and provides important forage for caribou in their calving grounds on the Arctic Coastal Plain and along their migratory route through the foothills of Alaska. Recently, remote sensing data, repeat photography and plot-level measurements have indicated that shrub abundance is increasing while Eriophorum abundance is either constant or decreasing. One possible explanation for the reduction of Eriophorum while Betula nana is increasing, is that lower light levels in the taller Betula canopy may be constraining Eriophorum photosynthesis and subsequently reducing plant growth. This study measured the effect of shading on the light response of Eriphorum leaf photosynthesis in four different sites near Toolik Lake Alaska during the summer of 2009. Measurements were taken in: 1) a shrub patch within the drift zone of the ITEX long term snow fence experiment, 2) an LTER shade house (50% shading) built in 1989, 3) water track site 1 and water track site 2 (i.e. control areas with no experimental manipulations) Average photosynthetic rates for Eriophorum at a light level of 800 PAR varied from 3.8 to 10.9 umol m-2 s-1 and were not significantly different in shaded and unshaded areas. This study indicates that shading by shrubs does not appear to be altering the light response of Eriophorum nor does long-term shading by itself eliminate Eriophorum from the community. An alternative explanation for the decline of Eriophorum while Betula increases in abundance under changing climates may be related to plant and soil mineral nutrition, plant water relations or biotic processes involving herbivores.

On the issue of taxonomical status of steppe viper (Vipera renardi in Right-bank Ukraine

Directory of Open Access Journals (Sweden)

A. L. Baybuz

2011-07-01

Full Text Available Data on morphologic variability of the steppe viper in the Kirovograd region (Right-bank Ukraine are given firstly. Tentative estimation of the similaritylevel of the local population and the populations from the Left-bank Ukraine and the Crimea was carried out using methods of the multivariate statistics. Morphological data in line with the results of mitochondrial DNA analysis show that the population in the Kirovograd region belongs to widespread Eurasian species Vipera renardiand morphologically most close to the original populations of the lowland Crimea, Sivash and Forest-Steppe of the Left-bank Ukraine. This could indicate the complicated history of the Right-bank Ukraine colonization by the steppe viper and possible influence of environmental conditions on the vipers’ morphology

Meta-STEPP: subpopulation treatment effect pattern plot for individual patient data meta-analysis.

Science.gov (United States)

Wang, Xin Victoria; Cole, Bernard; Bonetti, Marco; Gelber, Richard D

2016-09-20

We have developed a method, called Meta-STEPP (subpopulation treatment effect pattern plot for meta-analysis), to explore treatment effect heterogeneity across covariate values in the meta-analysis setting for time-to-event data when the covariate of interest is continuous. Meta-STEPP forms overlapping subpopulations from individual patient data containing similar numbers of events with increasing covariate values, estimates subpopulation treatment effects using standard fixed-effects meta-analysis methodology, displays the estimated subpopulation treatment effect as a function of the covariate values, and provides a statistical test to detect possibly complex treatment-covariate interactions. Simulation studies show that this test has adequate type-I error rate recovery as well as power when reasonable window sizes are chosen. When applied to eight breast cancer trials, Meta-STEPP suggests that chemotherapy is less effective for tumors with high estrogen receptor expression compared with those with low expression. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Homeostasis in leaf water potentials on leeward and windward sides of desert shrub crowns: water loss control vs. high hydraulic efficiency.

Science.gov (United States)

Iogna, Patricia A; Bucci, Sandra J; Scholz, Fabián G; Goldstein, Guillermo

2013-11-01

Phenotypic plasticity in morphophysiological leaf traits in response to wind was studied in two dominant shrub species of the Patagonian steppe, used as model systems for understanding effects of high wind speed on leaf water relations and hydraulic properties of small woody plants. Morpho-anatomical traits, hydraulic conductance and conductivity and water relations in leaves of wind-exposed and protected crown sides were examined during the summer with nearly continuous high winds. Although exposed sides of the crowns were subjected to higher wind speeds and air saturation deficits than the protected sides, leaves throughout the crown had similar minimum leaf water potential (ΨL). The two species were able to maintain homeostasis in minimum ΨL using different physiological mechanisms. Berberis microphylla avoided a decrease in the minimum ΨL in the exposed side of the crown by reducing water loss by stomatal control, loss of cell turgor and low epidermal conductance. Colliguaja integerrima increased leaf water transport efficiency to maintain transpiration rates without increasing the driving force for water loss in the wind-exposed crown side. Leaf physiological changes within the crown help to prevent the decrease of minimum ΨL and thus contribute to the maintenance of homeostasis, assuring the hydraulic integrity of the plant under unfavorable conditions. The responses of leaf traits that contribute to mechanical resistance (leaf mass per area and thickness) differed from those of large physiological traits by exhibiting low phenotypic plasticity. The results of this study help us to understand the unique properties of shrubs which have different hydraulic architecture compared to trees.

Does browsing reduce shrub survival and vigor following summer fires?

Science.gov (United States)

Fulbright, Timothy E.; Dacy, Emily C.; Drawe, D. Lynn

2011-01-01

Periodic fire is widely hypothesized to limit woody plant encroachment in semiarid grasslands. In southern Texas, however, most of the woody plants that have invaded grasslands during the past two centuries are resistant to fire. We hypothesized that browsing by Odocoileus virginianus increases mortality of palatable shrubs and reduces vigor of shrubs following fire. We randomly selected ten pairs of each of three shrub species -Condalia hookeri, Acacia farnesiana, and Celtis ehrenbergiana - in each of three locations before prescribed burns during summer 2001. Following burns, we used a wire fence to protect one shrub of each pair from browsing. We estimated intensity of O. virginianus browsing and number and height of sprouts 4, 12, 20, 30, 38, and 47 weeks post-fire. We determined shrub height, survival, and biomass one year post-fire. Averaged across species, browsing intensity on unfenced shrubs was greater (LS Means, P 0.05) one year post-burn. Browsing by O. virginianus at the intensity in our study does not increase mortality or reduce vigor of C. hookeri, A. farnesiana, and Condalia ehrenbergiana producing new growth following destruction of aboveground tissues by a single fire compared to shrubs that are not browsed following fire.

Magnetic Soils Profiles in the Volga-Kama Forest-Steppe Region

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L.A. Fattakhova

2016-09-01

Full Text Available The magnetic properties of virgin forest-steppe soils developed on the originally vertically uniform unconsolidated parent material have been investigated. The profile samples of virgin dark-grey forest light-clayey soil derived from a siltstone of the Kazan layer of the Upper Permian and virgin leached medium-thick fertile light-clayey chernozem derived from a Quaternary heavy deluvial loam have been considered. Both soils are characterized by the accumulative type of magnetic susceptibility and F-factor values distribution patterns with depth. In the humus part of the soil profile, magnetics are present pre-dominantly in the < 2.5 µm fraction. The coercivity spectra allowed to determine the contribution of dia-/paramagnetic and ferromagnetic components to magnetic susceptibility. It has been found that magnetic susceptibility enhancement in the organogenic horizons of virgin forest-steppe soils occurs due to the contribution of ferromagnetic components. The results indicate a strong positive linear correlation between the magnetic susceptibility and oxalate-extractable Fe, as well as between the magnetic susceptibility and Schwertmann’s criterion values. Using the method of thermomagnetic analysis of the < 2.5 µm fraction, it has been found that the magnetic susceptibility enhancement in the profiles of forest-steppe soils took place due to the formation of maghemite-magnetite associations. The predominantly ferromagnetic fraction consists of small single-domain grains.

Assessment and prediction of the invasiveness of some alien plants in conditions of climate change in the steppe Dnieper region

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Y. V. Lykholat

2017-02-01

Full Text Available The flora of the steppe Dnieper region is characterized by an abundance of naturalized alien species, some of which colonised over the last decade. Climate change, associated primarily with increasing temperature, became clearly manifested in this period. We tested the hypothesis that there is an association between climate change and the initiation of invasiveness of some alien plant species in the steppe Dnieper region. For this purpose, comparative studies of the distribution boundaries of naturalized alien trees, shrubs and herbaceous plants were conducted. Along the research route numerous 5–10-year-old broadleaf linden trees (Tilia platyphyllos Scop. were found in the man-made plantation communities of Dnipro city in areas with moist soil; seeded undergrowth was located at a significant distance from the adult linden plants. Numerous groups of young 7–10-year-old plants of the smoke trees (Cotinus coggygria Scop., which had a seed origin, were found in the shelterbelt and urban recreational plantations. Young 10–12-year-old virginal and generative plants of the black cherry (Padus serotina Ehrh. were found in large numbers in both the semi-natural and artificial plant communities at great distances from the adult trees. The alien plant species common hackberry (Celtis occidentalis L. showed the ability to form fairly sparse seminal seedlings, which was presented by the plants at the age of 4–7 years in both the natural and urban plant communities. The perennial herbaceous plant common milkweed (Asclepias syriaca L. was found in the course of the research in ruderal habitats, urban plant communities, and also in the agrocoenoses. The common milkweed reached its greatest abundance in fields of winter crops, where the spread of this species was accompanied by a sharp decrease in the number of other species of segetal plants. Our study results confirm that the extension of the distribution boundaries of alien species over the last

Dating simple flakes: Early Bronze Age flake production technology on the Middle Euphrates Steppe, Syria

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Yoshihiro Nishiaki

2014-03-01

Full Text Available Aceramic flint scatters, comprising very crude cores or flakes and no formalised tools, are frequently found on the Middle Euphrates steppe of northern Syria. Previous studies suggest that many of them are residues of short-term activities by the nomads or shepherds of the Early Bronze Age. In order to verify this interpretation, a more precise chronological framework needs to be established for the Early Bronze Age lithic industry. This paper analyses stratified flake assemblages of the Early Bronze Age at Tell Ghanem al-Ali, a securely radiocarbon-dated settlement on the Middle Euphrates, and examines which occupation level yields assemblages most similar to those of the steppe. Results demonstrate that the lithic industry of this period underwent significant diachronic changes in terms of core reduction technology. Based on the chronological framework developed at Tell Ghanem al-Ali, the steppe assemblages in question can be assigned to different phases of the Early Bronze Age. This finding will help identify processes at the beginning of the extensive exploitation of the steppe, which is regarded as one of the most important socioeconomic changes that occurred among Early Bronze Age communities of the Middle Euphrates.

Polen y vegetación en la Patagonia extraandina argentina a 45º S

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Burry, Lidia S.

2005-12-01

Full Text Available Modern pollen dispersal and deposition in relation to vegetation and environmental variables at 45° S was studied in Argentinian Patagonia east of the Andes to build a modern pollen model. This model will serve to identify modern pollen assemblages that are analog of past pollen assemblages. A west-to-east gradient of decreasing precipitation and increasing temperature determines four vegetation units: (1 grass steppe, (2 grass-bush steppe, (3 bush steppe and (4 bush-brush steppe. Pollen samples were analyzed by classification and ordination methods, and correlated to environmental variables. The steppes (a dominated by the functional type grass, (1 grass steppe, and (2 grass-bush steppe located in the more humid and cooler west end of the region were separated from the (b bush-dominated steppes (3 bush steppe and (4 bush-brush steppe occurring in the central and eastern parts of the region, where conditions are drier and warmer. Azonal communities were identified as halophytic bush steppes within different vegetation units along the west-east gradient. Environmental variables related to vegetation distribution are temperature and interannual precipitation variability associated with the precipitation gradient from the cordillera to the coast, and soil salinity in the case of azonal communities.Se investigó la relación de la dispersión-deposición del polen actual con la vegetación y con variables ambientales en la Patagonia extraandina argentina a 45° S con el fin de construir un modelo polínico actual. Este modelo servirá para identificar los conjuntos polínicos actuales que sean análogos de conjuntos polínicos fósiles. En la región hay un gradiente decreciente de precipitación y creciente de temperatura de oeste a este, que determina la existencia de diferentes unidades de vegetación: (1 estepa graminosa; (2 estepa graminosa-arbustiva; (3 estepa arbustiva y (4 estepa arbustiva-matorral. Los datos de polen de muestras de suelo

tree and shrub species integration in the crop-livestock farming ...

African Journals Online (AJOL)

Prof. Adipala Ekwamu

cash for investment in the required activities, easy land certification and market opportunity for tree and shrub products. The tree and shrub .... for its consistency, logical flow, coding and length were amended. .... TABLE 2. List of shrub species identified in the watershed of highlands of central Ethiopia. Scientific name.

[Team Care for Patient Safety, TeamSTEPPS to Improve Nontechnical Skills and Teamwork--Actions to Become an HRO].

Science.gov (United States)

Kaito, Ken

2015-07-01

It is important to develop safer medical systems and follow manuals of medical procedures for patient safety. However, these approaches do not always result in satisfactory results because of many human factors. It is known that defects of nontechnical skills are more important than those of technical skills regarding medical accidents and incidents. So, it is necessary to improve personal nontechnical skills and compensate for each other's defects based on a team approach. For such purposes, we have implemented TeamSTEPPS to enhance performance and patient safety in our hospital. TeamSTEPPS (team strategies and tools to enhance performance and patient safety) is a useful method to improve the nontechnical skills of each member and the team. In TeamSTEPPS, leadership to share mental models among the team, continuous monitoring and awareness for team activities, mutual support for workload and knowledge, and approaches to complete communication are summarized to enhance teamwork and patient safety. Other than improving nontechnical skills and teamwork, TeamSTEPPS is also very important as a High Reliability Organization (HRO). TeamSTEPPS is worth implementing in every hospital to decrease medical errors and improve patient outcomes and satisfaction.

NPP Grassland: Pampa De Leman, Argentina, 1980-1982, R1

Data.gov (United States)

National Aeronautics and Space Administration — This data set contains two ASCII files (.txt format). One file contains monthly productivity data measured on an arid dwarf-shrub steppe in northern Patagonia,...

New insights into the paleoenvironment of northern Israel during the Last Glacial

Science.gov (United States)

Miebach, Andrea; Chen, Chunzhu; Schwab, Markus J.; Lev, Lilach; Stein, Mordechai; Litt, Thomas

2016-04-01

Archaeological findings in the vicinity of the Dead Sea rift display the outstanding role of the region for reconstructing human history. The environmental settings of the historical developments are obtained from the sedimentary sections that were accumulated in the lakes occupying the tectonic depressions along the rift. Here, we focus on the vegetation history in the vicinity of the Sea of Galilee (Lake Kinneret), northern Israel, during MIS2 when the lake reached its high stands and even merged with the southern Lake Lisan at an elevation of ~ 170 m below sea level (cf. Hazan et al., 2005). A continuous vegetation and climate record could provide valuable insights into the environmental context of human developments. We analyzed pollen from sediment cores that were drilled at the Ohalo II archaeological site at the southwestern shore of the Sea of Galilee. New radiocarbon dates refined the age-depth model. Most of the cores comprise laminated authigenic calcites and detritus material that was deposited between ~27,000 to 22,000 years before present. The Sea of Galilee is currently the lowest freshwater lake on the Earth (209 m below mean sea level). It is situated in the Mediterranean climate and vegetation zone of northern Israel. Further to the south and east, the Mediterranean biome is displaced by steppe and desert due to considerably lower precipitations. Our results suggest that a steppe with dwarf shrubs, herbs, and grasses predominated in northern Israel during the Last Glacial. In contrast to the Holocene, there was no vegetation belt of the Mediterranean biome in the vicinity of the Sea of Galilee. Deciduous oaks were the dominant trees, although they only occurred in limited amounts. Trees and shrubs were almost absent during most arid periods. While the pollen data may indicate semiarid conditions (less precipitation) in the vicinity of the Sea of Galilee, the high lake levels and deposition of authigenic calcite require enhanced freshwater input to

Independent Effects of Invasive Shrubs and Deer Herbivory on Plant Community Dynamics

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Jeffrey S. Ward

2016-12-01

Full Text Available Both invasive species and deer herbivory are recognized as locally important drivers of plant community dynamics. However, few studies have examined whether their effects are synergistic, additive, or antagonistic. At three study areas in southern New England, we examined the interaction of white-tailed deer (Odocoileus virginianus Zimmermann herbivory and three levels of invasive shrub control over seven growing seasons on the dynamics of nine herbaceous and shrub guilds. Although evidence of synergistic interactions was minimal, the separate effects of invasive shrub control and deer herbivory on plant community composition and dynamics were profound. Plant communities remained relatively unchanged where invasive shrubs were not treated, regardless if deer herbivory was excluded or not. With increasing intensity of invasive shrub control, native shrubs and forbs became more dominant where deer herbivory was excluded, and native graminoids became progressively more dominant where deer herbivory remained severe. While deer exclusion and intensive invasive shrub control increased native shrubs and forbs, it also increased invasive vines. Restoring native plant communities in areas with both established invasive shrub thickets and severe deer browsing will require an integrated management plan to eliminate recalcitrant invasive shrubs, reduce deer browsing intensity, and quickly treat other opportunistic invasive species.

The role of symbiotic nitrogen fixation in nitrogen availability, competition and plant invasion into the sagebrush steppe

Science.gov (United States)

Erin M. Goergen

2009-01-01

In the semi-arid sagebrush steppe of the Northeastern Sierra Nevada, resources are both spatially and temporally variable, arguably making resource availability a primary factor determining invasion success. N fixing plant species, primarily native legumes, are often relatively abundant in sagebrush steppe and can contribute to ecosystem nitrogen budgets. ...

Dynamic contents of energy and organic nutrient in steppe growths of the Mohelenská Serpentine Steppe National Nature Reserve

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Pavel Veselý

2006-01-01

Full Text Available The aim of the study was to determine the dynamics in the content of organic nutrients, ash and energy in dry matter of growths within the Mohelenská Serpentine Steppe National Nature Reserve (NPR, and to document their initial nutritive value before the intended grazing. Plant samples in 1995 and 1996 during the growing season in 14-days intervals from the area of 3 × 1 m2. Amounts of dry matter, fibre, nitrogen substances, fat and ashes were determined in growths according to the ANONYM (2001. Nitrogen-free extract substances (BNLV were determined by final calculating; BE, ME, NEL, NEV, PDIN and PDIE were calculated using the regression equations (VESELÝ and ZEMAN, 1995, 1997. Combining ratio (SP was calculated according to the relation: SP = PDIN (g/NEL (MJ. The dynamics of the contents of dry matter, organic nutrients, ashes and energy were assessed in the growth during the vegetation period and the dynamics was compared with standardized requirements of sheep (no pregnant ewe. Regression and correlation relations for nutrition value of the growths during vegetation period were calculated by use of mathematical-statistical analysis. Only statistically significantly (P<0.05 different parameters form the zero are presented in the paper. The content of dry matter in the growths culminated in summer months (places D8, E13, B17 and it was accompanied by depression in autumn months. After the highest content of crude protein, PDIN and PDIE recorded in spring months summer depression (August followed, this depression was partly balanced by autumn growth of vegetation. The content of ash in steppe growths increased during evaluated period. Similar tendency was registered for fat. Also the contents of fibre and BNLV linearly increased. The contents of nitrogen nutrients and energy corresponded with standardized requirements for sheep during whole vegetation period. Conversely the content of fibre highly exceeded the requirement except in spring

Gene Expression Profiling of Grass Carp (Ctenopharyngodon idellus and Crisp Grass Carp

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Ermeng Yu

2014-01-01

Full Text Available Grass carp (Ctenopharyngodon idellus is one of the most important freshwater fish that is native to China, and crisp grass carp is a kind of high value-added fishes which have higher muscle firmness. To investigate biological functions and possible signal transduction pathways that address muscle firmness increase of crisp grass carp, microarray analysis of 14,900 transcripts was performed. Compared with grass carp, 127 genes were upregulated and 114 genes were downregulated in crisp grass carp. Gene ontology (GO analysis revealed 30 GOs of differentially expressed genes in crisp grass carp. And strong correlation with muscle firmness increase of crisp grass carp was found for these genes from differentiation of muscle fibers and deposition of ECM, and also glycolysis/gluconeogenesis pathway and calcium metabolism may contribute to muscle firmness increase. In addition, a number of genes with unknown functions may be related to muscle firmness, and these genes are still further explored. Overall, these results had been demonstrated to play important roles in clarifying the molecular mechanism of muscle firmness increase in crisp grass carp.

Trace metals bioaccumulation potentials of three indigenous grasses grown on polluted soils collected around mining areas in Pretoria, South Africa

International Nuclear Information System (INIS)

Lion, G. N.; Olowoyo, J. O.; Modise, T. A.

2016-01-01

The rapid increase in the number of industries may have increased the levels of trace metals in the soil. Phyto remediation of these polluted soils using indigenous grasses is now considered an alternative method in re mediating these polluted soils. The present study investigated and compared the ability of three indigenous grasses as bioaccumulators of trace metals from polluted soils. Seeds of these grasses were introduced into pots containing polluted soil samples after the addition of organic manure. The seeds of the grasses were allowed to germinate and grow to maturity before harvesting. The harvested grasses were later separated into shoots and roots and the trace metal contents were determined using ICP –MS. From all the grasses, the concentrations of trace metals in the roots were more than those recorded in the shoot with a significant difference (P Themeda trianda > Cynodon dactylon. The study concluded that the three grasses used were all able to bioaccumulate trace metals in a similar proportion from the polluted soils. However, since livestock feed on these grasses, they should not be allowed to feed on the grasses used in this study especially when harvested from a polluted soil due to their bioaccumulative potentials. (au)

Rhizosphere bacterial communities of dominant steppe plants shift in response to a gradient of simulated nitrogen deposition

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An eYang

2015-08-01

Full Text Available We evaluated effects of 9-year simulation of simulated nitrogen (N deposition on microbial composition and diversity in the rhizosphere of two dominant temperate grassland species: grass Stipa krylovii and forb Artemisia frigida. Microbiomes in S. krylovii and A.frigida rhizosphere differed, but changed consistently along the N gradient. These changes were correlated to N-induced shifts to plant community. Hence, as plant biomass changed, so did bacterial rhizosphere communities, a result consistent with the role that N fertilizer has been shown to play in altering plant-microbial mutualisms. A total of 23 bacterial phyla were detected in the two rhizospheric soils by pyrosequencing, with Proteobacteria, Acidobacteria and Bacteroidetes dominating the sequences of all samples. Bacterioidetes and Proteobacteria tended to increase, while Acidobacteria declined with increase in N addition rates. TM7 increased >5-fold in the high N addition rates, especially in S. krylovii rhizosphere. Nitrogen addition also decreased diversity of OTUs (operational taxonomic units, Shannon and Chao1 indices of rhizospheric microbes regardless of plant species. These results suggest that there were both similar but also specific changes in microbial communities of temperate steppes due to N deposition.

The Influence of an Invasive Shrub, Buddleja Davidii on a Native Shrub, Griselinia Littoralis Transplanted into a New Zealand Floodplain Chronosequence

Science.gov (United States)

Griselinia littoralis, a native New Zealand shrub, was planted into a chronosequence (0 to 8 yrs since flooding) dominated by the non-indigenous shrub, Buddleja davidii in three New Zealand floodplains to determine to what extent facilitation and competitive inhibition may influe...

Vegetation Responses to Prescribed Burning of Grazed Shortgrass Steppe

Science.gov (United States)

Over the past century, fire has been widely suppressed in the western Great Plains, in part due to potential negative effects on forage production for livestock. More recently, interest in the use of prescribed fire in shortgrass steppe has increased due to potential applications for wildlife manage...

Aggregate-associated carbon and nitrogen in reclaimed sandy loam soils

Energy Technology Data Exchange (ETDEWEB)

Wick, A.F.; Stahl, P.D.; Ingram, L.J. [Virginia Polytechnic Institute & State University, Blacksburg, VA (United States)

2009-11-15

Minimal research has been conducted on aggregate, C, and N in coarse-textured soils used to reclaim surface coal mine lands. Furthermore, little is known about the contribution different plant communities make to the recovery of aggregation in these soils. Two chronosequences of semiarid reclaimed sites with sandy loam soils were sampled under shrub- and grass-dominated communities. Aggregation, aggregate fractions, and associated C and N were measured. No definitive trends of increasing macroaggregates between sites were observed undershrubs; however, macro- and microaggregation was greater in the 16-yr-old (0.20 and 0.23 kg aggregate kg{sup -1} soil, respectively) than in the 5-yr-old soils (0.02 and 0.08 kg aggregate kg{sup -1} soil, respectively) under grasses. Although C and N concentrations were drastically reduced (50-75%) with mining activity between the <1-yr-old and native soils, aggregate C and N concentrations tinder shrubs and grasses were similar to each other and to the native soils in the 5-yr-old site. Sods under grass in the 16-yr-old site had lower available and aggregate-occluded C and N concentrations than the 5-yr-old site, while C and N concentrations did not change between 5- and 16-yr-old soils under shrubs. Conversely, aggregate C and N pool sizes under shrubs and grasses both increased with site age to conditions similar to those observed in the native soil. Reclaimed shrub site soils had consistently higher C concentrations in the older reclaimed sites (10 and 16 yr old) than the soils under grasses, indicating greater accumulation and retention of C and N in organic material under shrub than grass communities in semiarid reclaimed sites.

Tundra shrub effects on growing season energy and carbon dioxide exchange

Science.gov (United States)

Lafleur, Peter M.; Humphreys, Elyn R.

2018-05-01

Increased shrub cover on the Arctic tundra is expected to impact ecosystem-atmosphere exchanges of carbon and energy resulting in feedbacks to the climate system, yet few direct measurements of shrub tundra-atmosphere exchanges are available to corroborate expectations. Here we present energy and carbon dioxide (CO2) fluxes measured using the eddy covariance technique over six growing seasons at three closely located tundra sites in Canada’s Low Arctic. The sites are dominated by the tundra shrub Betula glandulosa, but percent cover varies from 17%–60% and average shrub height ranges from 18–59 cm among sites. The site with greatest percent cover and height had greater snow accumulation, but contrary to some expectations, it had similar late-winter albedo and snow melt dates compared to the other two sites. Immediately after snowmelt latent heat fluxes increased more slowly at this site compared to the others. Yet by the end of the growing season there was little difference in cumulative latent heat flux among the sites, suggesting evapotranspiration was not increased with greater shrub cover. In contrast, lower albedo and less soil thaw contributed to greater summer sensible heat flux at the site with greatest shrub cover, resulting in greater total atmospheric heating. Net ecosystem exchange of CO2 revealed the potential for enhanced carbon cycling rates under greater shrub cover. Spring CO2 emissions were greatest at the site with greatest percent cover of shrubs, as was summer net uptake of CO2. The seasonal net sink for CO2 was ~2 times larger at the site with the greatest shrub cover compared to the site with the least shrub cover. These results largely agree with expectations that the growing season feedback to the atmosphere arising from shrub expansion in the Arctic has the potential to be negative for CO2 fluxes but positive for turbulent energy fluxes.

Mean species cover: a harmonized indicator of shrub cover for forest inventories

Science.gov (United States)

Iciar Alberdi; Sonia Condés; Ronald E. Mcroberts; Susanne Winter

2018-01-01

Because shrub cover is related to many forest ecosystem functions, it is one of the most relevant variables for describing these communities. Nevertheless, a harmonized indicator of shrub cover for large-scale reporting is lacking. The aims of the study were threefold: to define a shrub indicator that can be used by European countries for harmonized shrub cover...

Effects of conventional and grass-feeding systems on the nutrient composition of beef.

Science.gov (United States)

Leheska, J M; Thompson, L D; Howe, J C; Hentges, E; Boyce, J; Brooks, J C; Shriver, B; Hoover, L; Miller, M F

2008-12-01

The objectives of this study were to determine the nutrient composition of grass-fed beef in the United States for inclusion in the USDA National Nutrient Database for Standard Reference, and to compare the fatty acid composition of grass-fed and conventionally fed (control) beef. Ground beef (GB) and strip steaks (SS) were collected on 3 separate occasions from 15 grass-fed beef producers that represented 13 different states, whereas control beef samples were collected from 3 regions (Ohio, South Dakota, and Texas) of the United States on 3 separate occasions. Concentrations of minerals, choline, vitamin B(12), and thiamine were determined for grass-fed beef samples. Grass-fed GB samples had less Mg, P, and K (P < 0.05), and more Na, Zn, and vitamin B(12) (P < 0.05) than SS samples. Fat color, marbling, and pH were assessed for grass-fed and control SS. Subjective evaluation of the SS indicated that grass-fed beef had fat that was more yellow in color than control beef. Percentages of total fat, total cholesterol, and fatty acids along with trans fatty acids and CLA were determined for grass-fed and control SS and GB. Grass-fed SS had less total fat than control SS (P = 0.001), but both grass-fed and control SS were considered lean, because their total fat content was 4.3% or less. For both GB and SS, grass-fed beef had significantly less (P = 0.001 and P = 0.023, respectively) content of MUFA and a greater content of SFA, n-3 fatty acids, CLA, and trans-vaccenic acid than did the control samples. Concentrations of PUFA, trans fatty acids, n-6 fatty acids, and cholesterol did not differ between grass-fed and control ground beef. Trans-vaccenic acid (trans-11 18:1) made up the greatest concentration of the total trans fats in grass-fed beef, whereas CLA accounted for approximately 15% of the total trans fats. Although the fatty acid composition of grass-fed and conventionally fed beef was different, conclusions on the possible effects of these differences on human

Treatment with grass allergen peptides improves symptoms of grass pollen-induced allergic rhinoconjunctivitis.

Science.gov (United States)

Ellis, Anne K; Frankish, Charles W; O'Hehir, Robyn E; Armstrong, Kristen; Steacy, Lisa; Larché, Mark; Hafner, Roderick P

2017-08-01

Synthetic peptide immunoregulatory epitopes are a new class of immunotherapy to treat allergic rhinoconjunctivitis (ARC). Grass allergen peptides, comprising 7 synthetic T-cell epitopes derived from Cyn d 1, Lol p 5, Dac g 5, Hol l 5, and Phl p 5, is investigated for treatment of grass pollen-induced ARC. We sought to evaluate the efficacy, safety, and tolerability of intradermally administered grass allergen peptides. A multicenter, randomized, double-blind, placebo-controlled study evaluated 3 regimens of grass allergen peptides versus placebo in patients with grass pollen-induced allergy (18-65 years). After a 4-day baseline challenge to rye grass in the environmental exposure unit (EEU), subjects were randomized to receive grass allergen peptides at 6 nmol at 2-week intervals for a total of 8 doses (8x6Q2W), grass allergen peptides at 12 nmol at 4-week intervals for a total of 4 doses (4x12Q4W), or grass allergen peptides at 12 nmol at 2-week intervals for a total of 8 doses (8x12Q2W) or placebo and treated before the grass pollen season. The primary efficacy end point was change from baseline in total rhinoconjunctivitis symptom score across days 2 to 4 of a 4-day posttreatment challenge (PTC) in the EEU after the grass pollen season. Secondary efficacy end points and safety were also assessed. Two hundred eighty-two subjects were randomized. Significantly greater improvement (reduction of total rhinoconjunctivitis symptom score from baseline to PTC) occurred across days 2 to 4 with grass allergen peptide 8x6Q2W versus placebo (-5.4 vs -3.8, respectively; P = .0346). Greater improvement at PTC also occurred for grass allergen peptide 8x6Q2W versus placebo (P = .0403) in patients with more symptomatic ARC. No safety signals were detected. Grass allergen peptide 8x6Q2W significantly improved ARC symptoms after rye grass allergen challenge in an EEU with an acceptable safety profile. Copyright © 2017 American Academy of Allergy, Asthma & Immunology

Shrubs of the Field Irradiator - Gamma area in eastern Manitoba

International Nuclear Information System (INIS)

Dugle, J.R.; Mayoh, K.R.; Barclay, P.J.

1979-11-01

Detailed descriptions and line drawings are given of over 100 shrub taxa (including semi-woody shrubs and vines) which are common in Manitoba; most of them are found within the Field Irradiator - Gamma (FIG) area or its immediate surroundings. Ecological and morphological notes are included along with a few general remarks on the effects of exposure to long-term gamma radiation. Keys are given for certain genera, small family groups or other critical species groups. This document is intended to facilitate identification of shrubs for experimental purposes in the FIG projects, and it should also be useful to those who are generally interested in the shrubs of Manitoba. (auth)

HYGROTOPE AND TROPHOTOPE OF THE STEPPE PRIDNIPROVIE BIOGEOCEONOSIS AS DETERMINANTS OF THE EARTHWORMS (LUMBRICIDAE COMMUNITIES β-DIVERSITY

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A. V. Zhukov

2016-08-01

Full Text Available The role of the hygrotope and trophotope of the steppe Pridniprovie biogeoceonosis has been discussed in present article as being determinants of the β-diversity of earthworms (Lumbricidae communities. Material has been colected to the period 1997-2015. 180 sample polygons have been studied which located in various types of biogeoceonosis. Biogeoceonotic characteristic of the sample polygons have been made on the basis of professor A.L. Belgard forest typology of a steppe zone of Ukraine. Earthworm communities of the steppe Pridniprovie have been established to be presented by 16 species. Hygrotopes, trophotopes and bitope ceonosis features have been shown to be able to explain 72.4 % of a communities’ abundance variation and 73.7 of their % α-diversity by means of second order model. Earthworm communities’ abundance reache their maximum values at a combination of conditions of humidity from hygromesophilous to hygrophilous and conditions of edaphotope trophicity from Dc (linden oakwood to Dn (elm-ashen oakwood and alder forests. The maximum diversity of earthworm communities has been stated to be characteristic for a combination of mesohygrophilous conditions and a trophicity mode Dc, that there corresponds to forest type a linden oakwood with aegopodium. The coenomorphic structure of the biogeocoenosis is statistically significant predictors of both abundance and α-diversity of earthworm communities. Earthworm communities of marsh monocoenosis, meadow-steppe amphicoenosis and steppe monocoenosis have been found as being characterised by minimum abundance and diversity. Moderate level abundance and diversity are characteristic for meadow-forest amphicoenosis, forest pseudomonocoenosis with elements of transformation to steppe and forest-steppe amphicoenosis. High levels of these indexes are typical for forest monocoenosis. Given other conditions of humidity and edaphotope trophicity being equal in forest monocoenosis abundance and

A leadership challenge: staff nurse perceptions after an organizational TeamSTEPPS initiative.

Science.gov (United States)

Castner, Jessica; Foltz-Ramos, Kelly; Schwartz, Diane G; Ceravolo, Diane J

2012-10-01

The purpose of this study was to measure RNs' perceptions of teamwork skills and behaviors in their work environment during a multiphase multisite nursing organizational teamwork development initiative. Teamwork is essential for patient safety in healthcare organizations and nursing teams. Organizational development supporting effective teamwork should include a just culture, engaged leadership, and teamwork training. A cross-sectional survey study of bedside RNs was conducted in one 5-hospital healthcare system after a TeamSTEPPS teamwork training initiative. TeamSTEPPS teamwork training related to improved RN perceptions of leadership. Initiatives to align the perspectives and teamwork efforts of leaders and bedside nurses are indicated and should involve charge nurses in the design.

KIRGHIZ STEPPE IN THE TRAVEL NOTES AND ESSAYS OF M. M. PRISHVIN: IMAGOLOGY AND POETICS

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Elena A. Khudenko

2017-06-01

Full Text Available The article investigates the cross-cutting images and themes related to topography of the Kirghiz steppe (now North-Eastern Kazakhstan in the works of M. M. Prishvin. Three early Prishvin’s texts — a Siberian diary “A Journey from Pavlodar to Karkaralinsk”, essays “Adam and Eve” and “A Black Arab” became an empirical base for it. The marginality of Prishvin’s texts in which the itinerant writer crosses the border between Europe and Asia as well as the border of consciousness, dwelling simultaneously in the space of its own and in the others’ space, permitted to reconstruct the landscape consciousness of the Kirghiz and Russian emigrees. The methodological feature of the study of these works along with the study of the poetics of the steppe images, the Kazakh, local legends and nomadic subjects, was a description of their imagological component induced by socio-historical, political and ethnic processes of the early twentieth century, the writer talks about in his books. So, the overall strategy of the narrative, moving from a documentary and essay principle to the poetic saturation by images is formed in his diaries. The essay “Adam and Eve” considers the issue of Russian immigrants, demonstrates the incompatibility between sedentary and nomadic life as two types of national behavior. A twofold image of the steppe — a foodless and saline steppe, and a rich and populated one — sets the parameters of social behavior of the rich and the poor in his essay “A Black Arab”. Basing on its materials the distinctive marks of the steppe as the Paradise are explored. Thus, the Asiatic world is seen by Prishvin through the principle of the landscape consciousness, which allowed reconstructing the features of the national image on the whole.

Patterned-ground facilitates shrub expansion in Low Arctic tundra

International Nuclear Information System (INIS)

Frost, Gerald V; Epstein, Howard E; Walker, Donald A; Matyshak, Georgiy; Ermokhina, Ksenia

2013-01-01

Recent expansion of tall shrubs in Low Arctic tundra is widely seen as a response to climate warming, but shrubification is not occurring as a simple function of regional climate trends. We show that establishment of tall alder (Alnus) is strongly facilitated by small, widely distributed cryogenic disturbances associated with patterned-ground landscapes. We identified expanding and newly established shrub stands at two northwest Siberian sites and observed that virtually all new shrubs occurred on bare microsites (‘circles’) that were disturbed by frost-heave. Frost-heave associated with circles is a widespread, annual phenomenon that maintains mosaics of mineral seedbeds with warm soils and few competitors that are immediately available to shrubs during favorable climatic periods. Circle facilitation of alder recruitment also plausibly explains the development of shrublands in which alders are regularly spaced. We conclude that alder abundance and extent have increased rapidly in the northwest Siberian Low Arctic since at least the mid-20th century, despite a lack of summer warming in recent decades. Our results are consistent with findings in the North American Arctic which emphasize that the responsiveness of Low Arctic landscapes to climate change is largely determined by the frequency and extent of disturbance processes that create mineral-rich seedbeds favorable for tall shrub recruitment. Northwest Siberia has high potential for continued expansion of tall shrubs and concomitant changes to ecosystem function, due to the widespread distribution of patterned-ground landscapes. (letter)

Changes in epiphyte communities as the shrub, Acer circinatum, develops and ages

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Ruchty, A.M.; Rosso, A.L.

2001-01-01

The Pacific Northwest tall shrub Acer circinatum (vine maple) can host diverse and abundant epiphyte communities. A chronosequence approach revealed that these communities gradually shift in composition as the shrub progresses through its life cycle. Different epiphytic life forms occupy different spatial and temporal niches on shrub stems. These life forms generally shift upwards along the shrub stem as the stem ages and develops, in accordance with the similar gradient hypothesis. We postulate the following sequence of events. An initial wave of colonization occurs as new substrate is laid down. Over time, superior competitors gradually engulf and overgrow competitively inferior primary colonizers. Concurrently, shrub stem microclimate changes as shrub stems grow, age, and layer, causing the processes of competition and colonization to shift in favor of different epiphytic life forms during different life stages of the shrub stem. We define four separate shrub stem life stages: life classes 1a??4 describe, respectively, young upright a??whipsa??; vigorous, upright, mature stems; declining stems beginning to bend towards the forest floor; and horizontal, decadent stems. As space on the shrub stem is filled through growth and colonization, interspecific competition intensifies. Successful competitors persist and spread, while poor competitors are increasingly restricted to the stem tips, where interspecific competition is less intense. In these forests, Usnea, green-algal foliose lichens, and moss tufts excel as the primary colonizers and become common on the outer portions of shrub stems over time, as long as the overstory is not too dense. Moss mats are also good primary colonizers, but excel as secondary colonizers, often coming to dominate decadent shrub stems. Although all life forms can be primary colonizers, the remaining forms (cyanolichens, liverworts, and Antitrichia curtipendula) are effective secondary colonizers. Liverworts are also effective

Shrub water use dynamics in arctic Alaska

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Clark, J.; Young-Robertson, J. M.; Tape, K. D.

2016-12-01

In the Arctic tundra, hydrologic processes influence the majority of ecosystem processes, from soil thermal dynamics to energy balance and trace gas exchange to vegetation community distributions. The tundra biome is experiencing a broad spectrum of ecosystem changes spurred by 20th century warming, including deciduous shrub expansion. Deciduous woody vegetation typically has high water use rates compared to evergreen and herbaceous species, and is projected to have a greater impact on energy balance than altered albedo from changes in snowpack. However, the impact of greater shrub cover on water balance has been overlooked. Shrubs have the potential to significantly dry the soil, accessing stored soil moisture in the organic layers, while increasing atmospheric moisture. The goal of this study is to quantify the water use dynamics (sap flux and stem water content) of three common arctic shrub species (Salix alexensis, S. pulchra, Betula nana) over two growing seasons. Stem water content was measured through a novel application of time domain reflectometry (TDR). Maximum sap flow rates varied by species: S. alexensis-600g/hr, S. pulchra-60g/hr, and B. nana-40g/hr. We found daily sap flow rates are highly correlated with atmospheric moisture demand (VPD) and not limited by soil moisture or antecedent precipitation. Stem water content varied between 20% and 60%, was correlated with soil moisture, and showed weak diurnal variation. This is one of the first studies to provide a detailed look at arctic tundra shrub water balance and explore the environmental controls on water flux. Planned future work will expand on these results for estimates of evapotranspiration over larger landscape areas.

75 FR 66779 - Ruby Lake National Wildlife Refuge, Elko and White Pine Counties, NV; Comprehensive Conservation...

Science.gov (United States)

2010-10-29

... emanating from the base of the Ruby Mountains provide life-sustaining water to the 39,926-acre refuge. The marsh is surrounded by 22,926 acres of meadows, grasslands, alkali playa, and shrub-steppe uplands...

General Design Memorandum Appendix D, Environmental Documents. Pascagoula Harbor Channel Improvement, Pascagoula, Mississippi

Science.gov (United States)

1992-02-01

herbaceous uplands ( Cogon grass ), and 29 acres of tidal marsh. The entire area includes about 183 acres. 3. Alternative 3 is similar to Alternative 2...acres of tidal wetlands outside of the old Tenneco dike 61 acres of scrub/shrub uplands 21 acres of herbaceous uplands ( Cogon grass ) While wetlands...shrub wetlands exist within the old levees at the Tenneco site. Wetland grasses include such species as threesquare (Sciryus spp.), black needlerush

Spatial analysis of root hemiparasitic shrubs and their hosts

DEFF Research Database (Denmark)

Dueholm, Bjørn; Bruce, David; Weinstein, Philip

2017-01-01

to as spatial signatures of the root hemiparasites. In order to search for such spatial signatures, we investigated a population of a predominant Acacia species in Australia co-occurring with established root hemiparasitic shrubs, using intensity estimates of the Acacia and dead shrubs to be indicators...... of parasite populations. We find evidence that the root hemiparasitic shrubs, like herbaceous root hemiparasites, prefer growing at distances from neighbouring plants that fulfil resource requirements both below-ground and above-ground. Assuming that root hemiparasites are limited by their hosts, we present...

Comparative wood anatomy of some shrubs native to the Northern Rocky Mountains

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Arlene Dale

1968-01-01

This paper describes some xylem characteristics of the more important shrub species of the Northern Rockies and presents a key for identifying shrub-wood specimens by microscopic characters. The paper contains photomicrographs of 55 shrub woods.

Holocene Vegetation Succession and Response to Climate Change on the South Bank of the Heilongjiang-Amur River, Mohe County, Northeast China

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Chao Zhao

2016-01-01

Full Text Available Pollen samples from peat sediments on the south bank of the Heilongjiang River in northern Northeast China (NE China were analyzed to reconstruct the historical response of vegetation to climate change since 7800 cal yr BP. Vegetation was found to have experienced five successions from cold-temperate mixed coniferous and broadleaved forest to forest-steppe, steppe-woodland, steppe, and finally meadow-woodland. From 7800 to 7300 cal yr BP, the study area was warmer than present, and Betula, Larix, and Picea-dominated mixed coniferous and broadleaved forests thrived. Two cooling events at 7300 cal yr BP and 4500 cal yr BP led to a decrease in Betula and other broadleaved forests, whereas herbs of Poaceae expanded, leading to forest-steppe and then steppe-woodland environments. After 2500 cal yr BP, reduced temperatures and a decrease in evaporation rates are likely to have resulted in permafrost expansion and surface ponding, with meadow and isolated coniferous forests developing a resistance to the cold-wet environment. The Holocene warm period in NE China (7800–7300 cal yr BP could have resulted in a strengthening of precipitation in northernmost NE China and encouraged the development of broadleaved forests.

The effect of polyethylene glycol on intake of Mediterranean shrubs by sheep and goats.

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Rogosic, J; Pfister, J A; Provenza, F D; Pavlicevic, J

2008-12-01

Poor nutritional quality and increased content of secondary compounds can reduce consumption of Mediterranean shrubs by herbivores. In 2 sequential trials, we examined the effect of polyethylene glycol (PEG) and number of shrub species offered on daily intake of Mediterranean shrubs by 12 sheep and 12 goats. The PEG (25 g) was fed to experimental animals with barley. In trial 1 (6 shrubs), goats ate more (P = 0.0008) daily total shrub biomass than did sheep (60.7 vs. 45.9 +/- 2.6 g/kg of BW). There was a trend (P = 0.08) toward a positive PEG effect on total shrub intake, with PEG-supplemented animals consuming more total shrubs than controls (56.7 vs. 50.0 +/- 2.6 g/kg of BW). Trial 2 (using 3 shrubs) was a continuation of trial 1, except that animals were given less barley and treatment animals were given more PEG (50 g). Both sheep and goats showed a numerical decrease in total shrub intake from trial 1 to trial 2. Sheep receiving PEG ate more (P = 0.002) total shrubs than did controls, but no PEG effect was found for goats. Thus, PEG had a greater influence on sheep than goats when only 3 shrubs were offered, a result that may be related to the fact that fewer shrubs with complementary secondary compounds were offered and that goats appear to have a greater ability to consume and detoxify secondary compounds from Mediterranean shrubs. Overall, as the number and diversity of shrubs offered increased, supplemental PEG had less effect on increasing intake for both goats and sheep.

Co-occurring nonnative woody shrubs have additive and non-additive soil legacies

DEFF Research Database (Denmark)

Kuebbing, Sara E.; Patterson, Courtney M.; Classen, Aimee Taylor

2016-01-01

shrubs, Lonicera maackii and Ligustrum sinense, in deciduous forests of the southeastern United States. We measured the performance of each nonnative shrub, a native herbaceous community, and a nonnative woody vine in soils conditioned by each shrub singly or together in polyculture. Soils conditioned...... by both nonnative shrubs had non-additive impacts on native and nonnative performance. Root mass of the native herbaceous community was 1.5 times lower and the root mass of the nonnative L. sinense was 1.8 times higher in soils conditioned by both L. maackii and L. sinense than expected based upon growth...... in soils conditioned by either shrub singly. This result indicates that when these two nonnative shrubs co-occur, their influence on soils disproportionally favors persistence of the nonnative L. sinense relative to this native herbaceous community, and could provide an explanation of why native species...

Facilitating the afforestation of Mediterranean polluted soils by nurse shrubs.

Science.gov (United States)

Domínguez, María T; Pérez-Ramos, Ignacio M; Murillo, José M; Marañón, Teodoro

2015-09-15

The revegetation of polluted sites and abandoned agricultural soils is critical to reduce soil losses and to control the spread of soil pollution in the Mediterranean region, which is currently exposed to the greatest soil erosion risk in Europe. However, events of massive plant mortality usually occur during the first years after planting, mainly due to the adverse conditions of high irradiance and drought stress. Here, we evaluated the usefulness of considering the positive plant-plant interactions (facilitation effect) in the afforestation of polluted agricultural sites, using pre-existing shrubs as nurse plants. We used nurse shrubs as planting microsites for acorns of Quercus ilex (Holm oak) along a gradient of soil pollution in southwestern Spain, and monitored seedling growth, survival, and chemical composition during three consecutive years. Seedling survival greatly increased (from 20% to more than 50%) when acorns were sown under shrub, in comparison to the open, unprotected matrix. Facilitation of seedling growth by shrubs increased along the gradient of soil pollution, in agreement with the stress gradient hypothesis that predicts higher intensity of the facilitation effects with increasing abiotic stress. Although the accumulation of trace elements in seedling leaves was higher underneath shrub, the shading conditions provided by the shrub canopy allowed seedlings to cope with the toxicity provoked by the concurrence of low pH and high trace element concentrations in the most polluted sites. Our results show that the use of shrubs as nurse plants is a promising tool for the cost-effective afforestation of polluted lands under Mediterranean conditions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Late Glacial to Holocene environments in the present-day coldest region of the Northern Hemisphere inferred from a pollen record of Lake Billyakh, Verkhoyansk Mts, NE Siberia

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S. Müller

2009-03-01

Full Text Available In this study, a radiocarbon-dated pollen record from Lake Billyakh (65°17' N, 126°47' E; 340 m a.s.l. in the Verkhoyansk Mountains was used to reconstruct vegetation and climate change since about 15 kyr BP. The pollen record and pollen-based biome reconstruction suggest that open cool steppe (STEP and grass and sedge tundra (TUND communities with Poaceae, Cyperaceae, Artemisia, Chenopodiaceae, Caryophyllaceae and Selaginella rupestris dominated the area from 15 to 13.5 kyr BP. On the other hand, the constant presence of Larix pollen in quantities comparable to today's values points to the constant presence of boreal deciduous conifer (CLDE trees in the regional vegetation during the Late Glacial. A major spread of shrub tundra communities, including birch (Betula sect. Nanae, alder (Duschekia fruticosa and willow (Salix species, is dated to 13.5–12.7 kyr BP, indicating a noticeable increase in precipitation toward the end of the Last Glaciation, particularly during the Bølling-Allerød Interstadial. Between 12.7 and 11.4 kyr BP pollen percentages of herbaceous taxa rapidly increased, whereas shrub taxa percentages decreased, suggesting strengthening of the steppe communities associated with the relatively cold and dry Younger Dryas Stadial. However, the pollen data in hand indicate that Younger Dryas climate was less severe than the climate during the earlier interval from 15 to 13.5 kyr BP. The onset of the Holocene is marked in the pollen record by the highest values of shrub and lowest values of herbaceous taxa, suggesting a return of warmer and wetter conditions after 11.4 kyr BP. Percentages of tree taxa increase gradually and reach maximum values after 7 kyr BP, reflecting the spread of boreal cold deciduous and taiga forests in the region. An interval between 7 and 2 kyr BP is noticeable for the highest percentages of Scots pine (Pinus subgen.

Shrub expansion in SW Greenland under modest regional warming

DEFF Research Database (Denmark)

Jørgensen, Rasmus Halfdan; Meilby, Henrik; Kollmann, Johannes

2013-01-01

Shrub expansion has been observed widely in tundra areas across the Arctic. This phenomenon has been partially attributed to increasing temperatures over the past century. However, relationships among shrub expansion, grazing, and human disturbance have been studied little. SW Greenland...... is a subarctic to low-arctic region with a long and complex land-use history and only modest temperature increases over the past 50 years (0.2 °C decade-1), but changes in shrub cover have not previously been studied in this region. We compiled historical photographs of vegetation in SW Greenland (1898......–1974) and repeated the photos in 2010 and 2011. Sixty-four photo pairs were cropped into 133 smaller units and classified by aspect, substrate stability, muskoxen grazing, and human disturbance. The photo material was evaluated by 22 experts with respect to changes in shrub cover, revealing a general increase across...

Effect of desertification on productivity in a desert steppe.

Science.gov (United States)

Tang, Zhuangsheng; An, Hui; Deng, Lei; Wang, Yingying; Zhu, Guangyu; Shangguan, Zhouping

2016-06-14

Desertification, one of the most severe types of land degradation in the world, is of great importance because it is occurring, to some degree, on approximately 40% of the global land area and is affecting more than 1 billion people. In this study, we used a space-for-time method to quantify the impact of five different desertification regimes (potential (PD), light (LD), moderate (MD), severe (SD), and very severe (VSD)) on a desert steppe ecosystem in northern China to examine the relationship between the productivity of the vegetation and soil properties and to determine the mechanism underlying the effects of desertification on productivity. Our results showed that the effects of desertification on TP (total phosphorus) and AP (available phosphorus) were not significant, and desertification decreased productivity in the desert steppe as a result of direct changes to soil physical properties, which can directly affect soil chemical properties. Therefore, intensive grassland management to improve soil quality may result in the long-term preservation of ecosystem functions and services.

Ecology and Conservation of Steppes and Semi-Natural Grasslands

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Valkó Orsolya

2016-12-01

Full Text Available Palaearctic grasslands encompass a diverse variety of habitats, many of high nature value and vulnerability. The main challenges are climate-change, land-use change, agricultural intensification and abandonment. Many measures are in place to address these challenges, through restoration and appropriate management, though more work is necessary. We present eight studies from China/Germany, Greece, Kazakhstan, Russia and Ukraine. The papers cover a wide range of grassland and steppe habitats and cover vegetation ecology, syntaxonomy and zoology. We also conducted a systematic search on steppe and grassland diversity. The greatest number of studies was from China, followed by Germany and England. We conclude that the amount of research being carried out on Eurasian grasslands is inadequate considering their high levels of biodiversity and vulnerability. We hope to encourage readers to address current major challenges, such as how to manage grasslands for the benefit of diverse taxa, to ensure that conservation initiatives concentrate on sites where there is good potential for success and for the generation of realistic and viable conservation strategies.

Diet Switching by Mammalian Herbivores in Response to Exotic Grass Invasion.

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Carolina Bremm

Full Text Available Invasion by exotic grasses is a severe threat to the integrity of grassland ecosystems all over the world. Because grasslands are typically grazed by livestock and wildlife, the invasion is a community process modulated by herbivory. We hypothesized that the invasion of native South American grasslands by Eragrostis plana Nees, an exotic tussock-forming grass from Africa, could be deterred by grazing if grazers switched dietary preferences and included the invasive grass as a large proportion of their diets. Bos taurus (heifers and Ovis aries (ewes grazed plots with varying degrees of invasion by E. plana in a replicated manipulative experiment. Animal positions and species grazed were observed every minute in 45-min grazing session. Proportion of bites and steps in and out of E. plana tussocks were measured and used to calculate several indices of selectivity. Both heifers and ewes exhibited increasing probability of grazing E. plana as the proportion of area covered by tussocks increased, but they behaved differently. In agreement with expectations based on the allometry of dietary preferences and morphology, ewes consumed a low proportion of E. plana, except in areas that had more than 90% E. plana cover. Heifers consumed proportionally more E. plana than ewes. Contrary to our hypothesis, herbivores did not exhibit dietary switching towards the invasive grass. Moreover, they exhibited avoidance of the invasive grass and preference for short-statured native species, both of which should tend to enhance invasion. Unless invasive plants are highly palatable to livestock, the effect of grazing to deter the invasion is limited, due to the inherent avoidance of the invasive grass by the main grazers in the ecosystem, particularly sheep.

Guanaco’s diet and forage preferences in Nothofagus forest environments of Tierra del Fuego, Argentina

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Quinteros, C.P.; Bava, J.; Gobbi, M.E.; Defossé, G.E.

2017-11-01

Aim of study: Guanaco (Lama guanicoe Müller), is a South American native ungulate widely distributed in Patagonia, which in the island of Tierra del Fuego (TF), extends its habitat into Nothofagus spp. forests. Within these forests, guanacos consume lenga (Nothofagus pumilio) leaves and twigs, and other understory species. The aim of this work was to determine: 1) the spring and summer diet of free ranging guanacos, and 2) which plants, grown in the forest understory, guanacos do prefer, or avoid, in these seasons of great forage abundance. Area of study: Tierra del Fuego (Argentina), on three representative areas which combined Nothofagus forests and adjacent meadows (vegas). Material and Methods: uanacos’ diet was determined by comparing epidermal and non-epidermal plant fragments with micro-histological analyses of feces. The analysis was made from composite samples of fresh feces, collected at the seasons of maximum forage productivity (spring and summer). Main results: During spring, 48% of guanacos’ diet was composed of lenga leaves, 30% of grass-like species, 15% of grasses, and less than 7% of herbs, shrubs, and lichens. In summer, 40% of the diet was composed of grasses, 30% of lenga leaves, 25% of grass-like species and the rest corresponded to herbs, shrubs, and lichens. Within the forest understory, guanaco selected lenga leaves and twigs, grass species were consumed according to their availability (or sometimes rejected), while other herbs were not consumed at all. Research highlights: Guanacos’ consumption preference for lenga, even considering the high availability of other forages, could adversely affect forest regeneration.

Guanaco’s diet and forage preferences in Nothofagus forest environments of Tierra del Fuego, Argentina

International Nuclear Information System (INIS)

Quinteros, C.P.; Bava, J.; Gobbi, M.E.; Defossé, G.E.

2017-01-01

Aim of study: Guanaco (Lama guanicoe Müller), is a South American native ungulate widely distributed in Patagonia, which in the island of Tierra del Fuego (TF), extends its habitat into Nothofagus spp. forests. Within these forests, guanacos consume lenga (Nothofagus pumilio) leaves and twigs, and other understory species. The aim of this work was to determine: 1) the spring and summer diet of free ranging guanacos, and 2) which plants, grown in the forest understory, guanacos do prefer, or avoid, in these seasons of great forage abundance. Area of study: Tierra del Fuego (Argentina), on three representative areas which combined Nothofagus forests and adjacent meadows (vegas). Material and Methods: uanacos’ diet was determined by comparing epidermal and non-epidermal plant fragments with micro-histological analyses of feces. The analysis was made from composite samples of fresh feces, collected at the seasons of maximum forage productivity (spring and summer). Main results: During spring, 48% of guanacos’ diet was composed of lenga leaves, 30% of grass-like species, 15% of grasses, and less than 7% of herbs, shrubs, and lichens. In summer, 40% of the diet was composed of grasses, 30% of lenga leaves, 25% of grass-like species and the rest corresponded to herbs, shrubs, and lichens. Within the forest understory, guanaco selected lenga leaves and twigs, grass species were consumed according to their availability (or sometimes rejected), while other herbs were not consumed at all. Research highlights: Guanacos’ consumption preference for lenga, even considering the high availability of other forages, could adversely affect forest regeneration.

Shrubs of California's chaparral, timberland, and wood land: area, ownership, and stand characteristics.

Science.gov (United States)

Charles L. Boisinger

1988-01-01

A statewide inventory of shrubs in chaparral and on timberland and woodland in California is presented, and the relevance of shrubs to resource management is discussed. Shrub types (excluding coastal sage and Great Basin and desert shrubs) cover about 10 million acres, 73 percent of which is chaparral. Chamise is the most widespread type in chaparral (51 percent of...

[Recent fauna of ground-nesting birds in Transvolga steppes and its dynamics in the 20th century].

Science.gov (United States)

Oparin, M L

2008-01-01

It is shown that the structure of the ground-nesting bird fauna in Transvolga steppes has changed during the 20th century. The complex of lark species characteristic of true and dry steppe has disappeared because of climate change and impact of economic activity (the establishment of windbreak and roadside forest strips), which has provided for a sharp increase in the abundance of corvid birds.

Characterization of a sagebrush (Artemisia tridentata ssp. wyomingensis) die-off on the Handford Site

International Nuclear Information System (INIS)

Cardenas, A.; Lewinsohn, J.; Auger, C.; Downs, J.L.; Cadwell, L.L.; Burrows, R.

1997-09-01

The Hanford Site contains one of the few remaining contiguous areas of shrub-steppe habitat left in Washington State. This habitat is home to many native plant and wildlife species, some of which are threatened with extinction or are unique to the Site. The importance of the Hanford Site increases as other lands surrounding the Site are developed, and these native species and habitats are lost. Stands of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) on the Site are a particularly important component of shrub-steppe habitat, because a number of wildlife require big sagebrush for food and cover. Since 1993, researchers and field biologists have made anecdotal observations of dying and declining sagebrush in stands of shrubs near the 100 Areas. This study was initiated to delineate and document the general boundary where sagebrush stands appear to be declining. We mapped the areal extent of the die-off using a global positioning system and found that the central portion of the die-off encompasses 280 hectares. Shrub stand defoliation was estimated to be near or greater than 80% in this area. The remainder of the die-off area exhibits varying mixtures of completely defoliated, partially defoliated, and healthy-looking stands. Declining sagebrush stands comprise a total of 1776 hectares

Characterization of a sagebrush (Artemisia tridentata ssp. wyomingensis) die-off on the Handford Site

Energy Technology Data Exchange (ETDEWEB)

Cardenas, A.; Lewinsohn, J.; Auger, C.; Downs, J.L.; Cadwell, L.L.; Burrows, R.

1997-09-01

The Hanford Site contains one of the few remaining contiguous areas of shrub-steppe habitat left in Washington State. This habitat is home to many native plant and wildlife species, some of which are threatened with extinction or are unique to the Site. The importance of the Hanford Site increases as other lands surrounding the Site are developed, and these native species and habitats are lost. Stands of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) on the Site are a particularly important component of shrub-steppe habitat, because a number of wildlife require big sagebrush for food and cover. Since 1993, researchers and field biologists have made anecdotal observations of dying and declining sagebrush in stands of shrubs near the 100 Areas. This study was initiated to delineate and document the general boundary where sagebrush stands appear to be declining. We mapped the areal extent of the die-off using a global positioning system and found that the central portion of the die-off encompasses 280 hectares. Shrub stand defoliation was estimated to be near or greater than 80% in this area. The remainder of the die-off area exhibits varying mixtures of completely defoliated, partially defoliated, and healthy-looking stands. Declining sagebrush stands comprise a total of 1776 hectares.

Improving Interdisciplinary Relationships in Primary Care with the Implementation of TeamSTEPPS

Directory of Open Access Journals (Sweden)

Nicole Siddons

2016-03-01

Full Text Available A major challenge in healthcare is lack of interdisciplinary collaboration (O’Daniel & Rosenstein, 2008. The Institute of Medicine report, To Err is Human: Building a Safer Health System (1999, shows that errors often occur due to lapses in partnership and communication. This article describes the implementation of TeamSTEPPS, an evidence-based tool for optimizing staff relationships and partnership, in a clinic in which a change in the care model had affected interprofessional collaboration and teamwork, threatening healthcare outcomes and staff engagement. The implementation of TeamSTEPPS, customized using elements of IDEO’s (2015 Human-Centered Design, shifted the culture of the clinic towards partnership, resulting in improved staff perceptions of teamwork and statistically significant improvements in the quality of patient care.

Mammalian herbivores confer resilience of Arctic shrub-dominated ecosystems to changing climate.

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Kaarlejärvi, Elina; Hoset, Katrine S; Olofsson, Johan

2015-09-01

Climate change is resulting in a rapid expansion of shrubs in the Arctic. This expansion has been shown to be reinforced by positive feedbacks, and it could thus set the ecosystem on a trajectory toward an alternate, more productive regime. Herbivores, on the other hand, are known to counteract the effects of simultaneous climate warming on shrub biomass. However, little is known about the impact of herbivores on resilience of these ecosystems, that is, the capacity of a system to absorb disturbance and still remain in the same regime, retaining the same function, structure, and feedbacks. Here, we investigated how herbivores affect resilience of shrub-dominated systems to warming by studying the change of shrub biomass after a cessation of long-term experimental warming in a forest-tundra ecotone. As predicted, warming increased the biomass of shrubs, and in the absence of herbivores, shrub biomass in tundra continued to increase 4 years after cessation of the artificial warming, indicating that positive effects of warming on plant growth may persist even over a subsequent colder period. Herbivores contributed to the resilience of these systems by returning them back to the original low-biomass regime in both forest and tundra habitats. These results support the prediction that higher shrub biomass triggers positive feedbacks on soil processes and microclimate, which enable maintaining the rapid shrub growth even in colder climates. Furthermore, the results show that in our system, herbivores facilitate the resilience of shrub-dominated ecosystems to climate warming. © 2015 John Wiley & Sons Ltd.

Bird communities of the arctic shrub tundra of Yamal: habitat specialists and generalists.

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Vasiliy Sokolov

Full Text Available BACKGROUND: The ratio of habitat generalists to specialists in birds has been suggested as a good indicator of ecosystem changes due to e.g. climate change and other anthropogenic perturbations. Most studies focusing on this functional component of biodiversity originate, however, from temperate regions. The Eurasian Arctic tundra is currently experiencing an unprecedented combination of climate change, change in grazing pressure by domestic reindeer and growing human activity. METHODOLOGY/PRINCIPAL FINDINGS: Here we monitored bird communities in a tundra landscape harbouring shrub and open habitats in order to analyse bird habitat relationships and quantify habitat specialization. We used ordination methods to analyse habitat associations and estimated the proportions of specialists in each of the main habitats. Correspondence Analysis identified three main bird communities, inhabiting upland, lowland and dense willow shrubs. We documented a stable structure of communities despite large multiannual variations of bird density (from 90 to 175 pairs/km(2. Willow shrub thickets were a hotspot for bird density, but not for species richness. The thickets hosted many specialized species whose main distribution area was south of the tundra. CONCLUSION/SIGNIFICANCE: If current arctic changes result in a shrubification of the landscape as many studies suggested, we would expect an increase in the overall bird abundance together with an increase of local specialists, since they are associated with willow thickets. The majority of these species have a southern origin and their increase in abundance would represent a strengthening of the boreal component in the southern tundra, perhaps at the expense of species typical of the subarctic zone, which appear to be generalists within this zone.

Impact of Climate Change and Anthropogenic Activities in the Dynamics of Land Cover in Mediterranean Steppe West Algeria

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Si Tayeb, Tayeb

2016-08-01

The last thirty years, there is a real dynamic change of land cover with intensive degradation of the natural vegetation especially in arid zone. Indeed, the adverse effects of drought periods from the year 1970 combined with population growth and economic conditions experienced by the country in the 1980s have greatly upset the delicate balance of the natural environment. These adverse effects may result in partial or total disappearance of some natural ecosystems.The objective of this work is to study the distribution of plant formations that constitute the ecosystem typical of west Algeria and their dynamics in time and space, as well as to develop a method to monitor the degradation process and a system capable of effectively protecting areas classified for their plant and animal species.The Landsat satellite images were used to map the vegetation of the study area at a scale of 1:200,000. A comparison was then made between the map obtained from satellite images (Landsat 8) of 2014 and (Landsat 5) of 1987.The results show the following main trends in the distribution patterns of steppe species, a strong decrease of land occupied by steppe of Stipatenacissima and steppe of Artimesiaherba-alba, witch replaced by three taxa Thymelaeamicrophylla, Salsolavermiculata and Peganumharmala. Steppe of Artemisia herbaalba has been transformed by steppe of. taxa Thymelaeamicrophylla, Salsolavermiculata and Lygeumspartum. Woody species such as Quercus ilex and Juniperusphoenicea are characterized by a large regression.

Mediterranean shrub diversity and its effect on food intake in goats

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Tomislav Šarić

2014-07-01

Full Text Available Mediterranean ecosystem offers a variety of shrubs that were over long periods of time involved in the evolution of complex plant-animal interactions. Biochemical components of these plants enter different metabolic pathways after digestion and absorption, resulting in development of dietary preferences in browsing animals. Herbivores in general were found to perform better when grazing in a mixed plant community composed of diverse species, and show preferential feeding behaviours for mixed vs single species diet. Our findings demonstrate an asymptotic relationship among Mediterranean shrubs species diversity and their voluntary intake by goats. Shrub biomass intake showed linear increase when number of different shrubs in diet increased from one to three. However, goats did not further increase intake when the number of shrub species increased from four to eight. As the number of shrub species offered increased, goats exhibited more preferential feeding behaviour for Quercus pubescens, Fraxinus ornus, Rubus heteromorphus and Arbutus unedo and decreased the intake of Hedera helix, Juniperus oxycedrus and Helichrysum italicum. This asymptotic relationship indicates that the maintenance of plant species richness in Mediterranean shrublands can overall benefit domestic goat farming, goat’s productive performance, and the conservation of plant biodiversity.

On the influence of shrub height and expansion on northern high latitude climate

International Nuclear Information System (INIS)

Bonfils, C J W; Phillips, T J; Cameron-Smith, P; Lawrence, D M; Riley, W J; Subin, Z M

2012-01-01

There is a growing body of empirical evidence documenting the expansion of shrub vegetation in the circumpolar Arctic in response to climate change. Here, we conduct a series of idealized experiments with the Community Climate System Model to analyze the potential impact on boreal climate of a large-scale tundra-to-shrub conversion. The model responds to an increase in shrub abundance with substantial atmospheric heating arising from two seasonal land–atmosphere feedbacks: a decrease in surface albedo and an evapotranspiration-induced increase in atmospheric moisture content. We demonstrate that the strength and timing of these feedbacks are sensitive to shrub height and the time at which branches and leaves protrude above the snow. Taller and aerodynamically rougher shrubs lower the albedo earlier in the spring and transpire more efficiently than shorter shrubs. These mechanisms increase, in turn, the strength of the indirect sea-ice albedo and ocean evaporation feedbacks contributing to additional regional warming. Finally, we find that an invasion of tall shrubs tends to systematically warm the soil, deepen the active layer, and destabilize the permafrost (with increased formation of taliks under a future scenario) more substantially than an invasion of short shrubs. (letter)

[Allelopathic effects of Artemisia sacrorum population in typical steppe based on niche theory].

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Wang, Hui; Xie, Yong-Sheng; Cheng, Ji-Min; She, Xiao-Yan

2012-03-01

By using modified Levins niche width index and Pianka niche overlap index, this paper analyzed the ecological competition between constructive and dominant species in a typical steppe. The stem- and leaf extracts from the constructive species (Artemisia sacrorum) were utilized to study their allelopathic potential on the seed germination and plant growth of the dominant species (Stipa bungeana, Thymus mongolicus, S. grandis, and Leymus secalinus), and the ecological position of A. sacrorum in the steppe succession. In the steppe, S. bungeana had the widest niche width (0.99), followed by T. mongolicus (0.94), A. sacrorum (0.82), S. grandis (0.76), and L. secalinus (0.73). The niche overlap value between A. sacrorum and S. bungeana, S. bungeana and T. mongolicus, T. mongolicus and S. grandis, and A. sacrorum and T. mongolicus was 0.90, 0.95, 0.94, and 0.86, respectively. The allelopathic effects of A. sacrorum extracts varied with their concentration. For the seed germination, root growth, and shoot growth of the dominant species, A. sacrorum extracts showed a trend of promoting at low concentrations and inhibiting at high concentrations. The extracts of A. sacrorum had a stronger promotion effect on the root growth of S. bungeana than on that of T. mongolicus, but a stronger inhibition effect on the shoot growth of T. mongolicus than on that of S. bungeana. Methanol extracts had stronger allelopathic effects than aqueous extracts. The high niche overlap between A. sacrorum and S. bungeana, and T. mongolicus and S. grandis indicated that the steppe community would continue succession to S. bungeana, while A. sacrorum population was only an important transitional stage during the succession. The allelopathic effect of A. sacrorum played a driving role in the succession process.

Spatio-temporal patterns of ptarmigan occupancy relative to shrub cover in the Arctic

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Schmutz, Joel A.

2014-01-01

Rock and willow ptarmigan are abundant herbivores that require shrub habitats in arctic and alpine areas. Shrub expansion is likely to increase winter habitat availability for ptarmigan, which in turn influence shrub architecture and growth through browsing. Despite their ecological role in the Arctic, the distribution and movement patterns of ptarmigan are not well known, particularly in northern Alaska where shrub expansion is occurring. We used multi-season occupancy models to test whether ptarmigan occupancy varied within and among years, and the degree to which colonization and extinction probabilities were related to shrub cover and latitude. Aerial surveys were conducted from March to May in 2011 and April to May 2012 in a 21,230 km2 area in northeastern Alaska. In areas with at least 30 % shrub cover, the probability of colonization by ptarmigan was >0.90, indicating that moderate to extensive patches of shrubs (typically associated with riparian areas) had a high probability of becoming occupied by ptarmigan. Occupancy increased throughout the spring in both years, providing evidence that ptarmigan migrated from southern wintering areas to breeding areas north of the Brooks Range. Occupancy was higher in the moderate snow year than the high snow year, and this was likely due to higher shrub cover in the moderate snow year. Ptarmigan distribution and migration in the Arctic are linked to expanding shrub communities on a wide geographic scale, and these relationships may be shaping ptarmigan population dynamics, as well as rates and patterns of shrub expansion.

Spatio-temporal dynamics of arbuscular mycorrhizal fungi associated with glomalin-related soil protein and soil enzymes in different managed semiarid steppes.

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Wang, Qi; Bao, Yuying; Liu, Xiaowei; Du, Guoxin

2014-10-01

Temporal and spatial patterns of arbuscular mycorrhizal fungi (AMF) and glomalin and soil enzyme activities were investigated in different managed semiarid steppes located in Inner Mongolia, North China. Soils were sampled in a depth up to 30 cm from non-grazed, overgrazed, and naturally restored steppes from June to September. Roots of Leymus chinense (Trin.) Tzvel. and Stipagrandis P. Smirn. were also collected over the same period. Results showed that overgrazing significantly decreased the total mycorrhizal colonization of S. grandis; total colonization of L. chinensis roots was not significantly different in the three managed steppes. Nineteen AMF species belonging to six genera were isolated. Funneliformis and Glomus were dominant genera in all three steppes. Spore density and species richness were mainly influenced by an interaction between plant growth stage and management system (P soil depth. AMF species richness was significantly positively correlated with soil acid phosphatase activity, alkaline phosphatase activity, and two Bradford-reactive soil protein (BRSP) fractions (P soil glomalin and phosphatase activity in different managed semiarid steppes. Based on these observations, AMF communities could be useful indicators for evaluating soil quality and function of semiarid grassland ecosystems.

Fire rehabilitation effectiveness: a chronosequence approach for the Great Basin

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Pyke, David A.; Pilliod, David S.; Chambers, Jeanne C.; Brooks, Matthew L.; Grace, James

2009-01-01

these sites, 61 were seeded by using a drill, 27 were broadcast aerially, and 12 had a combination of both. We randomly sampled three burned and seeded, burned and unseeded, and unburned and unseeded locations in the vicinity of the fire, each within the same ecological site. We measured foliar cover of all plant functional groups (perennial or annual, shrub, grass, forb, native or introduced), biological soil crusts, and abiotic (bare soil and litter) variables using the line-point intercept protocol. Fuel loads and horizontal fuel continuity were measured. We applied linear mixed models to response variables (cover and density of plant groups) relative to the dependent variables (seeding treatments and precipitation/temperature relationships. Post-fire strengths with native perennial grasses or shrubs in mixes did not increase density or cover of these groups significantly relative to unseeded, burned areas. Seeded non-native perennial grasses and the shrub Bassia prostrata were effective in providing more cover in aerial and drill seedings. Seeded non-native perennial grass cover increased with increased annual precipitation regardless of seeding type. Seeding native shrubs, particularly Artemisia tridentata, did not significantly increase shrub cover in burned areas. Cover of undesirable non-native annual grasses was lower in drill seedings relative to unseeded areas but only at higher elevations. Seeding effectiveness after wildfire is unpredictable in drier, low elevation environments, and our findings indicate management objectives are more likely met when focusing efforts on higher elevation or higher precipitation locations where establishment of perennial grasses is more likely. On sites where potential for invasion and dominance of non-native annuals is high, such as lower and drier sites, intensive methods of restoration that include invasive plant control before seeding may be required. Where establishment of native perennial plants is the goal, managers

Can shrubs help to reconstruct historical glacier retreats?

International Nuclear Information System (INIS)

Buras, Allan; Hallinger, Martin; Wilmking, Martin

2012-01-01

In the 21st century, most of the world’s glaciers are expected to retreat due to further global warming. The range of this predicted retreat varies widely as a result of uncertainties in climate and glacier models. To calibrate and validate glacier models, past records of glacier mass balance are necessary, which often only span several decades. Long-term reconstructions of glacier mass balance could increase the precision of glacier models by providing the required calibration data. Here we show the possibility of applying shrub growth increments as an on-site proxy for glacier summer mass balance, exemplified by Salix shrubs in Finse, Norway. We further discuss the challenges which this method needs to meet and address the high potential of shrub growth increments for reconstructing glacier summer mass balance in remote areas. (letter)

Rooting depth varies differentially in trees and grasses as a function of mean annual rainfall in an African savanna.

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Holdo, Ricardo M; Nippert, Jesse B; Mack, Michelle C

2018-01-01

A significant fraction of the terrestrial biosphere comprises biomes containing tree-grass mixtures. Forecasting vegetation dynamics in these environments requires a thorough understanding of how trees and grasses use and compete for key belowground resources. There is disagreement about the extent to which tree-grass vertical root separation occurs in these ecosystems, how this overlap varies across large-scale environmental gradients, and what these rooting differences imply for water resource availability and tree-grass competition and coexistence. To assess the extent of tree-grass rooting overlap and how tree and grass rooting patterns vary across resource gradients, we examined landscape-level patterns of tree and grass functional rooting depth along a mean annual precipitation (MAP) gradient extending from ~ 450 to ~ 750 mm year -1 in Kruger National Park, South Africa. We used stable isotopes from soil and stem water to make inferences about relative differences in rooting depth between these two functional groups. We found clear differences in rooting depth between grasses and trees across the MAP gradient, with grasses generally exhibiting shallower rooting profiles than trees. We also found that trees tended to become more shallow-rooted as a function of MAP, to the point that trees and grasses largely overlapped in terms of rooting depth at the wettest sites. Our results reconcile previously conflicting evidence for rooting overlap in this system, and have important implications for understanding tree-grass dynamics under altered precipitation scenarios.

Combined effects of rainfall regime and plot length on runoff and soil loss in the Loess Plateau of China

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Liu, J.; Gao, G.; Wang, S.; Fu, B.

2017-12-01

The purpose of this paper was to study the interaction effects of rainfall regime and slope length on runoff and soil loss under different land uses. Event runoff and soil loss of forest, shrub and grass were measured in plots with length of 5, 9, or 13 m in the Loess Plateau from 2008 to 2016. Fifty-nine erosive rainfall events were recorded and classified into three rainfall regimes. The results firstly showed that the runoff coefficient was grass > shrub > forest, and soil loss was grass > forest > shrub, but the differences between forest and shrub in runoff and between grass and forest in soil loss didn't reach significant level. Secondly, rainfall regimes had important effect on runoff and soil loss of different land uses. The lowest runoff coefficients and the highest soil loss in regime 2 were found in shrub and forest land, respectively, which differed from that of regime 1. In total, rainfall regime 1 had the highest runoff coefficient of 0.84-2.06%, followed by regime 3 with 0.33-0.88%, and regime 2 with 0.04-0.06%. Soil loss in forest and grass land had a different order of regime 3 > regime 1 > regime 2. Thirdly, both the runoff coefficient and soil loss decreased with increasing plot length, while the effect of slope length on runoff/soil loss were influenced by land use type and rainfall regimes.

Role of species diversity and secondary compound complementarity on diet selection of Mediterranean shrubs by goats.

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Rogosic, Jozo; Estell, Richard E; Skobic, Dragan; Martinovic, Anita; Maric, Stanislava

2006-06-01

Goats foraging on Mediterranean shrubs containing secondary compounds (toxins) may consume a variety of shrubs that contain different phytotoxins, thereby increasing shrub intake and avoiding toxicosis. We conducted eight experiments to examine whether goats offered different mixtures of shrubs containing different phytotoxins (tannins and saponins) would consume more shrub biomass than goats offered one shrub a single phytotoxin (tannin or saponin). In the first three experiments, goats fed a mixture of three tannin-rich shrubs (Quercus ilex, Arbutus unedo, and Pistacia lentiscus) ate more foliage than goats offered only one shrub (23.2 vs. 10.7 g/kg BW; 25.2 vs. 13.4 g/kg BW, and 27.9 vs. 7.9 g/kg BW), regardless of tannin concentration in individual shrub species. Goats also consumed more foliage when offered the same three tannin-rich shrubs than when offered the saponin-rich shrub Hedera helix (25.4 vs. 8.0 g/kg BW). However, goats offered a mixture of the same three tannin-rich shrubs consumed less foliage than goats offered a mixture of two shrubs containing tannins and saponins: Quercus and Hedera (21.6 vs. 27.1 g/kg BW), Arbutus and Hedera (21.8 vs. 27.1 g/kg BW), and Pistacia and Hedera (19.7 vs. 22.0 g/kg BW). Comparison of intake of shrubs containing only tannins or saponins to intake of shrubs containing both tannins and saponins indicated that goats consumed more total biomass when fed with shrubs with both classes of compounds than with either tannins or saponins alone. Our results suggest that goats can increase intake of Mediterranean shrubs high in secondary compounds by selecting those with different classes of phytotoxins. Simultaneous ingestion of shrubs containing tannins and saponins may promote chemical interactions that inhibit toxic effects of these phytotoxins in the intestinal tract. In addition to complementary interactions between tannins and saponins, biological diversity within Mediterranean maquis vegetation also plays a positive

Do people with borderline personality disorder complicated by antisocial personality disorder benefit from the STEPPS treatment program?

Science.gov (United States)

Black, Donald W; Simsek-Duran, Fatma; Blum, Nancee; McCormick, Brett; Allen, Jeff

2016-08-01

Systems Training for Emotional Predictability and Problem Solving (STEPPS) is a group treatment for persons with borderline personality disorder (BPD). We describe results from two data sets on outcome in persons who participated in STEPPS with BPD alone or BPD plus antisocial personality disorder (ASPD). In Study 1, we examined the effect of comorbid ASPD on outcome in 65 persons with BPD who participated in a randomized controlled trial at an academic medical centre. In Study 2, we examined the effect of comorbid ASPD on outcome in 64 offenders with BPD who participated in STEPPS in correctional settings. All subjects were assessed for the presence of BPD and ASPD. In Study 1, subjects with ASPD experienced greater improvement in BPD symptoms, impulsiveness and global symptoms. In Study 2, offenders with ASPD experienced greater improvement in positive and negative behaviours and positive affectivity. We conclude that persons with BPD plus ASPD benefit from STEPPS in community and correctional settings. The findings suggest that persons with BPD plus ASPD show greater improvement in some domains than persons with BPD only. People with ASPD should not be automatically excluded from participation in the program. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

[Responses of soil fauna to environment degeneration in the process of wind erosion desertification of Hulunbeir steppe].

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Lü, Shi-Hai; Lu, Xin-Shi; Gao, Ji-Xi

2007-09-01

To reveal the relationships between soil fauna and soil environmental factors in the process of steppe desertification, field survey combined with laboratory analysis was made to study the community structure, population density and biodiversity of soil fauna, and their relationships with the changes of soil organic matter, hydrolysable nitrogen, available phosphorus and moisture contents and soil pH at different stages of desertification of Hulunbeir steppe. The soil faunal specimens collected belonged to 4 phyla, 6 classes and 12 orders. Nematoda was the only dominant group of medium- and small-sized soil fauna, occupying 94.3% of the total, while Coleoptera and Hemiptera were the dominant groups of large-sized soil fauna, with the amount of 79.7%. The group amount, population density, diversity, and evenness of soil fauna had an obvious decreasing trend with the aggravation of steppe desertification. At serious stage of desertification, soil fauna vanished completely. The population density of soil fauna in 0-20 cm soil layer had significant linear correlations with soil nutrients and moisture contents, soil pH, and litter mass, indicating that soil fauna had stronger sensibility to the changes of soil environmental factors in the process of wind erosion desertification of Hulunbeir steppe.

SQ grass sublingual allergy immunotherapy tablet for disease-modifying treatment of grass pollen allergic rhinoconjunctivitis

DEFF Research Database (Denmark)

Dahl, Ronald; Roberts, Graham; de Blic, Jacques

2016-01-01

BACKGROUND: Allergy immunotherapy is a treatment option for allergic rhinoconjunctivitis (ARC). It is unique compared with pharmacotherapy in that it modifies the immunologic pathways that elicit an allergic response. The SQ Timothy grass sublingual immunotherapy (SLIT) tablet is approved in North...... America and throughout Europe for the treatment of adults and children (≥5 years old) with grass pollen-induced ARC. OBJECTIVE: The clinical evidence for the use of SQ grass SLIT-tablet as a disease-modifying treatment for grass pollen ARC is discussed in this review. METHODS: The review included...... the suitability of SQ grass SLIT-tablet for patients with clinically relevant symptoms to multiple Pooideae grass species, single-season efficacy, safety, adherence, coseasonal initiation, and cost-effectiveness. The data from the long-term SQ grass SLIT-tablet clinical trial that evaluated a clinical effect 2...

Remote sensing data to classify functional groups of vegetation and their distribution and abundance in a semiarid mountain watershed, Idaho, USA

Science.gov (United States)

Loughridge, R. E.; Benner, S. G.; McNamara, J. P.; Flores, A. N.

2012-12-01

In water-limited montane ecosystems, topography is a significant driver of energy balance and soil moisture and therefore governs the distribution and abundance of terrestrial vegetation. Few studies have made a concerted effort to quantify spatial patterns in vegetation along physiographic gradients that control microclimate such as slope, elevation, and aspect. Furthermore, spectral mixing of different vegetation species within individual visible and near-infrared remote sensing pixels makes it difficult to constrain the temporal growth and senescence of individual plant functional types. We report on a study that seeks to understand the interacting roles of topography, soil moisture, and solar radiation on the distribution of different plant functional types within the Dry Creek Experimental Watershed (DCEW). Boise State University maintains the 27 km2 watershed which is located in the Boise Front Mountains of southwest Idaho. It is qualitatively observed in DCEW that low elevations are dominated by sage-steppe ecosystems and high elevations transition to conifer forests. It is also observed that aspect has a major control in which sage-steppe is evident at high elevations on south facing slopes conversely from north facing slopes. To quantify these trends we measured percent ground cover of functional groups (i.e. forbs, grass, shrubs, etc.) at 77 sites within DCEW spanning a large gradient in the controlling biophysiographic variables. In addition, vegetation water content (VWC) and spectral reflectance from the 325 to 1075 nm wavelengths was collected for specific vegetation types at eight permanent soil moisture monitoring sites contained in DCEW throughout the 2012 green-up/senescence transition. To develop a watershed-wide classification we built a supervised multilayer perceptron (MLP) backpropagating artificial neural network (ANN) using temporal Landsat 5 images to classify 4 major groups: sage-steppe, Douglas fir, ponderosa pine, and deciduous trees

Restoration handbook for sagebrush steppe ecosystems with emphasis on greater sage-grouse habitat - Part 3: Site level restoration decisions

Science.gov (United States)

David A. Pyke; Jeanne C. Chambers; Mike Pellant; Richard F. Miller; Jeffrey L. Beck; Paul S. Doescher; Bruce A. Roundy; Eugene W. Schupp; Steven T. Knick; Mark Brunson; James D. McIver

2017-01-01

Sagebrush steppe ecosystems in the United States currently (2016) occur on only about one-half of their historical land area because of changes in land use, urban growth, and degradation of land, including invasions of non-native plants. The existence of many animal species depends on the existence of sagebrush steppe habitat. The greater sage-grouse (Centrocercus...

Environmental Limits of Tall Shrubs in Alaska's Arctic National Parks.

Science.gov (United States)

Swanson, David K

2015-01-01

We sampled shrub canopy volume (height times area) and environmental factors (soil wetness, soil depth of thaw, soil pH, mean July air temperature, and typical date of spring snow loss) on 471 plots across five National Park Service units in northern Alaska. Our goal was to determine the environments where tall shrubs thrive and use this information to predict the location of future shrub expansion. The study area covers over 80,000 km2 and has mostly tundra vegetation. Large canopy volumes were uncommon, with volumes over 0.5 m3/m2 present on just 8% of plots. Shrub canopy volumes were highest where mean July temperatures were above 10.5°C and on weakly acid to neutral soils (pH of 6 to 7) with deep summer thaw (>80 cm) and good drainage. On many sites, flooding helped maintain favorable soil conditions for shrub growth. Canopy volumes were highest where the typical snow loss date was near 20 May; these represent sites that are neither strongly wind-scoured in the winter nor late to melt from deep snowdrifts. Individual species varied widely in the canopy volumes they attained and their response to the environmental factors. Betula sp. shrubs were the most common and quite tolerant of soil acidity, cold July temperatures, and shallow thaw depths, but they did not form high-volume canopies under these conditions. Alnus viridis formed the largest canopies and was tolerant of soil acidity down to about pH 5, but required more summer warmth (over 12°C) than the other species. The Salix species varied widely from S. pulchra, tolerant of wet and moderately acid soils, to S. alaxensis, requiring well-drained soils with near neutral pH. Nearly half of the land area in ARCN has mean July temperatures of 10.5 to 12.5°C, where 2°C of warming would bring temperatures into the range needed for all of the potential tall shrub species to form large canopies. However, limitations in the other environmental factors would probably prevent the formation of large shrub canopies

Environmental Limits of Tall Shrubs in Alaska's Arctic National Parks.

Directory of Open Access Journals (Sweden)

David K Swanson

Full Text Available We sampled shrub canopy volume (height times area and environmental factors (soil wetness, soil depth of thaw, soil pH, mean July air temperature, and typical date of spring snow loss on 471 plots across five National Park Service units in northern Alaska. Our goal was to determine the environments where tall shrubs thrive and use this information to predict the location of future shrub expansion. The study area covers over 80,000 km2 and has mostly tundra vegetation. Large canopy volumes were uncommon, with volumes over 0.5 m3/m2 present on just 8% of plots. Shrub canopy volumes were highest where mean July temperatures were above 10.5°C and on weakly acid to neutral soils (pH of 6 to 7 with deep summer thaw (>80 cm and good drainage. On many sites, flooding helped maintain favorable soil conditions for shrub growth. Canopy volumes were highest where the typical snow loss date was near 20 May; these represent sites that are neither strongly wind-scoured in the winter nor late to melt from deep snowdrifts. Individual species varied widely in the canopy volumes they attained and their response to the environmental factors. Betula sp. shrubs were the most common and quite tolerant of soil acidity, cold July temperatures, and shallow thaw depths, but they did not form high-volume canopies under these conditions. Alnus viridis formed the largest canopies and was tolerant of soil acidity down to about pH 5, but required more summer warmth (over 12°C than the other species. The Salix species varied widely from S. pulchra, tolerant of wet and moderately acid soils, to S. alaxensis, requiring well-drained soils with near neutral pH. Nearly half of the land area in ARCN has mean July temperatures of 10.5 to 12.5°C, where 2°C of warming would bring temperatures into the range needed for all of the potential tall shrub species to form large canopies. However, limitations in the other environmental factors would probably prevent the formation of large

SUPPLEMENTAL ACTIVATED CHARCOAL AND ENERGY INCREASE INTAKE OF MEDITERRANEAN SHRUBS BY SHEEP AND GOATS

Directory of Open Access Journals (Sweden)

Jozo Rogošić

2008-07-01

Full Text Available Utilization of the Mediterranean shrubby vegetation is often limited by secondary compounds, such as terpenes, which at too high concentrations can adversely affect forage intake and animal health. Ingesting compounds such as activated charcoal and energy can ameliorate the negative effects of secondary compounds and enable animals to eat more shrubs. Thus, our objectives were to determine if supplemental charcoal, energy and numbers of shrub species offered influenced intake of shrubs by sheep and goats. We conducted three experiments each with 12 lambs and 12 kids (6 activated charcoal vs. 6 controls. In the first experiment, we initially offered three shrubs (Juniperus phoenicea, Helichrysum italicum and Juniperus oxicedrus, then in the second one, two shrubs (Juniperus phoenicea and Helichrysum italicum, and finally one shrub (Juniperus phoenicea in the third experiment. In all three experiments (Exp. 1, P<0.001; Exp. 2, P < 0.0003 and Exp. 3, P < 0.03, supplemental charcoal and energy had a positive effect on total shrub intake for both lambs and kids. Kids ate more shrubs than lambs did in all three experiments (P<0.01. Regardless of experiment, both species of animals showed a numerical decrease in total shrub intake, with or without supplemental charcoal and energy, as the number of shrub species on offer decreased. Our findings support the hypothesis that biochemical diversity plays an important role in diet selection, thus enabling animals to better meet their nutritional needs and avoid toxicity.

Patterns of seed production and shrub association in two palatable ...

African Journals Online (AJOL)

Seed production and shrub association patterns of the twopalatable shrubs. Tripteris sinuatum and Tetragoma froticosa were investigated on heavily grazed communal and lightly grazed commercial rangeland in the succulent karoo. Namaqualand. Seed production in both these species was substantially reduced on the ...

Shrub expansion may reduce summer permafrost thaw in Siberian tundra

NARCIS (Netherlands)

Blok, D.; Heijmans, M.M.P.D.; Schaepman-Strub, G.; Kononov, A.V.; Maximov, T.C.; Berendse, F.

2010-01-01

Climate change is expected to cause extensive vegetation changes in the Arctic: deciduous shrubs are already expanding, in response to climate warming. The results from transect studies suggest that increasing shrub cover will impact significantly on the surface energy balance. However, little is

Shrub Abundance Mapping in Arctic Tundra with Misr

Science.gov (United States)

Duchesne, R.; Chopping, M. J.; Wang, Z.; Schaaf, C.; Tape, K. D.

2013-12-01

Over the last 60 years an increase in shrub abundance has been observed in the Arctic tundra in connection with a rapid surface warming trend. Rapid shrub expansion may have consequences in terms of ecosystem structure and function, albedo, and feedbacks to climate; however, its rate is not yet known. The goal of this research effort is thus to map large scale changes in Arctic tundra vegetation by exploiting the structural signal in moderate resolution satellite remote sensing images from NASA's Multiangle Imaging SpectroRadiometer (MISR), mapped onto a 250m Albers Conic Equal Area grid. We present here large area shrub mapping supported by reference data collated using extensive field inventory data and high resolution panchromatic imagery. MISR Level 1B2 Terrain radiance scenes from the Terra satellite from 15 June-31 July, 2000 - 2010 were converted to surface bidirectional reflectance factors (BRF) using MISR Toolkit routines and the MISR 1 km LAND product BRFs. The red band data in all available cameras were used to invert the RossThick-LiSparse-Reciprocal BRDF model to retrieve kernel weights, model-fitting RMSE, and Weights of Determination. The reference database was constructed using aerial survey, three field campaigns (field inventory for shrub count, cover, mean radius and height), and high resolution imagery. Tall shrub number, mean crown radius, cover, and mean height estimates were obtained from QuickBird and GeoEye panchromatic image chips using the CANAPI algorithm, and calibrated using field-based estimates, thus extending the database to over eight hundred locations. Tall shrub fractional cover maps for the North Slope of Alaska were constructed using the bootstrap forest machine learning algorithm that exploits the surface information provided by MISR. The reference database was divided into two datasets for training and validation. The model derived used a set of 19 independent variables(the three kernel weights, ratios and interaction terms

GUI development for GRASS GIS

Directory of Open Access Journals (Sweden)

Martin Landa

2007-12-01

Full Text Available This article discusses GUI development for GRASS GIS. Sophisticated native GUI for GRASS is one of the key points (besides the new 2D/3D raster library, vector architecture improvements, etc. for the future development of GRASS. In 2006 the GRASS development team decided to start working on the new generation of GUI instead of improving the current GUI based on Tcl/Tk.

Mechanical mastication of Utah juniper encroaching sagebrush steppe increases inorganic soil N

Science.gov (United States)

Juniper (Juniperus spp.) has encroached millions of hectares of sagebrush (Artemisia spp.) steppe. Juniper mechanical mastication increases cover of understory species, but could increase resource availability and subsequently invasive plant species. We quantified the effects of juniper mastication ...

Leaf green-up in a semi-arid African savanna - separating tree and grass responses to environmental cues

CSIR Research Space (South Africa)

Archibald, S

2007-01-01

Full Text Available -arid African savanna - 583 Journal of Vegetation Science 18: 583-594, 2007 © IAVS; Opulus Press Uppsala. Leaf green-up in a semi-arid African savanna – separating tree and grass responses to environmental cues Archibald, S.1* & Scholes, R.J.1,2 1Natural... to identify tree and grass green-up dates in a semi-arid savanna system, and are there predictable environmental cues for green-up for each life form? Location: Acacia nigrescens/Combretum apiculatum savanna, Kruger National Park, South Africa (25° S, 31...

A Proposal on the Restoration of Nostoc flagelliforme for Sustainable Improvement in the Ecology of Arid Steppes in China

Directory of Open Access Journals (Sweden)

Xiang Gao

2016-06-01

Full Text Available Nostoc flagelliforme, a filamentous nitrogen-fixing cyanobacterium, is widely distributed in arid steppes of the west and northwestern parts of China. However, as a food delicacy this species has been overexploited from 1970 to 2000. Moreover, overgrazing, land reclamation and the removal of medicinal herbs have caused severely reduced vegetation coverage there. In this communication, a badly damaged but slowly rehabilitating N. flagelliforme-inhibiting steppe is described, and the rehabilitation of desertified steppes by the renewed growth of N. flagelliforme is proposed. The restoration of this dominant nitrogen supplier would be an ecologically sustainable solution for supplementing current measures already taken in the desertified regions. In addition, a goal of 50%–60% vegetation coverage is proposed by the N. flagelliforme restoration.

Phytomining Perspectives in Rehabilitation of Mining and Industrial Areas of South Ural

Science.gov (United States)

Timofeeva, S. S.; Ulrikh, D. V.; Timofeev, S. S.

2017-05-01

The ability of midland hawthorn (Crataegus laevigata (Poir)), common barberry (Berberis vulgaris), red elder (Sambucus racemosa), cinnamon rose (Rosa cinnamomea L.), couch grass (Elytrigia repens), crested wheat grass (Agropyron cristatum), meadow fescue (Festuca pratensis) and meadow grass (Poa pratensis) for phytoextraction of heavy metals from technogenic soil is proved in the article. The possibility of effective phytoextraction with the use of hawthorn and elder is shown. Maximum accumulation of zinc takes place in the surface mass of couch grass and meadow fescue. In regard to the conditions of South Ural, planting of elder and hawthorn with seeding of couch grass and meadow fescue is recommended for phytomining purposes.

The effect of ensiling and haymaking on the concentrations of steroidal saponin in two Brachiaria grass species

Science.gov (United States)

Brachiaria (signalgrass) is now the most widely used tropical grass genus in Central and South America. However, Brachiaria spp. can cause hepatogenous photosensitization in livestock. Steroidal saponins, specifically protodioscin, present in Brachiaria spp. may be responsible for liver injury and s...

Evaluation of shrub and tree species used for revegetating copper mine wastes in the south-western United States. [Dodonea viscosa (L. ) Jacq. , Baccharis sarothroides Gray, Cerdicium microphyllum Torr. , and Nicotiana glauca Grah

Energy Technology Data Exchange (ETDEWEB)

Norem, M A; Day, A D; Ludeke, K L

1982-12-01

The revegetation work begun in 1970 at Cyprus Pima Mine, an open pit copper mine south-west of Tucson, Arizona, was evaluated to determine the effects of slope aspect and mining waste material on plant survival and growth. Only one shrub, Dodonea viscosa (L.) Jacq. (hopbush), survived on the east slope. Baccharis sarothroides Gray (desert broom) was prolific on the north aspect. Cerdicium microphyllum Torr. (palo verde) survived best on the east slope and Nicotiana glauca Grah. (desert tobacco) survived only on the north slope. The survival of the other tree species was not affected by slope aspect. Slope exposure did not affect tree size, except for Eucalyptus microtheca Muell. (tiny capsule eucalyptus) which grew larger on the north slope. E. rostrata Schlechtend (red gum eucalyptus) grew taller in overburden than in tailing on the east slope. Differences in soil material within each slope exposure did not significantly affect growth of the other tree species. In semi-arid regions, such as south-western Arizona, even slight differences in available moisture may determine the survival of a plant species in the area. (Refs. 11).

Management Approaches to Accomplish Contemporary Livestock Production-Conservation Objectives in Shortgrass Steppe

Science.gov (United States)

Traditional rangeland management in the shortgrass steppe has emphasized livestock production with moderate stocking rates, but alternative approaches will be needed to meet production objectives under increasing demands for conservation-oriented management. We investigated the utility of very inten...

Methods for measuring arctic and alpine shrub growth: A review

NARCIS (Netherlands)

Myers-Smith, I.H.; Hallinger, M.; Blok, D.; Sass-Klaassen, U.G.W.; Rayback, S.A.

2015-01-01

Shrubs have increased in abundance and dominance in arctic and alpine regions in recent decades. This often dramatic change, likely due to climate warming, has the potential to alter both the structure and function of tundra ecosystems. The analysis of shrub growth is improving our understanding of

Baseline data on wild flora of crop field boundaries in the agro-ecosystem of pothwar plateau, pakistan

International Nuclear Information System (INIS)

Sarwar, M.; Hussain, I.; Anwar, M.; Ashraf, N.; Mirza, S.N.

2017-01-01

Wild flora along crop field boundaries in farmlands not only increases habitat heterogeneity but also serves multiple beneficial functions. We collected baseline data on wild flora bordering the crop fields of Pothwar plateau. Overall we selected four study sites including two sites of wheat-maize/millet and two of wheat-groundnut cropping system. We recorded 51 species of plants including 12 species of trees, 14 species of shrubs and 25 species of grasses/herbs. Two tree species namely Acacia modesta and Zizyphus mauritiana and two shrub species namely Calotropis procera and Ziziphus nummularia were common indicating their widespread presence in the area. Among herbs/grasses Abutilon indicum, Amaranthus spp., Cyperus rotundus and Erogrostis poroles were common at sites with wheat-maize/millet cropping pattern while Chenopodium album, Datura stramonium and Tribulus terrestris were common at sites with wheat-groundnut cropping system. The tree and shrub densities did not differ significantly among the study sites. Wheat-groundnut cropping system had higher populations/diversity/species of shrubs as compared to wheat-maize/millet cropping system. Density of grasses/herbs significantly differed across the study sites but there was no association of herb/grass density with cropping practice. (author)

[Quality level assessment of lowly efficient Tamarix chinensis secondary shrubs in Laizhou Bay of Yellow River Delta].

Science.gov (United States)

Xia, Jiang-Bao; Liu, Yu-Ting; Zhu, Jin-Fang; Xu, Jing-Wei; Lu, Zhao-Hua; Liu, Jing-Tao; Liu, Qing

2013-06-01

Taking the Tamarix chinensis secondary shrubs in Laizhou Bay of Yellow River Delta as test objects, and by using synthetic factor method, this paper studied the main factors causing the lowly efficiency of T. chinensis secondary shrubs as well as the main parameters for the classification of lowly efficient T. chinensis secondary shrubs. A total of 24 indices including shrubs growth and soil physical and chemical properties were selected to determine the main affecting factors and parameters in evaluating and classifying the lowly efficient shrubs. There were no obvious correlations between the indices reflecting the shrubs growth and soil quality, and thus, only using shrub growth index to reflect the lowly efficiency level of T. chinensis was not enough, and it would be necessary to combine with soil quality factors to make a comprehensive evaluation. The principal factors reflecting the quality level of lowly efficient T. chinensis shrubs included soil salt content and moisture content, stand age, single tree's aboveground stem, leaf biomass, and basal diameter, followed by soil density, porosity, and soil nutrient status. The lowly efficient T. chinensis shrubs in the Bay could be classified into five types, namely, shrub with growth potential, slightly low quality shrub, moderately lowly efficient shrub, moderately low quality and lowly efficient shrub, and seriously low quality and lowly efficient shrub. The main features, low efficiency causes, and management measures of these shrubs were discussed based on the mean cluster value.

Genome sequence analysis of the model grass Brachypodium distachyon: insights into grass genome evolution

Energy Technology Data Exchange (ETDEWEB)

Schulman, Al

2009-08-09

Three subfamilies of grasses, the Erhardtoideae (rice), the Panicoideae (maize, sorghum, sugar cane and millet), and the Pooideae (wheat, barley and cool season forage grasses) provide the basis of human nutrition and are poised to become major sources of renewable energy. Here we describe the complete genome sequence of the wild grass Brachypodium distachyon (Brachypodium), the first member of the Pooideae subfamily to be completely sequenced. Comparison of the Brachypodium, rice and sorghum genomes reveals a precise sequence- based history of genome evolution across a broad diversity of the grass family and identifies nested insertions of whole chromosomes into centromeric regions as a predominant mechanism driving chromosome evolution in the grasses. The relatively compact genome of Brachypodium is maintained by a balance of retroelement replication and loss. The complete genome sequence of Brachypodium, coupled to its exceptional promise as a model system for grass research, will support the development of new energy and food crops

Transfer of 238U, 230Th, 226Ra, and 210Pb from soils to tree and shrub species in a Mediterranean area

International Nuclear Information System (INIS)

Blanco Rodriguez, P.; Vera Tome, F.; Lozano, J.C.; Perez Fernandez, M.A.

2010-01-01

The soil-to-plant transfer factors of natural uranium isotopes ( 238 U and 234 U), 230 Th, 226 Ra, and 210 Pb were studied in a disused uranium mine located in the Extremadura region in the south-west of Spain. The plant samples included trees (Quercus ilex, Quercus suber, and Eucalyptus cameldulensis) and one shrub (Cytisus multiflorus). All of them are characteristic of Mediterranean environments. The activity concentrations in leaves and fruit were determined for the tree species at different stages of growth. For the shrub, the total above-ground fraction was considered in three seasons. For old leaves and fruit, the highest activity concentrations were found in Eucalyptus cameldulensis for all the radionuclides studied, except in the case of 230 Th that presented similar activity concentrations in all of the tree species studied. In every case, the transfer to fruit was less than the transfer to leaves. In the shrub, the results depended on the season of sampling, with the highest value obtained in spring and the lowest in autumn. Important correlations were obtained for 238 U and 226 Ra between the activity ratio in soils with that in leaves or fruit.

Water storage capacity, stemflow and water funneling in Mediterranean shrubs

Science.gov (United States)

Garcia-Estringana, P.; Alonso-Blázquez, N.; Alegre, J.

2010-08-01

SummaryTo predict water losses and other hydrological and ecological features of a given vegetation, its water storage capacity and stemflow need to be accurately determined. Vast areas of the Mediterranean region are occupied by shrublands yet there is scarce data available on their rainwater interception capacity. In this study, simulated rainfall tests were conducted in controlled conditions on nine Mediterranean shrubs of varying anatomic and morphological features to determine water storage capacity, stemflow and the funneling ratio. After assessing correlations between these hydrological variables and the biometric characteristics of the shrubs, we compared two methods of determining storage capacity: rainfall simulation and immersion. Mean water storage capacity was 1.02 mm (0.35-3.24 mm), stemflow was 16% (3.8-26.4%) and the funneling ratio was 104 (30-260). Per unit biomass, mean storage capacity was 0.66 ml g -1 and ranged from 0.23 ml g -1 for Cistus ladanifer to 2.26 ml g -1 for Lavandula latifolia. Despite their small size, shrubs may generate high water losses to the atmosphere when they form dense communities and this can have a significant impact in regions where water is scarce. When considered the whole shrubs in absolute terms (ml per plant), water storage capacity and stemflow were correlated to biomass and the dendrometric characteristics of the shrubs, yet in relative terms (expressed per surface area unit or as %), anatomic features such as pubescence, branch rigidity or leaf insertion angle emerged as determining factors. The use of a simple procedure to assess storage capacity was inefficient. The immersion method underestimated storage capacity to a different extent for each species. Some shrubs returned high stemflow values typical of their adaptation to the semiarid climate. In contrast, other shrubs seem to have structures that promote stemflow yet have developed other drought-adaptation mechanisms. In this report, we discuss the

Lethal Encephalitozoon cuniculi genotype III infection in Steppe lemmings (Lagurus lagurus)

Czech Academy of Sciences Publication Activity Database

Hofmannová, L.; Sak, Bohumil; Jekl, V.; Mináriková, A.; Škorič, M.; Kváč, Martin

2014-01-01

Roč. 205, 1-2 (2014), s. 357-360 ISSN 0304-4017 R&D Projects: GA ČR(CZ) GAP505/11/1163 Institutional support: RVO:60077344 Keywords : Encephalitozoon cuniculi genotype III * Steppe lemmings * Lethal infection * PCR * Histology Subject RIV: EG - Zoology Impact factor: 2.460, year: 2014

Responsiveness to timothy grass pollen in individuals without known natural exposure in an allergen challenge chamber.

Science.gov (United States)

Ramirez, Daniel A; Andrews, Charles P; Rather, Cynthia G; Jacobs, Robert L

2015-03-01

The responsiveness to a nonendemic grass species is unknown and cannot be research without an allergen challenge chamber. To determine the clinical responsiveness to timothy grass pollen (TGP) in participants without known natural exposure in an allergen challenge chamber (ACC). Of the 26 screened participants, 22 met screening criteria and completed the 2 chamber exposures. The study consisted of an initial screening visit that included a blood draw for serum specific IgE (ssIGE) to Bermuda grass pollen and TGP followed by a 4½-day run-in phase and two 3-hour ACC exposure visits. This study was performed early in the first week of December 2013, when no seasonal pollens were detected in San Antonio, Texas. Symptom scores were recorded at baseline and every 30 minutes. Of the 26 screened participants, 22 met the screening criteria and completed the 2 chamber exposures. Thirteen participants had always lived in South Texas without natural exposure, and 9 had previously lived in areas with TGP exposure. All participants tested positive to TGP and Bermuda grass pollen. Twelve and 13 of 22 had positive ssIgE test results to Timothy and Bermuda allergens, respectively, with 11 having positive results for both allergens. There were strong correlations among skin prick test size, a positive ssIgE test result, and high symptoms from TGP exposure. There was little difference in symptoms between those who had lived their entire lives in South Texas and those who had lived elsewhere. In Texas, where exposure to TGP is minimal, strongly positive SPT and ssIgE test results were predictors of high symptoms to TGP exposure. Never exposed participants in South Texas reacted to TGP similar to those who had previous natural exposure, suggesting that in vivo cross-reactivity may be higher than predicted by prior in vitro data and may allow the use in clinical trials of allergens not endemic to the locale of an ACC. Copyright © 2015 American College of Allergy, Asthma & Immunology

Effects of Spring Drought on Carbon Sequestration, Evapotranspiration and Water Use Efficiency in the Songnen Meadow Steppe in Northeast China.

Science.gov (United States)

Gang Dong; Jixun Guo; Jiquan Chen; Ge Sun; Song Gao; et al

2011-01-01

Global climate change projections suggest an increasing frequency of droughts and extreme rain events in the steppes of the Eurasian region. Using the eddy covariance method, we measured carbon and water balances of a meadow steppe ecosystem in Northeast China during 2 years which had contrasting precipitation patterns in spring seasons in 2007 and 2008. The meadow...

238U, and its decay products, in grasses from an abandoned uranium mine

Science.gov (United States)

Childs, Edgar; Maskall, John; Millward, Geoffrey

2016-04-01

Bioaccumulation of radioactive contaminants by plants is of concern particularly where the sward is an essential part of the diet of ruminants. The abandoned South Terras uranium mine, south west England, had primary deposits of uraninite (UO2) and pitchblende (U3O8), which contained up to 30% uranium. When the mine was active uranium and radium were extracted but following closure it was abandoned without remediation. Waste rock and gangue, consisting of inefficiently processed minerals, were spread around the site, including a field where ruminants are grazed. Here we report the activity concentrations of 238U, 235U 214,210Pb, and the concentrations of selected metals in the soils, roots and leaves of grasses taken from the contaminated field. Soil samples were collected at the surface, and at 30 cm depth, using an auger along a 10-point transect in the field from the foot of a waste heap. Whole, individual grass plants were removed with a spade, ensuring that their roots were intact. The soils and roots and grass leaves were freeze-dried. Activity concentrations of the radionuclides were determined by gamma spectroscopy, following 30 days incubation for development of secular equilibrium. Dried soils, roots and grasses were also digested in aqua regia and the concentrations of elements determined by ICP techniques. Maximum activity concentrations of 238U, 235U, 214Pb and 210Pb surface soils were 63,300, 4,510, 23,300 and 49,400 Bq kg-1, respectively. The mean 238U:235U ratio was 11.8 ± 1.8, an order of magnitude lower than the natural value of 138, indicating disequilibrium within the decay chain due to mineral processing. Radionuclides in the roots had 5 times lower concentration and only grass leaves in the vicinity of the waste heap had measureable values. The mean soil to root transfer factor for 238U was 36%, the mean root to leaf was 3% and overall only 0.7% of 238U was transferred from the soil to the leaves. The roots contained 0.8% iron, possibly as

Assessing habitat type in KZN estuaries using VHR remote sensing imagery

CSIR Research Space (South Africa)

Lück-Vogel, Melanie

2014-10-01

Full Text Available : - Various degrees of flooding between images in saltmarsh, groundwater fed, reeds, juncus, mangroves - Rapid vegetation succession from grass/shrubs to swamp forest - Single flood events eradicated entire submerged vegetation patches - Salinity changes... in saltmarsh, groundwater fed, reeds, juncus, mangroves - Rapid vegetation succession from grass/shrubs to swamp forest - Single flood events eradicated entire submerged vegetation patches - Salinity changes (?) prompted shift from submerged to reeds...

Low-volume and slow-burning vegetation for planting on clearings in California chaparral

Science.gov (United States)

Eamor C. Nord; Lisle R. Green

1977-01-01

Vegetation that is low-growing and either low in volume, slow burning, or both, is needed for reduction of fire hazard on fuelbreaks and other brush cleared areas in California. Of over 50 shrub species and many grass species that were test planted, about 20 shrubs and an equal number of grasses were chosen for plot and field trials. Creeping sage, a few saltbushes,...

Nature: a colour comparison between Northern South Africa and Northern Australia

CSIR Research Space (South Africa)

Baumbach, J

2009-10-01

Full Text Available During 1983 DSTO in Australia measured the reflectances of grass, trees and soil in northern Australia, using a custom-build spectroradiometer. During 2002 CSIR in South Africa performed similar measurements in northern South Africa, using a...

Dynamics of Understory Shrub Biomass in Six Young Plantations of Southern Subtropical China

Directory of Open Access Journals (Sweden)

Yuanqi Chen

2017-11-01

Full Text Available Understory shrubs are an important component of forest ecosystems and drive ecosystem processes, such as ecosystem carbon cycling. However, shrub biomass carbon stocks have rarely been reported, which limits our understanding of ecosystem C stock and cycling. In this study, we evaluated carbon accumulation of shrub species using allometric equations based on height and basal diameter in six subtropical plantations at the age of 1, 3, 4 and 6 years. The results showed that plantation type did not significantly affect the total biomass of shrubs, but it significantly affected the biomass of Rhodomyrtus tomentosa, Ilex asprella, Clerodendrum fortunatum and Baeckea frutescens. The biomass of dominant shrub species R. tomentosa, I. asprella, Gardenia jasminoides and Melastoma candidum increased with stand age, while the biomass of C. fortunatum and B. frutescens decreased. The inconsistent biomass-time patterns of different shrub species may be the primary reason for the altered total shrub biomass in each plantation. Consequently, we proposed that R. tomentosa, I. asprella, G. jasminoides and M. candidum could be preferable for understory carbon accumulation and should be maintained or planted because of their important functions in carbon accumulation and high economic values in the young plantations of southern subtropical China.

[Spatial distribution of aboveground biomass of shrubs in Tianlaochi catchment of the Qilian Mountains].

Science.gov (United States)

Liang, Bei; Di, Li; Zhao, Chuan-Yan; Peng, Shou-Zhang; Peng, Huan-Hua; Wang, Chao

2014-02-01

This study estimated the spatial distribution of the aboveground biomass of shrubs in the Tianlaochi catchment of Qilian Mountains based on the field survey and remote sensing data. A relationship model of the aboveground biomass and its feasibly measured factors (i. e. , canopy perimeter and plant height) was built. The land use was classified by object-oriented technique with the high resolution image (GeoEye-1) of the study area, and the distribution of shrub coverage was extracted. Then the total aboveground biomass of shrubs in the study area was estimated by the relationship model with the distribution of shrub coverage. The results showed that the aboveground biomass of shrubs in the study area was 1.8 x 10(3) t and the aboveground biomass per unit area was 1598.45 kg x m(-2). The distribution of shrubs mainly was at altitudes of 3000-3700 m, and the aboveground biomass of shrubs on the sunny slope (1.15 x 10(3) t) was higher than that on the shady slope (0.65 x 10(3) t).

Disaggregating tree and grass phenology in tropical savannas

Science.gov (United States)

Zhou, Qiang

Savannas are mixed tree-grass systems and as one of the world's largest biomes represent an important component of the Earth system affecting water and energy balances, carbon sequestration and biodiversity as well as supporting large human populations. Savanna vegetation structure and its distribution, however, may change because of major anthropogenic disturbances from climate change, wildfire, agriculture, and livestock production. The overstory and understory may have different water use strategies, different nutrient requirements and have different responses to fire and climate variation. The accurate measurement of the spatial distribution and structure of the overstory and understory are essential for understanding the savanna ecosystem. This project developed a workflow for separating the dynamics of the overstory and understory fractional cover in savannas at the continental scale (Australia, South America, and Africa). Previous studies have successfully separated the phenology of Australian savanna vegetation into persistent and seasonal greenness using time series decomposition, and into fractions of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV) and bare soil (BS) using linear unmixing. This study combined these methods to separate the understory and overstory signal in both the green and senescent phenological stages using remotely sensed imagery from the MODIS (MODerate resolution Imaging Spectroradiometer) sensor. The methods and parameters were adjusted based on the vegetation variation. The workflow was first tested at the Australian site. Here the PV estimates for overstory and understory showed best performance, however NPV estimates exhibited spatial variation in validation relationships. At the South American site (Cerrado), an additional method based on frequency unmixing was developed to separate green vegetation components with similar phenology. When the decomposition and frequency methods were compared, the frequency

Effects of Mediterranean shrub species on rainfall interception

International Nuclear Information System (INIS)

Garcia-Estringana, P.; Alonso-Blazquez, N.; Marques, M. J.; Bienes, R.; Alegre, J.

2009-01-01

Rainfall is intercepted by vegetation. Water intercepted could be evaporated, or it could drip from the leaves and stems to the soil or it could run down the stems to the base of the plant. In the Mediterranean, where water is a scant resource, interception loss could have an influence on hydrology. Water storage capacity depends on vegetation type. In the Mediterranean, there are many types of shrubs, and many of them are able to intercept large volumes of water depending on the shrub type. many lands of the Mediterranean basin of Europea Union have been abandoned in the last decades and consequently vegetation type changes too. This modifies hydrologic processes, changing the volume and the way in which the rainfall reaches the soil. The aim of this study was to characterize water storage capacity in 9 Mediterranean shrub species, working with the whole plant and comparing results obtained by two methods, rainfall simulation and submersion method in laboratory conditions. (Author) 12 refs.

Satellite tracking of a young Steppe Eagle from the United Arab ...

African Journals Online (AJOL)

Following recovery and successful rehabilitation, a young Steppe Eagle Aquila nipalensis was tagged with a 45 g GPS satellite transmitter to track its migration and identify potential wintering and summering areas of the species passing through the United Arab Emirates (UAE). The study is part of a larger study on ...

Determining Optimal New Generation Satellite Derived Metrics for Accurate C3 and C4 Grass Species Aboveground Biomass Estimation in South Africa

Directory of Open Access Journals (Sweden)

Cletah Shoko

2018-04-01

Full Text Available While satellite data has proved to be a powerful tool in estimating C3 and C4 grass species Aboveground Biomass (AGB, finding an appropriate sensor that can accurately characterize the inherent variations remains a challenge. This limitation has hampered the remote sensing community from continuously and precisely monitoring their productivity. This study assessed the potential of a Sentinel 2 MultiSpectral Instrument, Landsat 8 Operational Land Imager, and WorldView-2 sensors, with improved earth imaging characteristics, in estimating C3 and C4 grasses AGB in the Cathedral Peak, South Africa. Overall, all sensors have shown considerable potential in estimating species AGB; with the use of different combinations of the derived spectral bands and vegetation indices producing better accuracies. However, WorldView-2 derived variables yielded better predictive accuracies (R2 ranging between 0.71 and 0.83; RMSEs between 6.92% and 9.84%, followed by Sentinel 2, with R2 between 0.60 and 0.79; and an RMSE 7.66% and 14.66%. Comparatively, Landsat 8 yielded weaker estimates, with R2 ranging between 0.52 and 0.71 and high RMSEs ranging between 9.07% and 19.88%. In addition, spectral bands located within the red edge (e.g., centered at 0.705 and 0.745 µm for Sentinel 2, SWIR, and NIR, as well as the derived indices, were found to be very important in predicting C3 and C4 AGB from the three sensors. The competence of these bands, especially of the free-available Landsat 8 and Sentinel 2 dataset, was also confirmed from the fusion of the datasets. Most importantly, the three sensors managed to capture and show the spatial variations in AGB for the target C3 and C4 grassland area. This work therefore provides a new horizon and a fundamental step towards C3 and C4 grass productivity monitoring for carbon accounting, forage mapping, and modelling the influence of environmental changes on their productivity.

Permafrost collapse after shrub removal shifts tundra ecosystem to a methane source

DEFF Research Database (Denmark)

Nauta, Ake L.; Heijmans, Monique P.D.; Blok, Daan

2015-01-01

, including expansion of woody vegetation5,6, in response to changing climate conditions. How such vegetation changes contribute to stabilization or destabilization of the permafrost is unknown. Here we present six years of field observations in a shrub removal experiment at a Siberian tundra site. Removing...... the shrub part of the vegetation initiated thawing of ice-rich permafrost, resulting in collapse of the originally elevated shrub patches into waterlogged depressions within five years. This thaw pond development shifted the plots from a methane sink into a methane source. The results of our field......-emitting wet depressions could become more abundant in the lowland tundra landscape, at the cost of permafrost-stabilizing low shrub vegetation....

Shift in soil microbial communities with shrub encroachment in Inner Mongolia grasslands, China

Science.gov (United States)

Shen, H.; Li, H.; Zhang, J.; Hu, H.; Chen, L.; Zhu, Y.; Fang, J.

2017-12-01

The ongoing expansion of shrub encroachment into grasslands represents a unique form of land cover change. How this process affects soil microbial communities is poorly understood. In this study, we aim to assess the effects of shrub encroachment on soil microbial biomass, abundance and composition by comparing data between shrub patches and neighboring herb patches in shrub-encroached grasslands (SEGs) in Inner Mongolia, China. Fourteen SEG sites from two ecosystem types (typical and desert grasslands) were investigated. The phospholipid fatty acid (PLFA) method was used to analyze the composition and biomass of the soil microbial community. Our results showed that the top-soil microbial biomass and abundances of gram-negative bacteria, arbuscular mycorrhizal fungi, and actinomycetes were significantly higher in shrub patches than in herb patches in both typical and desert grasslands (P fungi to bacteria ratio was significantly higher in shrub patches than in herb patches in desert grassland (P soil microbial communities, which makes the microbial communities toward a fresh organic carbon-based structure. This study highlights the importance of edaphic and climate factors in microbial community shifts in SEGs.

Caractérisation des miels produits dans la région steppique de Djelfa en Algérie

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Mekious, S.

2015-01-01

Full Text Available Characterization of honeys produced in the region of Djelfa steppe land in Algeria. Description of the subject. This paper deals with the quality of honeys produced in the steppe areas of Algeria and discusses the possibility of their valorization. Objectives. The objective was to characterize and compare the physical and chemical quality of honeys and to determine their pollen composition according to their geographical origin in three areas of the Djelfa semi-arid region of Algeria. Method. Thirty-eight samples of honey produced in 11 localities in the north, centre and south of the Djelfa semi-arid steppe region were harvested in July for two consecutive years. Pollen analyses were performed and the following properties of the honey samples were determined: water content, pH level, electrical conductivity, color, hydroxymethylfurfural content, saccharase index, diastase index and carbohydrate profile. Results. The results of the pollen analyses identified 34 taxa of pollen. The most abundant pollens were from the Ziziphus lotus, which were present in 97.12% of the samples. The pollens from this shrub were dominant in 27 of the honey samples tested, with a pollen percentage of greater than 45%. Over 55% of the pollen frequencies found came from plants belonging to Asteracae, Brassicaceae, Cistaceae and more particularly to Euphorbia bupleuroides, Peganum harmala, Thapsia garganica, Echium sp. and Retama retam. Conclusions. The physicochemical parameters of the honey samples studied comply with European and international quality standards, which opens up perspectives for their valorization.

Are invasive aliens a real threat to biodiversity in South Africa?

CSIR Research Space (South Africa)

Van Wilgen, B

2011-01-01

Full Text Available South Africa has abundant biodiversity, but also many invasive alien species, especially plants and fish, that can transform ecosystems. Invading alien trees and shrubs impact on fynbos and threaten up to a quarter of the nation's plant species...

Prescribed burning in mid and late successional juniper woodlands

Science.gov (United States)

Western juniper woodlands of the western United States have expanded rapidly since settlement in the late 1800’s. To recover shrub steppe and other plant communities requires that invasive junipers be controlled. We have evaluated recovery of several plant associations after combinations of junipe...

Promoting Action on Research Implementation in Health Services framework applied to TeamSTEPPS implementation in small rural hospitals.

Science.gov (United States)

Ward, Marcia M; Baloh, Jure; Zhu, Xi; Stewart, Greg L

A particularly useful model for examining implementation of quality improvement interventions in health care settings is the PARIHS (Promoting Action on Research Implementation in Health Services) framework developed by Kitson and colleagues. The PARIHS framework proposes three elements (evidence, context, and facilitation) that are related to successful implementation. An evidence-based program focused on quality enhancement in health care, termed TeamSTEPPS (Team Strategies and Tools to Enhance Performance and Patient Safety), has been widely promoted by the Agency for Healthcare Research and Quality, but research is needed to better understand its implementation. We apply the PARIHS framework in studying TeamSTEPPS implementation to identify elements that are most closely related to successful implementation. Quarterly interviews were conducted over a 9-month period in 13 small rural hospitals that implemented TeamSTEPPS. Interview quotes that were related to each of the PARIHS elements were identified using directed content analysis. Transcripts were also scored quantitatively, and bivariate regression analysis was employed to explore relationships between PARIHS elements and successful implementation related to planning activities. The current findings provide support for the PARIHS framework and identified two of the three PARIHS elements (context and facilitation) as important contributors to successful implementation. This study applies the PARIHS framework to TeamSTEPPS, a widely used quality initiative focused on improving health care quality and patient safety. By focusing on small rural hospitals that undertook this quality improvement activity of their own accord, our findings represent effectiveness research in an understudied segment of the health care delivery system. By identifying context and facilitation as the most important contributors to successful implementation, these analyses provide a focus for efficient and effective sustainment of TeamSTEPPS

Range Expansion of Moose in Arctic Alaska Linked to Warming and Increased Shrub Habitat.

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Ken D Tape

Full Text Available Twentieth century warming has increased vegetation productivity and shrub cover across northern tundra and treeline regions, but effects on terrestrial wildlife have not been demonstrated on a comparable scale. During this period, Alaskan moose (Alces alces gigas extended their range from the boreal forest into tundra riparian shrub habitat; similar extensions have been observed in Canada (A. a. andersoni and Eurasia (A. a. alces. Northern moose distribution is thought to be limited by forage availability above the snow in late winter, so the observed increase in shrub habitat could be causing the northward moose establishment, but a previous hypothesis suggested that hunting cessation triggered moose establishment. Here, we use recent changes in shrub cover and empirical relationships between shrub height and growing season temperature to estimate available moose habitat in Arctic Alaska c. 1860. We estimate that riparian shrubs were approximately 1.1 m tall c. 1860, greatly reducing the available forage above the snowpack, compared to 2 m tall in 2009. We believe that increases in riparian shrub habitat after 1860 allowed moose to colonize tundra regions of Alaska hundreds of kilometers north and west of previous distribution limits. The northern shift in the distribution of moose, like that of snowshoe hares, has been in response to the spread of their shrub habitat in the Arctic, but at the same time, herbivores have likely had pronounced impacts on the structure and function of these shrub communities. These northward range shifts are a bellwether for other boreal species and their associated predators.

Range expansion of moose in arctic Alaska linked to warming and increased shrub habitat

Science.gov (United States)

Tape, Ken D.; Gustine, David D.; Reuss, Roger W.; Adams, Layne G.; Clark, Jason A.

2016-01-01

Twentieth century warming has increased vegetation productivity and shrub cover across northern tundra and treeline regions, but effects on terrestrial wildlife have not been demonstrated on a comparable scale. During this period, Alaskan moose (Alces alces gigas) extended their range from the boreal forest into tundra riparian shrub habitat; similar extensions have been observed in Canada (A. a. andersoni) and Eurasia (A. a. alces). Northern moose distribution is thought to be limited by forage availability above the snow in late winter, so the observed increase in shrub habitat could be causing the northward moose establishment, but a previous hypothesis suggested that hunting cessation triggered moose establishment. Here, we use recent changes in shrub cover and empirical relationships between shrub height and growing season temperature to estimate available moose habitat in Arctic Alaska c. 1860. We estimate that riparian shrubs were approximately 1.1 m tall c. 1860, greatly reducing the available forage above the snowpack, compared to 2 m tall in 2009. We believe that increases in riparian shrub habitat after 1860 allowed moose to colonize tundra regions of Alaska hundreds of kilometers north and west of previous distribution limits. The northern shift in the distribution of moose, like that of snowshoe hares, has been in response to the spread of their shrub habitat in the Arctic, but at the same time, herbivores have likely had pronounced impacts on the structure and function of these shrub communities. These northward range shifts are a bellwether for other boreal species and their associated predators.

Steppe development on the Northern Tibetan Plateau inferred from Paleogene ephedroid pollen

NARCIS (Netherlands)

Han, Fang; Rydin, Catarina; Bolinder, Kristina; Dupont-Nivet, Guillaume; Abels, Hemmo A.; Koutsodendris, Andreas; Zhang, Kexin; Hoorn, Carina

2016-01-01

Steppe vegetation represents a key marker of past Asian aridification and is associated with monsoonal intensification. Little is, however, known about the origin of this pre-Oligocene vegetation, its specific composition and how it changed over time and responded to climatic variations. Here, we

Siliceous Shrubs in Yellowstone's Hot Springs: Implications for Exobiological Investigations

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Guidry, S. A.; Chafetz, H. S.

2003-01-01

Potential relict hot springs have been identified on Mars and, using the Earth as an analog, Martian hot springs are postulated to be an optimal locality for recognizing preserved evidence of extraterrestrial life. Distinctive organic and inorganic biomarkers are necessary to recognize preserved evidence of life in terrestrial and extraterrestrial hot spring accumulations. Hot springs in Yellowstone National Park, Wyoming, U.S.A., contain a wealth of information about primitive microbial life and associated biosignatures that may be useful for future exobiological investigations. Numerous siliceous hot springs in Yellowstone contain abundant, centimeter-scale, spinose precipitates of opaline silica (opal-A). Although areally extensive in siliceous hot spring discharge channel facies, these spinose forms have largely escaped attention. These precipitates referred to as shrubs, consist of porous aggregates of spinose opaline silica that superficially resemble miniature woody plants, i.e., the term shrubs. Shrubs in carbonate precipitating systems have received considerable attention, and represent naturally occurring biotically induced precipitates. As such, shrubs have great potential as hot spring environmental indicators and, more importantly, proxies for pre-existing microbial life.

Environmental Limits of Tall Shrubs in Alaska’s Arctic National Parks

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Swanson, David K.

2015-01-01

We sampled shrub canopy volume (height times area) and environmental factors (soil wetness, soil depth of thaw, soil pH, mean July air temperature, and typical date of spring snow loss) on 471 plots across five National Park Service units in northern Alaska. Our goal was to determine the environments where tall shrubs thrive and use this information to predict the location of future shrub expansion. The study area covers over 80,000 km2 and has mostly tundra vegetation. Large canopy volumes were uncommon, with volumes over 0.5 m3/m2 present on just 8% of plots. Shrub canopy volumes were highest where mean July temperatures were above 10.5°C and on weakly acid to neutral soils (pH of 6 to 7) with deep summer thaw (>80 cm) and good drainage. On many sites, flooding helped maintain favorable soil conditions for shrub growth. Canopy volumes were highest where the typical snow loss date was near 20 May; these represent sites that are neither strongly wind-scoured in the winter nor late to melt from deep snowdrifts. Individual species varied widely in the canopy volumes they attained and their response to the environmental factors. Betula sp. shrubs were the most common and quite tolerant of soil acidity, cold July temperatures, and shallow thaw depths, but they did not form high-volume canopies under these conditions. Alnus viridis formed the largest canopies and was tolerant of soil acidity down to about pH 5, but required more summer warmth (over 12°C) than the other species. The Salix species varied widely from S. pulchra, tolerant of wet and moderately acid soils, to S. alaxensis, requiring well-drained soils with near neutral pH. Nearly half of the land area in ARCN has mean July temperatures of 10.5 to 12.5°C, where 2°C of warming would bring temperatures into the range needed for all of the potential tall shrub species to form large canopies. However, limitations in the other environmental factors would probably prevent the formation of large shrub canopies

Evidence for opal phytolith preservation in the Langebaanweg ‘E’ Quarry Varswater Formation and its potential for palaeohabitat reconstruction

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P. Haarhof

2010-01-01

Full Text Available At the end of the Miocene epoch, C4 grasslands began to expand at the expense of tree-, shrub- and forb-dominated C3 ecosystems. While C4 grasses were spreading throughout most regions of the world, C3 grasses may have been spreading along South Africa’s southwest coast. Stable isotope analyses of hypsodont fossil ungulates from ‘E’ Quarry, a well-known Late Miocene/Early Pliocene fossil locality near the town of Langebaanweg, suggest that the local environment might have included a substantial C3 grass component. Besides this indirect evidence, little is known about the evolution, nature and importance of grass in the ‘E’ Quarry biome. As a preliminary step towards addressing these questions, we initiated a trial investigation to assess whether sediments at the site are conducive to the preservation of phytoliths, an important tool in the reconstruction of palaeohabitats. Results indicate that fossil phytoliths are sufficiently well preserved to allow a comprehensive analysis of the ‘E’ Quarry phytolith assemblage.

About rehabilitation of vegetation of disturbed ecosystems of the Semipalatinsk test sites

International Nuclear Information System (INIS)

Plisak, R.P.; Plisak, S.V.

2005-01-01

areas is characterized by: 1. slight influence of zonal conditions and steppe vegetation on primary stages of restorative succession; 2. under PED of γ-irradiation of 20-200 μR/h vegetation rehabilitation begins with invasion of weed species; 3. under high levels of chronic ionizing irradiation (PED of γ-irradiation 800-5000 μR/h and higher) vegetation rehabilitation is limited by level of radiation pollution; 4. on primary stages of vegetation rehabilitation leading role belongs to annuals, biennials, perennial rhizome herbs and cespitosehemi chrysophyte; 5. besides eurytopic weed plants species of local flora (xerophyte-steppe cespitose grasses, shrubs-petrophytes, in valleys of rivers and springs-mesophytes) participate in restoration of vegetation of technogene ecotopes; 6. great importance in the process of vegetation restoration belongs to herbs, role of shrubs is insignificant; 7. radiation pollution of damaged areas provokes decrease of specie diversity. 8. For restoration of vegetation of Semipalatinsk Test Sites it is necessary to conduct out; 9. rehabilitation of its territory (remove poured polluted material, remains of debris, fragments of military and technical objects, surface layer of polluted soils); 10. technical preparation of ground of the dumps (laying out, terracing), its biological re-cultivation (restoration of soils, fixing of fine earth on slopes of the dumps) and phyto melioration; 11. phyto remediation of soils of polluted areas

Cellular-automata model of the dwarf shrubs populations and communities dynamics

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A. S. Komarov

2015-06-01

Full Text Available The probabilistic cellular-automata model of development and long-time dynamics of dwarf shrub populations and communities is developed. It is based on the concept of discrete description of the plant ontogenesis and joint model approaches in terms of probabilistic cellular automata and L-systems by Lindenmayer. Short representation of the basic model allows evaluation of the approach and software implementation. The main variables of the model are a number of partial bushes in clones or area projective cover. The model allows us to investigate the conditions of self-maintenance and sustainability population under different environmental conditions (inaccessibility of the territory for settlement, mosaic moisture conditions of soil and wealth. The model provides a forecast of the total biomass dynamics shrubs and their fractions (stems, leaves, roots, fine roots, fruits on the basis of the data obtained in the discrete description of ontogenesis and further information on the productivity of the plant fractions. The inclusion of the joint dynamics of biomass of shrubs and soil in EFIMOD models cycle of carbon and nitrogen to evaluate the role of shrubs in these circulations, especially at high impact, such as forest fires and clear cutting, allow forecasting of the dynamics of populations and ecosystem functions of shrubs (regulation of biogeochemical cycles maintaining biodiversity, participation in the creation of non-wood products with changing climatic conditions and strong damaging effects (logging, fires; and application of the models developed to investigate the stability and productivity of shrubs and their participation in the cycle of carbon and nitrogen in different climatic and edaphic conditions.

Tundra plant above-ground biomass and shrub dominance mapped across the North Slope of Alaska

Science.gov (United States)

Berner, Logan T.; Jantz, Patrick; Tape, Ken D.; Goetz, Scott J.

2018-03-01

Arctic tundra is becoming greener and shrubbier due to recent warming. This is impacting climate feedbacks and wildlife, yet the spatial distribution of plant biomass in tundra ecosystems is uncertain. In this study, we mapped plant and shrub above-ground biomass (AGB; kg m-2) and shrub dominance (%; shrub AGB/plant AGB) across the North Slope of Alaska by linking biomass harvests at 28 field sites with 30 m resolution Landsat satellite imagery. We first developed regression models (p plant AGB (r 2 = 0.79) and shrub AGB (r 2 = 0.82) based on the normalized difference vegetation index (NDVI) derived from imagery acquired by Landsat 5 and 7. We then predicted regional plant and shrub AGB by combining these regression models with a regional Landsat NDVI mosaic built from 1721 summer scenes acquired between 2007 and 2016. Our approach employed a Monte Carlo uncertainty analysis that propagated sampling and sensor calibration errors. We estimated that plant AGB averaged 0.74 (0.60, 0.88) kg m-2 (95% CI) and totaled 112 (91, 135) Tg across the region, with shrub AGB accounting for ~43% of regional plant AGB. The new maps capture landscape variation in plant AGB visible in high resolution satellite and aerial imagery, notably shrubby riparian corridors. Modeled shrub AGB was strongly correlated with field measurements of shrub canopy height at 25 sites (rs  = 0.88) and with a regional map of shrub cover (rs  = 0.76). Modeled plant AGB and shrub dominance were higher in shrub tundra than graminoid tundra and increased between areas with the coldest and warmest summer air temperatures, underscoring the fact that future warming has the potential to greatly increase plant AGB and shrub dominance in this region. These new biomass maps provide a unique source of ecological information for a region undergoing rapid environmental change.

COMPARATIVE ANALYSIS OF THE COMPOSITION OF THE TERRESTRIAL FAUNA AND FLORA OF THE TETHYS DESERT-STEPPE REGION OF PALEARARTICS, BIOGEOGRAPHIC BOUNDARIES OF THE CAUCASUS. MESSAGE 1. TERRESTRIAL FAUNA

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G. M. Abdurakhmanov

2017-01-01

Full Text Available Aim. The aim is to conduct a comparative analysis of the composition of the terrestrial fauna of the Tethys desert-steppe region of the Palearctic.Materials and methods. The work was based on the materials collected in different republics and regions of the Caucasus and the south of the European part of Russia during 50 years (from 1961 to 2016 which are kept in various domestic and foreign institutions. Catalogs on the studied model groups were also used to conduct the research. In making the dendrograms, a cluster analysis based on the Jaccard coefficient was used.Results. A detailed analysis was carried out by model groups of the animals of the Eastern and Western Thethys complexes of the desert-steppe region of the Palearctic. Comparative analysis has shown that a significant number of species and genera of the discussed territories is characterized by an exceptionally high ratio of endemic species and superspecies taxa. Indicators of endemism in model groups fluctuate depending on the population's ability to resettle. High endemism of faunas of darkling beetles, ground beetles, click beetles and land snails in the Eastern Tethys complex was noted.Conclusion. The Caucasus (in a new interpretation is characterized by a high percentage of endemism for the studied model groups. A large number of the common Tethys genera and species in all model groups attests to their fundamental role in the overall composition of the biota against the background of powerful autochthonous centers of species-formation and, most importantly, the formation and functioning of the Palaearctic desert-steppe belt as the Tethys ocean reduced. 

Phylogeny, diet, and habitat of an extinct ground sloth from Cuchillo Curá, Neuquén Province, southwest Argentina

Science.gov (United States)

Hofreiter, Michael; Betancourt, Julio L.; Sbriller, Alicia Pelliza; Markgraf, Vera; McDonald, H. Gregory

2003-01-01

Advancements in ancient DNA analyses now permit comparative molecular and morphological studies of extinct animal dung commonly preserved in caves of semiarid regions. These new techniques are showcased using a unique dung deposit preserved in a late glacial vizcacha (Lagidium sp.) midden from a limestone cave in southwestern Argentina (38.5° S). Phylogenetic analyses of the mitochondrial DNA show that the dung originated from a small ground sloth species not yet represented by skeletal material in the region, and not closely related to any of the four previously sequenced extinct and extant sloth species. Analyses of pollen and plant cuticles, as well as analyses of the chloroplast DNA, show that the Cuchillo Curá ground sloth browsed on many of the same herb, grass, and shrub genera common at the site today, and that its habitat was treeless Patagonian scrub-steppe. We envision a day when molecular analyses are used routinely to supplement morphological identifications and possibly to provide a time-lapse view of molecular diversification.

Uniform shrub growth response to June temperature across the North Slope of Alaska

Science.gov (United States)

Ackerman, Daniel E.; Griffin, Daniel; Hobbie, Sarah E.; Popham, Kelly; Jones, Erin; Finlay, Jacques C.

2018-04-01

The expansion of woody shrubs in arctic tundra alters many aspects of high-latitude ecosystems, including carbon cycling and wildlife habitat. Dendroecology, the study of annual growth increments in woody plants, has shown promise in revealing how climate and environmental conditions interact with shrub growth to affect these key ecosystem properties. However, a predictive understanding of how shrub growth response to climate varies across the heterogeneous landscape remains elusive. Here we use individual-based mixed effects modeling to analyze 19 624 annual growth ring measurements in the stems of Salix pulchra (Cham.), a rapidly expanding deciduous shrub. Stem samples were collected at six sites throughout the North Slope of Alaska. Sites spanned four landscapes that varied in time since glaciation and hence in soil properties, such as nutrient availability, that we expected would modulate shrub growth response to climate. Ring growth was remarkably coherent among sites and responded positively to mean June temperature. The strength of this climate response varied slightly among glacial landscapes, but in contrast to expectations, this variability was not systematically correlated with landscape age. Additionally, shrubs at all sites exhibited diminishing marginal growth gains in response to increasing temperatures, indicative of alternative growth limiting mechanisms in particularly warm years, such as temperature-induced moisture limitation. Our results reveal a regionally-coherent and robust shrub growth response to early season growing temperature, with local soil properties contributing only a minor influence on shrub growth. Our conclusions strengthen predictions of changes to wildlife habitat and improve the representation of tundra vegetation dynamics in earth systems models in response to future arctic warming.

Grand Coulee Dam Wildlife Mitigation Program : Pygmy Rabbit Programmatic Management Plan, Douglas County, Washington.

Energy Technology Data Exchange (ETDEWEB)

Ashley, Paul

1992-06-01

The Northwest Power Planning Council and the Bonneville Power Administration approved the pygmy rabbit project as partial mitigation for impacts caused by the construction of Grand Coulee Dam. The focus of this project is the protection and enhancement of shrub-steppe/pygmy rabbit habitat in northeastern Washington.

DYNAMICS OF ALGAE NUMBER AND BIOMASS OF STEPPE BIOGEOCOENOSES AND AGROCOENOSES IN KHERSON REGION

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Shcherbina V.V.

2011-12-01

Full Text Available Characteristics of daily dynamics of seaweeds abundance and biomass were determined for steppe biogeocoenosis and agrocoenosis of Biosphere reserve “Askaniya-Nova” in spring of 2011. Fluctuation ranges in seaweeds abundance and biomass have been registered.Analyzing the indices of total number and algae biomass in studied biogeocoenoses it should be noted that the maximal values of alga number in virgin soil steppe exceeded minimal in 3,3 times; biomasses - in 2,1. For virgin soil steppe of post-fire-induced development the relation between maximum and minimal value of total number of algae was up to 2,1; biomass - 2,4. For agrocoenosis we noted the largest ranges in variation of number and biomass. In conditions of dry-land arable land the maximum values of total number of alga exceeded minimal in 21,9 times; biomasses - in 8,7; for irrigated arable land - in 12,5 and 5,6 respectively.In soil samples, selected within the limits of virgin soil biogeocoenoses of biosphere reserve “Askania-Nova” and agrocoenosis of dry-land and irrigated arable land in biosphere reserve by direct count, the algae species of Bacillariophyta, Cyanophyta, Chlorophyta, Xanthophyta and Eustigmatophyta have been found. The largest contribution to number and biomass of algae belonged to Bacillariophyta. The number and biomass of agrocoenosis algae is more dynamic feature, than for algae of virgin soil biogeocoenoses.

Evaluating the outcomes of the STEPPS programme in a UK community-based population; implications for the multidisciplinary treatment of borderline personality disorder.

Science.gov (United States)

Hill, N; Geoghegan, M; Shawe-Taylor, M

2016-08-01

WHAT IS KNOWN ON THE SUBJECT?: Individuals with a diagnosis of Borderline Personality Disorder (BPD) now constitute a substantial portion of the caseload for community teams. Specialized treatments for BPD often consume a large portion of available psychology resources and also involve lengthy waiting lists. The STEPPS programme is a treatment approach which is growing in evidence, particularly in the US. However, further evidence for the effectiveness of this programme within the UK healthcare system is needed. The results of this study support the preliminary evidence for the effectiveness of STEPPS in a UK community-based population. A reduction in symptom severity was in evidence. Novel measures were used to build on previous evaluations of the STEPPS programme. These measures show a significant reduction in patients' affinity for unhelpful schemas, as well as an increase in patients' self-reported quality of life; an important perspective for a recovery focused approach to treatment. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: The STEPPS programme has shown its merit as an effective and more accessible treatment option for the community-based treatment of BPD, though some methodological limitations are noted. Furthermore, the results of this study demonstrate that STEPPS can be delivered effectively by teams of facilitators from different professional backgrounds who do not necessarily have extensive training in psychotherapeutic interventions. The result is a well-rounded and diverse skill set possessed by the team of facilitators, adding to the richness of the patient's recovery journey and leading to a more favourable spread of teams' resources. Aims & Background Systems Training for Emotional Predictability and Problem Solving (STEPPS) is a group treatment for individuals with a diagnosis of Borderline Personality Disorder (BPD) which has a growing evidence base, particularly in the US. Evidence is sparse for its use with UK populations, and this study seeks

Targeted grazing for the restoration of sub-alpine shrub-encroached grasslands

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Massimiliano Probo

2016-12-01

Full Text Available The decline of agro-pastoral activities has led to a widespread tree and shrub-encroachment of former semi-natural meso-eutrophic grasslands in many European mountain regions. Temporary night camp areas (TNCA and mineral mix supplements for targeted cattle were arranged over shrub-encroached areas to restore grassland vegetation within the Val Troncea Natural Park (Italy. From 2011 to 2015, their effects on vegetation structure and pastoral value of forage were assessed along permanent transects. Four years after treatments, both practices were effective in reducing the shrub cover and increasing the cover and average height of the herbaceous layer, but changes were more remarkable within TNCA. Moreover, the arrangement of TNCA decreased the cover of nanophanerophytes and increased the cover of graminoids and high quality species, as well as the overall forage pastoral value. In conclusion, TNCA were the most effective pastoral practice to contrast shrub-encroachment and increase herbage mass and forage quality of sub-alpine grasslands.

Sulfidogenesis in hypersaline chloride-sulfate lakes of Kulunda Steppe (Altai, Russia)

NARCIS (Netherlands)

Sorokin, D.Y.; Zacharova, E.E.; Pimenov, N.V.; Tourova, T.P.; Panteleeva, A.N.; Muyzer, G.

2012-01-01

The activity and culturable diversity of sulfidogens were investigated in anoxic sediments of four hypersaline lakes with pH 7.6-8.2 in the Kulunda Steppe (Altai, Russia). Sulfate reduction rates were low, varying from 0.1 to 6.0 nmol HS−/(cm3 h) with a maximum in the top 10 cm layer. Potential

Throughfall and its spatial variability beneath xerophytic shrub canopies within water-limited arid desert ecosystems

Science.gov (United States)

Zhang, Ya-feng; Wang, Xin-ping; Hu, Rui; Pan, Yan-xia

2016-08-01

Throughfall is known to be a critical component of the hydrological and biogeochemical cycles of forested ecosystems with inherently temporal and spatial variability. Yet little is understood concerning the throughfall variability of shrubs and the associated controlling factors in arid desert ecosystems. Here we systematically investigated the variability of throughfall of two morphological distinct xerophytic shrubs (Caragana korshinskii and Artemisia ordosica) within a re-vegetated arid desert ecosystem, and evaluated the effects of shrub structure and rainfall characteristics on throughfall based on heavily gauged throughfall measurements at the event scale. We found that morphological differences were not sufficient to generate significant difference (P < 0.05) in throughfall between two studied shrub species under the same rainfall and meteorological conditions in our study area, with a throughfall percentage of 69.7% for C. korshinskii and 64.3% for A. ordosica. We also observed a highly variable patchy pattern of throughfall beneath individual shrub canopies, but the spatial patterns appeared to be stable among rainfall events based on time stability analysis. Throughfall linearly increased with the increasing distance from the shrub base for both shrubs, and radial direction beneath shrub canopies had a pronounced impact on throughfall. Throughfall variability, expressed as the coefficient of variation (CV) of throughfall, tended to decline with the increase in rainfall amount, intensity and duration, and stabilized passing a certain threshold. Our findings highlight the great variability of throughfall beneath the canopies of xerophytic shrubs and the time stability of throughfall pattern among rainfall events. The spatially heterogeneous and temporally stable throughfall is expected to generate a dynamic patchy distribution of soil moisture beneath shrub canopies within arid desert ecosystems.

Hydraulic lift through transpiration suppression in shrubs from two arid ecosystems: patterns and control mechanisms.

Science.gov (United States)

Prieto, Iván; Martínez-Tillería, Karina; Martínez-Manchego, Luis; Montecinos, Sonia; Pugnaire, Francisco I; Squeo, Francisco A

2010-08-01

Hydraulic lift (HL) is the passive movement of water through the roots from deep wet to dry shallow soil layers when stomata are closed. HL has been shown in different ecosystems and species, and it depends on plant physiology and soil properties. In this study we explored HL patterns in several arid land shrubs, and developed a simple model to simulate the temporal evolution and magnitude of HL during a soil drying cycle under relatively stable climatic conditions. This model was then used to evaluate the influence of soil texture on the quantity of water lifted by shrubs in different soil types. We conducted transpiration suppression experiments during spring 2005 in Chile and spring 2008 in Spain on five shrub species that performed HL, Flourensia thurifera, Senna cumingii and Pleocarphus revolutus (Chile), Retama sphaerocarpa and Artemisia barrelieri (Spain). Shrubs were covered with a black, opaque plastic fabric for a period of 48-72 h, and soil water potential was recorded at different depths under the shrubs. While the shrubs remained covered, water potential continuously increased in shallow soil layers until the cover was removed. The model output indicated that the amount of water lifted by shrubs is heavily dependent on soil texture, as shrubs growing in loamy soils redistributed up to 3.6 times more water than shrubs growing on sandy soils. This could be an important consideration for species growing in soils with different textures, as their ability to perform HL would be context dependent.

Study on the Method of Grass Yield Model in the Source Region of Three Rivers with Multivariate Data

International Nuclear Information System (INIS)

You, Haoyan; Luo, Chengfeng; Liu, Zhengjun; Wang, Jiao

2014-01-01

This paper uses remote sensing and GIS technology to analyse the Source Region of Three Rivers (SRTR) to establish a grass yield estimation model during 2010 with remote sensing data, meteorological data, grassland type data and ground measured data. Analysis of the correlation between ground measured data, vegetation index based HJ-1A/B satellite data, meteorological data and grassland type data were used to establish the grass yield model. The grass yield model was studied by several statistical methods, such as multiple linear regression and Geographically Weighted Regression (GWR). The model's precision was validated. Finally, the best model to estimate the grass yield of Maduo County in SRTR was contrasted with the TM degraded grassland interpretation image of Maduo County from 2009. The result shows that: (1) Comparing with the multiple linear regression model, the GWR model gave a much better fitting result with the quality of fit increasing significantly from less than 0.3 to more than 0.8; (2) The most sensitive factors affecting the grass yield in SRTR were precipitation from May to August and drought index from May to August. From calculation of the five vegetation indices, MSAVI fitted the best; (3) The Maduo County grass yield estimated by the optimal model was consistent with the TM degraded grassland interpretation image, the spatial distribution of grass yield in Maduo County for 2010 showed a ''high south and low north'' pattern

Food habits of Pacific Marten from scats in south-central Oregon

Science.gov (United States)

Randall J Wilk; Martin G Raphael

2017-01-01

Quantifying prey taken by Pacific Marten (Martes americana caurina) helps to understand local habitat requirements of the species. We collected 250 scat samples associated with at least 53 marten in a salvage-logged Lodgepole Pine (Pinus contorta)-Bitterbrush shrub (Purshia tridentata) forest in south-...

Shrub expansion at the forest–tundra ecotone: spatial heterogeneity linked to local topography

International Nuclear Information System (INIS)

Ropars, P; Boudreau, S

2012-01-01

Recent densification of shrub cover is now documented in many Arctic regions. However, most studies focus on global scale responses, yielding very little information on the local patterns. This research aims to quantify shrub cover increase at northern treeline (Québec, Canada) in two important types of environment, sandy terraces and hilltops (which cover about 70% of the landscape), and to identify the species involved. The comparison of a mosaic of two aerial photographs from 1957 (137 km 2 ) and one satellite image taken in 2008 (151 km 2 ) revealed that both hilltops and terraces recorded an increase in shrub cover. However, the increase was significantly greater on terraces than on hilltops (21.6% versus 11.6%). According to ground truthing, the shrub cover densification is associated mainly with an increase of Betula glandulosa Michx. The numerous seedlings observed during the ground truthing suggest that shrub densification should continue in the future. (letter)

Radial growth and percent of latewood in Scots pine provenance trials in Western and Central Siberia

Directory of Open Access Journals (Sweden)

S. R. Kuzmin

2016-12-01

Full Text Available Percent of latewood of Boguchany and Suzun Scots pine climatypes has been studied in two provenance trials (place of origin and trial place. For Boguchany climatype the place of origin is south taiga of Central Siberia (Krasnoyarsk Krai, the place of trial is forest-steppe zone of Western Siberia (Novosibirsk Oblast and vice versa for Suzun climatype – forest-steppe zone of Western Siberia is the place of origin, south taiga is the place of trial. Comparison of annual average values of latewood percent of Boguchany climatype in south taiga and forest-steppe revealed the same numbers – 19 %. Annual variability of this trait in south taiga is distinctly lower and equal to 17 %, in forest-steppe – 35 %. Average annual values of latewood percent of Suzun climatype in the place of origin and trial place are close (20 and 21 %. Variability of this trait for Suzun climatype is higher than for Boguchany and equal to 23 % in south taiga and 42 % in forest-steppe. Climatic conditions in southern taiga in Central Siberia in comparison with forest-steppe in Western Siberia make differences between climatypes stronger. Differences between climatypes are expressed in different age of maximal increments of diameter, different tree ring width and latewood percent values and in different latewood reaction to weather conditions.

Assessing effect of rainfall on rate of alien shrub expansion in a southern African savanna

NARCIS (Netherlands)

Masocha, Mhosisi; Dube, Timothy; Skidmore, A.K.; Holmgren, Milena; Prins, Herbert

2017-01-01

Understanding the environmental factors governing the spread of alien shrubs is crucial for conserving biodiversity. In the semi-arid savannas of Africa, alien shrub invasion often occurs simultaneously with native shrub encroachment but climate-dependent differences in encroachments of native and

MODEL RECONSTRUCTION OF THE VEGETATION COVER OF THE SOUTH OF THE WEST SIBERIAN PLAIN FROM THE LATE PALEOLITHIC PERIOD UNTIL THE LATE XIX CENTURY

Directory of Open Access Journals (Sweden)

М. А. Kharitonenkov

2016-06-01

Full Text Available Model reconstruction of vegetation cover of the south of the West Siberian Plain from the late Pleistocene to the modern era has been carried out on the basis of the associated chronological analysis of paleontological, archaeological and paleoclimate data. We have determined the starting point of active vegetation transformation in the south of the West Siberian Plain as a result of tradition-bound exploitation of natural resources. Periods of maximum anthropogenic load – peak and relative recession – on vegetation cover, acting as a further determinant factor, have been determined in this study for the first time. Comprehensive analysis and new understanding of palynological, paleozoological, archaeological and paleoclimate data in terms of theoretical synecology confirmed the notions on the determinant role of the anthropogenic factor in the transformation of the Pleistocene forest-meadow-steppe vegetation into contemporary communities of the southern taiga, the subtaiga and the forest-steppe of the West Siberian Plain.

Ground biomass assessment of shrub species in tehsil takht-e-nasrati, pakistan

International Nuclear Information System (INIS)

Khan, M.; Hussain, F.; Musharaf, S.; Musharaf, S.

2014-01-01

The shrub biomass of different species of Tehsil Takht-e-Nasrati was different at different altitude. In the present study it was found that the average shrub biomass was decreasing with increasing altitude. Result confirms that the biomass of Saccharum bengalense was high 5020.38 Kg.hec/sup -1/ in phase 1 and phase 2 (4331.58 Kg.hec/sup -1/). The highest ground biomass 1125.1 Kg.hec/sup -1/ of Zizyphus nummularia was found in Phase 3. Furthermore in Phase 4 the biomass of Capparis deciduas was high 437.79 Kg.hec/sup -1/. Along with shrubs average biomass of Saccharum bengalense was high 2665.12 Kg.hec/sup -1/ and low 13.47 Kg.hec/sup -1/ of Cassia angustifolia. With seasons the biomass of Saccharum bengalense (13800 Kg.hec/sup -1/) was greater during winter at Phase 1 and Periploc aaphylla (12.35 Kg.hec-1) biomass was lowers during spring at Phase 4. In comparison in season the biomass was high in winter due to the dormant stage of shrubs in phase 1 while it was low in summer in phase 4. In winter the grazing process was stop due to agriculture point of view while in hilly area the grazing was high and the low percentage of rain fall consequently the biomass was high in plain area as contrast to hilly area. The biomass of shrubs is high in winter while it was low in summer as the grazing and palatability rate was high in summer as well as low in winter. The assessment of shrub biomass in research area is a requirement for successful management at the same time as it gives a complete documentation for the area in complexity and work out unpredictable resources to help imagine shrubs potency and behavior. (author)

Analysis of the soil food web structure under grass and grass clover

NARCIS (Netherlands)

Eekeren, van N.J.M.; Smeding, F.W.; Vries, de F.T.; Bloem, J.

2006-01-01

The below ground biodiversity of soil organisms plays an important role in the functioning of the the soil ecosystem, and consequently the above ground plant production. The objective of this study is to investigate the effect of grass or grass-clover in combination with fertilisation on the soil

Linear objects impact on grassland degradation in the typical steppe region of China

NARCIS (Netherlands)

Li, Suying; Verburg, Peter H.; Lv, Shihai; Gao, Shangyu; Wu, Jingle

2011-01-01

Despite growing recognition of the issue of grassland degradation, few regional estimates of linear object impacts on grassland degradation [1]. We presented a methodology for evaluating regional impacts on steppe degradation from linear objects which were two uppermost types, rivers and roads, in

Evaluation of revegetation techniques of a saline flue gas desulfurization sludge pond

Energy Technology Data Exchange (ETDEWEB)

Salo, L.F.; Artiola, J.F.; Goodrich-Mahoney, J.W. [University of Arizona, Tucson, AZ (United States). Renewable National Resources

1999-01-01

Codisposal of flue gas desulfurization (FGD) sludge with low-volume generating station waste simplifies disposal but creates a saline, high boron (B) waste that may be difficult to revegetate after site closure. Studies on a delta of waste material in a codisposal pond at the coal-fired Coronado Generating Station in eastern Arizona evaluated management techniques, amendments, and plants for revegetating this material. One study investigated leaching and ridging techniques and a second evaluated amendment with manure, wood shavings, and fly ash, Four salt-tolerant grass species and four saltbushes (A triplex spp,) were evaluated in the two studies. Criteria for success were high survival rates and growth, as measured by grass height and shrub height x width. Leaching salts and B from the waste was not necessary for establishment and growth of transplanted shrubs and grasses. Ridging was not a successful technique, due to limited moisture and high levels of salinity and B on these structures. Gardner saltbush (A, gardneri (Moq.) D, Dietr.) and a fourwing saltbush (A. canescens (Pursh) Nutt,) accession from the site were the most successful shrubs and alkali sactonn (Sporobolus airoides (Torr,) Torr. `Saltalk`) was the most successful grass at this disposal pond. Amendment with manure, wood shavings, or fly ash did not increase plant survival. Growth of grasses was improved with all amendments and was greatest with manure, but growth of shrubs was not improved with any amendment. 33 refs., 8 tabs.

Scrub-shrub bird habitat associations at multiple spatial scales in beaver meadows in Massachusetts

Science.gov (United States)

Chandler, R.B.; King, D.I.; DeStefano, S.

2009-01-01

Most scrub-shrub bird species are declining in the northeastern United States, and these declines are largely attributed to regional declines in habitat availability. American Beaver (Castor canadensis; hereafter “beaver”) populations have been increasing in the Northeast in recent decades, and beavers create scrub-shrub habitat through their dam-building and foraging activities. Few systematic studies have been conducted on the value of beaver-modified habitats for scrub-shrub birds, and these data are important for understanding habitat selection of scrub-shrub birds as well as for assessing regional habitat availability for these species. We conducted surveys in 37 beaver meadows in a 2,800-km2 study area in western Massachusetts during 2005 and 2006 to determine the extent to which these beaver-modified habitats are used by scrub-shrub birds, as well as the characteristics of beaver meadows most closely related to bird use. We modeled bird abundance in relation to microhabitat-, patch-, and landscape-context variables while adjusting for survey-specific covariates affecting detectability using N-mixture models. We found that scrub-shrub birds of regional conservation concern occupied these sites and that birds responded differently to microhabitat, patch, and landscape characteristics of beaver meadows. Generally, scrub-shrub birds increased in abundance along a gradient of increasing vegetation complexity, and three species were positively related to patch size. We conclude that these habitats can potentially play an important role in regional conservation of scrub-shrub birds and recommend that conservation priority be given to larger beaver meadows with diverse vegetation structure and composition.

Bread winter wheat breeding (Triticum aestivum L. using spring varieties genepool in forest-steppe Environments of Ukraine

Directory of Open Access Journals (Sweden)

В. С. Кочмарський

2010-10-01

Full Text Available It is concluded by investigations that wheat crossing of various development types between themselves cause increase of formbuilding process in hybrid progeny, promoting the selection of practically valuable recombinats. The genotypes which present the practical valuable by complex of adaptive traits and properties have been selected by phenotype stability in the breeding process. The new bread winter wheat variety Pamyati Remesla developed with participation of spring wheat variety Hja 22139 (Finland has been proposed for including it into the Register of Plant varieties of Ukraine adapted for use in Steppe, Forest- Steppe and Woodland of Ukraine since 2010.

The Relationship between an Invasive Shrub and Soil Moisture: Seasonal Interactions and Spatially Covarying Relations

Directory of Open Access Journals (Sweden)

Yuhong He

2014-09-01

Full Text Available Recent studies indicate that positive relationships between invasive plants and soil can contribute to further plant invasions. However, it remains unclear whether these relations remain unchanged throughout the growing season. In this study, spatial sequences of field observations along a transect were used to reveal seasonal interactions and spatially covarying relations between one common invasive shrub (Tartarian Honeysuckle, Lonicera tatarica and soil moisture in a tall grassland habitat. Statistical analysis over the transect shows that the contrast between soil moisture in shrub and herbaceous patches vary with season and precipitation. Overall, a negatively covarying relationship between shrub and soil moisture (i.e., drier surface soils at shrub microsites exists during the very early growing period (e.g., May, while in summer a positively covarying phenomenon (i.e., wetter soils under shrubs is usually evident, but could be weakened or vanish during long precipitation-free periods. If there is sufficient rainfall, surface soil moisture and leaf area index (LAI often spatially covary with significant spatial oscillations at an invariant scale (which is governed by the shrub spatial pattern and is about 8 m, but their phase relation in space varies with season, consistent with the seasonal variability of the co-varying phenomena between shrub invasion and soil water content. The findings are important for establishing a more complete picture of how shrub invasion affects soil moisture.

Water and Nitrogen Limitations of Ecosystem Processes Across Three Dryland Plant Communities

Science.gov (United States)

Beltz, C.; Lauenroth, W. K.; Burke, I. C.

2017-12-01

The availability of water and nitrogen (N) play a major role in controlling the distribution of ecosystem types and the rates of ecosystem processes across the globe. Both these resources are being altered by human activity. Anthropogenic fixation of N has increased inputs into the biosphere from 0.5 kg N ha-1 yr-1 to upwards of 10 kg N ha-1 yr-1, while the amount and seasonality of precipitation are expected to continue to change. Within dryland environments, the relationships between increasingly available N and ecosystem processes are especially complex due to dryland's characteristic strong limitation by low and highly variable precipitation. Other experiments have shown that this interplay between N and water can cause temporally complex co-limitation and spatially complex responses with variable effects on ecosystems, such as those to net primary productivity, soil respiration, and plant community composition. Research spanning multiple dryland plant communities is critical for generalizing findings to the 40% of the Earth's terrestrial surface covered in dryland ecosystems. Given IPCC projections in which both N availability and precipitation are altered, examining their interactive effect across multiple plant communities is critical to increasing our understanding of the limitations to ecosystem process in drylands. We are studying a gradient of three plant communities representing a C4 grassland (shortgrass steppe), a C3/C4 grassland (mixed grass prairie), and a shrub-dominated ecosystem with C3 and C4 grasses (sagebrush steppe). We added two levels of N (10 kg N ha-1 and 100 kg N ha-1) and increased summer monthly precipitation by 20%. Sites responded differently to treatments, with the scale of effect varying by treatment. The high-level nitrogen increased soil N availability and soil respiration, while decreasing soil carbon in the labile pool in the upper soil layers. These results will allow for better understanding of increased N in combination with

Indole-diterpenes and ergot alkaloids in Cynodon dactylon (Bermuda grass) infected with Claviceps cynodontis from an outbreak of tremors in cattle.

Science.gov (United States)

Uhlig, Silvio; Botha, Christo J; Vrålstad, Trude; Rolén, Elin; Miles, Christopher O

2009-12-09

Tremorgenic syndromes in mammals are commonly associated with indole-diterpenoid alkaloids of fungal origin. Cattle are sometimes affected by tremors (also called "staggers") when they graze on toxic grass pastures, and Bermuda grass ( Cynodon dactylon , kweek) has been known to be associated with tremors for several decades. This study reports the identification of paspalitrems and paspaline-like indole-diterpenes in the seedheads of Claviceps cynodontis -infected Bermuda grass collected from a pasture that had caused a staggers syndrome in cattle in South Africa and thereby links the condition to specific mycotoxins. The highest concentration (about 150 mg/kg) was found for paspalitrem B. Ergonovine and ergine (lysergic acid amide), together with their C-8 epimers, were found to co-occur with the indole-diterpenes at concentrations of about 10 microg/kg. The indole-diterpene profile of the extract from the ergotized Bermuda grass was similar to that of Claviceps paspali sclerotia. However, the C. paspali sclerotia contained in addition agroclavine and elymoclavine. This is the first study linking tremors associated with grazing of Bermuda grass to specific tremorgenic indole-diterpenoid mycotoxins.

Estimating shrub biomass from basal stem diameters

Energy Technology Data Exchange (ETDEWEB)

Brown, J K

1976-01-01

Stem lengths and oven dry wt of stemwood and foilage were determined for shrubs in dia classes of 0 to 0.5 cm, 0.5 to 2 cm and 2 to 5 cm in various habitat types in Idaho and Montana. The logarithm of basal stem dia was closely correlated with the logarithm of wt. Regression components are presented for estimating leaf wt and total above-ground wt of 25 woody shrub species using a linear equation relating these 2 variables. Percentage stemwood wt is given for the 3 dia classes. Dia distributions for the smallest dia class were normal except for a few species with fine twigs; distributions for the other classes were positively skewed. Applications to forest fuel studies are briefly discussed.

Estimating shrub biomass from basal stem diameters

Energy Technology Data Exchange (ETDEWEB)

Brown, J K

1976-01-01

Stem lengths and oven dry wt of stemwood and foilage were determined for shrubs in dia classes of 0 to 0.5 cm, 0.5 to 2 cm and 2 to 5 cm in various habitat types in Idaho and Montana. The logarithm of basal stem dia was closely correlated with the logarithm of wt. Regression components are presented for estimating leaf wt and total above-ground wt of 25 woody shrub species using a linear equation relating these 2 variables. Percentage stemwood wt is given for the 3 dia classes. Dia distributions for the smallest dia class were normal except for a few species with fine twigs: distributions for the other classes were positively skewed. Applications to forest fuel studies are briefly discussed.

Changes in Biomass and Quality of Alpine Steppe in Response to N & P Fertilization in the Tibetan Plateau

Science.gov (United States)

Dong, Junfu; Cui, Xiaoyong; Wang, Shuping; Wang, Fang; Pang, Zhe; Xu, Ning; Zhao, Guoqiang; Wang, Shiping

2016-01-01

In the alpine steppe zone on the Central Tibetan Plateau, a large amount of area has been degraded due to natural and artificial factors. N & P fertilization is widely accepted to recover degraded pastures in other regions all over the world. However, it is not clear how alpine steppe communities respond to N & P fertilization, and what is the optimal application rate, in the perspective of forage production. To attempt to explore these questions, in July 2013, two fencing sites were designed in Baingoin County with 12 treatments of different levels of nitrogen (N0: 0; N1: 7.5 g m-2 yr-1; N2: 15 g m-2 yr-1) & phosphate (P0: 0; P1: 7.5 gP2O5 m-2 yr-1; P2: 15 gP2O5 m-2 yr-1; P3: 30 gP2O5 m-2 yr-1). The results indicated N&P addition was capable to ameliorate the quality of the two sites in the Tibetan Plateau steppe. Increasing N application level resulted in significant increment in Gramineae and total biomass in the two sites. P addition significantly improved the quantity of Compositae, total biomass and the biomasss of other species in site II, while it only significantly improved the total biomass in site I. Gramineae was much more sensitive to N-induced changes than P-induced changes, and this indicated N addition was better to ameliorate the quality of plateau steppe than P-induced changes. No strong evidence was found for critical threshold within 15 g N m-2 yr-1, and there was decreasing tendency when P addition rate was above 15 g m-2 yr-1. N&P has the potential to accelerate soil acidification, which improved the content of available K, likely as a result of nonsignificant correlation between biomass and soil moisture. This work highlights the the tradeoffs that exist in N and P addition in recovering degraded steppe. PMID:27223104

Population status, habitat associations, and distribution of the steppe polecat Mustela eversmanii in Europe

Czech Academy of Sciences Publication Activity Database

Šálek, Martin; Spassov, N.; Anděra, M.; Enzinger, K.; Ottlecz, B.; Hegyeli, Z.

2013-01-01

Roč. 58, č. 3 (2013), s. 233-244 ISSN 0001-7051 Institutional support: RVO:68081766 Keywords : Steppe polecat * Mustela eversmanii * Distribution * Habitat associations * Population status * Europe Subject RIV: EG - Zoology Impact factor: 1.161, year: 2013

Meadow-grass gall midge

DEFF Research Database (Denmark)

Hansen, Lars Monrad

The area with meadow-grass (Poa pratensis, L.) grown for seed production in Den-mark is a significant proportion of the entire seed production. The meadow-grass gall midge (Mayetiola schoberi, Barnes 1958) is of considerable economic importance since powerful attacks can reduce the yield...

Yield and grain quality of winter wheat under Southern Steppe of Ukraine growing conditions

Directory of Open Access Journals (Sweden)

М. М. Корхова

2014-12-01

Full Text Available The results of three years study of the effect of sowing time and seed application rates on yield and grain quality of different varieties of winter wheat under the conditions of South Steppe of Ukraine were presented. It was found that winter wheat provides optimal combination of high yield and grain quality in case of sowing in October 10 with seed application rate of 5,0 million seeds/ha. The highest yield – 4,59 t/ha on average in 2011–2013 was obtained for the variety of Natalka when sowing in October 10 with seed application rate  of 5 million germinable seeds. With increasing seed application rate from 3 to 5 million seeds/ha, protein content in winter wheat was decreased by 0,3%, gluten – by 0,6%. The variety Natalka  formed the highest quality grains when sowing in October 20 with seed application rate of 3 million seeds/ha, in this case protein content was 15,8%, gluten – 32,9%. It is proved that early sowing time  – September 10 leads to yields reduction and grain   quality deterioration for all winter wheat varieties.

Habitat, food, and small mammal community structure in Namaqualand

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M. van Deventer

2006-12-01

Full Text Available The effect of habitat differences and food availability on small mammal (rodent and elephant shrew species richness, diversity, density and biomass was investigated in Namaqualand, South Africa. Species richness in the three habitats sampled, namely Upland Succulent Karoo, Dry Riverine Shrub and North-western Mountain Renosterveld was low, with only 2–4 species per habitat. Rodents trapped were predominantly Gerbillurus paeba and Aethomys namaquensis, with fewer Mus minutoides and Petromyscus sp. The only non-rodent was the elephant shrew Elephantulus edwardii. Ten habitat features, the percentage of total plant cover, tree cover, shrub cover, grass cover, plant litter, total basal cover, sand, gravel or rock cover, and the dominant plant height were recorded at 30 randomly chosen points on five sampling grids in each habitat. Small mammal density and biomass was significantly correlated with food availability (green foliage cover, seeds, and relative density and biomass of insects. Species richness and diversity of small mammals were significantly correlated with shrub cover. Numbers and biomass of specific species correlated significantly with different habitat features in each case.

Biomorphological traits of Callistephus chinensis (L. Nees cultivars under conditions of the Central Forest-Steppe zone of Ukraine

Directory of Open Access Journals (Sweden)

С. М. Левандовська

2015-12-01

Full Text Available Purpose. Determining prospects of introducing Callistephus chinensis cultivars of foreign breeding for further cultivation under conditions of the Central Forest-Steppe zone of Ukraine. Methods. Field, laboratory, analytical and statistical ones. Results. Ten C. сhinensis cultivars of theGerman breeding were tested under conditions of the Central Forest-Steppe zone of Ukraine. Biomorphological traits of the varieties of five sort types were identified, and their comparative analysis was conducted. Seasonal dynamics of growth and development of cultivars in the growing area was studied. Conclusions. Cultivars with short and mean duration phases of development can be grown under conditions of the Central Forest-Steppe zone of Ukraine by direct sowing that does not affect their seed productivity and sowing quality of seeds. Seeds of late cultivars can reach complete maturity only in case of seedling use. C. chinensis cultivars of the German breeding have successfully passed the initial test for suitability to introduction into the studied area.

Fire tolerance of a resprouting Artemisia (Asteraceae) shrub

Science.gov (United States)

Winter, S.L.; Fuhlendorf, S.D.; Goad, C.L.; Davis, C.A.; Hickman, K.R.; Leslie, David M.

2011-01-01

In North America, most Artemisia (Asteraceae) shrub species lack the ability to resprout after disturbances that remove aboveground biomass. We studied the response of one of the few resprouting Artemisia shrubs, Artemisia filifolia (sand sagebrush), to the effects of prescribed fires. We collected data on A. filifolia density and structural characteristics (height, canopy area, and canopy volume) in an A. filifolia shrubland in the southern Great Plains of North America. Our study sites included areas that had not been treated with prescribed fire, areas that had been treated with only one prescribed fire within the previous 5 years, and areas that had been treated with two prescribed fires within the previous 10 years. Our data were collected at time periods ranging from 1/2 to 5 years after the prescribed fires. Density of A. filifolia was not affected by one or two fires. Structural characteristics, although initially altered by prescribed fire, recovered to levels characteristic of unburned areas in 3-4 years after those fires. In contrast to most non-sprouting North American Artemisia shrub species, our research suggested that the resprouting A. filifolia is highly tolerant to the effects of fire. ?? 2011 Springer Science+Business Media B.V.

Estimating grass and grass silage degradation characteristics by in situ and in vitro gas production methods

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Danijel Karolyi

2010-01-01

Full Text Available Fermentation characteristics of grass and grass silage at different maturities were studied using in situ and in vitro gas production methods. In situ data determined difference between grass and silage. Degradable fraction decreased as grass matured while the undegradable fraction increased. Rate of degradation (kd was slower for silage than fresh grass. Gas production method (GP data showed that fermentation of degradable fraction was different between stage of maturity in both grass and silage. Other data did not show any difference with the exception for the rate of GP of soluble and undegradable fraction. The in situ degradation characteristics were estimated from GP characteristics. The degradable and undegradable fractions could be estimated by multiple relationships. Using the three-phases model for gas production kd and fermentable organic matter could be estimated from the same parameters. The only in situ parameter that could not be estimated with GP parameters was the soluble fraction. The GP method and the three phases model provided to be an alternative to the in situ method for animal feed evaluations.

High green fodder yielding new grass varieties

OpenAIRE

C. Babu, K. Iyanar and A. Kalamani

2014-01-01

Two high biomass yielding forage grass varieties one each in Cumbu Napier hybrid and Guinea grass have been evolved at the Department of Forage Crops, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore and identified for release at national (All India) level as Cumbu Napier hybrid grass CO (BN) 5 and Guinea grass CO (GG) 3 during 2012 and 2013 respectively. Cumbu Napier hybrid grass CO (BN) 5 secured first rank at all national level with reference to green ...

Munroa argentina, a Grass of the South American Transition Zone, Survived the Andean Uplift, Aridification and Glaciations of the Quaternary.

Directory of Open Access Journals (Sweden)

Leonardo D Amarilla

Full Text Available The South American Transition Zone (SATZ is a biogeographic area in which not only orogeny (Andes uplift and climate events (aridification since the mid-Miocene, but also Quaternary glaciation cycles had an important impact on the evolutionary history of the local flora. To study this effect, we selected Munroa argentina, an annual grass distributed in the biogeographic provinces of Puna, Prepuna and Monte. We collected 152 individuals from 20 localities throughout the species' range, ran genetic and demographic analyses, and applied ecological niche modeling. Phylogenetic and population genetic analyses based on cpDNA and AFLP data identified three phylogroups that correspond to the previously identified subregions within the SATZ. Molecular dating suggests that M. argentina has inhabited the SATZ since approximately 3.4 (4.2-1.2 Ma and paleomodels predict suitable climate in these areas during the Interglacial period and the Last Glacial Maximum. We conclude that the current distribution of M. argentina resulted from the fragmentation of its once continuous range and that climate oscillations promoted ecological differences that favored isolation by creating habitat discontinuity.

Munroa argentina, a Grass of the South American Transition Zone, Survived the Andean Uplift, Aridification and Glaciations of the Quaternary

Science.gov (United States)

Amarilla, Leonardo D.; Anton, Ana M.; Chiapella, Jorge O.; Manifesto, María M.; Angulo, Diego F.; Sosa, Victoria

2015-01-01

The South American Transition Zone (SATZ) is a biogeographic area in which not only orogeny (Andes uplift) and climate events (aridification) since the mid-Miocene, but also Quaternary glaciation cycles had an important impact on the evolutionary history of the local flora. To study this effect, we selected Munroa argentina, an annual grass distributed in the biogeographic provinces of Puna, Prepuna and Monte. We collected 152 individuals from 20 localities throughout the species’ range, ran genetic and demographic analyses, and applied ecological niche modeling. Phylogenetic and population genetic analyses based on cpDNA and AFLP data identified three phylogroups that correspond to the previously identified subregions within the SATZ. Molecular dating suggests that M. argentina has inhabited the SATZ since approximately 3.4 (4.2–1.2) Ma and paleomodels predict suitable climate in these areas during the Interglacial period and the Last Glacial Maximum. We conclude that the current distribution of M. argentina resulted from the fragmentation of its once continuous range and that climate oscillations promoted ecological differences that favored isolation by creating habitat discontinuity. PMID:26110533

Munroa argentina, a Grass of the South American Transition Zone, Survived the Andean Uplift, Aridification and Glaciations of the Quaternary.

Science.gov (United States)

Amarilla, Leonardo D; Anton, Ana M; Chiapella, Jorge O; Manifesto, María M; Angulo, Diego F; Sosa, Victoria

2015-01-01

The South American Transition Zone (SATZ) is a biogeographic area in which not only orogeny (Andes uplift) and climate events (aridification) since the mid-Miocene, but also Quaternary glaciation cycles had an important impact on the evolutionary history of the local flora. To study this effect, we selected Munroa argentina, an annual grass distributed in the biogeographic provinces of Puna, Prepuna and Monte. We collected 152 individuals from 20 localities throughout the species' range, ran genetic and demographic analyses, and applied ecological niche modeling. Phylogenetic and population genetic analyses based on cpDNA and AFLP data identified three phylogroups that correspond to the previously identified subregions within the SATZ. Molecular dating suggests that M. argentina has inhabited the SATZ since approximately 3.4 (4.2-1.2) Ma and paleomodels predict suitable climate in these areas during the Interglacial period and the Last Glacial Maximum. We conclude that the current distribution of M. argentina resulted from the fragmentation of its once continuous range and that climate oscillations promoted ecological differences that favored isolation by creating habitat discontinuity.

Shrub encroachment alters sensitivity of soil respiration to temperature and moisture 2115

Science.gov (United States)

Shrub encroachment into grasslands creates a mosaic of different soil microsites ranging from open spaces to well-developed shrub canopies, and it is unclear how this affects the spatial variability in soil respiration characteristics, such as the sensitivity to soil temperature and moisture. This i...

Enhancing GRASS data communication with videographic technology

Energy Technology Data Exchange (ETDEWEB)

Sullivan, R.G. [Argonne National Lab., IL (United States); Gerdes, D.; Youngs, D. [Army Construction Engineering Research Lab., Champaign, IL (United States)

1992-07-01

Research at Argonne National Laboratory and the US Army Construction Engineering Research Laboratory has shown that computer videographic technology can be used to assist visualization and communication of GIS-generated geographic information. Videographic tools can be used to make results of GRASS analyses clear to decision-makers and to public interest groups, as well as to help GRASS users visualize geographic data more easily. Useful videographic visualization tools include graphic overlay of GRASS layers onto panchromatic images, allowing landscape features to be associated with GIS classifications; draping of GIS layers onto terrain models to create shaded relief maps; and incorporation of photographic imagery into GIS graphics. Useful videographic communications capabilities include convenient, direct interface to video formats, allowing incorporation of live video into GRASS graphics and output of GRASS graphics to video; convenient output of high-quality slides and prints; and enhanced labeling and editing of GRASS images. Conversion of GRASS imagery to standard videographic file formats also facilitates incorporation of GRASS images into other software programs, such as database and work-processing packages.

Enhancing GRASS data communication with videographic technology

Energy Technology Data Exchange (ETDEWEB)

Sullivan, R.G. (Argonne National Lab., IL (United States)); Gerdes, D.; Youngs, D. (Army Construction Engineering Research Lab., Champaign, IL (United States))

1992-01-01

Research at Argonne National Laboratory and the US Army Construction Engineering Research Laboratory has shown that computer videographic technology can be used to assist visualization and communication of GIS-generated geographic information. Videographic tools can be used to make results of GRASS analyses clear to decision-makers and to public interest groups, as well as to help GRASS users visualize geographic data more easily. Useful videographic visualization tools include graphic overlay of GRASS layers onto panchromatic images, allowing landscape features to be associated with GIS classifications; draping of GIS layers onto terrain models to create shaded relief maps; and incorporation of photographic imagery into GIS graphics. Useful videographic communications capabilities include convenient, direct interface to video formats, allowing incorporation of live video into GRASS graphics and output of GRASS graphics to video; convenient output of high-quality slides and prints; and enhanced labeling and editing of GRASS images. Conversion of GRASS imagery to standard videographic file formats also facilitates incorporation of GRASS images into other software programs, such as database and work-processing packages.

Germination and seedling establishment of spiny hopsage in response to planting date and seedbed environment

Science.gov (United States)

Nancy L. Shaw; Marshall R. Haferkamp; Emerenciana G. Hurd

1994-01-01

Reestablishment of spiny hopsrge (Grayia spinosa [Hook.] Moq.) in the shrub steppe requires development of appropriate seeding technology. We examined the effect of planting date and seedbed environment on germination and seedling establishment of 2 seed sources at 2 southwestern Idaho sites. Seedbeds were prepared by rototilling. In 1987-88, seeds...

Wyoming big sagebrush: Efforts towards development of target plants for restoration

Science.gov (United States)

Kayla R. Herriman

2009-01-01

Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis) is a dominant shrub throughout much of the interior western United States. It is a key component of sagebrush steppe ecosystems, which have been degraded due to European settlement, improper land use, and changing fire regimes resulting from the invasion of exotic...

Plant-soil interactions promote co-occurrence of three nonnative woody shrubs.

Science.gov (United States)

Kuebbing, Sara E; Classen, Aimée T; Call, Jaime J; Henning, Jeremiah A; Simberloff, Daniel

2015-08-01

Ecosystems containing multiple nonnative plant species are common, but mechanisms promoting their co-occurrence are understudied. Plant-soil interactions contribute to the dominance of singleton species in nonnative ranges because many nonnatives experience stronger positive feedbacks relative to co-occurring natives. Plant-soil interactions could impede other nonnatives if an individual nonnative benefits from its soil community to a greater extent than its neighboring nonnatives, as is seen with natives. However, plant-soil interactions could promote nonnative co-occurrence if a nonnative accumulates beneficial soil mutualists that also assist other nonnatives. Here, we use greenhouse and field experiments to ask whether plant-soil interactions (1) promote the codominance of two common nonnative shrubs (Ligustrum sinense and Lonicera maackii) and (2) facilitate the invasion of a less-common nonnative shrub (Rhamnus davurica) in deciduous forests of the southeastern United States. In the greenhouse, we found that two of the nonnatives, L. maackii and R. davurica, performed better in soils conditioned by nonnative shrubs compared to uninvaded forest soils, which. suggests that positive feedbacks among co-occurring nonnative shrubs can promote continued invasion of a site. In both greenhouse and field experiments, we found consistent signals that the codominance of the nonnatives L. sinense and L. maackii may be at least partially explained by the increased growth of L. sinense in L. maackii soils. Overall, significant effects of plant-soil interactions on shrub performance indicate that plant-soil interactions can potentially structure the co-occurrence patterns of these nonnatives.

Virtual TeamSTEPPS(®) Simulations Produce Teamwork Attitude Changes Among Health Professions Students.

Science.gov (United States)

Sweigart, Linda I; Umoren, Rachel A; Scott, Patrician J; Carlton, Kay Hodson; Jones, James A; Truman, Barbara; Gossett, Evalyn J

2016-01-01

The majority of the estimated 400,000 or more patient deaths per year in the United States are from preventable medical errors due to poor communication. Team training programs have been established to teach teamwork skills to health professions students. However, it is often challenging to provide this training at a physical site. A brief intervention using a virtual learning environment with TeamSTEPPS(®)-based scenarios is described. Using a pretest-posttest design, the effects on teamwork attitudes in 109 health professional students from two institutions and multiple disciplines were measured using the TeamSTEPPS Teamwork Attitudes questionnaire. Participants showed significant attitude changes in the categories of leadership, situation monitoring, mutual support, and communication (p ⩽ .05), with significance in four of the six indicator attitudes in the communication section at the p ⩽ .001 level. These findings indicate the potential impact that virtual learning experiences may have on teamwork attitudes in learners across professions on multiple campuses. Copyright 2016, SLACK Incorporated.

Shrubs and vines for northeastern wildlife

Science.gov (United States)

John D. Gill; William M. Healy

1974-01-01

A non-technical handbook in which 34 authors discuss management of 97 native and 3 naturalized shrubs or woody vines most important to wildlife in the Northeast,-Kentucky to Maryland to Newfoundland to Ontario. Topics include range, habitat, life history, uses, propagation, and management; but not identification.

Impact of Precipitation Fluctuation on Desert-Grassland ANPP

Directory of Open Access Journals (Sweden)

Liangxu Liu

2016-11-01

Full Text Available Precipitation change has significantly influenced annual net primary productivity (ANPP at either annual or seasonal scales in desert steppes in arid and semi-arid regions. In order to reveal the process of precipitation driving ANPP at different time scales, responses of different ANPP levels to the inter-annual and intra-annual precipitation fluctuations were analyzed. ANPP was reversed by building a ground reflectance spectrum model, from 2000 to 2015, using the normalized differential vegetation index of the Moderate-Resolution Imaging Spectroradiometer (MODIS-NDVI data at 250 m × 250 m spatial resolution. Since the description of the differently expressing forms of precipitation are not sufficient in former studies in order to overcome the deficiency of former studies, in this study, intra-annual precipitation fluctuations were analyzed not only with precipitation of May–August, June–August, July–August, and August, respectively, which have direct influence on vegetation productivity within the year, but quantitative description, vector precipitation (R, concentration ratio (Cd, and concentration period (D, were also used to describe the overall characteristics of intra-annual precipitation fluctuations. The concentration ratio and the maximum precipitation period of the intra-annual precipitation were represented by using monthly precipitation. The results showed that: (1 in the period from 1971 to 2015, the maximum annual precipitation is 3.76 times that of the minimum in the Urat desert steppe; (2 vector precipitation is more significantly related to ANPP (r = 0.7724, p = 0.000 compared to meteorological annual precipitation and real annual precipitation influence; and (3 annual precipitation is almost concentrated in 5–8 months and monthly precipitation accumulation has significantly effected ANPP, especially in the period of June–August, since the vegetation composition in the study area was mainly sub-shrubs and perennial

Different techniques to study rumen fermentation characteristics of maturing grass and grass silage

NARCIS (Netherlands)

Cone, J.W.; Gelder, van A.H.; Soliman, I.A.; Visser, de H.; Vuuren, van A.M.

1999-01-01

Grass samples were harvested during the 1993 growing season after a precut on April 27, 1993 and were stored frozen or left to ensile in 30-L buckets. Effects on chemical composition and fermentation kinetics of the maturation of the grass and of ensiling were investigated. Chemical composition and

How did climate drying reduce ecosystem carbon storage in the forest-steppe ecotone? A case study in Inner Mongolia, China.

Science.gov (United States)

Zhang, Yuke; Liu, Hongyan

2010-07-01

The projected recession of forests in the forest-steppe ecotone under projected climate drying would restrict the carbon sink function of terrestrial ecosystems. Previous studies have shown that the forest-steppe ecotone in the southeastern Inner Mongolia Plateau originally resulted from climate drying and vegetation shifts during the mid- to late-Holocene, but the interrelated processes of changing soil carbon storage and vegetation and soil shifts remain unclear. A total of 44 forest soil profiles and 40 steppe soil profiles were excavated to determine soil carbon storage in deciduous broadleaf forests (DBF), coniferous forests (CF) and steppe (ST) in this area. Carbon density was estimated to be 106.51 t/hm(2) (DBF), 73.20 t/hm(2) (CF), and 28.14 t/hm(2) (ST) for these ecosystems. Soil organic carbon (SOC) content was negatively correlated with sand content (R = -0.879, P ecotone. Changes in carbon storage caused by climate drying can be divided into two stages: (1) carbon storage of the ecosystem was reduced to 68.7%, mostly by soil coarsening when DBF were replaced by CF at approximately 5,900 (14)C years before present (BP); and (2) carbon storage was reduced to 26.4%, mostly by vegetation shifts when CF were replaced by ST at approximately 2,900 (14)C years BP.

The Spatial Pattern and Interactions of Woody Plants on the Temperate Savanna of Inner Mongolia, China: The Effects of Alternating Seasonal Grazing-Mowing Regimes.

Directory of Open Access Journals (Sweden)

Xiao Wang

Full Text Available Ulmus pumila tree-dominated temperate savanna, which is distributed widely throughout the forest-steppe ecotone on the Mongolian Plateau, is a relatively stable woody-herbaceous complex ecosystem in northern China. Relatively more attention has been paid to the degradation of typical steppe areas, whereas less focus has been placed on the succession of this typical temperate savanna under the present management regime. In this study, we established 3 sample plots 100 m×100 m in size along a gradient of fixed distances from one herder's stationary site and then surveyed all the woody plants in these plots. A spatial point pattern analysis was employed to clarify the spatial distribution and interaction of these woody plants. The results indicated that old U. pumila trees (DBH ≥ 20 cm showed a random distribution and that medium U. pumila trees (5 cm ≤ DBH < 20 cm showed an aggregated distribution at a smaller scale and a random distribution at a larger scale; few or no juvenile trees (DBH < 5 cm were present, and seedlings (without DBH formed aggregations in all 3 plots. These findings can be explained by an alternate seasonal grazing-mowing regime (exclosure in summer, mowing in autumn and grazing in winter and spring; the shrubs in all 3 plots exist along a grazing gradient that harbors xerophytic and mesophytic shrubs. Of these shrubs, xerophytic shrubs show significant aggregation at a smaller scale (0-5.5 m, whereas mesophytic shrubs show significant aggregation at a larger scale (0-25 m, which may be the result of the dual effects of grazing pressure and climate change. Medium trees and seedlings significantly facilitate the distributions of xerophytic shrubs and compete significantly with mesophytic shrubs due to differences in water use strategies. We conclude that the implementation of an alternative grazing-mowing regime results in xerophytic shrub encroachment or existence, breaking the chain of normal succession in a U. pumila

Degree of susceptibility of industrial gases of tree and shrub species

Energy Technology Data Exchange (ETDEWEB)

Dobrovoljskii, I A

1952-01-01

The trees and shrubs of the iron smelting region of Krivoi Rog, in the Ukraine, were surveyed to determine susceptibility to air pollution damage. Most of the observations were made in parks and green belts in industrial areas. A classification of tree and shrub species is presented; they are separated into three classes according to their susceptibility to air pollutant injury.

Does NDVI reflect variation in the structural attributes associated with increasing shrub dominance in arctic tundra?

Energy Technology Data Exchange (ETDEWEB)

Boelman, Natalie T [Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY 10964 (United States); Gough, Laura; McLaren, Jennie R [Department of Biology, University of Texas at Arlington, Arlington, TX 76019 (United States); Greaves, Heather, E-mail: nboelman@ldeo.columbia.edu [Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, OR 97331 (United States)

2011-07-15

This study explores relationships between the normalized difference vegetation index (NDVI) and structural characteristics associated with deciduous shrub dominance in arctic tundra. Our structural measures of shrub dominance are stature, branch abundance, aerial per cent woody stem cover (deciduous and evergreen species), and per cent deciduous shrub canopy cover. All measurements were taken across a suite of transects that together represent a gradient of deciduous shrub height. The transects include tussock tundra shrub and riparian shrub tundra communities located in the northern foothills of the Brooks Range, in northern Alaska. Plot-level NDVI measurements were made in 2010 during the snow-free period prior to deciduous shrub leaf-out (early June, NDVI{sub pre-leaf}), at the point in the growing season when canopy NDVI has reached half of its maximum growing season value (mid-June, NDVI{sub demi-leaf}) and during the period of maximum leaf-out (late July, NDVI{sub peak-leaf}). We found that: (1) NDVI{sub pre-leaf} is best suited to capturing variation in the per cent woody stem cover, maximum shrub height, and branch abundance, particularly between 10 and 50 cm height in the canopy; (2) NDVI{sub peak-leaf} is best suited to capturing variation in deciduous canopy cover; and (3) NDVI{sub demi-leaf} does not capture variability in any of our measures of shrub dominance. These findings suggest that in situ NDVI measurements made prior to deciduous canopy leaf-out could be used to identify small differences in maximum shrub height, woody stem cover, and branch abundance (particularly between 10 and 50 cm height in the canopy). Because shrubs are increasing in size and regional extent in several regions of the Arctic, investigation into spectrally based tools for monitoring these changes are worthwhile as they provide a first step towards development of remotely sensed techniques for quantifying associated changes in regional carbon cycling, albedo, radiative

Does NDVI reflect variation in the structural attributes associated with increasing shrub dominance in arctic tundra?

International Nuclear Information System (INIS)

Boelman, Natalie T; Gough, Laura; McLaren, Jennie R; Greaves, Heather

2011-01-01

This study explores relationships between the normalized difference vegetation index (NDVI) and structural characteristics associated with deciduous shrub dominance in arctic tundra. Our structural measures of shrub dominance are stature, branch abundance, aerial per cent woody stem cover (deciduous and evergreen species), and per cent deciduous shrub canopy cover. All measurements were taken across a suite of transects that together represent a gradient of deciduous shrub height. The transects include tussock tundra shrub and riparian shrub tundra communities located in the northern foothills of the Brooks Range, in northern Alaska. Plot-level NDVI measurements were made in 2010 during the snow-free period prior to deciduous shrub leaf-out (early June, NDVI pre-leaf ), at the point in the growing season when canopy NDVI has reached half of its maximum growing season value (mid-June, NDVI demi-leaf ) and during the period of maximum leaf-out (late July, NDVI peak-leaf ). We found that: (1) NDVI pre-leaf is best suited to capturing variation in the per cent woody stem cover, maximum shrub height, and branch abundance, particularly between 10 and 50 cm height in the canopy; (2) NDVI peak-leaf is best suited to capturing variation in deciduous canopy cover; and (3) NDVI demi-leaf does not capture variability in any of our measures of shrub dominance. These findings suggest that in situ NDVI measurements made prior to deciduous canopy leaf-out could be used to identify small differences in maximum shrub height, woody stem cover, and branch abundance (particularly between 10 and 50 cm height in the canopy). Because shrubs are increasing in size and regional extent in several regions of the Arctic, investigation into spectrally based tools for monitoring these changes are worthwhile as they provide a first step towards development of remotely sensed techniques for quantifying associated changes in regional carbon cycling, albedo, radiative energy balance, and wildlife

Food for early succession birds: relationships among arthropods, shrub vegetation, and soil

Science.gov (United States)

Richard N. Conner; Daniel Saenz; D. Brent Burt

2006-01-01

During spring and early summer, shrub- and herbaceous-level vegetation provides nesting and foraging habitat for many shrub-habitat birds. We examined relationships among arthropod biomass and abundance, foliage leaf surface area and weight, vegetation ground cover, soil characteristics, relative humidity, and temperature to evaluate what factors may influence...

Nitrogen cycling in summer active perennial grass systems in South Australia: Non-symbiotic nitrogen fixation

NARCIS (Netherlands)

Gupta, V.V.S.R.; Kroker, S.J.; Hicks, M.; Davoren, W.; Descheemaeker, K.K.E.; Llewellyn, R.

2014-01-01

Non-symbiotic nitrogen (N2) fixation by diazotrophic bacteria is a potential source for biological N inputs in non-leguminous crops and pastures. Perennial grasses generally add larger quantities of above- and belowground plant residues to soil, and so can support higher levels of soil biological

Disentangling the effects of shrubs and herbivores on tree regeneration in a dry Chaco forest (Argentina).

Science.gov (United States)

Tálamo, Andrés; Barchuk, Alicia H; Garibaldi, Lucas A; Trucco, Carlos E; Cardozo, Silvana; Mohr, Federico

2015-07-01

Successful persistence of dry forests depends on tree regeneration, which depends on a balance of complex biotic interactions. In particular, the relative importance and interactive effects of shrubs and herbivores on tree regeneration are unclear. In a manipulative study, we investigated if thornless shrubs have a direct net effect, an indirect positive effect mediated by livestock, and/or an indirect negative effect mediated by small vertebrates on tree regeneration of two key species of Chaco forest (Argentina). In a spatial association study, we also explored the existence of net positive interactions from thorny and thornless shrubs. The number of Schinopsis lorentzii seedlings was highest under artificial shade with native herbivores and livestock excluded. Even excluding livestock, no seedlings were found with natural conditions (native herbivores present with natural shade or direct sunlight) at the end of the experiment. Surprisingly, seedling recruitment was not enhanced under thornless shrubs, because there was a complementary positive effect of shade and interference. Moreover, thornless shrubs had neither positive nor negative effects on regeneration of S. lorentzii. Regeneration of Aspidosperma quebracho-blanco was minimal in all treatments. In agreement with the experiment, spatial distributions of saplings of both tree species were independent of thornless shrubs, but positively associated with thorny shrubs. Our results suggest that in general thornless shrubs may have a negligible effect and thorny shrubs a net positive effect on tree regeneration in dry forests. These findings provide a conceptual framework for testing the impact of biotic interactions on seedling recruitment in other dry forests.

Above- and Belowground Biomass Allocation in Shrub Biomes across the Northeast Tibetan Plateau

Science.gov (United States)

Yang, Yuanhe; Yang, Lucun; Zhou, Guoying

2016-01-01

Biomass partitioning has been explored across various biomes. However, the strategies of allocation in plants still remain contentious. This study investigated allocation patterns of above- and belowground biomass at the community level, using biomass survey from the Tibetan Plateau. We explored above- and belowground biomass by conducting three consecutive sampling campaigns across shrub biomes on the northeast Tibetan Plateau during 2011–2013. We then documented the above-ground biomass (AGB), below-ground biomass (BGB) and root: shoot ratio (R/S) and the relationships between R/S and environment factors using data from 201 plots surveyed from 67 sites. We further examined relationships between above-ground and below-ground biomass across various shrub types. Our results indicated that the median values of AGB, BGB, and R/S in Tibetan shrub were 1102.55, 874.91 g m-2, and 0.85, respectively. R/S showed significant trend with mean annual precipitation (MAP), while decreased with mean annual temperature (MAT). Reduced major axis analysis indicated that the slope of the log-log relationship between above- and belowground biomass revealed a significant difference from 1.0 over space, supporting the optimal hypothesis. Interestingly, the slopes of the allometric relationship between log AGB and log BGB differed significantly between alpine and desert shrub. Our findings supported the optimal theory of above- and belowground biomass partitioning in Tibetan shrub, while the isometric hypothesis for alpine shrub at the community level. PMID:27119379

Integration of vessel traits, wood density, and height in angiosperm shrubs and trees.

Science.gov (United States)

Martínez-Cabrera, Hugo I; Schenk, H Jochen; Cevallos-Ferriz, Sergio R S; Jones, Cynthia S

2011-05-01

Trees and shrubs tend to occupy different niches within and across ecosystems; therefore, traits related to their resource use and life history are expected to differ. Here we analyzed how growth form is related to variation in integration among vessel traits, wood density, and height. We also considered the ecological and evolutionary consequences of such differences. In a sample of 200 woody plant species (65 shrubs and 135 trees) from Argentina, Mexico, and the United States, standardized major axis (SMA) regression, correlation analyses, and ANOVA were used to determine whether relationships among traits differed between growth forms. The influence of phylogenetic relationships was examined with a phylogenetic ANOVA and phylogenetically independent contrasts (PICs). A principal component analysis was conducted to determine whether trees and shrubs occupy different portions of multivariate trait space. Wood density did not differ between shrubs and trees, but there were significant differences in vessel diameter, vessel density, theoretical conductivity, and as expected, height. In addition, relationships between vessel traits and wood density differed between growth forms. Trees showed coordination among vessel traits, wood density, and height, but in shrubs, wood density and vessel traits were independent. These results hold when phylogenetic relationships were considered. In the multivariate analyses, these differences translated as significantly different positions in multivariate trait space occupied by shrubs and trees. Differences in trait integration between growth forms suggest that evolution of growth form in some lineages might be associated with the degree of trait interrelation.

Effect of supplementation with barley and calcium hydroxide on intake of Mediterranean shrubs

Directory of Open Access Journals (Sweden)

Dragan Skobic

2011-04-01

Full Text Available Maquis plant communities are one of the most varied vegetation types in the Mediterranean region and an important habitat for wild and domestic herbivores. Although the majority of these shrubs are nutritious, the secondary compounds are main impediments that reduce their forage value. In five experiments we determined the effect of supplementing goats with calcium hydroxide plus barley, and barley alone on intake of five dominant shrubs (Quercus ilex, Erica multiflora, Arbutus unedo, Viburnum tinus and Pistacia lentiscus of the Mediterranean maquis community. The combination of calcium hydroxide plus barley and barley alone increased utilization of all five investigated Mediterranean shrubs; therewith that intake of Arbutus unedo and Viburnum tinus was not statistically significant. Supplemented goats with calcium hydroxide plus barley or barley alone could be effective in controlling secondary compounds-rich Mediterranean shrubs where their abundance threatens biodiversity. This control can be facilitated by browsing dominant Mediterranean shrubs, which has been shown to be effective in managing Mediterranean maquis density. Calcium hydroxide and barley (energy enhance use of secondary compounds-containing plants, which may increase production of alternate forages and create a more diverse mix of plant species in the Mediterranean maquis plant community.

Role of nurse shrubs for restoration planting of two conifers in southeast of Mu Us Sandland, China.

Science.gov (United States)

Tian, Li; Wang, Xiaoan

2015-01-01

Two-year-old pine seedlings, Pinus tabulaeformis and Pinus sylvestris were planted under the canopies of three shrub species and in open areas to test for facilitation during seedling establishment in southeast of Mu Us Sandland in northern part of Shaanxi, China. Pine seedlings establishment were assessed three times within three consecutive growing seasons. Height, area and volume of shrubs were measured. Microclimate conditions (light intensity, air temperature and soil temperature and moisture) were recorded in four microhabitats. Near surface light intensity, air temperature and soil temperature were lower under shrubs, which led to higher soil moisture and pine seedlings under the canopy of shrub species. Pine seedlings survival was remarkably higher when planted under the canopy of shrub species (65.7% for P. tabulaeformis and 60.6% for P. sylvestris) as compared with open areas (22.4% for P. tabulaeformis and 38% for P. sylvestris). P. tabulaeformis with shade-tolerance trait expressed high survival of seedlings as compared to that of P. sylvestris seedlings under the canopy of shrub species (Tukey test, P shrub (Caragana korshinskii and Amorpha fruticosa) showed continuously facilitation during moderate drought stress (summer 2012, 2013 and 2014), but dense and small shrub (Caragana korshinskii) reduced the establishment of seedlings possibly for light competition. Salix cheilophila showed a facilitation effect in growing seasons, but the effect of allelopathy led to high mortality of seedlings under their canopy. in addition, two pine growths were not inhibited when planted under three shrubs. In conclusions, nurse-shrub facilitation can be used as an effective restoration strategy in this sandland. However, use of shrubs as nurse plants depends on their canopy structure and ecological impacts; the selection of target species depends on their shade tolerance traits.

[Soil moisture dynamics of artificial Caragana microphylla shrubs at different topographical sites in Horqin sandy land].

Science.gov (United States)

Huang, Gang; Zhao, Xue-yong; Huang, Ying-xin; Su, Yan-gui

2009-03-01

Based on the investigation data of vegetation and soil moisture regime of Caragana microphylla shrubs widely distributed in Horqin sandy land, the spatiotemporal variations of soil moisture regime and soil water storage of artificial sand-fixing C. microphylla shrubs at different topographical sites in the sandy land were studied, and the evapotranspiration was measured by water balance method. The results showed that the soil moisture content of the shrubs was the highest in the lowland of dunes, followed by in the middle, and in the crest of the dunes, and increased with increasing depth. No water stress occurred during the growth season of the shrubs. Soil moisture content of the shrubs was highly related to precipitation event, and the relationship of soil moisture content with precipitation was higher in deep soil layer (50-180 cm) than in shallow soil layer (0-50 cm). The variation coefficient of soil moisture content was also higher in deep layer than in shallow layer. Soil water storage was increasing in the whole growth season of the shrubs, which meant that the accumulation of soil water occurred in this area. The evapotranspiriation of the shrubs occupied above 64% of the precipitation.

Breeding for Grass Seed Yield

DEFF Research Database (Denmark)

Boelt, Birte; Studer, Bruno

2010-01-01

Seed yield is a trait of major interest for many fodder and amenity grass species and has received increasing attention since seed multiplication is economically relevant for novel grass cultivars to compete in the commercial market. Although seed yield is a complex trait and affected...... by agricultural practices as well as environmental factors, traits related to seed production reveal considerable genetic variation, prerequisite for improvement by direct or indirect selection. This chapter first reports on the biological and physiological basics of the grass reproduction system, then highlights...... important aspects and components affecting the seed yield potential and the agronomic and environmental aspects affecting the utilization and realization of the seed yield potential. Finally, it discusses the potential of plant breeding to sustainably improve total seed yield in fodder and amenity grasses....

Resilience of arctic mycorrhizal fungal communities after wildfire facilitated by resprouting shrubs

Science.gov (United States)

Rebecca E. Hewitt; Elizabeth Bent; Teresa N. Hollingsworth; F. Stuart Chapin; D. Lee Taylor

2013-01-01

Climate-induced changes in the tundra fire regime are expected to alter shrub abundance and distribution across the Arctic. However, little is known about how fire may indirectly impact shrub performance by altering mycorrhizal symbionts. We used molecular tools, including ARISA and ITS sequencing, to characterize the mycorrhizal communities on resprouting ...

Trends and patterns of anthropogenic evolution of chernozems in lands of agricultural afforestation within the territory of forest-steppe in the center of eastern Europe

Science.gov (United States)

The anthropogenic evolution of chernozems as a result of plowing and the creation of forest shelterbelts on three meadow-steppe areas of forest-steppe were studied. It was established, that in all areas there are similar patterns, caused by the transformation of virgin soils into arable soils and vi...

Ethnobotanical survey of medicinal plants used by nomadic peoples in the Algerian steppe.

Science.gov (United States)

Miara, Mohamed Djamel; Bendif, Hamdi; Ait Hammou, Mohammed; Teixidor-Toneu, Irene

2018-06-12

This study is the first ethnobotanical survey focusing on the herbal medicines traditionally used by the nomadic community of the Algerian steppe, identifying new medicinal plants and uses from one of the most characteristic indigenous populations in Algeria. Moreover, the study contributes to the understanding of transmission of medicinal plant knowledge in the Mediterranean basin. This work aims to document the phytotherapeutical knowledge and practice of the nomadic community of the Algerian steppe, and compare it with neighbouring sedentary populations and Mediterranean historical texts. Through this, the study strives to evaluate processes of transmission of knowledge among this population, for whom written sources have been largely unavailable. Ethnobotanical surveys were carried out during two years (2015-2017). In total, 73 informants from nomadic populations were interviewed in several steppe regions including areas in the administrative departments of Tiaret, Saida, Naama, Djelfa and M'sila. Structured interviews about medicinal plant knowledge were combined with guided tours with the informants. Prior informed consent was always obtained. The surveys allowed for the collection of sociodemographic data and traditional knowledge about medicinal plants and their uses. Informant Consensus Factor (F IC ) was calculated to evaluate agreement among informants. Results were compared to existing literature to evaluate similarities between this nomadic medicinal flora, that of neighbouring communities and historical texts and identify new plant citations and uses. Among Algerian nomadic communities, herbal remedies are used mostly by women and elders, who are often illiterate. We identified 97 taxa of medicinal plants belonging to 42 botanical families, importantly Lamiaceae, Asteraceae and Apiaceae, like in neighbouring communities. The most common plant parts and method of preparation are also shared with neighbouring populations. New uses are described for 25

Chemicals from trees and shrubs

Energy Technology Data Exchange (ETDEWEB)

Halloran, G M

1978-01-01

The need for finding economically viable alternatives to crude oil is discussed in the context of Australia's uncertain reserves of black coal, from which crude oil derivatives may have to be obtained when oil supplies become depleted. A table is presented showing the major fractions of crude oil and the likely sources (in general terms) of equivalent substances from forest trees, shrubs and agricultural species.

Soil water availability and rooting depth as determinants of hydraulic architecture of Patagonian woody species

Science.gov (United States)

Sandra J. Bucci; Fabian G. Scholz; Guillermo Goldstein; Frederick C. Meinzer; Maria E. Arce

2009-01-01

We studied the water economy of nine woody species differing in rooting depth in a Patagonian shrub steppe from southern Argentina to understand how soil water availability and rooting depth determine their hydraulic architecture. Soil water content and potentials, leaf water potentials (Leaf) hydraulic conductivity, wood density (Pw), rooting depth, and specific leaf...

Post-ruminal digestibility of crude protein from grass and grass silages in cows

NARCIS (Netherlands)

Cone, J.W.; Gelder, van A.H.; Mathijssen-Kamman, A.A.; Hindle, V.A.

2006-01-01

Grass samples were grown on a clay or sandy soil, fertilised with 150 or 300 kg N/ha per year, and harvested on different days during two consecutive growing seasons. The grass samples were stored frozen or ensiled after wilting to approximately 250 or 450 g DM/kg. The recoveries of crude protein

Establishment of native and exotic grasses on mine overburden and topsoil in the Hunter Valley, New South Wales

Energy Technology Data Exchange (ETDEWEB)

Huxtable, C.H.A.; Koen, T.B.; Waterhouse, D. [DNR, Dangar, NSW (Australia)

2005-07-01

Current recommendations for rehabilitation of open-cut coal mines in the Hunter Valley involve the sowing of exotic pasture species to reinstate mined land to Class IV and V under the Rural Land Capability System. Despite the importance of native grasses in the pre-mined landscape, they are currently not widely included in mine rehabilitation. To address this issue a project was conducted between 1994 and 2000 to research the use of native grasses for rehabilitation of open-cut coal mines in the Hunter Valley. This paper reports on 2 mine site experiments that aimed to assess establishment and persistence of a broad range of native and exotic grass species from an autumn sowing in both topsoil and raw spoil over a period of 61 months. The most promising natives in terms of early establishment, persistence and spread over time, included six C-3 accessions (five Austrodanthonia spp. and Austrostipa bigeniculata) and one C-4 accession (Cynodon dactylon). Persistence of these accessions was better in raw spoil than topsoil, despite initial low numbers, due to a lack of weed competition and their ability to spread by self-seeding. In topsoil, and in the absence of any biomass reduction, native species were mostly out-competed by vigorous exotic perennial grasses which were sown in these experiments and from seed influx from adjacent rehabilitation areas or from the soil seed bank. The effects of climatic conditions and differences in soil physical, chemical and seed bank characteristics at the 2 mine sites are also discussed.

Trophic cascades: linking ungulates to shrub-dependent birds and butterflies.

Science.gov (United States)

J Teichman, Kristine; Nielsen, Scott E; Roland, Jens

2013-11-01

1. Studies demonstrating trophic cascades through the loss of top-down regulatory processes in productive and biologically diverse terrestrial ecosystems are limited. 2. Elk Island National Park, Alberta and surrounding protected areas have a wide range of ungulate density due to the functional loss of top predators, management for high ungulate numbers and variable hunting pressure. This provides an ideal setting for studying the effects of hyper-abundant ungulates on vegetation and shrub-dependent bird and butterfly species. 3. To examine the cascading effects of high ungulate density, we quantified vegetation characteristics and abundances of yellow warbler Dendroica petechia and Canadian tiger swallowtail Papilio canadensis under different ungulate density in and around Elk Island National Park. 4. Using Structural Equation Models we found that ungulate density was inversely related to shrub cover, whereas shrub cover was positively related to yellow warbler abundance. In addition, chokecherry Prunus virginiana abundance was inversely related to browse impact but positively related to P. canadensis abundance. 5. These results demonstrate a cascade resulting from hyper-abundant ungulates on yellow warblers and Canadian tiger swallowtails through reductions in shrub cover and larval host plant density. The combined effect of the functional loss of top predators and management strategies that maintain high ungulate numbers can decouple top-down regulation of productive temperate ecosystems. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

"Pleistocene Park" - A Glacial Ecosystem in a Warming World

Science.gov (United States)

Zimov, N.; Zimov, S. A.

2011-12-01

Most people if asked what association they have to the phrase - ice age, will answer - "Mammoth". But mammoths are not only big wooly elephants which went extinct in the beginning of Holocene. They were also part of a great ecosystem, the Northern Steppe or Mammoth Ecosystem, which was the world's largest ecosystem for hundreds thousand of years. This ecosystem, with extremely high rates of biocycling, could maintain animal densities which can be hardly found anywhere in the modern world. Northern steppe played an important role in shaping the glacial climate of the planet. High albedo grasslands reflected a much bigger portion of sun heat back to the atmosphere. Cold soils and permafrost served as sinks of carbon, helping to keep greenhouse gas concentration in the atmosphere at low levels. In the beginning of Holocene, simultaneously with wave of human expansion, an extinction wave took place. Tens of megafauna species became extinct at that time worldwide, while ones that resisted the extinction substantially dropped in numbers. The Northern Steppe ecosystem became imbalanced. Without large numbers of herbivores grazing and trampling the pasture, trees, shrubs and moss invaded grasslands. Within just a few hundreds years the mammoth ecosystem was gone, replaced by much lower productivity ecosystems. Already 14 thousand year ago, by simply increasing hunting pressure, humans managed to dramatically change Earth's appearance. We propose that by artificially maintaining a high animal density and diversity on a limited territory for extended period of time, it will be possible to reverse the shift, reestablishing the productive Northern Steppe ecosystem. Moss, shrubs and tree sprouts are not able to resist grazing pressure so they will be quickly replaced by grasses and herbs. Animals digesting all aboveground biomass would accelerate nutrition cycling and consequently increase bioproductivity. Higher bioproductivity would increase evapotranspiration, keeping soils

Changes in semi-arid plant species associations along a livestock grazing gradient.

Directory of Open Access Journals (Sweden)

Hugo Saiz

Full Text Available In semi-arid ecosystems, vegetation is heterogeneously distributed, with plant species often associating in patches. These associations between species are not constant, but depend on the particular response of each species to environmental factors. Here, we investigated how plant species associations change in response to livestock grazing in a semi-arid ecosystem, Cabo de Gata-Níjar Natural Park in South East Spain. We established linear point-intercept transects at four sites with different grazing intensity, and recorded all species at each point. We investigated plant associations by comparing the number of times that each pair of species occurred at the same spatial point (co-occurrences, with the expected number of times based on species abundances. We also assessed associations for each shrub and grass species by considering all their pairs of associations and for the whole plant community by considering all pairs of associations on each site. At all sites, the plant community had a negative pattern of association, with fewer co-occurrences than expected. Negative association in the plant community increased at maximum grazing intensity. Most species associated as expected, particularly grass species, and positive associations were most important at intermediate grazing intensities. No species changed its type of association along the grazing gradient. We conclude that in the present plant community, grazing-resistant species compete among themselves and segregate in space. Some shrub species act as refuges for grazing-sensitive species that benefit from being spatially associated with shrub species, particularly at intermediate grazing intensities where positive associations were highest. At high grazing intensity, these shrubs can no longer persist and positive associations decrease due to the disappearance of refuges. Spatial associations between plant species and their response to grazing help identify the factors that organize

Functional group, biomass, and climate change effects on ecological drought in semiarid grasslands

Science.gov (United States)

Wilson, Scott D.; Schlaepfer, Daniel R.; Bradford, John B.; Lauenroth, William K.; Duniway, Michael C.; Hall, Sonia A.; Jamiyansharav, Khishigbayar; Jia, Gensuo; Lkhagva, Ariuntsetseg; Munson, Seth M.; Pyke, David A.; Tietjen, Britta

2018-01-01

Water relations in plant communities are influenced both by contrasting functional groups (grasses, shrubs) and by climate change via complex effects on interception, uptake and transpiration. We modelled the effects of functional group replacement and biomass increase, both of which can be outcomes of invasion and vegetation management, and climate change on ecological drought (soil water potential below which photosynthesis stops) in 340 semiarid grassland sites over 30‐year periods. Relative to control vegetation (climate and site‐determined mixes of functional groups), the frequency and duration of drought were increased by shrubs and decreased by annual grasses. The rankings of shrubs, control vegetation, and annual grasses in terms of drought effects were generally consistent in current and future climates, suggesting that current differences among functional groups on drought effects predict future differences. Climate change accompanied by experimentally‐increased biomass (i.e. the effects of invasions that increase community biomass, or management that increases productivity through fertilization or respite from grazing) increased drought frequency and duration, and advanced drought onset. Our results suggest that the replacement of perennial temperate semiarid grasslands by shrubs, or increased biomass, can increase ecological drought both in current and future climates.

Fire cue effects on seed germination of six species of northwestern Patagonian grasslands

Science.gov (United States)

Gonzalez, S. L.; Ghermandi, L.

2012-09-01

Postfire recruitment of seedlings has been attributed to a stimulation of germination by fire-related cues. The germination response to heat shock (80 °C - 5 min), smoke (60 min), the combination of both factors and no heat no smoke (control) was studied in six native species (two dominant grasses, two dominant shrubs and two annual fugitive herbs) of northwestern Patagonian grasslands. Seeds of the grasses Festuca pallescens and Stipa speciosa and the shrub Senecio bracteolatus (Asteraceae) germinated when they were exposed to heat shock, whereas seeds of the other shrub, Mulinum spinosum (Apiaceae), were killed by this fire cue. In grasses, probably the glume of caryopsis protected embryos from heat. Possibly, the seed size could explain the different responses of the two shrubs. Heat combined with smoke reduced seed germination for S. speciosa and S. bracteolatus. The heat could have scarified seeds and the longer exposure to smoke could have been toxic for embryos. The same treatment increased germination of the annual fugitive herb Boopis gracilis (Calyceraceae). We concluded that fire differentially affects the seedling recruitment of the studied species in the northwestern Patagonian grasslands.

Indicators of ecosystem function identify alternate states in the sagebrush steppe.

Science.gov (United States)

Kachergis, Emily; Rocca, Monique E; Fernandez-Gimenez, Maria E

2011-10-01

Models of ecosystem change that incorporate nonlinear dynamics and thresholds, such as state-and-transition models (STMs), are increasingly popular tools for land management decision-making. However, few models are based on systematic collection and documentation of ecological data, and of these, most rely solely on structural indicators (species composition) to identify states and transitions. As STMs are adopted as an assessment framework throughout the United States, finding effective and efficient ways to create data-driven models that integrate ecosystem function and structure is vital. This study aims to (1) evaluate the utility of functional indicators (indicators of rangeland health, IRH) as proxies for more difficult ecosystem function measurements and (2) create a data-driven STM for the sagebrush steppe of Colorado, USA, that incorporates both ecosystem structure and function. We sampled soils, plant communities, and IRH at 41 plots with similar clayey soils but different site histories to identify potential states and infer the effects of management practices and disturbances on transitions. We found that many IRH were correlated with quantitative measures of functional indicators, suggesting that the IRH can be used to approximate ecosystem function. In addition to a reference state that functions as expected for this soil type, we identified four biotically and functionally distinct potential states, consistent with the theoretical concept of alternate states. Three potential states were related to management practices (chemical and mechanical shrub treatments and seeding history) while one was related only to ecosystem processes (erosion). IRH and potential states were also related to environmental variation (slope, soil texture), suggesting that there are environmental factors within areas with similar soils that affect ecosystem dynamics and should be noted within STMs. Our approach generated an objective, data-driven model of ecosystem dynamics

Chopping and webbing control saw-palmetto in south Florida

Science.gov (United States)

Clifford E. Lewis

1972-01-01

Saw-palmetto is one of the more troublesome plants growing in south Florida, and its control is often desirable in programs of range and timber management. Both cross-chopping and webbing (root plowing) proved to be effective control measures, but webbing appeared to be less effective on a moist site. Many other shrubs were also effectively reduced by these treatments...

[Rainfall and soil moisture redistribution induced by xerophytic shrubs in an arid desert ecosystem].

Science.gov (United States)

Wang, Zheng Ning; Wang, Xin Ping; Liu, Bo

2016-03-01

Rainfall partitioning by desert shrub canopy modifies the redistribution of incident rainfall under the canopy, and may affect the distribution pattern of soil moisture around the plant. This study examined the distribution of rainfall and the response of soil moisture beneath the canopy of two dominant desert shrubs, Caragana korshinskii and Artemisia ordosica, in the revegetation area at the southeastern edge of the Tengger Desert. The results showed that throughfall and stemflow ave-ragely occupied 74.4%, 11.3% and 61.8%, 5.5% of the gross precipitation for C. korshinskii and A. ordosica, respectively. The mean coefficients of variation (CV) of throughfall were 0.25 and 0.30, respectively. C. korshinski were more efficient than A. ordosica on stemflow generation. The depth of soil wetting front around the stem area was greater than other areas under shrub canopy for C. korshinski, and it was only significantly greater under bigger rain events for A. ordosica. The shrub canopy could cause the unevenness of soil wetting front under the canopy in consequence of rainfall redistribution induced by xerophytic shrub.

Variations in the Sensitivity of Shrub Growth to Climate Change along Arctic Environmental and Biotic Gradients

Science.gov (United States)

Beck, P. S. A.; Myers-Smith, I. H.; Elmendorf, S.; Georges, D.

2015-12-01

Despite evidence of rapid shrub expansion at many Arctic sites and the profound effects this has on ecosystem structure, biogeochemical cycling, and land-atmosphere feedbacks in the Arctic, the drivers of shrub growth remain poorly understood. The compilation of 41,576 annual shrub growth measurements made around the Arctic, allowed for the first systematic evaluation of the climate sensitivity of Arctic shrub growth, i.e. the strength of the relationship between annual shrub growth and monthly climate variables. The growth measurements were taken on 1821 plants of 25 species at 37 arctic and alpine sites, either as annual ring widths or as stem increments. We evaluated climate sensitivity of shrub growth for each genus-by-site combination in this data set based on the performance and parameters of linear mixed models that used CRU TS3.21 climate data as predictors of shrub growth between 1950 and 2010. 76% of genus-by-site combinations showed climate sensitive growth, but climate-growth relationships varied with soil moisture, species canopy height, and geographic position within the species ranges. Shrubs growing at sites with more soil moisture showed greater climate sensitivity, suggesting that water availability might limit shrub growth if continued warming isn't matched by a steady increase in soil moisture. Tall shrub species growing at their northern range limit were particularly climate sensitive causing climate sensitivity of shrubs to peak at the transition between Low and High Arctic, where carbon storage in permafrost is greatest. Local and regional studies have documented matching spatial and temporal patterns in dendrochronological measurements and satellite observations of vegetation indices both in boreal and Arctic regions. Yet the circumarctic comparison of patterns in dendrochronological and remote sensing data sets yielded poor levels of agreement. In much of the Arctic, steep environmental gradients generate fine spatial patterns of vegetation

Mapping the ecological dimensions and potential distributions of endangered relic shrubs in western Ordos biodiversity center.

Science.gov (United States)

Zhu, Geng-Ping; Li, Hui-Qi; Zhao, Li; Man, Liang; Liu, Qiang

2016-05-20

Potential distributions of endemic relic shrubs in western Ordos were poorly mapped, which hindered our implementation of proper conservation. Here we investigated the applicability of ecological niche modeling for endangered relic shrubs to detect areas of priority for biodiversity conservation and analyze differences in ecological niche spaces used by relic shrubs. We applied ordination and niche modeling techniques to assess main environmental drivers of five endemic relic shrubs in western Ordos, namely, Ammopiptanthus mongolicus, Amygdalus mongolica, Helianthemum songaricum, Potaninia mongolica, and Tetraena mongolica. We calculated niche overlap metrics in gridded environmental spaces and compared geographical projections of ecological niches to determine similarities and differences of niches occupied by relic shrubs. All studied taxa presented different responses to environmental factors, which resulted in a unique combination of niche conditions. Precipitation availability and soil quality characteristics play important roles in the distributions of most shrubs. Each relic shrub is constrained by a unique set of environmental conditions, the distribution of one species cannot be implied by the distribution of another, highlighting the inadequacy of one-fits-all type of conservation measure. Our stacked habitat suitability maps revealed regions around Yellow River, which are highly suitable for most species, thereby providing high conservation value.

Shrubs in the cold : interactions between vegetation, permafrost and climate in Siberian tundra

NARCIS (Netherlands)

Blok, D.

2011-01-01

The Arctic is experiencing strong increases in air temperature during the last decades. High-latitude tundra regions are very responsive to changes in temperature and may cause a shift in tundra vegetation composition towards greater dominance of deciduous shrubs. With increasing deciduous shrub

Grass pollen immunotherapy induces highly cross-reactive IgG antibodies to group V allergen from different grass species

NARCIS (Netherlands)

van Ree, R.; Brewczyński, P. Z.; Tan, K. Y.; Mulder-Willems, H. J.; Widjaja, P.; Stapel, S. O.; Aalberse, R. C.; Kroon, A. M.

1995-01-01

Sera from two groups of patients receiving grass pollen immunotherapy were tested on IgG reactivity with group V allergen from six different grass species. One group of patients was treated with a mixture of 10 grass species, and the other with a mixture of five. Only Lolium perenne, Dactylis

Hydrologic Vulnerability and Risk Assessment Associated With the Increased Role of Fire on Western Landscapes, Great Basin, USA

Science.gov (United States)

Williams, C. J.; Pierson, F. B.; Robichaud, P. R.; Spaeth, K. E.; Hardegree, S. P.; Clark, P. E.; Moffet, C. A.; Al-Hamdan, O. Z.; Boll, J.

2010-12-01

Landscape-scale plant community transitions and altered fire regimes across Great Basin, USA, rangelands have increased the likelihood of post-fire flooding and erosion events. These hazards are particularly concerning for western urban centers along the rangeland urban-wildland interface where natural resources, property, and human life are at risk. Extensive conversion of 4-7 million hectares of Great Basin shrub-steppe to cheatgrass-dominated (Bromus tectorum) grasslands has increased the frequency and size of wildland fires within these ecosystems. Fire frequencies have increased by more than an order of magnitude and occur on 3-10 year intervals across much of the cheatgrass-dominated landscape. Extensive tree (Pinus spp. and Juniperus spp.) encroachment into wooded shrub-steppe has increased heavy fuel loads. Ladder fuels in these ecosystems promote rapidly spreading, high-intensity and severe ground-surface-crown fires. These altered fuel structures across much of the historical Great Basin shrub-steppe have initiated an upsurge in large rangeland wildfires and have increased the spatial and temporal vulnerability of these landscapes to amplified runoff and erosion. Resource and infrastructure damages, and loss of life have been reported due to flooding following recent large-scale burning of western rangelands and dry forests. We present a decade of post-fire rangeland hydrologic research that provides a foundation for conceptual modeling of the hydrologic impacts associated with an increased role of rangeland wildfires. We highlight advancements in predictive tools to address this large-scale phenomenon and discuss vital research voids requiring attention. Our geographic emphasis is the Great Basin Region, however, these concepts likely extend elsewhere given the increased role of fire in many geographic regions and across rangeland-to-forest ecotones in the western United States.

The SMOS Mediterranean Ecosystem L-Band characterisation EXperiment (MELBEX-I) over natural shrubs

DEFF Research Database (Denmark)

Cano, Aurelio; Saleh, Kauzar; Wigneron, Jean-Pierre

2010-01-01

shrub land, as no data were available over this biome. For that purpose, multi-angular and dual polarimetric measurements (H, V) were obtained by the EMIRAD L-band radiometer from a 14-m tower. Results of this study indicate a small and constant impact of vegetation on the microwave emission of shrub...... land, and L-MEB parameters for shrub land were obtained. In addition, the study highlights the need for calibrating microwave soil roughness, which was found to be constant at the site. Depending on the number of retrieved parameters, soil moisture (SM) near the surface could be estimated with errors...

Atlas of United States Trees, Volume 2: Alaska Trees and Common Shrubs.

Science.gov (United States)

Viereck, Leslie A.; Little, Elbert L., Jr.

This volume is the second in a series of atlases describing the natural distribution or range of native tree species in the United States. The 82 species maps include 32 of trees in Alaska, 6 of shrubs rarely reaching tree size, and 44 more of common shrubs. More than 20 additional maps summarize environmental factors and furnish general…

Responses of nocturnal rodents to shrub encroachment in Banni grasslands, Gujarat, India

Science.gov (United States)

Jayadevan, A.

2016-12-01

Shrub encroachment is one of the greatest threats to grasslands globally. These woodlands can strongly influence the behaviour of small mammals adapted to more open habitats, which rely on high visibility for early detection of predators. In semi-arid grasslands, rodents are considered keystone species. Although shrub encroachment is known to negatively affect rodent assemblages, its impact on the foraging behaviour of rodents, which is known to vary in response to risky situations, is unknown. Understanding whether shrub encroachment alters such antipredator behaviour is important as antipredator behaviour can alter the distribution, abundance and ultimately, survival of prey species. In this study, I explored the effects of shrub encroachment on the foraging behaviour of nocturnal rodent communities in the Banni grasslands, India. I examined foraging behaviour, quantified using the giving-up density (GUD) framework and the number of rodent crossings around food patches, in two habitats that differed in the extent of shrub encroachment. Under the GUD framework, the amount of food left behind by a forager in a food patch reflects the costs of feeding at the patch. Higher GUDs imply higher foraging costs. I also investigated how removal of an invasive woody plant, Prosopis juliflora would affect foraging behaviour of nocturnal rodents. High shrub encroachment was associated with higher foraging costs (higher GUDs) and lower activity than the sparsely wooded habitat, likely due to low visibility in the densely wooded habitat. The dense habitat also supported a higher richness and relative abundance of generalist rodents than the sparse habitat, likely due to the increased heterogeneity of the habitat. The tree removal experiment revealed that rodents had lower GUDs (i.e., low foraging costs) after the event of tree cutting. This may be due to the reduction of cover in the habitat, leading to higher visibility and lower predation risk. My results suggest that shrub

Water and CO2 fluxes over semiarid alpine steppe and humid alpine meadow ecosystems on the Tibetan Plateau

Science.gov (United States)

Wang, Lei; Liu, Huizhi; Shao, Yaping; Liu, Yang; Sun, Jihua

2018-01-01

Based on eddy covariance flux data from July 15, 2014, to December 31, 2015, the water and CO2 fluxes were compared over a semiarid alpine steppe (Bange, Tibetan Plateau) and a humid alpine meadow (Lijiang, Yunnan) on the Tibetan Plateau and its surrounding region. During the wet season, the evaporative fraction (EF) was strongly and linearly correlated with the soil water content (SWC) at Bange because of its sparse green grass cover. In contrast, the correlation between the EF at Lijiang and the SWC and the normalized difference vegetation index (NDVI) was very low because the atmosphere was close to saturation and the EF was relatively constant. In the dry season, the EF at both sites decreased with the SWC. The net ecosystem exchange (NEE) at Bange was largely depressed at noon, while this phenomenon did not occur at Lijiang. The saturated NEE at Bange was 24% of that at Lijiang. The temperature sensitivity coefficient of ecosystem respiration at Bange (1.7) was also much lower than that at Lijiang (3.4). The annual total NEE in 2015 was 21.8 and -230.0 g C m-2 yr-1 at Bange and Lijiang, respectively, and the NEE was tightly controlled by the NDVI at the two sites. The distinct differences in the water and CO2 fluxes at Bange and Lijiang are attributed to the large SWC difference and its effect on vegetation growth.

Spatiotemporal Variation in the Environmental Controls of C4-Grass Origin and Ecology: Insights from Grass-Pollen δ13C Data

Science.gov (United States)

Nelson, D. M.; Urban, M.; Hu, F.

2014-12-01

Understanding the environmental factors controlling the origin and shifting abundance of C4 grasses in Earth's history is useful for projecting the response of C4-grass dominated grasslands to future environmental change. Unfortunately, grass pollen is typically morphologically indistinct, making palynological analysis a blunt tool for studying C4-grasses in the paleorecord. δ13C of individual grass-pollen grains using a spooling wire microcombustion device interfaced with an isotope ratio mass spectrometer (Single Pollen Isotope Ratio AnaLysis, SPIRAL) overcomes this challenge and the potential biases of δ13C data from other substrates (e.g. leaf waxes). To assess the presence and relative abundance of C3- and C4-grass pollen in samples of unknown composition, we developed a hierarchical Bayesian model, trained with ~1,900 δ13C values from pollen grains of 31 grass species. Surface-sediment data from Africa, Australia, and North America demonstrate the reliability of this technique for quantifying C4-grass abundance on the landscape. To investigate the timing and control of the origin of C4-grasses we analyzed samples from the Oligocene-Miocene from Europe and from the Eocene from North America. Results indicate that C4 grasses appeared on the landscape of southwest Europe no later than the early Oligocene, implying that low atmospheric pCO2 may not have been the main driver and/or precondition for the development of C4 photosynthesis in the grass family. In contrast, we found no evidence for C4 grasses in the southeast United States before pCO2 fell. In application of SPIRAL to the late Quaternary, we found that shifts in pCO2 and moisture balance exerted key controls on the relative abundance of C3 and C4 grasses in Africa and Australia. Overall, our results imply that as in the past, future changes in the C3/C4 composition of grass-dominated ecosystems will likely exhibit striking spatiotemporal variability as a result of differing combinations of

Guide de terrain des ligneux saheliens et soudano-guineens

NARCIS (Netherlands)

Geerling, C.

1983-01-01

This work is a field guide to the woody plants of the savannes and steppes of northern tropical Africa, from Senegal to Chad. 371 species of trees, shrubs and woody lianas, belonging to 62 families are included. The Dutch introduction comprises notes on fire, the use of the plants by Man, and the

Climate Compatible Development in the Mongolia Steppe: analysis of vulnerability and adaptation response to global changes

Science.gov (United States)

Ojima, D. S.; Togtokh, C.; Galvin, K. A.

2015-12-01

INTRODUCTION: Climate change and variability, market and policy changes are shaping pastoral communities' decisions on what pathways their future livelihoods will take and how the steppe landscapes and river basins, are managed. Recent droughts and damaging winter storms (zuds) of the past two decades have exacerbated the situation and undermined the natural capital on which the pastoral livelihoods depend upon. River basins are critical natural resources well-being of social-ecological systems in Mongolia. River basins provide the ecosystem services which support pastoral communities and industrial and urban development. Green development strategies are strongly dependent on water resources. Consequently, integrated planning of river basin management is needed to maintain these critical ecosystem services to meet the multiple needs of livelihoods of communities in these basins and to support sustainable development activities within the basins. For this study our team worked in nine sums (i.e., county level administrative areas) in three river basins in two provinces (aimags) to collect household data from 144 households. We also collected census data from the aimags and national level to understand trends at the level of ecosystems and river basins. We have selected 3 sums in each river basis, representing forest steppe, steppe and desert steppe regions for comparison across river basins and ecological zones. FINDINGS: Integrated planning efforts would be enhanced through, one, use of a social-ecological framework and, two, the development of a cross-ministerial working group to address natural resource considerations. Across the three basins agriculture, pastoral, industrial, and urban needs vie for similar ecosystem services. The natural capital and ecosystem services of these basins need to be assessed to understand the vulnerability and capacity of the resources. The most frequently listed "best coping strategy" across all ecosystem types was for herders to

The Kazakh Steppe at the Turn of the 18th-19th Centuries: Reforms and Projects

Directory of Open Access Journals (Sweden)

Vasilyev Dmitriy Valentinovich

2015-12-01

Full Text Available The following article is written on the basis of published and archival sources. O. Igelstrom’s reforms, and also the projects for government of the Kazakh Steppe prepared by some Russian officials, officers and ecclesiastics are considered by the author. Their singularities and differences are shown; the conclusion on their influence on the Russian policy in the region is drawn. The main attention is paid to reforms of O. Igelstrom who created the administrative institutions founded on local political tradition in the Small Horde. He intended to use them as instruments for the Russian influence in the Kazakh steppe. Local patrimonial leaders turned into government officials. But this experience was unsuccessful. Traditional Kazakh institutions didn’t conform to requirements of the Russian administration. The failure of those reforms provoked search of new models for the organization of Kazakh steppe’s administration. The Orenburg official D. Grankin suggested to refuse patrimonial division of the Small horde and to divide it according to the territorial principle. He suggested to include Russian officials and mullahs in all administrative bodies and to strengthen them by military detachments. The chief of the Siberian Lines Ya. Bouver suggested introducing the territorial division in the Middle Horde close to the imperial one. Expansion of the Russian sociocultural codes to the region was the main idea of his project. In the article considerable attention is paid to proposals of the Orenburg mufti M. Khusainov. He suggested to divide the Small Horde into two parts taking into account the patrimonial principle. The khan with sultans and advisers had to be at the head of each part. The deputies elected by notable Kazakhs had to become a sort of representative body in the part. The group of the armed Russian Muslims had to support safety in the Steppe. The Russian participation in internal administration of the Steppe was offered to minimize

Shrub type dominates the vertical distribution of leaf C : N : P stoichiometry across an extensive altitudinal gradient

Science.gov (United States)

Zhao, Wenqiang; Reich, Peter B.; Yu, Qiannan; Zhao, Ning; Yin, Chunying; Zhao, Chunzhang; Li, Dandan; Hu, Jun; Li, Ting; Yin, Huajun; Liu, Qing

2018-04-01

Understanding leaf stoichiometric patterns is crucial for improving predictions of plant responses to environmental changes. Leaf stoichiometry of terrestrial ecosystems has been widely investigated along latitudinal and longitudinal gradients. However, very little is known about the vertical distribution of leaf C : N : P and the relative effects of environmental parameters, especially for shrubs. Here, we analyzed the shrub leaf C, N and P patterns in 125 mountainous sites over an extensive altitudinal gradient (523-4685 m) on the Tibetan Plateau. Results showed that the shrub leaf C and C : N were 7.3-47.5 % higher than those of other regional and global flora, whereas the leaf N and N : P were 10.2-75.8 % lower. Leaf C increased with rising altitude and decreasing temperature, supporting the physiological acclimation mechanism that high leaf C (e.g., alpine or evergreen shrub) could balance the cell osmotic pressure and resist freezing. The largest leaf N and high leaf P occurred in valley region (altitude 1500 m), likely due to the large nutrient leaching from higher elevations, faster litter decomposition and nutrient resorption ability of deciduous broadleaf shrub. Leaf N : P ratio further indicated increasing N limitation at higher altitudes. Interestingly, drought severity was the only climatic factor positively correlated with leaf N and P, which was more appropriate for evaluating the impact of water status than precipitation. Among the shrub ecosystem and functional types (alpine, subalpine, montane, valley, evergreen, deciduous, broadleaf, and conifer), their leaf element contents and responses to environments were remarkably different. Shrub type was the largest contributor to the total variations in leaf stoichiometry, while climate indirectly affected the leaf C : N : P via its interactive effects on shrub type or soil. Collectively, the large heterogeneity in shrub type was the most important factor explaining the overall leaf C : N : P variations

ISOTOPES, PLANTS, AND RESERVOIR EFFECTS : CASE STUDY FROM THE CASPIAN STEPPE BRONZE AGE

NARCIS (Netherlands)

Shishlina, N.; Zazovskaya, E.; van der Plicht, J.; Sevastyanov, V.; Boaretto, E.; Rebollo Franco, N.R.

2012-01-01

Bronze Age human and animal bone collagen from several steppe Bronze Age cultures (i.e. Early Catacomb, East and West Manych Catacomb, and Lola cultures) shows large variations in delta C-13 and delta N-15 values. In general, we observed that the older the sample, the lower the delta C-13 and delta

Electrostatic Interactions between Elongated Monomers Drive Filamentation of Drosophila Shrub, a Metazoan ESCRT-III Protein

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Brian J. McMillan

2016-08-01

Full Text Available The endosomal sorting complex required for transport (ESCRT is a conserved protein complex that facilitates budding and fission of membranes. It executes a key step in many cellular events, including cytokinesis and multi-vesicular body formation. The ESCRT-III protein Shrub in flies, or its homologs in yeast (Snf7 or humans (CHMP4B, is a critical polymerizing component of ESCRT-III needed to effect membrane fission. We report the structural basis for polymerization of Shrub and define a minimal region required for filament formation. The X-ray structure of the Shrub core shows that individual monomers in the lattice interact in a staggered arrangement using complementary electrostatic surfaces. Mutations that disrupt interface salt bridges interfere with Shrub polymerization and function. Despite substantial sequence divergence and differences in packing interactions, the arrangement of Shrub subunits in the polymer resembles that of Snf7 and other family homologs, suggesting that this intermolecular packing mechanism is shared among ESCRT-III proteins.

Grass leaves as potential hominin dietary resources.

Science.gov (United States)

Paine, Oliver C C; Koppa, Abigale; Henry, Amanda G; Leichliter, Jennifer N; Codron, Daryl; Codron, Jacqueline; Lambert, Joanna E; Sponheimer, Matt

2018-04-01

Discussions about early hominin diets have generally excluded grass leaves as a staple food resource, despite their ubiquity in most early hominin habitats. In particular, stable carbon isotope studies have shown a prevalent C 4 component in the diets of most taxa, and grass leaves are the single most abundant C 4 resource in African savannas. Grass leaves are typically portrayed as having little nutritional value (e.g., low in protein and high in fiber) for hominins lacking specialized digestive systems. It has also been argued that they present mechanical challenges (i.e., high toughness) for hominins with bunodont dentition. Here, we compare the nutritional and mechanical properties of grass leaves with the plants growing alongside them in African savanna habitats. We also compare grass leaves to the leaves consumed by other hominoids and demonstrate that many, though by no means all, compare favorably with the nutritional and mechanical properties of known primate foods. Our data reveal that grass leaves exhibit tremendous variation and suggest that future reconstructions of hominin dietary ecology take a more nuanced approach when considering grass leaves as a potential hominin dietary resource. Copyright © 2017. Published by Elsevier Ltd.

Soil microbial diversity in the vicinity of desert shrubs.

Science.gov (United States)

Saul-Tcherkas, Vered; Unc, Adrian; Steinberger, Yosef

2013-04-01

Water and nutrient availability are the major limiting factors of biological activity in arid and semiarid ecosystems. Therefore, perennial plants have developed different ecophysiological adaptations to cope with harsh conditions. The chemical profile of the root exudates varies among plant species and this can induce variability in associated microbial populations. We examined the influence of two shrubs species, Artemisia sieberi and Noaea mucronata, on soil microbial diversity. Soil samples were collected monthly, from December 2006 to November 2007, near canopies of both shrubs (0-10-cm depth). Samples were used for abiotic tests and determination of soil bacterial diversity. No significant differences were found in the abiotic variables (soil moisture, total organic matter, and total soluble nitrogen (TSN)) between soil samples collected from under the two shrubs during the study period. No obvious differences in the Shannon-Weaver index, evenness values, or total phylogenetic distances were found for the soil microbial communities. However, detailed denaturing gradient gel electrophoresis (DGGE) clustering as well as taxonomic diversity analyses indicated clear shifts in the soil microbial community composition. These shifts were governed by seasonal variability in water availability and, significantly, by plant species type.

Analysis of Chinook Salmon in the Columbia River from an Ecosystem Perspective. Final Report.

Energy Technology Data Exchange (ETDEWEB)

Lichatowich, James A.; Mobrand, Lars E.

1995-01-01

Ecosystem Diagnosis and Treatment (EDT) methodology was applied to the analysis of chinook salmon in the mid-Columbia subbasins which flow through the steppe and steppe-shrub vegetation zones. The EDT examines historical changes in life history diversity related to changes in habitat. The emphasis on life history, habitat and historical context is consistent with and ecosystem perspective. This study is based on the working hypothesis that the decline in chinook salmon was at least in part due to a loss of biodiversity defined as the intrapopulation life history diversity. The mid Columbia subbasins included in the study are the Deschutes, John Day, Umatilla, Tucannon and Yakima.

The response of Arctic vegetation to the summer climate: relation between shrub cover, NDVI, surface albedo and temperature

Energy Technology Data Exchange (ETDEWEB)

Blok, Daan; Heijmans, Monique M P D; Berendse, Frank [Nature Conservation and Plant Ecology Group, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Schaepman-Strub, Gabriela [Institute of Evolutionary Biology and Environmental Studies, University of Zuerich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland); Bartholomeus, Harm [Centre for Geo-Information, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Maximov, Trofim C, E-mail: daan.blok@wur.nl [Biological Problems of the Cryolithozone, Russian Academy of Sciences, Siberian Division, 41, Lenin Prospekt, Yakutsk, The Republic of Sakha, Yakutia 677980 (Russian Federation)

2011-07-15

Recently observed Arctic greening trends from normalized difference vegetation index (NDVI) data suggest that shrub growth is increasing in response to increasing summer temperature. An increase in shrub cover is expected to decrease summer albedo and thus positively feed back to climate warming. However, it is unknown how albedo and NDVI are affected by shrub cover and inter-annual variations in the summer climate. Here, we examine the relationship between deciduous shrub fractional cover, NDVI and albedo using field data collected at a tundra site in NE Siberia. Field data showed that NDVI increased and albedo decreased with increasing deciduous shrub cover. We then selected four Arctic tundra study areas and compiled annual growing season maximum NDVI and minimum albedo maps from MODIS satellite data (2000-10) and related these satellite products to tundra vegetation types (shrub, graminoid, barren and wetland tundra) and regional summer temperature. We observed that maximum NDVI was greatest in shrub tundra and that inter-annual variation was negatively related to summer minimum albedo but showed no consistent relationship with summer temperature. Shrub tundra showed higher albedo than wetland and barren tundra in all four study areas. These results suggest that a northwards shift of shrub tundra might not lead to a decrease in summer minimum albedo during the snow-free season when replacing wetland tundra. A fully integrative study is however needed to link results from satellite data with in situ observations across the Arctic to test the effect of increasing shrub cover on summer albedo in different tundra vegetation types.

Why Be a Shrub? A Basic Model and Hypotheses for the Adaptive Values of a Common Growth Form

Science.gov (United States)

Götmark, Frank; Götmark, Elin; Jensen, Anna M.

2016-01-01

Shrubs are multi-stemmed short woody plants, more widespread than trees, important in many ecosystems, neglected in ecology compared to herbs and trees, but currently in focus due to their global expansion. We present a novel model based on scaling relationships and four hypotheses to explain the adaptive significance of shrubs, including a review of the literature with a test of one hypothesis. Our model describes advantages for a small shrub compared to a small tree with the same above-ground woody volume, based on larger cross-sectional stem area, larger area of photosynthetic tissue in bark and stem, larger vascular cambium area, larger epidermis (bark) area, and larger area for sprouting, and faster production of twigs and canopy. These components form our Hypothesis 1 that predicts higher growth rate for a small shrub than a small tree. This prediction was supported by available relevant empirical studies (14 publications). Further, a shrub will produce seeds faster than a tree (Hypothesis 2), multiple stems in shrubs insure future survival and growth if one or more stems die (Hypothesis 3), and three structural traits of short shrub stems improve survival compared to tall tree stems (Hypothesis 4)—all hypotheses have some empirical support. Multi-stemmed trees may be distinguished from shrubs by more upright stems, reducing bending moment. Improved understanding of shrubs can clarify their recent expansion on savannas, grasslands, and alpine heaths. More experiments and other empirical studies, followed by more elaborate models, are needed to understand why the shrub growth form is successful in many habitats. PMID:27507981

The response of Arctic vegetation to the summer climate: relation between shrub cover, NDVI, surface albedo and temperature

International Nuclear Information System (INIS)

Blok, Daan; Heijmans, Monique M P D; Berendse, Frank; Schaepman-Strub, Gabriela; Bartholomeus, Harm; Maximov, Trofim C

2011-01-01

Recently observed Arctic greening trends from normalized difference vegetation index (NDVI) data suggest that shrub growth is increasing in response to increasing summer temperature. An increase in shrub cover is expected to decrease summer albedo and thus positively feed back to climate warming. However, it is unknown how albedo and NDVI are affected by shrub cover and inter-annual variations in the summer climate. Here, we examine the relationship between deciduous shrub fractional cover, NDVI and albedo using field data collected at a tundra site in NE Siberia. Field data showed that NDVI increased and albedo decreased with increasing deciduous shrub cover. We then selected four Arctic tundra study areas and compiled annual growing season maximum NDVI and minimum albedo maps from MODIS satellite data (2000-10) and related these satellite products to tundra vegetation types (shrub, graminoid, barren and wetland tundra) and regional summer temperature. We observed that maximum NDVI was greatest in shrub tundra and that inter-annual variation was negatively related to summer minimum albedo but showed no consistent relationship with summer temperature. Shrub tundra showed higher albedo than wetland and barren tundra in all four study areas. These results suggest that a northwards shift of shrub tundra might not lead to a decrease in summer minimum albedo during the snow-free season when replacing wetland tundra. A fully integrative study is however needed to link results from satellite data with in situ observations across the Arctic to test the effect of increasing shrub cover on summer albedo in different tundra vegetation types.

Watch Out for Your Neighbor: Climbing onto Shrubs Is Related to Risk of Cannibalism in the Scorpion Buthus cf. occitanus.

Science.gov (United States)

Sánchez-Piñero, Francisco; Urbano-Tenorio, Fernando

The distribution and behavior of foraging animals usually imply a balance between resource availability and predation risk. In some predators such as scorpions, cannibalism constitutes an important mortality factor determining their ecology and behavior. Climbing on vegetation by scorpions has been related both to prey availability and to predation (cannibalism) risk. We tested different hypotheses proposed to explain climbing on vegetation by scorpions. We analyzed shrub climbing in Buthus cf. occitanus with regard to the following: a) better suitability of prey size for scorpions foraging on shrubs than on the ground, b) selection of shrub species with higher prey load, c) seasonal variations in prey availability on shrubs, and d) whether or not cannibalism risk on the ground increases the frequency of shrub climbing. Prey availability on shrubs was compared by estimating prey abundance in sticky traps placed in shrubs. A prey sample from shrubs was measured to compare prey size. Scorpions were sampled in six plots (50 m x 10 m) to estimate the proportion of individuals climbing on shrubs. Size difference and distance between individuals and their closest scorpion neighbor were measured to assess cannibalism risk. The results showed that mean prey size was two-fold larger on the ground. Selection of particular shrub species was not related to prey availability. Seasonal variations in the number of scorpions on shrubs were related to the number of active scorpions, but not with fluctuations in prey availability. Size differences between a scorpion and its nearest neighbor were positively related with a higher probability for a scorpion to climb onto a shrub when at a disadvantage, but distance was not significantly related. These results do not support hypotheses explaining shrub climbing based on resource availability. By contrast, our results provide evidence that shrub climbing is related to cannibalism risk.

Livestock forage and mineral relations on a shrub-steppe rangeland in northwestern United States of America

International Nuclear Information System (INIS)

Uresk, D.W.; Rickard, W.H.

1976-01-01

The study area is the Arid Lands Ecology (ALE) Reserve, a portion of the United States Energy Research and Development Administration's Hanford Reservation located in the semi-arid region of south-central Washington. Small experimental pastures were subjected to four consecutive years of moderate spring grazing by yearling steers. These pastures are unique in that they represent grazing stresses imposed upon previously ungrazed (by livestock) plant communities. These communities had been protected from grazing by livestock for more than 30 years under ERDA management. Bluebunch wheatgrass (Agropyron spicatum), the dominant species, was the major forage plant in the diet of the steers during the 1974 grazing season, followed by Cusick's bluegrass (Poa cusickii), Thurber's needlegrass (Stipa thurberiania) and hawksbeard (Crepis atrabarba). These four species made up approximately 93% of the total diet. The forage intake ranged from 9.9 kg/head daily to 10.9 kg/head daily during the grazing season. During this period, these steers gained a total of 21.6 kg/ha live weight. Fifteen kg of forage consumed produces 1 kg of live steer for a 6.7% conversion. The conversion rate for crude protein was 12.7%, 83.3% for phosphorus and 25.6% for calcium. (author)

Spatial, road geometric, and biotic factors associated with Barn Owl mortality along an interstate highway

Science.gov (United States)

Arnold, Erin M.; Hanser, Steven E.; Regan, Tempe; Thompson, Jeremy; Lowe, Melinda; Kociolek, Angela; Belthoff, James R.

2018-01-01

Highway programs typically focus on reducing vehicle collisions with large mammals because of economic or safety reasons while overlooking the millions of birds that die annually from traffic. We studied wildlife‐vehicle collisions along an interstate highway in southern Idaho, USA, with among the highest reported rates of American Barn Owl Tyto furcata road mortality. Carcass data from systematic and ad hoc surveys conducted in 2004–2006 and 2013–2015 were used to explore the extent to which spatial, road geometric, and biotic factors explained Barn Owl‐vehicle collisions. Barn Owls outnumbered all other identified vertebrate species of roadkill and represented > 25% of individuals and 73.6% of road‐killed birds. At a 1‐km highway segment scale, the number of dead Barn Owls decreased with increasing numbers of human structures, cumulative length of secondary roads near the highway, and width of the highway median. Number of dead Barn Owls increased with higher commercial average annual daily traffic (CAADT), small mammal abundance index, and with grass rather than shrubs in the roadside verge. The small mammal abundance index was also greater in roadsides with grass versus mixed shrubs, suggesting that Barn Owls may be attracted to grassy portions of the highway with more abundant small mammals for hunting prey. When assessed at a 3‐km highway segment scale, the number of dead Barn Owls again increased with higher CAADT as well as with greater numbers of dairy farms. At a 5‐km scale, number of dead Barn Owls increased with greater percentage of cropland near the highway. While human conversion of the environment from natural shrub‐steppe to irrigated agriculture in this region of Idaho has likely enhanced habitat for Barns Owls, it simultaneously has increased risk for owl‐vehicle collisions where an interstate highway traverses the altered landscape. We review some approaches for highway mitigation and suggest that reducing wildlife�

An African grassland responds similarly to long-term fertilization to the Park Grass experiment.

Directory of Open Access Journals (Sweden)

David Ward

Full Text Available We compared the results of a long-term (65 years experiment in a South African grassland with the world's longest-running ecological experiment, the Park Grass study at Rothamsted, U.K. The climate is warm and humid in South Africa and cool and temperate in England. The African grassland has been fertilized with two forms of nitrogen applied at four levels, phosphorus and lime in a crossed design in 96 plots. In 1951, about 84% of plant cover consisted of Themeda triandra, Tristachya leucothrix and Setaria nigrirostris. Currently, the dominant species are Panicum maximum, Setaria sphacelata and Eragrostis curvula, making up 71% of total biomass. As in the Park Grass experiment, we found a significant (additive interaction effect on ANPP of nitrogen and phosphorus, and a (marginally significant negative correlation between ANPP and species richness. Unlike the Park Grass experiment, there was no correlation between ANPP and species richness when pH was included as a covariate. There was also a significant negative effect of nitrogen amount and nitrogen form and a positive effect of lime on species richness and species diversity. Soil pH had an important effect on species richness. Liming was insufficient to balance the negative effects on species richness of nitrogen fertilization. There was a significant effect of pH on biomass of three abundant species. There were also significant effects of light on the biomass of four species, with only Panicum maximum having a negative response to light. In all of the abundant species, adding total species richness and ANPP to the model increased the amount of variance explained. The biomass of Eragrostis curvula and P. maximum were negatively correlated with species richness while three other abundant species increased with species richness, suggesting that competition and facilitation were active. Consistent with the results from the Park Grass and other long-term fertilization experiments of grasslands

Recent expansion of erect shrubs in the Low Arctic: evidence from Eastern Nunavik

International Nuclear Information System (INIS)

Tremblay, Benoît; Lévesque, Esther; Boudreau, Stéphane

2012-01-01

In order to characterize shrub response near the treeline in Eastern Nunavik (Québec), a region under extensive warming since the 1990s, we compared two series (1964 and 2003) of vertical aerial photos from the vicinity of Kangiqsualujjuaq. Our study revealed a widespread increase in erect woody vegetation cover. During the 40 years spanning the two photo series, erect shrub and tree cover increased markedly on more than half of the land surface available for new colonization or infilling. Within the 7.2 km 2 analysed, areas with dense shrub and tree cover (>90%) increased from 34% to 44% whereas areas with low cover (<10%) shrank from 45% to 29%. This increase in cover of trees and shrubs occurred throughout the landscape regardless of altitude, slope angle and exposure, although to varying extents. The main shrub species involved in this increase was Betula glandulosa Michx. (dwarf birch), which was present in 98% and dominant in 85% of the 345 plots. In addition, numerous seedlings and saplings of Larix laricina (Du Roi) K Koch (eastern larch) were found above the treeline (25% of the plots), suggesting that the altitudinal treeline might shift upslope in the near future. Sites that remained devoid of erect woody vegetation in 2003 were either characterized by the absence of a suitable seedbed or by harsh local microclimatic conditions (wind exposure or excessive drainage). Our results indicate dramatic increases in shrub and tree cover at a Low Arctic site in Eastern Nunavik, contributing to a growing number of observations of woody vegetation change from various areas around the North. (letter)

EFFECT OF MULCH AND MIXED CROPPING GRASS - LEGUME AT SALINE SOIL ON GROWTH, FORAGE YIELD AND NUTRITIONAL QUALITY OF GUINEA GRASS

Directory of Open Access Journals (Sweden)

F. Kusmiyati

2014-10-01

Full Text Available The research was conducted to evaluate the effect of mulch and mixed cropping grass – legume atsaline soil on growth, forage yield and nutritional quality of guinea grass. Saline soil used in thisresearch was classified into strongly saline soil with low soil fertility. The research was arrranged inrandomized complete block design with 3 blocks. The treatments were : M1 = guinea grassmonoculture, without mulch; M2 = guinea grass monoculture, 3 ton/ha mulch; M3 = guinea grassmonoculture, 6 ton/ha mulch, M4 = mixed cropping grass with Sesbania grandiflora, without mulch;M5 = mixed cropping grass with Sesbania grandiflora, 3 ton/ha mulch; M6 = mixed cropping grass withSesbania grandiflora, 6 ton/ha mulch. Data were analyzed using analysis of variance, then followed byDuncan's Multiple Range Test. The highest soil moisture content was achieved at mixed cropping grasslegumewith 6 ton/ha of mulch. The effect of mulch at saline soil significantly increased plant growth,forage yield and nutritional quality of guinea grass. Application of 3 ton/ha mulch increased plantgrowth, forage yield and nutritional quality of guinea grass. Plant growth, forage yield and nutritionalquality of guinea grass were not affected by monoculture or mixed cropping with Sesbania at saline soil.

Transfer of {sup 238}U, {sup 230}Th, {sup 226}Ra, and {sup 210}Pb from soils to tree and shrub species in a Mediterranean area

Energy Technology Data Exchange (ETDEWEB)

Blanco Rodriguez, P. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain); Vera Tome, F. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain)], E-mail: fvt@unex.es; Lozano, J.C. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain); Laboratorio de Radiaciones Ionizantes, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca (Spain); Perez Fernandez, M.A. [Natural Radioactivity Group, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, 06071 Badajoz (Spain); Area de Ecologia, Universidad Pablo Olavide, Carretera de Utrera km. 1, 41013 Sevilla (Spain)

2010-06-15

The soil-to-plant transfer factors of natural uranium isotopes ({sup 238}U and {sup 234}U), {sup 230}Th, {sup 226}Ra, and {sup 210}Pb were studied in a disused uranium mine located in the Extremadura region in the south-west of Spain. The plant samples included trees (Quercus ilex, Quercus suber, and Eucalyptus cameldulensis) and one shrub (Cytisus multiflorus). All of them are characteristic of Mediterranean environments. The activity concentrations in leaves and fruit were determined for the tree species at different stages of growth. For the shrub, the total above-ground fraction was considered in three seasons. For old leaves and fruit, the highest activity concentrations were found in Eucalyptus cameldulensis for all the radionuclides studied, except in the case of {sup 230}Th that presented similar activity concentrations in all of the tree species studied. In every case, the transfer to fruit was less than the transfer to leaves. In the shrub, the results depended on the season of sampling, with the highest value obtained in spring and the lowest in autumn. Important correlations were obtained for {sup 238}U and {sup 226}Ra between the activity ratio in soils with that in leaves or fruit.

Effects of vegetation on runoff generation, sediment yield and soil shear strength on road-side slopes under a simulation rainfall test in the Three Gorges Reservoir Area, China.

Science.gov (United States)

Liu, Yao-Jun; Wang, Tian-Wei; Cai, Chong-Fa; Li, Zhao-Xia; Cheng, Dong-Bing

2014-07-01

Vegetation recolonization has often been used to control roadside slope erosion, and in this paper, four restoration models - Natural Restoration, Grass, Grass & Shrub, Sodded Strip - were chosen to recolonize the plants on a newly built unpaved roadside slope in the Three Gorges Reservoir Area. After eight months growth, eight rainfall simulations (intensity of 90 mm h(-1) for 60 min) and in-situ soil shear strength test were then carried out to identify the impacts of vegetation on roadside slope erosion and soil shear strength. The erosion on cutslopes was higher than that on fillslopes. The runoff coefficient and soil detachment rate were significantly lower on the Grass & Shrub model (4.3% and 1.99 g m(-2) min(-1), respectively) compared with the other three, which had the highest surface cover (91.4%), aboveground biomass (1.44 kg m(-2)) and root weight density (3.94 kg m(-3)). The runoff coefficient and soil detachment rate on roadside slopes showed a logarithmic decrease with the root weight density, root length density and aboveground biomass. The soil shear strength measured before and after the rainfall was higher on Grass & Shrub (59.29 and 53.73 kPa) and decreased on Grass (46.93 and 40.48 kPa), Sodded Strip (31.20 and 18.87 kPa) and Natural Restoration (25.31 and 9.36 kPa). Negative linear correlations were found between the soil shear strength reduction and aboveground biomass, root weight density and root length density. The variation of soil shear strength reduction was closely related to the roadside slope erosion, a positive linear correlation was found between runoff coefficient and soil shear strength reduction, and a power function was shown between soil detachment rate and soil shear strength reduction. This study demonstrated that Grass and Grass & Shrub were more suitable and highly cost-effective in controlling initial period erosion of newly built low-volume unpaved road. Copyright © 2014 Elsevier B.V. All rights reserved.

Purpose of Introduction as a Predictor of Invasiveness among Introduced Shrubs in Rwanda

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Jean Leonard Seburanga

2015-01-01

Full Text Available The introduced shrub flora in Rwanda was analyzed and the risk of invasion was assessed based on the species’ purposes of introduction. The results showed that more than half of invasive alien shrubs in Rwanda were introduced as ornamentals. They include Agave americana L., Bryophyllum proliferum Bowie ex Hook., Caesalpinia decapetala (Roth Alston, Lantana camara L., and Tithonia diversifolia (Hemsley A. Gray. However, these represented only 3.16% of the total number of introduced ornamental shrubs. At the time when the study was conducted, no introduced food crop had become invasive. Species introduced for purposes other than food or culinary use showed higher likelihood of becoming invasive.

Evaluating grasses as a long-term energy resource

Energy Technology Data Exchange (ETDEWEB)

Christian, D.G.; Riche, A.B.

2001-07-01

The work reported here is part of an ongoing project that aims to evaluate the yields of three perennial rhizomatous grasses and determine their suitability as bio-energy crops. The work began in 1993, and the grasses have been monitored continuously since that time. This report covers the period 1999/2000, and includes: the performance of plots of the energy grasses Miscanthus grass, switchgrass and reed canary grass seven years after they were planted; assessment of the yield of 15 genotypes of Miscanthus planted in 1997; monitoring all the species throughout the growing period for the presence of pests, weeds and diseases; measurement of the amount of nitrate leached from below Miscanthus grass; investigating the occurrence of lodging in switchgrass. (Author)

Long-term stabilization of uranium mill tailings: effects of rock material on vegetation on soil moisture

International Nuclear Information System (INIS)

Beedlow, P.A.; Carlile, D.W.

1982-11-01

A field-scale experiment was conducted to investigate the effects of pit-run rock and washed cobble on vegetation and soil moisture. The success of various seed mixtures, transplanting and irrigation levels were evaluated. Total cover changed negligibly from the first growing season to the next, but the structure of the vegetation changed markedly. Moderate levels of irrigation increased the establishment of perennial grasses and shrubs. Rock placed on the surface prior to planting resulted in increased cover of weeds, shrubs and forbs and decreased grass cover relative to soil without surface rock. The most successful seed mixture was one of predominantly shrub and forb species adapted to the local environment. No significant differences in soil moisture were found between surface cover types. 6 references, 7 figures

DISPERSAL OF SEEDS AS NEST MATERIAL BY THE CACTUS WREN

Science.gov (United States)

Cactus wren (Campylorhynchus brunneicapillus) nests from the southern Chihuahuan Desert contained viable seeds of grasses, forbs, and shrubs. The most common plants used as construction material in these nests were Muhlenbergia porteri, Boerhavia spicata, and the alien grass Era...

Evaluating nurse plants for restoring native woody species to degraded subtropical woodlands.

Science.gov (United States)

Yelenik, Stephanie G; DiManno, Nicole; D'Antonio, Carla M

2015-01-01

Harsh habitats dominated by invasive species are difficult to restore. Invasive grasses in arid environments slow succession toward more desired composition, yet grass removal exacerbates high light and temperature, making the use of "nurse plants" an appealing strategy. In this study of degraded subtropical woodlands dominated by alien grasses in Hawai'i, we evaluated whether individuals of two native (Dodonaea viscosa, Leptocophylla tameiameia) and one non-native (Morella faya) woody species (1) act as natural nodes of recruitment for native woody species and (2) can be used to enhance survivorship of outplanted native woody species. To address these questions, we quantified the presence and persistence of seedlings naturally recruiting beneath adult nurse shrubs and compared survival and growth of experimentally outplanted seedlings of seven native woody species under the nurse species compared to intact and cleared alien-grass plots. We found that the two native nurse shrubs recruit their own offspring, but do not act as establishment nodes for other species. Morella faya recruited even fewer seedlings than native shrubs. Thus, outplanting will be necessary to increase abundance and diversity of native woody species. Outplant survival was the highest under shrubs compared to away from them with few differences between nurse species. The worst habitat for native seedling survival and growth was within the unmanaged invasive grass matrix. Although the two native nurse species did not differentially affect outplant survival, D. viscosa is the most widespread and easily propagated and is thus more likely to be useful as an initial nurse species. The outplanted species showed variable responses to nurse habitats that we attribute to resource requirements resulting from their typical successional stage and nitrogen fixation capability.

A Two-Year Study on Mercury Fluxes from the Soil under Different Vegetation Cover in a Subtropical Region, South China

Directory of Open Access Journals (Sweden)

Ming Ma

2018-01-01

Full Text Available In order to reveal the mercury (Hg emission and exchange characteristics at the soil–air interface under different vegetation cover types, the evergreen broad-leaf forest, shrub forest, grass, and bare lands of Simian Mountain National Nature Reserve were selected as the sampling sites. The gaseous elementary mercury (GEM fluxes at the soil–air interface under the four vegetation covers were continuously monitored for two years, and the effect of temperature and solar radiation on GEM fluxes were also investigated. Results showed that the GEM fluxes at the soil–air interface under different vegetation cover types had significant difference (p < 0.05. The bare land had the maximum GEM flux (15.32 ± 10.44 ng·m−2·h−1, followed by grass land (14.73 ± 18.84 ng·m−2·h−1, and shrub forest (12.83 ± 10.22 ng·m−2·h−1, and the evergreen broad-leaf forest had the lowest value (11.23 ± 11.13 ng·m−2·h−1. The GEM fluxes at the soil–air interface under different vegetation cover types showed similar regularity in seasonal variation, which mean that the GEM fluxes in summer were higher than that in winter. In addition, the GEM fluxes at the soil–air interface under the four vegetation covers in Mt. Simian had obvious diurnal variations.

The Study of Perennial Grasses and Legumes Mixtures in the Environmental Conditions Part 1: The Evolution of Mixtures Productivity from Someşelor Plateau

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Dorin-Benone Pleşa

2012-05-01

Full Text Available Lately it is a high interest in the establishing of temporary grasslands, these being considered a valuable source of fodder from the quantitative and qualitative point of view. Temporary grasslands can be established instead of degraded permanent grasslands or in arable lands. In the paper are presented the results of the research which took place in 2010 and 2011, regarding the fodder evolution of a double factor experience; A factor – mixtures (8 complex mixtures of perennial grasses and legumes and one alfalfa pure crop, considered as a witness,B factor – levels of fertilization (0N0P2O5, 60N70P2O5,120N70P2O5 kg·ha-1. In 2010 the highest productions (13.16 SU t·ha-1 were obtained at all the cycles from the 5th mixture composed from red clover and 4 species of grasses Trifolium pratense L., Dactylis glomerata L., Festulolium Asch. & Graebn., Phleum pratense L., Lolium perenne L.. In 2011, mixture number 3, recognized as being recommended for the forest steppe area and composed from Lotus corniculatus L.,Onobrychis viciifolia Scop., Dactylis glomerata L., Festuca pratensis Huds., Bromus inermis Leyss, presented the highest productions (4.82 t·ha-1 for the 60N70P2O5 and 120N70P2O5 kg·ha-1 levels of fertilization.

Living with aliens: effects of invasive shrub honeysuckles on avian nesting.

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Jason M Gleditsch

Full Text Available Invasive species have come to the forefront of conservation biology as a major threat to native biodiversity. Habitats dominated by shrub honeysuckles (Lonicera spp. in the United States have been characterized as "ecological traps" by ecologists. Here we tested this hypothesis by investigating the effects of shrub honeysuckles on the nesting ecology of native birds in seven study sites in central Pennsylvania, USA. We examined how the abundance of shrub honeysuckles influenced the selection of nesting substrates and habitat for a community of common songbirds, and the parental-care behavior and nestling development of gray catbirds (Dumetella carolinensis. We found that birds had a strong bias towards nesting in honeysuckle shrubs, but not necessarily for nesting in honeysuckle-dominated habitats. Nest predation rates were affected by the density of nests in a habitat, but not by the overall abundance of honeysuckles in such habitats. Honeysuckle abundance in the habitat did show significant effects on some parental-care behavioral parameters: catbirds had higher nest visitation rates and shorter visit lengths in areas of high honeysuckle density. On average, Gray catbirds fed fruit 12%±0.31 s.e. of their nestling-feeding bouts, mostly fruits of shrub honeysuckles. Nestlings in sites with high honeysuckle density also showed higher mass:tarsus ratios, suggesting a good (possibly better physiological condition of catbird nestlings at the time of fledging. Our study shows that honeysuckle-dominated habitats could have equivocal effects on nesting parameters of common species of native birds. We advise more caution in the widespread denomination of novel plant communities with high densities of honeysuckle as "ecological traps" as effects can be null or positive on native birds in certain localities.

Projecting the Dependence of Sage-steppe Vegetation on Redistributed Snow in a Warming Climate.

Science.gov (United States)

Soderquist, B.; Kavanagh, K.; Link, T. E.; Seyfried, M. S.; Strand, E. K.

2015-12-01

In mountainous regions, the redistribution of snow by wind can increase the effective precipitation available to vegetation. Moisture subsidies caused by drifting snow may be critical to plant productivity in semi-arid ecosystems. However, with increasing temperatures, the distribution of precipitation is becoming more uniform as rain replaces drifting snow. Understanding the ecohydrological interactions between sagebrush steppe vegetation communities and the heterogeneous distribution of soil moisture is essential for predicting and mitigating future losses in ecosystem diversity and productivity in regions characterized by snow dominated precipitation regimes. To address the dependence of vegetation productivity on redistributed snow, we simulated the net primary production (NPP) of aspen, sagebrush, and C3 grass plant functional types spanning a precipitation phase (rain:snow) gradient in the Reynolds Creek Experimental Watershed and Critical Zone Observatory (RCEW-CZO). The biogeochemical process model Biome-BGC was used to simulate NPP at three sites located directly below snowdrifts that provide melt water late into the spring. To assess climate change impacts on future plant productivity, mid-century (2046-2065) NPP was simulated using the average temperature increase from the Multivariate Adaptive Constructed Analogs (MACA) data set under the RCP 8.5 emission scenario. At the driest site, mid-century projections of decreased snow cover and increased growing season evaporative demand resulted in limiting soil moisture up to 30 and 40 days earlier for aspen and sage respectively. While spring green up for aspen occurred an average of 13 days earlier under climate change scenarios, NPP remained negative up to 40 days longer during the growing season. These results indicate that the loss of the soil moisture subsidy stemming from prolonged redistributed snow water resources can directly influence ecosystem productivity in the rain:snow transition zone.

Vegetation ecology and carbon sequestration potential of shrubs in tropics of Chhattisgarh, India.

Science.gov (United States)

Jhariya, Manoj Kumar

2017-09-25

Tropical forests are well known to have great species diversity and contribute substantial share in terrestrial carbon (C) stocks worldwide. Shrubs are long-neglected life form in the forest ecosystem, playing many roles in the forest and human life. Shrub has great impact on vegetation attributes which in turn modify the C storage and capture. In the present investigation, an attempt has been made to explore the dynamics of shrub species in four fire regimes, viz. high, medium, low, and no fire zones of Bhoramdeo Wildlife Sanctuary of Kawardha forest division (Chhattisgarh), India. The variations in structure, diversity, biomass, productivity, and C sequestration potential in all the sites were quantified. The density and basal area of shrub varied from 1250 to 3750 individuals ha -1 and 2.79 to 4.92 m 2  ha -1 , respectively. The diversity indices showed that the value of Shannon index was highest in medium fire zone (3.77) followed by high, low, and no fire zones as 3.25, 3.12, and 2.32, respectively. The value of Simpson's index or concentration of dominance (Cd) ranged from 0.08 to 0.20, species richness from 0.56 to 1.58, equitability from 1.41 to 1.44, and beta diversity from 1.50 to 4.20, respectively. The total biomass and C storage ranged from 6.82 to 15.71 and from 2.93 to 6.76 t ha -1 , respectively. The shrub density, importance value index (IVI), and abundance to frequency ratio (A/F) significantly correlated between high fire and medium fire zone. The basal area was found to be significantly positively correlated between high fire and medium fire, and low and no fire zones, respectively. Two-way cluster analysis reflected various patterns of clustering due to influence of the forest fire which showed that some species have distant clustering while some have smaller cluster. Principal component analysis (PCA) reflects variable scenario with respect to shrub layer. Ventilago calyculata and Zizyphus rotundifolia showed higher correlation between

The phytosociological analysis of saline area of Tehsil Ferozewala ...

African Journals Online (AJOL)

By reintegrating these trees and shrubs back into agriculture landscape to reverse salinity such as Atriplex amnicla, Tamarix aphylla, Phoenix dactilifera, Prosopis spp. Susbenia bispinasa, Sesbenia sesbena, Casorina, Grewia asiatie, Psidium guava etc. The incorporation of these plants (grasses, shrubs and trees) into ...

Age distributions of Greenlandic dwarf shrubs support concept of negligible actuarial senescence

Czech Academy of Sciences Publication Activity Database

Dahlgren, J. P.; Rizzi, S.; Schweingruber, F. H.; Hellmann, L.; Büntgen, Ulf

2016-01-01

Roč. 7, č. 10 (2016), č. článku e01521. ISSN 2150-8925 R&D Projects: GA MŠk(CZ) EE2.3.20.0248 Institutional support: RVO:67179843 Keywords : actuarial senescence * age distribution * age structure * Arctic dwarf shrubs * dendroecology * individual survival * mortality * penalized composite link model * plant aging * shrub demography Subject RIV: EH - Ecology, Behaviour Impact factor: 2.490, year: 2016

Gulf-Wide Information System, Environmental Sensitivity Index Scrub-Shrub and Wetlands, Geographic NAD83, LDWF (2001) [esi_scrub-shrub_wetland_LDWF_2001

Data.gov (United States)

Louisiana Geographic Information Center — This data set contains Environmental Sensitivity Index (ESI) scrub-shrub and wetlands data of coastal Louisiana. The ESI is a classification and ranking system,...

Conservation state of populations of rare plant species in highly transformed meadow steppes of Southern Opillya

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I. I. Dmytrash-Vatseba

2016-09-01

Full Text Available Degradation of natural habitats causes rapid extinction of rare plant populations. The diversity of rare plant species in the meadow steppes of Southern Opillya (Western Ukraine depends strongly on patch area, pasture digression of vegetation and a variety of eco-coenotical conditions. The main threats for the rare components of the meadow steppe flora are reduction of habitat and overgrazing. Spatial connections between sites are unable to support a constant rare plant population. The analysis of the composition of rare plant meadow-steppe species indicated that habitats with similar rare species composition usually have similar parameters of area, stages of pasture digression and eco-coenotical conditions. Spatial connectivity of patches does not ensure species similarity of rare components of the flora. Rare plant species were grouped according to their preferences for habitat , area and condition. In small patches subject to any stage of pasture digression grow populations of Adonis vernalis L., Pulsatilla patens (L. Mill., P. grandis Wender., Stipa capillata L., S. рennata L., Chamaecytisus blockianus (Pawł. Klásková etc. On the contrary, populations of other species (Carlina onopordifolia Besser. ex Szafer., Kuecz. et Pawł., Adenophora liliifolia (L. Ledeb. ex A. DC., Crambe tataria Sebeók, Euphorbia volhynica Besser ex Racib., Stipa tirsa Stev. etc. prefer large habitats, not changed by pasture digression. Prevention of reduction of rare species diversity requires preservation (also extension of patch area and regulation of grazing intensity.

Regional fire monitoring and characterization using global NASA MODIS fire products in dry lands of Central Asia

Science.gov (United States)

Loboda, Tatiana V.; Giglio, Louis; Boschetti, Luigi; Justice, Christopher O.

2012-06-01

Central Asian dry lands are grass- and desert shrub-dominated ecosystems stretching across Northern Eurasia. This region supports a population of more than 100 million which continues to grow at an average rate of 1.5% annually. Dry steppes are the primary grain and cattle growing zone within Central Asia. Degradation of this ecosystem through burning and overgrazing directly impacts economic growth and food supply in the region. Fire is a recurrent disturbance agent in dry lands contributing to soil erosion and air pollution. Here we provide an overview of inter-annual and seasonal fire dynamics in Central Asia obtained from remotely sensed data. We evaluate the accuracy of the Moderate Resolution Imaging Spectroradiometer (MODIS) global fire products within Central Asian dry lands and use these products to characterize fire occurrence between 2001 and 2009. The results show that on average ˜15 million ha of land burns annually across Central Asia with the majority of the area burned in August and September in grasslands. Fire is used as a common crop residue management practice across the region. Nearly 89% of all burning occurs in Kazakhstan, where 5% and 3% of croplands and grasslands, respectively, are burned annually.

Napa River Salt Marsh Restoration Project. Volume 1: Environmental Impact Statement

Science.gov (United States)

2004-06-01

Spartina alternifolia), which outcompetes and hybridizes with the native California cord grass. Coon Island, however, immediately adjacent to ponds in...sweet fennel (Foeniculum vulgare), and prickly lettuce . Urban Urban vegetation is dominated by landscaped grasses, flowers, shrubs, and trees, both

Genetic compatibility determines endophyte-grass combinations.

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Kari Saikkonen

Full Text Available Even highly mutually beneficial microbial-plant interactions, such as mycorrhizal- and rhizobial-plant exchanges, involve selfishness, cheating and power-struggles between the partners, which depending on prevailing selective pressures, lead to a continuum of interactions from antagonistic to mutualistic. Using manipulated grass-endophyte combinations in a five year common garden experiment, we show that grass genotypes and genetic mismatches constrain genetic combinations between the vertically (via host seeds transmitted endophytes and the out-crossing host, thereby reducing infections in established grass populations. Infections were lost in both grass tillers and seedlings in F(1 and F(2 generations, respectively. Experimental plants were collected as seeds from two different environments, i.e., meadows and nearby riverbanks. Endophyte-related benefits to the host included an increased number of inflorescences, but only in meadow plants and not until the last growing season of the experiment. Our results illustrate the importance of genetic host specificity and trans-generational maternal effects on the genetic structure of a host population, which act as destabilizing forces in endophyte-grass symbioses. We propose that (1 genetic mismatches may act as a buffering mechanism against highly competitive endophyte-grass genotype combinations threatening the biodiversity of grassland communities and (2 these mismatches should be acknowledged, particularly in breeding programmes aimed at harnessing systemic and heritable endophytes to improve the agriculturally valuable characteristics of cultivars.

Increased spring freezing vulnerability for alpine shrubs under early snowmelt.

Science.gov (United States)

Wheeler, J A; Hoch, G; Cortés, A J; Sedlacek, J; Wipf, S; Rixen, C

2014-05-01

Alpine dwarf shrub communities are phenologically linked with snowmelt timing, so early spring exposure may increase risk of freezing damage during early development, and consequently reduce seasonal growth. We examined whether environmental factors (duration of snow cover, elevation) influenced size and the vulnerability of shrubs to spring freezing along elevational gradients and snow microhabitats by modelling the past frequency of spring freezing events. We sampled biomass and measured the size of Salix herbacea, Vaccinium myrtillus, Vaccinium uliginosum and Loiseleuria procumbens in late spring. Leaves were exposed to freezing temperatures to determine the temperature at which 50% of specimens are killed for each species and sampling site. By linking site snowmelt and temperatures to long-term climate measurements, we extrapolated the frequency of spring freezing events at each elevation, snow microhabitat and per species over 37 years. Snowmelt timing was significantly driven by microhabitat effects, but was independent of elevation. Shrub growth was neither enhanced nor reduced by earlier snowmelt, but decreased with elevation. Freezing resistance was strongly species dependent, and did not differ along the elevation or snowmelt gradient. Microclimate extrapolation suggested that potentially lethal freezing events (in May and June) occurred for three of the four species examined. Freezing events never occurred on late snow beds, and increased in frequency with earlier snowmelt and higher elevation. Extrapolated freezing events showed a slight, non-significant increase over the 37-year record. We suggest that earlier snowmelt does not enhance growth in four dominant alpine shrubs, but increases the risk of lethal spring freezing exposure for less freezing-resistant species.

Detecting the differences in responses of stomatal conductance to moisture stresses between deciduous shrubs and Artemisia subshrubs.

Science.gov (United States)

Gao, Qiong; Yu, Mei; Zhou, Chan

2013-01-01

Shrubs and subshrubs can tolerate wider ranges of moisture stresses in both soil and air than other plant life forms, and thus represent greater nonlinearity and uncertainty in ecosystem physiology. The objectives of this paper are to model shrub/subshrub stomatal conductance by synthesizing the field leaf gas exchanges data of 24 species in China, in order to detect the differences between deciduous shrubs and Artemisia subshrubs in their responses of stomatal conductance to changes in the moisture stresses. We revised a model of stomatal conductance by incorporating the tradeoff between xylem hydraulic efficiency and cavitation loss risk. We then fit the model at the three hierarchical levels: global (pooling all data as a single group), three functional groups (deciduous non-legume shrubs, deciduous legume shrubs, and subshrubs in Artemisia genus), and individual observations (species × sites). Bayesian inference with Markov Chain Monte Carlo method was applied to obtain the model parameters at the three levels. We found that the model at the level of functional groups is a significant improvement over that at the global level, indicating the significant differences in the stomatal behavior among the three functional groups. The differences in tolerance and sensitivities to changes in moisture stresses are the most evident between the shrubs and the subshrubs: The two shrub groups can tolerate much higher soil water stress than the subshrubs. The analysis at the observation level is also a significant improvement over that at the functional group level, indicating great variations within each group. Our analysis offered a clue for the equivocal issue of shrub encroachment into grasslands: While the invasion by the shrubs may be irreversible, the dominance of subshrubs, due to their lower resistance and tolerance to moisture stresses, may be put down by appropriate grassland management.

Preliminary Results of Clover and Grass Coverage and Total Dry Matter Estimation in Clover-Grass Crops Using Image Analysis

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Anders K. Mortensen

2017-12-01

Full Text Available The clover-grass ratio is an important factor in composing feed ratios for livestock. Cameras in the field allow the user to estimate the clover-grass ratio using image analysis; however, current methods assume the total dry matter is known. This paper presents the preliminary results of an image analysis method for non-destructively estimating the total dry matter of clover-grass. The presented method includes three steps: (1 classification of image illumination using a histogram of the difference in excess green and excess red; (2 segmentation of clover and grass using edge detection and morphology; and (3 estimation of total dry matter using grass coverage derived from the segmentation and climate parameters. The method was developed and evaluated on images captured in a clover-grass plot experiment during the spring growing season. The preliminary results are promising and show a high correlation between the image-based total dry matter estimate and the harvested dry matter ( R 2 = 0.93 with an RMSE of 210 kg ha − 1 .

HIGH FOLIAR NITROGEN IN DESERT SHRUBS: AN IMPORTANT ECOSYSTEM TRAIT OR DEFECTIVE DESERT DOCTRINE?

Science.gov (United States)

Nitrogen concentrations in green and senesced leaves of perennial desert shrubs were compiled from a worldwide literature search to test the validity of the doctrine that desert shrubs produce foliage and leaf litter much richer in nitrogen than that in the foliage of plants from...

Response and Resiliency of Wildlife and Vegetation to Large-Scale Wildfires and Climate Change in the North Cascades

Science.gov (United States)

Bartowitz, K.; Morrison, P.; Romain-Bondi, K.; Smith, C. W.; Warne, L.; McGill, D.

2016-12-01

aid in management of the state-threatened species. The combination of severe fire and extreme heat/drought may result in shifts from shrub-steppe to grass/forb communities, as well as range contraction of ponderosa pine forests. The study reveals the importance of subsequent climatic conditions on vegetation recovery after a fire.

Effects of an experimental increase of temperature and drought on the photosynthetic performance of two ericaceous shrub species along a north-south European gradient

DEFF Research Database (Denmark)

Llorens, L.; Penuelas, J.; Beier, C.

2004-01-01

ericaceous shrubs (Erica multiflora and Calluna vulgaris) along a European gradient of temperature and precipitation (UK, Denmark, The Netherlands, and Spain). At each site, a passive warming treatment was applied during the night throughout the whole year, whereas the drought treatment excluded rain events...

Tree and shrub expansion over the past 34 years at the tree-line near Abisko, Sweden.

Science.gov (United States)

Rundqvist, Sara; Hedenås, Henrik; Sandström, Anneli; Emanuelsson, Urban; Eriksson, Håkan; Jonasson, Christer; Callaghan, Terry V

2011-09-01

Shrubs and trees are expected to expand in the sub-Arctic due to global warming. Our study was conducted in Abisko, sub-arctic Sweden. We recorded the change in coverage of shrub and tree species over a 32- to 34-year period, in three 50 x 50 m plots; in the alpine-tree-line ecotone. The cover of shrubs and trees (tree stems (> or =3.5 cm) were noted and positions determined. There has been a substantial increase of cover of shrubs and trees, particularly dwarf birch (Betula nana), and mountain birch (Betula pubescens ssp. czerepanovii), and an establishment of aspen (Populus tremula). The other species willows (Salix spp.), juniper (Juniperus communis), and rowan (Sorbus aucuparia) revealed inconsistent changes among the plots. Although this study was unable to identify the causes for the change in shrubs and small trees, they are consistent with anticipated changes due to climate change and reduced herbivory.

Ungulate browsing maintains shrub diversity in the absence of episodic disturbance in seasonally-arid conifer forest.

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Burak K Pekin

Full Text Available Ungulates exert a strong influence on the composition and diversity of vegetation communities. However, little is known about how ungulate browsing pressure interacts with episodic disturbances such as fire and stand thinning. We assessed shrub responses to variable browsing pressure by cattle and elk in fuels treated (mechanical removal of fuels followed by prescribed burning and non-fuels treated forest sites in northeastern Oregon, US. Seven treatment paddocks were established at each site; three with cattle exclusion and low, moderate and high elk browsing pressure, three with elk exclusion and low, moderate and high cattle browsing pressure, and one with both cattle and elk exclusion. The height, cover and number of stems of each shrub species were recorded at multiple plots within each paddock at the time of establishment and six years later. Changes in shrub species composition over the six year period were explored using multivariate analyses. Generalized Linear Mixed Models were used to determine the effect of browsing pressure on the change in shrub diversity and evenness. Vegetation composition in un-browsed paddocks changed more strongly and in different trajectories than in browsed paddocks at sites that were not fuels treated. In fuels treated sites, changes in composition were minimal for un-browsed paddocks. Shrub diversity and evenness decreased strongly in un-browsed paddocks relative to paddocks with low, moderate and high browsing pressure at non-fuels treated sites, but not at fuels treated sites. These results suggest that in the combined absence of fire, mechanical thinning and ungulate browsing, shrub diversity is reduced due to increased dominance by certain shrub species which are otherwise suppressed by ungulates and/or fuels removal. Accordingly, ungulate browsing, even at low intensities, can be used to suppress dominant shrub species and maintain diversity in the absence of episodic disturbance events.

Summer warming and changes in snow depth is reflected in the growth rings of Alaskan tundra shrubs (Toolik Lake)

Science.gov (United States)

Buchwal, A.; Welker, J. M.

2016-12-01

Arctic change is being manifested by shifts in the vegetation composition and abundance throughout many regions of the Arctic. These changes are primarily reflected by increases in shrub growth and density, but the extent to which shrub growth is expressed in greater shrub ring width and the degree to which natural and experimental warming correspond and or whether the secondary effect of deeper snow in winter acts to alter shrub ring growh and or shrub biomass is yet to be determined for Arctic Alaska. In order to explore growth response of arctic shrubs to on-going and predicted temperature and snow depth increase we investigated shrubs' annual growth rings using dendrochronological methods applied to plants growing under control and experimental treatments in Toolik Lake, Northern Alaska. Specifically we evaluated the effects of a 20-year experimental warming (due to open top chambers, OTC's) and snow depth increases on the growth rings pattern of two common shrub species of Northern Alaska, i.e. Betula nana and Salix pulchra. By applying a serial sectioning method patterns of annual growth were investigated across the entire plant including below-ground parts. Moreover this procedure allowed for a complete cross-dating and a detection of irregular radial growth, including common missing and partially missing rings. We found that the natural warming in Alaska occurring over the past 20 years is stimulating shrub ring growth, more so for Betula than for Salix. Experimental warming (simulating conditions in approximately 2030) stimulated the secondary growth ratio; however the allocation pattern between below-ground and above-ground is quite variable between individual shrubs. In addition, annual growth rings analyses were supplemented by quantitative wood anatomy properties, such as vessel size and density. Our findings indicate that there can be differential growth ring responses of deciduous shrubs to natural climate warming, that growth ring increases reflect

Long-term effects of seeding after wildfire on vegetation in Great Basin shrubland ecosystems

Science.gov (United States)

Knutson, Kevin C.; Pyke, David A.; Wirth, Troy A.; Arkle, Robert S.; Pilliod, David S.; Brooks, Matthew L.; Chambers, Jeanne C.; Grace, James B.

2014-01-01

1. Invasive annual grasses alter fire regimes in shrubland ecosystems of the western USA, threatening ecosystem function and fragmenting habitats necessary for shrub-obligate species such as greater sage-grouse. Post-fire stabilization and rehabilitation treatments have been administered to stabilize soils, reduce invasive species spread and restore or establish sustainable ecosystems in which native species are well represented. Long-term effectiveness of these treatments has rarely been evaluated. 2. We studied vegetation at 88 sites where aerial or drill seeding was implemented following fires between 1990 and 2003 in Great Basin (USA) shrublands. We examined sites on loamy soils that burned only once since 1970 to eliminate confounding effects of recurrent fire and to assess soils most conducive to establishment of seeded species. We evaluated whether seeding provided greater cover of perennial seeded species than burned–unseeded and unburned–unseeded sites, while also accounting for environmental variation. 3. Post-fire seeding of native perennial grasses generally did not increase cover relative to burned–unseeded areas. Native perennial grass cover did, however, increase after drill seeding when competitive non-natives were not included in mixes. Seeding non-native perennial grasses and the shrub Bassia prostrata resulted in more vegetative cover in aerial and drill seeding, with non-native perennial grass cover increasing with annual precipitation. Seeding native shrubs, particularly Artemisia tridentata, did not increase shrub cover or density in burned areas. Cover of undesirable, non-native annual grasses was lower in drill seeded relative to unseeded areas, but only at higher elevations. 4. Synthesis and applications. Management objectives are more likely to be met in high-elevation or precipitation locations where establishment of perennial grasses occurred. On lower and drier sites, management objectives are unlikely to be met with seeding alone