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One of the major concerns about global warming is the potential for an increase in decomposition and soil respiration rates, increasing CO2 emissions and creating a positive feedback between global warming and soil respiration. This is particularly important in ecosystems with large belowground biomass, such as grasslands where over 90% of the carbon is allocated belowground. A better understanding of the relative influence of climate and litter quality on litter decomposition is needed to predict these changes accurately in grasslands. The Long-Term Intersite Decomposition Experiment Team (LIDET) dataset was used to evaluate the influence of climatic variables (temperature, precipitation, actual evapotranspiration,...
Implementation of the U.S. Department of Agriculture (USDA) Conservation Reserve Program (CRP) and Wetlands Reserve Program (WRP) has resulted in the restoration of >2 million ha of wetland and grassland habitats in the Prairie Pothole Region (PPR). Restoration of habitats through these programs provides diverse ecosystem services to society, but few investigators have evaluated the environmental benefits achieved by these programs. We describe changes in wetland processes, functions, and ecosystem services that occur when wetlands and adjacent uplands on agricultural lands are restored through Farm Bill conservation programs. At the scale of wetland catchments, projects have had positive impacts on water storage,...
Abstract (from http://www.nature.com/articles/srep24441): The 170 National Forests and Grasslands (NFs) in the conterminous United States are public lands that provide important ecosystem services such as clean water and timber supply to the American people. This study investigates the potential impacts of climate change on two key ecosystem functions (i.e., water yield and ecosystem productivity) using the most recent climate projections derived from 20 Global Climate Models (GCMs) of the Coupled Model Intercomparison Project phase 5 (CMIP5). We find that future climate change may result in a significant reduction in water yield but an increase in ecosystem productivity in NFs. On average, gross ecosystem productivity...
Increases in net primary production (NPP) may not necessarily result in increased C sequestration since an increase in uptake can be negated by concurrent increases in ecosystem C losses via respiratory processes. Continuous measurements of net ecosystem C exchange between the atmosphere and two experimental cheatgrass (Bromus tectorum L.) ecosystems in large dynamic flux chambers (EcoCELLs) showed net ecosystem C losses to the atmosphere in excess of 300 g C m?2 over two growing cycles. Even a doubling of net ecosystem production (NEP) after N fertilization in the second growing season did not compensate for soil C losses incurred during the fallow period. Fertilization not only increased C uptake in biomass but...
This study examined whether an individual plant's risk of herbivory was affected by its nearest neighbor. Individually potted tillers of Bouteloua gracilis were placed in a natural habitat with one of two neighbors (B. gracilis conspecifics or Aristida spp.), and in one of two cover treatments (high: in center of neighbor canopy, and low: at periphery of canopy). After one month, the experimental tillers were collected and scored for herbivory. We found that the less palatable neighbor, Aristida spp., reduced the probability that herbivores would feed upon experimental tillers in one of the two years of our study, but in both years increased the amount of feeding on those tillers that were attacked. The amount of...
The availability of nutrients is a critical determinant of ecological dynamics in grasslands, but the relationships between soil resource availability and nutrient limitation across ecosystems are not clear. To better understand how soil nutrient availability determines nutrient limitation in vegetation, we grew the same species of grass (Schizachyrium scoparium) in 98 North American grassland soils and fertilized them factorially with nitrogen (N) and phosphorus (P). On average adding N, P, and the two nutrients together increased biomass relative to unfertilized plants by 81%, 22%, and 131%, respectively. Plants grown on low-P soils were not primarily limited by P. Instead, these plants were colimited by N and...
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Habitat loss and fragmentation are widely recognized as among the most important threats to global biodiversity. New analytical approaches are providing improved ability to predict the effects of landscape change on population connectivity at vast spatial extents. This paper presents an analysis of population connectivity for three species of conservation concern [swift fox (Vulpes velox); lesser prairie-chicken (Tympanuchus pallidicinctus); massasuaga (Sistrurus catenatus)] across the American Great Plains region. We used factorial least-cost path and resistant kernel analyses to predict effects of landscape conditions on corridor network connectivity. Our predictions of population connectivity provide testable...
Categories: Data, Project, Publication; Types: Citation, Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: 2010, CO-01, CO-02, CO-03, CO-04, All tags...
Plant invasions have the potential to significantly alter soil microbial communities, given their often considerable aboveground effects. We examined how plant invasions altered the arbuscular mycorrhizal fungi of native plant roots in a grassland site in California and one in Utah. In the California site, we used experimentally created plant communities composed of exotic (Avena barbata, Bromus hordeaceus) and native (Nassella pulchra, Lupinus bicolor) monocultures and mixtures. In the Utah semi-arid grassland, we took advantage of invasion by Bromus tectorum into long-term plots dominated by either of two native grasses, Hilaria jamesii or Stipa hymenoides. Arbuscular mycorrhizal fungi colonizing roots were characterized...
We investigated the influence of long-term (56 years) grazing on organic and inorganic carbon (C) and nitrogen (N) contents of the plant-soil system (to 90 cm depth) in shortgrass steppe of northeastern Colorado. Grazing treatments included continuous season-long (May-October) grazing by yearling heifers at heavy (60-75% utilization) and light (20-35% utilization) stocking rates, and nongrazed exclosures. The heavy stocking rate resulted in a plant community that was dominated (75% of biomass production) by the C4 grass blue grama (Bouteloua gracilis), whereas excluding livestock grazing increased the production of C3 grasses and prickly pear cactus (Opuntia polycantha). Soil organic C (SOC) and organic N were not...
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The broadly shared information needs for grassland managers in the North Central region to meet conservation goals in a changing climate are presented and ranked as highly relevant, somewhat relevant, or not relevant for federal, state, tribal, and non-governmental grassland-managing entities.
Tortula ruralis is a homoiochlorophyllous-desiccation-tolerant (HDT) moss that retains all pigments when dehydrated and rapidly recovers physiological function upon rehydration. This moss forms extensive cover in exposed and shaded areas in the sandy semi-arid grasslands of Central Europe. We hypothesized that contrasting drying regimes between these microhabitats would affect-plant N status, constraints to gas exchange and growth, as well as result in altered pigment concentrations and ratios, and photochemical light-response dynamics. Furthermore, we believed T. ruralis's HDT habit would limit its ability to acclimate to altered light environment. We found that sun plant T. ruralis had lower plant mass, as well...
We evaluated the effects of livestock grazing on C content of the plant?soil system (to 60 cm) of two semi-arid grasslands: a mixed-grass prairie (grazed 12 years), and a short-grass steppe (grazed 56 years). Grazing treatments included season-long grazing at heavy and light stocking rates, and non-grazed exclosures. Significantly higher soil C (0?30cm) was measured in grazed pastures compared to non-grazed exclosures, although for the short-grass steppe higher soil C was observed with the heavy grazing treatment only. Excluding grazing caused an immobilization of C in excessive aboveground plant litter, and an increase in annual forbs and grasses which lack dense fibrous rooting systems conducive to soil organic...
The introduction of nonnative plant species may decrease ecosystem stability by altering the availability of nitrogen (N) for plant growth. Invasive species can impact N availability by changing litter quantity and quality, rates of N2-fixation, or rates of N loss. We quantified the effects of invasion by the annual grass Bromus tectorum on N cycling in an arid grassland on the Colorado Plateau (USA). The invasion occurred in 1994 in two community types in an undisturbed grassland. This natural experiment allowed us to measure the immediate responses following invasion without the confounding effects of previous disturbance. Litter biomass and the C:N and lignin:N ratios were measured to determine the effects on...
Shrub encroachment into grass-dominated biomes is occurring globally due to a variety of anthropogenic activities, but the consequences for carbon (C) inputs, storage and cycling remain unclear. We studied eight North American graminoid-dominated ecosystems invaded by shrubs, from arctic tundra to Atlantic coastal dunes, to quantify patterns and controls of C inputs via aboveground net primary production (ANPP). Across a fourfold range in mean annual precipitation (MAP), a key regulator of ecosystem C input at the continental scale, shrub invasion decreased ANPP in xeric sites, but dramatically increased ANPP (>1000gm-2) at high MAP, where shrub patches maintained extraordinarily high leaf area. Concurrently, the...
Water is a key driver of ecosystem processes in aridland ecosystems. Thus, changes in climate could have significant impacts on ecosystem structure and function. In the southwestern US, interactions among regional climate drivers (e.g., El Ni�o Southern Oscillation) and topographically controlled convective storms create a spatially and temporally variable precipitation regime that governs the rate and magnitude of ecosystem processes. We quantified the spatial and temporal distribution of reduced grassland greenness in response to seasonal and annual variation in precipitation at two scales at the Sevilleta Long Term Ecological Research site in central New Mexico, using Normalized Difference Vegetation Index (NDVI)...
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The introduction of nonnative plant species may decrease ecosystem stability by altering the availability of nitrogen (N) for plant growth. Invasive species can impact N availability by changing litter quantity and quality, rates of N2-fixation, or rates of N loss. We quantified the effects of invasion by the annual grass Bromus tectorum on N cycling in an arid grassland on the Colorado Plateau (USA). The invasion occurred in 1994 in two community types in an undisturbed grassland. This natural experiment allowed us to measure the immediate responses following invasion without the confounding effects of previous disturbance. Litter biomass and the C:N and lignin:N ratios were measured to determine the effects on...
This data set contains output from the dynamic vegetation model MC1, as modified to simulate future woody encroachment in the northern Great Plains. Simulations were done for the historical period (1895-2005) and the future period (2006-2100). Separate simulations were done for eastern and western portions of the region, with the eastern simulations using model parameters appropriate for Juniperus virginiana as the major evergreen needle-leaf life form, and the western simulations using model parameters appropriate for Pinus ponderosa as the major evergreen needle-leaf life form. Simulations in each portion were run for two A2 emissions scenario climate projections (CSIRO, representing moderate temperature increases...
Bromus tectorum is an exotic annual grass that currently dominates many western U.S. semi-arid ecosystems, and the effects of this grass on ecosystems in general, and soil biota specifically, are unknown. Bromus recently invaded two ungrazed and un-burned perennial bunchgrass communities in southeastern Utah. This study compared the soil food-web structure of the two native grassland associations (Stipa [S] and Hilaria [H]), with and without the presence of Bromus. Perennial grass and total vascular-plant cover were higher in S than in H plots, while quantities of ground litter were similar. Distribution of live and dead plant material was highly clumped in S and fairly homogenous in H. Soil food-web structure was...
map background search result map search result map Exotic plant invasion alters nitrogen dynamics in an arid grassland Climate change and connectivity: Assessing landscape and species vulnerability Broadly Shared Information Needs Among Grassland Managers in the North Central Region Exotic plant invasion alters nitrogen dynamics in an arid grassland Climate change and connectivity: Assessing landscape and species vulnerability Broadly Shared Information Needs Among Grassland Managers in the North Central Region