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Maintaining the native prairie lands of the Northern Great Plains (NGP), which provide an important habitat for declining grassland species, requires anticipating the effects of increasing atmospheric carbon dioxide (CO2) concentrations and climate change on the region’s vegetation. Specifically, climate change threatens NGP grasslands by increasing the potential encroachment of native woody species into areas where they were previously only present in minor numbers. This project used a dynamic vegetation model to simulate vegetation type (grassland, shrubland, woodland, and forest) for the NGP for a range of projected future climates and relevant management scenarios. Comparing results of these simulations illustrates...
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We used field studies and imaging spectroscopy to investigate the effect of grazing on vegetation cover in historically grazed and ungrazed high-mesa rangelands of the Grand Staircase?Escalante National Monument, Utah, USA. Airborne hyperspectral remote sensing data coupled with spectral mixture analysis uncovered subtle variations in the key biogeophysical properties of these rangelands: the fractional surface cover of photosynthetic vegetation (PV), nonphotosynthetic vegetation (NPV), and bare soil. The results show that a high-mesa area with long-term grazing management had significantly higher PV (26.3%), lower NPV (54.5%), and lower bare soil (17.2%) cover fractions in comparison to historically ungrazed high-mesa...
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Over the last century there has been marked expansion and infilling of pinyon (Pinus spp.)–juniper (Juniperus spp.) woodlands into grassland and shrubland ecosystems across the western United States. Although range expansions in pinyon-juniper populations have been documented with changing climate throughout the Holocene, over the last century, local scale impacts such as livestock grazing, changes in fire regimes, and increasing atmospheric CO2 concentrations are thought to be more recent drivers of pinyon-juniper woodland distribution. Our objective was to examine the role of historical livestock grazing relative to past climate in regulating pinyon (Pinus edulis Engelm.) recruitment and growth over the last...
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Over the past several decades, the expansion and thickening of woodlands in the western United States has caused a range of ecological changes. Woody expansion often leads to increases in soil organic matter (SOM) pools with implications for both biogeochemical cycling and ecological responses to management strategies aimed at restoration of rangeland ecosystems. Here we directly measure C and N stocks and use simple non-steady-state models to quantify the dynamics of soil C accumulation under and around trees of varied ages in southern Utah woodlands. In the two pinyon-juniper forests of Grand Staircase Escalante National Monument studied here, we found approximately 3 kg C/m2 and approximately 0.12 kg N/m2 larger...
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This data set contains output from the dynamic vegetation model MC1, as modified to simulate future woody encroachment in the northern Great Plains, for 23 monthly variables, 63 yearly variables, and 31 multi-year variables. Variables include simulated plant (by growth form) and soil carbon stocks, net primary production, vegetation type, potential and actual evapotranspiration, stream flow, and fuel mass and moisture. Model output is provided for the EQ, Spinup, Historical, and Future stages of MC1 runs; future stages were run for four climate projections crossed with 10 or 11 fire X grazing X CO2 concentration scenarios for the western and eastern portions of the study area, respectively.
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...
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The dynamic global vegetation model MC1 simulates plant growth and biogeochemical cycles, vegetation type, wildfire, and their interactions. The model simulates competition between trees and grasses (including other herbaceous species), as affected by differential access to light and water, and fire-caused tree mortality (Bachelet et al., 2000; 2001). MC1 projects the dynamics of lifeforms, including evergreen and deciduous needleleaf and broadleaf trees, as well as C3 and C4 grasses. However, the model can also be parameterized for a particular dominant species of the associated lifeform. For this project we used two versions of MC1, both of which modified the standard code to improve the simulation of potential...
Conclusions:Influx of woody vegetation associated with fragmentation correlates with decline in grassland bird speciesThresholds/Learnings:When native grassland cover dropped below 60% at one site, and 30-40% at another site, the arrangement or habitat patches became more important to the survival of populations than habitat amount alone
Understanding the terrestrial carbon budget, in particular the strength of the terrestrial carbon sink, is important in the context of global climate change. Considerable attention has been given to woody encroachment in the western US and the role it might play as a carbon sink; however, in many parts of the western US the reverse process is also occurring. The conversion of woody shrublands to annual grasslands involves the invasion of non-native cheatgrass (Bromus tectorum) which in turn leads to increased frequency and extent of fires. We compared carbon storage in adjacent plots of invasive grassland and native shrubland. We scaled-up the impact of this ecosystem shift using regional maps of the current invasion...


    map background search result map search result map Influence of Livestock Grazing and Climate on Pinyon Pine (Pinus edulis) Dynamics - Rangeland Ecology & Management Soil carbon storage responses to expanding pinyon–juniper populations in southern Utah Changes in Vegetation Structure after Long-term Grazing in Pinyon-Juniper Ecosystems: Integrating Imaging Spectroscopy and Field Studies Projecting the Future Encroachment of Woody Vegetation into Grasslands of the Northern Great Plains by Simulating Climate Conditions and Possible Management Actions Output from MC1 Model Modified to Simulate Future Woody Encroachment in the Northern Great Plains MC1 Code Modified to Simulate Future Woody Encroachment in the Northern Great Plains Changes in Vegetation Structure after Long-term Grazing in Pinyon-Juniper Ecosystems: Integrating Imaging Spectroscopy and Field Studies Influence of Livestock Grazing and Climate on Pinyon Pine (Pinus edulis) Dynamics - Rangeland Ecology & Management Soil carbon storage responses to expanding pinyon–juniper populations in southern Utah Output from MC1 Model Modified to Simulate Future Woody Encroachment in the Northern Great Plains MC1 Code Modified to Simulate Future Woody Encroachment in the Northern Great Plains Projecting the Future Encroachment of Woody Vegetation into Grasslands of the Northern Great Plains by Simulating Climate Conditions and Possible Management Actions