USGS - science for a changing world


David A Pyke

Supervisory Research Ecologist

Snake River Field Station, FRESC

Office Phone: 541-750-0989

Corvallis Research Group CFSL - IAA
3200 S.W. Jefferson Way
Corvallis , OR 97331

Supervisor: Sue Phillips
Drylands cover 40% of the global terrestrial surface and provide important ecosystem services. While drylands as a whole are expected to increase in extent and aridity in coming decades, temperature and precipitation forecasts vary by latitude and geographic region suggesting different trajectories for tropical, subtropical, and temperate drylands. Uncertainty in the future of tropical and subtropical drylands is well constrained, whereas soil moisture and ecological droughts, which drive vegetation productivity and composition, remain poorly understood in temperate drylands. Here we show that, over the twenty first century, temperate drylands may contract by a third, primarily converting to subtropical drylands,...
Categories: Publication; Types: Citation
Drylands occur world-wide and are particularly vulnerable to climate change since dryland ecosystems depend directly on soil water availability that may become increasingly limited as temperatures rise. Climate change will both directly impact soil water availability, and also change plant biomass, with resulting indirect feedbacks on soil moisture. Thus, the net impact of direct and indirect climate change effects on soil moisture requires better understanding. We used the ecohydrological simulation model SOILWAT at sites from temperate dryland ecosystems around the globe to disentangle the contributions of direct climate change effects and of additional indirect, climate change-induced changes in vegetation on...
Categories: Publication; Types: Citation
This Report provides a strategic approach for conservation of sagebrush ecosystems and Greater SageGrouse (sage-grouse) that focuses specifically on habitat threats caused by invasive annual grasses and altered fire regimes. It uses information on factors that influence (1) sagebrush ecosystem resilience to disturbance and resistance to invasive annual grasses and (2) distribution, relative abundance, and persistence of sage-grouse populations to develop management strategies at both landscape and site scales. A sage-grouse habitat matrix links relative resilience and resistance of sagebrush ecosystems with sage-grouse habitat requirements for landscape cover of sagebrush to help decision makers assess risks and...
Abstract: "Alien grass invasions in arid and semi-arid ecosystems are resulting in grass-fire cycles and ecosystem-level transformations that severely diminish ecosystem services. Our capacity to address the rapid and complex changes occurring in these ecosystems can be enhanced by developing an understanding of the environmental factors and ecosystem attributes that determine resilience of native ecosystems to stress and disturbance, and resistance to invasion. Cold desert shrublands occur over strong environmental gradients and exhibit significant differences in resilience and resistance. They provide an excellent opportunity to increase our understanding of these concepts. Herein, we examine a series of linked...
Categories: Data, Publication; Types: Citation
Proposed work will monitor for five years vegetation, fuels, wildlife, insects, and weather at 10 SageSTEP sites, all of which have been treated to reduce either juniper encroachment (woodland sites) or cheatgrass invasion (sagebrush/cheatgrass sites). Each of the six woodland sites contains an untreated control plot, a ‘cut’ plot where all trees were felled and left on site, and a prescribed burn plot, where fire was used to kill all trees – management objective of the treatments was to reduce tree dominance. Each of the four sagebrush/cheatgrass sites contains an untreated control plot, a mowed plot, a prescribed burn plot, and an herbicide plot, where each treatment was designed to remove 50% of the sagebrush...
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