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Increases in the abundance or density of woody plants in historically semiarid and arid grassland ecosystems have important ecological, hydrological, and socioeconomic implications. Using a simplified water-balance model, we propose a framework for conceptualizing how woody plant encroachment is likely to affect components of the water cycle within these ecosystems. We focus in particular on streamflow and the partitioning of evapotranspiration into evaporation and transpiration. On the basis of this framework, we suggest that streamflow and evaporation processes are affected by woody plant encroachment in different ways, depending on the degree and seasonality of aridity and the availability of subsurface water....
Speaker: Dr. Keirith Snyder, USDA ARS, Great Basin Rangelands Research Unit, Reno, NV The opportunistic encroachment of native pinyon and juniper trees into areas formerly dominated by sagebrush has reduced the presence of shrubs and grasses, impacting critical habitat and forage availability. Pinyon and juniper currently occupy 19 million hectares in the Intermountain West. Prior to 1860, it is estimated that 2/3 of pinyon and juniper woodlands were sagebrush communities. This presentation will give an overview of the Porter Canyon Experimental Watershed, where tree-felling treatments are being studied. Porter Canyon is located in central Nevada in the Desatoya Mountains. A network of sensors has been installed...
Abstract (from http://www.sciencedirect.com/science/article/pii/S1146609X15300059): Woody species are increasing in density, causing transition to more densely wooded vegetation states, and encroaching across ecotonal borders into non-forested ecosystems. We examined USDA Forest Service Forest Inventory and Analysis data to identify tree species that have expanded longitudinally in range, particularly into the central United States. We analyzed compositional differences within ecological regions (i.e., subsections) in eastern and western ranges of species using repeated measures ANOVA. We considered differences in outer ranges to indicate range expansion or contraction. We also estimated the shift in forest area...
Stands of quaking aspen (Populus tremuloides) rank among the most biologically diverse plant communities across the intermountain region of western North America. Marked declines of aspen have occurred in recent decades, likely due to a combination of effects from changes in fire regimes, herbivory, climate (e.g. drought), and interspecific competition with conifer species. However, it is poorly understood how the effects of these factors are manifested at a landscape scale over decadal time periods. Analysis of field data combined with topographic information collected across the 500,000 ha Owyhee Plateau in southwestern Idaho revealed that aspen in the area occur in three different biophysical settings; First,...
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FY2013Pion (Pinus spp.) and juniper (Juniperus spp.) (PJ) currently occupy approximately 19 million hectars in the Intermountain West. Prior to 1860, approximately 66% of what is now woodland occurred as sagebrush plant communities.This watershed scale project: Documents the impact of PJ treatments in formerly sagebrush steppe communities on understory vegetation composition, hydrologic function, and surface runoff and soil erosion at the landscape scale. Expands the snow monitoring component to understand snow dynamics and timing of plant phenology in cut and uncut treatments. Secures expertise to analyze existing datasets.
    map background search result map search result map Desatoya Mountains Project and Porter Canyon Experimental Watershed Desatoya Mountains Project and Porter Canyon Experimental Watershed