6 research outputs found
Long-Term Effectiveness of Tree Removal to Re-Establish Sagebrush Steppe Vegetation and Associated Spatial Patterns in Surface Conditions and Soil Hydrologic Properties
Pinyon (Pinus spp.) and juniper (Juniperus spp.) woodland encroachment into sagebrush (Artemisia spp.) steppe communities throughout western North America has substantially altered the vegetation structure and hydrologic function of one of the most ecologically important rangeland ecosystems in the world. Various pinyon and juniper tree removal practices are employed to re-establish sagebrush steppe vegetation and an associated resource-conserving ecohydrologic function. The effectiveness of these practices is highly variable owing to the vast domain in which woodland encroachment occurs, climate fluctuations, differences in treatment applications, and myriads of pre-treatment conditions and post-treatment land uses. This study evaluated the long-term (13 years post-treatment) effectiveness of prescribed fire and mechanical tree removal to re-establish sagebrush steppe vegetation and associated spatial patterns in ground surface conditions and soil hydrologic properties of two woodland-encroached sites. Specifically, we assessed the effects of tree removal on: (1) vegetation and ground cover at the hillslope scale (990 m2 plots) and (2) associated spatial patterns in point-scale ground surface conditions and soil hydrologic properties along transects extending from tree bases and into the intercanopy areas between trees. Both sites were in mid to late stages of woodland encroachment with extensive bare conditions (~60–80% bare ground) throughout a degraded intercanopy area (~75% of the domain) surrounding tree islands (~25% of domain, subcanopy areas). All treatments effectively removed mature tree cover and increased hillslope vegetation. Enhanced herbaceous cover (4–15-fold increases) in burned areas reduced bare interspace (bare area between plants) by at least 4-fold and improved intercanopy hydraulic conductivity (\u3e than 2-fold) and overall ecohydrologic function. Mechanical treatments retained or increased sagebrush and generally increased the intercanopy herbaceous vegetation. Intercanopy ground surface conditions and soil hydrologic properties in mechanical treatments were generally similar to those in burned areas but were also statistically similar to the same measures in untreated areas in most cases. This suggests that vegetation and ground surface conditions in mechanical treatments are trending toward a significantly improved hydrologic function over time. Treatments had limited impact on soil hydrologic properties within subcanopy areas; however, burning did reduce the soil water repellency strength and the occurrence of strong soil water repellency underneath trees by three- to four-fold. Overall, the treatments over a 13-year period enhanced the vegetation, ground surface conditions, and soil hydrologic properties that promote infiltration and limit runoff generation for intercanopy areas representing ~75% of the area at the sites. However, ecological tradeoffs in treatment alternatives were evident. The variations in woodland responses across sites, treatments, and measurement scales in this long-term study illustrate the complexity in predicting vegetation and hydrologic responses to tree removal on woodland-encroached sagebrush sites and underpin the need and value of multi-scale long-term studies
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Kentucky bluegrass invaded rangeland: ecosystem implications and adaptive management approaches
USDA-NRCS National Resources Inventory data indicates that between 2011 and 2015 Kentucky bluegrass (Poa pratensis) was present in 14.5% on non-Federal rangelands nationally and 86% in North Dakota, 63% in South Dakota, 40% in Kansas, 38% in Nebraska, and 32% in Montana. Native grasslands provide important services such as nutrient cycling, forage and habitat for wildlife and livestock, pollinator habitat, carbon capture, and regulation of hydrologic cycles, among others. Therefore, grassland degradation due to invasive plant species has far-ranging consequences for both human and ecological systems. We present information from a symposium at the 2019 Society for Range Management Annual Meeting. The symposium covered three topic areas that have been the foci of NGP Kentucky bluegrass research in the last five years: (1) impacts of Kentucky bluegrass on ecosystem services (especially soil water regulation, pollinator services, and forage production); (2) opportunities for using adaptive management approaches that include natural disturbances (such as fire and livestock grazing) for restoring and maintaining diverse grasslands; and (3) how to effectively overcome social barriers to treatment options aimed at restoring these grasslands. We present brief summaries of research progress on these topics. We conclude that despite great advances in knowledge related to Kentucky bluegrass invaded ecosystems there are still knowledge gaps regarding management of this novel ecosystem under changing climatic conditions as well as challenges regarding large scale adoption of management practices needed to manage these systems appropriately
Introduction to the Special Issue “Ecohydrologic Feedbacks between Vegetation, Soil, and Climate”
Vegetation transitions on arid and semi-arid landscapes present unique opportunities for examining structural and functional (pattern and process) ecohydrologic feedbacks that regulate site ecological resilience [...
Introduction to the Special Issue “Ecohydrologic Feedbacks between Vegetation, Soil, and Climate”
Vegetation transitions on arid and semi-arid landscapes present unique opportunities for examining structural and functional (pattern and process) ecohydrologic feedbacks that regulate site ecological resilience [...
Long-Term Effectiveness of Tree Removal to Re-Establish Sagebrush Steppe Vegetation and Associated Spatial Patterns in Surface Conditions and Soil Hydrologic Properties
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Kentucky bluegrass invaded rangeland: Ecosystem implications and adaptive management approaches
Summary of multidisciplinary research on Kentucky bluegrass expansion throughout the Great Plains based on symposium held at 2019 SRM Annual Meeting. Fire, grazing, and their combination are promising tools for managing Kentucky bluegrass to maintain diverse and productive grasslands. Kentucky bluegrass growth and dominance results in accumulation of surface residues, which alter soil hydrology. Gradients of Kentucky bluegrass abundance in grasslands are associated with shifts in butterfly pollinator communities. Community organization, education, and establishment of burn associations support prescribed fire on the ground, but challenges in adopting fire as a management tool remain. © 2020 The Society for Range ManagementThe Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information