Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Assessing the Impacts of Conservation Practices in the Rio Puerco Watershed

Auteur : Schallner, Jeremy Wayne

Université de soutenance : New Mexico State University

Grade : Master of Science (MS) 2019

Description
Since European settlement, the Rio Puerco Watershed has undergone substantial anthropogenic alterations. Historic overutilization of herbaceous vegetation and diversion of water resources through the late nineteenth century altered many plant communities, and the changes in plant community structure and composition negatively impacted many ecosystem services (e.g., forage production and erosion regulation) provided by this landscape. The main alteration to the plant communities was an increase in woody species, primarily Wyoming big sagebrush, which led to a reduction in the herbaceous component of the communities and an increase in the amount of bare soil. In response, the Natural Resources Conservation Service (NRCS) and the Bureau of Land Management (BLM) implement brush control conservation practices through aerial application of tebuthiuron, an herbicide designed to reduce overly dense woody species, to increase herbaceous cover and reduce erosion. For two areas treated with tebuthiuron and two untreated areas for comparison of treatment effects, we developed a long-term monitoring plan. Short-term plant community structure responses included an increase in basal gaps over 20 cm and suppression of herbaceous biomass production on the treated areas. Two years following treatment, big sagebrush density decreased to 11% of pre-treatment levels. A detrended correspondence analysis of plant community composition revealed a shift away from big sagebrush composition towards increased grass composition. To evaluate erosion risk associated with the treatments, we used two models to assess the impacts at different scales. We selected the Rangeland Hydrology and Erosion Model to investigate the hillslope scale, and a Gridded Surface Subsurface Hydrologic Analysis for the subwatershed scale. This two-model approach allowed us to utilize field-collected data to inform model construction and appraise how potential erosion varies with scale. The modeling assessment indicated little impact to erosion potential after tebuthiuron application at both scales. The short-term plant community response and erosion modeling serves as a point of initial assessment, and we will continue investigation until full herbicide effects have been realized. Through this short-term conservation practice efficacy assessment, we aim to improve treatment implementation strategies to increase the probability of achieving management goals.

Présentation (NMSU Library)

Aperçu document (ProQuest)