Juniper expansion into sagebrush communities is a widespread phenomenon occurring across large regions of the western U.S. over the past century. The primary concerns of juniper encroachment are the decrease in forage for wildlife and livestock and potential changes in water quantity. Management of this phenomenon has therefore focused on the removal and reduction of juniper trees from areas of active encroachment. Fire suppression and increased grazing activity are commonly considered as the primary drivers of juniper expansion but they do not explain all instances of expansion. In order to develop a complete explanation for the success of juniper we investigated the competitive abilities of juniper and sagebrush based on root traits. Given the water-limited systems that juniper and sagebrush commonly inhabit, analyzing the spatial pattern of water-use between these species may provide a better understanding of juniper encroachment at the ecosystem level. Because encroachment relies upon the successful establishment and survival of juniper seedlings to maturity, we designed our study to include measurements from different age classes (seedling, saplings, and adults). Five randomly selected pairs of juniper and a neighboring sage were selected for each age class. To assess their ability to access water we collected 3 soil cores from each pair to quantify depth-resolved differences in root traits. We also extracted stem and soil water from these pairs in June - August for water isotope analysis to quantify the vertical profile of soil water uptake. We will discuss species differences in specific root length, number of root tips, and isotopic signatures and their implications for the juniper encroachment phenomenon.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.