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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #322326

Title: Digging Deeper: Analyzing root traits to characterize juniper expansion into rangelands

item CHESUS, KELLY - Colorado State University
item OCHELTREE, TROY - Colorado State University
item Comas, Louise

Submitted to: Society for Range Management
Publication Type: Abstract Only
Publication Acceptance Date: 10/25/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: 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. To better explain juniper encroachment at the ecosystem level, we investigated root traits, functioning, and spatial patterns of water-use between juniper and sagebrush. 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.