ROOT DISTRIBUTION PATTERNS OF COMMON CURLYMESQUITE AND SIDEOATS GRAMAON 2 TEXAS RANGELAND SITES

Root distribution was determined in terms of biomass, length and root hairs/mm root for populations of sideoats grama (Bouteloua curtispendu la) and common curlymesquite (Hilaria belangen) in the Edwards Plateau and Rolling Plains resource regions of Texas. There were few signific ant differences in incremental (100 mm increments to a depth of 1 m) o r total root biomass or root length between species at either site. Si deoats grama had a significantly greater root hair density than curlym esquite from the soil surface to a depth of 600 mm at both sites. Root hair density was greatest, for both species, at the Rolling Plains si te. Greater root hair density of sideoats grama may be an adaptation a llowing greater and more rapid access to water, as suggested by concur rent studies of water use within lysimeters with sideoats grama or cur lymesquite. This suggests that greater root hair density of sideoats g rama confers an adaptive advantage with respect to soil water use comp ared to curlymesquite, and may be partially responsible for its region al dominance in advanced succession communities.