Preliminary Assessment of a Riparian Forest Along the Washita River in Western Oklahoma

Abstract

Trees in semi-arid grasslands of the Great Plains are often restricted to riparian corridors due to higher water needs. This is also coupled with agricultural practices that often remove trees for various needs. As such, riparian forests could be legacies of land-use patterns and climate change in an environment that can experience frequent droughts. We investigated a riparian corridor along the Washita River and adjacent agricultural landscape in Custer County, Oklahoma in order to relate tree diversity, tree ages, radial growth patterns, and tree establishment patterns to land-use history and climate. Transects were established at increasing distances from the river. Increment cores were collected from trees to estimate tree ages, radial growth patterns, and establishment patterns. One hundred and ten cores were collected from seven species. The largest cored tree was bur oak (Quercus macrocarpa Michx.) (diameter 138.7 cm) while the smallest was western soapberry (Sapindus saponaria L. var drummondii (Hook & Arn.) L.D. Benson). The oldest tree was bur oak (149 y.o.) while the oldest tree found for three species was <20 y.o. Preliminary analysis suggests that the oldest trees were along the transect closest to the Washita River and the youngest trees were located along the transect furthest from the river within an agricultural field. We are in the process of expanding this research to another location and assessing spatial patterns of tree establishment.