SHIFTING ELEVATIONAL DISTRIBUTIONS OF THREE SUBALPINE AND ALPINE PLANT SPECIES IN THE WHITE MOUNTAINS, CALIFORNIA

This study investigates recent changes in distribution of dwarf sagebrush (Artesmia arbuscula), bristlecone pine (Pinus longaeva), and limber pine (P. flexilis) at their uppermost limits in the White Mountains, eastern California. Dwarf sagebrush was examined by ground survey around Mt. Barcroft in the central White Mountains. Changes in the distributions of limber and bristlecone pines, the subalpine treeline species in the White Mountains, were examined on Sage Hen Flat and along upper Crooked Creek by comparisons of airphotos from 1947 and 2005. Anthropogenic climate change is suspected to be having an effect on and changing the elevational distributions of these three species. The dwarf sagebrush field survey located individual plants around Mt. Barcroft and compared the numbers, sizes, and distributions to an identical survey conducted in 2005-06. The analysis showed that more sagebrush were found at higher elevations in 2010 compared to the 2005-06 survey, but the size distribution has not changed significantly. The trees were surveyed over a larger area in the subalpine woodland centered on Sage Hen Flat by comparing airphotos taken over the area from 1947 and 2005. The airphoto survey analysis showed that ≈85% of the new pine growth is ≥ 50 feet from than the established tree line in 1947. These trees are expanding in all directions – upslope, around aspects, and downvalley, depending on local topographic and microclimatic conditions. This research implies that climate change is having an effect on the elevational distributions of these ecosystem-defining alpine and subalpine plants. The presentation of this work will present maps showing the shifting distributions of sagebrush on Mt. Barcroft and subalpine trees on and around Sage Hen Flat in the White Mountains, CA.