HR: 1340h
AN: U53A-0708    [Abstracts]
TI: Reconstructing a Past Climate Using Current Multi-species' Climate Spaces
AU: * Westfall, R D
EM: bwestfall@fs.fed.us
AF: Sierra Nevada Research Center USDA Forest Service PSW Research Station, PO Box 245, Berkeley, CA 94701
AU: Millar, C I
EM: cmillar@fs.fed.us
AF: Sierra Nevada Research Center USDA Forest Service PSW Research Station, PO Box 245, Berkeley, CA 94701
AB: We present an analysis of a ghost forest on WhiteWing Mt at 3000 m in the eastern Sierra Nevada, southeast of Yosemite NP. Killed by a volcanic eruption about 650 years ago, the deadwood on WhiteWing dates by standard tree-ring analysis to 800-1330 CE, during the Medieval Warm Anomaly. Individual stems have been identified by wood anatomical characteristics as Pinus albicualis, P. monticola, P. jeffreyi, P. contorta, P. lambertiana, and Tsuga mertensiana. With the exception of P. albicualis, which is currently in krummholz form at this elevation, the other species are 200 m or more lower in elevation. One, P. lambertiana, is west of the Sierran crest and 600 m lower in elevation. Assuming that climatic conditions on Whitewing during this period were mutually compatible with all species, we reconstruct this climate by the intersection of the current climatic spaces of these species. We did this by first generating individual species' ranges in the Sierran ecoregions through selecting vegetation GIS polygons from the California Gap Analysis database (UCSB) that contain the individual species. Climatic spaces for each species were generated by the GIS intersection of its polygons with 4 km gridded polygons from PRISM climatic estimates (OSU); this was done for annual, January, and July maximum and minimum temperature, and precipitation, merged together for each species. Climatic intersections of the species were generated from the misclassified polygons of a discriminant analysis of species by the climatic data. The average data from these misclassified polygons suggest that the climate on WhiteWing during the existence of this forest community was 230 mm, 1oC, and 3oC greater than present in precipitation, and maximum and minimum temperature, respectively.
DE: 3344 Paleoclimatology
DE: 1655 Water cycles (1836)
DE: 1851 Plant ecology
DE: 1620 Climate dynamics (3309)
DE: 0400 Biogeosciences
SC: Union [U]
MN: 2004 AGU Fall Meeting