Professor, Emeritus Western Washington University Bellingham, West Virginia, United States
Abstract: In the Alvord Basin of southeastern Oregon, in the northern extreme of the Great Basin desert scrub, climate variation can be exemplified not only by contrasts in temperature and rainfall between La Nina and El Nino years, but by comparisons among consecutive years. Across a sixteen-year span in a single desert scrub locale, interannual variation in spring temperature, rainfall, aridity indices and evapotranspiration indices were used to predict contrasting outcomes among years in productivity in early summer at multiple trophic levels: 1) EVI as a proxy of primary productivity, 2) pitfall trap results for a) abundances of walkers such as ants and tenebrionid beetles, b) abundances of fliers and perchers such as flies, wasps and other beetles, and c) arthropods overall, which included both primary and secondary consumers. Interannual variation in arthropod abundances correlated closely with the climate variables. Variation in arthropod abundance also occurred within years at both mesohabitat and microhabitat scales. Bouts of extreme winter cold, however, also affected abundance of grasshoppers in summer. The effects of interannual variation in climate and long-term climate trends on this desert community are continuing and have been expanded; similar studies have begun in the Mojave and Sonoran deserts.
