Shrub and Tree Data for Plant Associations Across the Mojave/Great Basin Desert Transition of the Nevada Test Site, 1963--1975

摘要

The shrub, tree, and cactus vegetation of 59 selected study sites in eight drainage basins of the Nevada Test Site was documented in 1963, and again in 1975. Vegetation of the sites, which span the range of 3076 to 7425 ft elevation, is assigned to five plant associations, and intergrades, on the 25 Mojave Desert sites; eight associations on the 10 Great Basin Desert sites; and six associations, and ecotonal types, on the 24 sites of the desert transition. The data presented are for numbers of plants crossing the lines, mean height of plants, and calculated percentage cover of the ground. All data are summarized by site, species, and year for each of the vegetation categories, and for living and dead plants combined and dead plants only. Apparent from the data are increases in the numbers, height, and percentage cover on nearly all sites, and in essentially all species, during the 12-year period, and a decrease in the proportions of dead plants. Species composition or relative proportions of the species did not change. The increases appear to be directly related to rainfall during the time interval. It is concluded that in desert vegetation numbers and size of shrubs vary significantly with climatic fluctuations through time, and reflect especially the rainfall history of a given site at any point in time. (ERA citation 04:039607)