Canopy‐Coverage of the Desert Shrub Vegetation Mosaic of the Nevada Test Site

Abstract

Canopy—coverage of shrubs and perennial herbs was determined on 44 relatively undistributed sites scattered throughout the vegetation mosaic covering valleys in southcentral Nevada. The dominant shrubs were Larrea divaricata, Grayia spinosa, Lycium andersonii, Coleogyne ramosissima, atriplex confertifolia, Artemisia tridentata, and A. arbuscula subsp. nova. Perennial herbs contributed little to canopy—coverage. The perennial herbs most frequently encountered were Oryzopsis hymenoides and Stipa speciosa. In the spring of 1960, on 34 of the same sites, the canopy—cover of annual herbs was also determined. Sites dominated by Larrea shrubs had more annual species and also the greatest amount of annual cover. Chaenactis stevioides was ubiquitous and often the dominant annual encountered throughout the vegetation mosaic. Other important annuals was Mentzelia veatchiana, Eriogonum maculatum, Eriophyllum pringlei, Bromus rubens, Cryptantha nevadenseis, C. circumscissa, and Amsinckia tessellata.