Soil surface characteristics and emergence of big sagebrush seedlings

Abstract

The emergence of big sagebrush (Artemisia tridentata) seedlings from 5 gardens where both the seed source and the soils were reciprocated was investigated over a 5-year period in western Nevada. The sites where the study was conducted were located at the arid extremes for mountain (A. tridentata subsp. vareyana) and basin big sagebrush (A. tridentata subsp. tridentata) in the trans-Sierra Nevada area. Soils, sites, and seed sources differed significantly (P=0.01) in seedling emergence. The driest site, where it was difficult to obtain seedling emergence even on a year of above average precipitation, had a soil surface that was very conducive to the germination of seeds of big sagebrush when the seedbed was moved to garden locations with greater environmental potential. Seedbed quality differed markedly among sites with soil derived from decomposing granite versus metavolcanic sources. Big sagebrush seeds were buried in soils derived from granite through a winnowing action. Seeds from a non-granitic soil site were also adapted, apparently through size and shape, to this winnowing self-burial. The dominant microenvironmental factors contributing to seedling emergence tended to be site and seed source specific. Microtopography in the fall, when seeds were dispersed, and seasonal precipitation were dominant factors controlling the emergence of big sagebrush seedlings.