Shrub densities on pre-1985 reclaimed mine lands in Wyoming

The reestablishment of native shrubs is part of the mandate under which min ing companies extract mineral resources in Wyoming and other western states . Post-mining shrub density and species mixtures have been topics debated b y various mine reclamation stake holders. By law, coal-mined lands in Wyomi ng must now meet a post-mining shrub density of 1 shrub/m(2) on 20% of the affected area. To better understand the long-term results of shrub reclamat ion methods, we measured shrub density by species in 14 pre-1985 seedings a t eight mines in three geographic regions of Wyoming. The sites studied wer e selected as Atriplex canescens (Pursh) Nutt. (fourwing saltbush) and gras s or as Artemisia tridentata Nutt. ssp. wyomingenesis (Beetle and Young) (W yoming big sagebrush), fourwing saltbush, and grass post-mining communities . Shrub density and composition varied by site but typically reflected the seed mixtures used. Seedings that used a diversity of shrub species general ly had greater 1994 shrub densities. Seeding rates between 60 and 1000 shru b seeds/m(2) had a positive, linear relationship with shrub density up to 0 .6 shrubs/m(2) when sagebrush was part of the shrub seed mixture. We conclu de that the likelihood of meeting the shrub standard can be enhanced by see ding diverse shrub mixtures at high seeding rates.