Wildlife Impacts to Big Sagebrush on Reclaimed Mined Lands

Abstract

Wildlife browsing of Artemisia tridentata ssp. wyomingensis (big sagebrush) on reclaimed coal mined land threatens long-term, sustainable reclamation success. A wildlife-proof exclosure was constructed in 2001 on a 10-year old A. tridentata ssp. wyomingensis reestablishment research site at North Antelope Coal mine in northeastern Wyoming to assess wildlife browsing impacts. Artemisia tridentata ssp. wyomingensis survival, growth, and plant community attributes (species richness, canopy cover, and diversity) were evaluated inside and outside the exclosure, across the original grass seeding rate treatments (0, 16, 32 kg PLS ha−1). Long-term A. tridentata ssp. wyomingensis density decreased across all seeding rates from 1994 to 2002. Higher A. tridentata density, leader (shoot) growth, and canopy cover, along with lower mortality, occurred inside the exclosure across all seeding rates. Lower winter use, higher survival, and lower mortality of A. tridentata ssp. wyomingensis in the 32 compared to the 0 and 16 kg PLS ha−1 seeding rates suggest a beneficial relationship between A. tridentata ssp. wyomingensis survival and higher grass seeding rate. Approximately 33% mortality of marked A. tridentata ssp. wyomingensis plants occurred outside the exclosure. Lepus townsendii campanius (white-tailed jackrabbit), L. californicus melanotis (black-tailed jackrabbit), and Sylvilagus audubonii baileyi (cottontail rabbit) were identified as primary browsers of A. tridentata. Plant species richness, cover, and diversity decreased from 2001 to 2002, probably due to below average precipitation during the study. Defoliation of A. tridentata ssp. wyomingensis was severe, indicating the magnitude of impact from browsing wildlife. Post mining wildlife management and habitat manipulation on adjacent rangeland is suggested to ensure successful reclamation of coal mined lands.