Plant Community Response to Mowing in Wyoming Big Sagebrush Habitat in Nevada
AdvisorSwanson, Sherman R.
Natural Resources and Environmental Science
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Thousands of acres of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) habitat have been mowed throughout Nevada to create fuelbreaks for wildfire control, enhance resilience and resistance to invasive plant species, increase perennial herbaceous understory, and improve wildlife habitat. To improve our understanding of how these plant communities respond to mowing and whether treatment goals are being met, an observational study of paired mowed and unmowed locations was conducted between 2010 and 2015 across the geographic extent of mowed Wyoming big sagebrush in Nevada. In 2015, foliar and ground cover, perennial herbaceous density, and soil profile data were collected at 32 locations within 16 individual mow projects of different ages. Wilcoxon signed rank tests indicated significantly different mean cover values of ground cover, functional groups and individual species between treated and untreated locations. Bare ground (p < 0.01), moss (p < 0.01), cryptogam (p = 0.01), total foliar cover (p < 0.01), non resprouting shrub (p < 0.01), Poa secunda (p = 0.01) and Phlox sp. (p = 0.04) cover were lower in mowed locations. Litter (p < 0.01), tall perennial bunchgrass (p = 0.02), Bromus tectorum (p = 0.08) and Elymus elymoides (p = 0.01) cover were greater in mowed locations. Median density values of tall perennial bunchgrasses (p = 0.01), Sphaeralcea sp. (p = 0.04), and Agropyron cristatum (p = 0.08) were greater in mowed locations, while Linanthus pungens density (p = 0.02) was lower. Generalized linear models examining the influence of abiotic variables on herbaceous perennial response showed that greater amounts of precipitation in March through June following treatment were correlated with greater increases in perennial herbaceous cover (p < 0.01). An increasing percentage of clay in the soil A horizon was correlated with greater perennial herbaceous density following treatment (p = 0.02). Precipitation during July through September in the year following treatment was correlated with declines in both perennial herbaceous cover (p < .01) and density (p < .05). These results indicate variable responses to mowing in Nevada.