Plant Community Dynamics in the Great Basin: Long-Term and Broad Scale Change in Wooded Shrublands

Abstract

Expansion of native pinyon-juniper (Pinus monophylla-Juniperus osteosperma) woodlands can decrease shrub and herbaceous cover in the Intermountain West, affecting habitat quality and biodiversity. Changes in the range and cover of other plant communities, including forbs and invasive grasses, are also occurring. Removing woodlands in former sagebrush ecosystems has a long management history, with interest in understory plant community responses. We revisited a restoration site in western Nevada, 32 years after tree thinning treatments had occurred, and conducted vegetation measurements within historic treatment plots. Our findings suggest tree thinning and removal can increase shrub and perennial grass cover, but tree recolonization over the long-term is possible. We also used vegetation data repeatedly collected at unmanipulated monitoring plots to calculate change in foliar and litter cover during 2011-2017. Increases in pinyon-juniper dominance influenced decreases in foliar cover of shrubs and sage-grouse preferred forbs, and litter cover of all types increased significantly.