Get reliable rangeland science

In the Great Basin the most effective defense against annual grass invasion may be targeted restoration of competitive herbaceous plants in existing stands of sagebrush (Artemisia tridentata ssp. wyomingensis), rather than areas where sagebrush has been removed due to fire or other disturbances. This type of approach requires an understanding of where, within a mosaic of canopy and inter-canopy gap microsites, restoration actions will lead to maximum plant establishment success. We therefore examined restoration planting success, from seeds and seedlings, with respect to canopy and gap microsites across three sites in the Great Basin. We targeted two bunchgrasses, bottlebrush squirreltail (Elymus elymoides) and bluebunch wheatgrass (Pseudoroegeneria spicata). For both species, we found that restoration plantings from seed showed high (61-74%) establishment success across both canopy and interspace microsites after seven months, but declined markedly after the first year (3-11%). Restoration plantings from seedlings also showed high (81-99%) initial establishment rates (after 7 months), though establishment of E. elymoides, appeared to be greater in interspace than canopy microsites at the driest site. Interestingly, this is in contrast to distributions of mature, naturally-established E. elymoides plants which occur in higher densities in canopy microsites, particularly at drier sites. Together these results illustrate how plant responses to canopy vs. gap microsites may differ according to species, life stage and both short- and long-term moisture conditions. Ultimately our results can be used to help guide restoration in sagebrush-dominated systems.