Sagebrush steppe vegetation monitoring in Lake Roosevelt National Recreation Area: 2011 annual report

Yeo, Jeffrey; Rodhouse, Thomas

Lake Roosevelt National Recreation Area (LARO) is one of 5 parks within the Upper Columbia Basin Inventory and Monitoring Network (UCBN) area that contains sagebrush steppe ecosystems. Five monitoring sites within Lake Roosevelt National Recreation Area, each containing 50 or 55 plots, were sampled in early June 2011 following methodologies described in Yeo et al. (2009). Three of the 5 sites are grazed by cattle annually in spring and in fall, and 1 site contains the Spring Canyon campground and boat launch. Cover of exposed soil, sagebrush, other shrubs, perennial native grasses, perennial persistent forbs, other native forbs, non-native invasive forbs, and non-native invasive grasses were estimated in randomly-located 1-m² plots. The weather in spring and early summer 2011 were unusually wet and mild. Cheatgrass (Bromus tectorum), a non-native, invasive annual grass, was ubiquitous across all 5 sites, and was the most frequently encountered plant at all 5 sites. Other non-native annual grasses, Japanese brome (Bromus japonicus) and bulbous bluegrass (Poa bulbosa), also were occasionally abundant. Dalmatian toadflax (Linaria dalmatica), an invasive noxious forb, was common at 1 site and present at other sites as were knapweeds (Centaurea spp.; also noxious, invasive forbs). Plots depicting sagebrush steppe in good condition were sparsely scattered within the 5 monitoring units indicating (1) the very limited extent of vegetation in good condition, and (2) the small patch sizes of good condition habitat. There were isolated patches of vegetation in several of the monitoring sites in which native bunchgrasses such as bluebunch wheatgrass (Pseudoroegneria spicata) and Idaho fescue (Festuca idahoensis) were dominant. Three of the 5 monitoring sites were sampled in 2009 and selected variables were compared between the 2 sampling years. Differences in cover estimates between the 2 sample years were few, and the wet, mild spring and early summer weather of 2011 likely contributed to higher cover of annuals with resultant lower estimates of exposed soil cover compared to vegetative conditions experienced in the drier and warmer weather of 2009.

Sagebrush steppe vegetation monitoring in Lake Roosevelt National Recreation Area: 2011 annual report

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