Document: THO-3-9-8

Exotic species and biodiversity in mountain forests.

STOHLGREN, T.J.* ^1,2,3, J.E.KEELEY ^3,4 and D.M.GRABER ⁴

Midcontinent Ecological Science Center, Fort Collins, CO USA ¹
Colorado State University, Fort Collins, CO USA ²
US Geological Survey, Fort Collins, CO USA ³
National Park Service, Three Rivers, CA USA ⁴

Abstract:
Vegetation surveys in Rocky Mountain National Park, Colorado, and Sequoia and Kings Canyon National Park, California, U.S.A. show similar, alarming patterns in the invasion of exotic plant species. In Rocky Mountain NP, 42 1000-m² plots on 14 vegetation transects revealed that both native and exotic species richness were negatively correlated with elevation and positively correlated with under-canopy solar radiation (P < 0.001; R² = 0.40 and R² = 0.33, respectively). Data from 680 0.1-ha plots in Sequoia and Kings Canyon NP also showed that exotic species richness declined exponentially with increasing elevation (y = 107e^-0.0022; r² = 0.72). In the Rocky Mountains and Sierra Nevada, many exotic annual species have not yet gained dominance in high-elevation, perennial-dominated meadows. However, managers of national parks and natural areas now face a formidable challenge because hot-spots of native plant diversity, especially riparian zones, low-elevation wet meadows, open woodlands, and rare habitats are being heavily invaded by exotic plant species.

Keywords: exotic plant species, biodiversity, mountains, forests

This abstract is being presented at: 9:30 AM in session:
Symposium # 2: Stressors in Western Mountain Ecosystems: Detecting Change and Its Consequences.