PARENT SESSION
Contributed Oral Session 129: Biodiversity: Disturbance; Landscapes; Heterogeneity
Thursday, August 11, 1:30 PM - 5:00 PM, Meeting Room 513 E, Level 5, Palais des congrès de Montréal
Effects of spatial heterogeneity on native and non-native plant species richness in Rocky Mountain National Park, Colorado, USA.
Kumar, Sunil*,1, Stohlgren, Thomas2, Chong, Geneva2, 1 Natural Resource Ecology Laboratory, Fort Collins, Colorado, USA2 USGS Fort Collins Science Center, Fort Collins, Colorado, USA
ABSTRACT- Spatial heterogeneity may influence species diversity patterns, and spatial and temporal changes in spatial heterogeneity due to biotic or abiotic characteristics may alter the species distribution patterns. We examined the role of spatial heterogeneity in determining the distribution of native and non-native plant species richness in the central 80,000 ha portion of the Rocky Mountain National Park, Colorado, USA. The spatial heterogeneity was characterized using landscape metrics (e.g., patch size coefficient of variation, fractal dimension, and Simpson′s diversity index), environmental/topographical variables (elevation, slope, aspect), and soil variables (nitrogen, sand, and clay). FRAGSTATS landscape analysis program quantified landscape metrics at six spatial scales within varying radii (120, 240, 480, 960, and 1920 m). Multiple linear regression models with Akaike′s Information Criteria (AIC) were used to select best models from the set of candidate models. At the landscape level, the greatest amount of variation explained occurred at the 240-m scale. The models at successively smaller and larger spatial scales explained relatively less variation. Environmental/topographical and soil variables explained 16% of the variation in native species richness (F5, 772 = 30.81, P < 0.0001, AIC = 2282.25) and 21% of the variation in non-native species richness (F6, 771 = 34.34, P < 0.0001, AIC = -2521.40). However, when these variables were coupled with landscape metrics, the amount of variation explained was significantly improved to 25% of the variation in native species richness (F7, 770 = 37.30, P < 0.0001, AIC = 2200.65), and 35% of the variation in non-native species richness (F9, 768 = 47.15, P < 0.0001, AIC = -2673.39). The effect of spatial heterogeneity on the distribution of native and non-native species richness is highly scale dependent, and the landscape metrics are needed in native and non-native species richness models.
Key words: spatial heterogeneity, native and non-native species richness, FRAGSTATS, Rocky Mountains