SCALE-DEPENDENT INTERACTION OF FIRE AND GRAZING ON COMMUNITY HETEROGENEITY IN TALLGRASS PRAIRIE

摘要: Natural disturbances affect spatial and temporal heterogeneity in plant communities, but effects vary depending on type of disturbance scale analysis. In this study, we examined the fire frequency (1-, 4-, 20-yr intervals) grazing by bison species composition tallgrass prairie communities. Compositional was estimated at 10-, 50-, 200-m2 scales. For each measurement scale, used average Euclidean Distance (ED) between samples within a year (2000) to measure all time steps (1993-2000) for sample heterogeneity. The main were independent. Spatial lowest annually burned sites highest infrequently (20-yr) Grazing reduced increased rate community change over decreased as scales, whereas had no effect any scale. interactive differed with At 10-m2 grassland less frequently areas. 50-m2 4-yr burns other frequencies. 10-m only 1- burn sites. Our results show that individual mesic are independent, these measurement. These patterns reflect homogenizing impact different frequency, intensity, patch vs.