Landscape consequences of small-scale disturbances at a grassland-shrubland ecotone

Title	Landscape consequences of small-scale disturbances at a grassland-shrubland ecotone
Publication Type	Conference Paper
Year of Publication	2001
Authors	Peters DC
Conference Name	16th Annual Symposium, US-International Association of Landscape Ecology
Date Published	April 25-29, 200
Conference Location	Tempe, AZ
ARIS Log Number	141499
Abstract	The objective of this study was to evaluate the role of small-scale disturbances within different patch types to landscape-scale patterns in species composition and dominance at a shortgrass steppe-Chihuahuan Desert ecotone. Species removals were conducted at the Sevilleta LTER in central New Mexico within five different patch types where communities are dominated or codominated by one of two perennial grasses (blue grama, black grama) and one shrub (creosotebush). Within each patch type, all plants of the dominant species were removed from five 3m x 4m plots starting in 1995; five control plots were also located within each patch type. Cover and density by species have been estimated annually. Similarity indices were used to compare patch-scale patterns in species composition with the landscape mosaic. Annuals dominated all removal plots one year after removals were initiated. Subsequent recovery patterns depended upon the dominant species removed. Blue grama removal resulted in establishment and growth of perennial grasses, whereas removal of black grama promoted recovery by perennial forbs. Removal of creosotebush in mixed communities with black grama resulted in recovery by perennial forbs, grasses, and shrubs whereas removal of this species in shrub-dominated communities resulted in little change in the vegetation. These results indicate that mortality of dominant species by small-scale disturbances has dramatic effects on vegetation patterns that may alter the landscape mosaic at this arid-semiarid ecotone.