Plant species dominance and disturbance at a grassland-shrubland ecotone

TitlePlant species dominance and disturbance at a grassland-shrubland ecotone
Publication TypeConference Paper
Year of Publication2000
AuthorsPeters DC
Conference Name85th Annual Meeting, Ecological Society of America
Date PublishedAugust 6-10, 200
Conference LocationSnowbird, UT
ARIS Log Number110116
Keywordsdisturbance, ECOTONE, grassland, plant species dominance, Sevilleta LTER, shrubland
AbstractThe objective of this study was to evaluate the role of presence and identity of dominant species on vegetation patterns at a shortgrass steppe- Chihuahuan desert ecotone. Species removals were conducted: (1) to identify new dominant species and assemblages after the current dominant is removed, and (2) to determine if dominant species with different life history traits shave different legacy effects on recovery of other species through time. This study was conducted at the Sevilleta LTER in central New Mexico where communities may be dominated or codominated by one of two perennial grasses (blue grama, black grama) and one shrub (creosotebush). Within each community, all plants of the dominant species were removed from within 5 3m x 4m plots in 1995, and have been removed annually since that time. Five control plots were also located at each site. Cover and density by species have been estimated annually since 1995. 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 forbs whereas removal of black grama promoted recovery by perennial grasses. 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. Legacy effects were most important in the first few years after removals were initiated. These results indicate that removal of dominant species by disturbances have dramatic effects on vegetation patterns that may alter the landscape mosaic at this arid-semiarid ecotone.