Effects of small patchy distrubances on plant species diversity at a semiarid grassland ecotone

Title	Effects of small patchy distrubances on plant species diversity at a semiarid grassland ecotone
Publication Type	Conference Paper
Year of Publication	2000
Authors	Kroel-Dulay G., Hochstrasser T., Peters DC
Conference Name	85th Annual Meeting, Ecological Society of America
Date Published	August 6-10, 200
Conference Location	Snowbird, UT
ARIS Log Number	116307
Keywords	grassland, kangaroo rats, patchy disturbances, semiarid-arid, species diversity
Abstract	Our objective was to evaluate the effects of patchy disturbances created by kangaroo rats on species diversity and composition at a semiarid-arid grassland ecotone. Our study was conducted at the Sevilleta LTER in New Mexico, where a grassland dominated by Bouteloua gracilis, a shortgrass steppe species, and a grassland dominated by B. eriopoda, a Chihuahuan Desert species, meet to form patches across the landscape. Four 0.4 ha plots were sampled for vegetation within a 7m x 7m grid in each grassland type. Kangaroo rat mounds were also mapped and sampled in 4 areas of 1.6 ha in each grassland type. The landscape scale abundance of many subordinate species was increased significantly by populations occurring on kangaroo rat mounds in both grassland types. Dominant plants on mounds in the B. eriopoda type were also abundant in off-mound areas whereas dominant plants on mounds in the B. gracilis type were not as abundant off-mound. These results indicate that the presence of mounds in B. gracilis dominated grasslands creates islands of plant communities that are distinct from the rest of the grassland. Therefore, the occurrence of certain plant species in this grassland may be intimately associated with the disturbance regime at this ecotone.