|Hochstrasser, T - COLORADO STATE UNIVERSITY|
Submitted to: Ecological Society of America Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 8, 1999
Publication Date: August 8, 1999
Citation: HOCHSTRASSER, T., PETERS, D.C. THE INFLUENCE OF DOMINANT PLANTS ON WATER DYNAMICS AT A SEMIARID GRASSLAND-SHRUBLAND ECOTONE: IMPLICATIONS FOR THE RECRUITMENT OF LARREA TRIDENTATA. 84TH ANNUAL MEETING, ECOLOGICAL SOCIETY OF AMERICA. 1999. V. 80. ABSTRACT P. 109. Technical Abstract: Dominant plants are defining vegetation structure in semi-arid ecosystems. Microsites around the dominant grass (Bouteloua eriopoda) and the dominant shrub (Larrea tridentata) support different species diversity of subdominant plants at a grassland- shrubland ecotone at the Sevilleta LTER. We suggest that these two dominants differ in their influence on soilwater dynamics, which, together with soil texture differences, contributes to differential recruitment in those microsites. Particularly important is the recruitment of dominants. Using a daily time-step soilwater model (SOILWAT) we evaluated the influence of the different conditions in those microsites on the establishment of L. tridentata. We were interested in the influence of competition, shading, and soil texture. We found that even though mature B. eriopoda individuals were effective competitors for water during the growing season, recruitment of L. tridentata could occur around the grass at the end of the growing season, when the grass was becoming dormant. Thi had the effect that the probability of recruitment was higher in microsites around the grass dominant than in microsites around the shrub dominant. This contrasts with our finding from the field that germination of L. tridentata was higher around shrubs. Therefore, the observed germination pattern was not related to water availability as simulated, but was related to different factors, e.g. seed availability. These results further our understanding of the dynamics of dominants at this grassland- shrubland ecotone and, therefore, help to interpret vegetation structure.