Theme 1-2: Rangeland/Grassland Ecology--Poster Sessions
Description
Woody encroachment of mesquite (Prosopis) and acacia (Acacia) species into grasslands has widespread and ongoing impacts on grassland ecosystems. Changes in the herbaceous layer are associated with changes in the canopy cover of these sparse-canopied species, which do not exclude the herbaceous component, but often change species composition under the canopy relative to surrounding open areas. These effects are often differential based on productivity of the site and herbaceous species composition of the grassland. Here we investigated landscape-scale changes in the herbaceous composition resulting from changes in canopy cover of honey mesquite (Prosopis glandulosa) within woody-encroached areas of Texas, U.S.A. Mesquite canopy percent changes were determined from aerial photographs and related to field-based measurements of the herbaceous component. We then related our findings to similar studies in the literature within different environments to assess similarities and differences among the impacts on the herbaceous component across a range of conditions. We utilized herbaceous layer functional groups to make these comparisons across different sites. Finally, we evaluated these changes in herbaceous composition to rates of woody encroachment to assess temporal changes across the landscape and possible impacts from restoration. We found that changes in the herbaceous layer were dependent on length of time of woody encroachment, percent woody cover, and site productivity.
Included in
Landscape-Level Impacts of Mesquite Canopy Cover on Herbaceous Species Composition
Woody encroachment of mesquite (Prosopis) and acacia (Acacia) species into grasslands has widespread and ongoing impacts on grassland ecosystems. Changes in the herbaceous layer are associated with changes in the canopy cover of these sparse-canopied species, which do not exclude the herbaceous component, but often change species composition under the canopy relative to surrounding open areas. These effects are often differential based on productivity of the site and herbaceous species composition of the grassland. Here we investigated landscape-scale changes in the herbaceous composition resulting from changes in canopy cover of honey mesquite (Prosopis glandulosa) within woody-encroached areas of Texas, U.S.A. Mesquite canopy percent changes were determined from aerial photographs and related to field-based measurements of the herbaceous component. We then related our findings to similar studies in the literature within different environments to assess similarities and differences among the impacts on the herbaceous component across a range of conditions. We utilized herbaceous layer functional groups to make these comparisons across different sites. Finally, we evaluated these changes in herbaceous composition to rates of woody encroachment to assess temporal changes across the landscape and possible impacts from restoration. We found that changes in the herbaceous layer were dependent on length of time of woody encroachment, percent woody cover, and site productivity.
