INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
Grazing effects on biological soil crusts and their interaction with shrubs and grasses in an arid rangeland
SOLANA TABENI; GARIBOTTI, IRENE ADRIANA; CLARA PISSOLITO; JULIETA ARANIBAR
JOURNAL OF VEGETATION SCIENCE
WILEY-BLACKWELL PUBLISHING, INC
Lugar: Londres; Año: 2014 vol. 25 p. 1417 - 1425
AbstractQuestion:Biological soil crust (BSC) communities can be used in the identification and monitoring of degradation. A key question is how landscape scale livestockdisturbance and other local scale factors influence BSC communities. Wehypothesize that atthe landscape scale, increased grazing pressure would lead to a decreasingcover of BSC, but at the local scale biotic interactionsbetween BSC and vascular plants would modulate the influence of grazingon BSC.Methods: Spatially explicitsampling of vegetation composition and cover was conducted using point samplingmethods in digitalimages along two disturbancegradients in the central Monte Desert in Argentina. Results: The grazing gradient is the major determinant of changes in the structureof plant communities at the landscape scale. Approximately 1500 to 2000 m from watering point, there is a threshold in vegetationstructure associated with a nonlinear trend of the BSC, herbs, grasses andshrubs cover. Bivariatespatial patterns show attractionbetween BSC and shrubs in the vicinity of thesettlements, and repulsion between BSC and both grasses and litter in less disturbed sites. Conclusion: Grazing affectsBSC directly through trampling and indirectly by altering the vascular plantcommunities that interact with the BSC communities. Both these effects varyaccording to the spatial scale being considered. The results evidences that theunderstanding of livestock impact in structuring arid ecosystems requires anintegrated analysis of BSC and vascular plant communities at different spatialscales.