CHANGES IN PLANT COVER AND ATTRIBUTES ACROSS A GRAZING GRADIENT IN NORTHEASTERN CHUBUT, ARGENTINA.

BÄR LAMAS, MI; LARREGUY, C; CARRERA, AL; BERTILLER, MB

San Juan

Otro; 2da. Reunión conjunta de las Sociedades de Biología de la República Argentina; 2011

In Patagonia, sheep grazing affects the architecture and dynamics of vegetation through the replacement of species with different morphologies and ecological strategies. We analyzed the variation induced by grazing on plant cover, specific leaf area (SLA) and the heights of dominant species of the northeastern Chubut (Argentina). In three sites across grazing gradient, we assessed the total and relative cover of shrubs and perennial grasses, species richness and species composition. At each site we measured the height and the SLA in 3 adult plants of each dominant species. The site with low grazing intensity had higher total plant cover and relative contribution of perennial grasses than the other sites. Species richness decreased with grazing intensity and the similarity in species composition was higher than 68% among sites. Plant height and SLA of each species did not vary among sites. In general, as grazing intensity increased the SLA of perennial grasses and the height of shrubs tended to decrease. Thus, grazing effect was mainly associated with changes in the relative abundance of different species and/or biological forms affecting the attributes at community level but without modifying them at the species level.