Species composition changes after three years of goat grazing exclosure in the Tenerife pastures

Pastures in the Canary Islands are of modest size, which may be one of the reasons they have not attracted researchers’ interest. They very likely represent the richest plant community of the archipelago, something that can be attributed to their history, management, and dynamics. Pastures of Tenerife Island (Canary Islands) are almost wholly restricted to the Teno peninsula. These patches of pastures are small in size (from a few ha to less than 1000 ha, less than 1% of the area of Tenerife) and fragmented due to the topography of the island. In the Teno plateau the number of goats has increased by 70% in the past ten years. In this area we exclosure eight 100 m² plots and located near to each one a control plot. We sampled during three years (2005, 2006 and 2007) species composition in the plots and visually estimated the species cover individually.
The results of DCA analysis revealed that changes in species composition are occurring but they are not as important as the variability of each plot in different location. At this moment we can conclude that species composition is more related with the local heterogeneity that with the experimental exclosure. However, in some plots, changes in species composition are occurring, favoring the exclusure shrubs species with respect forbs and graminoids species.