Analysis of structure and effects of wild herbivore overgrazing on Kouri forest, Magnesia (Natura 2000 site)

A study concerning the forest structure and grazing effects of three introduced wild herbivores on a plain oak forest in Kouri, Almyros, Magnesia was conducted. The introduced species were: mouflon (Ovis ammon), fallow deer (Dama dama) and roe deer (Capreolus capreolus). The forest overstorey consisted mainly of Quercus pubescens whereas Quercus ithaburensis subsp. macrolepis was present. The grazed part of the forest, 70 ha, is fenced and the ungrazed one covers an area of 30 Ha. Herbivore density reached at 157 animals per 100 ha and after a reduction dropped to 74 animals per 100 ha. In the ungrazed part oak trees had greater diameter and crown size than those in the grazed part. Tree density was higher in the grazed part, whereas the mean tree height was similar in both parts. In the ungrazed part the trees were more vigorous and the regeneration rate was higher than in the grazed part. In the understorey Asphodelus microcarpus and Stipa bromoides were the dominant species. Heavy grazing resulted in expansion of these two species. In order to avoid further deterioration of the forest, removal of all animals or reduction of stocking intensity at the carrying capacity level and -*specified management actions promoting the oak regeneration were proposed.