Shading effects of trees on the understorey species composition and floristic diversity

The objective of this study was to evaluate the shading effects of trees on the understorey species composition and floristic diversity. The study was conducted in Laggadia, Pella prefecture, in beech (Fagus sylvatica L.) forested areas where shading levels were 95% and 75%, measured by a Licor quantum sensor. The experimental area was not grazed. During June 2005 in every forested area, 3 transects were established with different shading level. For comparative purposes 3 transects were established in an adjacent open grassland (shading level 0%). Species composition was measured and floristic diversity indexes were determined. The understorey species composition was significantly altered. The open grassland was dominated by the perennial grasses Dactylis glomerata and Poa pratensis, the 75% shading level forested area was dominated by the species Bromus benekenii and Rubus sanctus, while the 95% shading level forested area was dominated by the species Rubus sanctus and Pteridium aquilinum. The increase of the shading level contributed to the decrease of the floristic diversity as it was higher in the open grassland compared to the  95% shading level forested area, according to the determined indexes.