Are the effects of the overstory on herb and shrub layers important in forest habitat monitoring? The case of Quercus suber woodlands. Communication VIII.

Our study has tested the effects of overstory data (structural data such as cover, average height and stand basal area of tree species) on the shrub and herb layers to check the importance of tree structure and composition for forest habitat monitoring. The research was carried out in the EU Habitat “Quercus suber forests” (code 9330), that includes woods characterized by dominance of the cork oak (Quercus suber L.), differentiated respect to the Q. ilex forests by a lesser tree coverage that leaves ample space for herbaceous and shrubby species. The results underline the key role of substrate in driving understory composition in the Q. suber woods, showing a statistically significant difference in species composition between the forests growing in the two types of substrate.