Tree canopy cover and natural regeneration into strictly-protected forest areas: the MaB reserve of Montedimezzo (Isernia,Italy).

The ecological analysis and the analysis of mechanisms underlying the natural regeneration process into strictly protected forest areas, is basic to the understanding of ecosystem functioning and to estimate the recovery ability as a function of time and environmental changes. Aim of the paper is to analyze the spatial-temporal dynamics of tree species regeneration into mixed Turkey oak-common beech stands growing undisturbed since more than one half- century. The ability of first establishment and following growth of natural regeneration related to the ecological parameters, the structural features of standing crop and its development stages, are analyzed in detail. The study was carried out into two permanent monitoring plots (A) and (B) where two different tree species play the main functional role. In (A) common beech is dominant (Fagus sylvatica L.-elevation 1040 m a.s.l.); in (B) Turkey oak is prevailing (Quercus cerris L.-elevation 940 m a.s.l.). In each plot, the analysis of vertical stand structure, of natural regeneration pattern and ecological surveys (LAI, trasmittance, soil moisture content, canopy interception of rainfall) were undertaken by monthly surveys from May to October into 57 sub-plots each 1m2 wide over the period 2005-2007. Results highlighted that (B), Turkey oak prevailing, shows a more complex structure, a higher tree canopy thickness and the lack of gaps. The area shows therefore a lower trasmittance and a higher LAI value; throughfall and soil moisture content are also reduced as compared to (A). As for the natural regeneration pattern, further to a first stage when seedlings mortality is high, their survival rate is being kept high and steady over time in (A). A further mortality peak has been detected vice versa over the following summer season in (B). The different main tree species composition and radiation regime seem to be the basic reasons of the dynamics observed as for mortality and survival rates. The way of seedlings establishment points out that optimal ecological conditions are present for the production and germination of seeds as well, but that the limiting factor is the reduced radiation amount that reaches the forest floor.