Beskydy 2012, 5, 163-172
Spatio-temporal structure of natural forest: A structural index approach
The submitted paper deals with the analysis of stand structure of mixed species natural forest located in the Carpathians, Middle Europe. In order to evaluation of structural diversity we chose the combination of distance independent and nearest-neighbor indices. Following structural indices were calculated: Shanon-Weaver index (S-W), diameter differentiation index (Td), Gigi coefficient (G), mingling index (DMi) and Clark Evans index (CEd). The permanent research plot with area of 2.5ha was established in National Naure Reserve Hrončecký grúň and subdivided into 25×25m subplots. The combination of mentioned indices was calculated for each subplot separately. Regarding the diameter heterogeneity, the most part of analyzed structures showed the moderate level of tree size differentiation (S-W value 0.393±0.074). The presence of high number of juvenile individuals which already reached the diameter category “above 2cm” did not significantly affect the diameter variation of investigated stand. On the other hand, a massive establishment of subsequent generation led to creation of spatial structure characteristic by high level of vertical differentiation (Gini coefficient 0.47 in the structure characterized as the breakdown with successive generation). High climax species richness was confirmed by calculated values of DMi index (maximum relative presence in the category from 0.3 to 0.4). Each tree was surrounded by two and more different species individuals. Analysis discovers the negative developmental shift in the DMi values towards to less differentiated structures. Regarding the horizontal distribution the analysis of CEd values indicated that investigated natural forest can reveal a random distribution of individuals regardless of developmental stage.
