The significance of different indices for stand structure and diversity in forests

Data from the so-called Level II Plots which were established within the frame of the Pan-European Programme for Intensive and Continuos Monitoring of Forest Ecosystems were used to quantify stand structure and species diversity by means of different indices. The calculations presented are based on species composition, spatial pattern as well as diameter and height distribution. The data assessed are suitable to calculate different measures of structural diversity, if a mapping of the stands is carried out. A comparison of the different indices by means of correlation analysis shows that there exist only few and weak correlations between species diversity of different vegetation layers, and between plant species diversity and diversity of stand structure, while among all the indices of stand structure a correlation exists. More complex indices of stand diversity perform quite well in characterising the specific situation. Mountain forests are compared with forests from lower elevations. They show a tendency towards irregular stand structures. No correlation between the naturalness of tree species composition and the calculated diversity indices can be found within the sample.