Article

In this study we consider the use of ecoindicators to explain the complex relationships between vegetation and humus in forest ecosystem from all the Italian Peninsula. In particular we concentrate the study on the rarely applied indicators of Rogister’s: RxN and R/N, that would represent the humus quality of soil. They are derived from the Ellenberg Indicator Values (EIV), R and N (R = Reaction, N = Nutrients). The aim of the study was to test their effectiveness to distinguish vegetation types and to define meaningful gradients related to humus quality (forms). The focus on the role of humus is justified by the fact that it is a direct result from the interaction between the type of soils and the components of ecological communities of which the plants are playing the primary role. We considered a dataset of 789 forest vegetation relevés (489 obtained from a data base and 300 made by us) and 847 species that we described by all the EIV and by the two Rogister indicators (RO). We grouped the relevés in 9 vegetation types according to the dominance of the most important and common tree species of Italy (1. Quercus suber, 2. Q. ilex, 3. Q. pubescens, 4. Q. cerris and Q. cerris-Q. Frainetto, 5. Carpinus betulus, 6. Fagus sylvatica, 7. Picea abies, 8. Abies alba, 9. Hygrophilous woodlands with Salix spp., Populusspp., Fraxinus oxycarpa and Alnus glutinosa) and we have used the evenness of the eigenvalues of the similarity matrices (Eλ), obtained by EIV and RO to test the separation between the 9 types. Eλ proved that the two Rogister’s indexes resulted more predictive than EIV. The analysis of the collected humus forms in the field confirms that the Rogister’s indicators are effective to identify the functionality of the humus forms and proves their correspondence with vegetation types: the Amphi humus is dominating in evergreen Mediterranean forests, Moder in mixed deciduous forests, Mull in Fagus sylvatica/Carpinus betulus and in hygrophilous forests, Mor in boreal forests