STUDIES REGARDING THE INFLUENCE OF THE GEOLOGICAL SUBSTRATUM ON VEGETATION USING MODERN METHODS

Abstract

The main objective of the study is the analysis of the effects of the geological substrate and of the geomorphological diversity on the characteristics of the vegetation (the diversity of species, the diameter of the trees). The study area is made up of the Cioclovina karst area and the crystalline area near it, which are located in the Dacian Plateau in the ?ureanu Mountains. Within the study, a series of geomorphological variables were calculated to establish geomorphological heterogeneity, namely: slope, slope exposition, soil drainage, land humidity index, and water erosion power. These variables were calculated using the SAGA GIS program. After the variables were derived, they were divided into classes, transformed from raster into polygon and aggregated into a single layer using the union function, to get all variables in the attribute table. Subsequently, the layer resulting from the unification of the variables was, in turn, united by using the union function with a Grid with a 2-ha resolution made with the function Created fishnet. Finally, each cell of the grid was classified into high geomorphological heterogeneity or low geomorphological heterogeneity. These operations were performed in the ArcGIS Desktop program version 10.7.1. In the two analysis areas located in the ?ureanu Mountains, for areas with high/low morphological heterogeneity values correspond to values of diversity indices of high/low forest species. Within the analysis performed, the results between the correlation between geomorphological heterogeneity and diversity indices were different between the karst area and the crystalline area. In the karst area, the correlation between geomorphological heterogeneity and the Shannon index is positive. Also, in the karst area, the correlation between geomorphological heterogeneity and the dominance of species and that between species heterogeneity and the average diameter is negative. In the crystalline area, the correlation between geomorphological heterogeneity and the richness of species as well as that between heterogeneity and the Shannon diversity index is negative. The correlation between geomorphological heterogeneity and the dominance of species as well as between heterogeneity and the average diameter is positive, because the land humidity index is high.