NORTH-SOUTH FACING VEGETATION GRADIENTS IN THE VILLÁNY MOUNTAINS: A CASE STUDY ON THE POPULATION AND THE COMMUNITY LEVEL

Abstract

The study of gradients can provide basic information about the ecology of plant populations as well as about community organization. In this study, north-south facing vegetation gradients were investigated in a submediterranean region of South Hungary. Vegetation was examined along five contiguous belt transects, each 200 m long, crossing the mountain ridge or plateau. Plant community sequences were identified visually during field studies. Moreover, community boundaries were delineated objectively, using the moving-split window analysis. In addition, number and size of the population patches were analyzed. This study revealed that mesic forest communities of the northern slopes are replaced by shrubforests and closed rock swards near the ridge, whereas mosaics of shrubforests and open rock swards occur on the southern slopes. Number of significant community boundaries was higher on the southern slopes than on the northern ones. Southern slopes support much more plant species. They have more population patches, which are significantly smaller than patches of the northern slopes. Community sequences along north-south gradients in the Villány Mts are similar to those of the nearby mountainous areas, with one fundamental difference of the xeric grasslands near the ridge. The conclusion of the present paper is that this sequence represents a transitional type between the submediterranean-subcontinental and the continental types. In addition, southern slopes support higher biodiversity and are more patchy than northern ones.