To assign plots (10 m
the cluster analysis algorithm of the SYN-TAX programme (Podani, 2001); details are described in Supplementary material I. Using the resulting dendrogram, we established three vegetation groups based on the similarity analysis in the Juice programme (Tichý, 2002). In addition, Juice programme also calculated the Potential Annual Direct Incident Radiation Index (Equation (3); McCune and Keon, 2002; PADIR) for each plot.The calculation employs slope, aspect and latitude as the entry parameters only. Aspect has to be ‘folded’ prior to calculation, to make this variable linear and symmetrical about the northesouth axis. In this respect, PADIR strongly influences the habitat temperature and may serve as a proxy for evaluating site dryness or water availability in terrestrial vegetation under the normal water supply (i.e., in mesic conditions, which holds true for our plots). Since the calculation does not give account to cloud cover, regional differences in the atmospheric transmissivity or shading by adjacent topography/vegetation, it is rather approximative but still an efficient method how to capture the solar energy input into habitats.