Abstract

The objective of this study was to assess the effects of soil characteristics and physiographic factors (slope, aspect and elevation) on vegetation distribution. We ultimately ascertained the most important characteristics on the establishment, regeneration and distribution of species in Asalouyeh mountain forests south of Iran. Vegetation sampling was performed using a randomized-systematic method and plot area was determined by the "minimal area" method. Data relevant to the presence and abundance of plant species was also analyzed. Plant ecological groups were formed from vegetation data (TWINSPAN) and ordination analysis (DCA). Geographic information system (GIS) was employed for mapping plant ecological groups and for our digital elevation model (DEM). Ordination analysis was performed using DCA to determine the floristic composition of plant ecological groups and samples. To investigate the relationship between vegetation and soil characteristics, soil samples were selected from both organic horizons (0 to 7 cm) and mineral layers (7 to 25 cm). Soil characteristics such as texture, lime, and moisture, as well as pH, EC, N, P, C and KOH were included for analysis by the PCA method. The results showed that the vegetation distribution pattern was primarily related to soil characteristics and elevation. Additionally, the results revealed that the regeneration, establishment, growth, and sustainability of each plant species are dependent on the unique environmental conditions of soil characteristics and physiological factors.

Key words: Forest, soil, establishment, ordination, plant group.