A Grazing Capacity Model with Fuzzy Inference System in Semi-steppe Rangelands

The research objective was to investigate effects of climate variability on monthly growth of Aglaia odoratissima and Hydnocarpus ilicifolia which are the dominant tree species in lower canopies of dry evergreen forest and generally found at the Sakaerat Environmental Research Station (SERS), northeastern Thailand. For one year of the investigation, monthly data of tree leaf phenology, inside bark diameter (IBD) and outside bark diameter (OBD) increments were examined. These data were related to soil moisture content and climatic data of monthly rainfall, temperature and relative humidity. The results showed that leaf phenology of A. odoratissima and H. ilicifolia illustrated leaf maturation throughout the year, while young leaves were abundant in the rainy season and leaf abscission was rarely found throughout the year. The IBD increments of these species on transverse surfaces could be detected throughout the year and the most rapid increments were detected in the rainy season, while OBD increments of both species shrank in the dry season and swelled in the rainy season. Using path analysis (PA), climate variability was found to be significantly related to leaf phenology of A. odoratissima and IBD increments of H. ilicifolia; and it was also significantly related to OBD increments of both species