HOW ENVIRONMENTAL VARIABLES CAN DETERMINE THE CHIR PINE (PINUS ROXBURGHII SARG.) DISTRIBUTION IN SWAT HINDUKUSH RANGE OF PAKISTAN: CURRENT AND FUTURE PROSPECTIVE OF THE SPECIES.

Distribution patterns of plant species and their relationships with physiographic, soil and climatic variables were investigated in the subtropical pine forests across the natural limits in the Swat, Hindukush range of Pakistan. A vegetation survey identified 9 tree species belonging to 8 families and 8 genera, which were classified into 3 distinct vegetation communities with an average density ranging from 512-1231 individuals ha^-1 and basal areas of 31.6-36 m² ha^-1. Total density and basal area values for tree species located at higher elevations were lower than those in the middle and low elevation communities for all the species. We found that P. roxburghii had unimodal size distributions, suggesting that these populations are not at equilibrium and are changing over time. CCA-Ordination with the associated Monte Carlo permutation test was employed to explore the patterns of variation in vegetation distribution and identified elevation and soil organic matter as the most influential variables responsible for the changes in species composition. The MaxEnt predictive modeling results clearly indicate a significant difference in the present predicated inter-site floristic composition and distribution of the species, suggesting an overall restriction to the south, whereas, the future distribution model suggest a shift towards the neighbouring districts in the west. This study identified few significantly important environmental variables linked with P. roxburghii associations and their distribution across the study area. We recommend additional research that includes multiple sampling from varied locations and other abiotic and biotic variables throughout Pakistan and neighbouring countries for better understanding of the species niche modeling. [ABSTRACT FROM AUTHOR]