Effect of forest fire on floristic composition, structure, dominance and species richness in subtropical pine forest of Ponda watershed, Rajouri, J&K

Abstract

Forest fires have profound impacts on physical environment including land cover, land use, forest ecosystem and biodiversity. In the present study the effect of fires on floristic composition, structure, dominance and species richness in subtropical pine forest of Ponda watershed, Rajouri, J&K, lying at an altitude range of 800 m to 1000 m above mean sea level, was assessed. The forests in the study area were divided into two strata i.e., burnt and un-burnt forest. Random sampling was carried out by laying out forty sample plots in all, with twenty sample plots in each strata covering burnt and unburnt forest sites of the study area. The plot dimensions of 20m x 20m were used for studying trees and 5m x 5m for shrubs (laid within the plots for trees). The density, basal area and IVI along with diversity and concentration of dominance of trees and shrubs in both forest sites were studied. Similarity index was also calculated for burnt and unburnt forest of the study area. The results show that the total density and total basal area of trees and shrubs was highest in un-burnt forest sites with density values of 468.75 and 5284 individuals/ha and 85.33 m2/ha and 25.42 m2/ha, respectively. The results on the basis of the comparison of IVI values of all species in both forest stands also reveal that the respective dominant tree and shrub species were Pinus roxburghii and Carissa opaca. The calculated values of Shannon-Wiener, Margalef and Menhinick indices i.e. 1.93, 2.53 and 0.82 for trees and 1.80, 2.08 and 0.44 for shrubs, respectively, reveal that the species richness and diversity was high for unburnt forest stand whereas, Simpson’s index value of tree (0.48) and shrub (0.75) show that an concentration of dominance was highest in burnt forest stands. The calculated value of Sorenson’s and Jaccard’s index of similarity for trees (0.60 and 0.43) was maximum as compare to shrubs (0.47 and 0.31) which shows that forest fire have profound effect on shrub than trees.