Phytosociology and Dendrochronological Investigation of Shangla Pine Forests of Khyber Pakhtunkhwa Pakistan

Abstract

The focus of our study was quantitative vegetation description, community analysis, structure of forests, multivariate analysis and dendroecology, (age, growth rates) investigation of Shangla Pine Forests of Khyber Pakhtunkhwa. Forty different stands dominating conifers species were selected randomly for this study using point centered quarter method (PCQ). In each stand 20 points were taken at every 10 meter intervals. Ground flora was also recorded by using circular plot of 2.5 meter at each point. Phytosociological attributes (relative density, relative frequency and relative basal area) and absolute values (density ha -1 and basal area m 2 ha -1 ) were calculated for each site. On the basis of importance value index and floristic composition five communities and four pure monospecific conifer stands were recognized i.e. Abies pindrow - Picea smithiana community, Pinus wallichiana - Abies pindrow community, Cedrus deodara - Pinus wallichiana community, Picea smithiana - Pinus wallichiana community and monospecific stands of Pinus wallichiana, Abies pindrow, Pinus roxberghii and Cedrus deodara. Among these forty stands Pinus wallichiana was present in 32 stands which was the leading dominant species with the highest density of 296 individuals ha -1 followed by Abies pindrow which was observed in 9 stands with highest 86 basal area m 2 ha -1 , Picea smithiana and Cedrus deodara recorded from three locations, Pinus roxberghii from 2 sites and angiospermic tree Quercus baloot from 4 sites with very low 47 density ha-1 and 4.1 m 2 ha -1 basal area. Structure of these forests showed gaps in early dbh size classes as reported in many forests of Pakistan; however these gaps were due to illegal cutting and due to failure of regeneration. Therefore these forests are considered unstable. 19 Multivariate analysis i.e. classification, ordination of tree species and NMS for understory vegetation was applied to examine the vegetation pattern. Four major groups of tree vegetation were recognized for cluster analysis. All the groups were superimposed on ordination plane. Environmental characteristics (topographic factors, edaphic factors, soil physical properties and soil nutrients) were also evaluated for each group. Elevation was highly significant (P<0.001), pH, maximum water holding capacity, soil moisture and soil physical properties (sand, silt and clay) also showed significant (P < 0.05) relation, while the other variables did not show any significant relation. On the ordination basis elevation showed significant (P < 0.05 to P < 0.001) relation on axis 1 and axis 3. Cluster analysis of understory vegetation were also resulted into four groups, all these four groups were superimposed on ordination plane. Age and growth rates of different sized trees of four dominant tree species Pinus wallichiana, Abies pindrow, Cedrus deodara and Picea smithiana were estimated. In our study Age and growth rates of all four species showed highly significant correlation, diameter and age showed significant relation among three species, except Abies pindrow which did not show significant relation. The highest age was 326 years for Pinus wallichiana with 143 cm dbh sized tree. For Abies pindrow highest age was 412 years with 114 cm dbh size tree. Cedrus deodara 134 cm dbh tree attained 339 years while Picea smithiana highest age was 320 years. Forest ecology (Dendroecology) was also investigated to understand growth rates and its changes with the passage of time from seedling stage to mature tree of the study area. For this purpose three different aspects, variation in growth rates with time, variation in growth rate with different dbh size classes and variation in mean age with different diameter classes were find out. Growth rate was good in 18 century while it was decreased with passage of time. All these aspects showed non-ideal condition of the forest growth due to disturbances. Therefore forests are in critical situation and prompt action should be taken to save these forests.