Abstract
A study was conducted to explore the plant biodiversity and vegetation structure of Biha Valley, District Swat, Pakistan. On the basis of the physiognomy of the vegetation the study area was divided into 19 stands. Line transect (50 m) method was used to sample the phytosociological attributes of the study area. PCORD software (version 5) was used to recognize communities by two-way indicator species analysis (TWINSPAN) and CANOCO software (version 5) for ordination analysis was done for detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) to find variation directories of different plant species. Different life-form classes and leaf size spectra were recorded according to the Raunkiaer classification. The floristic composition of the area consists of 203 plant species belonging to 154 genera and 70 families. The biological spectrum of the area indicated that Therophytes was dominant with 46.60% among the life-classes, followed by Hemicryptophytes having 15.53%. Leaf spectra of study area revealed that Microphylls was dominant (41.26%) followed by Nanophylls (32.04%). Seven plant communities were recognized by TWINSPAN classification, which showed that species diversity decreased with altitude. Moreover, the result indicates the importance of soil organic matter in top soil layers for plant species distribution. The increases in soil nutrients (OM, P, N, and K), improvement in site conditions (community cover, depth of litter, depth of humus, soil water content) and decrease in soil bulk density indicated the natural habitat restoration following abandonment.