Phytogeographic Elements and Vegetation along the River Panjkora - Classification and Ordination Studies from the Hindu Kush Mountains Range

Abstract

Distributions of plant species over the earth’s surface are neither random nor even, but are geographic specific and characterized by specific sets of environmental and climatic factors. The current study aimed to classify the vegetation along the River Panjkora of the district Dir Lower, Khyber-Pakhtunkhwa, Pakistan into different phytogeographic units via exercising the Multivariate statistical techniques. Vegetation sampling was carried out through quadrat quantitative ecological techniques. Quadrats of various sizes i.e. 1 × 1 m2, 5 × 5 m2 and 10 × 10 m2 were taken for herbs, shrubs and trees, respectively. Inclusively 215 plant species belong to 22 different phytogeographic elements were analysed and documented. The most dominant category of phytogeographic element was Irano-Turanian with 77 species, followed by Cosmopolitan 25 species, Holarctic 23 species, Pluriregional 19 species, Mediterranean 16 species, Western Himalayan 14 species, Paleotropical 12 species and Eastern Asiatic 6 species. Eurasian, Euro-Siberian and Saharo-Arabian were represented by 3 species, Tropical, Sub-cosmopolitan and Pantropical contribute by 2 species while Paleo-temperate, South American, Australian, American, African and central Asian element by a single species. The relationship of various phytogeographic elements with different environmental variables such as pH, EC, TDS, Mn, Ni, Co, Cr, Cu, Cd, Zn, Fe, Na, Ca, Mg and K were determined via Canonical and Detrended Correspondence Analyses. We have observed that with the increase in nutrients concentration i.e., Mn, Co, Mg & Ni the number of Irano-Turanian, Cosmopolitan, Holarctic, Mediterranean & Western Himalayan elements increases while with the decrease in nutrients Cr, Cu, Cd and Na concentration the number of Australian, Sub-Cosmopolitan, Sahro-Arabian, Euro-Siberian, Tropical, American, and Pantropical phytogeographical elements decreases. Therefore, we conclude that there is a direct relationship between phytogeographic elements and soil nutrients that is obviously coupled with the genetic mechanism and natural selection of the species. The area hosting a diverse flora and having a strong correlation with a specifi sets of edaphic and climatic factors. We also elucidate that the area along the river is a hub for various phytogeographical elements and could further be explored from mycorrhizal, genetic, and species migration point of views.