Ecological gradient analyses of plant associations in the Thandiani forests of the Western Himalayas, Pakistan

Authors: WAQAS KHAN, SHUJAUL MULK KHAN, HABIB AHMAD, AAMIR SHAKEEL, SUE PAGE

Abstract: In the summers of 2012 and 2013, vegetation of Thandiani in the Western Himalayas of Pakistan was surveyed and quantified. We took evidence from relationships between 252 species and 11 measured environmental factors as well as changes in the associations' structure among 50 analysed stations with 1500 m² plots. We analysed how the plant associations differ and develop under the influence of their respective ecological gradients. Preliminary results showed that the family Pinaceae was the most abundant family with a family importance value (FIV) of 1892.4, followed by Rosaceae with FIV = 1478.2. Rosaceae, represented by 20 species, was the most dominant family, followed by Asteraceae and Ranunculaceae with 14 and 12 species each, respectively. Analyses via CANOCO software version 4.5 and GEO database demonstrated strong correlations among species distributions and environmental variables, i.e. elevation, topography, and edaphic factors. Our findings show an increase in species diversity and richness from lower elevation (1290 m at sea level (m asl) to higher elevation (2626 m asl). It is evident that aspect, elevation, and soil factors were the decisive variables affecting qualitative and quantitative attributes of vegetation in the study area. The P value ≤ 0.002 confirms a significant impact of abiotic factors that bring variation in vegetation. A 3D view of the study area was generated in ArcScene showing all the five plant associations. Graphs of scatter plot, point profile, and 3D line profile were added to the layout of plant association maps. The habitats of the five association types overlapped broadly but still retained their specific individuality. The execution of GIS framework gave spatial modelling, which ultimately helped in the recognition of indicator species of specific habitat or association type. These findings could further be utilised in devising the forest policy and conservation management. This study also opens new doors of research in the field of biogeography, systematics, and wildlife.

Keywords: Plant associations, Ecological gradient, deterended correspondence analysis, canonical corresponding analysis, electrical conductivity, organic matter, species richness, ecological gradient, geographic information system, Thandiani forests of Himalayas, Pakistan

Full Text: PDF