Composition of plant communities driven by environmental gradients in alpine pastures and cold desert of northwestern Himalaya, Pakistan

摘要

Alpine life zones exist at the cold edge above the tree line in mountains where tree species do not grow, however, a large plant diversity thrives due to alpine climate adaptations to short growing seasons and low temperatures. Keeping this phenomenon in view, study was designed to determine the influential environmental variables responsible for structuring the plant communities in the alpine pastures and cold desert of Northwestern Himalayas, Pakistan. The vegetation of the aforementioned study area was quantified by following the Line transect (50 meters) method along the geographic, slope, edaphic and climatic gradients. All the recorded data of plant species and environmental variables were analyzed by various statistical softwares’ ( i.e., PCORD, CANOCO and R 3.6.1). Thirty-nine species recorded in 13 stands were grouped into two major plant communities (i.e., Poa-Bistorta-Primula and Bistorta-Poa-Primula) . Poa-Bistorta-Primula community has the highest number of plant species (39 species) as well as the highest value of alpha and beta diversity (2.785 and 0.916, respectively) and Pielou’s evenness (0.865) in Bistorta-Poa-Primula community. Due to the high elevation, severe low temperature is the feature throughout the growing season. Such severe climatic environment is worsened by xeric conditions which led to very short growing season from July to September. The recognized indicators of such harsh environment might be useful in monitoring variations in plant communities resulted in response to environmental changes.