Dr Achyut Tiwari1, Mrs Samjhana Dhakal1, Dr Fan Ze Xin2, Dr Zhou Zhe-Kun2
1Tribhuvan University, Kathmandu Nepal, Nepal, 2Chinese Academy of Sciences, Mengla County, China
The response of altitudinal treelines is considered reliable indicators of the effects of rapidly changing climate. Demographic response including stand age structure and regeneration potential of tree species in treeline indicate treeline dynamics, and tree ring records of these forests show the growth limiting climatic processes. To find out how do treeline trees respond to changing climate, we studied different tree species (Abies spectabilis, Betula utilis, Abies georgei, Larix potaninii) in Trans-Himalayan zone, Nepal and Hengduan mountain, China. Trans-Himalaya included Chimang and Lete treeline sites whereas Hengduan region included Tianbao Mountain and Xiangcheng treelines sites. We reconstructed the age structure of tree by counting the yearly formed rings in cross-section of stem, and also by terminal buds count for seedlings and saplings. Limiting climatic factors for tree growth were identified by most closely linked periods of low and high growth in alpine treeline ecotone and proximity of timberline forest. We found that treeline to be moisture sensitive in trans-Himalayan zone Nepal, and temperature sensitive in Hengduan zone, China. We have found site specific rate of upward shifting of treeline in different regions. From our study we concluded that treeline dynamics is driven mainly by temperature and moisture climate, and is also highly sensitive to modifying factors such as microhabitat conditions despite of climatic suitability. Closer examination of belowground environment (soil temperature, moisture), separately to juveniles and adults, as well as of detail study of biotic interactions are equally important for making accurate prediction on treeline dynamics to changing climate.
Currently works at Tribhuvan University Kathmandu Nepal as an Assistant Professor . Achyut does research in Ecology, Forest dynamics, Dendroecology & Climate Variability.