Temperature rise from anthropogenic climate change is often especially pronounced at high elevations, where it threatens the survival of many species. This project will study how the upper elevational boundary of trees at about 4000 m is responding to climate change in relatively pristine forests of the Nepal Himalayas. Preliminary work suggests that the upper elevational boundary of one of the dominant trees, a species of Rhododendron, is rapidly shifting upward, with individuals at the highest elevations being more tolerant to extreme climate conditions but less tolerant of competition than individuals only 150 m lower. This project will expand this work to include additional measures of differences between individuals and sites that differ in key characteristics such as aspect and rainfall. Results will help show how montane species respond to climate change, how responses may depend upon interactions between species or site specifics, and which mechanisms drive shifts in range at high elevation and determine associated risks of local extinction.
The project will train students in field methods and provide them with an opportunity to explore natural areas distant from cities. Additionally, the project will form a new international collaboration between researchers at the University of Texas and Tribhuvan University and the Nepal Academy of Science and Technology in Nepal. The co-PI will teach short courses to undergraduate and graduate students in Kathmandu on current trends in ecology, climate change research, and advanced statistical tools. Outreach presentations to the general public will be given in Jumla and Kathmandu to increase their awareness of climate change and its impacts on their lives.
Temperature rise from anthropogenic climate change has been, and is projected to continue to be, strongest at highest elevations. We studied tree line dynamics in pristine forests of the Nepal Himalayas where human influences have been minimal for centuries. Having the highest rate of current warming while supporting unique and rich plant and animal communities, the Himalayas are particularly vulnerable to future climate change. A better understanding of climate change impacts (direction, magnitude and rate) on natural systems of the Himalayas is critically important for preserving it as a biodiversity hotspot. Our analysis reveals that the upper elevational boundary of an abundant tree species Rhododendron campanulatum is shifting upward. Young plants (<2m tall) of the species are more abundant and have lower mortality above treeline than below treeline. Mature plants (>2m tall), on the contrary, are more abundant below treeline than above, and did not show the reduced mortality that young individuals exhibited above treeline. These results, along with faster regeneration of the species above treeline than below, indicate that Rhododendron campanulatum population is shifting upward, along with creating a new treeline made up of this species above the old treeline, as a result of recent amelioration of temperature. The shift in population, however, is achieved by maintaining genetic differences in low temperature tolerance even across a small elevational gradient. Our field experiments indicate that plants at the extreme limit of the species range have achieved adaptation for tolerance of more extreme lower temperature but are less tolerant of competition compared to plants only 150m lower in elevation. These findings represent about half of the outcome of the funded project; for the rest, data is still being analyzed. During the course of the study, I (Kumar Mainali) taught ecological principles and climate change impact on biodiversity, data analysis, and experimental design. I ran three training workshops (2 days to 2 weeks long) in Kathmandu, Nepal and covered basic and advanced statistics, with data analysis, in the workshops. A total of 87 people attended my workshops, most of them PhD students, young scientists and faculties. My field crew consisted of current or recently graduated students from the universities in Kathmandu. I trained a total of 15 local nascent ecologists primarily in field methods but I also taught them ecology, experimental design and data analysis before and after the field visit. An undergraduate student at The University of Texas at Austin of Nepalese origin also joined my field crew. Additionally, this project formed new collaborations between researchers at UT-Austin (a tier-one research institute) and in Nepal. Collaborators included an assistant professor at Tribhuvan University, Kathmandu, three scientists from the Nepal Academy of Science and Technology (NAST), Kathmandu, and two officers at Department of Plant Resource, Jumla, Nepal. Many informal discussions on climate change impact were conducted with general public in Langtang and Jumla to increase their awareness of climate change and its impacts on their lives.
