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B440: Linking temperature changes and treeline dynamics on the Tibetan Plateau (Lead Supervisor: Ulf Büntgen, Geography)

Supervisors: Ulf Büntgen (Geography) and Paul Krusic (Geography

Importance of the area of research:

The impact of global climate change on the distribution of plant communities world-wide is of great interest to agrarian communities, vegetation modellers, resource managers, and economic planners. Quantifying the effects of rising temperatures and shifts in the hydrological cycle on the growth and composition of plant communities living at the upper limit of their natural distribution range is one way of estimating the degree and speed by which community structures are adapting. Representing the world's highest living organisms, the Tibetan Plateau is an extremely climate sensitive, and humanly significant region. Its glacier meltwaters are feeding all major rivers of South-East Asia. How changing vegetation cover affects local- to large-scale hydrological regimes and water available at different spatiotemporal scales will be of great importance for mitigating future climate change. The project will therefore study changes in seedling establishment at the highest forest borders.

Project summary:

Studying the age and species distribution of upper tree-line regeneration in climatically sensitive environments provides valuable information for how these environments will change in the near future. Under extreme conditions, where climate plays the largest role in regulating growth, reproductive success can be an informative measure of both the rate of climate change, and the immediate adaptation of plant communities. As dendrochronological techniques and technology have evolved, the study of age and growth rates of small seedlings is now feasible. This project will capitalize on that development and apply it to one of the world's most climate sensitive regions.

What the student will do:

In collaboration with Cambridge University's partners at Lanzhou University, the candidate will make repeated visits to the Qilian and Anyemaqen Mountains on the eastern Tibetan Plateau, to collect seedling samples from multiple upper treeline sites, with varying exposures, and measure their above- and belowground biomass, as well as age. This will involve preparing microsections from each sample and measuring growth-rates using high-powered microscopy. On the first visit, data-loggers will be installed to record hourly temperatures for the duration of the project. Logger data will be compared to the nearest met station to evaluate their relationship, both for interpreting results (temperature's influence on growth) and the degree to which distant station data represents treeline conditions. If successful modelling of climate's control on regeneration is achieved, this knowledge may be used to extrapolate over a broader region how upper treeline communities will change under climate prediction scenarios.

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Büntgen U, Hellmann L, Tegel W, Normand S, Myer-Smith I, Kirdyanov A, Nievergelt D, Schweingruber FH (2015) Temperature-induced recruitment pulses of Arctic dwarf shrub communities. Journal of Ecology 103: 489-501

Gou XH, Zhang F, Deng Y, Ettl GJ, Yang MX, et al. (2012) Patterns and dynamics of tree-line response to climate change in the eastern Qilian Mountains, northwestern China. Dendrochronologia 30: 121-126

1.Liang E, Wang Y, Piao S, et al. (2016) Species interactions slow warming-induced upward shifts of treelines on the Tibetan Plateau. Proceedings of the National Academy of Sciences 113(16): 4380-4385. DOI: 10.1073/pnas.1520582113

Follow this link to find out about applying for this project.

Other projects available from the Lead Supervisor can be viewed here.

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