What controls sensitivity to drought-induced mortality in tropical forests?

OCTF seminar followed by drinks – all welcome

Increasing drought frequency and intensity are thought to be key climatic threats facing tropical forests this century. During severe drought, trees are at risk of mortality through a combination of processes including deterioration of hydraulic function and carbon limitation. Understanding what triggers the process of tree mortality is vital if we are to understand how tropical forests will respond to climate change. We present new results from a unique long-running rain fall exclusion experiment in Brazil. The study compares replicate species on a control and droughted plot that have either experienced a normal climate or a long term reduction in through-fall of 50%. We find differing mortality risks in two groups of trees, that have been found to be either drought resistant or sensitive. Using a series of detailed eco-physiological measurements we also demonstrate that the process of forest decline during drought is guided by hydraulic deterioration, rather than a limitation in carbon supply. This process of decline can be shown to have significant consequences for the cycling of both carbon and water within tropical forests exposed to prolonged drought stress.

From 2006-2009, Lucy Rowland studied geography at the University of Oxford, where she met Yadvinder Malhi and undertook a dissertation looking at tropical forest tree growth in Peru. This led to an internship at the Met Office looking at tropical forest responses to climate change in global models and then to a PhD at the University of Edinburgh. Lucy’s PhD focused on combining detailed field measurements with vegetation model development to advance understanding and prediction of tropical forest responses to change. Following her PhD, she undertook a post-doc with Professor Patrick Meir focusing on the drivers of drought-induced mortality at the world’s longest running tropical forest drought experiment. Currently she is doing a post-doc at the University of Exeter, with Professor Stephen Sitch, looking at how to model drought-induced mortality in dynamic global vegetation models and is soon to start a NERC 5 year fellowship.