Drought and warming are predicted to be key threats to tropical forests under future climate scenarios. Currently however, vegetation models struggle to predict how tropical forests will respond to environmental changes, largely because of a lack of mechanistic understanding concerning how and why trees respond to environmental stress. My research is therefore focused on determining how tropical forests respond to changes in climate. Currently I am involved in project led by Patrick Meir, Stephen Sitch and Maurizio Mencuccini within which we are investigating how drought affects the mortality risk of tropical trees.
The focal site of my research is the longest running tropical drought experiment site in the world, located in Caxiuana National Reserve, Para State, Brazil. At this site, plastic have been used to exclude 50% of the incoming rainfall from a 1ha old growth tropical forest plot since 2002. At this unique site we have been conducting a range of physiological measurements which are aimed at determining if certain combinations of hydrological and metabolic traits put some tree species at greater risk of mortality from drought than others. We will use results from this drought experiment, alongside data from other tropical forests across the globe, to guide development to the JULES vegetation model, with the aim of improving the ability of vegetation models to simulate drought responses in tropical forests.
My research has always worked at the interface between data collection and modelling. Previously I completed a PhD titled 'Reducing uncertainty in predictions of the response of Amazonian forest to climate change' at the University of Edinburgh in 2013. My PhD focused on collecting data on the responses of tree growth and coarse dead wood respiration to seasonal changes in climate, at sites across the Amazon. Collected data was collated with other data sites from a highly seasonal site in French Guiana and used as part of a data assimilation study targeted at assessing what aspects of model structure and parameterisation require development to enable accurate simulation of the seasonal change in carbon fluxes in tropical forests. Other research from my PhD included an assessment of the temperature and drought responses of 5 vegetation models, which were evaluated through comparison to data collected at a site in eastern Amazonia.
Alexander Crum Brown Road
University of Edinburgh