Tree mortality and drought: leveraging the power of big data

Why do trees die? How do the rates and drivers of tree mortality vary from the tropical rainforest to the boreal? How do these mortality rates affect forest structure? These questions are crucial in order to understand large-scale forest dynamics. They are also of fundamental importance for our understanding of how climate change will evolve because forest ecosystems are huge stores and sinks of carbon.

Hot droughts are expected to become more prevalent under climate change (Seneviratne et al., 2012), resulting in a lot of focus in recent years on how trees die under drought (Allen et al., 2015; Hember et al., 2016; Rowland et al., 2015). Yet little is known about the extent to which drought usually plays a role in tree mortality in the different ecosystems around the world. For instance, is drought a more prevalent driver of tree mortality in areas that are commonly hot and dry, or in those where such conditions are a relatively rare occurrence? Which types of tree are most vulnerable and how is this affected by their status in the ecosystem?

This project will apply the latest machine learning techniques developed for genomics problems (Basu et al., 2018) to identify patterns and relationships between drought and tree mortality in of a range of forest inventory and remote sensing datasets, spanning global forest biomes. This new process-knowledge will then be integrated within a state-of-the-art global ecosystem model (Smith et al., 2014), to understand the implications of drought-induced tree mortality for current and future forest structure and carbon cycling, thus achieving a complete flow from observations, to understanding, to implications.
This project has the potential to substantially advance understanding of how drought interacts with forest at a biogeographical level – the scale that is most relevant for understanding feedbacks of tree mortality on future climate change.
The studentship collaborates with Operation Wallacea, a major source of inventory data from the tropical forests, which will be analysed for the first time for tree mortality within this project. The student will be part of a larger team working on tree mortality through the TreeMort project (more.bham.ac.uk/treemort).
The studentship is offered in collaboration with Operation Wallacea who have a unique forest inventory dataset for several tropical locations which has never been analysed for tree mortality. This offers an excellent opportunity to analyse a new dataset in close collaboration with those who have collected it, before expanding the methods to take in a wider range of datasets and forest types.
The student will benefit from the large network of international collaborators taking part in the TreeMort project, based at Birmingham. They will thus be part of a much larger team working on the broad topic of tree mortality.
Further details:
https://more.bham.ac.uk/treemort
http://bioatmo.wordpress.com