TreeMORT: Redefining the carbon sink capacity of global forests: The driving role of tree mortality

TreeMort is about improving our understanding of tree mortality across the globe. It attempts to answer questions such as: How do the rates and drivers of tree mortality vary from the tropical rainforest to the boreal? What is the relative importance of the different processes responsible for tree death? How are these likely to change going into the future? Are there strong feedbacks with the carbon cycle and climate?

The answers are largely unknown, yet are fundamental to understanding how forests function, and will help assess forest resilience under climate change. It is also crucial to understanding the role of the terrestrial biosphere in absorbing anthropogenic emissions of carbon dioxide. The terrestrial biosphere currently removes ca. 30% of annual anthropogenic CO2 emissions from the atmosphere, greatly moderating the rate of climate change.

The majority of this terrestrial carbon sink is believed to result from increases in woody biomass. However, whether or not the size of this sink in vegetation will persist, strongly intensify, or decrease in the coming decades remains very uncertain. A very large part of that uncertainty stems from not knowing how long carbon will remain in vegetation. Better understanding of the behaviour of this sink is thus crucial if we are to be able to develop accurate carbon emission budgets consistent with limiting climate change to the 2°C global mean temperature target enshrined in the recent Paris Climate Change Agreement.

The TreeMort team will draw on a range of data sources including forest inventories, satellite observations and plant trait data to put together a global picture of tree mortality rates and drivers. They will use this information to inform updated mortality functions for terrestrial vegetation models, and thus aim to substantially advance understanding of large-scale forest form and function. The project started on 1st February 2018 and will run for five years.

Project website