CREAFTalk with Pieter Zuidema: Impacts of drought on tree growth across the tropics
Spain
An increasing incidence and intensity of droughts under anthropogenic climate change jeopardizes the potential of tropical forests to capture and store carbon in woody biomass and act as CO2 sink. A pantropical quantification of drought impacts on tree stem growth is needed to evaluate this risk.
We assessed drought impacts in a pantropical network of 477 tree-ring chronologies and found modest stem growth declines (median: 2-4%) during drought years. Growth declines were larger for dry-season than wet-season droughts, specifically for Gymnosperms, and at hotter and more arid sites. In addition, we produced a first pantropical estimate of drought-associated mortality. For the 10% driest years we estimate a 0.1%/y additional mortality.
Thus, drought impacts on tropical forest carbon sequestration through stem growth have been small and short-lived, but will aggravate under climate change, in particular through associated elevated mortality risks.
Pieter Zuidema (full professor at Wageningen University, the Netherlands) is a forest ecologist studying effects of atmospheric and climatic changes on tropical forests worldwide. He uses a variety of techniques to do so: physiological studies, tree-ring analyses, wood chemical analyses, demographic studies and dynamic vegetation modelling. Long-term carbon sequestration in tropical forests critically depends on wood formation. To study the ecological processes driving wood formation at the pantropical scale, he initiated and leads the tropical tree-ring network (tropicaltreeringnetwork.org). During the past 5 years, this network has collected and analyzed tree-ring data from 500 sites, >10,000 trees and 150 species, provided by >200 researchers. The network spans all tropical continents, and includes sites in dry to everwet, and lowland to montane tropical woody vegetation.
