Measuring Tree Death and Damage in Tropical Forests

Although tree mortality is key to predicting forest response to global changes, much uncertainty remains regarding its causes and consequences in tropical trees. This study proposes a rapid, repeatable, and inexpensive assessment of individual tree death and damage. A new field protocol minimizes the effort required at each tree, enabling frequent assessments of more trees. A comprehensive assessment of tree damage coupled with the identification of factors associated with tree death will lead to an improved understanding of the causes of tree mortality and estimates of biomass fluxes in tropical forests.

Tree mortality drives changes in forest structure and dynamics, community composition, and carbon and nutrient cycles. Since tropical forests store a large fraction of terrestrial biomass and tree diversity, improved understanding of changing tree mortality and biomass loss rates is critical. Tropical tree mortality rates have been challenging to estimate due to low background rates of tree death and high spatial and temporal heterogeneity. Furthermore, the causes of mortality remain unclear because many factors may be involved in individual tree death, and the rapid decomposition of wood in the tropics obscures evidence of possible causes of tree mortality. To assess tree mortality in tropical forests, researchers developed a field protocol that focuses on the rapid, repeatable, and inexpensive assessment of individual tree death and damage. They successfully tested the protocol, conducting annual assessments of >62,000 stems in several ForestGEO plots in Asia and the Neotropics. Standardized methods for assessing tree death and biomass loss will advance understanding of the underlying causes and consequences of tree mortality.