Detecting long-term effects of climate change on tropical forest growth: a pan-tropical approach using tree rings

Although tropical forests cover just 7% of the Earth’s surface they account for a third of the terrestrial net primary productivity and store 25% of the global terrestrial carbon pool and. The gradual rise in atmospheric CO2 level since the onset of the Industrial Revolution and the resulting climatic changes have certainly affected tropical forest dynamics.

Project description

Being such an important factor in the carbon cycle, a net loss or uptake of carbon by tropical forests will have important implications for atmospheric CO2 levels. Tropical forests can be either a sink or a source of CO2 and can thus speed up or slow down climate change. Understanding how these changes have impacted forests so far is crucial to predict future responses.

Recently, studies have found that, over the last decades, tropical forests have acted as carbon sinks. These studies are however based on short term datasets and it is still unclear whether these accumulation of biomass occurred over longer periods of time or if they are caused by decadal scale climatic variation. Thus it is still unclear if the observed biomass increase was caused by CO2 rise, climatic changes or altered forest dynamics.

In my part or the TROFOCLIM project, I will look at whether growth of tropical trees has changed since the Industrial Revolution (~150 years), if this change has taken place globally (in South America, Africa and Asia) and if different species have reacted differently to the climatic changes. To this end I will apply tree ring analysis on 15 species from three sites (Bolivia, Cameroon and Thailand) in a total of ca. 1500 sampled trees. I will for gradual changes in long-term tree growth using this tree ring data by, for instance, comparing growth of juvenile trees now with that of adult trees when they were juvenile. I will also use the growth data to analyse wood productivity and assess sustainability of current (i.e. FSC) logging regimes for the species studied.

MSc theses

  • Berendsen, W. (2012). Projecting timber yields of Brachystegia cynometroides in Cameroon (Utrecht Univ.)
  • Kelly, F. (2012). The climate growth relationships and evidence for a juvenile selection effect in Brachystegia cynometroides a tropical tree species in Cameroon (Utrecht Univ.)
  • Mbia Nanga, W. (2012) Assessing climate change effects on growth rates of Brachystegia cynometroides (ekop naga) in a Cameroonian rainforest (Dschang Univ.)
  • Using the pioneer species Terminalia ivorensis as a disturbance indicator in a tropical forest in Cameroon. (Evelien Louwers, Utrecht Univ.)
  • Growth trajectories to the canopy: multiple choice? (Thomas Voswinkel, Utrecht Univ.)