Tropical forests cover just 7% of the Earth’s surface, but store 25% of the global terrestrial carbon pool and account for a third of net primary productivity. Since they are so rich in carbon, net loss or uptake of carbon by tropical forests has important implications for atmospheric CO2 levels. Thus, tropical forests can speed up climate change by net emission of CO2 or slow it down by net sequestration.
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. Understanding the impacts of these changes so far is crucial to predict future responses.
Recent studies have shown that tropical forests have acted as carbon sinks over the last decades. However, it is unclear whether these forests have accumulated biomass also over the longer periods of time during which CO2 levels have risen and climate has changed. It is also unknown to what extent CO2 rise, climatic changes or altered forest dynamics have been responsible for the observed biomass increase.
The TROFOCLIM project has the objective to detect, explain and predict long-term climate change effects on tropical tree dynamics. To this end, three techniques which are new to this field are applied: tree ring analysis, stable isotope measurements and tree growth modelling.
This pan-tropical study will be conducted at three sites (Bolivia, Cameroon and Thailand), on 15 tree species and involves a total of 1500 sampled trees. We will test for gradual changes in long-term tree growth using tree ring data. Stable isotopes (13C, 18O) will be measured to reconstruct past climatic variation and detect physiological responses to CO2 rise. The influence of changes in forest dynamics on tree growth will also be assessed. Finally, physiological tree growth models and population models will be developed to unravel the complex interactive effects of climatic changes, CO2 rise and light climate on tree growth and population dynamics.
- Linking forests changes to CO2 rise and climatic changes (PhD Peter van der Sleen, completed)
- Detecting long-term effects of climate change on tropical forest growth: a pan-tropical approach using tree rings (PhD Peter Groenendijk, completed)
- Accelerated tropical forest dynamics, a pan-tropical tree ring study (PhD Mart Vlam, completed)