Understanding the global carbon cycle is the prime scientific research question of the day. The global biosphere is thought to take up about 2.3 gigatonnes of carbon each year. At the moment the European biosphere is believed to take up 9–12% of all European emissions. To mitigate climate change it is important to know into which carbon pools these emissions are going, the rate of uptake in future and how this can be managed. Moreover, in an increasingly changing environment, mitigation measures will have to incorporate strategies for adapting to climate change.
Vegetation and management perspective
Although forests are vulnerable to climate change they are also part of the solution. The Environmental Sciences Group is studying how these two processes interact through fundamental research to clarify our understanding of the European biospheric carbon cycle and applied research in support of the Dutch reporting of greenhouse gas balances to UNFCCC. The research spans a broad range of topics within the climate change arena, but is mainly concerned with the role of the European biosphere in the carbon cycle. This is examined from an atmospheric perspective and from a vegetation and management perspective.
In order to understand the current behaviour of European forests it is important to investigate the changes that have taken place in the past. We have assessed the historic carbon balance using international statistics on European forests and discovered that the carbon sink in European forests has gradually increased over time to 0.17 Gt C per year at present. European forests are clearly recovering from past degradation caused by overharvesting, grazing and litter raking. Most of these practices ceased at the beginning of the last century, but the forests are still in the process of recovery. Although natural disturbances have increased over time, they have not changed this trend towards recovery. We are also investigating the future carbon balance: how long will the carbon sink continue and how can we manage it? This is a key question with respect to the Kyoto Protocol, under which countries must choose whether they will employ ‘forest management’ to achieve their emission reduction targets. Our CO2FIX model can be used to examine this question. It has been downloaded more than 2000 times worldwide and is widely accepted as a tool for addressing issues related to the Kyoto Protocol.
The behaviour of forest ecosystems locally is currently studied using micrometeorological techniques, such as the eddy covariance method. This sensor can be used to make direct measurements of the CO2 flux over a forest canopy. One site in the Netherlands (Loobos) has been continually monitored for over 10 years now in one of the longest studies in Europe. For long-term and larger-scale analyses, combinations of forest resource model outcomes and biogeochemistry models are used in the CAMELS project. This approach makes use of the strengths of each of the modelling groups. Future research will not only examine the strength of the carbon sink, but also combine sink estimates with insights into the resilience of forest systems. If forests prove to be vulnerable to climate change, then eventually more carbon will be lost, accelerating the processes of climate change.
Future research will investigate forest carbon dynamics and climate change from many points of view, including relations to water issues, biodiversity and wood production.