Future carbon sequestration in Europe-Effects of land use change

Important land use changes are expected in the European Union (EU) the coming decades, having effects on carbon stocks in soil and vegetation. We assessed how future land use change (LUC) can influence future carbon stock change in soil and vegetation in the EU. The emphasis is on the role of LUC in the overall carbon balance of the EU biosphere. Because LUC is the most dynamic driving factor of terrestrial carbon stock change, it is important to account for the dynamics of LUC in carbon stock change modelling. The major challenge in coupling a carbon model and a LUC model is the difference in spatial and temporal resolution generally used in these modelling approaches. We used a high-resolution LUC model and a carbon bookkeeping approach that takes into account effects of soil and forest age on carbon stock changes. These approaches best fit the chosen resolution and extent in a consistent manner. Four SRES scenarios that cover a range of possible future developments were evaluated: Global Economy (A1): lean government, strong globalization; Continental Markets (A2): lean government, regional cultural and economic development; Global Co-operation (B1): much governmental intervention, strong globalization; Regional Communities (B2): much governmental intervention, regional cultural and economic development. If land use remains unchanged, carbon sequestration rates are expected to decrease by 4% in 2030 relative to 2000. LUC causes an additional sequestration rate decrease in the A2 scenario of 2% in 2030. In the other three scenarios, sequestration rate increases by 9-16% in 2030 relative to 2000. In 2030, the terrestrial biosphere in the EU is expected to sequester between 90 and 111 Tg C year-1. This is 6.5-8% of the projected anthropogenic emissions. In the B2 scenario, the highest sequestration rate increase is expected (15 Tg C year-1). Clear differences are found in the spatial distribution of sinks and sources between the scenarios, illustrating that land use is an important factor in future carbon sequestration changes that cannot be ignored