Towards a model for projecting Net Ecosystem Production of the world forests

The global forest carbon budget constructed by Dixon et al. [Dixon, R.K., Brown, S., Houghton, R.A., Solomon, A.M., Trexler, M.C., Wisniewski, J., 1994. Carbon pools and flux of global forest ecosystems. Science, 263, 185-190] from national carbon budgets suggests that forests in mid- and high-latitude regions simultaneously entered into the phase of recovery and formed a significant sink for atmospheric carbon in the 1980s. However, constructing a carbon budget from forestry statistics gives rise to the question: what is the true value of the factor which converts the wood volume into the carbon stock? One may avoid this question by merging global carbon cycle modelling and forest inventory. This approach is illustrated by the case study of Japanese forests and it concludes that the key to projecting Net Ecosystem Production (NEP) of world forests lies with their age structure.