Potential von ober- und unterirdischen Totholz als Kohlenstoffsenke in Natur- und Wirtschaftswäldern / Potential of aboveground and belowground woody debris as a carbon sink in natural and managed forests
2 Bayerische Landesanstalt für Wald und Forstwirtschaft
P 1.6 in Ecosystem Function
Aboveground and belowground coarse woody debris have an unknown function in the carbon cycle of forests. This project aims to quantify the carbon pools and calculate the turnover time of organic carbon in mature forests with high amounts of deadwood in comparison with neighboring managed forests. The organic carbon at different soil depths, aboveground and belowground coarse woody debris are considered. Three Bavarian forests with different tree composition were chosen. Dead wood and woody debris (cross section >7 cm) are appraised and classified depending on their state of decomposition. To calculate their turnover rates, the year of tree death is determined with the help of dendrochronological cross dating and the radiocarbon method. In the managed forests the decomposition of snags and coarse roots is assessed along a time sequence (year of forest thinning) to estimate the carbon pool of belowground dead wood. The influence of coarse woody debris on soil organic carbon is evaluated by taking 30 litter samples as well as soil cores of 1 m depth in each of the six forests. The organic carbon content in different soil depths is measured and, using radio carbon signature, the turnover rate of carbon in different soil fractions is modeled. The influence of coarse woody debris on the stability and turnover time of carbon is calculated by the comparison of mature and managed forests. Finally, the carbon pool of coarse woody debris and soil carbon is compared to that of living trees to evaluate its function as a sink for atmospheric carbon dioxide in mature and managed forests. A better understanding of the carbon cycle of forests and how it is influenced by different management practices is expected. It can be clarified whether mature forests, due to coarse woody debris, are temporal or durable carbon sinks.