Abstract/Summary

Deadwood is an important part of forest ecosystems, holding ~5% of global forest carbon, and providing other ecosystem services such as habitat for biodiversity, natural flood management, and production of woodfuel. Threshold volumes of deadwood, usually >20 m3 ha-1 , are aimed for, to help preserve biodiversity. The carbon stocks held in deadwood are now included as a pool to report in carbon inventories such as the Global Forest Resource Assessment. However, the exact contribution of deadwood from woodlands in Great Britain is unknown, with estimates of carbon stocks being based on simplistic calculations, assuming all deadwood is uniform and that volumes do not change over time. Additionally, there is little research into how volumes and carbon stocks vary between factors such as woodland type, origin, and management. In this work, we aimed to quantify the effects of these factors and ascertain how this compares to other forest floor materials. We also aimed to identify whether significant fluxes of dissolved organic carbon (DOC) were released from deadwood during decomposition, and whether this ‘primed’ soil microbes. This was carried out from plot scale experiments to national scale using data from the National Forest Inventory. We conclude that across GB, an average deadwood volume of 26 m3 ha-1 occurred. However, this significantly differed between countries in GB, woodland type, and management practices. Carbon stocks were calculated with wood density and carbon concentrations specific to tree species and decay class, which proved to significantly differ when compared to the standard calculation used for national reporting. Changes to wood density significantly affected the overall carbon stocks reported, while carbon concentration did not. It is possible deadwood provides a significant source of DOC into underlying soil, producing as much DOC per g material as leaf litter, though overall fluxes depend on the volume of deadwood present. The fate of DOC released by deadwood is currently unknown as there is no evidence that it causes a priming effect on soil microbes, and further study is required to ascertain whether deadwood derived DOC is strongly minerally-associated, or recalcitrant.