Wood decomposition and its role in the forest carbon cycle

Abstract

Dead wood is the largest detrital component within forests, comprising a significant portion of the total carbon (C) pool. Despite its ecological importance, there is insufficient information on the factors affecting wood decomposition, and there are no mechanistic models that effectively simulate wood decay and the incorporation of wood C into soil across North America. Therefore, the objective of this experiment is to establish a long-term experimental framework to serve as a foundation to study decomposition processes in wood and the associated interactions with the underlaying soil. The basic approach is to assess the interactions of site conditions with biological processes mediating wood decomposition by incubating common wood substrates, loblolly pine (Pinus taeda L.), aspen (Populus tremuloides Michx.), and birch (Betula papyrifera Marshall) logs in forest ecosystems with different soil and environmental conditions. The unique aspect of this study is the use of logs from Free Air Carbon Dioxide Enrichment (FACE) sites in North Carolina and Wisconsin, which have a distinct δ13C signature that can be followed through the wood decomposition process, thereby providing the capacity to assess the translocation of wood C into soil organic matter pools. In 2011, FACE logs were placed horizontally on the soil surface and vertically without soil contact to simulate standing dead trees, the two dominate positions of dead wood in forest ecosystems. Those samples are to facilitate the study of wood decomposition and associated changes to the soil C pools. The experimental design facilitates the assessment of wood-soil food web, and it capitalizes on the strong foundation of research in the nationwide U.S. Department of Agriculture Forest Service (USDA-FS) Experimental Forest and Range Network.