Forest Fragmentation Slows the Decomposition of Coarse Woody Debris in a Subtropical Forest

Forest fragmentation is increasing rapidly around the world, and edge effects caused by fragmented forests can influence ecosystem functions and ecological processes, including coarse woody debris (CWD) decomposition. Understanding the influencing mechanisms of edge effect on CWD decomposition is needed to assess the effects of forest fragmentation on carbon cycling and storage. We measured rates of mass loss of CWD of Cinnamomum camphora (L.) Presl. and Pinus taiwanensis Hayata over two years at two distances (0-5 m versus 60 m) from a forest edge at two altitudes (215 and 1,400 m a.s.l.), in a subtropical forest. In addition, we determined the microbial community of each CWD segment and the soil beneath via phospholipid fatty acids (PLFAs). Mass loss of CWD 60 m from the forest edge was 15% greater than that at the edge (0-5 m). Mass loss was positively correlated with the abundance of microbial and fauna community and moisture content of the decaying CWD. Distance from edge explained 17.4% of the total variation of the microbial abundance in CWD. The results indicate that the reduced abundance of microbial and fauna communities and moisture content at forest edges influenced rates of decomposition of CWD. Long-term experiments with more tree species and more forest types are needed to better assess edge effects generally. Study Implications: Forest fragmentation is increasing rapidly around the world, and edge effects caused by fragmented forests can influence ecosystem functions and ecological processes, including coarse woody debris (CWD) decomposition. Understanding the influencing mechanisms of edge effect on CWD decomposition is needed to assess the effects of forest fragmentation on carbon cycling and storage. The results of this study indicate that the reduced abundance of microbial and fauna communities and moisture content at forest edges reduced rates of decomposition of CWD. Long-term experiments with more tree species and more forest types are needed to assess the edge effect's generality.