RETENTION OF COARSE ORGANIC PARTICLES IN STREAMS IN THE SOUTHERN APPALACHIAN MOUNTAINS

Retention of coarse particulate organic matter (CPOM) is essential to the efficient use of organic matter in streams supported by allochthonous inputs. To measure retention and to study factors affecting retention, we conducted both long-term and short-term experiments using small dowels as indices of stick retention and pieces of paper as indices of leaf retention. These experiments were done in streams at Coweeta Hydrologic Laboratory. In general, we found that both types of CPOM were efficiently retained in all streams. Factors that affected CPOM transport and retention were storms, stream size, stream depth, and the abundance of retention structures in the streams. After initial transport, woody CPOM was transported only during storms. Retention was greater in smaller streams and in shallower stream sites. Rocks, boulders, and woody debris were the most important retention structures. In the stream draining a logged catchment, lower CPOM retention was associated with lower abundance of woody debris dams.