Developing a Large Woody Debris Budget for the Lower San Antonio River

Large woody debris (LWD) and woody debris jams are important components to the aquatic ecosystem of rivers and streams throughout the United States, but only relatively recently has their importance been recognized. Factors influencing input, export, and decay of LWD in rivers are not clearly understood in the southeastern United States. Under natural conditions it is believed that a natural balance of import and export would exist over the long term; however, it is not known to what extent management has affected LWD dynamics.;This study evaluates the dynamics of import and export of LWD into the Lower San Antonio River located in Texas at six sampling sites. The data collected were used to develop a LWD budget, which is current estimates of input rates, retention rates, and export rates for LWD. The data collected and analyzed in this study represented the current land use and streamflow conditions in the river.;The Lower San Antonio River was found to be supply limited for LWD and instream mobility of LWD is very high leading to large quantities of wood moving downstream during high flow events. The high mobility of LWD allows for major upstream tributaries to contribute LWD into the system. Protection of riparian forests upstream is important to maintaining LWD dynamics and should include maintaining a forested buffer along the river and the major tributaries.