DECOMPOSITION OF SILVER MAPLE (ACER-SACCHARINUM L) WOODY DEBRIS IN A CENTRAL ILLINOIS BOTTOMLAND FOREST

The decomposition rate of silver maple (Acer saccharinum) woody debris was measured in a seasonally flooded mature wetland forest in central Illinois. Small diameter woody debris logs (5-cm diameter x 0.75-m long) of three successive decomposition classes (fresh, intermediate, and rotten) were placed in the floodplain for a period of 1.5 years. By incorporating a chronosequential design that extended the time frame to about 3.5 yr, the decomposition coefficient (k) of sample logs was estimated at 0.089 yr(-1) with a half-life of 7.8 years. Mass loss by microbial activity and leaching was estimated at 90%, whereas fragmentation accounted for 10%. Nutrient analysis of the logs indicated that P and K seemed to be released, whereas N, Ca, and Mg were immobilized. Overall, Ca and N were found in significantly higher concentrations than other nutrients (Ca>N>>K>Mg>P). Because small diameter woody debris has limited quantities of nutrients and a long residence time, its role in this mature forested wetland does not seem to be a nutrient reservoir but rather a long-term organic matter storage pool.