Decomposition Rate of Organic Materials in the River Sediments and Its Relation to Vegetation, Sediment Respiration and Microbiomass in Sediments;pp. 171-183
Authors: (Akira Haraguchi, Chiharu Ikeda, Enen Ryu, Tsutomu Iyobe, The University of Kitakyushu, Japan)
Abstract: Decomposition of organic materials in river sediments is a key process in the matter cycle in a river ecosystem which includes river water, sediments and aquatic plants. We have made a preliminary survey on the decomposition rate of organic matter in river sediments using the litterbag method, as well as measurement of O2 consumption rate by microbial respiration and microbiomass in sediment under the three experimental conditions of vegetation in the Iwatakegawa river, dominated by a Phragmites japonica community: 1) with vegetation both above and below ground, 2) with vegetation below ground, and 3) without vegetation. The decomposition of Phragmites leaves and cellulose proceeded in the first three months. The decomposition rate of organic materials and O2 consumption rate by microbial respiration were not significantly different among the experimental vegetation conditions. The soil microbiomass-C and microbiomass-N were significantly different depending upon whether or not there was vegetation below ground. Thus we concluded that the decomposition rate of organic materials in river sediment was not affected by the presence of vegetation, although microbiomass in sediment increased with the presence of vegetation below ground.