Soil Fauna Abundance, Feeding and Decomposition in Different Reclaimed and Natural Sites in the Sanjiang Plain Wetland, Northeast China

We investigated the effects of anthropogenic land change on soil fauna density, decomposition and feeding activity in five natural and reclaimed sites of the Sanjiang Plain, China. During the past 60 years, much of the land was converted from forests and wetlands to reclaimed agricultural land use areas. The highest feeding activity and mesofauna density, dominated by springtails, oribatid/gamasid mites and proturans, was found in the wetland site followed by a plantation forest and a secondary island forest. By contrast, two reclaimed soybean fields had significantly lower mesofauna densities and reduced feeding activities in the first six centimeters of the topsoil. The decomposition process after 60 days in these agricultural sites showed decreased values for mesofauna and microorganisms with increasing land use. The loss of functional guilds for the secondary decomposition process could explain the need for increasing fertilization to reach the same yield in the reclaimed soybean fields of this region. This investigation further underlines the outstanding role of the remaining fragmented wetland sites as a mesofauna biodiversity refugium and the importance of these communities in the feeding and decomposition processes in such ecosystems.