Effects of Poplar Plantations on Soil Physical and Chemical Characteristics in Dongting Lake Wetlands

In recent decades, large-scale poplar plantations have caused great concerns about their negative effects on ecological environments in the Dongting Lake wetlands. In this paper, five and eleven years of poplars were chose to study the effects of poplar plantation on soil physical and chemical characteristics in comparison with adjacent Miscanthus sacchariflorus, an indigenous vegetation of the Dongting Lake. For soil physical properties, soil water content was lowest in M. sacchariflorus and highest in 11-year poplars. Poplar plantation changed soil particle-size distribution and decreased the percentage of clay and silt but increased that of sand. The increased percentage of sandy was increased with increased stand age. For soil chemical properties, poplar plantation decreased electrical conductivity in middle soil (20-60 cm), total potassium in all layers of soil, but increased pH in subsoil (60-100 cm). There was no difference in phosphorus among three vegetations. Additionally, poplar plantations also decreased total nitrogen in soil layer of 40-60 cm, and the effect was increased with increased stand age. Finally, both poplars have different effects on total carbon, resulting in a lower carbon in 5-year poplars but a higher in 11-year poplars compared to M. sacchariflorus. Therefore, the changes of soil properties in poplar plantation would have further effects on wetland ecosystems.