Changes of soil particle composition and chemical characteristics after "returning farmland to lake" in the Dongting Lake area
退田还湖后洞庭湖区土壤颗粒组成和化学特性的变化

Long-term monitoring of soil characteristics is an important measure to evaluate the ecological consequences after implementation of the project of "returning farmland to lake (RFTL)".Three sites (Xiaojicheng, Guanyuan, and Qingshanyuan) which restored by three models of RFTL projects (poplar plantation, reed plantation, and natural restoration, respectively), were selected to study the changes of soil physical and chemical properties in comparison with counterpart agro-ecosystems after 8-year implementation of RFTL in the Dongting Lake area. Poplar plantation can facilitate the formation of clay and silt, and increase the contents of organic matter, total phosphorus, and total potassium in the Xiaojicheng. Soil physical characteristics was acclimated to that of natural ecosystem due to the influence of incessant flood in the Guanyuan where restored by reed plantation. Meanwhile, the content of organic matter decreased but total phosphorus increased in the Guanyuan. Soil particle composition and chemical characteristics were insignificantly different with that of agro-ecosystems in the Qingshanyuan, where natural lake was restored. Both biological characteristics of dominant species and the strength of natural processes are main factors accounting for the differences in soil characteristics in different restoration models of RFTL projects.