关键词: 退耕还湖, 湿地土壤, 分形维数, 安庆

Abstract: Soils of recovered wetlands different in land use history(paddy and upland farming)and in mode(low dam and high net aquaculture in Baidang Lake and naturally recovered wetland in Caizi Lake)in Anqing were sampled for study of changes in fractal feature of soil particles after returning farmland to lake(RFL).Results show that in Baidang Lake area the fractal dimension of soil particles and the content of <0.01 mm particles decreased after RFL,and the change of the former was less significant in welands that used to be paddy fields than in wetlands that used to be upland fields,while in Caizi Lake area,the fractal dimension of soil particles and the content of <0.01 mm particles in creased after RFL,and the changes of the formaer was more significant in welands that used to be paddy fields than in wetlands that used to be upland fields.The fractal dimension of soil particles of the wetlands in these two areas were significantly and positively related to the contents of fine clay,coarse clay,and fine sit (P<0.01)and to the contens of soil organic matter,total P and available N(P<0.05),but negatively to the contents of coarse silt,fine sand and coarse sand (P<0.01).On the whole,the fractal dimension of soil particales of the wetlands is quite similar to the result of clustering analysis of soil nutrient contents.It is,therefore,suggested that fractal dimension of soil particles be used as a comprehensively quantitative index to evaluate changes in soil of the wetlands after RFL.

Key words: returning farmland to lake, wetland soil, fractal dimension of soil particle, Anqing