安庆沿江退耕还湖18年的湿地土壤生物化学性质研究

以安庆沿江农田不同退耕还湖方式——低坝高网式水产养殖和湿地自然恢复区的湿地土壤为研究对象,并以邻近的水田和旱地土壤作为参照,研究退耕还湖后湿地土壤生物化学性质变化.结果表明,退耕还湖18a(1991～2009年)后,在湿地自然恢复区,湿地土壤(深度为0～30 cm)微生物量碳含量、土壤磷酸酶活性和过氧化氢酶活性增大,土壤脲酶活性和蔗糖酶活性减小;由水田退耕18a的湿地亚表层土壤(深度为15～30 cm)脲酶活性和表层土壤(深度为0～15 cm)过氧化氢酶活性与由旱地退耕18a的湿地无明显差异,由水田退耕18a的湿地表层土壤脲酶活性和亚表层土壤过氧化氢酶活性、表层和亚表层土壤微生物量碳含量、蔗糖酶活性和磷酸酶活性都明显高于由旱地退耕18a的湿地.退耕还湖18a后,进行低坝高网式水产养殖的湿地土壤微生物量碳含量、土壤脲酶活性、蔗糖酶活性和磷酸酶活性减小,而过氧化氢酶活性增大;由水田退耕18a的湿地表层和亚表层土壤微生物量碳含量与由旱地退耕18a的湿地无明显差异,由水田退耕18a的湿地表层和亚表层土壤脲酶活性、表层土壤蔗糖酶活性和亚表层土壤磷酸酶活性明显高于由旱地退耕18a的湿地,而其亚表层土壤蔗糖酶、表层土壤磷酸酶、表层和亚表层土壤过氧化氢酶活性均显著低于由旱地退耕18a的湿地.天然湿地土壤微生物量碳含量、土壤脲酶活性、蔗糖酶活性和磷酸酶活性明显低于已退耕还湖的湿地和参照农田土壤.退耕还湖后,湿地的不同利用方式及其历史利用方式影响湿地土壤生物化学性质;湿地土壤有机质等养分含量和水文条件变化是导致湿地土壤生物化学性质变化的主要原因.

Biochemical Properties of Soils in Wetlands of Returning Farmland to Lake for 18 Years along the Yangtze River in Anqing

Soils from wetlands with different historical land use patterns(hydroponic farming and dry farming) and returning under different restoration modes(low dam and high net for aquaculture,such as Baidang Lake area,and natural ecology restoration of wetland,such as Caizi Lake area) were sampled to reveal changes of soil biochemical properties after returning farmland to lake(RFL) along the Yangtze River in Anqing.The results showed that the amounts of soil microbial biomass carbon and the activities of soil phosphatase and catalase increased,however,the activities of soil saccharase and urease decreased after RFL in Caizi Lake area;no significant difference was found between urease activities in sub-surface soils and catalase activities in surface soils from wetlands with historical hydroponic farming(HHF) and those in wetlands with historical dry framing(HDF) after 18-year RFL,while soil urease activities in surface soils and catalase activities in subsurface soils,amounts of soil microbial biomass carbon,saccharase and phosphstase activities both in surface and sub-surface soils were significantly higher in wetlands with HHF than those in wetlands with HDF after 18-year RFL in Caizi Lake area;the amounts of soil microbial biomass carbon and the activities of soil saccharase,urease and phosphstase decreased,while the activities of soil catalase increased after 18-year RFL in Baidang Lake area;no significant difference was found between microbial biomass carbon amounts both in surface and subsurface soils from wetlands with HHF and those in wetlands with HDF,while urease activities both in surface and subsurface soils,saccharase activities in surface soils,and phosphatase activities in subsurface soils were significantly higher in wetlands with HHF than those in wetlands with HDF after 18-year RFL in Baidang Lake area;saccharase activities in subsurface soils,and phosphatase activities in surface soils,and catalase activities both in surface and subsurface soils were significantly lower in wetlands with HHF thanthose in wetlands with HDF after 18-year RFL in Baidang Lake area;the amounts of soil biomass carbon and the activities of urease,saccharase,and phosphatase in semi-natural wetlands were lower than those in most of other sampling ecotesseras in the same lake area.