退耕还湖后菜子湖湿地土壤理化性质及微生物量变化

以不同退耕年限下菜子湖湿地土壤和邻近原始湿地及仍耕作油菜地为研究对象，分析退耕还湖后土壤理化性质和微生物量碳氮变化。研究结果表明：随着退耕还湖年限增加，土壤容重逐渐降低，土壤含水量和粘粒含量逐渐增加，土壤有机质和全氮含量逐渐增加，而土壤全磷含量降低；表层土壤微生物量碳含量为33377~70075mg/kg，表层土壤微生物量氮含量为3080~6401 mg/kg，且均有退耕还湖后升高趋势；土壤微生物量碳与土壤有机质、全氮、pH呈极显著相关（P<001），与土壤粘粒含量显著相关（P<005）；土壤微生物量氮与土壤有机质、全氮、容重呈极显著相关（P<001），与pH显著相关（P<005）。分析表明，退耕还湖后随着人类活动干扰压力的减弱和湿地水文条件的恢复，自然植被也逐渐恢复，土壤理化性质朝原始湿地方向改善，促使土壤微生物量升高，但总体仍未达到原始湿地状况

CHANGES OF SOIL PHYSICAL AND CHEMICAL PROPERTIES AND #br# MICROBIAL BIOMASS IN WETLANDS RETURNING FARMLAND #br# TO LAKE IN THE CAIZI LAKE，ANHUI PROVINCE

Soils were sampled in rape field， native wetlands， and wetlands returning from farmland to lake within different periods （3， 7， 9， 11 and 21 years） to analyze changes of soil physicochemical properties and microbial biomass carbon and nitrogen The results showed that soil bulk density decreased with the increase of periods since farming abandoned For example， the soil bulk density in abandoned farmland within 3 years was 151 g/cm3 while that in abandoned farmland within 21 years was 079 g/cm3. Soil moisture and clay content increased gradually with abandoning period， moreover the water content of abandoned farmland in 21 years was 2100% higher than that of rape field， and 687% higher than that of 3 years abandoned farmland. The clay content of 21 years abandoned farmland was 258% higher than that of rape field， and 434% higher than that of 3 years abandoned farmland. Soil organic matter and total nitrogen content increased gradually， such as the soil organic matter content of 3 years abandoned farmland being 2124 g/kg and that of abandoned farmland in 21 years being 5266 g/kg. The total nitrogen content of abandoned farmland in 3 years being 105 g/kg and 11 years abandoned farmland being 252 g/kg The total phosphorus reduced with the increase of farming abandoned periods， such as that in 3 years abandoned farmland being 054 g/kg and that in 21 years abandoned farmland being 040 g/kg. The soil microbial biomass carbon content range was 33377-70075 mg/kg，while the soil microbial biomass nitrogen range was 3080-6401 mg/kg Soil microbial biomass carbon was highly significantly correlated （P<001） with soil organic matter， total nitrogen and pH， and was significantly correlated （P<005） with the soil clay content. The soil microbial biomass nitrogen was highly significantly correlated （P<001） with soil organic matter， total nitrogen and bulk density， and was significantly correlated （P<005） with soil pH The analyses and discussion of results indicated that with the hydrological regime and vegetation condition of wetland recovering after farmland abandoning， the soil physicochemical properties were improved towards the native wetland， which promoted soil microbial biomass carbon and nitrogen increasing， but had not reached native wetland condition yet