苏北大丰生态工程区两种植物群落土壤酶活性比较

土壤酶在土壤生态系统的物质循环和能量流动方面扮演着重要的角色.研究了大丰海滨湿地中实施微地貌水文饰变生态工程后的芦苇群落和互花米草群落土壤磷酸酶、脲酶和过氧化氢酶的季节变化动态,并对两种群落的3种土壤酶活性与各理化因子之间作了相关性分析,结果表明:(1)芦苇群落和互花米草群落土壤中磷酸酶活性季节变化动态均为单峰型曲线,过氧化氢酶活性均为单谷型曲线,最大值和最小值都出现在夏季(8月份),土壤脲酶活性季节变化规律不明显.(2)相关分析表明,互花米草群落土壤磷酸酶活性与土壤含盐量、植物生物量显著相关,而其过氧化氢酶活性与二者呈显著负相关;芦苇群落土壤磷酸酶活性与有机质和速效磷含量呈显著正相关,过氧化氢酶活性则与二者均呈显著负相关.此外,两种群落中的土壤脲酶活性与所测土壤理化因子均无明显相关关系.(3)两种植物群落中土壤酶活性受土壤理化因子的共同影响.通径分析表明,在互花米草群落中,各因子对磷酸酶活性的影响程度依次为:土壤含盐量＞速效钾＞速效磷＞有机质＞铵态氮;对脲酶活性的影响程度依次为:有机质＞速效钾＞速效磷＞土壤含盐量＞铵态氮;对过氧化氢酶活性的影响程度为:速效钾＞土壤含盐量＞有机质＞速效磷＞铵态氮.在芦苇群落中,各因子对磷酸酶活性的影响程度依次为:速效磷＞土壤含盐量＞有机质＞铵态氮＞速效钾;对脲酶活性的影响程度依次为:有机质＞速效钾＞土壤含盐量＞铵态氮＞速效磷;对过氧化氢酶活性的影响程度为:铵态氮＞速效钾＞土壤含盐量＞速效磷＞有机质.(4)微地貌水文饰变生态工程在一定程度上改良了土壤,有利于实现芦苇对互花米草的替代.

Comparative studies on the soil enzymic activities of two plant communities in Dafeng ecological engineering wetland of Northern Jiangsu

Soil enzyme plays an active role in the material circulation and energy flow of soil biochemical process. This article deals with the seasonal change of soil enzyme activities of phosphatase, urease and catalase in Phragmites communis and Spartina alterniflora communities in Dafeng coastal wetland after carrying out the eco-engineering with hydro-geomorphological modification. Meanwhile the relationship between the soil enzymic activitives and physical-chemical factors is discussed by correlation analysis. The results showed :(1) The seasonal variation curves of the soil phosphatase activity in two communities were all "single peak curves", while the soil catalase activity in two communities were all "single valley curves". The maximal soil phosphatase activity values and the minimum soil catalase activity values of both communities all appeared in summer (August). However, the soil urease activities of two communities changed erratically within a year. (2) The result from the correlation analysis showed there was significant positive correlation between the soil phosphatase activities and soil salinity, community biomass in Spartina alterniflora communities, while the correlation analysis between the soil catalase activities and two physical-chemical factors was vice versa. In Phragmites communis communities, the soil phosphatase activities had a significant positive correlation with organic matter and available P, while the soil catalase activities was vice versa. There was no correlation between the soil urease activities and all physical-chemical factors in both communities.(3) Path analysis between soil enzyme activities and soil phy-chemical factors showed that soil enzyme activities were the result of interactions among soil phy-chemical factors,and each factor acted differently in the two communities. In the S.alterniflora community, soil phy-chemical factors affecting phosphatase activity, urease activity and catalase activity decreased in the orders of soil salinity＞available K＞available P＞O.M.＞ammoniacal N, O.M. ＞available K＞available P＞soil salinity＞ammoniacal N and available K＞soil salinity＞O.M. ＞available P＞ammoniacal N. In the P.communis community, the orders were available P＞soil salinity＞O.M.＞ammoniacal N＞available K, O.M.＞available K＞soil salinity＞ammoniacal N＞available P and ammoniacal N＞available K＞soil salinity＞available P＞O.M..(4) The eco-engineering of hydro-geomorphological modification meliorated the coastal wetland soil to some extent, and it was propitious to substitute Phragmites communis community for Spartina alterniflora community.