鄱阳湖湿地灰化薹草洲滩土壤微生物和酶特性对水分梯度的响应

Response of Properties of Soil Microbes and Enzymes in Beach Covered by Carex cinerascens in Poyang Lake Wetlands to Moisture Gradient

以鄱阳湖湿地灰化薹草(Carex cinerascens)洲滩表层土壤为研究材料,采用室内水分控制实验方法,设置不做任何处理的自然裸露、含水量保持在30%、放置在水面下10 cm和100 cm处4种不同水分梯度处理,土样经过42 d处理后,研究土壤微生物的生物量和土壤酶活性特征。研究结果表明,放置在水面下的土样的含水量、p H和总有机质含量都显著高于其它处理;含水量保持在30%的土样的微生物的生物量碳、氮含量分别最高,自然裸露处理下的最低;放置在水面下的土样的基础呼吸强度、乙酰氨基葡萄糖苷酶活性、磷酸酶活性、β-木糖苷酶活性、酚氧化酶活性和过氧化物酶活性都显著大于其它处理,且淹水深度对微生物的生物活性无显著影响。相关分析结果显示,影响灰化薹草洲滩表层土壤性质及其微生物和酶特性的主要因素是土壤含水量和有机质含量。

In this study, a simulation of moisture-control experiment was carried out to explore how soil microbial biomass and enzyme activities respond to different moisture gradient in Poyang Lake wetlands. The surface soil dominated by Carex cinerascens in the Poyang Lake wetlands was collected and treated with four different moisture gradient, including no treatment control, long-term wetting（30% water content）, 10 cm-flooded and 100 cm-flooded. The results showed that the soil physiochemical properties, enzyme activities as well as microbial biomass under different moisture gradient conditions were significantly different. The water content, p H and total organic matter of flooded soils were significantly higher than those of non-flooded treatment. The microbial biomass（carbon and nitrogen） of long-term wetting soil was the highest, followed by flooded soils, and no treatment control was the lowest. The respiration rate and the activities of acetylaminoglucosidase, phosphatase, β-xylosidase, phenol oxidase and peroxidase of flooded soil were significantly higher than those of non-flooded treatment. However, water depth had no significant impact on microbial activity.Principal component analysis showed that the main factors affecting the soil properties and microbial functional properties were soil moisture and organic matter. Our results suggested that the water level fluctuation of the Poyang Lake had a great impact on the biological activity of wetland soil. In particularly, the arid soil conditions significantly inhibit the growth and function of microbial community, while flooding conditions improve the p H of acidic wetland soil, promoting the total soil organic matter accumulation, and thus enhancing activities of soil enzymes.