The Activities Of Soil Enzyme In Riparian Of The Lijiang River

Riparian ecotones as the sinks, sources or transformers of soil organic matter contained the interference from uplands, lowlands and aquatic zone, played a critical role in regulating the components of chemical composition between terrestrial and aquatic zone.The partial involvement of soil enzymes throughout the process of soil organic matter decomposition and synthesis has influenced all the biochemical reactions of soil, directly or indirectly, and has had a great impact on material circulation within the ecological system. Riparian ecotones have different gradients, complicacy of the variation of soil properties aggravated by periodic flooding conditions. In the riparian ecotones of the Lijiang River, soil water-soluble chemical composition, four kinds of soil hydrolyses namely glycosidase, chitinase, leucine aminopeptidase and phosphatase, and two kinds of oxidoreductase such as phenol oxidase and peroxidase weremeasured under three kinds of gradients, meanwhile the relationship between the soil properties and enzyme activities was studied through field investigation and lab analysis. The study not only had theoretical significance in exploring the transformation process of soil nutrient in Lijiang river, but also provide basic data for the ecological restoration on the coast of the Lijiang river.(1)The result showed that the activities of soil chitinase and alcaline phosphates were the highest under the close-water area and the lowest under the area far away from water. Soil phenol oxidase and peroxide activities were the highest in the areas far away from water, and the lowest under the close-water area. The activities of soil glycosidase and leucine aminopeptidase showed the highest level in the areas moderate distance away from water and the lowest under the area far away from water. Soil water content was positively related to the activities of chitinase and alcaline phosphates. The organic carbon content is positively related to the activities of leucine aminopeptidase. Soil dissolved organic carbon nitrogen showed significantly relation with soil glycosidase and alcaline phosphates. The activity of soil chitinase were negatively associated with soil dissolved organic nitrogen.(2) The results showed that the activities of soil glycosidase and phenol oxidase under mosses were significantly higher than that under herbaceous and shrubs, soil glucosaminidase activity under shrubs was significantly higher than that under mosses and herbs, peroxides activity under herbs was significantly higher than that under mosses and shrubs, whereas the activity of leucine amino peptidase has no obvious difference among three vegetation types. Among the six enzyme activities examined, soil water content was positively related to the activities of glucosidase and phenol oxidase, and negatively related to the activities of glucosaminidase and alcaline phosphates. Soil organic carbon and readily oxidizable carbon were negatively associated with glucosidase and phenol oxidase, and were positively with glucosaminidase. Soil dissolved organic carbon were positively related to the activities of glucosidase as well as phenol oxidase.In short, the activities of soil chitinase and alcaline phosphate were the highest in the gradient that close to the river, the activites of soil glucosidase and leucine aminopeptidase were the highest under the gradient moderate distance away from water, soil phenol oxidase and peroxide activities were the highest in the gradients far away from water. There were differences between different kinds of-soil enzymes under different vegetation types in riparian ecotones, and soil water content and soil organic carbon influenced the change of soil enzyme activities significantly.