Study On Soil Enzymes And Influencing Factors In Karst Forests Of Different Terrain In Maolan

Maolan karst forest is the only one with strong original nature in the same latitude area of the world.Compared with the normal landform forest,its landform is diverse,which leads to the specificity of the biogeochemical cycle of its ecosystem,which makes the soil enzyme activity and its influencing factors in Maolan karst forest different from other ecosystems.In order to understand the variation characteristics of soil enzyme activities in Karst forest under different terrains in Maolan,the relationship between soil enzyme activities and soil nutrients,litter nutrients and plant diversity was discussed,and the main factors affecting the changes of soil enzyme activities were analyzed.The activities of catalase,alkaline phosphatase,urease and sucrase in funnel,valley and hillside were selected as the research object.The results are as follows:1.Plant diversity: the top ten dominant species in the list of importance values were different among different terrains.The number of species,Shannon-Wiener diversity index,Margalef richness index,and Pielou evenness index were all higher in valleys than in funnel and hillside,while Simpson dominance index showed the highest value in hillside.Soil nutrients: Except for p H value and available potassium,the contents of soil nutrients were all higher in funnel than in valley and hillside,and there were significant differences among different terrains.Nutrient of litters: Litter contents varied greatly among different terrains.In addition to the total nitrogen content of litters,the nutrient contents of the other three litters were the lowest on the hillside.The nutrient content of litter in funnel and trough terrains was higher.2.Soil enzyme activities: the activities of catalase,alkaline phosphatase and sucrase were all higher in valley terrains than in funnel and hillside,while the urease activity showed the maximum in funnel terrains.The maximum activities of soil catalase,alkaline phosphatase and urease appeared in winter,and the soil sucrase activity in summer and autumn was greater than that in spring and winter.Catalase activity had little variation with seasonal change,while sucrase activity was more sensitive to seasonal change.3.The relationship between soil enzyme activities and soil nutrients in March 2019 in Maolan karst forest was studied by path analysis method.Results show that the four kinds of weak correlation between soil enzyme activity and soil nutrient,including hydrogen peroxide enzyme activity are the main factors influencing the total nitrogen and available nitrogen,alkaline phosphatase activity are the main influencing factors of available nitrogen and phosphorus,potassium urease activity of the main influence factors for phosphorus,potassium invertase activity is the main influence factors of total nitrogen and available potassium.The residual path coefficients of catalase,alkaline phosphatase,urease and sucrase activities were all large,indicating that the activities of the four soil enzymes may be affected by other factors that have not been considered.4.Redundancy analysis was used to analyze the environmental factors affecting soil enzyme activities.The results of redundancy analysis showed that the effects of plant diversity index and p H value on soil enzyme activities were greater than those of soil nutrients and litter nutrients.However,all the factors of influence studied in this project had a small total explanation for the activities of the four kinds of soil enzymes.T-value double-sequence diagram analysis showed that there were certain differences in the effects of single environmental factors on the activities of the four kinds of enzymes.This may be related to the different characteristics of soil enzymes,and soil enzyme activity is not affected by a single environmental factor,but the result of the comprehensive action of many environmental factors.