The Biochemical Characteristic Of Soil And Its Response To Human Disturbance In Woodland Of Harbin

Soil enzymes participate in many important biochemical processes carried out in soil ecosystems.Soil enzyme activities are sensitive indicators that are commonly used to characterize soil environmental quality and soil ecosystem changes.In the process of urbanization,with the change of land use type and utilization direction,the problem of soil environmental quality related to urbanization has become increasingly prominent.In this paper,several typical types of woodland in Harbin were studied,and the relationship between soil catalase,invertase,urease and phosphatase activity,soil physical and chemical properties and soil heavy metal content was studied.The variation of typical soil enzyme activity with woodland use type and human disturbance intensity and its main influencing factors.In addition,the path analysis method was used to explore the effects of soil physical and chemical factors and heavy metal content on soil enzyme activity,in order to clarify the role and effectiveness of soil enzyme activity in soil quality evaluation of urban woodland.Due to different management measures of different types of woodland,woodland may be disturbed by different human disturbances such as stamping and litter removal,soil structure is destroyed,nutrient conditions are changed,and soil enzyme activity is significantly changed.The soil catalase,urease and phosphatase activities of the park landscape forest were higher,and the soil invertase activity of the ecological public welfare forest was higher,while the overall soil enzyme activity of the university affiliated forest was lower.In different regions of the city,the activities of catalase and urease increased with the degree of urbanization,and the activity of invertase decreased with the deepening of urbanization,and the activity of phosphatase was not obvious.This indicates that soil catalase,invertase and urease activities are sensitive to woodland use types and human disturbance intensity responses.The results of soil physical and chemical properties analysis show that the soil compaction effect of urban woodland is significant,the bulk density is generally large,the soil is slightly alkaline,and the soil organic matter and effective nutrients have a certain spatial heterogeneity,and the content distribution is uneven,to a certain extent The strong influence of human disturbance on the soil.Correlation analysis showed that soil catalase activity was significantly positively correlated with pH,nitrate nitrogen and ammonium nitrogen(P<0.01);soil invertase activity was significantly correlated with soil water content(P<0.01),it was significantly positively correlated with soil organic matter and available phosphorus(P<0.05),and negatively correlated with soil pH,soil bulk density and nitrate nitrogen(P<0.05);soil urease activity and soil pH,nitrate state Nitrogen and ammonium nitrogen showed a very significant positive correlation(P<0.01).This indicates that soil enzyme activity is sensitive to changes in soil physical and chemical properties.The results of heavy metal content analysis in soil showed that the accumulation of heavy metals Cd,Pb,Cu and Zn in urban forest soils was more and more closely related to human disturbance.The content of soil was different by heavy metals.Correlation analysis showed that there was a significant positive correlation between soil catalase activity and soil Cd content(P<0.05).Soil invertase activity and soil Cd and Zn contents were significantly(P<0.01)and significant(P<0.05)Negative correlation;soil urease activity was significantly positively correlated with soil Pb content(P<0.01),and positively correlated with soil Cd and Zn(P<0.05).This indicates that heavy metal content has a certain influence on soil enzyme activity.According to the results of path analysis,nitrate content is the main influencing factor affecting soil catalase and urease activity.Zn content is the main influencing factor affecting soil invertase activity,and all of them are direct factors,and soil physical and chemical properties.The nature and changes in heavy metal content have a certain level of interpretation for changes in soil enzyme activity.This indicates that soil enzyme activity has a sensitive response to changes in soil physical and chemical properties and heavy metal content.However,it is known from the changes in phosphatase activity that enzyme activity has certain limitations on the response of human disturbance to soil.The sensitivity of the species to its response has an important impact,so the rational selection of soil enzyme species is of great significance for the enzymatic evaluation of soil quality.The urbanization process will cause human disturbance to the urban forest soil,and the soil physical and chemical properties and soil quality will change.The soil enzyme activity is sensitive to the physicochemical properties and heavy metal content changes.Therefore,the changes of soil enzyme activity are inseparable from human activities.Activity responds significantly to human disturbance.