Study On Soil Organic Carbon Mineralization Of Park Green Space In Different Vegetation Types And Years Of Planting In Chengdu

Global warming has attracted the attention of scholars and has become a hot topic in academic research.One of the main contributors to climate warming was carbon dioxide,and urban ecosystems contributed 80%of global carbon dioxide emissions.Urban green space soil has the function of purifying air,regulating regional microclimate,and balancing urban carbon and oxygen.Therefore,the change of soil carbon pool in green space was of great significance to the carbon and oxygen balance of urban ecosystem.However,strong human disturbance and complex environment will affect the carbon cycle and carbon sequestration capacity of greenbelt soils,thus affecting the carbon and oxygen balance of urban ecosystems.At present,there was still a lack of research in this area.This study was based on three different planting years?5,10,15 years?in Chengdu,and selected three main vegetation types?deciduous trees,evergreen trees,lawns?soil,studied on organic carbon mineralization and its relationship with physical and chemical properties and enzyme activity.In order to provide basic information and reference for understanding the impact of human activities on the carbon cycle and the construction of organic carbon mineralization models.The results were as follows:?1?The effects of vegetation differences on physicochemical properties,enzyme activities and active organic carbon components were weak.Amylase,polyphenol oxidase,peroxidase activity and carbon pool activity were higher in turf vegetation soil,1.04-3.34times of two kinds of arbor vegetation.Vegetation age significantly affected soil nutrients.With the increase of planting years,soil pH gradually decreased,TN and TP were significantly concentrated,enzyme activity,active organic carbon content and carbon pool activity decreased.And amylase,sucrase,peroxidase and polyphenol oxidase were significantly positively correlated with WSOC,MBC and ROC,and the correlation coefficient was the highest?0.923?.?2?The soil organic carbon mineralization in the green space of Chengdu park has a phased feature.The first to seventh days were the rapid mineralization stage,and the daily average mineralization reaches the peak on the first day of culture?30.54-282.50 mg/kg?.On the 7th day,only 20.40%-51.44%of the first day.The 7th to 35th days were the slow mineralization stage.The mineralization intensity is the highest?3.33%-9.66%?of the turf vegetation planted for 5 years.With the mineralization process,the soil WSOC,MBC and ROC content fluctuated,and WSOC contributed the most to the cumulative mineralization,which was 33.06%-45.18%.The average daily mineralization,cumulative mineralization and mineralization intensity were all characterized by 35°C>25°C>15°C,and the Q₁₀ was not significant under different vegetation types.The first-order kinetic equation has a good effect on soil organic carbon dynamics at three temperatures.The planting age was lower and the Cp and Cp/SOC values of the single turf vegetation were higher,and the soil carbon mineralization potential was also higher.?3?Soil organic carbon mineralization was significantly positively correlated with pH,amylase,sucrase,polyphenol oxidase,peroxidase and WSOC,MBC,ROC.The long-term addition of exogenous N and P leads to the accumulation of nutrients while inhibiting mineralization.