Characteristics Of C N P In Soils Of Chengdu Urban Green Space And Its Spatial Variability

With changeing in urban land use patterns will affect soil structure,quality,nutrient cycling and function in urban ecosystems,and thus affect urban ecological environment.Urban green space plays a key role in protecting biodiversity and water resources,improving microclimate,and isolating urban pollution.However,the research on urban green space ecosystem has yet to be deepened.In this study,the green soil in the downtown area of Chengdu was selected as the research object.Through sampling and indoor analysis of different types of green space,the content and spatial variability of C N P in green space were analyzed with the support of GS+ and ArcGIS10.0.The effects of urbanization factors such as green age,distance from urban center and building density on soil carbon,nitrogen and phosphorus contents in green space.The main findings are as follows:(1)The alkaline soil of Chengdu green soil belongs to the alkaline soil,The average organic carbon content is 15.69g/kg,the alkali nitrogen content is 68.66mg/kg,the total nitrogen content is 1.48g/kg,and the effective phosphorus content is 27.57mg/kg,the total phosphorus content is 0.82g/kg;The coefficients of variation were: 44.87%,41.27%,53.34%,3.55%,and 97.74%,respectively.There is a very significant positive correlation between carbon,nitrogen and phosphorus.Organic carbon,alkaline nitrogen and available phosphorus have strong spatial correlation;total phosphorus content has moderate spatial correlation;total nitrogen content is less spatially dependent.(2)The soil organic carbon content of urban greenbelt soil in shelterbelt green space was significantly higher than that of the other four types of green space soil;The total nitrogen content was the highest in shelterbelt,the transportation green space was the lowest,and the total nitrogen content showed no significant difference under various green land types;The content of alkali nitrogen in the surface soil of different green land types was significantly different.The contents of total nitrogen and alkali nitrogen in the shelterbelt green space were significantly higher than those in other green areas,and the soil content of transportation green space was the lowest;The mean values of totalphosphorus and available phosphorus in surface soils of different green land types were significantly different.The soil total phosphorus content in park green space was the highest,and the available phosphorus content in residential green space was significantly higher than other green land types.(3)The C N P in the green space of the study area showed a significant positive correlation with the green field age.With the passage of time,soil organic carbon,total nitrogen,alkali nitrogen,total phosphorus and available phosphorus firstly showed an increasing trend.After the soil-forming conditions were relatively stable,the soil properties tended to be stable,and the green space stopped for a long period of time.After the protection,the carbon,nitrogen and phosphorus content decreased.(4)Correlation analysis showed that there was a significant negative correlation between the distance from urban center and C N P.The carbon,nitrogen and phosphorus content decreased with the distance from the city center.The phosphorus content of green soil soil is twice that of the suburbs.(5)Correlation analysis between the building density in the sample buffer and the carbon,phosphorus and phosphorus contents in the sample soil showed that the correlation between soil organic carbon,total nitrogen and alkali nitrogen in the surface soil was lower than that in the building density,and the total phosphorus and available phosphorus content were both low.There is a significant positive correlation with building density.