Spatial Pattern Of Soil Nutrients In Longquanshan Urban Forest Park,Chengdu

This study,supported by the research project on the relationship between the ecological protection system of Longquanshan Urban Forest Park and the area of Chengdu Longquanshan Urban Forest Park,designed 297 sampling points with a grid of 2 km x 2 km,and used the support of Arc GIS,GS and other related software platforms,based on the soil pH and organic matter,alkali deoxidizing nitrogen,quickacting potassium,and effective phosphorus.The basic characteristics of soil nutrients in Longquanshan Urban Forest Park are analyzed,and the characteristics and distribution of soil nutrient space structure in Longquanshan Urban Forest Park are analyzed,so as to provide basic theory and scientific guidance for the selection and matching of tree species and sustainable use of land in the construction of Longquanmountain Urban Forest Park.The research of the thesis has mainly achieved the following results and understanding:(1)The content of soil organic matter(SOM)varies from 3.4 to 52.88 g / kg,with an average value of 17.89 g / kg,and the whole belongs to the fourth grade;the content of soil alkaline nitrogen(AN)varies from 1.25 to 147.21 mg / kg,the average 70.79 mg / kg,the whole belongs to the third grade;the soil available potassium(AK)content varies from 5.42 to 337.32 mg / kg,the average value is 66.16 mg / kg,the whole belongs to the fourth grade;the soil available phosphorus(AP)content changes The range is 2.37 ? 63.61 mg / kg,the average value is 22.39 mg / kg,the whole belongs to the second grade;the soil pH value is between 4.30 ? 8.80,the average value is 6.41,and the whole is slightly acidic.The coefficient of variation of soil pH is low,only 8.71%,showing weak variability.The coefficients of variation of soil alkaline nitrogen(AN),soil available phosphorus(AP),soil available potassium(AK)and soil organic matter(SOM)It was 43.07%,77.40%,83.79%,58.08%,all showed moderate variability.(2)The best fitting models of soil nutrients in the study area are exponential models.The nugget coefficients of soil AN and pH are 13.98% and 12.18%,respectively,and their spatial correlations are significant.The soil SOM,AK,and AP The nugget coefficients are 53.50%,49.81% and 36.33%,respectively,and the degree of spatial correlation is medium.The fractal dimension of pH and four soil nutrients varied from 1.957 to 1.969,and the spatial heterogeneity from large to small was: AN> pH> AK> AP> SOM.Analysis of spatial autocorrelation found that only the organic matter z value is greater than 1.96,showing significant spatial aggregation characteristics,and the scores of the remaining four elements are less than 1.96,indicating that the spatial aggregation is not significant.(3)Using Kriging interpolation and soil nutrient grading to obtain different soil nutrient spatial distribution maps,the analysis shows that the distribution pattern of alkali-decomposed nitrogen is more complex,the distribution of high and low content values is more scattered,broken patches,weak regularity;effective phosphorus content The grades are staggered in the region,showing a spatial distribution pattern of local blocks in space;the spatial distribution of available potassium is more obvious,the overall is slightly lower in the north-south central part,the distribution is more continuous in the southern and northern regions,and the patch in the central region is more Fragmentation,mainly in the form of dots or sporadic distribution;the distribution of organic matter is slightly higher in the north and the middle,and lower in the south;the soil pH shows a spatial pattern of overall bands and local blocks,and the overall acidity is slightly acidic.