合肥老城区绿地土壤pH和氮磷的空间变异特征

SPATIAL VARIABILITY OF SOIL PH,NITROGEN AND PHOSPHORUS OF URBAN GREENLAND IN CENTRAL HEFEI

基于地统计学和GIS方法研究了合肥主城区一环内绿地表层土壤（0-10cm）的pH值和全氮、速效磷、全磷3种养分要素的空间变异特征,并应用半变异函数分析了pH和各养分要素的空间异质性程度。结果表明：土壤pH变化范围和变异系数分别为6.7-8.8和5.0%,全氮分别为292-3 789mg/kg和47.5%,全磷为147-2 470mg/kg和68.7%,速效磷为5.6-106.4mg/kg和65.7%;全磷含量的变异系数最大,其空间异质性主要由结构性因素引起,pH、全氮和速效磷的空间变异则由随机性因素和结构性因素共同作用引起。土壤全氮与pH之间存在显著负相关,而土壤全磷与速效磷存在显著正相关。pH和速效磷的最佳拟合模型为球状模型,全氮和全磷的最佳拟合模型为指数模型;通过Kriging插值得到合肥市一环内土壤pH和各养分的空间分布特征。

Urbanization is increasing worldwide and impacting native ecosystems through disturbance, climatic modification, and pollutant deposition. In order to better understand and quantify the potential effects of human activities on soil properties and its spatial pattern in urban ecosystems, the contents and spatial distribution of pH, total nitrogen （TN）, total phosphorus （TP） and available phosphorus （AP） in the surface soils （0-10 cm） of urban green-land were studied in central Hefei using GIS technology and geo-statistical analysis. A total of 105 sites was sampled over 20 km^2 in central Hefei. The results showed that the soil pH was within a range of 6.7 to 8.8 with a coefficient of variation （CV） of 5.0%. The concentrations of TN ranged from 292 to 3 789 mg/kg with CV of 47.5%. The TP concentrations were from 147 to 2 470 mg/kg with CV of 68.7% and AP were 5.6-106.4 mg/kg with CV of 65.7%. The theoretical semivariogram models for soil pH and AP were best fitted by the spherical model, while for TN and TP were best fitted by the exponential model. The spatial variability of TP was mainly resulted from structural factors, and had high spatial correlation. However, the spatial variability of soil pH, TN and AP was caused by both random factors and structural factors. The spatial correlation for soil pH, TN and AP was moderate. In addition, soil total N was significantly and positively correlated with pH. Soil available P was significantly and positively correlated with total P. The spatial distributions of soil pH, TN, TP and AP in urban Hefei were analyzed by the Kriging interpolation method.