基于GIS的上海崇明耕地土壤主要养分的空间变异研究

Study on Spatial Variability of Soil Nutrients in Chongming of Shanghai by Using GIS and Kriging Method

采用GIS与地统计学相结合的方法,对上海崇明表层土壤有机质(OM)、全氮(TN)、水解氮(AN)、速效磷(AP)、速效钾(AK)、阳离子交换容量(CEC)等的空间变异分布规律进行了详细的分析研究。研究中采用以最小块金效应法确定步长及相关参数,从而保证了进行筛选试验时理论插值模型的稳定性及其精度的可比性。结果表明,采样数据中,AK和CEC呈弱变异性, TN、AN、AP和OM含量呈中等强度变异性;除TN_S(S-小尺度,L-大尺度,下同)、AN_S及AK外,其他养分指标都呈明显的向异性:对偏基台值的比较分析发现,OM、TN_L、AN_L、AK、CEC的空间变异主要受大范围生态因素影响,其主变程基本大于10 km, TN_S、AN_S、AP受小范围生产因素影响,其变程小于5 km,且其中CEC的空间自关性较弱,TN较强,其余指标均为中等空间自相关;OM、AP变异函数的理论模型符合四球模型,AK、CEC符合球状模型,TN和AN均符合多尺度模型;其中TN_L采用孔穴效应模型、TN_S采用球状模型;AN_(L/S)均采用高斯模型;多尺度模型插值有效地调和了模型的宏观性和精确性;最终生成的养分含量分布图可直观反应它们的空间连续分布状态。

The spatial distributions of the main nutrients in the topsoil of Chongming Island in Shanghai are compreheasively explored in the research, including OM, TIN, AN, AP, AK and CEC, based on the combined method of GIS and geostatistics. The Principle of minimized Nugget Effect is used in test the lag as well as other related parameters, which can keep the stability of the interpolation models and the comparability of the precision tests. The result shows： according to the samples, AK and CEC distributed with a mild variation, while AN, TIN, AP and OM with an significant variation; by comparing the partial sill, the variation of OM, TNL （Large scale）, ANL, AK and CEC are mainly impacted by ecological factors at a large scale, with a range over 10 km on the whole, while TINS （Small scale）, ANS and AP by agricultural factors, with a range below 5 km; CEC bears an insignificant autocorelation, contrasting to the significant autocorelation of TN, and others bear moderate ones; tetra- spherical model is recognized as the most suitable model to OM and AP, spherical model to AK and CEC, and multi-scaled model to TN and AN （ to TN, hole effect model to the large scale and spherical model to the small scale; to AN, Gaussian model to both scales）; multi-scaled model adopted can harmonize the dilemma of global generalization and local accuracy; the maps of nutrients finally interpolated can illustrate the distribution of them in the continuity of the soil surface.