多种两步模式的三维制图方式在丘陵区林地土壤有机碳预测中的对比  

Comparison of Different Two-Step Models of Three-Dimensional Mapping Approaches for Soil Organic Carbon Prediction in Hilly Woodlands

作　　者：杨华蕾 王晓晴 张美薇 郭倩 王会利[2] 曾令涛 崔宇培 孙孝林[1] YANG Hualei;WANG Xiaoqing;ZHANG Meiwei;GUO Qian;WANG Huili;ZENG Lingtao;CUI Yupei;SUN Xiaolin(School of Geography and Planning,Sun Yat-sen University,Guangzhou 510006,China;Guangxi Forestry Research Institute,Nanning 530002,China)

机构地区：[1]中山大学地理科学与规划学院,广州510006 [2]广西壮族自治区林业科学研究院,南宁530002

出　　处：《水土保持学报》2024年第2期351-363,共13页Journal of Soil and Water Conservation

基　　金：国家自然科学基金项目(42071062,41771246)。

摘　　要：[目的]为了探讨多种两步模式三维制图方法的准确度影响因素及其规律。[方法]以华南典型丘陵区1个面积约5 km^(2)的林场内土壤有机碳为研究对象,分别使用样条函数、指数函数和幂函数作为深度函数,普通克里格和随机森林作为水平制图方法,以及两步模式的2种不同制图形式(称为形式A和B),进行土壤有机碳含量的三维预测制图,并探究不同的深度函数、水平制图方法或制图形式对两步模式三维制图结果的影响规律。[结果](1)深度函数在很大程度上决定制图结果在垂直和水平方向上的变异,表现在制图结果的变异在3个深度函数之间差异较大,其中指数函数上的变异最大,幂函数上最弱,而水平制图方法(普通克里格与随机森林)对制图结果的垂直变异影响不大,但对表层的空间变异影响较大;(2)样条函数由于模拟的深度曲线与实测点吻合得最好,因而准确度最好,表现在基于样条函数的三维制图一致性相关系数(CCC)为0.72~0.75,均高于同种制图形式下的其他函数(CCC为0.64~0.74),而水平制图方法中普通克里格的制图效果好于随机森林,表现在前者的CCC为0.67~0.75,后者的CCC为0.64~0.72;(3)两步模式的2种制图形式对准确度的影响较小,仅在底层的准确度上表现出形式A(即水平预测制图深度函数模拟值)好于形式B(即水平预测制图深度函数参数);(4)所有制图方式中,普通克里格与样条函数相结合的制图形式A的准确度最高,决定系数(R 2)达0.76,一致性相关系数(CCC)为0.75,均方根误差(RMSE)为3.50 g/kg。[结论]在两步模式的三维土壤制图中,首先应考虑样条函数作为深度函数,其次依据研究区的景观条件和样本量,考虑水平制图方法,最后,尽量采用两步模式的第一种制图形式。[Objective]In order to investigate the influencing factors and variation rules of accuracy of various two-step models of 3D mapping methods.[Methods]Soil organic carbon in a forest with an area of about 5 km 2 in a typical hilly region of South China was mapped.Spline functions,exponential functions and power functions were used as depth functions,ordinary kriging and random forest were used as horizontal mapping methods and two different mapping forms(called forms A and B)were used.The 3D prediction mapping of soil organic carbon was carried out,and the influence of different depth functions,horizontal mapping methods and mapping forms on the 3D mapping results of two-step model was explored.[Results](1)The depth function largely determined the variation of mapping results in vertical and horizontal directions,which showed that the variation of the mapping results was significantly different among the three depth functions.Exponential function had the largest variation and power function had the weakest variation,while horizontal mapping methods(ie.ordinary kriging and random forest)had little influence on the vertical variation of mapping results.However,the spatial variation of surface layer was greatly affected by the horizontal mapping methods.(2)The accuracy of spline function was the best because the simulated depth curve was in the best agreement with the measured values.The consistency correlation coefficients(CCC)of the 3D mapping based on the spline function were 0.72 and 0.75,which were higher than the other functions in the same form of 3D mapping(CCC were between 0.64 and 0.74).For the horizontal mapping methods,the accuracy of the ordinary kriging was better than that of the random forest,the CCC of the former was between 0.67 and 0.75,the latter was between 0.64 and 0.72;(3)The two mapping forms of the two-step model had little influence on accuracy.Only in the case of prediction for bottom layer,form A i.e.,horizontally mapping simulated walues of a depth function was better than form B(i.e.,simu

关 键 词：三维制图 土壤有机碳 深度函数 两步模式 

分 类 号：K903[历史地理—人文地理学]