基于样点的数字土壤属性制图方法及样点设计综述

Sample-based Digital Soil Mapping Methods and Related Sampling Schemes

土壤剖面数据与土壤类型图按照某种原则进行连接是目前获取土壤属性空间分布信息的主要方法,这种传统的土壤属性制图方法以土壤专家的"经验"和手工描绘为基础,耗费资本高、生产周期长。数字土壤制图通过借鉴先进的空间信息处理技术和高分辨率地形数据的优势,能够快速地获取高精度、高分辨率的土壤属性空间变化信息,是一种精细、高效、经济的土壤属性制图技术。本文详细介绍了基于样点进行数字土壤属性制图的3种方法:①基于空间自相关的方法;②基于空间自相关和土壤-环境关系混合相关的方法;③基于土壤-环境关系的方法。同时,为保证样点能够全面地捕捉到研究区内土壤属性空间变异特征,以上3种方法都对样点的数量、分布或典型性提出了较为严格的要求,即样点应具有全局代表性。因此,如何设计样点成为数字土壤属性制图中的一个重要问题。依据样点设计过程中是否能够整合已有样点,本文将样点设计方案分为采样设计方案和补样设计方案两种,并对其分别进行了详细的综述。

Traditional soil mapping methods, relating soil survey profiles with soil type maps under some criterions, based on soil surveyors＇ experience and manual delineation process are time-consuming and cost-prohibitive. The digital soil mapping （DSM）, which takes advantage of the advancement in spatial information processing techniques and the increasing availability of high resolution spatial data, is feasible in providing soil distribution information at the required level of accuracy and spatial details. Field samples are the most important data sources for DSM. There are three DSM methods based on samples which are the ones based on spatial autocorrdation, the ones based on relationship between soil properties and environment co-varieties as well as the hybrid ones based on both spatial auto-correlation and the relationship between soil properties and environment co-variates. In order to capture the global representativeness of samples for characterizing the spatial variation of soil property, these kinds of methods all have serious requirement for the size, distribution and typicality of field samples. So, sampling design is an important process for DSM. Schemes for sampling design can be grouped into two categories based on whether the existing samples can be integrated in the sampling process： simple sampling scheme and integrative sampling scheme. This paper provides an overall review over these aspects of digital soil mapping.