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本文提供了从亚地中海地区放牧地上取得的横向变化(区别于随时间变化的纵向变化,译者注)的土壤流失数据.改进过的Gerlach水槽用来测量细沟侵蚀和细沟间侵蚀.为了找到精度较高的估算土壤侵蚀的概率抽样方法,对不同数量和不同宽度的小区试用了随机抽样、系统抽样、分层随机抽样以及成串抽样四种抽样技术.如果分细沟和细沟间两个次总体进行抽样,“随机”和“分层随机”法给出几乎相同的标准误差;成串抽样产生的误差较大,该法基本无效;系统抽样法,虽然可以选择大小比较经济合算,有更高精度的样本,但其可靠性很大程度上依赖于试验地上细沟的数量.如果只对细沟间侵蚀次总体抽样,而对细沟侵蚀量实测,可取得最小的标准误差.这样,上述四种抽样法都获得相同的精度.
This article provides data on the amount of soil erosion from the lateral variation of the grazing land in the Mediterranean region (as opposed to the longitudinal change over time). The modified Gerlach sink measures rill erosion and erosion between the gullys Find the probability sampling method of estimating soil erosion with high precision, and try out four kinds of sampling techniques, random sampling, systematic sampling, stratified random sampling and string sampling for different numbers and different widths of the plot.If there are four sampling techniques Sampling is performed twice in general, and the “stochastic” and “stratified random” methods give almost the same standard error; the error caused by the string sampling is relatively large, and the method is basically ineffective. Although the sampling method of the system is economically viable , But with higher precision samples, but its dependability depends largely on the number of fine gutters on the ground. If only the total number of erosive subsamples is sampled and the rill erosion is measured, the smallest standard error can be obtained In this way, the above four sampling methods all obtain the same precision.