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利用遥感判读和地面样地结合，进行各类土地面积和森林蓄积调查，是森林资源清查常用的方法。在遥感资料（卫片，航片或磁带）抽取部分或全部样点作为第一相样本，再抽取部分地面样地作为第二相样本。第一相样本只进行地类判读，第二相样本同时进行地类判读、类实测和蓄积量测三项工作。这个方法称为面积蓄积同时两相抽样。洛兹等的森林抽样技术一书中分别讲述了面积的两相抽样和蓄积的两相抽样，但没讲述二者如何结合使用，也没有讲述判读地类数与地面地类数不相同时如何处理。该书还有些地方没写太清楚。笔者最近重新考查了书上的公式，得到了一些比它更好的结果。此外我们给出了调整后地类面级误差的联合分布。这些结果可以很好地用于面积蓄积同时两相抽样。本文介绍面积蓄积同时两相抽样的基本原理和统计计算步骤，有关公式的严格证明将另文发表。本文一至四节是面积蓄积同时两相抽样的基本公式，第五节说明计算步骤，最后讨论几个问题。需要说明的是，本文的方差公式都是极限分布公式，未作有限修正（洛兹书上给出的也是极限分布公式）。
The use of remote sensing interpretations and the combination of ground samples for various types of land area and forest inventory survey is a common method of forest inventory. In the remote sensing data (satellite films, aerial photos or tapes) to take part or all of the sample as the first phase samples, and then extract part of the ground sample as the second phase sample. The first phase of the sample only to class interpretation, the second phase of the sample at the same time interpretation of the ground class measurement and accumulation of three measurements. This method is called area accumulation while two-phase sampling. Lords et al. Describe the two-phase sampling of the area and the two-phase sampling of the accumulation, respectively, but do not describe how the two are used in combination, nor do they describe how the type of interpretation differs from that of ground types deal with. The book still did not write too clearly in some places. I recently re-examined the book’s formula, got some better results than it. In addition, we give the joint distribution of the adjusted ground-level errors. These results can be well used for area accumulation while two-phase sampling. This article introduces the basic principle and statistical calculation steps of area accumulation and two-phase sampling. The strict certification of the formula will be published separately. The first four sections of this article are the basic formulas of area accumulation and two-phase sampling. The fifth section explains the calculation steps and finally discusses several issues. It should be noted that the variance formula in this paper is the limit distribution formula, without any limited modification (given in the book of Lotz is the limit distribution formula).