多期森林连续清查的研究

<正> 森林连续清查在我国已普遍展开,有的地方已进行第三期甚至第四期清查。进入多期后,如何充分利用每期调查的信息对森林现状及变化进行最有效的估计已是十分迫切的现实问题。 60年代末美国Cunia等人最早把方差最小的无偏线性估计方法从两期引伸到多元三期和更多期。本文在其基础上作了以下工作:(1)讨论了几种可供实行的三期清查方案并导出了估计公式,为应用和分析方便还导出了其简化形式;(2)对估计值的方差在理论上作了效率分析并与两期清查作了比较;(3)以吉林省三岔子林业局南部地区的三期连续清查为例具体说明和比较了这几种方案的实际应用。

A STUDY OF CONTINUOUS FOREST INVENTORY ON MORE THAN TWO OCCASIONS

In this paper five alternative plans of SPR (Sampling with Partial Replacement) on three occasions are described and discussed. Simplified formulae of the estimates and their variances have been derived. Estimated efficiency of these plans has been’ analysed. An illustration of the application of the forest inventory on three occasions is given and comparisons between the five sampling plans have been made in accordance with their actual practice.