九州大学学術情報リポジトリ Kyushu University Institutional Repository FOREST INVENTORY BY SAMPLING METHODS. 1953 Kinashi, Kenkichi https://doi.org/10.15017/14955 出版情報：九州大学農学部演習林報告. 23, pp.1-153, 1954-03-30. Research Institution of University Forests, Faculty of Agriculture, Kyushu University バージョン： 権利関係： PART 1. INTRODUCTION CHAPTER 1. GENERAL DESCRIPTION 1. A motive for studying this subject. Forestry is concerned not only with the individual tree, but also with groups of trees, such as stands or forests. Especially, in the sciences of forest manege ment and forest mensuration, this study is needed. Since olden times, many statistical studies for forestry and forest mensuration have been made by many famous people, but these methods have been brought to a deadlock. The sample-plot method as hitherto used has the defect of being inadequate for precision measurement. With the recent development of sampling methods, it has come to be demanded of timber surveyors as of workers in other fields of statistical research that they have a clear conception of sampling errors. In Japan, we have not been able to study the science of modern statistics applied to forestry. There are 3 important reasons for this, I think. The first of them was the imitation of German forestry, the second was that insufficent attention was paid to the importance of forest mensuration and the third was the organization of our state and our educational system of forestry. Many students and graduates from universities majoring in forestry have many unsolved questions about forest mensuration in their fields of research and practice. Moreover, they did not have the methodical foundation of modern statistics. But there were useful works and laborious achivements made in the past, and detailed inventories were made in many countries. In the National Forest Service, complete maps and timber volume lists over the whole subcompartments are prepared. And even in the private forests, there are concise maps and timber volume lists. However, we cannot gauge their pre cision and reliability. This defect is a vital problem. Because the old method. is very expensive and inefficient, it should be discontinued. Then there is the necessity for the reconstruction of forest mensuration in Japan. And it must begin as soon as possible, because it is clear that the practice and science of forestry can not expect further developments without information based upon the recent progressive statistics. 2. The science of modern statistics applied to forestry. There are many problems of statistics involved in practice and scientific reseach. First, forest mensuration is a problem in biological statistics, and it is the foundation of forestry. Forest management, silviculture and forest ecology need the technique of sampling methods and experimental designs. And, also the other sciences of forestry are situated in the same relationship. These problems must be solved in accordance with the given cost and the resercher's ability. 3. The objects of this study. There are two main objectives in making this study. The first objective is to apply the practical forestry inventories by sampling methods supported by the Japanese Forest Service. The second objective is the modern statistical reconstruction of forest mensuration in Japan. Japanese forests have many charactristics, i.e. the patch of stand, the steep slope, the artificial plantation, etc. So line-plot methods or strip survey can not be used in Japan. Usually we have used the sample-area method. It is clear that these jugement sample plots are dangerous. Also these jugement plots never supply any information as to the aggregate. Our forest mensura tion was based on the foundation of the jugement sampling method. If ran dom sampling methods are used, our old forest mensuration method should be reconstructed on the foundation of modern statistics. This is the second objective. But it is a very large and difficult problem and is impossible to solve without the cooperation of many research workers. CHAPTER 2. RECENT DEVELOPMENTS OF SAMPLING SURVEYS IN FORESTRY. 4. Recent developments in sampling surveys in American forestry (16)(17)(20) First it is very useful to learn of the progressive traces of sampling surveys in !American forestry. They are coveniently devided into four stages of age. In each of these stages we can find many informative reports as follows ; (1) The first stage ; By W. G. WRIGHT (1925), R. H. CANDY and W. M. ROBERTSON (1927) the number of plots needed for constant accuracy was calculated by the standard error formula. It is elementary work but it is the primary basic foundation of the recent development of sampling designs. Their methods of caluculation of the number of plots are shown as follows. If the standard deviation is noted by s and the standard error is noted by S , We can accept the line-plot method as a more precise and reasonable method than the strip method. The line-plot method is easily applied by a systimatic sampling procedure. This is the foundation of the most recent sampling method in forestry. (2) The second stage ; Since the McSwenyMcNary act was passed, there has been much done in reseach for the area by forest types, timber volumes and growth-rates (1928). SCHUMACHERand BULL (1932) worked out a line-plot survey in the forest of Salix and Populus on the Mississippi delta zone. 10 parallel lines apart 3 miles from each other running across the river from east to west, and 1918 1/4-acre plots spaced 10 chains on the lines are measured over 503,000 acres, with 0.1 per cent of total area. There are many similarities between the plot count method and the line measurement data. But both data are treated by numeri cal formula. The percentages of forest types determined by both methods are almost identical. Units of 1/2 mile are best to estimate the mean. The total volume is calculated by the formula ; This study is very informative for plotsampling and can be applied to Japanese regions consisting of many patched forests. GOODSPEED'S(1943) im proved line-plot method has the 1/8-acre plots spaced 165 feet from each other on parallel lines 330 feet apart. This method can be worked by one man. The same result was obtained by the strip method with a 33' width. Also in the volume, the difference be tween these two methods is not significant by the F-test. The strip method is more expensive than the plot method. J. F. PRESTON (1934) described how to do the combination between the forest mensuration and the modern statistics in the illustration of the cruising to pulp wood. His cruising methods cannot be accepted as perfect but in our country even this level of perfection has not been reached yet. MUDGETT and GEVORKIANTZ (1934), in order to verify the precision of estimate, analyzed mathematically their survey data according to the distributions of Bernoullian, Poisson and Lexis Series. And they claimed that the distribution of the forest types were not due to the Bernouelian distribution illustrated by SCHUMACHERand BULL, but due to the Poisson distribution. For surveys made of large areas of forest, if the Poisson condition can be used, there are sufficient budgets for reseach. If the budget is insufficient, the Lexian condition should be used. (3) The third stage ; A. A. HASEL (1938) tried the analysis of variation of the Black mountain forest. This report was very interesting to us, and gave us our motive to start research in the Shiragadake forest. The total area was divided into nine sections each one mile square. A section was divided into four quarters, a quarter into four forties, a forty into four tens, a ten into two fives, and a five into two basic plots. A basic plot is 2.5 acres, that is about 1 ha. The timber volume on the basic plot was distributed normally. SNEDECOR'S F-test was tried on these variance ratios. Then he recognized that these volumes changed heterogeneously from place to place. His F-tests were sig nificantly different in all cases. The narrow shaped plot with the longer side set at right angles to the contour line is more effective. The variance of the mean is given in the fol lowing formula ; There are many small area stands having irreguler boundaries in Japan, therefore the shape of the blocks will not be constant unless the boundary of the adjoining subcompartrnent is removed. If we work out the large scale inventory without restriction of boundaries, we could use this method. But our inventory system consists of the summation of many subcompartments with detailed lists of individual stands. There are many problems in conec tion with sampling designs. HASEL (1941) studied the variance of the volume of standing timber in the pine region of California. For the purpose of an estimate of variance two plots were taken at random within each block and the following formula applied ; where s2 is the variance of volume per plot, x1 and x2 are the volumes of the two plots cruised in a block, and n is the number of plots cruised. The size of block is constant, being 20 acres, with dimensions 10 by 20 chains. It is about 8 hectare (200 m x 400 m). Plot length is always taken parallel to the long side of the block, the single plot per block is taken in the center. Plot size varies from 1 by 2 chains in a 1 % cruise to 1 by 20 chains in a 10 % cruise. Sampling error will vary according to the values shown. The degree of vari ance will depend upon the size of the tree and the distribution of stems on the ground.