V. J. Chacko

Abstract

The need for a statistical appraisal of the present methods in selection and processing of sample plots data and in particular of assessing statistically the precision of the common mensurational methods in forestry is pointed out. Simple methods of studying the shape of cross sections of stems are suggested. Techniques for estimating the bias. and precision in the common procedures of callipered diameters in estimating the sectional area are given and indicative results obtained for four timber species.

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V. J. Chacko

Abstract

The design of a statistical sampling scheme includes decisions on the following questions: - (i) The type and size of the basic sampling units. (ii) Number of sampling units or in other words the intensity of sampling. (iii) The distribution of the units over the forest area. (iv) Method of analysis of the data. The answers to these questions require both statistical theory and experience data in the form of considerable amount of experimental sampling. The basic investigations and data needed for designing appropriate sampling procedures in forest surveys are discussed. Lack of adequate experience data relating to the forests in India is pointed out. The available data is reviewed. Based on an analysis of Mount Stuart data, the relative efficiency of different plot sizes are studied. The serial correlations were computed and the theoretical aspects of the inter-relationship between the topographic variation and the design of survey. Discussed. The necessity for conducting pilot surveys to obtain information on the pattern of variability, the efficiency of methods of measurement and operational cost is stressed.

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K. P. Sagreiya , V. J. Chacko

Abstract

Section I deals with the mathematical analysis of Brandis idea of yield regulation on the lines initiated by Sagreiya and based on the data used by him, by Mishra, and Tiwari. The interesting conclusion obtained was that in the third and subsequent cycles, exploitation can be on the basis of equiextensive coupes. Section II presents a working formula which is safe and simple to use in practice and consistent with the concept of Brandis. Some remarks are also given on the basic assumptions used in Section I. Readers interested only in the general argument and final results may omit Section I which is mainly of theoretical interest.

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K. P. Sagreiya , V. J. Chacko

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Site quality index for even aged teak forests based on 'top height' is defined and a convenient method of determining the site quality explained. Three equations giving (1) the top height corresponding to a site quality and age, (2) the normal diameter corresponding to a top height and (3) the normal number of trees per acre given the average diameter are presented. These three equations essentially summarise the yield table for even-aged teak forests. Based on the equations the yield tables for different quality classes are reconstructed. A general method of predicting the average diameter at any age of a specified number of initially selected elites uniformly spaced and tended is presented and tables and graph given for Quality Class II forests. The application of the graph to the problem of making optimum use of growing space in growing poles of a specified diameter is explained.

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V. J. Chacko

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This paper deals with some of the feasible sampling methods for the survey of bamboos, canes and reeds. In general two methods appear to be promising. In either case the first step consists in stock mapping the forest area and selecting a stratified sample of units for field enumeration. The actual field enumeration in the case of bamboos may be (1) using line plots of suitable size depending on the density of the area and enumerating all culms within the plots with subsidiary observations in a sub-sample on clump size for management purposes or (2) in low density areas or if the units are small by complete enumeration of clumps and enumeration of culms from 2 randomly selected clumps from sets of 40 clumps. The promising method for the survey of canes and reeds is a low intensity line plot sampling.

An outline of the scheme of pilot surveys proposed for bamboos, reeds and canes is
given and the cooperation of the States requested.

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V. J. Chacko , A. S. Rawat , G. S. Negi

Abstract

The results of point sampling conducted, probably for the first time in India, in 45.32 hectare chir stand of Champion Block, New Forest, using wedge prisms of basal area factors 10, 15, 20 and 25 in British units (2.296, 3.444, 4.591 and 5.739 in Metric units) are presented and compared with plot sampling of the same area. The study has demonstrated that prisms with B.A.F. 10 or 15 are most suitable for enumerating the stand. The results also indicate that point sampling based on 20 to 25 objectively selected sample points in 30 to 40 year old chir stands could furnish estimates of basal area per hectare and number of stem. per hectare with standard errors of 5 and 6 per cent of the true values Respectively.

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V. J. Chacko

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V. J. Chacko , H. K. Mukerji , S. N. Mitra

Abstract

The paper gives the results of a study on the precision of the estimate of mean from sub sampling of strips obtained as a stratified random sample of plots within strips as compared to Random line plot and Partially systematic sampling. It has been found from the analysis of a complete enumeration data of Mount Stuart, Madras and a 20 % systematic strip enumeration data of 'sal' from Uttar Pradesh, that stratified random sampling within strips gives more precise results than that of Random line plot sampling for any intensity of samping but less precise than that of Partially systematic sampling when the intensity of sampling within strips is lower than 1 in 6.

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V. J. Chacko , A. S. Rawat , P. C. Dave , S. Singh

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This paper presents the results of the pilot survey conducted in Bori, Hoshangabad Forest Division, M.P., the second in the series of pilot surveys for bamboos conducted by the Statistical Branch, F.R.I. The terrain was quite hilly and undulating but the area was among the best bamboo producing areas of the Division. The results of the pilot survey have demonstrated that separate estimates for each compartment with a margin of error within 5% , could be obtained if a complete count of clumps is made and 1 %, clumps selected randomly are used for counting culms according to various age and end use classifications. The pilot survey has also demonstrated the usefulness of sub-sampling of sub-compartments when estimates are desired only for large areas comprising of a number of compartments.

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V. J. Chacko

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Some basic aspects to be considered for designing and analysing forestry spacing and/or thinning experiments are indicated and an appropriate class of systematic design proposed for such experiments. Useful values of the parameters of the designs are obtained. The relevant models for representing the relationship between the yield and spacing or density per unit area of trees useful in the analysis of the data are presented.

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V. J. Chacko

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The theory and the utility of sequential sampling with special reference to surveys of insect pests or diseases in forests are presented. The method is recommended for quick routine surveys in ascertaining the current status of pests or diseases in forest areas and also as a guide to decide, at the time of outbreaks of an epidemic, whether or not control measures are to be undertaken.

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V. J. Chacko

Abstract

It is suggested that the progress in the application of statistical methods in forestry and forest products work, in any country, can be divided into three stages; the primitive stage, the proliferation stage and the scientific stage. It appears that we have reached the middle of the second stage of development which is characterized by fairly wide appreciation and use of elementary statistical techniques in forest work. Typical instances of the possible misuse of statistics occasioned by mechanical use of the methods are mentioned in the hope that it will lead to correct application of the statistical techniques.

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V. J. Chacko

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In this paper, the basic components, operation and potentialities of a digital computer are outlined and the major effect on forestry development indicated. The better computational facilities provided by an electronic computer can stimulate developments which can have a revolutionary impact on Indian Forestry. The computer can lead to greatly increased all round competence in tbe application of known methods, both in speed and in comprehensivences.It can increase the output of the departments and give a new dimension to the research efforts. It can also be utilized to evolve new techniques and for improving current methods and practices. However, the computer, naturally, imposea also certain obligations on the forest workers.

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