Definition of the System Yield Table

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A project study on the development of new type of yield table has been carried out since 1989. The result of this study was reported as "System Yield Table" in 1992 and "Programs of System Yield Table" in 1995. This report discusses the question "What is the system yield table ?" by overviewing programs developed. The yield table of the type used widely for Japanese forest management and forest planning to date since the 19th century is called a "conventional yield table". The conventional normal yield table or empirical yield table shows the estimated values of forest stand growth, in case of specific tree species in a specific area and under specific management as variables of site, stand age and density. This is called the yield table of the first generation. A growth diagram of the stand prepared with the density effect of the stand as a basis is called a "forest stand density-control diagram". This diagram shows relationship corresponding to stand density, volume, tree height and diameter in the growth process of the stand on the plane. This can estimate the yield in the case of various density-controls. The conventional yield table of the first generation was line information on growth, while this density-control diagram would be plane information on growth, and is called the "yield table of the second generation". The basic characteristic of the system yield table is that it is a computer-program with an algorithm to estimate the growth process in the future in cases of various types of management for the forest stand under various conditions. The system yield table can express countless growth processes in countless stands in a multi-dimensional space formed by variables including tree diameter, height, volume, density, tree age, thus it is called the third generation yield table to indicate the whole space. Evaluation shall be made for the function level of the system yield table by explaining the condition of the forest stand, management method and growth process. Functions are explained by the following four items. (1) Quantity and quality of information on estimating forest stand condition, management and growth (information quantity). (2) Range of applicable forest stand (applicable range). (3) Usability of system yield table program (easiness of use). (4) Rationality of growth model used for estimation (logic).
森林計画学会の論文
1995-10-00

Definition of the System Yield Table

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