The relation of number of trees and their average diameter in pure, full stocked and even-aged stands
1956 Volume 38 Issue 4 Pages 130-135
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1956 Volume 38 Issue 4 Pages 130-135
The significant correlation existing between number of trees per unit area and their average diameter is shown so clearly throughout the life of a single even-aged stand as to leave no room for doubt as to its existence. There are already several equations that express the relationship; however, they are not always adequate or simple. This paper presents a new equation that everyone will find easy to understand and compute. The average area ocupied by trees in a pure, full stocked and even-aged stand is obtained by dividing the area by the number of trees, and by conversion it may be used to give the approximate average mutual distance of trees. This is expressed by the equation,
C=(A/N)1/2 in which C is the everage distance of the trees from one another. A isthe area of the stands, and N is the number of trees. The correlation existing between C and the average diamerter is computed according to the regression equation,
C=a+bD
in which, a and b are constant, and D is the average diameter at breast high. It is then transformed into a new equation which representsthe relation existing between the number of trees and their average diameter,
_??_in which, if A is unit area, A would seem to be a constant one.
In this work, the fitness of the regression equation was tested on the temporary sample plots for constructing 15 local normal yield tables for pure and even-aged stands, and others. They comprise Akamatsu (Pines densiflora), Sugi (Cryptomeria japonica) Hinoki (Chamaecyparis obtuse) and Karamatsu (Larix kaempheri) of the most important reforestational species in this country. The results are represented in Figure _??_-6 and Table 1_??_3. The fitness of the data to calculated equations was generally very good. However, in most plantations, because it deviated from the data up to the ground covered by their crown, it would seem to express the relation existing between C and D. B. H of the stands where a fierce life struggle for existence is present.
