Effects of slenderness coefficient in crown area prediction for Tectona grandis Linn. f. in Omo Forest Reserve, Nigeria

J. U. Ezenwenyi, Onyekachi Chukwu

Abstract


Crown area which is crown size, is closely related to the photosynthetic capacity of tree and it is an important parameter to characterize biomass, leaf area and wildlife habitats. Conversely, assessment of crown dimensions still remain one of the most difficult and tedious task in forestry. The difficult measurements and the sensitivity of crown dimension on management makes it desirable to develop estimation procedures based on variables that are easier to measure than crown extension itself. The main objective of this study was to develop and observe the effects of tree slenderness coefficient in predicting crown area for Tectona grandis in Omo Forest Reserve. Twenty temporary sample plots of size 20 m x 20 m were randomly selected across the stand ages (9, 11, 12 and 18 years). Tree growth variables measured from each plot include diameter at breast height (Dbh) ≥ 5 cm, total height (THt) and crown diameter (CD). The data was analysed using descriptive, correlation and regression analyses. Amidst the models developed and verified, double logarithmic function with adj. R2 = 62.0%, RMSE = 0.265% and PRESS = 0.263 gave the best fit and predictive ability. This was also supported by the undeviating bands of the graphical analyses of the residual. Conversely, the inclusion of TSC had impact on the predictive abilities of the models which implies that slenderness coefficient typically indicates the size of crown dimension, centre of gravity and a better developed root system. Therefore, it is recommended that the model can be used by forest managers for the development of stocking guideline.

Keywords


Crown area; Dbh; Tectona grandis; Model; Tree slenderness coefficient

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References


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