Models for estimating crown projection area from stump diameter for Tectona grandis Linn. f. in the tropical rainforests of Nigeria

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The estimation of growth variables for a cleared tree is crucial in forest management. Most importantly, growth variable estimation for cleared trees allows for the conviction of illegal loggers in judicial proceedings and biomass estimation. Hence, the present study developed empirical models that are capable of precisely estimating the crown projection area (CPA) of trees from tree’s stump diameter (Ds) to serve as a crucial tool for evaluating tree loss and as descriptive evidence to inform the litigation process. The data for this study were gathered from 36 randomly laid 25 m×25 m temporal sample plots within six stand ages of Tectona grandis within a Nigerian reserved tropical rainforest. Least squares method was used to fit six regression models, namely simple linear, power, single logarithmic, growth, reciprocal, and square functions. The power model estimated CPA from Ds most appropriately by employing the lowest values of the root mean square error (8.42 m^2), Akaike information criterion (6514.13), and Bayesian information criterion (6524.79). Furthermore, t-test result yielded a non-significant (p=0.431) difference between the observed and predicted CPA utilizing the power model. Hence, the power model was recommended for the conversion of counted stumps into harvested trees’ CPAs.

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Regression models , stump , timber trespass , tree crown , tropical rainforest

Forestist

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Forestist