Potential for crown diameter as a predictor of canopy cover under National Park conditions
The global loss of biodiversity has led to relentless calls from conservationists to protect the environment and natural habitats. The objective of this study was to determine the effectiveness of crown diameter for prediction of canopy cover under national park conditions. The study was conducted in Etosha National Park, Namibia in 2015. Three tree species, namely Combretum imberbe, Colophospermum mopane and Terminalia prunioides were considered as representative members of the park species based on their relative population density. The study employed regression analysis to examine the nature of relationships between tree crown diameter (the dependent variable) and tree height, diameter at breast height (DBH) and distance from watering holes as independent variables. The regression coefficients for Combretum imberbe were not significant (P = 0.116; P = 0.431; P = 0.884, respectively), suggesting that crown diameter was not well estimated by these explanatory variables. On the other hand, there were significant relationships between DBH and crown diameter, as well as between crown diameter and tree height. Tree height emerged as the stronger predictor of crown diameter for both Terminalia prunioides and Colophospermum mopane. Therefore, the relationship between tree height and crown diameter as explained by cubic function can further be used to evaluate and estimate canopy cover under national park conditions.