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.La perte mondiale de biodiversit\ue9 fait partie des causes des appels incessants des \ue9cologistes pour prot\ue9ger l\u2019environnement et les habitats naturels. L\u2019objectif de cette \ue9tude \ue9tait de d\ue9terminer l\u2019efficacit\ue9 du diam\ue8tre du houppier pour pr\ue9dire la couverture de cime dans les conditions des parcs nationaux. L\u2019\ue9tude a \ue9t\ue9 faite dans le parc national d\u2019Etosha, en Namibie en 2015. Trois esp\ue8ces d\u2019arbres, \ue0 savoir Combretum imberbe , Colophospermum mopane et Terminalia prunioides ont \ue9t\ue9 consid\ue9r\ue9es comme des membres repr\ue9sentatifs des esp\ue8ces du parc en fonction de leur densit\ue9 de population relative. L\u2019\ue9tude a utilis\ue9 une analyse de r\ue9gression pour examiner la nature des relations entre le diam\ue8tre du houppier (la variable d\ue9pendante) et la hauteur de l\u2019arbre, le diam\ue8tre \ue0 hauteur de poitrine (DBH) et la distance des trous d\u2019arrosage (variables ind\ue9pendantes). Les coefficients de r\ue9gression pour Combretum imberbe n\u2019\ue9taient pas significatifs (P = 0,116; P = 0,431; P = 0,884, respectivement), ce qui sugg\ue8re que le diam\ue8tre de la couronne n\u2019\ue9tait pas bien estim\ue9 par ces variables explicatives. D\u2019un autre c\uf4t\ue9, il y avait des relations significatives entre le DBH et le diam\ue8tre de la cime, ainsi qu\u2019entre le diam\ue8tre de la cime et la hauteur de l\u2019arbre. La hauteur des arbres est apparue comme le meilleur pr\ue9dicteur du diam\ue8tre du houppier pour Terminalia prunioides et Colophospermum mopane. Par cons\ue9quent, la relation entre la hauteur des arbres et le diam\ue8tre du houppier, comme expliqu\ue9 par la fonction cubique, peut en outre \ueatre utilis\ue9e pour \ue9valuer et estimer le couverture de cime dans les conditions du parc national

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Not AvailableBiomass, carbon storage and carbon dioxide mitigation potential of plantations of Populus deltoides, Eucalyptus tereticornis, Dalbergia sissoo, Mangifera indica, Litchi chinensis and Prunus salicina were assessed. Being economically viable, such tree plantations are grown by farmers on a large scale in north India. The maximum total biomass (94.8Mgha-1) was observed in a 10-year-old D. sissoo monoculture plantation, followed by an 8-year-old P. deltoides block plantation (63.0Mg ha-1). Carbon stocks ranged from 4.51Mgha-1in an 8-year-old P. deltoides boundary plantation to 43.39Mgha-1in D. sissoo plantation. The carbon sequestration rate for P. deltoides block and boundary plantations was estimated to be 2.75 and 0.43MgCha-1year-1, respectively. Eucalyptus boundary plantation sequestered 0.84MgCha-1year-1while D. sissoo plantation sequestered 2.73MgCha-1year-1. Among fruit trees, the highest sequestration rate was recorded in M. indica (mango) plantation, with 1.43MgCha-1year-1.Not Availabl