Tropical forest dynamic after logging: natural regeneration and growth of commercial tree species in the south-east Cameroon

Summary

The objective of this PhD thesis is to compile silvicultural information fundamental to the sustainable management of tropical lowland rain forests in Cameroon. In many cases the sustainable utilisation of tropical rain forests is not possible because of the prevailing economic and social circumstances. Often, however, it is simply a matter of the lack of basic technical information. For example, in most of the regions where the sustainable management of tropical rain forests is envisaged, there are no reliable data concerning the growth of the main commercial species. The planned harvesting cycles are based solely on rough estimates. One reason for this are the problems associated with the supervision of long term research sites, and another is that in many parts of the Tropics it is not possible to carry out annual ring analysis instead of repeated increment measurements. In this study, investigations are carried out on commercial deciduous species with clear annual rings, namely: Entandrophragma cylindricum, Entandrophragma utile, Entandrophragma candollei, Erytrophleum ivorense and Milicia excelsa. Tree ring investigations are based on the stumps of felled trees and increment cores. The success of regeneration of the main commercial species in the exploited forests will also be examined. The regeneration investigations are concentrated on the areas surrounding gaps created as a result of harvesting. These occupy only a very small proportion of the area, as on average only one tree is extracted every 2 ha.

The Republic of Cameroon possesses over 23.9 million hectares of tropical natural forests (FAO, 2000). The evergreen moist forests (5.3 million hectares) and the semi-evergreen moist forests (12.2 million hectares) make up an important component of the moist forests area of the Congo Basin (ONADEF, 1999). These moist forests are situated to the south of the country and have for a number of decades been the basis of a strong timber industry. South east Cameroon, the region in which the studies will take place, is the centre of forest utilisation in Cameroon.