Les brousses secondaires en Afrique Equatoriale

Abstract

“Secondary” forests are very different to “primary”, “noble” forests with their tall trees. Their exuberant, inextricable vegetation, with more lianas and small shrubs than trees, grows on formerly forested lands cleared for agriculture. In inhabited regions, they generally sur- round villages and grow along roadsides, pushing the primary forest back to rocky hillsides and swamps. In Equatorial Af- rica, “secondary” forests account today for 50 to 75% of all forested areas. These forests form in three stages: (i) seedlings appear of fast-growing sun-loving species ( Musanga sp., Vernonia sp., Anthocleista sp.), which are not the same as primary forest species and which disperse their seeds over long distances; (ii) formation of an understorey, made up of the same shrub species as in “primary” forests but mixed in this case with a second group of banal sun-loving species characteristic of “secondary” forests, which quickly grow as high as the first group and sometimes higher; (iii) gradual reconstitution of “pri- mary” forest with abundant Sapotaceae, Guttiferae and hard-wooded legu-minous species that are capable of regenerating in the undergrowth and through which some very tall trees eventually grow through the canopy. Okoume ( Aucoumea klaineana ), a valuable species typical of “secondary” forests, is common in the so- called “primary” forests of Gabon, which in fact are on formerly cleared forest land. Today, the high potential of these “sec- ondary” forests must not be allowed to “go up in smoke”. Quite the reverse: we must learn to guide their development to hasten the establishment of commercially valuable species. Abstract adapted by the editorial team.