Silviculture in African moist forests : do we have new answers to old questions?

The silviculture of African tropical moist forests has a long history punctuated with (few) successes and (many) failures. The European foresters in charge of managing forests in the African colonies realized early - e.g. 1900 in Nigeria - that they were facing a complex ecosystem with a low volume per ha of commercial timber. Somewhat a different situation than the one faced by foresters in South-East Asia where forests were rich in commercial timber of the Dipterocarpaceae family. Confronted to a highly dispersed, highly valuable timber resource and entrenched in their temperate forester culture they worked on ways to produce ?the greatest timber volume, as homogenous as possible?. Two main schools of thought confronted one another, promoting respectively natural regeneration vs artificial regeneration techniques. In the 1970's, realizing the many difficulties and costs linked to enrichment planting, French foresters decided to focus on silvicultural operations targeted at future crop trees, rather than trying to actively favor regeneration. But they came quickly to consider that logging will in most cases be the only economically feasible silvicultural operation in the course of a felling cycle. Attention shifted to establishing simple logging rules supposedly ensuring long-term timber production. Today, we face what foresters in the 30's and 40's had anticipated: the "picking" of a small number of valuable light demanding trees through highly selective logging is slowly but surely exhausting these populations as canopy is not opened enough to allow regeneration. In countries where industrial logging started early, several important commercial species like Assamela - Pericopsis elata - and most species of Entandrophragma are becoming rare and some logging companies are beginning to turn to silviculture, thus demonstrating the modernity of old questions and the urgency of finding answers. We went back over 64 years of publications on silvicultural trials in the journal Bois et Forêts des Tropiques to highlight the conditions of success, and to propose ways forward. (Résumé d'auteur