Effect of silvicultural treatment on growth and mortality of rainforest in Surinam over long periods

Results of silvicultural experiments in Surinam, carried out since 1965, have shown that volume increment of marketable timber species can be effectively stimulated by treatments such as liberation and refinement. Such refinement might, for example, initially reduce the basal area of non-marketable species from ca. 20 to 6 m(2)/ha and the total basal area to some 10 m(2)/ha. The effects of these treatments, however, generally last for limited periods of <10 years. Even in a forest management set-up with relatively short felling cycles of 20-30 years, treatment has to be repeated to be fully effective. In three experiments, including a large-scale field trial, the treatment stimulated increment and recruitment but both slowed down markedly with time. Mortality is variable, but has a tendency to increase with stronger interferences. The large-scale field trial, which had received a single initial treatment, has grown enough volume for a second harvest of 20-30 m(3)/ha after 20 years. Increment and final stand structure would have been much improved with three treatments during the cycle as originally planned. (C) 1999 Elsevier Science B.V. All rights reserved.