Infodoc : Sciences, Techniques et Culture

For sustainable management of tropical rainforests an operable silvicultural system is a must to keep the forest productive. Such a system need to be locally adapted. In this context the CELOS Management System developed since 1975 in Suriname promises to be a successful and ecological sound silvicultural system adapted to mesophytic forests of the Guyanas.The presented study investigates the development of forest stands of a CELOS experiment 14 years after a harvest and compares three différent treatment intensities on one exploitation level, and examines, if a single refinement is sufficient to allow a second harvest in a cycle of 25 years. For this purpose mortality, ingrowth, diameter distribution, basal area, bole volume and quality of trees of a harvestable size have been asse[...]

For sustainable management of tropical rainforests an operable silvicultural system is a must to keep the forest productive. Such a system need to be locally adapted. In this context the CELOS Management System developed since 1975 in Suriname promises to be a successful and ecological sound silvicultural system adapted to mesophytic forests of the Guyanas.The presented study investigates the development of forest stands of a CELOS experiment 14 years after a harvest and compares three différent treatment intensities on one exploitation level, and examines, if a single refinement is sufficient to allow a second harvest in a cycle of 25 years. For this purpose mortality, ingrowth, diameter distribution, basal area, bole volume and quality of trees of a harvestable size have been assessed for all trees of commercial and non commercial species with an diameter above 15 cm at reference height in three différent research plots of 1 ha each (no refinement, one
single light refinement and one single heavy refinement, same harvest level of about 15 m3/ha in all three plots). These date recorded in 1997 were compared to available data recorded in 1983. Although instead of two originally planned treatments only one refinement had been carried out, the increment of volume of trees of marketable species was considerably higher in the refined plots than in non treated plot, the heavily refined plot showing a much higher production than the lightly refined plot. The development of the smaller diameter classes of trees of commercial species was aiso more favorable in the refined plots than in the non treated plotSixteen years after the first logging the bole volume allows already a second harvest in all three plots. However, in-the two refined plots the increment has been favorable in all diameter classes, whereas in the non treated plot the increment occurred only in the higher diameter classes so that a lack of
reserves of timber growing stock after a second harvest can be predicted for this stand. The missing of a second silvicultural refinement ten years after the exploitation as planned originally became visible in the smaller diameter classes. A lot of ingrown trees of non commercial species were found competing with the trees of commercial species. Therefore a second refinement seems to bc advisable to keep a better level of production in the smaller diameter classes. For the investigated plots a harvest cycle of 25 years was predicted. Considering the production in these forest stands felling cycles could bc shorter. For this reason a conclusion is that the silvicultural management of a stand (duration of the feeling cycles and level of exploitation and treatments) should be adapted to the given situation of the forest.(Résumé scannérisé)