Can tropical silvicultural interventions improve the sustainability of timber production while ensuring the conservation of production forests?
Lead reviewers: Plinio Sist, French Agricultural Research Centre for International Development (CIRAD)
Collaborating institutions: Center for International Forestry Research (CIFOR), Wageningen University, University of Florida, Bangor University, University of Liège
Systematic review protocol: Environmental Evidence 2015, 4:8
We are seeing a gradual impoverishment of forest resources inside tropical forests that were selectively logged 30–40 years ago. In these forests, the volume of timber extracted over the first cutting cycle was mostly from large trees that grew over several centuries in the absence of strong anthropogenic pressures. Today, in many forests likely to be logged for the second felling cycle, that volume has not been reconstituted and, in many cases, the young trees expected to make up the next harvest are largely lacking in numbers as no silvicultural treatments have been undertaken.
With around 400 million ha of tropical moist forests designated as production forests worldwide, this poor stand structure puts them at risk of being severely degraded and ultimately converted to other uses. The problem was highlighted by foresters in the 1960s who undertook a large variety of silvicultural trials in Africa and Southeast Asia with a view to enriching tropical forests with commercial species by fostering their regeneration either naturally or artificially. Those trials generated a considerable amount of data and knowledge that has mostly remained confidential, published in technical reports and/or non-English language journals, and fully under-valued — or even forgotten — as logging has turned out to be a vastly cost-effective operation in most forests dedicated to production.
A systematic review of the impact of past silvicultural practices, and not just logging, could tell us much about the challenges of the future in valuing these logged over forests usually considered degraded and therefore apt for conversion. Indeed, whilst various post-logging silvicultural treatments have been tested in the tropics for decades, they were abandoned in the 80s to the benefit of selective logging. The main objective of this systematic review is therefore to assess past knowledge of the impact of silviculture in tropical forests and to identify silvicultural rules adapted to the current conditions in the forests and forestry sectors of three regions: the Congo Basin, Amazonia and Southeast Asia.