Selectively logged tropical forests retain valuable biodiversity, carbon stocks, and – if well-managed – timber resources. This is the main message of a review just published in Conservation Letters. The authors reviewed over 100 studies in which environmental values and timber stocks of logged forests were quantified. The conclusion goes well beyond the popular view held by environmentalists who insist that strict protection is the only viable form of conservation.
The study was conducted by an international team of 12 scientists led by Francis Putz from the University of Florida, and included Roderick Zagt from Tropenbos International and Pieter Zuidema and Marielos Peña-Claros from Wageningen University. The study was published in Conservation Letters. DOI: 10.1111/j.1755-263X.2012.00242.x Click here for a pdf version of this article.
Logging & biodiversity
The study shows that selectively logged forests can be almost as diverse as undisturbed forest. The species richness of mammals, birds, invertebrates and plants in these forests is 85-100% of that in unlogged forests. Lead author Francis Putz from the University of Florida: “Logged forests are greatly undervalued in the conservation world. Our results show that they should play a more prominent role. They are the ‘middle way’ between deforestation and total protection.” He adds: “We certainly need strictly protected areas in tropical rainforests, but if we put all our effort on the 10-20% of rainforest area that are strictly protected we will miss great opportunities for conservation. The 400 million hectares of tropical forests officially designated for logging already contribute to biodiversity conservation and may do so more if their management is improved.”
The authors recognize that ‘conservation through use’ is a politically charged issue. Putz: “This paper is likely to cause quite a stir in conservation and development circles. But more importantly, I hope it will stimulate interest in sustainable tropical forest management as a viable conservation strategy”.
Logged forests reduce climate change by retaining a large proportion (~80%) of their original carbon stocks, even shortly after trees have been felled. Loss of carbon during felling operations may be substantially reduced when applying careful logging practices. Pieter Zuidema of the Forest Ecology and Forest Management group: “Keeping carbon in logged forests is crucial as this reduces CO2-emissions. Deforestation, fire, and poor management of tropical forests contribute 15-20% of the CO2-emissions worldwide. The UN ‘REDD+’ initiative that aims to reduce these emissions can provide important incentives for more careful treatment of tropical forests.”
Logged forests will deliver lower volumes of timber during the next round of exploitation. The reviewed studies indicate that timber yields available after 20-40 years are 50% of the volume obtained during the first harvest. Marielos Peña-Claros, also at the Forest Ecology and Forest Management group: “Timber yields can be substantially increased if the growth of small valuable trees is stimulated by freeing them from lianas and by removing other competitors. In Bolivian forests we have shown that these practices increase growth rates by up to 58%.”
The authors are optimistic about the prospects of managed forests to continue supplying timber, supporting local development, and reducing the effects of climate change. Marielos Peña-Claros is convinced that several new international initiatives will improve tropical forest management. “Certification of good management practices, such as by the Forest Stewardship Council (FSC), will become more important. In addition, the recent EU policies that require tropical timber to be from legal origins, the so-called FLEGT program, will also give a boost to responsible forest management”. Roderick Zagt of Tropenbos International points to a third factor that stimulates forest management: “In large areas the control over rainforests has been handed back to indigenous peoples and rural communities. This small-scale management of forests is often better and more sustainable in the long run, and helps reduce poverty.”
Putz, F. E., Zuidema, P. A., Synnott, T., Peña-Claros, M., Pinard, M. A., Sheil, D., Vanclay, J. K., Sist, P., Gourlet-Fleury, S., Griscom, B., Palmer, J. and Zagt, R. (2012), Sustaining conservation values in selectively logged tropical forests: the attained and the attainable. Conservation Letters. doi: 10.1111/j.1755-263X.2012.00242.x