| 英文摘要: | Reducing tropical deforestation has huge potential for mitigating climate change and saving the Earth's most biologically diverse biome. Corridors connecting existing protected areas represent an elegant means of attaining both goals. In Poland last year, climate negotiators finally agreed to a mechanism for paying developing countries for reducing their forest-based emissions — which account for roughly 15% of global emissions. With pitch-perfect timing, Jantz and colleagues1 propose, in this issue of Nature Climate Change, a framework for harnessing these funds to contribute to biodiversity conservation in the tropics. In their paper they demonstrate that by carefully targeting carbon funds at corridors linking existing protected areas, large benefits can be gained for biodiversity conservation without compromising the new mechanism's primary aim of slowing anthropogenic climate change. The carbon mechanism is termed REDD+ (Reducing Emissions from Deforestation and Forest Degradation, plus the conservation, sustainable management and enhancement of forest carbon stocks), and it is expected to generate unprecedented funding for conservation in the tropics. As tropical forests are home to roughly half of the world's species2, REDD+ has also been heralded as a potential boon for biodiversity conservation3. But carbon and biodiversity 'hotspots' don't always overlap, and the general consensus of recent studies is that tapping into potential biodiversity benefits will require the development of biodiversity-friendly methods for implementing REDD+4. Diverting carbon funds to projects or locations that are good for biodiversity can have drawbacks. It can either directly increase the financial costs of carbon projects or simply overburden them with additional obligations5. To focus on corridors, as suggested by Jantz and colleagues, seems a promising solution. Corridors often yield benefits to biodiversity disproportionate to their size, by increasing population connectivity6 and providing safe routes for species to move with a changing climate7, and could therefore offer a uniquely efficient way of increasing the biodiversity benefits of REDD+. What Jantz and colleagues are suggesting in their paper is elegantly simple: invest in corridors between protected areas that traverse locations (1) high in vegetation carbon stock, (2) rich in species and (3) with low value for other economic opportunities, thereby minimizing conflict with competing land uses. Using a recent high-resolution map of vegetation carbon density8, they go on to demonstrate how this framework can be implemented by creating a pan-tropical map of corridors, and also a more detailed map for the Amazon. What they find is encouraging. Most importantly, investing in corridors can contribute to maintaining vegetation carbon stores. In Africa, for instance, they find that the corridors they identified stored 130 tonnes of carbon per hectare, which is substantially more than the protected areas they link. On the other hand, the authors do caution that corridors are not necessarily the most efficient path to capturing carbon. They find that by ignoring their corridor framework and instead investing in the most carbon-dense parts of the tropics, it is possible to protect the same amount of carbon in less area. But reducing carbon emissions is about more than just protecting high carbon stores. To actually reduce emissions, those stores must be at risk of being lost through land-cover change. Because corridors typically traverse more fragmented landscapes, the authors find that carbon captured within them tends to be at greater risk of being lost than areas identified in the non-corridor approach. So although corridors may not be the most carbon-dense real estate, they are at risk of conversion and are therefore good places for reducing future land-based emissions. Jantz and colleagues are the first to suggest using corridors for implementing REDD+, and thus open up a new area for future studies. For instance, one of the primary benefits of corridors is to assist climate-induced shifts in species ranges. To maximize this benefit, one might consider expanding the framework developed by Jantz et al. to identify corridors that not only pass through biodiversity-rich habitats, but also traverse important environmental gradients, such as rainfall or elevation. Moreover, much of a corridor's value lies in the protected areas it connects, so identifying corridors connecting two or more protected areas that are rich in species could also be beneficial. The largest question left unanswered may be exactly how REDD+ corridors should be managed. Over the past decade, conservation has shifted towards greater alignment of conservation outcomes with enhancing human well-being. This is often best pursued by emphasizing local stakeholders and decision makers9. Unlike protected areas, which must typically be managed following a defined structure, the door is wide open for how corridors can best be managed to promote multiple benefit and long-term viability. An obvious contender for managing corridors could be through certified reduced impact logging, which allows revenues to be generated while natural values are largely maintained10, or treating them as forest commons that serve to supply timber and non-timber forest products to local resource users11. Given that it has taken eight long years for agreement to be reached on the REDD+ mechanism, exactly how a corridor approach is implemented will probably be debated for some time. Still, Jantz and colleagues1 have shown us that such an approach would have benefits for the climate, and for biodiversity.
- Jantz, P., Goetz, S. & Laporte, N. Nature Clim. Change 4, 138–142 (2014).
- Wilson, E. O. The Diversity of Life (Belknap, 1992).
- Venter, O. et al. Science 326, 1368 (2009).
- Gardner, T. A. et al. Biol. Conserv. 154, 61–71 (2012).
- Harvey, C. A., Dickson, B. & Kormos, C. Conserv. Lett 3, 53–61 (2010).
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- Williams, P. et al. Conserv. Biol. 19, 1063–1074 (2005).
- Baccini, A. et al. Nature Clim. Change 2, 182–185 (2012).
- Naughton-Treves, L., Holland, M. B. & Brandon, K. T. Annu. Rev. Environ. Res. 30, 219–252 (2005).
- Putz, F. E. et al. PLoS Biol. 6, e166 (2008).
- Chhatre, A. & Agrawal, A. Proc. Natl Acad. Sci. USA 106, 17667–17670 (2009).
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Affiliations
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Oscar Venter is at the Centre for Tropical Environmental and Sustainability Science, and the School of Marine and Tropical Biology, James Cook University, Cairns, Queensland 4878, Australia
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