Carbon credits and the conservation of natural areas

摘要

Increasing the amount of organic-carbon stored in the biomass of terrestrial ecosystems is an effective way tonreduce the net anthropogenic emissions of greenhouse gases to the atmosphere. This can be done by conserving existingnecological reservoirs of fixed organic-carbon, maintaining or enhancing the rate of sequestration, and restoring stocks thatnhave been depleted by past land-use practices. Most trading systems for greenhouse-gas offsets recognize the validity ofnprojects that gain ecological offsets, and permit them to sell carbon credits in an emerging marketplace for these novelncommodities. Although ecological carbon-offset projects have been criticized from a variety of perspectives, most of thensupposed problems can be satisfactorily mitigated. In addition to offsetting emissions of greenhouse gases, ecological proj-nects that accumulate carbon credits may have a strong cross-linkage to the conservation of natural values, which in itselfnis an important action for society to undertake. This is, however, less of a consideration for projects that are based onnanthropogenic ecosystems, such as no-till agricultural systems and plantation forests, which provide relatively few benefitsnto native biodiversity and might even detract from that objective if developed on newly converted natural habitat. More-nover, the existing rules for carbon-offset systems exclude some kinds of ecological projects from the trading markets, evennthough they would result in avoided emissions or enhanced sequestration of organic-carbon. As the emerging marketplacenfor carbon offsets grows, it will be important to understand the co-benefits and side effects of offset projects on non-car-nbon values, including native biodiversity