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Across the tropics, there is a growing financial investment in activities that aim to reduce emissions from deforestation and forest degradation, such as REDD+. However, most tropical countries lack on-the-ground capacity to conduct reliable and replicable assessments of forest carbon stocks, undermining their ability to secure long-term carbon finance for forest conservation programs. Clear guidance on how to reduce the monetary and time costs of field assessments of forest carbon can help tropical countries to overcome this capacity gap. Here we provide such guidance for cost-effective one-off field assessments of forest carbon stocks. We sampled a total of eight components from four different carbon pools (i.e. aboveground, dead wood, litter and soil) in 224 study plots distributed across two regions of eastern Amazon. For each component we estimated survey costs, contribution to total forest carbon stocks and sensitivity to disturbance. Sampling costs varied thirty-one-fold between the most expensive component, soil, and the least, leaf litter. Large live stems (≥10 cm DBH), which represented only 15% of the overall sampling costs, was by far the most important component to be assessed, as it stores the largest amount of carbon and is highly sensitive to disturbance. If large stems are not taxonomically identified, costs can be reduced by a further 51%, while incurring an error in aboveground carbon estimates of only 5% in primary forests, but 31% in secondary forests. For rapid assessments, necessary to help prioritize locations for carbon- conservation activities, sampling of stems ≥20cm DBH without taxonomic identification can predict with confidence (R2 = 0.85) whether an area is relatively carbon-rich or carbon-poor—an approach that is 74% cheaper than sampling and identifying all the stems ≥10cm DBH. We use these results to evaluate the reliability of forest carbon stock estimates provided by the IPCC and FAO when applied to human-modified forests, and to highlight areas where cost savings in carbon stock assessments could be most easily made.

A expansão das plantações de dendezeiros através dos trópicos úmidos precipitou a perda maciça de habitats de florestas tropicais e seus biotas speciose associados. Monoculturas de plantações de dendezeiros foram identificadas como uma ameaça emergente para a biodiversidade amazônica, mas Não há estudos quantitativos que explorem o impacto dessas plantações na biota do bioma. Compreensão esses impactos são extremamente importantes, dada a rápida expansão projetada do petróleo cultivo de palmeira na bacia. Aqui nós investigamos o valor da biodiversidade das plantações de dendezeiros em comparação com outros usos de terra regionais dominantes na Amazônia Oriental. Nós carregamos pesquisas de aves em plantações de dendezeiros de diferentes idades, florestas primárias e secundárias, e pastagens de gado. Descobrimos que as plantações de dendezeiros mantinham comunidades avícolas empobrecidas com uma composição de espécies semelhante a pastagens e usos agrários da terra e não oferecem habitat para a maioria das espécies associadas à floresta, incluindo espécies e espécies de área restrita de preocupação de conservação. Por outro lado, as florestas que as empresas de dendezeiros são legalmente obrigados a proteger abrigou uma comunidade relativamente rica em espécies, incluindo vários espécies de aves ameaçadas. Consideramos que o dendê não é menos prejudicial à biodiversidade regional que outros usos da terra agrícola e que a pressão política exercida por grandes proprietários de terras para permitir que a palma de óleo conte como um substituto para a vegetação de floresta nativa em particular. propriedades rurais com déficits de restauração florestal teriam conseqüências biodiversidade. Expansion of oil palm plantations across the humid tropics has precipitated massive loss of tropical forest habitats and their associated speciose biotas. Oil palm plantation monocultures have been identified as an emerging threat to Amazonian biodiversity, but there are no quantitative studies exploring the impact of these plantations on the biome’s biota. Understanding these impacts is extremely important given the rapid projected expansion of oil palm cultivation in the basin. Here we investigate the biodiversity value of oil palm plantations in comparison with other dominant regional land-uses in Eastern Amazonia. We carried out bird surveys in oil palm plantations of varying ages, primary and secondary forests, and cattle pastures. We found that oil palm plantations retained impoverished avian communities with a similar species composition to pastures and agrarian land-uses and did not offer habitat for most forest-associated species, including restricted range species and species of conservation concern. On the other hand, the forests that the oil palm companies are legally obliged to protect hosted a relatively species-rich community including several globally-threatened bird species. We consider oil palm to be no less detrimental to regional biodiversity than other agricultural land-uses and that political pressure exerted by large landowners to allow oil palm to count as a substitute for native forest vegetation in private landholdings with forest restoration deficits would have dire consequences for regional biodiversity.