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Concerted political attention has focused on reducing deforestation (1-3), and this remains the cornerstone of most biodiversity conservation strategies (4-6). However, maintaining forest cover may not reduce anthropogenic forest disturbances, which are rarely considered in conservation programmes (6). These disturbances occur both within forests, including selective logging and wildfires (7,8), and at the landscape level, through edge, area and isolation effects (9). Until now, the combined effect of anthropogenic disturbance on the conservation value of remnant primary forests has remained unknown, making it impossible to assess the relative importance of forest disturbance and forest loss. Here we address these knowledge gaps using a large data set of plants, birds and dung beetles (1,538, 460 and 156 species, respectively) sampled in 36 catchments in the Brazilian state of Para. Catchments retaining more than 69-80% forest cover lost more conservation value from disturbance than from forest loss. For example, a 20% loss of primary forest, the maximum level of deforestation allowed on Amazonian properties under Brazil's Forest Code (5), resulted in a 39-54% loss of conservation value: 96-171% more than expected without considering disturbance effects. We extrapolated the disturbance-mediated loss of conservation value throughout Para, which covers 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared with deforested areas, the toll of disturbance outside Para's strictly protected areas is equivalent to the loss of 92,000-139,000 [km.sup.2] of primary forest. Even this lowest estimate is greater than the area deforested across the entire Brazilian Amazon between 2006 and 2015 (ref. 10). Species distribution models showed that both landscape and within-forest disturbances contributed to biodiversity loss, with the greatest negative effects on species of high conservation and functional value. These results demonstrate an urgent need for policy interventions that go beyond the maintenance of forest cover to safeguard the hyper-diversity of tropical forest ecosystems., Protecting tropical forests is a fundamental pillar of many national and international strategies for conserving biodiversity (4-6). Although improved regulatory and incentive measures have reduced deforestation rates in some tropical [...]

Brazil's Environmental Council of Para State (COEMA) is debating a resolution to the new Brazilian Forest Code that will help to define 'low-impact' land uses in legally designated areas of [...]

Background:Patterns in tropical forest nitrogen cycling are poorly understood. In particular, the extent to which leguminous trees in these forests fix nitrogen is unclear. Aims:We aimed to determine factors that explain variation in foliar δ15N (δ15NF) for Amazon forest trees, and to evaluate the extent to which putatively N2-fixing Fabaceae acquire nitrogen from the atmosphere. Methods:Upper-canopy δ15NFvalues were determined for 1255 trees sampled across 65 Amazon forest plots. Along with plot inventory data, differences in δ15NFbetween nodule-forming Fabaceae and other trees were used to estimate the extent of N2fixation. Results:δ15NFranged from −12.1‰ to +9.3‰. Most of this variation was attributable to site-specific conditions, with extractable soil phosphorus and dry-season precipitation having strong influences, suggesting a restricted availability of nitrogen on both young and old soils and/or at low precipitation. Fabaceae constituted fewer than 10% of the sampled trees, and only 36% were expressed fixers. We estimated an average Amazon forest symbiotic fixation rate of 3 kg N ha−1year−1. Conclusion:Plant δ15N indicate that low levels of nitrogen availability are only likely to influence Amazon forest function on immature or old weathered soils and/or where dry-season precipitation is low. Most Fabaceae species that are capable of nodulating do not fix nitrogen in Amazonia. [ABSTRACT FROM PUBLISHER]