Tropical forests are incredibly biodiverse; they support at least two-thirds of the world’s biodiversity (1) despite covering less than 10% of Earth’s land surface (2). Unfortunately, prospects for tropical forests and the biodiversity therein are becoming increasingly bleak owing to unabated deforestation and forest alteration (3) that stem from human activities such as logging, hunting, agricultural expansion, and human settlement (4, 5) (Fig. 1). Previous studies have summarized how local or subregional biodiversity values differ across primary forests and other land-use types (6, 7), but it is unclear how site- and landscape-level impacts scale up globally. In PNAS, Alroy (8) addresses this challenge by compiling and analyzing a pantropical dataset of 875 local species assemblages sampled in primary forest and 10 other land-use types previously converted from forest. Human activities that threaten tropical forests and the biodiversity therein. (A) Logging in Peninsular Malaysia. (B) Oil palm monoculture in Kalimantan, Indonesia. (C) Cattle grazing on pastures converted from forests in Mato Grosso, Brazil. (D) Smallholder cropping (of cassava) in Loreto, Peru. (E) Harvesting of wood for charcoal production in Benin. (F) Hunting threatens many forest species, including the Malayan tiger caught here on a camera trap in Peninsular Malaysia. Photographs courtesy of Rimba (A and F), X.G. (B), Jacob Socolar (C and D), and Orou Gaoue (E). The task of estimating global biodiversity losses that accrue with tropical deforestation might seem straightforward at first. For example, one might approach this problem by collating global distributions of different taxa, removing increasing extents of forest, and then counting the extinctions that accumulate when entire species ranges become deforested. This approach suffers from a number of pitfalls. First, it assumes populations originally occurring in forests can never survive in altered habitats. Indeed, it is well documented that altered forests and other …

In the last few decades, there has been a remarkable discovery of new species of plants, invertebrates and vertebrates, in what have been called the new age of discovery. However, owing to anthropogenic impacts such as habitat conversion, many of the still unknown species may go extinct before being scientifically documented (i.e. ‘crypto-extinctions’). Here, by applying a mathematical model of species descriptions which accounts for taxonomic effort, we show that even after 250 years of taxonomic classification, about 3050 amphibians and at least 160 land mammal species remain to be discovered and described. These values represent, respectively, 33 and 3 per cent of the current species total for amphibians and land mammals. We found that tropical moist forests of the Neotropics, Afrotropics and Indomalaya probably harbour the greatest numbers of undescribed species. Tropical forests with minimal anthropogenic disturbance are predicted to have larger proportions of undescribed species. However, the protected area coverage is low in many of these key biomes. Moreover, undescribed species are likely to be at a greater risk of extinction compared with known species because of small geographical ranges among other factors. By highlighting the key areas of undescribed species diversity, our study provides a starting template to rapidly document these species and protect them through better habitat management.

Environmental protection is critical to maintain ecosystem services essential for human well-being. It is important to be able to rank countries by their environmental impact so that poor performers as well as policy ‘models’ can be identified. We provide novel metrics of country-specific environmental impact ranks – one proportional to total resource availability per country and an absolute (total) measure of impact – that explicitly avoid incorporating confounding human health or economic indicators. Our rankings are based on natural forest loss, habitat conversion, marine captures, fertilizer use, water pollution, carbon emissions and species threat, although many other variables were excluded due to a lack of country-specific data. Of 228 countries considered, 179 (proportional) and 171 (absolute) had sufficient data for correlations. The proportional index ranked Singapore, Korea, Qatar, Kuwait, Japan, Thailand, Bahrain, Malaysia, Philippines and Netherlands as having the highest proportional environmental impact, whereas Brazil, USA, China, Indonesia, Japan, Mexico, India, Russia, Australia and Peru had the highest absolute impact (i.e., total resource use, emissions and species threatened). Proportional and absolute environmental impact ranks were correlated, with mainly Asian countries having both high proportional and absolute impact. Despite weak concordance among the drivers of environmental impact, countries often perform poorly for different reasons. We found no evidence to support the environmental Kuznets curve hypothesis of a non-linear relationship between impact and per capita wealth, although there was a weak reduction in environmental impact as per capita wealth increases. Using structural equation models to account for cross-correlation, we found that increasing wealth was the most important driver of environmental impact. Our results show that the global community not only has to encourage better environmental performance in less-developed countries, especially those in Asia, there is also a requirement to focus on the development of environmentally friendly practices in wealthier countries.