Anthropogenic disturbance in tropical forests can double biodiversity loss from deforestation

Abstract

Concerted political attention has focused on reducing deforestation, and this remains the cornerstone of most biodiversity conservation strategies. However, maintaining forest cover may not reduce anthropogenic forest disturbances, which are rarely considered in conservation programmes. These disturbances occur both within forests, including selective logging and wildfires, and at the landscape level, through edge, area and isolation effects. 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 Pará. 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, 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 Pará, which covers 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared with deforested areas, the toll of disturbance outside Pará’s strictly protected areas is equivalent to the loss of 92,000–139,000 km2 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.

The value of trophic interactions for ecosystem function: dung beetle communities influence seed burial and seedling recruitment in tropical forests

“…The geographical pattern of species loss is non-random [5], with tropical forests displaying the highest rates of declines in biodiversity [1], caused by unsustainable hunting in conjunction with habitat loss and modification [6][7][8]. Decreases in vertebrate populations within tropical forests are of particular concern because top-down trophic cascades can affect plants through changes & 2016 The Author(s) Published by the Royal Society.…”

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“…An important extension of this work would be to model and explore the drivers of forest loss in NNR and northern Mozambique. There are also many anthropogenic threats and disturbances beyond habitat loss which are affecting NNR's ecological state and biodiversity, such as commercial poaching, overhunting, wildfires, climate change, artisanal mining and selective logging, which our analysis does not capture (Barlow et al, 2016;Maxwell et al, 2016). Bush-meat hunting using snares, which kill indiscriminately, is occurring in NNR, as is the poisoning of large carnivores such as lions and leopards for their body parts (Niassa Carnivore Project, 2015).…”

^240+239Pu depositional signatures as a viable geochronological tool in the Amazon Basin

“…The timeframe of when anthropogenic plutonium was deposited globally closely matches periods of rapid and extensive land use change in the Amazon Basin (Barlow et al, 2016). As such, Pu isotopes may be a valuable tool in assessing sedimentation changes in the Amazon floodplains associated with deforestation and/or urbanization.…”

“…These deposition chronologies were then compared to ~100 year records using natural ( 210 Pb, 226 Ra) radionuclide tracers. The dating methods outlined in this work will be used to form geochronologies during the 20 th century, a timeframe that the Amazon has experienced substantial deforestation and significant changes in sediment loads (Barlow et al, 2016;Rowland et al, 2015).…”