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Combined impacts of deforestation and wildlife trade on tropical biodiversity are severely underestimated - PubMed

  • ️Mon Jan 01 2018

Combined impacts of deforestation and wildlife trade on tropical biodiversity are severely underestimated

William S Symes et al. Nat Commun. 2018.

Abstract

Tropical forest diversity is simultaneously threatened by habitat loss and exploitation for wildlife trade. Quantitative conservation assessments have previously considered these threats separately, yet their impacts frequently act together. We integrate forest extent maps in 2000 and 2015 with a method of quantifying exploitation pressure based upon a species' commercial value and forest accessibility. We do so for 308 forest-dependent bird species, of which 77 are commercially traded, in the Southeast Asian biodiversity hotspot of Sundaland. We find 89% (274) of species experienced average habitat losses of 16% and estimate exploitation led to mean population declines of 37%. Assessing the combined impacts of deforestation and exploitation indicates the average losses of exploited species are much higher (54%), nearly doubling the regionally endemic species (from 27 to 51) threatened with extinction that should be IUCN Red Listed. Combined assessment of major threats is vital to accurately quantify biodiversity loss.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1

Loss-of-habitat in forest-dependent Sundaland birds. Change in suitable habitat, not including the impact of exploitation, for each of the 308 studied species between 2000 and 2015, split by their current IUCN Red-list status: critically endangered (CR), endangered (EN), vulnerable (VU), near threatened (NT), and least concern (LC). The circles represent the extent of suitable habitat in 2000 and the triangles in 2015; the lines are drawn between the circle and triangle for the same species to highlight the species-specific change

Fig. 2
Fig. 2

Illustration of the mapping methodologies showing the impacts of habitat loss and hunting. The three panels illustrate the ranges accessible to trappers for three species in our analysis: a Sumatran Leafbird (Chloropsis media), b Melodious Bulbul (Alophoixus bres) and c White-crowned Hornbill (Berenicornis comatus). The purple line is the outline of the species’ historic range (as provided by BirdLife International). The green area, which is divided into two shades, indicates the total extent of suitable habitat for the species in 2015, once it has been refined for current forest extent and elevation. The dark green regions are areas that are further than 5 km from the forest edge and considered inaccessible to trappers; the light green areas are regions that are within 5 km of a forest edge where exploitation is likely taking place. Species illustrations are not within the CC-BY license of this publication, and instead are reproduced from del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2018). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from

http://www.hbw.com/

on [23/08/2018]). All rights reserved. Basemap: © EuroGeographics for the administrative boundaries

Fig. 3
Fig. 3

Hunting impacts for each of the 77 commercially valuable forest bird species in Sundaland. Each line represents a species and shows the cumulative expected population suppression by exploitation between 0 km and 5 km from forest edge. Lines are coloured by persecution category

Fig. 4
Fig. 4

Combined population declines from habitat loss and exploitation. The blue bar is the contribution of habitat loss and the red bar the contribution of exploitation. This graph only shows the 45 regionally endemic species with a total predicted population decline of over 30% (for all species see supplementary online material). Error bars represent the estimation uncertainty of population decline due to exploitation, they are calculated using the 2.5% and 97.5% intervals of a PERT distribution. Vertical lines represent the thresholds for classification as near threatened (NT) (20%), vulnerable (VU) (30%), endangered (EN) (50%), and critically endangered (CR) (80%). Values above 100% result from adding the effects of habitat loss and exploitation and are interpreted as population declines of 100%

Fig. 5
Fig. 5

Area of suitable habitat inside protected areas. Histogram of the number of regionally endemic forest-dependent bird species (77 in total) against percentage of a species’ range that falls within a protected area (PA; IUCN category I–V); bar colour represents IUCN status based on our analysis. a The percentage of the range within PAs, and b the percentage of the range protected within PAs once exploitation-susceptible areas (i.e., within 5 km of a forest edge) have been removed

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