Data from: Testing the benefits of conservation set-asides for improved habitat connectivity in tropical agricultural landscapes
Data files
Aug 30, 2019 version files 13.26 MB
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Connectivity_simulations.zip
13.17 MB
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HCVA_summary_data.zip
79.07 KB
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Logistic_regression.zip
17.66 KB
Abstract
1. Habitat connectivity is important for tropical biodiversity
conservation. Expansion of commodity crops, such as oil palm, fragments
natural habitat areas, and strategies are needed to improve habitat
connectivity in agricultural landscapes. The Roundtable on Sustainable Palm
Oil (RSPO) voluntary certification system requires that growers identify
and conserve forest patches identified as High Conservation Value Areas
(HCVAs) before oil palm plantations can be certified as sustainable. We
assessed the potential benefits of these conservation set-asides for forest
connectivity.
2. We mapped HCVAs and quantified their forest cover in 2015. To assess
their contribution to forest connectivity, we modelled range expansion of
forest-dependent populations with five dispersal abilities spanning those
representative of poor dispersers (e.g., flightless insects) to more mobile
species (e.g., large birds or bats) across 70 plantation landscapes in
Borneo.
3. Because only 21% of HCVA area was forested in 2015, these conservation
set-asides currently provide few connectivity benefits. Compared to a
scenario where HCVAs contain no forest (i.e., a no-RSPO scenario), current
HCVAs improved connectivity by ~3% across all dispersal abilities. However,
if HCVAs were fully reforested, then overall landscape connectivity could
improve by ~16%. Reforestation of HCVAs had the greatest benefit for poor
to intermediate dispersers (0.5-3 km per generation), generating landscapes
that were up to 2.7 times better connected than landscapes without HCVAs.
By contrast, connectivity benefits of HCVAs were low for highly mobile
populations under current and reforestation scenarios, because range
expansion of these populations was generally successful regardless of the
amount of forest cover.
4.Synthesis and applications. The RSPO requires that HCVAs be set
aside to conserve biodiversity, but HCVAs currently provide few
connectivity benefits because they contain relatively little forest.
However, reforested HCVAs have the potential to improve landscape
connectivity for some forest species (e.g., winged insects), and we
recommend active management by plantation companies to improve forest
quality of degraded HCVAs (e.g., by enrichment planting). Future revisions
to the RSPO’s Principles and Criteria (P&C) should also ensure that large
(i.e., with a core area >2 km2) HCVAs are reconnected to continuous tracts
of forest to maximise their connectivity benefits.