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William F. Laurance
Director Centre for Tropical
Environmental and Sustainability Science
James Cook University Australia - Singapore
Critical Impacts of Roads on Tropical Forests and
their Carbon Stocks
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625 times
International Energy Agency (2013)
25 million km new roads by 2050
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7,500 km of new highways in Brazilian Amazon
Triad of highways from Amazon to Pacific Ocean
52,000 km of new logging roads in Congo Basin
New roads opening up last intact forests in Sumatra
$150 million for new roads in Indonesian New Guinea
Many roads bisecting protected areas
90% of new roads in developing
nations
Laurance et al. (2009) Trends in Ecology & EvolutionLaurance (2009) New ScientistLaurance (2012) Yale Environment 360Laurance & Balmford (2013) Nature
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Direct EffectsHabitat Loss
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Road kill
Vulnerable species• slow-moving• poor eyesight• freeze response• forage along roads• basking species• mass migrators
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Secondary Effects
Laurance et al. (2006, 2008) Conservation BiologyLaurance (2010) Africa Geographic Magazine
Incursions of hunters
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Bolivia
Adeney et al. (2009) PLoS One
Forest fires
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Roads are profilerating
wildly: We direly need strategic road
planning & evaluation
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A Global Strategy for Road Buiding
(www.global-roadmap.org)
Laurance & Balmford (2013) NatureLaurance et al. (2014) NatureLaurance et al. (2015a) Current Biology
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Africa’s ‘Development Corridors’
33 corridors planned or being upgraded
> 53,000 km in length
Laurance et al. (2015b) Current Biology
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Persistent nightlights
Very low threshold used
Human Occupancy
Most corridors only sparsely
populated
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‘Natural Values’
Laurance et al. (2014) Nature
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Biodiversity1. No. threatened vertebrate species
2. Plant species per ecoregion
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Key Habitats1. Biodiversity
Hotspots2. Important Bird Areas
3. G200 Terr. Ecosystems
4. High-biodiv.Wildernesses
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Environmental Services1. Losable
carbon2. Climate regulation
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Potential Road Benefits1. Converted
land2. Yield
gaps3. Agricult. increases
4. Access to markets
5. Soils & climate
Laurance et al. (2014) Nature
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Conservation priority vs. potential road-benefits
Many corridors have high conservation priority
Six high-conservation corridors also have limited agricultural potential
Promising
Marginal
Marginal
Inadvisable
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‘Promising’‘Marginal’‘Inadvisable’
Laurance et al. (2015b) Current Biology
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Crucial need for better
data on tropical
roads
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Roads & deforestation
0
20
40
60
80
100
0 100 200 300 400 500 600
y = 70.18 - 26.16log(x) R= 0.6569
Def
ores
tatio
n (%
)
Distance to highway (km)
Laurance et al. (2002) Journal of Biogeography
Effects of ‘official’
paved roads
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Including illegal roads
Barber, Cochrane, Souza & Laurance (2014) Biological Conservation
Detailed mapping of all roads Nearly 3 km of illegal roads for
every 1 km of legal road Much tighter relationship
between roads & deforestation
5.5 km
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E.U. InitiativeRoadLess
ForestCombining
remote-sensing data &
crowdsourcing www.roadlessforest.org
See Steve Peedell, Frédéric Achard & Kriton
Arsenis for more info
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Thank you