critical impacts of roads on tropical forests and their carbon stocks

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

625 times

International Energy Agency (2013)

25 million km new roads by 2050

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

Direct EffectsHabitat Loss

Road kill

Vulnerable species• slow-moving• poor eyesight• freeze response• forage along roads• basking species• mass migrators

Secondary Effects

Laurance et al. (2006, 2008) Conservation BiologyLaurance (2010) Africa Geographic Magazine

Incursions of hunters

Bolivia

Adeney et al. (2009) PLoS One

Forest fires

Roads are profilerating

wildly: We direly need strategic road

planning & evaluation

A Global Strategy for Road Buiding

(www.global-roadmap.org)

Laurance & Balmford (2013) NatureLaurance et al. (2014) NatureLaurance et al. (2015a) Current Biology

Africa’s ‘Development Corridors’

33 corridors planned or being upgraded

> 53,000 km in length

Laurance et al. (2015b) Current Biology

Persistent nightlights

Very low threshold used

Human Occupancy

Most corridors only sparsely

populated

‘Natural Values’

Laurance et al. (2014) Nature

Biodiversity1. No. threatened vertebrate species

2. Plant species per ecoregion

Key Habitats1. Biodiversity

Hotspots2. Important Bird Areas

3. G200 Terr. Ecosystems

4. High-biodiv.Wildernesses

Environmental Services1. Losable

carbon2. Climate regulation

Potential Road Benefits1. Converted

land2. Yield

gaps3. Agricult. increases

4. Access to markets

5. Soils & climate

Laurance et al. (2014) Nature

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

‘Promising’‘Marginal’‘Inadvisable’

Laurance et al. (2015b) Current Biology

Crucial need for better

data on tropical

roads

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

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

E.U. InitiativeRoadLess

ForestCombining

remote-sensing data &

crowdsourcing www.roadlessforest.org

See Steve Peedell, Frédéric Achard & Kriton

Arsenis for more info

Thank you