Endangered tigers face growing threats from an Asian road-building boom

Female tiger crossing track, Bandavgarh National Park, India.
David Tipling/Universal Images Group/Getty Images

Neil Carter, University of Michigan

Tigers are one of the world’s most iconic wild species, but today they are endangered throughout Asia. They once roamed across much of this region, but widespread habitat loss, prey depletion and poaching have reduced their numbers to only about 4,000 individuals. They live in small pockets of habitat across South and Southeast Asia, as well as the Russian Far East – an area spanning 13 countries and 450,000 square miles (1,160,000 square kilometers).

Today Asia is experiencing a road-building boom. To maintain economic growth, development experts estimate that the region will need to invest about US$8.4 trillion in transportation infrastructure between 2016 and 2030.

Major investment projects, such as China’s Belt and Road Initiative – one of the largest infrastructure projects of all time – are fueling this growth. While roads can reduce poverty, especially in rural areas, many of Asia’s new roads also are likely to traverse regions that are home to diverse plants and animals.

To protect tigers from this surge of road building, conservation scientists like me need to know where the greatest risks are. That information, in turn, can improve road planning in the future.

In a newly published study, I worked with researchers at the University of Michigan, Boise State University and the University of British Columbia to examine how existing and planned Asian roads encroach on tiger habitats. We forecast that nearly 15,000 miles (24,000 kilometers) of new roads will be built in tiger habitats by 2050, and call for bold new planning strategies that prioritize biodiversity conservation and sustainable road development across large landscapes.

Economic growth in Asia means more roads will be built into tiger habitat. Planning at the outset can make these projects more tiger-friendly.

Letting humans in

Road construction worsens existing threats to tigers, such as poaching and development, by paving the way for human intrusion into the heart of the tiger’s range. For example, in the Russian Far East, roads have led to higher tiger mortality due to increased collisions with vehicles and more encounters with poachers.

To assess this threat across Asia, we focused on areas called Tiger Conservation Landscapes – 76 zones, scattered across the tiger’s range, which conservationists see as crucial for the species’ recovery. For each zone we calculated road density, distance to the nearest road and relative mean species abundance, which estimates the numbers of mammals in areas near roads compared to areas far from roads. Mean species abundance is our best proxy for estimating how roads affect numbers of mammals, like tigers and their prey, across broad scales.

We also used future projections of road building in each country to forecast the length of new roads that might be built in tiger habitats by 2050.

Overpasses and underpasses, like this one in Florida, help wild animals traverse highways safely.

More roads, fewer animals

We estimated that more than 83,300 miles (134,000 kilometers) of roads already exist within tiger habitats. This is likely an underestimate, since many logging or local roads are missing from the global data set that we used.

Road densities in tiger habitat are one-third greater outside of protected areas, such as national parks and tiger reserves, than inside of protected areas. Non-protected areas averaged 1,300 feet of road per square mile (154 meters per square kilometer), while protected areas averaged 980 feet per square mile (115 meters per square kilometer). For tiger populations to grow, they will need to use the forests outside protected areas. However, the high density of roads in those forests will jeopardize tiger recovery.

Protected areas and priority conservation sites – areas with large populations of tigers – are not immune either. For example, in India – home to over 70% of the world’s tigers – we estimate that a protected area of 500 square miles, or 1,300 square kilometers, contains about 200 miles (320 kilometers) of road.

Road networks are expansive. Over 40% of areas where tiger breeding has recently been detected – crucial to tiger population growth – is within just 3 miles (5 kilometers) of a nearby road. This is problematic because mammals often are less abundant this close to roads.

In fact, we estimate that current road networks within tiger habitats may be reducing local populations of tigers and their prey by about 20%. That’s a major decrease for a species on the brink of extinction. And the threats from roads are likely to become more severe.

Estimated road densities for 76 tiger conservation landscapes (colored zones), with darker red indicating more roads per unit area.
Neil Carter, CC BY-ND

Making infrastructure tiger-friendly

Our findings underscore the need for planning development in ways that interfere as minimally as possible with tiger habitat. Multilateral development banks and massive ventures like the Belt and Road Initiative can be important partners in this endeavor. For example, they could help establish an international network of protected areas and habitat corridors to safeguard tigers and many other wild species from road impacts.

National laws can also do more to promote tiger-friendly infrastructure planning. This includes keeping road development away from priority tiger populations and other “no go” zones, such as tiger reserves or habitat corridors.

Zoning can be used around infrastructure to prevent settlement growth and forest loss. Environmental impact assessments for road projects can do a better job of assessing how new roads might exacerbate hunting and poaching pressure on tigers and their prey.

Funding agencies need to screen proposed road developments using these tiger-friendly criteria before planners finalize decisions on road design, siting and construction. Otherwise, it might be too late to influence road planning.

There are also opportunities to reduce the negative effects of existing roads on tigers. They include closing roads to vehicular traffic at night, decommissioning existing roads in areas with important tiger populations, adding road signs announcing the presence of tigers and constructing wildlife crossings to allow tigers and other wildlife to move freely through the landscape.

Roads will become more pervasive features in Asian ecosystems as these nations develop. In my view, now is the time to tackle this mounting challenge to Asian biodiversity, including tigers, through research, national and international collaborations and strong political leadership.

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Neil Carter, Assistant Professor of Wildlife Conservation, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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The global road-building explosion is shattering nature

Bill Laurance, James Cook University

If you asked a friend to name the worst human threat to nature, what would they say? Global warming? Overhunting? Habitat fragmentation?

A new study suggests it is in fact road-building.

“Road-building” might sound innocuous, like “house maintenance” – or even positive, conjuring images of promoting economic growth. Many of us have been trained to think so.

But an unprecedented spate of road building is happening now, with around 25 million kilometres of new paved roads expected by 2050. And that’s causing many environmental researchers to perceive roads about as positively as a butterfly might see a spider web that’s just fatally trapped it.

A Malayan tapir killed along a road in Peninsular Malaysia.
WWF-Malaysia/Lau Ching Fong

Shattered

The new study, led by Pierre Ibisch at Eberswalde University for Sustainable Development, Germany, ambitiously attempted to map all of the roads and remaining ecosystems across Earth’s entire land surface.

Its headline conclusion is that roads have already sliced and diced Earth’s ecosystems into some 600,000 pieces. More than half of these are less than 1 square kilometre in size. Only 7% of the fragments are more than 100 square km.

Remaining roadless areas across the Earth.
P. Ibisch et al. Science (2016)

That’s not good news. Roads often open a Pandora’s box of ills for wilderness areas, promoting illegal deforestation, fires, mining and hunting.

In the Brazilian Amazon, for instance, our existing research shows that 95% of all forest destruction occurs within 5.5km of roads. The razing of the Amazon and other tropical forests produces more greenhouse gases than all motorised vehicles on Earth.

Animals are being imperilled too, by vehicle roadkill, habitat loss and hunting. In just the past decade, poachers invading the Congo Basin along the expanding network of logging roads have snared or gunned down two-thirds of all forest elephants for their valuable ivory tusks.

Deforestation along roads in the Brazilian Amazon.
Google Earth

Worse than it looks

As alarming as the study by Ibisch and colleagues sounds, it still probably underestimates the problem, because it is likely that the researchers missed half or more of all the roads on the planet.

That might sound incompetent on their part, but in fact keeping track of roads is a nightmarishly difficult task. Particularly in developing nations, illegal roads can appear overnight, and many countries lack the capacity to govern, much less map, their unruly frontier regions.

One might think that satellites and computers can keep track of roads, and that’s partly right. Most roads can be detected from space, if it’s not too cloudy, but it turns out that the maddening variety of road types, habitats, topographies, sun angles and linear features such as canals can fool even the smartest computers, none of which can map roads consistently.

The only solution is to use human eyes to map roads. That’s what Ibisch and his colleagues relied upon – a global crowdsourcing platform known as OpenStreetMap, which uses thousands of volunteers to map Earth’s roads.

Therein lies the problem. As the authors acknowledge, human mappers have worked far more prolifically in some areas than others. For instance, wealthier nations like Switzerland and Australia have quite accurate road maps. But in Indonesia, Peru or Cameroon, great swathes of land have been poorly studied.

A quick look at OpenStreetmap also shows that cities are far better mapped than hinterlands. For instance, in the Brazilian Amazon, my colleagues and I recently found 3km of illegal, unmapped roads for every 1km of legal, mapped road.

A logging truck blazes along a road in Malaysian Borneo.
Rhett Butler/Mongabay

What this implies is that the environmental toll of roads in developing nations – which sustain most of the planet’s critical tropical and subtropical forests – is considerably worse than estimated by the new study.

This is reflected in statistics like this: Earth’s wilderness areas have shrunk by a tenth in just the past two decades, as my colleagues and I reported earlier this year. Lush forests such as the Amazon, Congo Basin and Borneo are shrinking the fastest.

Road rage

The modern road tsunami is both necessary and scary. On one hand, nobody disputes that developing nations in particular need more and better roads. That’s the chief reason that around 90% of all new roads are being built in developing countries.

On the other hand, much of this ongoing road development is poorly planned or chaotic, leading to severe environmental damage.

For instance, the more than 53,000km of “development corridors” being planned or constructed in Africa to access minerals and open up remote lands for farming will have enormous environmental costs, our research suggests.

Orangutans in the wilds of northern Sumatra.
Suprayudi

This year, both the Ibisch study and our research have underscored how muddled the UN Sustainable Development Goals are with respect to vanishing wilderness areas across the planet.

For instance, the loss of roadless wilderness conflicts deeply with goals to combat harmful climate change and biodiversity loss, but could improve our capacity to feed people. These are tough trade-offs.

One way we’ve tried to promote a win-win approach is via a global road-mapping strategy that attempts to tell us where we should and shouldn’t build roads. The idea is to promote roads where we can most improve food production, while restricting them in places that cause environmental calamities.

Part of a global road-mapping strategy. Green areas have high environmental values where roads should be avoided. Red areas are where roads could improve agricultural production. And black areas are ‘conflict zones’ where both environmental values and potential road benefits are high.
W. F. Laurance et al. Nature (2014)

The bottom line is that if we’re smart and plan carefully, we can still increase food production and human equity across much of the world.

But if we don’t quickly change our careless road-building ways, we could end up opening up the world’s last wild places like a flayed fish – and that would be a catastrophe for nature and people too.

Bill Laurance, Distinguished Research Professor and Australian Laureate, James Cook University

This article was originally published on The Conversation. Read the original article.