Road map to save environment
A global map highlights regions where road construction will have high environmental costs
INDIA PLANS to construct over 0.8 million kilometres of roads by 2025 to connect every habitat in the country, as per the targets outlined in the government's Rural Road Development Vision. Worldwide, 25 million kilometres of roads are proposed to be constructed by 2050—a 60 per cent increase in road length from 2010—and ninetenths of this new construction is expected in developing countries such as India. But construction of roads often harms biodiversity and destroys wild habitat. To weigh the potential benefits associated with road construction against their environmental impact,William Laurance,professor at James Cook University, Australia, and colleagues conducted a study and came up with a map that can help policymakers take informed decisions on where to construct roads.
The map highlights regions where road constructions will have high environmental costs.It is based on two factors: environmental values and road benefits. Environmental values are measured by integrating global data on three classes of parameters: biodiversity, key wilderness habitats and carbon storage and climate-regulation services of the local ecosystem. The researchers assigned a value between zero and one to each part of the globe. Regions with sensitive environments and, therefore, high environmental value scored close to one on a scale of zero to one. Similarly, road benefits were defined on the basis of potential increase in agricultural production resulting from better connectivity offered by roads.
The two sets of data were combined to generate a global map where every square kilometre (sq km) has been assigned a colour (see map). Green areas are those where road building would have relatively high environmental costs and only modest potential benefits for agriculture, while red-shaded areas have a high potential to increase agricultural production and low environmental values. Large parts of the Indian
subcontinent fall under this category. Black and dark-shaded areas are “conflict zones” with high values on both the parameters, whereas white and light-shaded areas are of lower priority for both environment and agriculture.
In countries such as Indonesia and Madagascar, which have been assigned “exceptional environmental value”, the authors suggest adoption of alternative methods,such as ecotourism and harvesting the forest produce, to meet economic development goals.
The authors note that roads are being constructed or are planned in regions that have high environmental values but only modest agricultural potential.These regions include the Amazon Basin,parts of the AsiaPacific region and high latitude forests in the Northern Hemisphere.The map also shows that regions where road making is environmentally feasible exist in every continent.In total 12.3 per cent of the global land area has been mapped red.These include parts of central Eurasia,the Irano-Anatolian region, African Sahel and the Indian subcontinent. The study was published in Nature on August 27
What ails India
What does the study mean for countries such as India which the map says has a huge scope for constructing roads with minimal environmental impact? According to Laurance,road construction even in such areas will have environmental impact (see ` Unplanned roads can cause a lot of damage'). There are several examples to show this. Sanjay Gubbi of Mysore-based non-profit Nature Conservation Foundation says 23 leopards have died in road accidents in Karnataka in the past five years. He says environmental impact assessments done before laying new roads often ignore ecological issues resulting in loss of biodiversity and animal habitat.But this can be easily avoided.
Gubbi worked with the state government to realign a part of the MysoreMananthavadi road passing through the Nagarahole Tiger Reserve. “The realigned road helps 'defragment' wildlife habitat in addition to providing connectivity to 11 villages,”he says.
Red shades highlight areas where road construction will benefit agriculture and have minor environmental costs, while green shades denote areas where roads will have high environmental costs and low agricultural benefits