Author: Vinni Jain

This is the second article from our four-part series titled, Landscape Connectivity.

Our planet hosts more than 8 million species of bacteria, plants, animals, and fungi. Such extensive biological diversity exists in part due to the sheer variety of environments organisms have adapted to, such as grasslands, forests, caves, and deep seas. Many of these habitats are almost completely cut-off from one another; kangaroos from Australia are unlikely to meet snow leopards from the Himalayas, and freshwater fish are often restricted to a single lake or pond. These barriers to movement or ‘dispersal’ play a major role in shaping Earth’s ecosystems and biodiversity.

As we humans grow in number and modify our surroundings, we are also changing the dispersal patterns of animals and plants by creating new barriers. Asian elephants may once have roamed freely across India through interconnected forests. Today these passages are increasingly blocked by human settlements and infrastructure. Altering dispersal can severely disturb ecological processes and permanently shift biodiversity patterns.

In a recent study published in Land Use Policy, scientists from Foundation for Ecological Research, Advocacy, and Learning (FERAL), Centre for Wildlife Studies, University of Goettingen, and Columbia University examined the impact of infrastructure on forest connectivity across India. They collated and analysed spatial datasets representing existing forest cover and major infrastructure types such as roads, canals, railways, and high tension power-lines.

To evaluate the impact of infrastructure, they compared existing forest patches to simulated versions without any infrastructure. They found that the most common intrusions into forests were major roads (highways and district roads) and high tension power-lines. Infrastructure increased the number of forest patches by 6%, and reduced the number of large forest patches by 71.5%. In Central India, patches were larger, but more isolated, while in the Western Ghats, there was a high number of smaller patches.

This trend poses a risk to biodiversity, as small, isolated forest patches are likely to sustain fewer species and can increase the risk of extinction for resident wildlife. Longer forest edges due to patchiness increases the interface between people and wildlife, leading to a rise in human-wildlife conflict and disease transmission, both of which pose a severe threat to humans.

The authors also quantified fragmentation by classifying forest patches into three categories, ranging from large and intact, to small and distant. Most forests (98%) were found to have minimal perforation or gaps, and a majority of India’s forest area (77%) was found to fall in the large and intact category. These results suggest that though fragmentation is on the rise, with proper management and mitigation, connectivity between forest patches in India can still be restored.

The authors recommend that the conservation of biodiversity be incorporated into infrastructure planning. In Central India, where forest patches were found to be larger but more isolated, the focus should be on restoring connectivity. In the Western Ghats, the large number of small patches indicates that further fragmentation should be avoided either by rerouting future roads, railways, and pipelines, or constructing mitigation measures. By using the spatial datasets resulting from this research, land-use planners can decide where and how future infrastructure should be built to minimize losses to biodiversity in India.


The spatial data from this study is available open access HERE.


Research Article: Bits and pieces: forest fragmentation by linear intrusions in India – Rajat Nayak, Krithi K. Karanth, Trishna Dutta, Ruth Defries, K. Ullas Karanth, Srinivas Vaidyanathan – Land Use Policy, 2020

Find the original research paper here.

Find the Kannada translation here.