A New Study Analyses Forest Connectivity in India

While tree cover is often used as an indicator of a country’s greenery, focusing solely on this metric can be misleading. Calculating tree cover may exclude fragmented forests, which are not ideal ecosystems.

Forest connectivity is crucial because it allows wildlife to move freely, enabling species to find food, mates, and suitable habitats, which supports healthy populations and genetic diversity.

Connected forests also help maintain crucial ecological processes such as seed dispersal, pollination, and predator-prey relationships, making forest ecosystems more resilient to threats like disease, climate change, and habitat loss.

In contrast, fragmented forests, where habitats are isolated by roads, agriculture, or development, often result in small, vulnerable populations, reduced genetic diversity, and higher risks of extinction.

Fragmentation can also disrupt ecosystem services, like clean water and air regulation, ultimately reducing the overall health and productivity of the landscape.

While the Forest Survey of India (FSI) and other independent studies regularly report on India’s gross forest cover, so far, there has been no systematic framework to understand structural connectivity and monitor forest fragmentation across the country.

In a study published in July 2025, Prof. RAAJ Ramsankaran of IIT Bombay and his collaborators, Dr. Vasu Sathyakumar and Mr. Sridharan Gowtham of SASTRA Deemed University in Tamil Nadu, have proposed a framework that uses remote sensing data and open-source digital tools to map forest connectivity at both the state and national levels.

In addition to providing insights into how connected the forests are, the framework can also be used to analyse the impact of afforestation efforts, determine the resilience of different forest types to deforestation, and identify the states undergoing severe changes in forest cover.

A key aspect of this approach is its classification of forest landscapes into seven types, each with distinct ecological implications:

Cores, which are relatively large and intact forest habitats
Bridges, which connect different cores
Loops, which connect parts of the same core
Branches, which are narrow extensions from cores
Perforations, which are non-forest clearings within cores
Edges, which form the outer boundary of cores
Islets are small, isolated forest patches

The study finds that cores are the most resilient to deforestation, while islets are the most vulnerable, often undergoing further fragmentation or loss within a short period. In this sense, afforestation activities that primarily result in the creation of islets may not meaningfully contribute to forest health or connectivity.

The study adds that India’s afforestation programmes should focus on strengthening existing cores and building bridges between them, which could potentially yield better-connected, more resilient, and ecologically sustainable forests.

The framework also has the potential to inform infrastructure planning by helping identify areas where connectivity is most at risk, thus supporting more scientifically informed decisions and reducing ecological disruption.

Urban Forests

As part of the study, the researchers applied the analysis to digital forest cover maps of India for the years 2015 to 2019, obtained from the Copernicus Global Land Service (CGLS) Land Cover Map.

CGLS provides global land and forest cover information at various resolutions.

Unlike most previous studies on forest cover, which report only net gains or losses, this study mapped forest loss and gain separately.

The results show that from 2015 to 2019, all states in India experienced a net loss in forest cover. Overall, India lost 18 square kilometres of forest for every 1 square kilometre gained.

Nearly half of the 56.3 sq. km. of gross forest gain occurred in Andhra Pradesh, Tamil Nadu, Karnataka, and Rajasthan, while Tamil Nadu and West Bengal together accounted for almost half of the 1,032.89 sq. km. of gross forest loss.

More significantly, over half of the newly added forest covers are islets, which do not substantially improve structural forest connectivity. This suggests that even where forest cover is increasing on paper, the ecological value and resilience of those forests may be limited.

It is interesting that the State of Forest Report 2023, prepared by the Forest Survey of India (FSI), shows an increase of 1,445 sq km in forest and tree cover in the country, as compared to the assessment made in 2021.

While the findings from this latest study appear to differ from those of FSI, which indicate an overall increase in forest cover, the results from FSI and this study are not directly comparable.

FSI uses different criteria from the CGLS to identify forests and does not distinguish between fragmented and continuous forests. FSI defines forested areas as those with a minimum of 10% tree canopy cover and relies on satellite imagery with a 23.5 m resolution.

In contrast, the CGLS dataset used in this study applies a 15% canopy threshold and a 100 m resolution. The researchers also had to rely on the internationally accepted CGLS dataset, as FSI data are not publicly available for similar analyses.

One limitation of the current study is that at 100 m resolution, narrow linear features such as roads and railways may not be fully detected, and forest fragments smaller than 100 m may be missed.

However, the strength of the framework lies in its scalability, cost-effectiveness, and use of open-source tools. It can be expected to give consistent results with similar datasets at finer resolutions and can be applied at different spatial and temporal scales.

Simply measuring tree cover without considering forest connectivity provides an incomplete and sometimes false picture of a landscape’s health, ecological value, and sustainability.

Therefore, this study can serve as a valuable tool for long-term forest monitoring, planning and informed infrastructure development in and around forested areas, both in India and in similar contexts globally.