Satellite study shows severe forest loss in Assam due to encroachment, agriculture

Guwahati, Dec 10: Forest ecosystems in Assam are increasingly threatened by anthropogenic activities, leading to significant forest degradation despite being granted protection by legislation, a satellite-imagery-based study has revealed.

The study, carried out in the reserve forests of North Bank, observed that agricultural lands and open forests increased rapidly, besides settlements, while dense forests decreased, and noted that similar cases of encroachment across other reserved forests in Assam have also emerged in the recent decade.

The study was carried out by a team of researchers of Raha College, Gauhati University and Dimoria College in Behali Wildlife Sanctuary, Biswanath, Gohpur, Naduar and Singlijan Reserved Forests using object-based image analysis over 30 years (1990–2020). Landsat 5 and Landsat 8 satellite imagery were used and these datasets were downloaded from USGS Earth Explorer.

The findings highlighted a conspicuous decline in the dense forest class of Behali Wildlife Sanctuary, Gohpur Reserved Forest, Biswanath Reserved Forest and Naduar Reserved Forest, while only Singlijan Reserved Forest recorded an increase in its dense forest class by 1.54 per cent.

The most noticeable decline in dense forest was observed in Biswanath Reserved Forest whereby 65.92 per cent dense forest was lost during the 30 years.

Similar loss in dense forest cover was also observed in Gohpur Reserved Forest (28.6 per cent) followed by Naduar Reserved Forest (27.02 per cent) and Behali Wildlife Sanctuary (16.98 per cent).

Although the loss of dense forest in Biswanath Reserved Forest was more pronounced, it also gained an increase of 40 per cent in open forest class during the study period.

However, the same cannot be said of the Gohpur Reserved Forest, which witnessed severe forest degradation.

Interestingly, 60.28 sq km of the Gohpur Reserved Forest emerged as agricultural land in 2020, while 34.13 sq km of barren land in 1990 was completely lost in 2020.

“The reserve forest boundary was heavily compromised as settlements and agricultural land fully engulfed it,” the study noted.

At Naduar RF, 6.2 sq km of barren land class in 1990 had completely disappeared by 2020, while settlement and agriculture land class cropped up in 2.72 sq km and 12.7 sq km in 2020, respectively.

Even inside Behali Wildlife Sanctuary, agricultural land emerged as a new category in 2020, occupying 19.5 sq km of the total 146 sq km accounting for 13 per cent of the study area. Settlements also appeared as a new category, with an area of 1.05 sq km.

“The expansion of agricultural land in Sonitpur East Forest Division is alarming, as it reflects increasing anthropogenic pressure that potentially contributes to habitat fragmentation and biodiversity loss,” the researchers pointed out.

The researchers concluded that the communities residing near the fringe areas of the protected forests are mostly from poor and backward communities, highly dependent on using forest products for their sustenance and survival, exerting heavy biotic pressure on the regenerative capacity of the forests.

“Additionally, as part of socio-cultural practices of the local communities, grazing by live-stock and plantation of exotic species in the southern boundary of the forest division have aided in the further degradation of forests,” the study observed.

The study cautioning that encroachment of forests can disrupt wildlife corridors, increase human-animal conflicts and exacerbate the pressure on the remaining forest fragments.

The study by Sujata Medhi, Kunal Chanda, Sourav Chetia, Anup Saikia and Ashok Kumar Bora has been published in the Australian Geographer.