Assam: New study reveals alarming decline in Guwahati’s forest cover

Guwahati: The city of Guwahati has seen a significant decline in its forested areas over the past four decades, according to a study using satellite imagery.

The study, which analyzed urban forest dynamics from 1976 to 2018, found that dense and moderately dense forests in the region decreased by 44% and 43%, respectively, while non-forest areas grew by 1,475 hectares over the same period.

“Dense forest patches are limited to only three – Hengrabari, Jalukbari and Amchang reserve forest possess dense forest patches of the eight reserved forests within GMA while the non-protected hills reported a significant 1309% increase of non-forest land use,” stated the study done by Chandra Kant Pawe of Geography department of Pragjyotish College and Anup Saikia of Geography Department, Gauhati University.

The study was published in Geografisk Tidsskrift-Danish Journal of Geography.

Since 1950, urban areas have seen unprecedented growth around the world. The United Nations (UN) estimates that by 2035, 2,363 metropolitan areas will be home to nearly 62.5% of the world’s urban population, with 1.8 billion people living in the Asia-Pacific region alone. Urbanization often leads to the expansion, alteration, and impact of urban land use on natural physical environments and ecosystem services. Urban forests, which consist of trees within urban limits, whether naturally grown or planted, provide a range of important ecological, economic, and social benefits. These benefits include maintaining biodiversity and improving the physical, mental, and social health of residents.

The city of Guwahati is home to a total of 12 hills, with 8 of them being protected and designated as reserve forests and the remaining 4 being non-protected forests. These protected forest lands are home to an array of biodiversity, including 332 species of terrestrial vertebrates such as 214 species of birds, 57 species of reptiles, 36 species of mammals, and 25 species of amphibians.

The Guwahati Metropolitan Area (GMA) was once a small town but was designated as the capital of Assam in 1972. Since then, the non-reserve forests in the region have been under increasing pressure from human activity, with little regulation in place to protect them. In recent decades, the population of the GMA has grown, and this has led to an increase in human activity in the reserve forests as well. This has become a major ecological and political issue, as the forests are facing loss and fragmentation. It is crucial to understand the patterns of forest loss and fragmentation that are occurring within the protected and non-protected hills of the GMA in order to address this issue and protect these valuable resources.

The post-1972 surge of growth in Guwahati was brought on by a massive influx of population from the neighbouring areas By 2018, the city already hosted more than a million persons. Since this analysis relies on the use of satellite images, 1976 was chosen as the start of the analysis period as this is when the earliest multispectral scanner system images for the city are available.

During the study period, the dense forest areas declined from 19.8% to 11% at an annual rate of 0.13 hectares. The area under moderate dense forests was reduced by half, while open forests exhibited a 17% decline. Scrub areas reported minimal losses. On the contrary, non-forest land increased from 2% (1.2 ha) to 25.5% (16 ha) between 1976 and 2018. During the period 1976-1989, all forest categories experienced a progressive decline in their percentage cover. These losses were offset by an increase in the non-forest class, which recorded a growth of about 140%.

“A majority of this non-forest expansion was observed in the neighbourhoods of the Dispur locality, essentially due to the establishment of the state capital at Dispur in 1972. Subsequently, between 1989 and 2002, the growth of non-forest land remained significantly high at 151%. As a result, most of the hills displayed the emergence of new patches of non-forest areas characterized as settlement units, roads, open spaces, cleared forests, and agricultural plots,” the study revealed.

Remarkably, since 1971, the compound annual growth rate (CAGR) of the population in Guwahati has consistently recorded above 4% growth. This surging population initially settled in the accessible plain areas around the city downtown before spreading into the adjacent hills. This resulted in the rapid development of non-forest lands inside the centrally located hills of the GMA, namely, the Hengrabari reserve forest, North Kalapahar reserve forest, Sarania reserve forest, and Khanapara reserve forest.

With little or no enforcement of any protective legislation to check on these eco-sensitive areas, the non-forest class continued to proliferate and expand into dense forest and moderately dense forest areas of the hills. In 2006, the Assam Hill Land and Ecological Sites (Protection and Management) Act was legislated by the state government. Although the law put some regulation on the diminishing forest cover, the pressure shifted to the visibly less significant open forest and scrub, which were reduced by 12% and 17%, respectively, between 2002 and 2018.”

“During the study period, the non-forest classes expanded exponentially by 1176% at the expense of different forest categories. Notably, both dense forest and moderate dense forests were reduced by 44% and 43%, respectively, and registered an aggregate areal loss of 997 hectares. “Thus, the forests in the hills of Guwahati exhibited a dire but predictable pattern of development: forest areas disappearing at the expense of non-forest areas consistently growing,” the study stated.

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