Forest Types and Area of Assam
Assam is one of the greenest states of India. Roughly a third of its land is under some form of forest or tree cover, and the variety of forests is remarkable. Within one state you can find dense evergreen rainforest, moist deciduous sal forest, semi-evergreen forest in the foothills, cool subtropical and montane forest in the hills, riverine forest along the Brahmaputra, and the wide grass plains of Kaziranga. This is why the forests of Assam are a favourite of examiners: the facts are specific, the region-wise pattern is easy to remember, and the same names - Hollong, Sal, Nameri and Karbi Anglong - keep coming back in question papers.
Why forests matter for Assam
Forests are the backbone of Assam's environment and economy. They hold the soil of the hills together and reduce the force of floods, recharge the groundwater, shelter the state's famous wildlife, and supply timber, bamboo, cane, fuelwood and many minor products. The tea and silk industries, the paper mills and thousands of rural households all depend, directly or indirectly, on what the forests produce. Forests also help regulate rainfall and keep the Brahmaputra and Barak valleys habitable, so their protection is not only an ecological issue but an economic and social one as well.
How the forests are classified
Geographers classify the forests of Assam chiefly by climate and altitude. The foothills and the floodplains are warm and very wet, so they carry tropical forests; the higher hills are cooler and carry subtropical and temperate forests. Botanists further separate moist deciduous forest, where trees shed their leaves in the dry season, from evergreen forest, where the canopy stays green all year. The main types found in Assam are the tropical wet evergreen forests, the tropical semi-evergreen forests, the tropical moist deciduous forests, the subtropical evergreen forests, the montane or temperate forests, the riverine forests and the alluvial grasslands.
The main forest types
The tropical wet evergreen forests grow in the areas of heaviest rainfall - the upper Brahmaputra valley, the Barak valley and the eastern hills. They are tall, dense and multi-layered, and they contain the state's most valuable timber trees. The tropical semi-evergreen forests appear in slightly drier pockets and in the foothills; the Nameri and Dibru-Saikhowa areas are good examples. The tropical moist deciduous forests cover large parts of the lower Brahmaputra valley and the Barak valley, and the sal tree is their best-known member. The subtropical evergreen forests and the montane forests clothe the hills of Karbi Anglong and Dima Hasao, where the Barail range and the surrounding highlands support cooler-climate species and abundant orchids.
Region-wise distribution
The pattern becomes simple once it is tied to the map. The upper Brahmaputra valley and the eastern districts have tropical wet evergreen forests, which is why the Hollong and other giant trees are found there. The lower Brahmaputra valley has tropical moist deciduous and semi-evergreen forests, with sal and mixed hardwood species. The hill districts of Karbi Anglong and Dima Hasao have subtropical evergreen and montane forests and hold the largest share of the state's forest cover. The Barak valley in the south has tropical wet evergreen and semi-evergreen forests, while the river banks of the Brahmaputra carry riverine or riparian forest and grassland.
Important trees and species
The single most famous tree of the Assam rainforest is the Hollong, Dipterocarpus macrocarpus. It is the tallest tree of the Assam rainforest and is also the state tree. Other well-known evergreen species are the Nahor, the Ajhar, the Mekang and the Nahar. In the moist deciduous forests of the lower valley the dominant timber tree is Sal, Shorea robusta, along with teak in places. The forests are equally rich in bamboo and cane; the two commonest bamboos are Muli (Melocanna) and Jati (Bambusa). Along the Brahmaputra, the floodplain grasslands known locally as khayer are as important as the forests, because they are the home of the rhinoceros, the wild buffalo and the swamp deer.
Forest area and forest cover
Assam's recorded forest area is about 26,000 to 27,000 square kilometres. According to the latest State of Forest Report, forest and tree cover together account for roughly 36 per cent of the state's geographical area, against about 35 per cent in earlier assessments. Karbi Anglong is the district with the highest forest cover as well as the largest forest division. The recent trend has been mixed: dense forest has slightly decreased while open forest has increased, which means the total green cover is being maintained but its quality is under pressure.
Reserved and protected forests
Not all forest land is the same in law. A reserved forest is an area notified under the forest law where all activities are prohibited unless specifically permitted, and it enjoys the highest degree of protection. A protected forest is also government forest land but with fewer restrictions, while unclassed forest is forest land not yet formally settled. Assam's national parks and sanctuaries - Kaziranga, Manas, Nameri, Dibru-Saikhowa, Pobitora, Chakrashila and others - are the best-protected parts of this network, and many of them are also tiger reserves or biosphere reserves.
Threats to the forests
The main causes of forest depletion in Assam are jhum (shifting) cultivation in the hills, illegal felling, encroachment on forest land, and floods and riverbank erosion. Forest fires, mining and quarrying, and the pressure of roads and settlements add to the damage. Because these causes work together, the solutions also have to work together: protecting reserved forests, settling rights fairly, encouraging settled cultivation, checking the timber trade and restoring degraded land.
How to prepare this topic
- Fix the four main types first: wet evergreen, semi-evergreen, moist deciduous and subtropical/montane.
- Attach each type to a place - upper valley and eastern hills for wet evergreen, lower valley for moist deciduous, Karbi Anglong and Dima Hasao for subtropical and montane, Barak valley for wet evergreen and semi-evergreen.
- Memorise the star trees: Hollong as the tallest and the state tree, Sal as the main moist-deciduous timber tree, and Muli and Jati as the common bamboos.
- Learn the figures: about 26,000 to 27,000 square kilometres of recorded forest and about 36 per cent forest and tree cover.
- Remember that Karbi Anglong leads both in forest cover and in forest division area.
Common exam traps
- Do not confuse forest cover with recorded forest area; the first is about 36 per cent of the geographical area, the second about 26,000 to 27,000 square kilometres.
- The Hollong is the tallest tree, but Sal is the main timber tree of the moist deciduous forests - the two are often swapped.
- Kaziranga's vegetation is tropical moist deciduous forest with alluvial grassland, not evergreen rainforest.
- The grasslands of the Brahmaputra floodplain are called khayer, and they matter for wildlife as much as the tree forests.
Frequently Asked Questions
What percentage of Assam is under forest?
According to the latest State of Forest Report, forest and tree cover together account for about 36 per cent of Assam's geographical area. The recorded forest area, which is a legal rather than a green-cover measure, is about 26,000 to 27,000 square kilometres. The two figures are often confused, but they answer different questions and should be remembered separately.
Which forest type covers the largest area in Assam?
The tropical wet evergreen forests and the tropical moist deciduous forests together cover the largest area. The wet evergreen forests dominate the upper Brahmaputra valley, the Barak valley and the eastern hills, while the moist deciduous forests dominate the lower Brahmaputra valley. Subtropical and montane forests are important but occupy a much smaller area in the hills of Karbi Anglong and Dima Hasao.
What is the tallest tree of Assam and what are the common bamboos?
The tallest tree of the Assam rainforest is the Hollong, Dipterocarpus macrocarpus, which is also the state tree. Among the common bamboos, the two most widespread are Muli (Melocanna) and Jati (Bambusa). Both bamboo and cane are major forest products, and along with timber and fuelwood they support the rural economy of the state.
Which district has the highest forest cover in Assam?
Karbi Anglong has the highest forest cover in Assam, and it also has one of the largest forest divisions in the state. Dima Hasao follows with a high proportion of forest land. The two hill districts together account for a very large share of the state's total forest area because of their rugged terrain, low population density and extensive reserved forests.
What are the main threats to the forests of Assam?
The main threats are jhum or shifting cultivation in the hills, illegal felling, encroachment on forest land, and floods and riverbank erosion. Forest fires, mining and quarrying, and the spread of roads and settlements add to the pressure. Because the causes are linked, conservation in Assam works on several fronts at once - protecting reserved forests, settling rights fairly and restoring degraded land.