The Dichu Reserve Forest lies in the northeastern part of Lohit district of Arunachal Pradesh, and covers an area of 179,200 ha. This is the easternmost part of India (Arunachal Pradesh), forming a tri-junction with Tibet and Myanmar. The area is well recognized as the gateway for plant and animal migration between India-Tibet, India-Myanmar and the Malayan region. The vast stretch of Dichu forest is practically undisturbed and has been preserved intact for ages. Species diversity is at its best in this forest (Haridasan et al. 1999). The Dichu Valley runs roughly east-west, flanked on both sides by high rise peaks with steep slopes. The northern ridges are part of the McMahon line. Along the course of the Dichu river valley, where it joins the Lohit river (Negichu) in the west, there is a gradual ascent towards its source in Myanmar. In the Indian territory, eight rivulets drain into Dichu on the northern side, whereas on the southern side seven nullahs or rivulets drain into the Dichu river. These are perennial, snow-fed rivers, turbulent and difficult to navigate in many places. However, in flat areas, the flow is gentle. The Dichu river, after flowing for about 50 km westward, drains into Negichu river, after which it is known as the Lohit. The river continues to flow southward. Except for a narrow belt near Dichu, beyond Kahao, where the land appears somewhat plain and plateau-like, the river course has steep slopes and high peaks. Near Jachup, the valley is very wide, and like a meadow. The hills are clothed by dense vegetation of varying types of broadleaf and coniferous species. It is interesting to see large sheets of snow in the higher reaches of the meandering river. The climate of the area is cool temperate type, though the areas near Kahao are slightly warmer than Hotspring and Jachup, where conditions are chilly. The maximum temperature in summer often goes up to 32 °C and the minimum falls below freezing point in winter. Due to the lack of infrastructure, there is no meteorological observatory in this place. The nearest data collection station is at Walong. The climate changes drastically towards more wet conditions from Melinja. Areas beyond Melinja experience heavy snowfall during winter. In the reserve forest, there is very little human habitation. The circle headquarters Kibithoo is the nearest administrative centre. The inhabitants in the nearby villages are of Buddhist and Mishmi origin. Besides the original inhabitants, a population worth mentioning is that of Nepali labourers. The local people in Kahao village practice a more settled agriculture, using terrace cultivation with well-developed irrigation. Some villagers of the Mishmi tribe go on week-long hunting trips to these interior hills for meat, hide, skulls and other trophies. They also collect wild medicinal plants (Haridasan et al. 1999). Dichu has one of the last remaining extensive forest covers in India. Haridasan et al. (1999) identified seven forest types in this areas: Pine Forest, Eastern Himalayan Moist Temperate Forest, Temperate Broadleaf Forest, Temperate Coniferous, Mixed Coniferous Forest, Alpine Forest and grassland.
AVIFAUNA: A total of 266 bird species have been recorded so far (Hazarika 2003). Among them, the record of Elliot’s Laughingthrush Garrulax elliotii near Hotspring (3,200 m) on September 15, 1994 is noteworthy (Singh 1994). This appears to be the first record of the species for the Indian subcontinent.
This site covers three biomes: Biome-5 (Eurasian High Montane- Alpine and Tibetan); Biome-7 (Sino-Himalayan Temperate Forest); and Biome-8 (Sino-Himalayan Subtropical Forest). These biome types have their corresponding bird species. For example, BirdLife International (undated) has identified 48 species in Biome-5. Hazarika (2003) has listed 10 species from this biome. In Biome-7, Birdlife International has listed 112 species, of which 74 species are found at this site. Similarly, in Biome-8, of the 95 species listed by BirdLife International, 59 have been seen here. This proves that the site is a very good representative of the extant natural forest of northeast India.
Besides the biome species, many globally threatened and Restricted Range species are also present here. The area is included in the Himalaya Endemic Bird Area (Stattersfield et al. 1998).
Hazarika (2003) claims to have seen two groups of Himalayan Monal Lophophorus impejanus near a place called Mesai. According to Ali and Ripley (1987) this pheasant is replaced in the eastern Himalayas by Sclater’s Monal Lophophorus sclateri. However, Singh (1994) has recorded it from two sites in Arunachal Pradesh: Mago in the western portion and Malinye in east Arunachal. Malinye is not very far from Mesai.
Another bird of interest is the Pale-capped or Purple Wood-Pigeon Columba punicea, of which two flocks were seen in southern Dichu (Hazarika 2003).
Till now five species of pheasants have been reported from this site: Kaleej Lophura leucomelanos, Tibetan Eared-pheasant Crossoptilon harmani, Himalayan Monal Lophophorus impejanus, Blood Pheasant Ithaginis cruentus and Grey Peacock-pheasant Polyplectron bicalcaratum.
OTHER KEY FAUNA: Due to its inaccessibility, the forest is well preserved, and is a true representation of climax type of vegetation. This is the abode of temperate zone mammals such as Red Panda Ailurus fulgens, Asiatic Black Bear Ursusthibetanus, Goral Nemorhaedus goral, Serow Nemorhaedussumatraensis, Musk Deer Moschuschrysogaster and Takin Budorcas taxicolor. Other important species recorded in the area are Barking Deer Muntiacusmuntjak and Leopard Pantherapardus. Snow Leopard Uncia uncia is reported at Melinja, at about 2,000 m (Haridasan et al. 1999), but this needs confirmation.
Pressure/threats to key biodiversity
MAIN THREATS: Collection of medicinal plants and other Non Timber Forest Produce; Poaching of animals; Slash and burn agriculture in southern Dichu Valley.
The Dichu Valley is rich in natural resources. Some of them are harvested for immediate returns, while others are wild precursors of economically important cultivated plants that could provide a wide gene pool for the improvement of cultivated or crossbred varieties. There is no significant human habitation within the reserved forest. The local people visit the forest particularly for hunting, from the west and south.
Key contributors: Asif Hazarika, K. Haridasan, Pratap Singh and Asham Borang.
BirdLife International (2023) Important Bird Areas factsheet: Dichu Reserve Forest. Downloaded from
http://www.birdlife.org on 09/02/2023.