Northern Triangle temperate forests

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Stem of Alnus Nepalensis (By Krish Dulal (Own work) [CC-BY-SA-3.0 (], via Wikimedia Commons)


The Northern Triangle Temperate Forests ecoregion lies in the extreme northern area of the Golden Triangle of Myanmar. The region is scientifically unexplored, and the biological information, especially of its flora, is still based on the early, pioneering exploration done by Kingdon-Ward. There have been no detailed scientific surveys in this area since then, and current assessments of its biodiversity probably are underestimated. In all probability this ecoregion harbors many more species than are now attributed to it. Satellite imagery indicates that the ecoregion is still largely clothed in intact forests and presents a rare opportunity to conserve large landscapes that will support the ecological processes and the biodiversity within this eastern Himalayan ecosystem.

Location and General Description

caption WWF

The mountains originated more than 40 million years ago, when the collision between the drifting Deccan Plateau and the northern Laurasian mainland created the Himalayan Mountains, including these mountains in the Golden Triangle. Therefore, the mountains are young and unweathered; the terrain is rugged and dissected, with north-south-oriented ranges that reach south, toward the central plains of Myanmar. The peaks along this range rise steeply to attain heights of more than 3,000 meters. The Chindwin, Mali Hka, and N'mai Hka rivers originate in these mountains and flow south to converge in the lower reaches to form the Irrawaddy River.

Biogeographically, the mountains are an ecotone of the Assam-Indian, Eastern Himalayan, Indo-Malayan, and Chinese floras. Gondwana-era relicts that rafted north on the Deccan Plateau have also taken refuge here. Therefore, floristically, the ecoregion is extremely diverse. And the complex topography and moist conditions produced by the southwestern monsoon funneled in from the Bay of Bengal have provided the localized climatic variations that promote endemism.

Floristically, the ecoregion is very similar to the middle mountain forests of the Eastern Himalaya. The temperate forests lie between 1,830 and 2,700 meters. At lower elevations the forest transitions into the subtropical forests and, in the upper elevations, into the sub-alpine conifer forests. The temperate forests are characterized by Alnus nepalensis, Betula cylindrostachya, Castanopsis spp., Schima spp., Callophylus spp., Michelia spp., and Bucklandia populnea. Rich epiphytic rhododendron shrub vegetation is common. At higher elevations rhododendrons, especially Rhododendron decorum, R. magnificum, R. bullatum, R. crinitum, and R. neriiflorum become a dominant component in the vegetation.

At elevations above 2,100 meters, the broadleaf forests transition into a mixed forest, where species of Quercus, Magnolia, Acer, Prunus, Ilex, and Rhododendron are mixed with Picea brachytyla, Tsuga dumosa, Larix griffithiana, and Taiwania flousiana. The rich, diverse shrub flora persists here but is characterized by species of Acer, Berberis, Clethra, Enkianthus, Euonymus, Hydrangea, Photinia, Rhododendron, Rubus, Betula, and Sorbus.

Biodiversity Features

Ninety-one mammal species are known from this ecoregion, but additional surveys may well reveal the presence of additional species. But for now the only ecoregional endemic mammal attributed to the Northern Triangle Temperate Forests is the Gongshan muntjac (Muntiacus gongshanensis) (Table 1). However, there are several other threatened species in the ecoregion's assemblage that deserve conservation attention, namely the tiger (Panthera tigris), takin (Budorcas taxicolor), clouded leopard (Pardofelis nebulosa), red panda (Ailurus fulgens), wild dog (Cuon alpinus), Asiatic black bear (Ursus thibetanus), stump-tailed macaque (Macaca arctoides), capped leaf monkey (Semnopithecus pileatus), red goral (Naemorhedus baileyi), great Indian civet (Viverra zibetha), back-striped weasel (Mustela strigidorsa), Irrawaddy squirrel (Callosciurus pygerythrus), and particolored squirrel (Hylopetes alboniger).

Table 1. Endemic and Near-Endemic Mammal Species.
Family Species
Cervidae Muntiacus gongshanensis
An asterisk signifies that the species' range is limited to this ecoregion.


Of the 365 birds known from this ecoregion, the rusty-bellied shortwing (Brachypteryx hyperythra) is the only ecoregional endemic (Table 2). But there are several species that need mature habitats, have low tolerances for disturbances that are indicators of habitat integrity, and deserve conservation attention. These species include the Oriental pied-hornbill (Anthracoceros albirostris), wreathed hornbill (Aceros undulatus), Blyth's tragopan (Tragopan blythii), Himalayan flameback (Dinopium shorii), and Sclater's monal (Lophophorus sclateri). The ecoregion also overlaps with the Eastern Himalayas Endemic Bird Area (130), which contains seven restricted-range species.

Table 2. Endemic and Near-Endemic Bird Species.
Family Common Name Species
Turdidae Rusty-bellied shortwing Brachypteryx hyperythra
An asterisk signifies that the species' range is limited to this ecoregion.


But the conservation priority of this ecoregion goes beyond the species lists. A critical component of the Himalayan ecosystems is the dependence of ecological processes-from seasonal bird and mammal migrations to watershed protection-on altitudinal connectivity and the intactness of ecosystems that are stratified by elevation. Loss of habitat or even large-scale degradation can have far-reaching consequences. Birds that migrate up and down the steep slopes will lose staging and feeding habitat, thus disrupting their migrations. Loss of ground cover in the high elevations can result in erosion on steep slopes, with the consequences being manifested as floods and silting far away, in lowland plains and mangroves in the river deltas.

Current Status

Because of the remoteness and inaccessibility of this high-elevation ecoregion that sits on steep, rugged mountains, most of the habitat in this ecoregion is still intact. However, it receives no formal protection.

Types and Severity of Threats

Throughout Myanmar, the hill tribes who still practice shifting cultivation are being pushed further and further into marginal, steeper lands for a variety of reasons, including logging in the lower elevations that were the traditional agricultural areas. The consequent clearing of new forests for shifting cultivation and poppy cultivation will result in severe erosion and loss of habitat and biological diversity.

Justification of Ecoregion Delineation

In a previous analysis of conservation units across the Indo-Malayan region, MacKinnon identified a subunit (09b) that includes the tropical and subtropical moist broadleaf forests in the Kachin and upper Chindwin areas of northern Myanmar. In keeping with our rules for defining ecoregions, we represented the temperate broadleaf forests in this subunit with the Northern Triangle Temperate Forests.

Additional Information on this Ecoregion

Further Reading

  • Kingdon-Ward, F. 1921. In farthest Burma; the record of an arduous journey of exploration and research through the unknown frontier territory of Burma and Tibet. Philadelphia:Lippincott.
  • Kingdon-Ward, F. 1952. Plant hunter in Manipur. London: Cape. 254 pp.
  • World Wide Fund for Nature (WWF) and The World Conservation Union (IUCN) 1995. Centres of Plant Diversity: A Guide and Strategy for Their Conservation. Volume 2: Asia, Australasia and the Pacific. Cambridge: IUCN. ISBN: 2831701988
  • Lwin, T. U. 1995. Biodiversity conservation and management in Myanmar. Pp259-326. In: Banking on biodiversity. Report on the regional consultation on biodiversity assessment in the Hindu Kush-Himalayas. International Centre for Integrated Mountain Development (ICIMOD). Nepal. ISBN: 9291155640
  • Blower, J. n.d. Species Conservation Priorities in Burma. UNDP/FAO Nature Conservation and National Parks Project, Burma.
  • Stattersfield, A. J., M. J. Corsby, A. J. Long, and D. C. Wege. 1998. Global Directory of endemic bird areas. Cambridge, UK: Birdlife International. ISBN: 1560985747
  • MacKinnon, J. 1997. Protected areas systems review of the Indo-Malayan realm. Canterbury, UK: The Asian Bureau for Conservation (ABC) and The World Conservation Monitoring Center (WCMC)/ World Bank Publication. ISBN: 2880326095



Disclaimer: This article is taken wholly from, or contains information that was originally published by, the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.






Fund, W. (2014). Northern Triangle temperate forests. Retrieved from


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