vegetation types and habitats of nepal
The monsoonal climate and huge altitudinal range found in Nepal creates a wide array of habitats, from the lowland evergreen tropical forests in the Terai (below 200m), through warm temperate evergreen, cool temperate deciduous forests and then coniferous forest to the tree line. Above this Rhododendron scrubland extends up to the high alpine meadows before plant life gives way to the frozen wastes of the barren snow capped peaks of the world’s highest mountains (the highest recorded flowering plants are found at around 6100 m). The deep river valleys create their own microclimates, and dramatic changes in the vegetation can be seen in relatively small areas with differing aspect and altitude.
Schweinfurth (1957) produced the first vegetation map of the entire himalaya, and laid the foundations for more detailed work in Nepal by later authors. Stearn (1960) proposed a broad catagorisation of Nepal into three geographic regions: Western Nepal (west of the Karnali River, ca. longitude 83°E), dominated by a western Himalayan flora; Eastern Nepal (east of the Koshi River, ca. 86°30'E), dominated by an eastern Himalayan flora; and Central Nepal (between 83° and 86°30'E), comprising a mixing zone of these two floras. This did not distinguish any altitudinal differences, but was used as the basis for the first comprehensive checklist of the plants of Nepal (Enumeration of the Flowering Plants of Nepal, Hara et al., 1978 et seq.). In contrast zoologists Swan and Leviton (1962) used a system of seven ecological zones based on altitude, but did not differentiate any east-west patterns.
Two landmark publicatons appeared in 1972, both the result of many years of fieldwork by the authors, combined climatic and phytogeographic regions. These two systems of vegetation classification (Stainton, 1972 and Dobremez, 1972) are widely used today and are outlined below. Other notable contributions to plant ecology and vegetation studies in Nepal have been made by George Meihe (and co workers, 1990 onwards) and Shakya et al. (1997). It should be noted that in all these systems generalisations need to be made as vegetation zones are greatly affected by local conditions, particularly rainfall and aspect. Sometimes the boundaries are abrupt and clear, but often they are gradual and intergrade over quite large areas. The vegetation pattern for the whole country is a complex mosaic and the categorisation is still open to debate.
stainton classification [top]
Adam Stainton (1972) used the following eight climatic and phytogeographic regions in his classification of forest types of Nepal:
Stainton recognised 35 forest types classified into ten major groups which have been widely adopted in later works. A detailed account of this classification is in preparation, the major groups are:
Plantation: a number of districts in the Terai have substantial plantations of Dalbergia sissoo, Eucalyptus spp. and Tectona grandis (Teak), particularly in Sagarnath and Nepalgunj. Plantations in the Mid-Hills comprise Pinus roxburgii, Pinus wallichiana, Pinus patula and Alnus nepalensis.
Tropical moist lowland Indo-Malayan forest (below 1000 m [to 1200 m in Churia hills]): predominantly Sal (Shorea robusta). Acacia catechu and Dalbergia sissoo replace Sal in riverine forests. Other riverine forest types include evergreen species such as Michelia champaca, or deciduous species such as Bombax ceiba. In the foothills of western Nepal Sal forest is replaced by Terminalia/Anogeissus forest.
Subtropical broad-leaved evergreen forest (1000-2000 m): central and eastern parts have Schima wallichii/Castanopsis indica forest. Riverine forest of Toona(Cedrela) and Albizia occur low down along the valley sides of large rivers (e.g. Arun Khola). Alnus nepalensis is widespread along streams and moist places.
Subtropical pine forest (1000-2200m): South facing slopes of the Siwalik and Mid-Hills in western and central regions, dominated by Chir Pine (Pinus roxburghii).
Lower temperate broad-leaved forest (2000-2700m in the west; 1700-2400 in the east): Mid-Hill forests with Alnus nitida, Castanopsis tribuloides, Castanopsis hystrix, Lithocarpus pachyphylla, Quercus spp. Alnus nitida forest is confined to the river banks of the Mugu Karnali (2130-2440m). In west Nepal Quercus leucotrichophora and Quercus lanuginosa forests and Quercus floribunda. Central and eastern parts have Quercus lamellosa forest. Lithocarpus pachyphylla forest occurs in the east.
Lower temperate mixed broad-leaved forest (1700-2200): generally confined to the moister north and west-facing slopes, with several tree species of Lauraceae prominent.
Upper temperate broad-leaved forest (2200-3000m): drier south-facing slopes of central and eastern parts have Quercus semecarpefolia forest, but this is absent in higher rainfall areas such as the Upper Arun and Tamur valleys and hills to the north of Pokhara.
Upper temperate mixed broad-leaved forest (2500-3500m): mostly found in central and eastern regions, mainly on the moister north- and west-facing slopes. Acer and Rhododendron species predominate. In the west can be found forests of Aesculus/Juglans/Acer.
Temperate coniferous forest (2000-3000m): Pinus wallichiana is an aggressive coloniser and can be found throughout Nepal at these elevations, extending up to 3700m. In the west, Cedrus deodara, Picea smithiana, Juniperus indica and Abies pindrow forests occur. The upper Bheri River valley marks the easternmost extent to Cedrus deodara. In Nepal, Larix himalaica forest only occurs in the Langtang and Buri Gandaki valleys, and favours glacial moraine habitats. Larix griffithiana, the eastern Himalayan larch, extends up to 3940m. Cupressus torulosa forest and Tsuga dumosa forest are widespread throughout Nepal between 2130-3340m.
Subalpine forest (3000-4100m): Abies spectabilis, Betula utilis, Rhododendron spp.
Above the tree line Stainton's forest/vegetation types can readily be extended to include: [top]
Alpine scrub (above 4100m): varied associations with Juniperus spp. and Rhododendron spp. Juniperus recurva, Juniperus indica, Juniperus communis, Rhododendron anthopogon, Rhododendron lepidotum, Ephedra gerardiana and Hippophae tibetana in the inner valleys. North of the Dhaulagiri-Annapurna massif Caragana versicolor, Lonicera spinosa, Rosa sericea and Sophora moorcroftiana occurs. Alpine meadows (Kharkas) are grazed during the summer and rainy seasons.
Perpetual snow (above 5200m): Stellaria decumbens and Parrya lanuginosa have been recorded at 6100m, but beyond this point in the Arctic desert/Nival zone, even mosses do not survive.
dobremez classification [top]
Jean-François Dobremez (1972, 1976) recognised 4 belts (western; northwestern; central; eastern); 11 bioclimatic zones, 35 forest types, 75 vegetation types, 118 ecosystems. These are used in the conservation literature in Nepal (e.g. Biodiversity Profiles Project). A detailed account of the Dobremez classification is in preparation [see also Laboratoire d'Ecologie Alpine website].