Forests in Nepal

25.4% of Nepal's land area, or about 36,360 km² (14,039 mi²) is covered with forest according to FAO figures from 2005. FAO estimates that around 9.6% of Nepal's forest cover consists of "primary forest" which is relatively intact. About 12.1% Nepal's forest is classified as "protected" while about 21.4% is "conserved" according to FAO. About 5.1% Nepal's forests are classified as "production forest." Between 2000-2005, Nepal lost about 2640 km² of forest. Nepal's 2000-2005 total deforestation rate was about 1.4% per year meaning it lost an average of 530 km² of forest annually. Nepal's total deforestation rate from 1990-2000 was 920 km² or 2.1% per year. The 2000-2005 true deforestation rate in Nepal, defined as the loss of primary forest, is -0.4% or 70 km² per year.

Types:

Broadleaved forests

Sal forests, corresponding to the north Indian moist deciduous forest classification of Champion and Seth (1968), consist of forest stands where sal (Shorea robusta) is the predominant species (50 percent or more of the total basal area). The best stands grow on moist, well-drained, deep sandy loam soils with good subsoil drainage. On good sites, sal may reach 45 m, but it generally ranges between 25 and 40 m. It is considered a climax (climatic, edaphic or bioedaphic) formation and constitutes one of the most important forest types of Nepal, occurring in the northern Terai and valleys of the Churia hills. The type extends up to about 1 000 m in the Churia hills and in the mountains where it meets with the subtropical pine forests. Due to its resistance to fire, its coppicing ability and its adaptability to various soil and site conditions, it continues to retain its hold as a major species despite human influence. Sal is much used in Nepal, chiefly for construction. Common associates include asna (Terminalia tomentosa), jamun (Syzygium cuminii), banjhi (Anogeissus latifolia) and botdhainro (Lagerstroemia spp.). On higher reaches chir pine (Pinus roxburghii) is a common associate.

The Terai hardwood forests are mixed broadleaved stands growing in the Terai that may or may not contain sal. Other commercial timber species such as asna, jamun, botdhainro, karma or haldu (Adina cordifolia), gutel (Trewia nudiflora) and semal (Bombax ceiba) singly, or in combination, have a greater basal area than sal. They are closed forests of good height and development with a lower storey of smaller trees and shrubby undergrowth. Several subgroups in which one species achieves dominance are represented in this type. Asna stands are among the most important subtypes and corresponds to the edaphic variant of the "moist deciduous forests" type of Champion and Seth. These broadleaved forests occur throughout the Terai and valleys of the Churia hills where soil is heavy, moisture retentive or wet and on clayey patches. Asna is used as a construction timber. Banjhi stands form another important subtype and are almost pure in the western Terai where they occupy drier sites. These stands are generally well stocked, but the trees are of small size.

The khair-sissoo forests, corresponding to the general seral types of "Tropical dry deciduous forests" of Champion and Seth occur as the first coloniser on new sandy or gravelly alluvium along large rivers in the Terai. Sissoo (Dalbergia sissoo) generally predominates. Although this type occurs throughout the Terai, it occupies significant areas only in the Biratnagar, Banke, Bardia and Kanchanpur divisions. The stand canopy is light but usually fairly complete with 18- to 25-m-high trees. Khair (Acacia catechu) is usually present but often inconspicuous in the mixture. It may sometimes occur in pure stands. The older forests have a more or less definite understorey composed of young trees that will replace the khair-sissoo forests as succession takes place. Tamarix dioica, Calotropis procera and Holoptelea integrifolia are often present.

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The lower slope mixed hardwoods occur in the eastern and central Himalayas in moist localities between 650 m and 1 500 m. In western Nepal the type is represented in moist hollows and depressions between 1 000 and 2 000 m elevation. These forests correspond to the type "northern montane subtropical forests" of Champion and Seth. They are characterised by the prevalence of chestnuts (Castanopsis sp.) and chilaune (Schima wallichii), which are almost always present, and also Quercus. Shorea robusta may be found but its presence is usually ascribable to edaphic peculiarities of the site. Pines are absent or confined to drier, sandy soils or well-drained ridges. The forests are of good height and stocking. The dominant species are mostly evergreens although some large, briefly deciduous trees occur, sometimes in pure consociations such as Betula. The tree canopy reaches a height of 20 to 35 m under normal conditions. A middle storey of evergreen trees can generally be found.Oak forests of Nepal are found in the Mahabharat range, extending up into the subalpine region. These forests correspond to "northern montane wet temperate forests" and "Himalayan moist temperate forests" of Champion and Seth.The wet forests are closed evergreen high forests of large girth but medium height, rarely exceeding 25 m. The type occurs from 1 800 to 3 000 m, mostly in eastern Nepal where rainfall is more than 2 000 mm. Deciduous species occur, particularly at the higher altitudes, but they form a relatively small proportion of the stand. Although the type is essentially a mixed one there is a marked tendency for a few species to predominate, such as oaks and Lauraceae species. Quercus lamellosa, Q. pachyphylla, Castanopsis tribuloides, Acer campbellii, Machilus spp. and Michelia spp. are the most common species.The moist type consists of three common oaks providing a simple and convenient basis for subdivision into three elevation zones, each with its typical coniferous counterpart. Ban oak (Quercus incana) occupies the lowest belt of the temperate zone, particularly in the outer ranges and southern aspects. The intermediate zone is occupied by moru oak (Quercus dilatata) whereas kharsoo oak (Quercus semecarpifolia) characterises the highest temperate belt.The upland mixed hardwoods correspond to "lower and upper western Himalayan temperate forests" of Champion and Seth. They are deciduous forests 20 to 30 m high. Trees can reach large diameters, but are usually branchy. The species occur mixed, singly or in groups of varying extent. The type is commonly found from 1 800 to 3 000 m in moist hollows and depressions, often as strips along the streams or on the gentler slopes. In western Nepal, typical species and genera are Aesculus indica, Juglans regia, Alnus nepalensis, Acer, Cornus, Corylus, etc.