The Kingdom of Bhutan is a mountainous country of about 40 077 km2 situated in the eastern part of the Himalayan range between the Tibetan plateau in the north and the Indian plain in the south. To get a better understanding of the land-use pattern and the conditions for forestry as well as other land uses in Bhutan, one has to keep in mind the way the Himalayan range was erected. More than 10 million years ago, during the Tertiary Period, tectonic movements pressed the Indian plat in the south against the Asian continent in the north. The high mountain ranges aligned north-south, hampered active exchange between the main social and production areas located in the main valleys until these areas were connected by the national highway established in the late 1960s.
Photo 1. Major settlements are located in the main valleys: Dzongkhag of Tongsa
This east-west oriented national highway of about 600 km complemented by feeder roads opening up the north-south aligned valleys, links the administrative units, called Dzongkhags, with the capital Thimphu. Along its route the highway climbs several times to elevations of over 3 000 m when crossing passes and comes down to about 400 m when reaching the bottom of the steep V-shaped valleys where rivers drain the catchment areas in the north to the plain in the south.
The change in altitude from the high elevations in the north to the plains in the south is even more impressive. The altitude declines from about 7 500 m to about 200 m above sea level within a distance of less than 175 km (MoA, 1997), which gives a general idea of the topography of Bhutan. The distribution of altitude zones as percentage of the total area of Bhutan is given in Table 1. However, a few broad U-shaped glacial valleys can be found in the eastern and central part of the country with more favourable conditions for agricultural land use.
Table 1. Altitude zones and potential natural vegetation of Bhutan
|Altitude zones||Area(ha)||Area(%)||Vegetation zones|
|>3600 m||1 258 418||31.4||alpine tundra/cold temperate forest|
|3000–3600 m||529 016||13.2||cold temperate forest|
|2400–3000 m||573 101||14.3||warm temperate forest|
|1800–2400 m||537 032||13.4||warm temperate forest/semi-humid subtropical forest|
|1200–1800 m||504 970||12.6||semi-humid subtropical forest/humid subtropical rainforest|
|600–1200 m||392 755||9.8||semi-humid subtropical forest/humid subtropical rainforest|
|0-600 m||212 408||5.3||semi-humid subtropical forest/humid subtropical rainforest|
|Total area||4 007 700||100.0|
Depending on latitude and predominately altitude, the climate varies considerably having a distinct winter and summer season with the latter increasingly characterized by the monsoon rains as latitude decreases. Table 1 also shows the natural vegetation categories most likely to be found in the altitude zones with the climate as the main determining factor for their occurrence.
As arable crops are restricted to lower elevations and the valleys, forest remains the dominant land cover, occupying about 72.5 percent of the total land area (MoA, 1997). The second largest group referred to as “Others” in Table 2, is wasteland with about 15.7 percent of the total area, comprising areas of permanent snow cover, glaciers, rock, water spreads, landslides as well as marshy areas.
Photo 2. Overgrazing along with excessive charcoal and fuelwood production often jeopardise efforts to introduce sustainable forest management
Within agriculture, the dominant land uses are Kamzhing (dryland), Chhuzhing (irrigated/wetland) and Tseri (slash and burn cultivation), where Tseri constitutes a permanent threat to nearby forest stands. Another burden on forests is Tsamdro (pasture) since improved pasture is still being developed and the state forests remain the major pasture areas for livestock rearing. The area under horticulture growing oranges, apples and cardamom as cash crops, is expanding (MoA, 1997).
Photo 3. Shifting cultivation constitutes a permanent threat to forest in rural areas
As outlined above Bhutan contains a wide range of vegetation zones linked to an equally wide range of elevations. The sub-tropical forest type in the south along the Assam-Indian border at elevations between 200 and 1 000 m above sea level with rainfall of 2 500 to 5 000 mm per year (Roetzer, 1996) is characterized by a great variety of sub-tropical species and includes some tropical genera of high commercial value.
Table 2. General information on land cover in Bhutan (after MoA, 1997)
|Coniferous forest||10 616||26.5|
|Broad-leaved forest||15 107||37.7|
|Scrub forest||3 258||8.1|
|Slash and burn cultivation||883||2.2|
|Mixed cultivated land||840||2.1|
|Total area||40 077||100.0|
Note: “Others” comprises areas of permanent snow cover, glaciers, rock, water spreads, landslides and marshy areas
Higher elevations, from about 1 000 to 2 100 m with lower precipitation of about 2 300 to 4 000 mm per year, are covered by another type of sub-tropical forest containing a mixture of evergreen and deciduous broad-leaved species. Forest stands in this type of forest are characterized by the absence of tropical species, which are replaced by temperate and sub-temperate broad-leaved species that have often been cleared for grazing (Roetzer, 1996).
At elevations above 2 000 m above sea level two types of forest, a drier Evergreen Oak Forest and a Moist Broad-leaved Forest, dominate. Between 2 700 and 3 200 m altitude a Spruce Forest type occurs, somewhat below the spruce forest belt a Hemlock Forest type can be found. The forest type at the highest elevations from 3 200 m up to 3 900 m is the Fir Forest.
In addition to the forest types listed above two other distinct forest types, namely the Blue Pine Forest and the Chir Pine Forest, occur depending on aspect, soil fertility and moisture. The latter occurs in dry, low elevation valleys at altitudes of about 700 to 2 000 m with precipitation between 1 000 and 1 500 mm per year. Chir pine forms pure, widely spaced timber stands with little shrub understorey due to frequently occurring forest fires. At higher elevations between 2 100 and 3 000 m above sea level the dry slopes are occupied by blue pine forest.
The above given altitude range for each forest type refers particularly to Eastern Bhutan where the studies were carried out and might slightly differ in other parts of the country. Table 3 shows the forest cover of Bhutan by forest categories according to MoA (1997) where land cover has been described as observed on remote sensing materials and through field verification in certain areas.
Table 3. Forest cover of Bhutan by classes and categories (after MoA, 1997)
|Class and category||Symbol||Bhutan|
|Coniferous forest||FC||1 061 600||36.6|
|Mixed conifer||FCm||486 800||16.8|
|Blue pine||FCb||128 600||4.4|
|Chir pine||FCc||100 900||3.5|
|Broad-leaved forest||FB+FBc||1 510 700||52.0|
|Broad-leaf||FB||1 374 900||47.3|
|Plantation forest||FP||6 400||0.2|
|Conifer plantation||FPc||2 000||0.1|
|Broad-leaf plantation||FPb||4 400||0.1|
|Scrub forest||FS||325 800||11.2|
|Forest||F||2 904 500||100.0|
Note: FCf fir forest
FCm mixed, but dominance of conifers
FCb occasionally other species (spruce, broad-leaved)
FCc occasionally broad-leaved species (e.g. oak)
FBc 20–40% conifers
FPc >50% conifers
FPb >50% broad-leaved species
The total forest area of about 2.3 million ha (Table 4) considered for forestry development planning must be reduced by forests in proposed protected areas, alpine areas or critical watersheds to obtain the gross “utilizable” forest area available for forest management. Areas of forest at altitudes above 3 800 m and on slopes steeper than 100 percent are also excluded from commercial timber harvesting. The net “utilizable” forest available for commercial timber management is reduced to about 27.9 percent of the total forest area (Table 4).
Table 4. Forest area by availability for commercial timber utilization (after MoA, 1991)
|Total forest area||2 293 000||100.0|
Proposed protected areas
Critical watersheds/alpine areas
|Gross utilizable forest area||902 000||39.4|
Altitude > 3800 m/slope > 100%
|Net utilizable forest area||639 000||27.9|
The estimated growing stock of the net utilizable forest area of Bhutan is about 135 million m3 according to MoA (1991), the annual allowable cut (AAC) is estimated to be about 923 000 m3. The estimated growing stock gives the standing timber volume over bark, whereas the estimated volume of AAC refers to volume of sound logs under bark. Detailed information on utilizable forest areas, the estimated growing stock and AAC by main catchment areas and/or sub-catchment areas can be found in Appendix 1.
Any commercial timber harvesting operation in Bhutan is based upon the prescription given in the approved forest management plan for a particular FMU. Although the industrial roundwood production of about 45 000 m3 in 1997 (FAOSTAT, 1998) is still far below the abovementioned AAC, sustainability of timber supply is a matter of concern in certain areas due to excessive charcoal and fuelwood production disregarding approved forest management plans.
These forest management plans have been established by the Forest Services Division (FSD) under the Ministry of Agriculture (MoA). Their implementation is monitored by the Divisional Forest Officer. The actual harvesting operation is either carried out by FDC itself or sub-contracted by private contractors. FDC is an autonomous body, familiar with mechanized timber harvesting.
Photo 4. Pit sawing is still common practice in timber processing for local use
Commercial timber harvesting operations are mechanized. By contrast, felling and cross-cutting of trees for local use by villagers for construction or fuelwood purpose is done by axe and/or hand saws. In some areas chain saws are increasingly being used whenever they can be made available (Roetzer, 1996).
Manual processing of felled trees in non-commercial timber production is still common practice in Bhutan. Smaller trees are converted into construction wood simply using an axe to produce one single squared piece of wood (cham) per tree or log. Larger trees are skilfully converted into lumber by pit sawing where the log is rolled onto a simple platform at the felling site. Sawing is done with a peg-toothed handsaw, about two metres long, pulled vertically by one man on top and one underneath the platform (Photo 4). Poles, small logs, chams and hand sawn construction wood are usually extracted manually to the road side or directly to construction sites.