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Grazing resources for yak production systems in Bhutan

W. Roder

Renewable Natural Resources Research Centre (RNRRC), Ministry of Agriculture, Jakar, Bumthang, Bhutan

Summary

Bhutan has extensive grasslands, covering approximately 10% of the total land area. This resource is the base for the transhumance yak production system prevalent throughout the northern regions of the country. Although Bhutan has a relatively young research programme with limited resources allocated to the yak production system, a remarkable amount of information has been generated. This paper reviews information relating to grazing resources, especially that pertaining to the description of plant species and communities, production potential, resource management and quality monitoring.

Keywords: Bhutan, grazing resource, production system, yak

Introduction

Fodder resources

Fodder resources used in Bhutan vary with climate, farming system and season. It was estimated that the grazing of natural grassland (including fallow land), forest grazing, improved pasture, fodder trees and crop residues, would contribute to 38, 23, 9, 15 and 13%, respectively, of the fodder requirements for ruminants of Bhutan (Roder et al. 1998). Natural grassland above the tree line (alpine grazing land) is the main fodder resource for yak. During winter additional fodder is provided consisting of hay, crop by-products (including residues of alcohol making) and turnip.

Grassland species and ecology

The book Flora of Bhutan (in progress), especially the recent volume on the grass family (Noltie 2000), provides an important base for the description of grassland communities. Following a recent review, the dominant species in alpine grazing lands were identified as belonging to the genera: Carex, Juncus, Agrostis, Festuca, Kobresia, Poa, Rododendron, Potentilla, Primula and Danthonia (Roder et al. 1998). Many authors tend to be subjective in their descriptions, influenced by seasonal trends in vegetation cover and by specific interests. Grassland or rangeland specialists generally emphasise grass species (Miller 1987). Vegetation measurements made at altitudes ranging from 31004300 metres above sea level (masl), however, showed that broadleaf species provide the bulk of the vegetation cover (Table 1). With an increase in altitude sedges gradually replace grass species. A first attempt to delineate grassland types depending on elevation and precipitation was made by Tsuchida (1991). This classification can be used as a base for further refinement.

Table 1. Percent vegetation cover and composition for selected regions.1

Region

Altitude (masl)*

Sites

Broadleaf (%)

Grasses (%)

Sedges (%)

Bare ground2 (%)

1. Laya

38004000

3

44 (4147)3

16 (1223)

15 (922)

26 (1735)

2. Laya

41004200

5

46 (2070)

8 (119)

25 (1535)

21 (638)

3. Lunana

41004800

4

41 (483)

15 (146)

30 (091)

15 (130)

4. Lhingshi

44004600

3

42 (1272)

9 (712)

16 (630)

33 (575)

5. Domchen

41104300

4

61 (4967)

8 (315)

29 (2135)

1 (03)

6. Gorsum

32103360

3

45 (3653)

25 (1141)

14 (817)

15

1. Methods used were: Region 14, visual estimates from plots of 0.1 m2 (Gyamthso 1996); Region 5 and 6, point method along line transects (Wangdi et al. 1999).
2. Including moss.
3. Values in bracket indicate range observed across sites for a particular region.
* masl = metre above sea level.

Grassland production

The country has over 400 thousand hectare of registered grazing land or Tsadrog. Registered as a specific land use class that cannot be diverted to other uses, these grazing lands belong only to the state and herders who have grazing rights.

To date, no reliable data on native grassland production under existing herders' or farmers' management are available. Several observers have estimated production based on one single visual observation, others have physically measured the dry matter production under total exclusion of grazing animals (Roder et al. 1998), Figure 1. Following these estimates the dry matter yields range from 0.73.0 t/ha for temperate grasslands at elevations <3000 masl and 0.33.5 t/ha for alpine grasslands at elevations >3000 masl. Estimates based on actual measurements are generally lower as compared to estimates based solely on visual assessments. With an increase in altitude the vegetative period declines. Figure 2 shows expected production using a simple model by extrapolating from maximum yields observed at 2700 masl and the growing days calculated based on the frost-free period. The work by Gyamthso (1996) confirmed that high dry matter yields are possible at elevations of 4000 masl.

          

Figure 1. Existing grassland yields.            Figure 2. Potential grassland production.

Grassland management

Natural environment and the socio-economic setting in which they operate influence herding systems. Herders generally use sound management with rotational grazing. Households with small herds often pool their animals together. Most herders have grazing rights for one or more pastures either individually or on a community basis. In some regions absentee landlords own large areas of grazing land. A unique system used for allotting communal pastures to herders was described for Ha district (Ura 1993). Grazing areas in the vicinity of permanent settlements at middle elevations (20003000 masl) are often used by cattle for summer grazing and by yak for winter grazing (Gyamthso 1996). It is not uncommon for two parties, such as a transhumant yak herder and a family from a nearby settlement, to have grazing rights for the same area.

Overgrazing is frequently mentioned as the main cause of low and/or deteriorating grassland yields, or a threat to the environment. No information is, however, available on livestock numbers and grazing pressure prior to 1960.

Forest and grassland communities include a large number of poisonous plant species such as Aconitum sp., Senecio sp., Euphorbia sp., Pteridium sp., Eupatorium adenophorum etc. (Roder et al. 1998). Animals generally do not graze these species except under abnormal circumstances such as lack of other feed sources, exhaustion (caused by long distance travel, heavy pack loads etc.), or other stressful situations.

Wildlife interactions

Grassland resources support a wide range of wild animals of which the takin (Budorcus taxicolor), the blue sheep (Pseudovis nayaur), the sambar (Cervus unicolor) and the musk deer (Moschus chrysogaster) are the most important. In recent years some of these species, especially the blue sheep, have increased, supposedly due to a decline in the population of its predators. Herders in the Laya region claimed that grazing resources have deteriorated due to an increase in blue sheep populations (Gyamthso 1996). Another wildlife species, which has substantially increased its population, is the wild boar.

Resource monitoring

A programme was initiated in 1997 with the objective of monitoring trends in species composition, biomass production, soil cover and soil quality (Wangdi et al. 1999). Under this programme, permanent observation plots have been installed in Domchen and Gorsum (Jakar), Soi-Yaksa (Thimphu) and Merak-Sakten (Trashigang). Individual observation plots, consisting of a circle with an area of 452 m2 (r = 12 m), have been marked using a global positioning system (GPS) and iron pegs. Soil samples have been archived and the vegetation cover was recorded using points along a line transect. Vegetation changes will be documented through observations taken in 5-year intervals.

Potential for increased grassland production

Comparing the existing and the potential dry matter production, there appears to be substantial room for increased fodder production (Figures 1 and 2). Techniques such as control of unwanted shrubs, grazing management, introduction of legumes and P-application are available. The traditional use of fire to control unwanted shrubby species is presently illegal, but possible changes in the law allowing for controlled burning are under discussion. Combined effects of white clover introduction and P-application resulted in dry matter yield increases of 813, 317 and 64% for elevations of 2700, 3300 and 4020 masl, respectively (Roder et al. 1998). Most authors agree that increasing winter fodder availability and quality should be given priority. Lucerne, white clover, tall fescue, and cocksfoot and oat are the most promising species for this.

References

Gyamthso P. 1996. Assessment of the condition and potential from improvement of high altitude rangelands of Bhutan. PhD thesis, Swiss Federal Institute of Technology, Zurich, Switzerland. 249 pp.

Miller D.J. 1987. Yaks and grasses: Introductory notes on pastoralism in the Himalayan Kingdom of Bhutan and the potential for development. Bhutan Journal of Animal Husbandry 9:5459.

Noltie H.J. 2000. The grasses of Bhutan, flora of Bhutan, including a record of plants from Sikkim and Darjeeling. Vol. 3, Part 2. Royal Botanical Garden, Edingburgh, England. pp. 457476.

Roder W., Wangdi K., Gyamtsho P. and Wangdi K. 1998. Feed and fodder research and development in Bhutan. RNR-RC Jakar, Bhutan. Special Publication 1. 135 pp.

Tsuchida K. 1991. Grassland vegetation between the tropical and subalpine zone of Bhutan. In: Oshawa M. (ed), Life zone ecology of the Bhutan Himalaya II. Laboratory of Ecology, Chiba University, Japan. pp. 189219.

Ura K. 1993. The nomads' gamble. South Asia Research 13(2):81100.

Wangdi K., Roder W. and Dorji K. 1999. Botanical composition of native pastures in Bumthang. In: Proceedings of the fourth annual national livestock research co-ordination workshop held in Bathpalathang, Bhutan, 2729 January 1999. pp. 5254.

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