International Journal of Fieldwork Studies, 2004 2 (1)

Community composition, species diversity, and secondary succession in grazed and ungrazed alpine meadows of the West Himalaya, India

Dr. Chandra Prakash Kala

Environment and Mountain Development Institute, V.P.O.- Sumari, Pauri Garhwal, Uttaranchal- 246 174, India
cpkala@yahoo.co.uk

Abstract

The Valley of Flowers National Park (VOF) lies in the Western Himalayan region of Indian sub-continent is well known across the world for its rich floral diversity. Livestock (sheep, goats and mules) grazing has been stopped in this park since 1982. The plant community composition, and species diversity were studied in the VOF and these parameters were compared with the similar unprotected alpine meadows using stratified random quadrats of 0.25 m². TWINSPAN was used to separate the communities and Shannon Wiener Index (H') was used for species diversity. The main valley portion in the VOF that falls between 3,300-3,700 m obtained 9 plant communities whereas in unprotected valley at similar elevation obtained only 7 plant communities. Along an altitudinal gradient the species diversity decreased with elevation in both protected and unprotected meadows. In VOF species diversity was higher (H'=2.93) than the Khiron Valley (H'=2.77). The results are discussed along with the management implications.

Key Words

Himalaya, alpine meadows, protected areas, grazed areas, species diversity, species richness

Introduction

The high altitude vegetation above treeline zone in the Himalaya has been a subject of considerable interest among the naturalists, phytogeographers and ecologists (Mani, 1978; Rau, 1975). The forest formations below tree line zone (3,500±200 m in the western and 3,800±200 m in the eastern Himalaya) have derived largely from the tropical forests of Peninsular and Indo-Malayan origin, whereas the land above this zone has been vegetated only towards final phase of Himalayan orogeny (Vishnu Mittre, 1972; 1984). The colonization of high altitude alpine habitats by high altitude flora was gradual and continues till date as every year new habitats and landforms are created due to fluvial and colluvial actions. A closer look at the present day high altitude meadow vegetation reveals interesting facts of past geo-climatological changes and human interventions.

Various vegetation formations of high altitude or alpine region viz., krummholz, alpine scrub, meadows and pioneer communities near snowline characterize different edaphic and climatic conditions. Of these, the meadows are regarded as most stable formations that are generally located on the gentle to steep slopes. Unlike the anthropogenic grasslands of temperate and tropical regions, which are dominated by grasses the alpine meadows are governed by climate and abound in perennial dwarf herbs, mosses, and sedges (Mani, 1978). Alpine meadows cover an area of 171,464 km² in the Indian Himalaya, of which the present study area Uttaranchal Himalaya contributes 16.60 % area (Lal et. al., 1991).

The high altitude meadows in Himalaya are locally known as 'Bugyal' in Uttaranchal and 'Marg' in Kashmir and are used as summer grazing grounds by several migratory and local pastoral communities. Other communities collect wild medicinal herbs from these areas so as to sell in the market and earn their livelihood. Continuous and heavy use of many alpine areas have led to degradation of pastures, soil erosion and resultant problems. There have been studies of the floral characteristics and biomass production in alpine meadows (Semwal and Gaur, 1985; Ram et. al., 1989; Sundriyal and Joshi, 1990; Rikhari et. al., 1992; Negi et. al., 1993; Kala, 1998) but there is paucity of studies on species diversity and impact of livestock removal from the high altitude Protected Areas.

There is no precise strategy for the conservation and management of high altitude areas due to a lack of ecological and quantitative data, there is an ongoing debate on the nature and extent of use of the meadows (Kala, 1998, 1999, 2002). There is also the lack of any comprehensive management plan for any alpine meadows. This paper presents a case study from the Valley of Flowers National Park, Western Himalaya, which was established in 1982 to conserve its diverse plant communities and fragile ecosystem. The species diversity and structure of ungrazed plant communities are compared with those of grazed meadows in adjacent valleys. The effect of protection on selected plant species and management issues are also discussed.


Study Area

The study was carried out in the Valley of Flowers National Park (VOF) and adjacent grazed area i.e. Khiron Valley located in the Chamoli district of Garhwal Himalaya (30?41'-30?48' N and 79?33'-79?46' E). The VOF forms the upper catchment of river Bhyundar, which drains into river Alaknanda, a major tributary of Ganga. The VOF is nestled among the snow-clad summits viz., Nilgiri Parvat (6,407 m), Gauri Parvat (6,590 m), Rataban (5,400 m), Sapta Sringa (5,025 m), and Kunt Khal (5,855 m). The altitude ranges from 3,200 m to 6,590 m. As the VOF received wide spread attention of tourists and plant explorers from all over the world, the then State Government of Uttar Pradesh, India notified its 87.5 sq. km area as a national park in 1982. With the upgraded status of the valley from the Reserve Forest to the national park it was also ensured that the resident fauna such as Himalayan musk deer (Moschus crysogaster), serow (Nemorhaedus sumatraensis), Himalayan tahr (Hemitragus jemlahicus), Himalayan black bear (Selenarctos tibetanus) bharal (Pseudois nayaur), Mouse hare (Ochotona royeli), red fox (Vulpes vulpes), Himalayan weasel (Mustela sibirica) and a variety of birds is also protected. In accordance with the provisions contained in the Wildlife (Protection) Act 1972, domestic livestock grazing was stopped within the national park although, transhumant pastoralism continues in the vicinity of the park viz., Khiron Valley and Kakbhusandi. Soon after ban on the grazing a controversy arose which is attributed to the proliferation of Polygonum polystachyum, Impatiens sulcata and Osmunda clatoniana in the national park area. Therefore, the VOF management initiated the eradication of Polygonum polystachyum initially by uprooting and thereafter cutting.

The Khiron Valley is approximately 12 km by 3 km in size. The main landform characteristic is an undulating terrain with flat plateau and steep slopes. The area is bounded by famous Nilkanth peak (6,498 m) in the North. Approximately 4200 sheep and goats graze in the alpine meadows of Khiron Valley during the summer season (June to October). Besides the sheep and goats, some wild animals like Himalayan tahr, Himalayan musk deer, blue sheep, serow, mouse hare, Himalayan black bear, red fox, Himalayan weasel, and common leopard (Panthera uncia) are seen occasionally in this valley.

Meteorological data was collected during the snow free period (May-October). The mean daily maximum temperature was ranged from 8.80C to 220C and minimum temperature from 3.00C to 10.50C. The total rainfall during summer (May-October) was estimated 1075 mm, of which highest was in August (383.5 mm). Relative humidity varied between 80-100 %. Snowfall begins in November and continues till April, but on the high peaks it keeps on falling throughout the season. Cloud and fog formation are regular features and the period of clear sky is limited for only a few morning hours each day.

Methods

Two alpine meadows in Uttaranchal Himalaya viz., the Valley of Flowers and the Khiron valley were selected for sampling as both the valleys stretch out above treeline zone and obtain herbaceous vegetation with scanty dwarf shrubs. Although, there is a difference in land use pattern in both the valleys as the Valley of Flowers is a National Park and anthropogenic activities including livestock grazing have been banned since 1982. On the other hand, anthropogenic activities are continue in the Khiron valley and more than 4000 sheep and goats graze the valley during summer. These conditions have provided an optimum situation to study the vegetation composition and species diversity across two different situations, and also to set a comparison between grazed and ungrazed alpine meadows.

Sampling was made along an altitudinal gradient in both the valleys by using randomly placed quadrats of 50x50 cm. The number and size of quadrats were determined following Misra (1968). In each valley a total of 500 such quadrats were laid. All plant species with their individuals were enumerated in each quadrat. In case of tussock forming species such as Danthonia cachemyriana only estimated number was used. Plant species in the study area were identified using floras viz., (Hooker, 1872-97; Rau, 1975; Polunin and Stanton, 1984). Soil samples were collected from different places of both the valleys for analysis of soil pH, soil organic carbon and soil nitrogen.

Vegetation classification has performed by polythetic divisive clustering with the TWINSPAN (two way indicator species analysis) computer package (Hill, 1979). TWINSPAN begins with all samples together in a single group, or cluster, and successively divides each cluster of samples dichotomously into a hierarchy of smaller and smaller clusters until a specified cluster size of number of divisions are attained. I limited the classification to a maximum of five division levels, because cluster size became too small for reliable interpretation with more divisions. Psuedospecies cut-levels were not set. All program options were at default levels. To estimate plant species diversity, Shannon-Wiener diversity index (Shannon and Weaver, 1949) H'= S pi log pi was applied, as the index makes the assumption that individuals are randomly sampled from an infinitely large populations (Kent and Coker, 1992). In the index pi refers to the proportion of individuals of ith species. Species richness was calculated by Menhinick's index following Whittaker (1977). Besides, the observations were made in the field on the secondary succession across the various localities from forested areas to the freshly eroded slopes.

Results and discussion

Plant community composition and species diversity
A total of 194 herbaceous plant species were sampled in the valley portion of the national park between 3,300-3,700 m elevation. TWINSPAN computer package segregated 11 plant communities, of these 4 plant communities were common in both the valleys e.g. Valley of Flowers and Khiron valley. The Valley of Flowers obtained a total of 9 plant communities (Table 1), whereas the Khiron valley obtained 6 plant communities (Table 2). Most of the communities were composed of forb species. Three communities were predominated by grass/sedges such as Kobresia royleana and Danthonia cachemyriana.

Table 1: Species diversity and richness of various communities in the Valley of Flowers National Park

Table 2: Table 2: Plant communities, species diversity, and richness in the Khiron Valley

The highest diversity (H’=2.93) was found in Cortia lindlei-Ranunculus hirtellus community, followed by Calamogrostis emodensis-mixed forb community (H’=2.92). The diversity of species decreases with the increase in altitudes (Table 1). The richness value was found highest (1.24) in Danthonia cachemyriana community, followed by Calamogrostis emodensis - mixed forb community (1.17), while it was lowest (0.72 each) in the polygonum polystachyum-mixed forb and Kobresia royleana-Danthonia cachemyriana community. The nature of soil was acidic in all communities as its pH ranged between 3.8-6.2. The range of soil nitrogen was 0.70 % - 1.75 % and organic carbon was 8.92 % - 33.87 %. The highest percentage of organic carbon (33.87) and nitrogen (1.75) was found in the Polygonum polystachyum community.

Polygonum polystachyum-mixed forb community was found in camping sites of sheep and goats. Rumex nepalensis was the first companion species in this community, which is a weed. Almost all herbs in this community were tall and attained approximately 2.00-2.50 m height. Potentilla atrosanguinea-Geranium wallichianum community was chiefly confined to undulating landmasses. Iris kumaonensis-Andropogon munroii was found in pockets on the flatter areas and had the highest diversity value (H’=2.77). Danthonia cachemyriana-Anemone rivularis community was found on steep to gentle slopes. Trachydium roylei-mixed forb was found at much higher altitude (3,800 m) and it was less diverse community.

In the VOF and Khiron Valley four communities were common (Table 3). Two of them (Danthonia cachemyriana, and Geranium wallichianum-Potentilla atrosanguinea) exhibited higher species diversity in the VOF than the Khiron Valley. Polygonum polystachyum-mixed forb community is found in both the valleys (VOF and Khiron Valley) and possessed almost equal diversity (H’=2.30, and 2.32 respectively). The overall range of species diversity in the VOF is larger (H’=1.88-2.93) than the Khiron Valley (H’=1.32-2.72). The high species diversity of VOF is attributed to its diversity of habitats (Kala, 2002). Besides habitat diversity, altitude and livestock grazing also influenced the species diversity as most of the rare, palatable, and valuable species flourished in the ungrazed areas whereas, ruderal, unpalatable, and weedy species increased in the grazing lands.

Table 3: Comparison in species diversity between five common communities of the Valley of Flowers National Park and Khiron Valley

In both the valleys, Danthonia cachemyriana and Polygonum polystachyum community were dominated by one or two species, albeit, these kind of communities in which one species predominates are rare in nature (Harper, 1977). Generally, these communities are formed by hydrophytic or alpine species that spread clonally, or by tall, fast growing species in disturbed areas that shade out shorter and more slowly growing species, or by rhizomatous or stoloniferous grassland species that prohibit seed germination and the growth of other species by producing abundant litter (Harper, 1977, and Grime, 1979). The rarity of communities with strong single species dominance has been attributed to grazing, species competition, seed predation, disturbance, disease, climatic stability and niche diversification (Whittaker and Levin, 1977). In both the areas, however, single species dominated communities were limited.

The places in the VOF from where P. polystachyum has been eradicated by the park management regularly since 1984, Impatiens sulcata has taken over forming Impatiens sulcata-mixed forb community. Species diversity and richness of this community were estimated to be H’=1.90 and 0.49 respectively while the species diversity and richness values in undisturbed Polygonum polystachyum patches were higher i.e. H’=2.15 and 0.72 respectively. The presence and absence of other herbs with P. polystachyum vary with topographical variation, altitude and degree of natural disturbance. P. polystachyum also grows in the higher alpine zone but very few individuals were seen growing solitary and not gregariously.

Successional trend in the VOF
Two courses of succession along the valley bottom in the VOF are evident viz., meadow succession and the forest succession. The substrate for meadow succession is terminal and lateral moraine on the south facing slopes, whereas, north and north-east facing lateral moraines and gorges are the substrate for forest succession. With the colonization of mosses and lichens on the bare inorganic substrate, succession initiates to form meadow or forests. Meadow succession is passed through the invasion of grasses and sedges along with annuals and perennial herbs, whereas, forest succession is passed through only annuals and perennial herbs. Meadow succession is terminated with the installation of Danthonia cachemyriana and Cyananthus lobatus-Kobresia royleana-Anaphalis royleana communities, which might be the climax communities, whereas, forest succession passes through Rubus alpestris-Spirea bella-Cotoneaster microphyllus community and eventually gives rise to Betula utilis and Rhododendron companulatum (Table 4).

Table 4: Succession characteristics

Some plant communities in the VOF are still in early seral stages while others appear to be representing climatic climax. Yadava and Singh (1977) argued that succession in grasslands often intimately associated with grazing pressure. The existence of climax grasslands in India is doubtful although Champion (1936) advocated that under the impact of fire and grazing the grassland community might be fairly stable indicating a pre-climax stage. However, the alpine vegetation represents the climatic climax as the cold and severe climate prevents the encroachment of forests in this zone (Gupta and Nanda, 1970) and additional perturbations (fire and grazing) do not influence these climatic climax communities. Bor (1960) pointed out that true grassland is developed in a climate which is characterised by firstly frequent precipitation of rain, even if the amount is small, to keep the upper layers of the soil moist during growth period and second sufficient warmth during the growing season. VOF receives both frequent precipitation and sufficient warmth during the growing season resulting in some true alpine plant communities viz., Kobresia royleana - Danthonia cachemyriana and Danthonia cachemyriana. Besides, Rhododendron anthopogon-Cassiope fastigiata, Rhododendron campanulatum-Betula utilis and Juniperus communis-Cotoneaster microphyllus represents climatic climax community in the VOF.

The main purpose of the VOF is to ensure in-situ conservation of plants. Accordingly, the species known to have their natural occurrence in the area should be provided perpetual environment of their own, not withstanding the process of ecological succession. I make the following recommendation for the conservation of floral diversity in the VOF: Identification of threatened habitats in the alpine meadows and their restoration, introduction of rehabilitation programme for the recovery of the rare and medicinal plants, establishment of seed, rhizome and tuber bank, checking of Polygonum polystachyum growth on experimental bases for meeting the conclusion, research and monitoring in both protected and unprotected areas, management of tourism, and people participation and collaboration for strengthening the conservation of natural resources.

Conclusions

The VOF in the Garhwal Himalaya is more diverse in terms of species than its adjacent grazed areas. The high species diversity of this park is attributed to its landscape diversity and protection. The number of plant communities in the VOF is also higher than the comparable areas (Khiron Valley). Species diversity decreases with the increasing altitude in both the valleys. Polygonum polystachyum, a tall and fast growing perennial herb grows profusely in disturbed areas in the alpine meadows between 3,400-3,500 m elevation and rarely shares habitats with stable meadows and rare alpine herbs. Therefore, its eradication may not help in the management of the protected areas across the high altitudes of the Himalaya. The lower population of rare plants in the grazed meadows (Khiron Valley) than the ungrazed meadows (VOF) indicates that livestock grazing can lead to decrease in rare plant populations and may promote weedy and ruderal species. Therefore, the current management policy such as protection and ban on livestock grazing in the alpine region should be continued for the long-term survival of these meadows.

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Please cite this paper as:
Kala CP (2004) Community composition, species diversity, and secondary succession in grazed and ungrazed alpine meadows of the West Himalaya, India, International Journal of Fieldwork Studies, 2(1), http://www.virtualmontana.org/ejournal/vol2(1)/succession.htm

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