INTRODUCTIONThe Himalayas constitute one of the richest and most unusual ecosystems on earth. TheHimalayan alpine areas are characterized by low productivity, high intensity of solar radiationand high degree of resource seasonality. The vegetation of this fragile biome is adapted to theextreme conditions occurring with sparse populations. Himalayan high altitude grazing pasturesare very important being a wild life habitat, water catchment and a livelihood source for nomadicand transhumant inhabitants. The community structure and distribution patterns of Himalayanforests and alpine pastures have not been given due attention till the date by the plant ecologists,and hence poorly understood (Peer et al.,2007). The distribution and community structure of alpine vegetation is governed by adverseedaphic and climatic factors; mainly by rainfall and redistribution of water that decrease with theincrease in altitude. Temperature is also one of the most important limiting factors controllingthe distribution and community structure of Himalayan vegetation. Here the altitude has muchgreater effect on temperature than latitude. Mean annual temperature decrease with increase inelevation, more rapidly in summer than in winter. This altitude based temperature gradient is thevital factor shaping the vegetation types and determining their diversity and distribution (Heaneyand Proctor, 1989; Tanner et al., 1998; Vazquez and Givnish, 1998).Alpine areas are characterized by scanty rainfall, high ultraviolet (UV) radiation, high windvelocity, blizzards, low temperature and snowstorms. The plants of this zone show an adaptationto these conditions and are generally dwarfed, stunted, wooly or spiny, and develop a mosaicpatch of different forms. They possess an early growth initiation with a short vegetative spanranging from several days to a few months. The community as a whole usually exhibits seasonalfluctuations, and its structure and composition are strongly influenced by the extent to whichperiodic phenomena in the individuals are adjusted to each other (Kershaw, 1973). In Pakistan,alpine pastures cover 1050,000 hectares, which makes 1% of country area lying between snowand tree line at an average altitudinal range of 2500 to 4000 m 600 J. Med. Plant. Res.(Sardar, 1997). These pastures are used for grazing during March-April to September–Octoberand for rest of the time these remain under snow. Western Himalayan pastures are severelydegraded due to nomadic and sedentary livestock overgrazing. Due to huge population increasesand frighteningly increasing urbanization practices, existing reserve forests and grazing lands areoverburdened with community rights making it impossible to reduce the grazing pressure(Gupta, 1970, 1977). Grazing practices are one of theimportant determinants of vegetationdistribution patterns and having most obvious impact on the floral biodiversity of an area(Vallentine, 2001). Many researchers (Vigne, 1842; Duthie, 1892; Stewart, 1961; Dickore, 1995;Negi, 1995; Sardar, 1997; Stainton, 1998; Shinwari and Gillani, 2002)
have studied different aspects of vegetation structure and distribution patterns in alpines ofwestern Himalayas. Phytosociology or plant sociology is an invaluable method for vegetationsurvey and assessment involving investigation of characteristics of plant communities usingsimple and rapidly employing field techniques (Rieley and Page, 1990). In the present study, aneffort has been made to investigate and analyse correlation of vegetative attributes with keyenvironmental factors using themultivariate analyses techniques.MATERIALS AND METHODSThe study area lies in Deosai plains in the great Himalayan range, Northern Pakistan. The area isuninhabited grassy plateau with an average altitude of 411m. The Sheosar Lake is situated at anelevation of 4,142 m having length 2.3 km, width 1.8 km (1.2 miles) and average depth 40 m.Area exhibits very harsh climatic conditions having long and severe snowy winters from Octoberto May. In whole winter area remains snow covered and temperatures always below the freezingpoint. It has a very short growing spring season from May to July. The study area has veryunique geographic location lying between the western Himalayan massif and Karakoram rangecovering 1400 km². Deosai is also called „Roof of the earth‟ and „the land of Giants‟ . Thephytosociological expeditions were carried out in the JuneJuly, 2008 to the Deosai plains. Linetransect method was used to study and analyse the vegetation dynamics as well as to collect theprimary data for statistical analyses. Transects were laid in selected sites having bestrepresentation of floral biodiversity and geographic extent of the area. A total of 15 transects, 10m each were laid in the study area. Vegetation attributes including frequency, density, cover andrichness were recorded along with environmental coordinates like latitude, longitude, altitudeand slope using GPS. Plants from the premises of sampling points as well as isolated vegetationpatches were also collected to record maximum number of species and their distribution patterns.Collected samples were pressed, dried and transported to herbarium of Quaid-I-Azam UniversityIslamabad, Pakistan, where they were identified and classified following Stewart (1961) andNasir and Ali (1972). Deterrended correspondence analyses (DCA) was applied to the speciesabundance data by using reciprocal averaging ordination (Hill, 1980). The primary dataregarding species cover and abundance was analyzed to determine natural plant associations aswell as to measure the variations in dynamics and distribution of species.RESULTS AND DISCUSSIONA total of 114 species belonging to 28 families were recorded during the field expeditions.Compositeae was the leading representative of local flora comprising 13.15% of cover followedby Ranunculaceae with 10.52%. Cruciferae, Gramineae, Leguminosae, Scrophulariaceae,Apiaceae and Polygonaceae were the co dominant families in the study area.The study arearepresented a mosaic of meadow, open scree, scrub and rock vegetation types. Rich soil moisturewith cold climate has resulted in the accumulation of rich humus layers enabling tall
hygrophilous forbs like Aconogonon, Gentiana and Geranium to grow along with smaller herbslike Vicatia, Sibbaldia and Pedicularis. Saussurea, Androsace, Rhodiola, Saxifraga, Myosotis,Erigeron, Draba, Trollius, Thalictrum, Potentilla, Carex Oxytropis, Ranunculus, Leontopodiumand Chorispora were the dominant species making the major framework of community structureand distribution.The distribution of vegetation is controlled by complex edaphic, climatic and anthropogenicfactors like exposure, humidity and grazing intensity. Salix and Primula populations were mainlyconfined to permanently moist, snow covered trails. Scrub and dwarf scrub "Krummholz" ofSalix karelinii were found to be attaining a height up to 100 cm mostly covering the North facingslopes having low grazing pressure. South facing slopes represented much drier conditions and agreater grazing intensity, mostly colonized by chamaephytes and drought resistant herbs likeBistorta affinis, Elymus, Silene, Oxytropis and Rhodiola. The intermediate rocky slopes werecharacterized by open scree plant communities. The two major plant associations developed as aresult of species data analyses were as follows:Carex cruenta – Geranium himalayense – Bistorta affinis communityThe dominant species included C. cruneata and G. himalayense with indicator species B. affinisand Rosularia rosulata. This association was a characteristic feature of most North facing slopeshaving maximum soil moisture and less grazing intensity.Sibbaldia cunneata–Saxifraga flagellaris– Eragrostis communityThis plant community was dominated by Sibbaldia and Saxifraga species exclusively growing increvices and low moisture places. Avena fatua and Leontopodium were among the indicatorspecies of this community.Detrended correspondence analysisDCA results showed very clear and understandable distribution of vegetation communities alongDCA axis 1. The three positively valued communities were aggregated on the left separated fromthe CarexGeranium-Bistorta community at the right. The 1st axis indicates soil moisture gradientas the major limiting factor controlling the structure and distribution of plant communities. Theaggregation of communities in the drier region can be easily interpreted to support theassumption (Malik and Husain, 2006). Community distribution trend along the DCA axis 2 is not
clear as several edaphic and biotic factors appear to be acting together. The species compositionof Carex-GeraniumBistorta found atmesic site showed negative correlation with the moisturegradient, whereas other plant associations were restricted to drier area.Chorological spectrumThe chorological spectrum of Sheosar lake flora revealed the lowest proportion ofcosmopolitan species (<5%) 2 Axis 1 where as Eurasiatic elements were the top ones (27%).The endemic to Hindukush Himalayan members made 15% of the total local flora (Figure 3).Centrasiatic and Sino-Himalayan elements showed medium trends. Minor proportions of florashowed affiliations with IranoTuranian, Tibetan, Mediterranean and Circumpolar regionsrepresenting a high degree of endemism.CONCLUSION AND RECOMMENDATIONSThe area still needs very detailed and comprehensive investigations regarding differentvegetative attributes and their correlation with environmental as well as anthropogenic variables.A single study can not serve the whole purpose in such a large, diverse and geographicallyimportant area. Repeated and integrated explorations are recommended in all parts of Deosaiplateau to explore the dynamic and variations in floral biodiversity. Grazing practices need to belimited and monitored along with creating the awareness among the grazers about conservationand sustainable management of grasslands. Fenced vegetation plots should be designed atregular intervals to act as seed banks in602 J. Med. Plant. Res.Number of speciesNumber of species whole plateau. Grazing practices should be synchronized with plant growthseasons so that damage to vegetation during flowering stage can be avoided. A great deal canbe done about the ethnobotanical application of the local flora by identifying, investigating andevaluating the utilization practices of local folklore. The most important point to be consideredis conservation of endemic flora, which has its restricted distribution in the study area and is
posed with severe threats due to overexploitation by grazing, medicinal plant harvest and harshenvironmental conditions.REFERENCESDickore WB, Nusser M (2000). Flora of Nanga Parbat (N.W Himalaya,Pakistan). An Annotated inventory of vascular plants with remarks onvegetation dynamics. Englera, 19: 1-253Duthie JF (1906). Catalogue of the Plants of Kumaon and Adjacentportions of Garhwal and Tibet Based on the Collections made byStrachey and Winterbottom during the Years 1846–1849, LovellReeve and Co, Ltd, London.Gupta RK, PC Nanda (1970). Grassland types and their ecologicalsuccession in Western Himalaya. Proc. Intern. Grassland Congr., pp.10-13.Gupta RK (1977). Energy Forests on Farm and Community Lands - N.W. Himalayan region. Indian Farming, 26(11): 84-86.Heaney A, J Proctor (1989). Chemical elements in fitter at a range ofaltitude on Volcan barva, costa Rica: Nutrients in Tropical Forest andSawanna Ecosystems. (Ed.): J. Proctor. Blackwell Scientificpublications, Oxford, pp. 255-271.Hill MO, HG Gauch (1980) Detrended correspondence analysis: animproved ordination technique. Vegetation, 42: 47-58.Kershaw RA (1973). Quantitative and Dynamic Plant Ecology. London:Edward Arnold.
Malik RN, SZ Husain (2006). Classification and ordination of vegetationcommunities of the Lohibehr reserve forest and its surrounding areas,Rawalpindi. Pak. J. bot., 38(3): 543-558.Nasir E, SI Ali (1972) Flora of West Pakistan. An annotated catalogue ofvascular plants of West Pakistan and Kashmir.Shaheen and Qureshi 603Negi SS (1995). Cold deserts of India. Indus Publishing Company, NewDelhi.Peer T, JP Gruber, Millingard A, Hussain F (2007) Phytosociology,structure and diversity of the steppes vegetation in the mountains ofNorthern Pakistan. Phytocoeno., 37: 1-65.Rieley J, Page S (1990) Ecology of plant communities: Aphytosociological account of the British Vegetation. John Wiley andsons, Inc., New York, p. 178.Sardar MR (1997). Indigenous Production and Utilization Systems in theHigh Altitude Alpine Pastures, Saif-ul-Maluk (NWFP), Pakistan, PFI,Peshawar, p. 47.Shinwari ZK, SS Gilani, Khan AA (2002). “Wise-practices andexperiential learning in the conservation and management ofHimalayan medicinal plants” In the regional workshop held atKathmandu, Nepal from 15 – 20th December 2002.Stainton A (1998). Flowers of the Himalaya. A Supplement, OxfordUniversity Press.
Stewart RR (1961). The Flora of Deosai plains. Pak. J. For., 11: 225295Tanner EVJ, PM Vitousek, Cuevas E (1998). Experimental investigationof nutrient limitation of forest growth on wet tropical mountains. Ecol.,79: 10-22.Vallentine JF (2001). Grazing Management. Academic Press, SanDiego/San Francisco/New York/Boston/London/Sydney/Tokyo.Vazquez JAG, Givnish TJ (1998). Altitudinal gradients in tropical forestcomposition, structure and diversity in the sierra de Manantlan,Jalisco, Mexico. J. Ecol., 86: 999-1020.Vigne GT (1842). Travelsin Kashmir, Ladakh,I scardo, theC ountriesAdjoining the Mountain-courseo f the Indus, and the Himalaya, Northof the Panjab. 2 Vols. H. Colburn, London.Access This File on Respected Blog