Journal of Threatened Taxa | | 26 January 2018 | 10(1): 11192–11200




Rhododendron diversity along the Kusong-Panch Pokhari transect in Khangchendzonga Biosphere Reserve, the eastern Himalaya: a conservation perspective


Prem K. Chhetri 1, Bijoy Chhetri 2 & Hemant K. Badola 3

 1,2,3 G.B. Pant National Institute of Himalayan Environment and Sustainable Development, Sikkim Unit, Pangthang, Gangtok, Sikkim 737101, India

1 Forest Environment & Wildlife Management Department, Govt. of Sikkim, Pakyoung, East Sikkim 737106, India

3 Present address: D-408, Aditya Doonshire Apartments, Sailok Phase II, GMS Road, Dehradun, Uttarakhand 248001, India

1, 2, 3 (corresponding author)






Abstract: Sikkim Himalaya, India is part of one of the richest global biodiversity hotspots, exhibiting a significant amount of native flora including Rhododendron (Ericaceae) species, which are particularly well represented with 37 species, 11 subspecies, seven varieties and two natural hybrids occurring along the rolling mountains between 1,500m to 6,000m. Most of the habitats of rhododendrons in Sikkim Himalaya have not only been threatened by climate change but also by emerging eco-tourism and economic activities vis-à-vis trekking corridors. In recent decades, it has been observed that the climate-governed phenology of rhododendrons of eastern Himalaya is shifting; further the urbanization, tourism influx, and clearances for the footpaths have adversely impacted the diversity of many forest areas. To better understand the effects of trekking corridors on Rhododendron species for the tourist destinations, we performed a pilot survey along the Kusong-Panch Pokhari transect in relatively virgin forest of the northern part of Sikkim to assess the status of both Rhododendron diversity and potential environmental management strategies that can be employed within the transect as a new tourist destination in the Sikkim Himalaya. Along with this transect, we recorded 23 Rhododendron species, with five eastern Himalayan endemics. Our results indicate that the diversity of rhododendrons seem good along the Kusong-Panch Pokhari transect and we further recommend it could be a new potential eco-tourism destination as an alternative income generating source for the local people, provided that appropriate conservation management strategies are in place.

Keyword: Conservation management, diversity, eastern Himalaya, Rhododendron, Sikkim, tourist destination.





Occupying 0.2% India’s geographic area of India, the Sikkim eastern Himalaya, is a part of one of the richest global biodiversity hotspots. This is home to over 150 species of mammals, 550 species of birds, 650 species of butterflies and moths, 33 species of reptiles, 16 species of amphibians, 48 species of fishes and over 4,500 species of flowering plants (Sikkim Biodiversity Action Plan 2012; Badola et al. 2016). At present, 37 species, 11 subspecies, seven varieties and two natural hybrids of rhododendrons are reported from Sikkim, which is quite significant when compared with the total number of Rhododendron species (73 species, 22 subspecies, 25 varieties and three natural hybrids) of India (Pradhan & Lachungpa 1990; Mao 2010; Sastry & Hajra 2010). Anthropogenic pressures and other environmental factors have exerted a heavy pressure on the natural availability of many rhododendrons, resulting in several species becoming threatened (Pradhan & Lachungpa 1990; Badola & Pradhan 2010a,b; Gibbs et al. 2011). The deforestation and unsustainable extraction of fuel woods are posing considerable threats to natural populations of rhododendrons in many areas. Climate change, however, is yet another growing threat to the existence of rhododendrons (Badola 2010) besides the burgeoning eco-tourism economics in Sikkim (Menon et al. 2001; Chettri et al. 2002). Many of these rhododendrons are of both economic and cultural importance to the local ethnic people, for their ethno-medicinal and local beverage values. For example, the crushed dried flowers of R. arboreum is used in diarrhoea and blood dysentery (Paul et al. 2005); when mixed with water they help in stopping excessive bleeding in women during menstrual cycles and chewing fresh leaves stops dysentery (Pradhan & Badola 2008). Similarly, the chewed leaf juice of R. campanulatum helps to relieve cough (Pradhan & Badola 2008). The Rhododendron species in Sikkim are abundantly distributed throughout upper-elevation zones, between approximately 1,500–6,000m (Pradhan & Lachungpa 1990). In addition, rhododendrons make thick high altitude shrubberies offering suitable ecological niches to many threatened species as well as charismatic species of pheasants like Ithaginis cruentus and Tragopan satyra, and mammals such as Ailurus fulgens, Pseudois nayaur, Uncia uncia Moschus chrysogaster and so on. Like other parts of eastern Himalaya, the rich floristic diversity of Sikkim Himalayas has been under stress seeking appropriately effective conservation programs (Paul et al. 2005). Many epiphytic species including rhododendrons are in a vulnerable state because they already have very low populations in natural habitats (Badola & Pradhan 2010a,b). Additionally, the trees are deforested rapidly in many areas due to increasing human settlements, tourism influx and clearance for foot paths and these factors contribute to the depletion of rhododendrons from many natural habitats. The assessment of potentially rich areas for rhododendrons is one of the priorities for conservation management in protected areas. Therefore, the present study was carried out in the Khangchendzonga Biosphere Reserve (KBR; the core zone, Khangchendzonga National Park has recently been inscribed as world heritage site on 17 July 2016 by UNESCO) of Sikkim Himalaya. We identified the Kusong-Panch Pokhari transect of KBR in northern Sikkim as one of the unexplored landscapes to assess the extent of rhododendron diversity and also in offering potential environmental management strategies that can be employed within the transect.


Study area

The Kusong-Panch Pokhari transect falls in Khangchendzonga Biosphere Reserve (KBR). The KBR (27°15’-27°57’ N & 88°02’–88°40’ E; Fig. 1) covers 2913.12km2 spatial area (after inclusion of transition zone in 2010; Badola & Subba 2012) in Sikkim eastern Himalaya (India). The core zone of KBR, as the national park and a UNESCO world heritage site, has 1,784km2 area. The Kusong Village is the trailhead, surrounded by rich temperate forests forming a lush green valley, meandering streams, and waterfalls with snow-capped mountains in the backdrop of the picturesque landscape. The Lepcha community village has 37 households with a population of approximately 906 individuals. The villagers totally depend on cardamom cultivation for their economy; they also grow agricultural produce like potatoes, peas and maize as subsistence farming. Nowadays, local people expect tourism product-based economic benefits, particularly because they have been experiencing loss of cardamom cash crop due to disease infestation and subsequent insufficient production. Therefore, local people are looking forward to promoting an eco-tourism trek route, i.e., “Kusong to Panch Pokhari” with its unique glimpse into rhododendron diversity, numerous high altitude lakes and panoramic view of the Mt. Khangchendzonga (8,586m) along with other snow-capped mountains, offering a new vista for adventure tourism.

The first exploration was conducted during the Kusong-Panch Pokhari transect (Fig. 1; also a part of, hitherto seldom used, trekking corridor) extending approximately 25km along 1,500–3,800 m in KBR. It is a steep terrain extending to a small-extended plain in the slopes of the mountains. The landscape experiences cool temperate climate; tough rocky terrain maintaining high precipitation and a winter with heavy snow fall (so far no weather data available for the study transect). The Kusong-Panch Pokhari transect broadly has four forest types, viz.: warm broad leaved temperate forest, cold broad leaves / mixed conifer forest, subalpine and alpine scrub, and grasses.


From June to December 2016, we conducted two randomized systematic survey (following Pradhan & Badola 2008) in Kusong to Panch Pokhari vertical transect in KBR in Dzongu landscape (1,500–3,800 m). Plant species including rhododendrons were identified in the field, without disturbing the natural habitat. Besides authors’ earlier field experience in rhododendron collection, Hooker (1849), Pradhan & Lachungpa (1990), Polunin & Stainton (2006) and numerous photographs were used in identification. As the major study area falls in Khangchendzonga National Park, in the case where instant identification was a little difficult, photographs were taken to identify the species with the help of the herbarium of Botanical Survey of India, Gangtok. In addition, coordinates were recorded (latitude, longitude and altitude) with the help of a hand held GPS (Global Positioning System) at each point where any rhododendron population was encountered. We then modeled the distribution of Rhododendron spp. native and/or naturalized along the transect using ArcGIS Version 9.3 with Map Source Software (ESRI 2011) and Microsoft Excel (2010), and the quantified correlation between the present altitudinal range of Rhododendron species and their past altitudinal range available in the literature for the Sikkim Himalaya using Spearman Rho Test (SPSS Version 21).





Results and Discussion

Along the Kusong-Panch Pokhari transect in Khangchendzonga Biosphere Reserve (northern Sikkim), we recorded 23 species of rhododendrons (Fig. 1; Table 1), of which five are considered as eastern Himalayan endemics, viz.: Rhododendron grande, R. camelliiflorum, R. ciliatum, R. glaucophyllum and R. lanatum. Although the R. maddenii populations are reported as rare in Sikkim State (Badola & Pradhan 2010b), IUCN records these species under Data Deficient category. At low altitudes (2,300–2,800 m), we recorded the sparse populations of R. dalhousiae, R. falconeri, R. grande and R. arboreum, in association with Acer campbellii, Acer spp., Quercus spp., etc. Towards subalpine sites, the presence of R. fulgens makes the scene enchanting. On reaching rocky heights towards Panch Pokhari area, we observed small epiphytic shrubs of R. vaccinioides growing on other rhododendron species colonizing the southeastern-facing rocky outcrops. We encountered Rhododendron griffithianum as the dominant and most widespread species in the valley, ascending from 3,010–3,446 m. We correlated the present altitudinal range of the species in the study site with their historical altitudinal range and found a positive correlation between them (r=0.749, at the significant level >0.05, Spearman’s rho). Amongst identified species, 10 are considered threatened locally (Table 1; Pradhan & Lachungpa 1990; Mao et al. 2002; Mao 2010), viz.: R. triflorum, R. campanulatum subsp. aeruginosum, R. falconeri, R. grande, R. campylocarpum, R. edgeworthii, R. lepidotum, R. ciliatum, R. cinnabarinum and R. anthopogon. The sparse populations of R. lanatum, R. fulgens and R. maddenii may be threatened in the future in the Sikkim Himalaya. Some of these species need immediate conservation attention for their long-term survival. The historical records of altitudinal distribution of the Rhododendron species of the Sikkim Himalaya show that a few species have been shifting their altitudinal range as per our present observations. It could be one of the reasons many Rhododendron species of eastern Himalaya are very sensitive to climatic changes (Mao 2010; Badola 2010; Gaira et al. 2014). It is reported that the eastern Himalaya have been experiencing a slightly increasing mean annual temperature (IPCC 2014). Consequently, many species of warm temperate forests have become dominant over the cold temperate forest communities (Beaugrand et al. 2002). In the entire transect, we found only two small populations of R. maddenii at 3,183–3,010 m growing under Abies densa, experiencing habitat loss due to encroachment by R. griffithianum (Gibbs et al. 2011). We observed a steady change in Rhododendron species from 2,800m onwards, as a very distinct feature from this altitude zone (Acharya et al. 2011). For being very steep, rocky type, this transect is one of the best habitats for rhododendrons. The transect manifested a sign of fuel wood collection and lopping of timber in the lower zone around 1,500–2,500 m and other anthropogenic pressures also in the lower zone. The sign of natural calamities like avalanches and landslides are common at a few places along the higher zone. These activities may be detrimental to rhododendron diversity and populations in Sikkim Himalaya.

The 23 recorded Rhododendron species along Kusong-Panch Pokhari transect comprised large trees (02 species), shrubs or small trees (06 species), epiphytic shrubs (04 species) and shrubs (11 species). Amongst them, R. griffithianum has been observed as the most dominant taxa followed by other species such as R. grande, R. hodgsonii, R. campanulatum R. thomsonii; however, these stands transitioned into Abies densa communities closer to the timberline at 3,600m. In Sikkim, 37 rhododendrons species (with several sub-species and varieties) occur along 1,500–6,000 m gradient (Pradhan & Lachungpa 1990; Mao 2010; Badola & Pradhan 2010a). In our study transect, the highest diversity (15 species) of rhododendrons occurred between 3,100–3,700 m, whereas, the lower elevation (2,300–2,800 m) recorded with only two species.

In Kusong-Panch Pokhari transect, we encountered many other floral elements, including important high-value medicinal plants such as Aconitum spp., Rheum spp., Picrorhiza kurrooa, Cordyceps sinensis, and so on. The faunal elements like Himalayan Black Bear Ursus thibetanus, Himalayan Thar Hemitragus jemlahicus, Blood Pheasant Ithaginis cruentus, Himalayan Goral Naemorhedus goral, Barking Deer Muntiacus vaginalis, Satyr Tragopan Tragopan satyra, Kalij Pheasant Lophura leucomelanos, Common Leopard Panthera pardus, Red Junglefowl Gallus gallus, Red Panda Ailurus fulgens, Himalayan Monal Lophophorus impejanus and so on (Table 2) are found along the transect. Our local Lepcha guide and many villagers informed us that the Musk Deer and Red Panda populations in the studied landscape are stable, although further research into the validity of these perceptions is suggested. Although, all the 23 species recorded and identified in our survey are also reported from other areas of northeastern India, the size and status of these populations are yet to be assessed (Paul et al. 2005; Badola & Pradhan 2010a,b). This is the first time Kusong-Panch Pokahri transect in northern Sikkim was explored. The trail, which falls within KBR in northern Sikkim, is one of the potential repositories of biodiversity of Sikkim including diverse rhododendrons as well as faunal species for future conservation studies. The increasing human population and various anthropogenic activities through direct and indirect ways, along with natural calamities will cause habitat degradation. Like other Himalayan parts (Mao et al. 2001), at present Sikkim Himalayan rhododendrons and their habitats face significant threats from both changing climate and increased anthropogenic pressures (Badola 2010; Chettri 2015). In the past, illegal grazing and fuel wood extraction have led to the decline and degradation of many old growth forests in Sikkim Himalaya. As grazing has been banned in Sikkim since 1998, these adverse factors, viz., forest loss, gradual land-use changes and exploitation of forest resources, continue to put pressure on the resilience of rhododendron forests in Sikkim (Menon et al. 2012). Natural causes of Rhododendron forest decline include landslides; avalanche and wild fires, which eradicate smaller patches of forest. In Sikkim, high density rhododendron areas fall on trekking corridors, which are susceptible to disturbances (Chettri 2015). But, for its aesthetic beauty and the rich rhododendron diversity and the panoramic view of Mt. Khangchendzonga, the third highest peak in the world, along with many snow-capped mountains, the Kusong-Panch Pokhari transect could be an emerging and potential trekking destination. Caution must be taken when developing the Kusong-Panch Pokhari transect as a tourist corridor. Case studies suggest that promoting eco-tourism targeting high altitudes and wilderness should be more strategic from the long-term conservation perspective, in spite of its potential value in enhancing local economies. Moreover, similar environments along the Yuksom-Dzongri transect (west Sikkim) trekking corridor have shown continued pressures on biodiversity (Chettri 2015), as the tourist flow increases at a rapid rate each year, therefore, care must be taken by creating awareness and outreach to local communities, owners of home stays and guides on the value of biodiversity.




















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