The Orchid Diversity in Sikkim

 
  INTRODUCTION  
 

Sikkim is the smallest state of the Indian Union yet it surpasses other states of India in having maximum orchid diversity trailing just behind Arunachal Pradesh which has the highest number of orchid species. But if the biodiversity ratio of orchid species to land mass is considered then Sikkim stands the highest perhaps even in the world. Arunachal Pradesh whose geographical area is more than eleven times that of Sikkim has only 620 orchid species and Bhutan whose geographical region is six times the size of Sikkim has only 372 orchid species as compared to Sikkim?s 523.

 
     
  Why North-East India has more orchid diversity than Tropical Rain Forest?  
 

According to J.Joseph the author of Orchids of Nilgiris, North East India forms the junction of immigratory elements from the neighboring regions like Tibet, China Burma and other regions. Another reason given is that the region falls in the tremor belt and according to the tremor theory (Joseph 1982) the electromagnetic and other forms of invisible energies, released by the occasional tremors, bombard the genome, effecting large scale natural mutation which ultimately leads to speciation. The theory seems to hold good when comparing North East India to South India, having humid Tropical and subtropical rainforest climate conducive for prolific production of epiphytic orchids. But if we compare orchid diversity among the States of North East India, we find Sikkim stands the second highest in orchid diversity next only to Arunachal Pradesh. According to the Tremor theory the State of Meghalaya should be having the maximum number of orchid species since the state is situated on the active tremor zone, but it is not so in reality.

 
     
 

The State Sikkim has only 7096 sq.km geographical area but has an unique geographical feature. The State is a rectangular piece of land which is 64 to 96 km long and 160 km broad. It is a totally land locked area and is squeezed in between two Himalayan kingdoms-the Kingdom of Nepal in the West and Bhutan in the East. It lies between lat. 27? 5? and 28? 9? N. and long. 87? 59? and 88? 56? E. A part of the southern boundary of Tibetan Plateau butts in right inside the whole northern boundary of Sikkim thus rendering the climate similar similar to that of cold desert. The horizontal Dongkya range and other ranges in its southern part form a formidable barrier arresting the monsoon rain from passing through thus making its leeward side dry and cold. Whereas the windward side on the southern part of the Dongkya range receives the maximum monsoon rain and thus give the area the wet alpine type of climate. The general trend of mountain ranges in Sikkim is from east to west-Mt Pandim (6691m), Mt Simvo (6811m), Mt Siniolchu (6887m), Mt Kabru (7338m) and Mt Narsing(5825m), but there are two main long south north directed ridges running parallel to each other 64 to 96 km apart. The Singalila range which is about 64 km long, almost starts from plains level, separates Sikkim from Nepal in the West and culminates near its northern extremity in world?s third highest mountain, the Mt Khanchendzonga (8598m). The Chlola range in the East in comparision is much higher in elevation and it separates Sikkim from Bhutan in the East. Besides that there is the deep Chumby valley separating Sikkim and Bhutan. In general the valleys are narrow at the top and broader at the base. But in Sikkim valleys are broad at the top. Broad valleys like Donkong, Gyamchona, Cholamu and Muguthang are stretches of plain areas with unique faunal and floral diversity similar to that of Tibetan plateau and worth seeing.

 
     
 

The Singalila Range on the west, the Chola on the east with Tibetan Plateau in the north virtually enclose Sikkim in a titanic horseshoe. There is an another central longitudinal spur which separates the great Teesta catchment in the East from the great Rangit catchment in the west, culminating at Moinam Peak (3234m). Besides these major mountain ranges the state is criss-crossed with variously and oddly directed mountainous terrains having their own mini-microshade catchment areas thus providing many different types of micro-climatic niches congenial for species speciation. The diverse aspect classification also supports the view. As we proceed from the gentle southern slopy mountainous region towards north, the mountain ridges become steeper and sharper. Besides that there is a wide range of altitudinal variation starting from 460 ? 8598 m. The major climatic zonations in Sikkim are Tropical, Sub-Tropical, Sub-Temperate, Temperate, Dry-Alpine and Wet-Alpine. Through deep valleys the hot and moist Tropical climate penetrates right into the heart of Sikkim State, providing hotter southern and cooler northern slopes. As such the famous Teesta valley Sal penetrates right upto the sothern slopes of Dickhu valley in the East Sikkim and Tikjek and Tharpu valleys in the West Sikkim.These unique geographical features having wide range of altitudinal zonations, rich humidity percentage in the air and the high range of prcipitations, makes the Sikkim state, pockets of many microclimatic niches, harbouring rich flora and faunal diversity differing from one valley to another.

 
     
  Table 2. Endemic orchids of Sikkim and their altitudinal distribution.  
 
SI No.  Species Habitat Altitudinal Range
1. Bulbophyllum trichocephalum var.capitatum S.Z. Lucksom Lithophytic 800 ? 1000 m
2. Calanthe anjanii S.Z.Lucksom Terrestrial 2000 ? 2500 m
3. Calanthe keshabii S.Z.Lucksom Terrestrial 2000 ? 2600 m
4. Calanthe yuksomnensis S.Z.Lucksom Terrestrial 1000 ? 2700 m
5. Coelogyne pantlingii S.Z. Lucksom Epiphyte 2100 ? 2500 m
6. Coelogyne treutleri Hook. f. Epiphyte Tropical valley
7. Cremastra appediculata var. sonamii S.Z.Lucksom Terrestrial 920 ? 1000 m
8. Crepidium saprophytum (King & Pantling) A. Nageswara Rao Terrestrial 1200 m.
9. Cymbidium whiteae King & Pantling Epiphyte 800 ? 2000 m
10. Dendrobium eriiflorum var. Sikkimensis S.Z. Lucksom Epiphyte 800 ? 1000 m
11. Didicia cunninghamii King & Prainex King & Pantling Terrestrial 4000 m
12. Goodyera dongchenii S.Z.Lucksom Epiphyte  2000 ? 2300 m
13. Gastrochilus sonamii S.Z.Lucksom Epiphyte 2300 - 2700 m
14. Listera alternifolia King & Pantling Terrestrial 3000 ? 3500 m
15. Liparis chungthangnensis S.Z.Lucksom Lithophyte 1800 ? 2000 m
16. Liparis dongchenii S.Z.Lucksom Terrestrial 1500 ? 2000 m
17. Liparis lydiaii S.Z.Lucksom Epiphyte 1000 ? 1300 m
18. Liparis pygmaea King & Pantling Lithophyte 4350 m
19. Malaxis saprophyta (King & Pantling) T. Tang & F.T.Wang Terrestrial 1800 m
20. Oberonia kingii S.Z. Lucksom Epiphyte 1000 m
21. Pantlingia paradoxa Prain Terrestrial 2000 m
22. Peristylus pseudophrys ( King & Pantling) Kranzlin Terrestrial 1800 m
 
     
  HISTORY OF ORCHIDS IN SIKKIM AND PRESENT STATUS  
 

King & Pantling who carried out the total orchid survey in Sikkim during 1898, have produced a well documented book ? The Orchids of Sikkim Himalaya? which has recorded 450 species of orchid species from Sikkim. Now after a gap of almost hundred years I have carried out my orchid studies starting from 1986, within the present political boundary of Sikkim. In two decades, this study has added , 12 new species, 4 sub-species, and 6 new reports with a few discoveries to the orchid history of Sikkim. Now Sikkim has more than 523 species spread over 134 genera. The orchid diversity in Sikkim is so diverse and rich that its total number of species is yet to be assessed properly and this study does not claim to have surveyed and sampled all the forest and woodland areas of Sikkim. There are still good chunks of virgin lands in Sikkim yet to be explored to unfurl the richness of its biodiversity.

 
 

 
     
  TABLE: 3. GENERAL DISTRIBUTION OF ORCHID SPECIES IN SIKKIM.  
     
 
Climatic Zonation Altitudinal Zonation Number of orchid species
Tropical Forest Upto 1000m 80
Sub-Tropical Forest Between 1000 ? 1500m 240
Temperate Forest Between 1500 ? 3500m  170
Alpine grassland Scrub Between 3500 - 4500m  33
Total   523
 
     
  Conclusion  
 

Most of the Sikkim orchids are beautiful but short lived. But there are species like Cymbidium eburneum, C. hookerianum and C, irridioides which were under exploitation since time immemorial and have been the mother plants of todays modern Cymbidium hybrids. As we are well aware of fact that the orchids of Sikkim though insignificant it may look like but are still being smuggled out of Sikkim indiscriminately under the very nose of strict vigilance. It means that somewhere else in the world (technically advance countries) these insignificant orchids are being used to produce beautiful orchid hybrids. So it is high time that one should realize the importance of our rich orchis diversity and act sensibly, giving due thought over increasing the technology knowhow by sending the promising individuals even to foreign countries to excel in the art of hybridization. On the other hand it is also felt dire need to improvise our strategies to stop our precious orchids species from being smuggled out of the State.

 
     
  BY:  
     
 

S.Z. Lucksom,
Director Himalayan Zoological Park, RVP & EPC,
Department of Forest, Env and Wildlife, Management, Government of Sikkim.