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Vol. 8(10), pp. 15-20The McAllen International Orchid Society JournalOctober 2007

Peer-Reviewed Article
Effective Publication Date : 7-Oct-2007

Habenaria intermedia D. Don - an Endangered Medicinal Orchid

R. S. Chauhan*, M. C. Nautiyal, and P. Prasad

High Altitude Plant Physiology Research Centre, HNB Garhwal University, Srinagar (Garhwal) 246 174, Uttarakhand, India
*Present address: Division of Biodiversity and Applied Botany, Indian Institute of Integrative Medicine (CSIR), Canal Road, Jammu 180 001
E-mail: rchauhanua@gmail.com

Key Words:  endangered species (EN), percentage frequency (%F), density (D, plant m2), total basal cover (TBC, cm2m2), Importance Value Index (IVI).

Introduction

The Western Himalaya is one of the well-defined and better-known phyto-geographical regions of the Indian subcontinent. It is extremely rich in plant life and abounds in diversity of medicinal and aromatic plants (Rao 1994). Many such species are at the verge of extinction due to evolutionary trends or man made threats, of which latter is predominant factor during past few decades. Habenaria is a large and an important genus of family Orchidaceae, distributed in tropical to temperate regions of the world. The genus Habenaria is represented by approximately 500 species, of which eight species have been reported from India. H. intermedia and H. pubescens are medicinally important among them. H. intermedia is rapidly disappearing due to indiscriminate digging for their edible tubers. During our study we could not find any specimens of H. pubescens from earlier reported places, whereas, H. intermedia was available in small patches in different regions of the Western Himalaya.

H. intermedia is known as 'Riddhi' in ayurveda and distributed in grassy slopes between 2000-3000 m in Himalayan region. The tubers of this species are known for its medicinal use, as it forms an important constituent of many medicines in ISM (Indian System of Medicine), health tonic, astverga group (a combination of 8 rejuvenating drugs), and in preparation of the ayurvedic tonic 'Chyawanprash'. Tender leaves as well as tubers are edible and cooked as vegetables. Mature tubers are also useful to prepare salep. The domestic annual demand (in study area) of H. intermedia was 99.9 kg in 2001-02 and estimated to increased to 995.5 kg during year 2004-05, while the supply is decreasing gradually (Ahuja 2003). To fulfill market demand, tubers were collected indiscriminately with destructive harvesting systems that reduced their abundance in natural populations. The rarity of the species can be justified on the basis of their extant populations in nature.

IUCN categorized it as an endangered species (EN). Quantitative data are still lacking and survey is recommended to collect such information, whereas a steady decline (50-80%) was felt in population size of the species during last ten years (Ved et al. 2003). The abundance of many orchid species is believed to have fallen to critical levels in recent years (Kull et al. 2006). Demographic studies are essential for better understanding of the relationship between natural dependent plants and the community in which they are found (Zotz and Schmidt 2006). The species is medicinally important and endangered whereas basic information is lacking to initiate a conservation program. Clearly, detailed information on orchid population biology is needed to assist conservationists in developing appropriate management plan (Zotz and Schmidt 2006). The species is facing a threat of survival, so it is important to study population biology and threats for effective conservation. This paper presents the phytosociological behaviour of the species among different natural populations in the western Himalayan region. This study will be helpful to understand ecological complexity of not only H. intermedia but also other threatened orchid species.

Material and methods

Present studies were undertaken in six different natural populations of the western Himalayas (Uttarakhand), India (29°26'-31°28' N and 77°49'-80°6' E). The detail description of each study site is given (Table 1). Frequent visits to selected areas were carried out during the active growth seasons of 2004-2006.

Table 1. Site characteristics of the selected populations of Habenaria intermedia.

Collection SiteCodeAspectAltitude (msl)Dominant associated species
ChoptaCHNW2700Anaphalis sps. Quercus sps.
GhimtoliGHSW2000Anaphalis sps. Quercus sps.
MadhyamaheshwerMDNE2500Polygonum sps. Quercus sps.
MussooriMSNE2200Danthonia sps. Anaphalis sps.
RambaraRMSW2700Anaphalis sps. Polygonum sps.
RudranathRNSE3000Anaphalis sps. Geranium sps.

NE-northeast; SE-southeast; SW-southwest; NW-northwest

A general survey was carried out to get a picture of entire study area and occurrence of species. For phytosociological analysis, areas of 100 m2 in the area of occurrence of species were identified and marked on each site. Vegetation sampling was conducted through vertical belt transacts method (Michel 1990). Ten quadrats of 1m2 size were laid randomly in sampling area. Individuals of all species associated with H. intermedia were counted. Analytical features for population study such as percentage frequency (%F), density (D, plant m2) and total basal cover (TBC, cm2m2) was calculated (Mishra, 1968). Distribution pattern was analyzed on the basis of abundance (Kershaw 1973).

Results and discussion

Fig. 1. Flowerng plant, Habenaria intermedia (author photo).

Fig. 2. Habenaria intermedia, developmental stages (author photo).

The plants grows at an altitude of 2000-3000 m in sunny as well as partial shady grassy slopes in sandy loam to clay, soil (pH 6.5) with proper water drainage. Such habitat has rocky grassy slopes with very few woody plants and range of the distribution was also very narrow in all populations. Species start emerging with the increase in temperature during the month of March and complete one phenophase (reproductive (Fig. 1) or vegetative (Fig. 2) of lifecycle until September. During the months of September-October, yellowing of aerial parts indicate sign of senescence in natural habitat. Aerial parts of the plants dry up while underground tubers enter into dormant phase until the return of favourable conditions in the next growing season (summer months).

Phytosociological data (Table 2, following page) reveals that the species is distributed randomly in Chopta, Ghimtoli and Mussoorie, whereas regular in three other populations based on the A/F ratio. Density of H. intermedia was very low (1.4-3.4 plant m2), whereas frequency of distribution was between 60-80% among studied population. The Total Basal Cover (TBC) of species was almost similar (between 1.02-2.89) among studied populations. Relative dominance of species was much lower in Rambara and Madhyamaheshwer as compared to other populations. The Importance Value Index (IVI) of species was recorded between 13.72-35.99 among studied populations. Common dominant species associated with H. intermedia in studied populations were Anaphalis sps., Danthonia sps., Polygonum sps., Quercus sps. and Geranium wallichianum.

Table 2. Percentage frequency, density (plant m2) and IVI of different populations of Habenaria intermedia.

PopulationAbundanceFrequency (%)A/FDensity (plant m2)TBC cm2 m2Relative dominanceIVI
CH2.0600.031.21.0217.8829.10
GH4.3800.053.42.8917.5429.26
MD1.2600.021.51.152.2518.15
MS2.6800.032.11.7822.6135.99
RM1.8800.021.41.163.9513.72
RN1,9800.021.51.2414.8528.09

Seeds are microscopic, yellowish-white powdery mass. Similar to other terrestrial orchids, reproduction through seed germination is very poor (less than 5%) even after good seed viability (> 80% at the time of seed dispersal) and seeds germinate only in a natural habitat. Poor seed germination (less than 1%) was also reported in terrestrial orchid species Caledenia arenicola (Batty et. al. 2001). Phytosociological analysis revealed that open sunny meadows with moderate slopes are the preferred habitat for this species. Low density of H. intermedia among studied populations may be due heavy exploitation for medicinal purpose, poor regeneration, low seed germination and seedling establishment, habitat loss, grazing, forest fires, competition with other dominant species of community. Heavy harvesting pressure is a major threat among other factors for reduction of population size. The government has imposed a ban on collection of a majority of threatened species but it has failed to check illegal exploitation. Orchids are subject to a high level of threat, through both natural and anthropogenic causes (Kull et al., 2006). Due to man-induced changes in the form of over and illegal exploitation of plants in the area of high conservation value, centre of endemism and species diversity, the original habitat became fragmented into isolated patches leading to fragmentation of species population as in case of the Himalayas (Tandon 1998). The random pattern of distribution indicates that the species grows in local colonies and is found in a specific niches. A random and regular type of distribution pattern is common characteristic of species rich communities (Rikhari et al. 1993). Low IVI in Rambara and Madhyamaheshwer show that species is facing competition with other associated species as compared to other populations. A few associated species i.e. Danthonia cachemyriana, Anaphalis nepalensis, Polygonum sps., Geranium wallichianum etc. attain larger size than H. intermedia and become competitor for light, moisture, minerals etc. Competition by such associated species may be one reason for low regeneration potential. One might expect the abundance data to be superior under all circumstance because more information is collected at each site (Lina et al. 2006). The phenotypic variation in plants may be due to particular ecological niche, soil moisture, altitude, slope and microenvironment of different populations.

Although the species is listed as endangered, there is no management plan for conservation due to the lack of related information. Collection of this species continues from the wild through illegal means. Illegal and destructive harvesting was also reported earlier for a few other medicinal plants in the study area (Chauhan 2004; Kala 2005). Domestication and cultivation of such endangered medicinal orchids may be encouraged to fulfill market demand, which will increase the income of local people on one hand and reduce pressure on the natural habitat on the other. It is pertinent to point out that sale of medicinal herbs generates more income than the traditional crops in Uttarakhand (Silori and Badola 2000).

The germplasm collected from all studied populations is currently under observation for phenotypic and genotypic variation in similar environmental regimes in Pothivasa (2200 m) and Tungnath (3600 m) nurseries. It can be concluded that priority should be given for the restoration of such species to protect them in natural habitat. Such economically endangered medicinal orchid should be conserved with both in situ and ex situ methods of conservation in natural habitat on one hand and domestication and cultivation to meet market demand on other. Further study may be initiated to increase seed germination, seedling establishment and detail the ecological adaptation of this species to strengthen a conservation program.

Acknowledgements

The authors are grateful to Prof. A. R. Nautiyal, Director, HAPPRC for providing facilities and encouragement. They are also thankful to Dr. B. P. Nautiyal, Dr. H. C. Purohit and field staff for their help during this work. Financial support from Dept. Of Biotechnology, Govt. of India, New Delhi is gratefully acknowledged.

References

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Copyright © 2007 R. S. Chauhan*, M. C. Nautiyal, and P. Prasad