Introduction

Chamba district of Himachal Pradesh is considered as one of the richest area of traditional and potential medicinal wealth. The district is bounded by Kangra district of Himachal Pradesh and Gurdaspur district in the south of Punjab, Jammu and Kashmir in the north and Lahaul Spiti in the west. The district has two tribal regions, viz., Pangi and Bharmour. Bharmour is situated in the west of this district, whereas Pangi Valley is situated in the north. The vegetation of the district Chamba varies considerably, chiefly owing to elevation and rainfall variations.

The unprecedented rate of species extinction in recent times projects about quarter of the global species to be lost or threatened by the middle of 21^st century (Raven, 1990). With growing global concern for species endangerment, especially over the past two decades, the term biodiversity has encouraged conservationists to look for causes and consequences of species extinction and finding ways for their conservation. Human activities and unsustainable harvesting in the wild have been identified as one of the biggest causes of reported phenomenal loss of species (Lewin, 1986; Wilson, 1988). The recent IUCN Red List sampled 91% plant species as threatened due to habitat loss and degradation (Hilton, 2000). India is ranked at sixth place for having the largest number of threatened plant species in the above IUCN Red List. It is well understood to extinction and by understanding the processes that contribute to their rarity, future loss of diversity may be deferred or reduced (Flather et al.,1994).

With growing awareness of the people towards the use of herbal medicine during mid 1980s to the 1990s, about 233 major pharmaceutical companies globally became involved in screening of plants for new leads (Aryal, 1993). Nearly 2,500 wild plant species are reported in use for medicinal purpose in Indian subcontinent, of which, possibly about 300 taxa are used in 8,000 licensed pharmaceuticals in India (Ahmad, 1993). In recent years, India has emerged as one of the biggest suppliers of raw material (Holley and Cherla, 1998) ranking second amongst 12 world leading exporter countries (Lange, 1997). Collection of medicinal herbs as Minor Forest Produce (MFP) under forest law as traditional rights in designated forest land (Anderson, 1886) has been an important source of the native’s income in Himachal Himalaya (Dobriyal et al.,1997; Tandon, 1997; Badola, 1998, 2002).

A rough estimate and secondary sources suggest availability of about 1,000 to 1,200 medicinal plant species in Himachal Himalayas (Gupta, 1964, 1971; Gaur and Singh, 1993; Chauhan, 1999; Badola, 2001). As per the habitat type, these share 18% trees, 21% shrubs, 55% herbs in composition, which coincides more or less with that of Indian Himalayan Region, having 23%, 22% and 58% species of trees, shrubs and herbs, respectively (Samant et al.,1998).

Kumar et al. (2010) carried out a study of ecological status of ethno medicinal plants in the Garhwal Himalaya. The northern part of India harbours a great diversity of medicinal plants due to its distinct geography and ecological marginal conditions. They reported total of 57 species, including 14 trees, 10 shrubs and 33 herbs. Regular and random distribution pattern of species reflect the higher biotic pressure in terms of grazing and lopping in natural forest stands (Kumar et al., 2010). Shameem and Kangroo (2011) carried out a study in Dachigam National Park, Kashmir Himalaya, India reported that most of the species in their study were distributed contagiously. The studies carried out by Shadangi and Nath (2005) also gave similar findings of contagious distribution pattern of species.

In Study area, it has been reported that a number of species like Angelica gluaca, Picrorhiza kurroo, Jurinea dolomiaea and Podophyllum hexandrum are under the threat of extension (Dinanath, 2007). This calls upon the taxonomists and economic botanists to undertake systematic studies on the existing flora to identify and inventoried the medicinal and aromatic plant species enabling the scientists, planners and administrators to initiate effective steps for their conservation and sustainable utilization, otherwise the area may lose some of these species forever. Furthermore, tribal people residing in the study area, since thousands of years have been interacting with the flora and have evolved their own traditional healing methods, relying heavily on local medicinal plant resources (Karki and Willians, 1999). There is no proper record available regarding the community composition and distribution of the medicinal plant diversity of Holi area. Keeping these factors in view, the present study was carried out with the objective to study community composition and distribution pattern of herbaceous flora.

Materials and Methods

The present study was carried out in Holi Forest Range of district Chamba, which is located between latitude 32^o17’412’’ to 32^o26’541’’ N and longitude 76^o31’504’’ to 76^o35’385’’E. Extensive field survey of the selected areas of Holi starting from the lower elevation at Deol (2,300-2800 m), Kut (2,800-3300 m), Dal (3,300-3800 m) and Lahaud Dhar (3,800 m and above) under Holi Forest Range was carried out (Table 1 and Figure 1).

Table 1: Location of study sites

Figure 1: Sites of study area (Holi)

For the vegetation analysis of herbaceous layer, a total of 160 plots of 1x1 m size quadrate laid out randomly in the study area. Species richness was simply taken as a count of number of species present in that forest type. The vegetation data were quantitatively analyzed for density, frequency and abundance (Curtis and McIntosh, 1950). Importance Value Index (IVI) was calculated using the sum of relative frequency, relative density and relative dominance (Phillips, 1959). The quantitative analysis for different parameters was calculated as follows:

Frequency (%)

Frequency indicates the number of sampling units in which a given species occur. Percent frequency was calculated as follows:

Frequency (%)=(No. of sampling units in which species occurred÷Total number of sampling units studied)×100

Density  

It represents the numerical strength of species in a community. Density was calculated as follows:

Density= (Total number of indivuduals of a species in all sampling units÷Total number os sampling units studies)×100

Abundance

Abundance is analyzed to get an idea of distribution pattern of the species.

Abundance=(Total number of individuals of a species in all sampling units÷Total number of sampling units in which species occurred)

Basal area

Basal area is the area of ground actually penetrated by the stems, and is readily seen when the leaves and stems are clipped at the ground surface. Basal area of herbs was measured at the ground level which is calculated as:

Basal area=πr²

Importance value Index (IVI)

The IVI which is an integrated measure of the relative frequency, relative density and relative basal area, was calculated from the basic data for each species of herbs (Phillips, 1959) as:

Importance value index=Relative frequency+relative density+relative dominance

The relative values of frequency, density and basal area was calculated as follows:

Relative frequency=(Frequency of individual speices÷Frequency of all speices)×100

Relative density=(Density of individual speices÷Density of all speices)×100

Relative dominance=(Basal area of individual speices÷Basal area of all speices)×100

Abundance to frequency ratio

Abundance to Frequency ratio (A/F ratio) for different species was determined for eliciting the distribution pattern. The distribution pattern of species is considered regular if ratio is <0.025, random if ratio between 0.025-0.05 and contagious if ratio >0.05 (Curtis and Cottam, 1956; Whitford, 1949) as:

A/F ratio = Abundance÷Frequency

Results and Discussion

Frequency, density, basal area and importance value index of plant species at Deol are presented in Table 2.

Table 2: Frequency, density, basal area and importance value index of plant species at Deol

Table 2: Continue...

It has been observed that Diplazium esculantum has the highest frequency (70%) closely followed by Lecanthus peduncularis and Morchella esculenta (60% each) whereas, Ainsliaea aptera has the lowest frequency (10%). Nasturtium officinale has the highest density (10.0 plants m^-2) followed by Fagopyrum esculentum (6.2 plants m^-2) whereas, Ainsliaea aptera has the lowest density (0.2 plants m^-2). Verbascum cylindericum was found to have highest basal area (0.622 cm²) followed by Artemisia vulgaris (0.520 cm²) whereas, Chrysopogon gryllus and Cynodon dactylon has the lowest basal area (0.002 cm²). Morchella esculenta has the highest value of IVI (16.58) followed by Diplazium esculantum (13.77) whereas, Ainsliaea aptera has the lowest value of IVI (0.85). Thus, depicting that Morchella esculenta was the dominant species, Diplazium esculantum codominant and Ainsliaea aptera the associated species. At Deol, the highest numbers of species were distributed randomly followed by contagious pattern of distribution and lowest species were distributed regularly.

Frequency, density, basal area and importance value index at Kut, are shown in Table 3.

Table 3: Frequency, density, basal area and importance value index of plant species at Kut

Table 3: Continue...

Viola serpens was found to have highest frequency (70%) closely followed by Valeriana jatamensii (60%) whereas, Artica parviflora has the lowest frequency (10%). Viola serpens was found to have highest density (85.5 plants m^-2) followed by Valeriana jatamensii (5.8 plants m^-2) whereas, Artica parviflora has the lowest density (0.5 plants m^-2). Moschela esculenta was found to have highest basal area (1.234 cm²) followed by Gentiana karrooa (0.656 cm²) whereas, Agrostis species has the lowest basal area (0.002 cm²). Viola serpens was the dominant species with highest value of IVI (78.77) followed by Morchella esculenta (34.58) as the codominant and Artica parviflora the associated species with IVI value of 1.49. At Kut, the distribution pattern of most species was reported random followed by contagious and least species were distributed contagiously.

Frequency, density, basal area and importance value index at Dal, are shown in Table 4.

Table 4: Frequency, density, basal area and importance value index at Dal

Poa alpina was found to have highest frequency (90%) closely followed by Jurinea dolomiaea (80%). Poa alpina was found to have highest density (60.6 plants m^-2) followed by Poa annua (35.5 plants m^-2) whereas, Saussurea taraxacifolia has the lowest density (0.6 plants m^-2). Jurinea dolomiaea has the highest basal area (0.485 cm²) followed by Rheum moorcroftiasana (0.366 cm²) whereas, Poa alpina has the lowest basal area (0.004 cm²). Poa alpina has the highest value of IVI (65.91) followed by Poa annua (42.14) whereas, Buplerium falcatum has the lowest value of IVI (2.87). This depicts that Poa alpina was the dominant species, Poa annua codominant and Buplerium falcatum the associated species. At Dal, contagious distribution pattern of species was dominant followed by random pattern of distribution and none of the species was reported for regular distribution pattern.

Frequency, density, basal area and importance value index at Lahaud Dhar, are shown in Table 5.

Table 5: Frequency, density, basal area and importance value index at Lahaud Dhar

Jurinea dolomiaea was found to have highest frequency (70%) followed by Gentiana kurrooa (50%) whereas, Podophyllum hexandrum has the lowest frequency (10%). Gentiana kurrooa has the highest density (35.8 plants m^-2) followed by Jurinea dolomiaea (26.6 plants m^-2) whereas, Euphorbia cognate has the lowest density (0.5 plants m^-2). Saussurea gossypiphora has the highest basal area (0.542 cm²) closely followed by Jurinea dolomiaea (0.541 cm²). Gentiana kurrooa has the highest value of IVI (65.37) closely followed by Jurinea dolomiaea (65.36) whereas, Pleurospermum brunonis has the lowest value of IVI (5.54). It depicts that Gentiana kurrooa was the dominant species, Jurinea dolomiaea codominant and Pleurospermum brunonis the associated species. At Lahaud Dhar, the most of the species were distributed randomly followed by contagious pattern of distribution and the least species were reported for regular distribution pattern.

Conclusion

Maximum species (60) were reported from Deol area and minimum (17) from Lahaud Dhar. It has been observed that Poa alpina has the highest frequency (90%), highest density (60.6 plants m^-2) at Dal. Gentiana kurrooa has the highest density (35.8 plants m^-2) at Lahaud Dhar. Moschela esculenta has the highest basal area (1.234 cm²) at Kut. Viola serpens was the dominant species with highest value of IVI (78.77) closely followed by Poa alpine (65.91), Gentiana kurrooa (65.37) and Jurinea dolomiaea (65.36). Most of the species were distributed randomly followed by contagious pattern of distribution and least number of species were reported showing regular distribution pattern.

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