Phytosociological features and threat categorization of A . heterophyllum Wall . ex Royle and A . ferox Wall . ex Ser . in Kumaun Himalaya

Alpine and subalpine regions of Kumaun Himalaya were surveyed qualitatively and quantitatively for the population study to determine the status of Aconitum ferox and A. heterophyllum. Low population density across the surveyed populations and restricted distribution to specific pockets indicates poor availability of the species in the study area. Illegal and over exploitation of these species pose threat to their existence. The present study clarifies the population structure of identified aconite species in Kumaun Himalaya. Observations reveal that on the basis of six attributes (that is habitat preference, distribution range, population size, use pattern, extraction trend, native and endemic species) used to assign threat categories, both the Aconitum species are endangered.


INTRODUCTION
Since time immemorial, Himalaya is famous for its rich plant biodiversity including a wide range of medicinal and aromatic plants.The variety of soils, topography and climatic conditions of the region provide very congenial conditions for growth and development of many therapeutically important medicinal plant species (Rawat, 2005).However, most of these MAPs are experiencing habitat destruction due to unscientific, over and irregular exploitation of plants, which resulted in very fast depletion as well as extinction of some medicinally important plant species (Rau, 1975).There are many species which have become threatened in several tracts and are found only in inaccessible hilly areas.Recently, CAMP (2003) assessed threat status of plant species in Uttarakhand in which Aconitum ferox Wall.ex Ser. and Aconitum heterophyllum Wall.ex Royle were assigned the critically endangered and vulnerable status respectively.Aconites are widely recognized for their medicinal importance in Indian System of Medicine (ISM).According to Red List Categories published by IUCN (1993), threatened species are having small geographic area, narrow habitat specificity, commonly sparse and geographically restricted to special habitat.
A. ferox (Vern.Meetha-Vish, Vatsanabh) (Plate 1) and A. heterophyllum (Vern.Atees) (Plate 2) belongs to the family Ranunculaceae. A. ferox is an erect herb with glabrescent stem and long, broadly ovate, cordate leaves.Distribution of this species is found between 3000 -3600 ma.s.l. in Kumaun Himalaya (Figure 1).Tubers of the species are collected in the month of September-October and are used as remedy for stomach ache, fever, and indigestion by the aboriginals.A. heterophyllum (Vern.Atees) is an erect, tuberous herb found at the same elevation of A. ferox (Figure 1).Tubers are collected and dried during September-October and are used in diseases like diarrhea, fever, general body *Corresponding author.E-mail: l_tewari@rediffmail.com.ache and also used as an aphrodisiac.
Till date, any assessment of threat categories to species in IHR is generally based on qualitative observations (Pangtey and Samant, 1988;Samant et al., 1993Samant et al., , 1996 a,b; a,b;Pandey and Well, 1997;Kala et al., 1998;Uniyal et al., 2002).Only a few studies have considered both qualitative and quantitative attributes for the assessment of species status (Airi et al., 2000;Nautiyal et al., 2002;Bhatt et al., 2007).
As quantitative infor-mation on a species plays a vital role in formulating a conservation plan and in understanding the ecology of the species (Uniyal et al., 2002), thus, the aim of the study was: a detailed survey of these aconites for quan-titative analysis throughout the Kumaun region.This is an attempt to provide quantitative details of A. ferox Wall.ex Ser. and A. heterophyllum Wall.ex Royle through assessment of the distribution patterns and quantum of availability.Also, it will provide essentially simple and assimilated data on current status of species population which can be used for assigning the categories of threat as suggested under IUCN Red List Categories (1993).

Vegetation sampling and analysis
For the phytosociological study in every study sites, 30 quadrats of 1 × 1 m (1sq m) size at different altitudinal range were randomly laid (Misra, 1968).For population analysis and threat category determination, strands of 100 × 100 m 2 were identified and marked on each site.Vegetation sampling was conducted through vertical transect method (Michel, 1990).Since the distribution range is narrow and topography is diverse, approximately 60 m long and 30 m wide transect was laid in each strand.Transect were divided into 3 plots of 20 X10 m size as replicates and 10 quadrats of 1X1 m were laid randomly in each plot following Kershaw 1973.The threat category of a species was identified using six attributes (habitat preference, distribution range, population size, use pattern, extraction trend, native and endemic species) and following Samant et al. (1998) and Ved et al. (2003).

Quantitative analysis
The quantitative analysis such as density, frequency, and abundance of tree, shrubs and herbs species were determined as Bhatt et al. 113 per Curtis and McIntosh (1950).The species richness of the vascular plants was computed by using the method 'Menhinick's richness index (DMn) (Whittaker, 1977).The diversity index (H), was calculated by using Shannon-Wiener information Index (Shannon and Wiener, 1963).The concentration of dominance (Cd) was calculated by Simpson's Index (Simpson 1949).

Statistical techniques
Correlation between Density and Important value index (IVI) of the two species is computed through Carl Pearson's method.Regression has been subjected to density and important value index (IVI) of the study area.A curve that describes the distribution of probability over the values of a random variable is drawn with the help of Statistical Package for the Social Sciences (SPSS) software.Phytograph of both plant species is plotted to describe the phytosociological status of the plant using window 2007 'EXCEL' software.

Occurrence and availability
Performance details, at different altitudes, of identified taxa A. ferox is presented in Table 1.A.ferox grows well in Shady moist alpine slopes.The density of A.f erox ranged between 0.60 individual / m 2 (P4) to 1.10 individual / m 2 (P5).The frequency of occurrence was varied between 40% (P4) to 63.33% (P7) and comparable to other associated species.The abundance to frequency (A/F) ratio of A. ferox revealed that species was distributed regularly in the five populations (P1, P2, P3, P4 and P7).Few other populations, P5 and P6 showed random distribution patterns (Table 1 and Figure 2).
A. heterophyllum showed best growth in natural habitat at two sites: P1 and P4.The density of A. heterophyllum varied between 0.21 individual / m2 (P4) to 0.62 individual / m2 (P6).The frequency of occurrence was relatively better (60% for P3 to 76.67% for P2, P4, and P7).The species largely prefers the southeast facing slope.Distribution pattern of A. heterophyllum shows that the species was distributed regularly in most of the populations (P2, P4, P5, P6 and P7); only two populations (P1, P3) showed random distribution (Table 2 and Figure 3).

A. heterophyllum
Considering that the IVI provides an excellent marker for determining the status of distribution and availability across varying environmental and biotic conditions (Negi et al., 1992;Ram and Arya, 1991), value of both identified taxa was compared.Values varied from one population to other.This difference can be attributed to varying species number, topography, biotic and abiotic interferences in community (Nautiyal, 1996).A. ferox had maximum IVI at P6 (9.29) in forest edges, Rhododendron forest margin while it was recorded minimum in P4 (5.44) where habitat was shady moist alpine slope.A. heterophyllum showed maximum IVI value of 9.70 in P2 and lowest value of 7.76 in P5.Phytograph of each species (Figures 4 and 5) was drawn to clarify the phytosociological attribute of the species.In order to check the dispersal of both species, the normal probability curve (NPC) has been plotted for species richness against normal distribution.The plotted points do not fit the line well, and curve away from it in places; it is a non normal distribution.It indicates that the distribution of both species in selected sites is skew (Figures 6 and 7).

Regression
Regression has been subjected to density and IVI of both the species.Significant positive correlation was found between both the characters that density and IVI at p<0.001 level of significance.Density was taken as independent variable and IVI as dependent.Regression equation for A.ferox is y = 6.2195x + 1.8808, R square is 0.7621.For A. heterophyllum regression equation was y = 0.3728x + 8.6001, R square is 0.0043.From this equation relation between density and IVI can be calculated in the natural habitat.

Threat categorization
An area-specific threat categorization of species is very important for short or long-term management planning.The information, thus generated, has immense potential for contributing in threat categorization, conservation and management of threatened plant species (Hutchings, 1991).On the basis of the above interpretations and following Samant et al. (1998) and Ved et al. (2003), threat category of the species was identified using six attributes (habitat preference, distribution range, population size, use pattern, extraction trend, native and endemic species).In the present study, both the species of aconite, namely A. ferox and A. heterophyllum seems to be endangered in Kumaun Himalaya while assessed as critically endangered and vulnerable CAMP (2003).These observations would also be helpful in determining the status of other species and can be applied for conservation strategies.

DISCUSSION
Low seed viability, obstruction of reproductive phases by juvenile, fronts and early snow fall coupled with biotic interference prevents seed maturation and reduced plant population in most of alpine vegetation (Pandey et al., 1997); hence they emerge through underground parenting organs (tubers).Studies on quantitative assessment play a vital role in the ecology of the species (Uniyal et al., 2002).It helps in determining the performance of populations under different sets of conditions and provides desired information about the specialized ecological requirements of a taxon (Kaul and Handa, 2001).The information, thus generated quantitatively clears that population of A. ferox and A. heterophyllum is severely fragmented (low population density and restricted distribution of species).This has conservation implications because species with specific habitat requirements have greater possibilities of extinction than species with a broad habitat range.In addition, a minimum population size is required for the long-term viability of threatened species (Cunningham and Saigo, 1999).Considering the higher frequency of occurrence in some populations is indicative that species     have potential for better performance in these sites (habitats) in the region and can be used for mass propagation/cultivation.

Figure 1 .
Figure 1.Map of study sites.
Frequency = Total number of quadrats studied Total number of individuals of a species in all quadrats Density = Total number of quadrats studied Total number of individuals of a species in all quadrats Abundance = Total number of quadrats in which the species occurred Abundance A/F ratio = Frequency Pattern of the species was analyzed on the basis of abundance to frequency (A/F) ratio.Similarly relative values of frequency, density and dominance and Importance Value Index (IVI) were computed following the methods of Curtis (1959) as: Percent frequency of species Relative frequency = x100 Total percent frequency of community Density of species Relative density = x 100 Total density of the community Total basal cover of species Relative dominance = x 100 Total basal cover of the community (Cbh)2 Basal area = 4 Total basal cover (TBC) = Mean basal cover  Density Importance Value Index (IVI) = Relative frequency + Relative density + Relative dominance.

Table 1 .
Phytosociological characters of A.ferox at different sites in Kumaun Himalaya.

Table 2 .
Phytosociological characters of A.heterophyllum at different sites in Kumaun Himalaya.

Table 3 .
Diversity indices of sampling plots for A.ferox and A. heterophyllum.Dispersal species of A. ferox through NPC.
Dispersal species of A. heterophyllum through NPC.