Environmental Science
Vol. 37, No. 2, pp. 104-115, June, 2021 https://doi.org/10.7747/JFES.2021.37.2.104
Variation of Medicinal Plants Species Richness along Vertical Gradient in Makawanpur District, Nepal
Damodar Gaire1,2,*, Lichun Jiang1, Vijay Kumar Yadav2, Jit Narayan Shah3, Sunita Dhungana3, Anju Upadhyaya3, Shiv Kumar Manjan2 and Binod Kumar Heyojoo3
1Northeast Forestry University (NEFU), Harbin 150040, China
2Tribhuvan University, Institute of Forestry (IOF), Hetauda, Makawanpur 44618, Nepal
3Tribhuvan University, Institute of Forestry, Pokhara, Kaski 33700, Nepal
Abstract
The research attempted to analyze the medicinal plant species richness in the vertical gradient from lower to the highest elevation of Makawanpur, focusing on the relationship between species richness and elevation which is very important for conservation and management of species diversity. Inventory was carried out in the study area by taking sampling intensity of 0.5% in the effective area. Altogether, 42 sample plots were laid in the field with the help of GIS software maintaining 50 m altitude difference. High species diversity was found in the herbs species whereas shrubs have com- paratively low species diversity. The maximum species richness is found in herbs and poles whereas shrubs and trees have relatively low species richness. Research showed that species richness of medicinal plants increased with altitudinal gradient. While analyzing the species richness from 350 to 2,550 m (msl), the highest species richness was received with the elevation ranges from 1,800 m to 2,300 m. There was a positive relationship between species richness and altitudinal gradient in the study area. In addition, we have recorded the high value medicinal plants after 1,800 m altitude and rarely within 1,000 m. Medicinal plants correlated both positive and negative relationships with the increased altitude. The altitudinal response has positively seen except density (n/ha) of Shrubs. Domestication and cultivation of high value medicinal plants should be promoted in community forest including private lands. Training, workshops and awareness programs should be conducted to make people aware about medicinal plants resource utilization, conservation and commercialization of available medicinal plants.
Key Words: medicinal plants, diversity, inventory, gradient, species richness
Received: September 1, 2020. Revised: May 12, 2021. Accepted: May 13, 2021.
Corresponding author: Damodar Gaire
Tribhuvan University, Institute of Forestry (IOF), Hetauda, Makawanpur 44618, Nepal Tel: +977-57520453, Fax: +977-57520865, E-mail: [email protected]
Introduction
Physiographically, Nepal has the largest elevation gra- dient in the world (Li and Feng 2015), extending from tropical alluvial plains as low as 59 m to the alpine-nival Himalayan region (＞5,000 m). Along with physiographical differentiation, it has high variation of climate, rainfall and
soil (Miehe et al. 2015). This diverse terrain is home to over 6,500 species of flowering plants (Kunwar et al. 2018) and over 300 species of endemic plants (Tiwari et al. 2019).
Variation in species richness along geographical and en- vironmental gradients is a central topic in the fields of ecol- ogy and biogeography because species diversity influences community stability and ecosystem functioning (Rokaya et
al. 2012). Species richness is currently the most widely used measure of diversity (Stirling and Wilsey 2001). Around 7000 species of flowering plants have been documented for Nepal (Department of Plant Resources 2001). Of these, around 1792 species (including lichens and fungi) were used for medicinal purposes (Baral and Kurmi 2006). On a broader scale, plant diversity correlates with the size of the area (Rosenzweig 1995), elevation (Stevens 1992). Aspect significantly influences richness and composition of plants by interpolated value analyzed. Nepal covers two-thirds of the Himalayan range with eight highest mountains in the world. Variation in elevation from tropical to nival regions in south-north direction in Nepal has favored rich bio- diversity (Shakya et al. 2007). Climate had an important role in explaining the elevation pattern of species richness.
Patterns of species richness across gradients depend on the interaction between the individual species’ range of toler- ance and competition (Dobrowski et al. 2015). The Medicinal plants (MPs) are a major component of tropical to alpine vegetation globally. Different methods and approaches have been applied to describe the variation in vascular plants spe- cies diversity and composition along elevation gradients in different floristic areas of the world (Bhattarai and Vetaas 2003).
A hump-shaped relationship between orchid species richness and elevation was observed in Nepal and Bhutan, with maximum richness at 1600 m corresponding to 160°C mean annual temperature (Acharya et al. 2011). Several ele- vation patterns for species richness have been described monotonically decreasing patterns with elevation (Tang and Fang 2004). Species richness will peak at the elevation where the combination of growing conditions is optimal (Lomolino 2001). A pattern of richness increasing with higher pH has been reported in the Arctic tundra. Aspect regulates the quantity and duration of soil moisture, partly through temperature (Parker 1991). An understanding of aspect is important in forest management and planning (Bale et al. 1998). Medicinal plant commercialization is a rare opportunity to increase locally derived and controlled incomes with a range of positive outcomes, such as support- ing livelihood strategies and mitigating the negative effects of outmigration (Timmermann and Smith-Hall 2019).
The study of the relationship between species richness and elevation is important for conservation and management of
species diversity (Grytnes 2003) because the lack of de- tailed knowledge about distribution patterns of species and ecosystems leads to problems in conserving species (Hunter and Yonzon 1993). Species richness in relation to elevation has received extensive attention because short geographical distances can produce large climatic gradients as the elevation changes (Körner 2007). Elevation gra- dients provide unique opportunities to test ecological theo- ries and explore the effects of climate change on species richness and may help us interpret deviations from lat- itude-related patterns (Guo et al. 2013).
The main objective of the study was to analyze the spe- cies richness of medicinal plants along the vertical gradient.
The study was carried out within the community forests of Makawanpur district of Nepal elevating from 350 to 2,550 m (msl). In this study, we have focused on medium to high-value medicinal plants according to human uses and the present market scenario. While increasing the altitude, the diversity of high valued medicinal plants also increases if there is no human interference. The community forests where studied, have been well managed and controlled hu- man interferences.
Materials and Methods
Study area
The study was carried out in Makawanpur district of Nepal, ranging from 350 m to 2,550 m from msl. The study was carried out from the premises of Institute of Forestry (IOF) with an altitude of 350 m to the top of the Daman hills with the elevation of 2,528 m. The study area, Daman (27°36'29''N, 85°5'39''E) is a southern part of Makawanpur district (about 80 km south-west of Kathmandu) in prov- ince no 3, Nepal. The study was carried out in Thaha mu- nicipality, Kailash and Bhimphidi rural municipality.
Daman is an ecotone region of Terai Arc landscape area (TAL) and Chitwan-Annapurna Landscape (CHAL). It lies in the tropical to lower temperate region of Central Nepal. The altitude varies from 350 m to 2,500 m. That area has a warmer to cold climate. Daman is an important biodiversity hotspot area for MPs like Tinospora sinensis, Valeriana jatamansii, Zanthoxylum armatum, Phyllanthus emblica, Piper longum, Azadirachta indica etc. This area hosts a continuous succession of tropical rainforests, sub-
Fig. 1. Elevation map of the study area.
Table 1. Measurement plot size for different types of plant size
Type Plant size Plot size Radius
Tree ＞30 cm DBH 25 m×20 m 12.61 m
Pole 10-29.9 cm DBH 10 m×10 m 5.64 m Shrub/sapling ＜10 cm DBH
and＞1 m height
5 m×5 m 2.82 m
Herb ＜1 m height 2 m×2 m 1.12 m
Source: NTFPs inventory Guideline 2012.
Fig. 2. Laying out the sample plots.
tropical evergreen, broad-leaved forests, subalpine conifer forests, rhododendron forest. A combination of high spe- cies richness and large elevation gradients over relatively short distances makes this location an ideal place to evaluate the elevation effects on species richness (Fig. 1).
Key methods
The purposive sampling was carried out to capture the data from the field. With the help of GPS, we calculated the altitudinal difference of 50 m along the vertical gradient in the study area. Each 50 m altitude interval, we marked the GPS points and captured the biophysical data in each meas- uring plot. In order to get more accuracy, plot measurement should conduct below the difference of 100 m along the vertical gradient. Altogether, 42 sample plots were demar- cated in order to biophysical data of the medicinal plants/NTFPs (Fig. 2). The Institute of Forestry (IOF)/
Nepal established these plots as permanent research plots for the further data capturing in the future. The inventory
data was managed using the following inventory guideline (Table 1).
This research is based on data available during field surveys. However, we conducted the key informants inter- view, direct observation and Focus Group Discussion (FGDs) for identifying the local name of the recorded me- dicinal plants. The collected data were analyzed to calculate species richness, density, relative density, frequency, and rel- ative frequency of medicinal plants along the vertical gradients.
Bio-physical data analysis
The parameters for the distribution and availability of the plants were species richness and abundance using den- sity and frequency as indicators. For each species data were analyzed to assess density, relative density, frequency, and relative frequency. The herbarium of each medicinal plant species has been placed in the museum of the Institute of Forestry (IOF), Hetauda Campus for enhancing the
Fig. 3. Species distribution in plots.
knowledge of students. The quantitative biophysical data were analyzed by using the following formula:
Species diversity
Species diversity accounts for the richness and present of each sub species from a biodiversity sample within a zone.
Shannon Weiner Index H'=−
Here,
H'=index of species diversity
S=species richness (total no. of species present) Pi=proportion of each species in sample Ln=natural log
Biologically realistic H' values range from 0 (only one species presents with no uncertainty as to what species each individual will be) to about 4.5 (high uncertainty as species are relatively evenly distributed). In theory the H' value can be much higher than 4.5, although most real world esti- mates of H' range from 1.5 to 3.5. In general, it is thought that more distributed and less stable environments have lower H' values.
Frequency=
×100
Relative frequency=
×100
Population density per ha=
×10,000
Relative density=
×100
Species richness index
Species richness is the total number of different organ- isms present. It doesn’t take into account the proportion and distribution of each species within a zone.
Species richness index=N/√S Where S=No. of species in a collection
N=No. of individuals collected
Species evenness index
Evenness is a measure of how similar the abundance of differences are. When there are similar proportions of all species then evenness is one; when abundance is very dis- similar then the value decreases. The value for evenness lies between 0 and 1.
E=H'/Hmax
Where E=Species Evenness Index Hmax=ln(S)
S=Total no. of species.
Species dominance
Simpson’s index of biodiversity
SID=1/D (reciprocal) or SID=1-D (complementary) DS =∑ni(ni-1)
N (N-1) Where
Ds=Simpson’s index
n=total number of organisms of a particular species N=The total number of organisms of all species The value of D ranges between 0 and 1. Higher the val- ue of SID, the lesser the dominance of that species.
Results and Discussion
Summary plot
Using R software, we have summarized the nature of plot summary with respect to the number of species in dif- ferent categories. The numbers of species are homoge- neously distributed along the vertical gradients in the study
Table 2. Status of medicinal plants under tree category
S.N Altitudinal range Name of tree species Number of species
Relative
frequency Density/ha Remarks
1 350-400 Cassia Fistula 2 2.3 0.95
2 400-450 Syzygium operculata 3 3.45 1.43
3 450-500 Saraca Longifolia 2 2.3 0.95
4 500-550 Azadirachta indica 2 2.3 0.95
5 550-1,050 Phyllanthus emblica 3 3.45 1.43
6 700-750 Syzygium cumini 2 2.3 0.95
7 950-1,000 Elaeocarpus ganitrus 2 2.3 0.95
8 650-700 Acacia catechue 3 3.45 1.43
9 800-1,350 Bassia butyracea 6 6.9 2.86
10 950-1,000 Sapindus mukorossi 3 3.45 1.43
11 800-1,100 Choerospondias axillaris 3 3.45 1.43
12 1,100-2,050 Myrica esculenta 11 12.64 5.24
13 1,250-1,300 Pyrus pashia Buch 3 3.45 1.43
14 1,350-2,150 Persea odoratissima 3 3.45 1.43
15 1,450-2,400 Rhododendron arboreum 20 22.99 9.52
16 1,650-2,200 Daphniphyllum himalense 3 3.45 1.43
17 1,700-2,300 Aesculus indica 6 6.9 2.86
18 1,750-2,350 Taxus wallichiana 8 9.2 3.81
19 2,200-2,400 Juglans regia 2 2.3 0.95
Total 87 100
area. Among the 42 plots, medicinal plants species richness increased or decreased. However potentiality of species richness increased along the vertical gradients. The sum- marized plot information has been presented Fig. 3.
In this study, the medicinal plant species have been fo- cused depending upon the medicinal value used by local people as primary health care, and high valued medicinal plants. The local names of these medicinal plants were iden- tified using key informants’ interviews and Focus Group Discussions (FDGs). The plants enlisted in the higher alti- tude had high-value medicinal plants in comparison to the lower altitude.
Status of medicinal plants under tree category After capturing the biophysical information of 42 plots, the summary table for trees under medicinal plants reveals that Rhododendron has a highest relative frequency (22.99) compared to other species. Compared to other plant catego- ries, we have only recorded 19 major medicinal plants spe- cies under tree category. The diversity of medicinal plants under medicinal plants was low compared to shrubs and herbs.
Therefore, out of 19 tree species (medicinal plants) re- corded in the study area, Rhododendron species was re- ceived the highest number (20), followed by Myrica escu- lenta (11), Taxus wallichii (8), Bassia butyraceae (6), and other species which have been shown in above table. The study area is also the prime habitat of Texus wallichiana. It received attention recently as its leaves and bark were found to be the prime source of taxol, a potent anticancer drug (Juyal et al. 2014) (Table 2; Fig. 4).
Status of medicinal plants/NTFPs (shrubs)
Altitude-wise medicinal plants species richness under shrub category has been recorded relatively low compared with trees and herbs categories. Kadipatta, Dhasingre, Adhatoda vasica, and Artemisia vulgaris were the highest abundance compared to others. Gaultheria procumbens is the key species for extracting the valuable essential oil.
Murraya koenigii has higher relative frequency and density comparing to other shrub species shown in the Table 3.
Status of medicinal plants (regeneration/herbs) The following medicinal plants have been enlisted as ma-
Table 3. Status of medicinal plants under shrubs category
S.N. Altitude Shrub species Number of plants Relative frequency Density (n/ha) Relative density
1 350-1,100 Murraya Koenigii 15 15.96 142.86 15.96
2 550-1,600 Adhatoda vasica 14 14.89 133.33 14.89
3 500-1,250 Artemisia vulgaris 9 9.57 85.71 9.57
4 500-600 Urtica dioica 5 5.32 47.62 5.32
5 650-1,550 Vitex negundo 4 4.26 38.1 4.26
6 900-1,000 Ziziphus mauritiana 2 2.13 19.05 2.13
7 1,100-1,200 Girardiana diversitifolia 8 8.51 76.19 8.51
8 1,200-2,400 Gaultheria fragrantissima 9 9.57 85.71 9.57
9 1,500-2,200 Berberis aristata 7 7.45 66.67 7.45
10 1,800-2,400 Daphne Species 7 7.45 66.67 7.45
11 1,800-2,200 Mahonia napaulensis 6 6.38 57.14 6.38
12 1,500-2,400 Drepanostachyum falcatum 8 8.51 76.19 8.51
Total 94 100 100
Fig. 4. Number of medicinal plants species (trees).
jor medicinal plants under herbs categories which was cap- tured the plot of 1 m2. Satuwa (Paris polyphylla), Sugandhawal (Valeriana jatamansi), Ban Mula and Chiraito (Swertia chirayita) are the most potential medicinal plants in the study area. Higher the altitude high values of medicinal plants were captured during field study. The detail of me- dicinal plants with respect to altitude has been presented in Table 4. The majority of seedlings were herbs category (Medicinal plants).
Altogether, we observed 37 species medicinal plants un- der herbs categories which was compatibly higher than tree and shrubs species. The major high value medicinal plants were under herbs category. High value medicinal plants have been the basis for modern allopathic drug develop- ment while the use of indigenous drugs from plant origin form major part of complementary and alternative medi- cines in the form of herbal drugs and Ayurvedic medicines.
In this study area, high value medicinal plants was received in herb category rather than trees and Shrubs. Paris poly- phylla, Valeriana jatamansi, Rheum austral and Swertia chirayita are precious herbs which were recorded between 2,000 to 2,500 m (msl) in the study area.
Altitude-wise response of medicinal plants
While comparing the medicinal plant species, the high- est number of tree species was received from 1,000-2,000 m altitude from msl. The highest numbers of shrub species were recorded from 1,600 to 2,500 m. Likewise, the highest number was recorded from 1,500 m to 2,200 m under herbs medicinal plants. Majority of the species were ob- tained from 1,500-2,000 under different categories. The data recorded areas were under the control of grazing and controlled silvicultural operations (Fig. 5).
Table 4. Status of regeneration of medicinal plants
S.N. Altitude Name of medicinal plants Number Relative frequency Density (n/ha) Relative density
1 350-1,500 Tinospora cordifolia 9 2.03 2,142.86 2.03
2 350-500 Rauwolfia serpentina 10 2.26 2,380.95 2.26
3 350-1,600 Coccinia grandis 13 2.93 3,095.24 2.93
4 350-1,500 Cissampelos pareira 21 4.74 5,000.00 4.74
5 350-900 Dioscorea deltoidea 7 1.58 1,666.67 1.58
6 500-2,000 Arisaema speciosum 17 3.84 4,047.62 3.84
7 450-1,500 Cheilanthes dalhousiae 5 1.13 1,190.48 1.13
8 300-1,400 Shakhari Jara (Local Name) 8 1.81 1,904.76 1.81
9 350-1,900 Piper longum (Wild) 13 2.93 3,095.24 2.93
10 1,000-2,100 Harchur 11 2.48 2,619.05 2.48
11 600-1,400 Costus igneus 8 1.81 1,904.76 1.81
12 350-1,200 Bacopa monnieri 18 4.06 4,285.71 4.06
13 350-1,200 Oxylis latifolia 10 2.26 2,380.95 2.26
14 600-1,500 Dioscorea deltoidea 4 0.90 952.38 0.90
15 1,800-2,200 Aconitum bisma 1 0.23 238.10 0.23
16 2,000-4,000 Bahadure (LN) 13 2.93 3,095.24 2.93
17 350-2,000 Cissampelos pareira 7 1.58 1,666.67 1.58
18 1,500-1,800 Cyperus alternifolius 5 1.13 1,190.48 1.13
19 2,000-2,500 Ipomoea hederacea 26 5.87 6,190.48 5.87
20 700-1,800 Nephrolepis cordifolia 25 5.64 5,952.38 5.64
21 1,200-1,800 Makarkache (LN) 7 1.58 1,666.67 1.58
22 800-1,700 Smilax zeylanica 5 1.13 1,190.48 1.13
23 1,500-2,500 Bergerina ciliata 17 3.84 4,047.62 3.84
24 1,800-2,400 Astibe rivularis 16 3.61 3,809.52 3.61
25 1,800-2,400 Barleria prionitis 24 5.42 5,714.29 5.42
26 1,200-2,400 Acorus calamus 12 2.71 2,857.14 2.71
27 1,900-2,300 Swertia Chirayita 15 3.39 3,571.43 3.39
28 1,700-2,100 Glycyrriza glabra 14 3.16 3,333.33 3.16
29 1,700-1,900 Anaphalis contorta 4 0.90 952.38 0.90
30 1,200-2,100 Cinnamomum bejolghota 15 3.39 3,571.43 3.39
31 1,400-2,100 Mukuna monosperma 8 1.81 1,904.76 1.81
32 1,900-2,400 Aconitum bisum 8 1.81 1,904.76 1.81
33 1,600-2,500 Banmula (LN) 24 5.42 5,714.29 5.42
34 2,200-2,500 Valeriana jatamansi 14 3.16 3,333.33 3.16
35 2,200-2,400 Gokul dhup plant (LN) 11 2.48 2,619.05 2.48
36 1,800-2,400 Rheum australe 8 1.81 1,904.76 1.81
37 2,000-2,500 Paris Polyphylla 10 2.26 2,380.95 2.26
Total 443 100.00 100.00
Correlation analysis
Medicinal plants respond to both positive and negative relationships with the increased altitude. The altitudinal re- sponse has positively seen except density/ha (Shrubs) category. However, they were not strongly correlated with altitudinal gradients. Species have distributed homoge-
neously rather than heterogeneously.
While comparing the variables, the majority of the varia- bles were positive relations. In the case of altitude variable, density/ha of shrubs was analyzed as a negative correlation (-0.11). Other variables were analyzed as positive relation with increase in altitude. Among the plants in the study area, medicinal plants were only recorded according to their
Fig. 5. Graphical representation of medicinal plants with respect to altitude.
Table 5. Correlation analysis matrix
Variables 1 2 3 4 5 6 7 8
Altitude (1) 1.00
Number of trees (2) 0.41 1.00
Number of poles (3) 0.17 0.25 1.00
Number of shrubs (4) 0.34 0.29 0.20 1.00
Number of herbs (5) 0.33 0.00 -0.16 0.19 1.00
Density/ha (tree) (6) 0.18 0.04 0.14 0.16 0.18 1.00
Density/ha (shrubs) (7) -0.11 0.01 -0.13 -0.31 -0.34 -0.09 1.00
Density/ha (herbs) (8) 0.11 -0.02 0.04 0.05 0.25 -0.27 0.11 1.00
Fig. 6. Species richness index.
medicinal or Ayurveda values, international significant and economic contribution to livelihoods of local people. The details of correlation values of variables have been pre- sented in Table 5.
Species richness
Species richness is the number of species within a de- fined region. The species richness of a region is obtained through sampling or via a census (Moore 2013). In the study area, species richness of herbs was received the high- est value (1.34) in herbs and smallest value (0.87) in trees (Fig. 6).
The species richness of Herbs was received as 1.34 fol- lowed by shrubs (1.01), pole (0.9) and trees (0.87).
Numbers and diversity of medicinal plants under the herb
category was received the highest compared with trees and shrubs. We have focused on species with high value medici-
Fig. 7. Simpson diversity index of dominance. Fig. 8. Species Evenness Index.
nal plants. The selected sites for the study area were well managed forests where there were controlled grazing, fire management and limited human interference except con- trolled silvicultural operations. In that case, medicinal plants under the herb category received the highest species richness. The main reason for the tree species richness in- dex was that we only selected the trees which have medicinal value and contribution to the local people.
Simpson diversity index of dominance
In order to quantify the biodiversity of habit, Simpson diversity index of dominance was used. The result revealed that there was dominance of medicinal plants under herb categories (Fig. 7).
The overall dominance in the study area was herbs (0.95) followed by shrubs (0.8), pole (0.67) and trees (0.6). The data were only recorded plants which have medicinal value along the vertical gradient.
Species evenness
Species evenness takes into account the number of spe- cies and the relative abundance of species in a community (Moore 2013). According to the Species Evenness Index, species is more evenly distributed among tree species and herb species are unevenly distributed. While analyzing the data, we received the highest evenness index of tree species.
It was because of the fact that the majority of dominance medicinal tree species were Taxus wallichiana and Rhododendron Species, and these species are homogenously distributed in the study area (Fig. 8).
Species overlap along the vertical gradient
According to the nature of medicinal plants, species overlapping along the altitudinal gradient was so interesting.
Chillobadulpate, Paneswaaro, Bajradanti and Adhatoda va- sica were observed with more range overlapped compared to other species (Table 6).
Overlapping of medicinal plant species was common in the study area. The climatic, adaptability and topographic are the major factors that influence on overlapping the plant species in different vertical gradients. Out of the species, Rhododendron species was received with maximum alti- tude overlapping (75%) from 1,500-2,550 m (msl).
Altitudinal distribution of medicinal plants
High value medicinal plants increased with increase in altitude. However, Tinospora cordifolia and Rauwolfia ser- pentina were recorded in the lower elevation. Even the in- crease in vertical gradient with 50 m difference, species richness increased or decreased. Species composition and richness was changed after increasing altitude, which di- rectly related to vertical gradients (Fig. 9).
Number of Herbs species was remarkably higher than shrub, pole and shrub categories. The area is best suited for medicinal plants under herb categories.
Species distribution
Litter cover of organic matter with respect to species has been analyzed using R software. Species distribution be- tween 2,200-2,500 was more effective among Paniswaro, Taxus wallichiana, Bergenia cilata, Swertia chirayita and
Fig. 9. Altitudinal distribution of medicinal plants.
Fig. 10. Species distribution and indicators.
Valerana jatamansi. Among others, Bergenia ciliata was sighted in higher rocky slope. Well drained soil with mini- mum litter cover is essential for Pakhanved. In case of swer- tia chirayita, it loves the good soil depth or litter cover.
Swertia chirayita with more litter cover from Oak species was remarkably bigger in size in the study area. Sloppy ter- race with more organic matter from litter cover was the best situation for Swertia chirayita. Taxus wallichina was sighted with minimum leaf litter. Aspect, slope, organic matter dep- osition and climatic condition are heavily depended on the well growth of medicinal plants. We observed the healthy seedling of Chirayita where there is more organic matter deposition with medium crown opening of tree species.
Paris polyphylla prefers the moist areas or shaded areas.
Taxus wallichil prefers the soil with organic matter deposi- tion in the northern aspect. Unlike from Swertia chirayita, Pakhanved prefers the drained soil with steeply slope (Fig. 10).
Table 6. Species overlap along the vertical gradient AltitudeRauwolfia serpentinaTinospora cordifoliaPiper langumChillo- badulpateGurjo GanuSakhari JaraKadipattaAdhatoda vasicaArtemisia vulgaris
Rhodo- dendron sppsBanmulaBahadurePaniswaroPasanbhedMakark- ancheSarpako MakaiSugandha walPotentilla fulgensSwertia chirataRemarks 400-600 600-800 800-1,000 1,000-1,200 1,200-1,400 1,400-1,600 1,600-1,800 1,800-2,000 2,000-2,200 2,200-2,400 2,400-2,600 % Overlap8.32587533817332575333350503367175050
Conclusion
While comparing the medicinal plant species, the high- est number of tree species was received from 1,000-2,000 m altitude. Similarly, the highest numbers of shrub species were recorded from 1,600 to 2,500 m altitude (for shrub) and 1,500 m to 2,200 m altitude (for herbs). 1,500 to 2,000 m altitude is the cross cutting for tree, shrubs and Herbs categories of medicinal plants. While analyzing the species richness from 350 to 2,550 msl, the highest species richness was received with the elevation ranges from 1,800 m to 2,300 m. There was a positive relationship between species richness and altitudinal gradient in the study area. High species diversity was found in the herbs species whereas shrubs have comparatively low species diversity. The max- imum species richness is found in herbs whereas shrub and tree has relatively low species richness.
Institute of Forestry (IOF) should establish the perma- nent plot for capturing data on the basic of altitudinal gra- dients as regular (Annual basic) which will be better for stu- dents as practical means. Domestication and cultivation of high value medicinal plants should be promoted in com- munity forest including private lands. Further research on nursery practices valuable medicinal and aromatic plants in a long vertical gradient should be carried out for in the fu- ture study.
Acknowledgements
The authors acknowledge the Tribhuvan University, Office of the dean for granting permission to study the me- dicinal plants species richness along the vertical gradient in Makawanpur district, Nepal. We sincerely thank Riseshwor, Hatemalo and Parbati CFUGs for issuing the permission for the collection of data. Special thanks go to Prof. Dr.
Lichun Jiang, Professor Prof. Dr. Krishna Raj Tiwari, Prof.
Dr. Santosh Rayamajhi and A. Prof. Mahendra Singh Thapa for providing the feedback and comments for the research.
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