The river Alaknanda originates in the glacial region (Alkapuri glacier) of Himalaya in the district Chamoli of Uttarakhand state and enters in district Pauri Garhwal. The human influence on biodiversity and ecosystem functioning have largely taken in the form of rapid, large and frequent changes in land and resource use, increased frequency of biotic invasion, reduction in species number, creation of stresses and the potential for changes in climatic systems [1]. Such changes have a direct impact through habitat destruction and over exploitation of resources affect biodiversity [2] of that particular place. Gauthier et al. [3] described that the vegetation dynamics of forest systems are controlled by numerous factors such as the available pool of species, the physical characteristics of the land, soil fertility, climate and disturbance regime characteristics. Anthropogenic disturbances occur in chronic form involving removal of a small amount of biomass at any given time, but persisting all the year, without any respite for recovery [4].

Depletion of biodiversity is today’s alarming problem all over the world. Extinction rate has been enhanced by human intervention resulting into habitat loss and climate change. Many species have eliminated from areas dominated by human influences [5]. The loss of biodiversity actually hampers and contrasts economic development [6], is an alarming problem of the world. The rate of extinction has been enhanced by human-related habitat loss and climate change [7]. Dam constructions in Himalayan rivers are considered one of the major sources of economy generation and fulfil the need of country’s electricity. Although construction of dams are affecting the biodiversity of surrounding areas and also affecting needs of local villages which are closely linked with biodiversity for several daily requirement . It has been observed that in the several areas, local forest community are the source of different needs to the local villagers including their culture attachment.

Keeping in view the importance of biodiversity, the resources used by local villagers and their consequent losses due to human activities especially for dam constructions, the present study was taken with the aim to assess the vegetation and soil resources in influenced zone of Hydroelectric Project in Srinagar valley with the following objectives that:

i) Estimation of soil attributed of the influenced zone.

ii) Forest composition and distribution pattern of species in the influenced zone.

iii) Documentation the resources used by the local inhabitant.

iv) Consequences of anthropogenic pressure on inhabitant future life.

Study area

The soil and vegetation study in influenced zone of hydroelectric was carried out between the villages of Supana and Dhari Devi which cover the distance of 12 km. The study was done in the right side forest area between the selected villages towards the stream flow. The area falls under sub-tropical region. The area is located between 300 14.472’ N latitude and 780 49.953’ E longitude at an elevation ranges between 535-630 m. The total height of dam is expected 93 m (submergence zone) which is marked from the initial river flow (winter season) at an elevation 535 m above sea level and the study was taken above the area of 100 m from 535 to 635 (Figure 1).

Figure 1: Location map of the study area.

Climate and vegetation

The climate of the study area is of monsoon type and has three different marked seasons in a year, viz.; rainy, winter and summer. The mean annual temperature ranges between 17ºC to 23ºC and the mean annual rainfall 960 mm. In tree layer the dominant species observed was with associated species of however, in shrub layer dominant species reported and other associated species were. The          pattern was both rain fed and irrigated. The main occupation of the villages is agriculture with small land holding.

Soil sampling

The soil sampling in the influenced zone was done based on sites selection. The total area was categorized for sampling into five sub-sites based of variability observed in the vegetations pattern in influenced zone. The soil analysis was done by collecting three samples randomly from each site using two different depths i.e. 0-30, 30-60 cm. Thus, from entire five sites and two depths of influenced zone, total 30 samples were collected for analysis.

Soil analysis

The soil samples were mixed well before use. The samples were air dried at 20 to 25°C and 20% to 60% relative humidity [8] for further use. Moisture percentage was calculated by samples placed in oven at 100 ± 2°C till their successive weights constant. Water Holding Capacity (WHC) and texture% of soil was determined according Misra [9]. Bulk Density (BD) of soil was determined by taking known volume of soil without disturbing the natural soil structure, dried to remove the water and weight the dry mass. Soil (1:2.5, soil: water) suspension was used to measure pH with the help of dynamic digital pH meter. Soil Organic Carbon (SOC) was determined by Walkley and Black’s rapid titration method [10]. Exchangeable phosphorus (P) and available potassium (K) was determined as methods described by Jackson [8].

Vegetation sampling and analysis

The vegetation analysis was done by using fifty (50) quadrats from entire influenced zone. A total of 10 randomly placed quadrats were used each a size of 10×10 m² for trees, 5×5 m² for shrubs and 1×1 m² for herbs. The size and number of quadrats were determined based on species area curve [9] and the runnings mean methods [11]. In each quadrat, tree ≥30 cm girth (at 1.37 m from the ground) was considered.

In case of trees Importance Value Index (IVI) was calculated as sum of the relative frequency + relative density + relative dominance [12] however, the herbs only Importance Value (IV) was calculated as sum of relative frequency + relative density. Abundance to frequency ratio (A/F ratio) was determined for different species as regular (<0.025), random (0.025-0.05) and contagious (>0.05), as follows [13]. Diversity index (H) was calculated as method described by Shannon and Wiener [14], as: H= −Σ (Ni/N) log₂ (Ni/N), where ‘Ni’ is total number of species ‘i’ and ‘N’ is the number of individuals of all species in that site. Concentration of Dominance (CD) was also calculated as per Simpson [15], as: CD=Σ (Ni/N)², where ‘Ni’ and N is the same as Shannon and Wiener information index.

Dominance-Diversity (D-D) curve for trees and shrubs plotted between importance value index and species rank of trees (Figure 2) and shrubs (Figure 3). The curves indicate relationship among different species which shows their importance value of the site. The flora of Chamoli [16] and Flora of Western Himalayas [17] were consulted for the identification of species. The details of species, their uses and part used for different purposes is based on secondary data Table 1.

Figure 2: D-D curve of trees (IVI and species rank 1…n) on different sites.

Figure 3: D-D curve of shrubs (IVI and species rank 1...n) on different sites.

Table 1: Plant species, part used and uses in influenced zone of hydroelectric project. T: Tree, S: Shrub, H: Herb.

Soil characteristics

The moisture content of the soil among the sites was highest on site-I followed by site-V, site-III, site-IV and lowest on site-II. The water holding capacity was highest on site-III and lowest on site-IV. The bulk density was reported highest on site-IV followed by site-II, site-V and lowest on site-III. In the texture%, maximum proportion was contributed by sand particles in all sites, however, silt was lowest on site-I, site-II and site-IV and clay reported lowest on site-III and site-I. (Table 2) A study carried out by Kumar et al. [18] in the of this region, reported the range values of SOC phosphorus and potassium were from 0.47 to 0.68%, 9.67 to 10.56 kg ha^-1, 141.87 to 172.48 kg ha^-1 respectively. The values of SOC and potassium of present study was lower than Kumar et al. [18] which might be due to biotic pressure and disturbances created on vegetation by dam construction activities.

Table 2: Soil characteristics in different sites of submergence zone of hydroelectric project.

Community structure and distribution pattern

Site-I: On this site, 6 trees, 9 shrubs and 15 herbs were reported. Among the trees, was most dominant and least dominant. The total basal cover, frequency and density were also highest for. Other associated species shown in Table 3. The distribution pattern of and was contagiously and other species were distributed randomly except which was distributed regularly (Table 4). In shrubs, the most dominant was and least dominant. The highest total basal cover was of and lowest of. However the highest density was of. All the shrub species were distributed contagiously (Table 4) In herb layer, the highest importance value was reported of and lowest of The highest density was of and lowest of Other species reported on the site is shown in Table 5 All the species on this site were distributed contagiously, except which was distributed randomly (Table 5).

Table 3: Density (Ind. ha^-1), TBC (m² ha^-1), A/F ratio of trees on different sites in influenced zone of hydroelectric project.

Table 4: Density (ind. 25m²), TBC (cm² 25 m^-2) of shrubs on different sites in influenced zone of hydroelectric project.

Table 5: Density (ind. m²), IV (importance Value) and A/F ratio herbs on different sites in influenced zone of hydroelectric project.

Site-II: A total of 13 trees, 10 shrubs and 10 herbs were encountered on this site. The dominant tree was and least dominant. The highest total basal cover and density was reported of and respectively. Other species on the site is shown in the Table 2. The most species of trees on this site were distributed contagiously, three randomly and two regular in distribution (Table 3). In shrub layer was the dominant and least dominant. The highest total basal cover, density and frequency were reported for. The other associated species is shown in Table 5. All the species were distributed contagiously (Table 4). Among the herbs, the highest importance value was of and lowest of the other associated species on the site is shown in Table 5.

Site-III: A total of 14 trees were found, was the most dominant and least dominant Among the trees mostly species were distributed contagious, few random and only was distributed regularly (Table 3). In shrub layer, 12 species were reported, was dominant and least dominant. However, the highest total basal cover was reported of and lowest of. Among the 21 herbs, were the dominant and least dominant. All the herbs distributed contagiously. The other associated species of trees, shrubs and herbs have been shown in Tables 3, 4 and 5 respectively.

Site-IV: On this site, total 10 trees, 13 shrubs and 15 herbs reported was dominant and least dominant. In the distribution pattern and were distributed contagious, few species distributed random and were distributed regularly (Table 3). In shrub layer, was dominant and least dominant All the species of shrubs were distributed contagiously (Table 4). In herb layer, the highest importance value was of and lowest of. All the species were distributed contagiously (Table 5). The associated species on the site of trees, shrubs and herbs is shown in Tables 3, 4 and 5 respectively.

Site-V: In tree layer 9 species were recorded. The dominant tree was and least dominant. Most of the species were distributed contagiously and were distributed randomly. In shrub layer again 9 species were encountered. The most and least dominant species were and. All the species were distributed contagiously (Table 4). In herb layer, a total of 19 species were reported. Among these species the highest importance value was reported of and lowest of All the species on this site were distributed contagiously (Table 5). The other associated species of trees, shrubs and herbs is shown in Tables 3, 4 and 5 respectively.

Among the sites, the average tree density and total basal cover of trees was 728 plants ha^-1 and 25.19 m² ha^-1 respectively. In shrub layer the average density and total basal cover values were 16.45 plant 25 m² and 0.27 cm² 25 m^-2 respectively. A study carried out by Kumar et al. [19], in sub-tropical forests of the Garhwal Himalaya, reported total density and total basal cover ranged from 832 to 884 trees ha^-1 and 14.30 to 24.83 m² ha^-1 respectively. These values of density were higher than the present study, because the influenced zone is under biotic pressure. Kumar et al. [18] also conducted a study on different aspect of forest, the density ranged for trees from 260 to 380 trees ha^-1 and density for shrub ranged from 970 to 1790 shrubs ha^-1. In this study the values of density were quite lower because of higher biotic pressure especially by the villagers for their daily needs i.e., fuel, fodder, grazing and browsing animals.

Among the vegetation layers, the distribution pattern of trees was contagious, random and regular. Although contagious distribution pattern of the species was common and in shrub layer mostly species were distributed contagiously. While in herbs all the species on all sites were distributed contagiously. Odum [20] stated that contagious distribution is the comments pattern in nature and random distribution found only in very uniform environment and the regular distribution occurs where sever competition between the individuals exist [18,21]. Regular and random distribution pattern of the species reflect the high biotic pressure though grazing and lopping.

Species richness

The richness of trees, shrubs and herbs is shown in Figure 4. The species richness was maximum (14) on site-III and minimum (6) on site-I. In the shrub layer, the highest number of species was on site- IV and lowest on site-I and site-V. A study carried out by Yadav and Gupta [22] in Rajasthan, suggested that anthropogenic disturbances have adverse impact on the woody vegetation. He also suggests that species richness was higher in undisturbed forest as compared to partially disturbed forest and relatively higher in highly disturbed forest area. Kumar et al. [23] conduct a study in the same site of the dam project for conservation strategies of showed that various disturbance agents such as grazing and browsing, over-exploitation and major dam construction work in this valley is affecting the growth of . The dominant forest cover of this valley area is covered by which is the main source of villager’s requirement for fuel, fodder and minor timber which is highly disturbing by developing activities of dam and road construction work. Boring et al. [24] emphasized the positive role of mild disturbances in improving the regeneration of tree. Levin [25] also indicated sever disturbance has deleterious effect on regeneration. Khan et al [26] reported that erosion action of torrential rains on slopes can also cause a decreased in the number of seedling during the rainy season. The long history of human interaction with plants, animals and environmental factors in the mountain region has a significant impact upon the biological diversity at different levels. The topography, soil, climate and geographical location also influenced the vegetation diversity of forest. In modern time Himalayan forest ecosystems have witnessed great natural and biotic disturbances. Yadav and Gupta [22] reported that the number of shrubs reduced with increasing level of anthropogenic disturbance on the forest sites.

Figure 4: Species richness of trees, shrubs and herbs on different site in influenced zone.

Species diversity (H’) and Concentration of dominance (CD)

The diversity was highest on site-II (H=3.21) and minimum on site-I (H=2.07). In shrub layer the maximum and minimum diversity was on site-III (H=3.02) and site-V (H=2.26) respectively. In herb layer the highest diversity was on site-I (H=3.4) and minimum (H=2.92) on site-II (Figure 5). Kumar et al. [19] also reported diversity value of 2.76 for the sub-tropical forest of of this region in Garhwal Himalaya. These reported values were within the range of present study. Kumar et al. [18] carried study in forest reported diversity values H=0.846 to 1.710 for trees and H=1.943 to 2.847 for shrubs are within the ranged values of the present study. The CD ranged values for trees, shrubs and herbs were CD=0.14 to 0.29, CD=0.16 to 0.32 and CD=0.11 to 0.18 respectively (Figure 6). Riser and Rice [27] and Knight [28] ranged from CD=0.326 to 0.693 for trees and CD=0.185 to 0.719 for shrubs. These reported values of CD for trees are with the range of present study but shrub values were higher for the present study.

Figure 5: Diversity (H) of trees, shrubs and herbs on different site in influenced zone.

Figure 6: Concentration of dominance (CD) richness of trees, shrubs and herbs on different site in influenced zone.

The present study revealed that the collected data information in influenced zone is rich in vegetation and soil resources. Although the developmental activities in the dam is going on and soon after completion of project work the submergence zone will be covered under reservoir which will affect the existed pressure of villagers on influenced zone for several daily needs (fuel, fodder, timber etc). The severe pressure of villagers may affect the vegetation and further degradation of resources for villagers needs in future. The sustainability and efficiency of forest ecosystem being influenced by the hydroelectric projects in river valleys which can be restored by strengthening the knowledge on sustainable plant utilization. Therefore, local communities should aware about the submergence of valuable resources and subsequently pressure increasing in influenced zone, so community awareness may help to conserve the resource for sustainable long term out.