vol. 4, pp. 38-43
Copyright © 2011 by the Italian Society of Silviculture and Forest Ecology
doi: 10.3832/ifor0557-004

Technical Reports

Diversity pattern of vegetation in and around proposed Kotlibhel hydroelectric project along the Alaknanda River in Garhwal Himalaya (India)

V. Singh, S. Dasgupta, V. Jhaldiyal, D.S. Chauhan, N.P. Todaria

Introduction

Forests are being degraded and fragmented rapidly in the Indian subcontinent. The human influences on biodiversity and ecosystem are rapid and large, leading to frequent changes in land and resource use, increased frequency of biotic invasions, reduction in species number, creation of stresses and the potential for changes in the climate system ([9]). The loss of biodiversity actually hampers and contrasts economic development ([8]). The depletion of biodiversity is an alarming problem of the world. The rate of extinction has been enhanced by human-related habi-tat loss and climate change ([19]). Land and water resources are limited and their wide utilization is increasing, especially for countries like India, where population pressure is continuously increasing ([21]). The implications of these are remarkable, as will lose crucial life-supporting systems through the loss of important habitats, undermining rural livelihoods because of the degradation of natural resources on which people depend. It shall also diminish economic opportunities, as options for developing medicines and foods will reduce and the natural resource base for tourism will be damaged. Transfer of forest and agricultural lands to industries, hydroelectricity and thermal electricity projects, etc. are current investments. But what do we do to compensate the loss of the agriculture and forest? This is important in a context where the 70% of the country population lives in villages and depends on agriculture and forest for his livelihood. In addition, social and environmental aspects also need attention. Everybody knows why and to what extent forest resources are essential to protect life on earth. Therefore, documentation on current habitat structure and resource distribution and richness is necessary to estimate their loss. Biodiversity is also being depleted because of legal and illegal trade in economically and medicinally important species ([19]). Keeping in view the necessity of documentation on flora degradation before now, a study was conducted in the project area of Kotlibhel hydroelectric power project 1B (KHEP-1B) in Uttarakhand. The project is likely to submerge about 502.35 ha of land, classified as “Submergence zone”. Some of the areas around the reservoir are also going to be disturbed due to different project related activity and was classified as “Influence zone” The present study deals with the diversity pattern and vegetation characters of the Influence and Submergence zone of the KHEP-1B.

Methodology

To analyze plant diversity, a study was conducted in the area of about 350 km2 along rivers Alaknanda and Ganga between Srinagar and Devprayag. The area covers a stretch of about 30 km long and 7 km wide.

The vegetational analysis was conducted since June 2005 to Feb 2006. The study area was divided into two subareas: “Influence zone” (IZ) and “Submergence zone” (SZ) along the reservoir, as proposed by the Dam authority. The area subjected to submersion up to full reservoir level (FRL - approx. 325 m a.s.l.) was considered as submergence zone and the area along the reservoir up to 7 km radius around the reservoir was considered as influence zone. Some 8 transects were analyzed in the entire study area: Supana-Sundari, Switpul-Swit, Bhallagaun-Hakgaun, Bagwan-Golta, Mullagaun-Kothi, Gunkhal-Semi, Dhanchera-Pali and Saud- Sariyakhal. Each transect was 1500 m long, from the river water level along an increasing altitudinal gradient (Fig. 1). Transects were spatially distributed so as to minimize the autocorrelation among the vegetation. Along each transect, six circular plots (each of 10 m radius) at 200 m intervals were sampled. Circular plots were used for sampling due to undulating surface of the study area. Trees in circular plots were enumerated.

Fig. 1 - The study area.

Within each 10 m radius plot, a nested circular plot of 5 m radius was sampled for recording shrubs, whereas four nested circular plots of 1 m radius were established for herbs analisys. Herbs were recorded by point-intercept method for their proportional representation in the area. In order to prepare a checklist and best represent the species from the area, an intensive search was made by re-tracing belt transects in three different seasons.

Species characterized by short stature, including annual or biennial herbs, and by spiny structures (thorns and spines) were classified as shrubs. Herbs included shade- loving, annual, biennial or perennial, herbaceous species. Trees with cbh (circumference at breast height, i.e., 1.37 m above the ground) > 31.5 cm were individually counted in the 10 m radius plot. Herbarium sheets of species which could not be identified in the field were prepared, and identified later at the Department of Botany, HNB Garhwal University. Taxa names were assigned after the nomenclature proposed by ([n/a]).

Frequency, density, abundance and their relative values for each species were obtained using the equations reported below ([11]). The Important Value Index (IVI) for different species was calculated as sum of relative frequency (RF), relative density (RD) and relative abundance (A) of each species as follows (eqn. 1):

$$IVI = RF + RV + A$$

AF ratio for different species was determined for eliciting the distribution pattern in terms of regular (AF<0.025), random (AF=0.025-0.05) and contagious (AF>0.05), as follows ([4] - eqn. 2):

$$AF = Abundance / Frequency$$

The Shannon’s ([17]) H’ and Simpson’s ([18]) D diversity indices were independently obtained as follows (eqn. 3, eqn. 4):

$$H^{\prime} = - \sum{p_i\;ln(p_i)}$$
$$D = \sum{p^{2}_{i}}$$

where p i represents the proportional abundance of i-th species in any given transect.

Species richness (SR) was calculated following Margalef ([12]):

$$SR = {{S-1}\over{ln(N)}}$$

where S is the number of species and N the total number of individuals of all species.

Results

Vegetation analysis

In tree layer of IZ, maximum density (36.4 plants/ha) and frequency (95.8 %) was observed for Haldinia cordifolia followed by Pinus roxburghii (density: 33.1 plants/ha; frequency: 89.6 %) and Holoptelea integrifolia (density: 29.2 plants/ha; frequency: 77.1 %). The IVI of different species ranged between 1.43 to 71.88 in IZ. Within SZ highest density (33.8 plants/ha) was recorded for Lannea coromendelica and lowest density (1.3 plants/ha) was recorded for Celtis australis, Ougenia ooginansis and Terminalia chebula. In this zone maximum frequency (31.3 %) was also found for Lannea coromendelica followed by Pinus roxburghii (29.2 %) and Holoptelea integrifolia (27.1). The IVI values of different species within SZ were between 1.73 to 58.77 (Tab. 1).

Tab. 1 - Vegetational characteristics of tree species in the Influence and Submergence zones of the study area. (NR): species present but not recorded within sampled quadrate; (Abs): absent. For the list of additional species found outside the sample plots, see Tab. SM1 in the Supplementary Material.

In the IZ shrub layer, Murrya koenigii was the dominant species with maximum frequency (100%), density (589.2 plants/ha) and IVI (14.5), while in the SZ Ficus hederacea was the dominant shrub with highest frequency (89.6 %), density (844.0 plants/ ha) and IVI (35.14). Minimum density (8.0 plants/ha) was observed for Eupatorium adenophorum and Rhus parviflora. Lowest frequency (4.2 %) was also observed for Eupatorium adenophorum, Rhus parviflora and Urtica dioica (Tab. 2).

Tab. 2 - Vegetational characteristics of shrub species in the Influence and Submergence zones of the study area. (NR): species present but not recorded within sampled quadrate; (Abs): absent. For the list of additional species found outside the sample plots, see Tab. SM2 in the Supplementary Material.

In the IZ herb layer, Chrysopogon aciculatus showed highest density (5506.9 plants/ha) followed by Cynadon dactylon (3781.8 plants/ha) and Evolvulus alsinoides (3416.9 plants/ha). These species have also maximum frequency (100 %) among all herb species. The observed IVI for herb species was between 1.59 to 16.52 in this zone. On the other hand, in the SZ highest density (5540.1 plants/ha) was calculated for Desmodium triflorum followed by Heteropogon melanocarpus (5490.3 plants/ha) and Heteropogon controtus (5457.1 plants/ha), whereas maximum frequency (96.4 %) was recorded for Heteropogon melanocarpus and lowest frequency (13.5 %) for Digitaria ciliaris. The observed IVI value in this zone ranged between 2.87 to 14.25 (Tab. 3).

Tab. 3 - Vegetational characteristics of herb species in the Influence and Submergence zones of the study area. (NR): species present but not recorded within sampled quadrate; (Abs): absent. For the list of additional species found outside the sample plots, see Tab. SM3 in the Supplementary Material.

Distribution pattern

The abundance/frequency ratios (A/F) obtained showed that most of species were contagiously distributed in both IZ and SZ. In the tree layer, 84.5 % species were found in contagious pattern within IZ and 15.4% were randomly distributed. For shrubs in the IZ, 50% species were in contagious and 50% in random distribution, while in SZ 95.8% species were in contagious distribution and 4.2 % were in regular distribution pattern (Tab. 1, Tab. 2, Tab. 3).

Diversity

Among all vegetation layer of IZ and SZ, the maximum number of species was encountered for the herb layer of IZ (41) and the minimum (20) for the tree layer in the SZ. Shannon diversity (H’) was highest for the herb layer of IZ (3.561) and minimum for shrub layer of the SZ (2.370). The Simpson diversity was ranging between 0.034 to 0.138. Margalef index showed maximum value for the herb layer in the IZ (4.8) and minimum (3.2) for shrub layer in the SZ (Tab. 4).

Tab. 4 - Diversity indices and species richness in the both zone of study area. IZ: Influence Zone; SZ: Submergence Zone

Shannon and Simpson diversity indices for tree layer did not show significant differences between IZ and SZ after t-test. On the other hand, Margalef index for trees showed significant difference between these two zones (P<0.001, df. 13). Shannon diversity and Margalef indices for shrubs were significantly different bewteen IZ and SZ (P<0.001, df 12), while no significant differences were detected for Simpson diversity index. Herbs also showed the similar trend as shrubs of IZ and SZ.

Discussion

Disturbance has become a widespread feature in most of the forest all over the Himalaya ([20]). Knowledge on ecological process and biotic pressure may help in understanding the persistence of long-lived plant communities. Tree density observed in this study is lower than that recorded for mid-elevational forests in Central Himalaya ([7]), but similar to those reported (5 to 325 plants/ha) by Sanjeev et al. ([15]) in a micro watershed area of Mussoorie in Garhwal Himalaya. Similarly, shrub densities in this study are lower than those reported by Hussain et al. ([5]) but similar to what observed by Khera et al. (2001). Furthermore, Negi et al. ([13]) reported herb density in Garhwal Himalaya similar to that found in the present study.

The changes in the dispersion patterns may reflect the reactions of species to disturbance, as well as to changes in the habitat conditions ([14]). The analysis of species’ distribution pattern based on the A/F ratio indicated that most of the species of both zones were distributed in contagious pattern. Joshi & Tiwari ([6]) and Bhandari et al. ([3]) also reported a fairly similar distribution pattern of woody vegetation in different parts of Garhwal Himalaya.

Shannon species diversity (H′) and concentration of dominance (cd) of the present study sites are more or less similar to the values reported by Kunwar & Sharma ([10]) in a comparative study between two community forests in Dolpa district of mid-west Nepal. These values were comparable with those reported for the Chir pine forest in Garhwal Himalaya ([3]). The low diversity oberved in this investigation may be interpreted as due to greater anthropogenic pressure.

Species richness in out study showed higher values for ground vegetation (herbs), followed by shrubs and trees. Khera et al. ([7]) also found the same pattern of species richness. Hussain et al. ([5]) also found overall 63 tree, 56 shrub, 90 herb and 21 grass species in Kumaon Himalaya. In a comparative study between Panchayat and Reserve forest in Garhwal Himalaya, Negi et al. ([13]) reported a similar richness trend (Herb>Tree>Shrub). Saxena & Singh ([16]) have also recorded high species richness (4 to 22) and diversity (0.74 to 3.10) for shrub layer in Kumaun Himalaya. Influence zone showed a higher species richness in our study, while Adhikari et al. ([1]) found higher richness in the Submergence zone of the Tehri hydroelectric dam in Uttarakhand.

Conclusion

The vegetation of the study area is important for sustaining the livelihood of local people. The present study suggests that the influence zone has the maximum species diversity and richness. Diversity was high where the dominance of canopy species was major and low near agricultural fields or on disturbed sites. The vegetation composition of both zones was found almost in similar pattern, though species richness was larger in the Influence zone. Hence, it may be hypothesized that after construction of proposed hydropower project there may be negligible effect on the species richness of the surrounding vegetation, but definitely a significant portion of the vegetation is going to be lost for ever. The change in landuse of riverine belt might also change the micro habitat requirement of many species. This of course require detailed investigation in order to conclude species specific impact of the proposed hydropower project.

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