Theses and Dissertations
Permanent URI for this communityhttp://192.168.202.180:4000/handle/123456789/1
Browse
36 results
Search Results
Item Influence of Canopy Gaps on Mangrove vegetation and Crab communities in the Andaman Islands(Wildlife Institute of India, Dehradun, 2025) Sengannan, Perarivalan; Prabhakar, N.Small-scale, infrequent disturbances enhance habitat heterogeneity in the landscape and promote diversity. Canopy disturbances caused by lightning strikes in mature mangrove stands modify environmental factors such as canopy cover and light intensity. Response of mangrove vegetation and crab communities to such canopy gap formation remains the least investigated aspect among ecologists. The canopy gaps were stratified based on the recent and recovering status of vegetation recruitment along with gap age, and an intact forest plot was sampled as a control treatment. The result shows that canopy opening has a significant effect on water temperature, and it has a profound influence on structuring vegetation and the crab communities in mangroves. Seedling and sapling density was 2-fold higher in canopy gaps than intact forest, and higher sapling survival was witnessed in canopy gaps. 28 species of crabs were recorded collectively from all treatments. Crabs of the family Ocypodidae were found in large proportion in canopy gaps, as the organic matter from microalgae and bacteria is their primary food base. Overall, canopy gaps in contiguous mangrove habitats are a hot spot for crab diversity and serve as a regeneration niche for seedlings and saplings by creating structural heterogeneity in the landscape. It suggests that small-scale natural disturbances, such as canopy gaps, promote habitat complexity and crab diversity.Item Patterns of Ant Species Richness and Composition in Deccan Inselberg-Matrix systems of Karnataka(Wildlife Institute of India, Dehradun, 2025) Sujay G; Adhikari, B.S.My study looked into patterns of ant species richness and composition of Deccan inselbergs and surrounding human altered matrix (natural habitat, mango plantation) in Ramanagara taluk, Karnataka, in a bid to recognize their ecological and conservation potential. Ants were chosen as the model taxa, due to their micro-habitat specificity, to better understand environmental gradients and related faunal associations at different scales. Pitfall traps were used as the sampling methodology for ants, and habitat variables were collected at each trap; ants were identified until morphospecies level within respective genera. Data analysis included understanding habitat differences, patterns of species richness and composition, and relating these aspects. The results showed that inselbergs were distinct in terms of habitat structure as compared to the matrix, with the latter showing less vegetation complexity (lesser in mango plantation). While matrix and inselberg showed comparable levels of ant richness, delving deeper it was seen that natural habitat within matrix showed significantly higher richness as compared to the species poor, uneven mango plantation ant assemblage. Similarly, inselbergs and matrix showed similar average composition of their respective ant communities. However closer inspection showed that natural habitat and plantation, when compared separately with inselbergs, showed compositional dissimilarity to greater magnitude. Habitat variables, while statistically significant in their relationship with patterns of ant composition and richness at finer scales, explained a minimal amount of total variation seen in both. Inselbergs, as understood through this study, are not “barren wastelands”, but on the contrary are important reservoirs of regional diversity. In light of rapid human alteration of the surrounding matrix and threats like quarrying, invasive species, inselbergs and the low lying natural habitat need to be given greater conservation importance. This study is hopefully just one of many that are required to further assess the conservation and ecological potential of these amazing ecosystems.Item Diversity and distribution of Moth Assemblages Along Altitudinal Gradient in Gangotri Landscape, India(Wildlife Institute of India, Dehradun, 2015) Sanyal, Abesh Kumar; Uniyal, V.P.This study intends to document the extent of moth assemblages that exist amongst various habitats in a typical Western Himalayan altitudinal gradient in Gangotri Landscape Area (GLA). In this study, using the elevation gradient as natural experiment, the faunal structure and diversity of the moth assemblage featuring all the major macro and micromoth families as well as relationships between moths and their biotic and abiotic environments were explored. Specific objectives of the study were: (1) Documenting and prepare taxonomic inventory of rich moth fauna of Gangotri Landscape Area; (2) To assess diversity and distribution of moth assemblages among different elevations and vegetation types of Gangotri Landscape; (3) To analyze the influence of altitude, seasons, vegetation types and anthropogenic disturbance factors on moth assemblages; (4) To investigate morphometric changes (body size and proportional body parts) in moths along altitudinal gradient. The study was conducted in Gangotri Landscape Area (GLA), a vast conservation network in the North-Western part of Uttarakhand, in district Uttarkashi. A total of 670 morphospecies belonging to 22 families and 356 genera were collected during entire sampling period from 2008-2012. This study is an important step towards better understanding of a long-neglected but diverse and charismatic herbivorous insect assemblage in Himalayan temperate altitudinal gradient.Item Plant diversity gradients along the Himalaya: A comparison between the east and the west(Wildlife Institute of India, Dehradun, 2018) Kumar, Suresh; Rawat, G.S.; Price, TrevorPatterns and causes of latitudinal and elevational diversity gradients have gained increasing attention in the field of macroecology. A monotonic decline in species richness from low to high latitudes and elevations was widely accepted as the common pattern for a long time. However, reviews of the available literature on patterns of species diversity along elevational radients show that species richness often does not monotonically decline with elevation. In this thesis, I analyse the elevational and latitudinal patterns of plant species richness across the Himalaya.Item Study of the flora of Sathyamangalam Tiger Reserve, Southern Eastern Ghats, India(SACON, 2019) Prakash, L.; Balasubramian, P.Sathyamangalam Tiger Reserve (latitude II" 29' IS" to Il u 43' II" N and longitude 760 50' 69"to 77 0 27' 22" E) forms a major biodiversity rich area in Eastern Ghats. India with a mixture of both indigenous and exotic species. Sathyamangalam Tiger Reserve bas got a high diversity of flora and fauna owing to its unique location which is a confluence of two distinct geographical regions, namely the Eastern Ghats and Western Ghats. The Tiger Reserve is rich in floristic diversity and 14 different types of forests from dry scrub to West-coast semi evergreen forests occur here. A threatened tree species, Sandal (Santalum album) occurs predominantly in the dry forests of Sathyamangalam Tiger Reserve. The study area has some major perennial river systems such as Moyar and Bhavani. The major indigenous tribal communities of this region constitute Irulars, Ooralis. Kurumbas and Soligars. A total of 17 intensive field exploration trips were conducted covering different seasons between August 2014 to March 2017Item Diversity and Distribution Pattern of Moths (Lepidoptera : Heterocera) with special emphasis on family noctuidae in Askot Wildlife Sanctuary, Uttarakhand(Wildlife Institute of India, Dehradun, 2021) Bandyopadhyay, Uttaran; Uniyal, V.P.This study has been planned to prepare a consolidated inventory of moth fauna of one of the most diverse protected areas of Uttarakhand, the Askot Wildlife Sanctuary, to assess the seasonal variation of a specialist group, the Noctuidae. The study also aimed to determine the effects of the environmental factors that govern the distribution as well as assemblage pattern of this particular family and targeted to identify the species with potential to indicate overall quality of the different habitats altitudinally which in term will contribute in future species conservation strategies.Item Avian Species selection in Urban Habitats: A study in Coimbatore, India.(SACON, 2013) Rajini, J.; Azeez, P.A.Survival of a species is closely associated with changing habitats. We studied this in the context of urbanization that brings massive changes in the landscape. The study is contextual in view of high rates of conversion of natural landscapes into urban areas. With the ascent of urbanization, many species disappear while some species become abundant. The present study investigated avian species and their distribution along a rural-urban gradient of the Coimbatore city - a fast growing city in Tamil Nadu, India. The study was taken up to explore the factors that affect the distribution of avian species across an urbanisation gradient and to identify survival strategies adopted by avian species in urban areas.Item Avifaunal Diversity of the Andaman Islands and their Conservation(SACON, 2010) Rajamannan, M.A.; Vijayan, LalithaBiodiversity hotspots in the world are chiefly tropical region is featuring high concentration of endemic species and has claimed ha lf of the world's terrestrial species, if all hotspot's are combined. These natural habitats are under threat now due to habitat loss and destruct ion. Consistently the islands, a small body of landmass are having a major role of its high endemism in the world. Nevertheless, the increasing demands on resources in the islands have resulted in their ecosystems being severely threatened and facing in its extreme habitat destruction. For example over 12.1 % of all bird species in the world are threatened with extinction today in which the majority of these are found in tropical forest and islands. There is disputing that global biodiversity is declining, but accurate measures are very hard to come by. Bird’s, the best known major group of organisms and just one component of biodiversity and far from the most significant in species numbers or biomass can help us to understand the problems and piece together the solutions, where the maintenance or restoration of the biological integrity of urban and Sundarbans areas must begin with a comprehensive study of the links between biota and land use. In this context bird communities are often used in investigations of habitat changes as the best indicators of the environment. Though the Indian mainland harbours rich avifauna diversity the Andaman and Nicobar Islands. The information on community structure and general bird ecology of these islands are little known and very few attempts have been made to study the bird community along their island distribution. Hence, the present study was initiated with the major objectives to: i) document the avifaunal diversity and status in different islands/vegetations, ii) observe the bird species distribution pattern in the Andaman Islands with their biogeographical importance, iii ) study the nested·subsets of the birds in different outer islands in terms of their presence/absence which will be providing a risk assessment of the extinction probability of the various species' populations isolated on the islands of fragmented habitat, and iv) understand the insular biology of the endemic and threatened species in Andaman Islands as of baseline information for their conservation.Item Communities of small mammals and small carnivores in the Teesta River Basin, Sikkim Himalaya, India(SACON, 2008) Thapa, Jaya; Bhupathy, S.Differences in communities of plants and animals along environmental gradients have been the basis for many ecological theories. Among the first geographical patterns to be recognized in ecology was the climatic gradient in body size of animals, later formalized as the Bergmann 's rule. Latitudinal and altitudinal gradients in species richness are other geographical patterns that have long since been recognized. The different nature of gradients and the ecological factors that cause such gradients have both been subjects of considerable debate in recent decades. Community structure in animals can also be influenced by various factors such as vegetation, biological constraints and historical factors, which may not form gradients. In this dissertation I have examined the in fluence of altitude and vegetation on communities of small mammals and small carnivores in the 11 Himalayan mountain ranges in the Indian State of Sikkim. The sharp altitudinal gradient from 230 m to 8586 m and the variety of vegetation types in this small state,. The overall goal of this study was to examine the influence of altitude and vegetation on the organizalion of the small mammal community in Sikkim Himalaya, with respect to its species richness, composition. distribution, and abundance. The specific objectives of this study were: a. To test the hypothesis that the body weight of murid rodents and shrews should respond to the sharp altitudinal gradient; b. To identify the pattern of variation in the community structure of the murid rodents and shrews along an altitudinal gradient and among different vegetation types; c. To test the hypothesis that murids and shrews differ in microhabitat use in a manner that is consistent between vegetation types; and d. To examine the influence of altitude and vegetation types on the composition and relative abundance of the small carnivore community, as well as their diet. This study was carried out in the North and South Districts of Sikkim in the Teesta River Basin, between 230 m to 3700 m altitude, from June 2003 to April 2004 and from May 2005 to December 2005Item Bird communities and their distribution pattern along the elevation gradient of Teesta Valley, Sikkim(SACON, 2008) Acharya, Bhoj Kumar; Vijayan, LalithaStudies on ecology of local communities are important for understanding environmental problems and planning area-based conservation management (Simberloff, 2004). Community composition, species richness and diversity of birds in five different elevation zones of Teesta valley, Sikkim were studied from June 2003 to March 2006 using point count sampling method. A total of 329 species of birds (299 during regular quantitative sampling and 30 during. opportunistic observations) belonging to 44 families was recorded in the Teesta valley during the study period. The study shows that Teesta valley harbors high diversity and abundance of birds. Broadleaved vegetation, situated at mid-elevation region, is the most diverse zone as compared to tropical, coniferous or alpine vegetation. Species accumulation curves based on number of point counts indicated that most of the species were detected in all the zones. Species richness (observed and estimated) was the maximum in zone II, whereas density, abundance and diversity were the maximum in zone iii. The species-abundance pattern of birds followed truncated log-normal distribution for total bird population as well as for all the zones except zone II which did not fit to any models. Bird data showed the presence of both types of species, exclusive (restricted to one elevation zone) and generalists (present in two or more zones), in the Teesta valley. Out of the total species observed (329), 156 (47.4%) were exclusively recorded in one specific elevation zone. Only three species, namely Blue Whistling Thrush, Greenish Warbler and White-capped Water Redstart occurred in all the five zones.