Theses and Dissertations

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Author: search.filters.author.Ramesh, C.Start date: 2020

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    Influence of invasive plant species on native plant-flower visitor interactions in a scrub forest of Anaikatty, Nilgiri Biosphere Reserve
    (Wildlife Institute of India, Dehradun, 2025) Akilan, K P; Ramesh, C.; Gautam, Ritesh Kumar; Karunakaran, P.V.
    Invasive alien species are one of the top five drivers of biodiversity loss globally. Invasive alien species are known to cause changes to the biotic interactions in the invaded regions. Pollination is an important limiting process in the life cycle of plants and the pollinators potentially mediate the process of invasion through novel interactions. Invasive plants can have an impact on the native plant-pollinator interactions. 2. I studied the influence of invasive plants on the native plant-flower visitor interactions in the scrub forests of Anaikatty, Nilgiri Biosphere Reserve. I determined the change in flower visitor diversity along an invasion gradient. I also compared the visitation between native and invasive plants, by looking at the difference in composition of insect interactions with native and invasive plants. I used 20 min zigzag walks in 26 plots across three months looking at insects interacting with flowers. I also estimated the density of flowers in each plot. 3. I used generalised linear mixed effects models to draw the relationship between insect richness and the proportion of invasive flowers, and between number of visits and proportion of invasive flowers. To compare the difference in composition of flower visitors between the plant species, I performed permutational multivariate analysis of variance (PERMANOVA) with bray-curtis dissimilarity index. 4.I observed 191 unique plant-flower visitor interactions of a total of 813 plant-flower visitor interactions, formed by 68 insect visitors and 28 flowering plants. Native plants, Sida cordifolia (25%), Tephrosia purpurea (20%) and Glycosmis mauritiana (13%) and invasive plants Parthenium hysteriphorus (8%) and Ageratum conyzoides (6%) formed majority of the interactions. Hymenoptera and Lepidoptera are the insect orders with the most number of interactions. 5. The richness and number of flower visitors increase with increasing flower density. The richness and number of flower visitors show a negative relationship with proportion of invasive flowers. The composition of visitors is significantly ifferent among all native flowers and between native flowers and invasive flowers.6.This is the first study in the Nilgiris Biosphere Reserve looking at plant-flower visitor interactions in wild flowers, with a focus on the influence of invasive species. Visitation of insects to a plot has a weak negative relationship with proportion of invasive species, in this context. This study sets the baseline for future studies that could look at explaining the patterns seen, looking at relationship between the functional diversity of flowers and insects.
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    Assessing the Impacts of Road Network on Wildlife Corridors and Mitigation Measures in Assam : Transportation Against Animal Corridor
    (Wildlife Institute of India, Dehradun, 2021) Borgohain, Roshme; Habib, Bilal; Ramesh, C.
    Protected Area Networks (PA) and Conservation Areas (CA) are very essential for ensuring the conservation of wildlife. However, the connectivity among these protected areas is much more important to ensure the viable population of species. Furthermore, the increase in infrastructural development and human encroachment leading to the fragmentation of forests and the natural habitat of wildlife species. The wildlife corridors are the essential structures to connect the fragmented areas, ensure the viability of the isolated population, restores the genetic variations, corridors also increases the habitat diversity in the two habitat patches that it connects, it provides a passage for migration and also acts as an escape route in cases of fire in one patch. Overall wildlife corridors are structures that are important for conservation. Although these protected areas were not well connected the corridor structures help to maintain the continuity of the area. The state falls under North-East India Biogeographic zones under the Province North-East-East-Brahmaputra Valley (9B), (Rodgers and Panwar 1998). In Assam, there are seven National Parks and twenty Wildlife Sanctuaries occupying the area of 3925+ sq. km, where two are designated as World Heritage site (WHS) which is the highest designation given to the protected area. Out of twenty-seven protected area in Assam, fifteen were bifurcated by road networks and there are total eleven corridors, connects the protected areas, eight corridors were cut at multiple places by roads. These connections of the corridors are essential to maintain the contiguous landscape, which is further essential for maintaining the integrity of the WHS. In this study, I have tried to look at the current status of the wildlife corridor portion bifurcated by the road networks in Assam. The objective of the study is 1) What is the extent of different types of road networks concerning PAs and corridors in the State of Assam? 2) What is the land use pattern near the corridor bifurcated by the road? 3) Characterize the current status of the corridor sites impacted by the road network.
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    Montane Lizard in a Mosaic Landscape: Effect of Tea Plantations on Anamalai Spiny Lizard (Sales anamallayana)
    (Wildlife Institute of India, Dehradun, 2021) Devrajan, Anjitha; Ramesh, C.; Das, Abhijit
    The Anamalai Spiny Lizard (Salea anamallayana), an agamid lizard endemic to southern Western Ghats is reported to use shola and tea plantations of Kannan Devan hills of high ranges of Kerala. The Western Ghats has experienced extensive habitat destruction and modification since a very long time and the lizards are highly affected by habitat modification which in turn affect their fitness and survival. In this study we investigated the effect of habitat modification on morphology, population and habitat association in Salea anamallayana in the shola forests of Eravikulam National Park and surrounding tea plantations. The study was conducted from February 2021 to May 2021. Line transect method was used to study density and Visual encounter surveys for collecting data for basking habitat use and morphology. Surveys were conducted from 9 am to 2 pm since the lizard was more active during the time period. Shola and plantation are structurally very different. Shola was divided into shola close to plantations and shola away from plantation. Plantation was classified according to the proximity to shola and presence of shade trees. The density was found to be more in shola (27.59±6.79/ha) compared to plantation (8.63 ±2.21/ha). In plantations, the density was influenced by proximity to shola and presence of shade trees. Density is more in plantations in close proximity to shola (20.91±4.51/ha) compared to plantations away from shola (2.85±1.37/ha) and the lizard was present only where the shade trees were planted. The sex ratio was biased towards male in plantations (100:14) and it improves in shola close to plantations (100:33) and further improves in shola away from plantations (100:50). The body condition of male lizards was poor in plantations compared to shola away from plantations (t = 2.57, df = 14.17, p-value = 0.021). The males do not differ in other morphological variables across the habitats. Body condition of males is better than females (t = -2.19, df = 23.80, p-value = 0.037). The basking habitat use is in proportion to habitat availability. The microhabitat use varies across shola and plantation. Average perch height and perch diameter is more in plantation and average canopy cover is more in shola. More diverse perch surface is available and used in shola compared to plantation. The average body temperature is high in plantation compared to shola and the body temperature is directly proportional to atmospheric temperature and substrate temperature. There is no significant difference in Flight Initiation Distance (FID) between shola and plantation. FID is inversely correlated to substrate temperature.