M Sc Dissertation(WII)
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Item Golden Langur Distribution, Habitat Selection and Corridor – Connectivity: Assessing Patterns and Addressing Threats(Wildlife Institute of India, Dehradun, 2024) Basumatary, Rishi; Nath, Anukul; Gopi, G.V.; Chetry, DilipThe Golden Langur (Trachypithecus geei), is an endangered colobine primate, confined to fragmented forest patches in western Assam, India, and south-central Bhutan. The golden langur has experienced severe habitat loss and fragmentation due to ethnolinguistic and religious conflicts between the late 1980s and late 1990s, followed by developmental activities in western Assam. The primary threat faced by the golden langur in India are the rapid reduction of its natural environment and the fragmentation of its habitat. Factors such as a limited population size, the breakdown of meta-population dynamics, and unique traits of a species often make a population in a fragment more likely to experience local extinction. Due to the significant decline in the range of Golden langur in both Bhutan and India, as well as the ongoing destruction of their habitat in India, it is imperative to safeguard even the smallest local populations. The populations residing in these fragmented Reserved Forests and Proposed Reserved Forests are effectively confined, separated from the primary breeding population, and susceptible to demographic and genetic influences. The objective of this study is to understand the current distribution, suitable habitat, and connectivity of corridors for the severely fragmented southern population of golden langur in India. Additionally, the study aims to examine the specific habitat preferences and demographic patterns of langur groups, as well as evaluate the threats that this fragmented population faces. The study was carried out in nine fragmented forest patches that includes Wildlife Sanctuary (WLS), Community managed RF (CMRF) Reserved Forest (RFs), and Private Rubber Plantations and Adjoining Forests (PRP_AF). In the present study, a total of 123 trails, ranging from 0.4 km to 1.6 km, were walked, covering a total distance of 118.72 kilometers. During these surveys, a total 51 troops (including 8 multi-male multi-female troops and 5 all-male groups), consisting of 499 individuals were encountered. The mean group size and age-sex ratio between different protected regimes that include wildlife sanctuary (WLS), community managed RF (CMRF), reserved forest (RF) and private rubber plantation and adjoining forests (PRP_AF) were compared. The overall mean group size of the langur was 9.78 (± 0.69 SE). Of the total 499 individuals, 13.22 % comprised of adult males, 41.88 % adult females, 16.83 % sub-adults, 10.02 % was juveniles and 18.03 % was infant. The average age-sex ratio of adult males to adult females was 0.287 (± 0.04 SE), juveniles to adult females was 0.224 (± 0.02 SE) and infants to adult females was 0.407 (± 0.04 SE). The infant to female ratio was found higher in wildlife sanctuary as compared to other reserved forests in the study area. The current study revealed that approximately 883 km² of the area is highly suitable for the endangered golden langur. Percent forest cover was found to be the most important variable in determining the probability of occurrence of golden langur in India. The corridor connectivity analysis showed high conductance for corridors namely Bamungaon and Khoragaon RF. Similarly, the connectivity is permeable between Kakoijana and Bamungaon. Other corridors identified in the study are Bhumeshwar Hill, Nakati RF and Kakoijana RF. On the other hand, there is high conductance among corridors of Chakrashila WLS and Nadangiri RF. Additionally, fine scale habitat selection study showed that tree species diversity, canopy cover and food plant density are the key in determining the occurrence of golden langur. In the last six years, a total of 56 mortality and injury incidents were reported from the study area which include 45 deaths and 11 injuries. Electrocution accounted for 29 cases, especially near forest edges, while 21 road accidents occurred mainly on national and state highways, as these roads are broader and have higher traffic volumes compared to village and town roads. Most accidents happened in the corridors between Chakrashila WLS-Nadangiri RF and Kakoijona RF-Bamungaon RF. Specific measures need to be taken to minimize electrocutions and road accidents of golden langur in the region. Mitigation measures like insulating electric lines and road safety protocols such artificial canopy bridges (ACB) and metal animal overpasses (MAOP) are essential for safe and easy movement along these corridors for the golden langur's survival in fragmented habitatsItem Influence of Forest Cover on Fruit and Frugivore Richness and Abundance in Southern Western Ghats(Wildlife Institute of India, Dehradun, 2021) Takorbhai, Patel Zankhnaben; Page, Navendu V.; Kumar, AmitHabitat fragmentation is a pervasive threat to ecosystem processes like seed dispersal, which is vital for biodiversity maintenance in tropical forests. Habitat fragmentation negatively impacts the richness, abundance and composition of plants and animals, thereby disrupting the interactions between them, with cascading impacts on biodiversity. However, the remnant fragments continue to harbour biodiversity. However, it is critical to determine the functional value of the fragments in terms of fruit resource diversity and availability and prevalence of frugivores across different size classes. To this end, I conducted the study in the Valparai plateau and adjacent contiguous patches of rainforests in the Western Ghats. I first determined the organization of plant-seed disperser community and identified key frugivores and plants in the landscape using network analysis. Using mixed models and the recently developed Joint Species Distribution Modelling approach called HMSC (hierarchical modelling of species communities), I investigated 1) the relationship between the amount of forest cover and richness of fruiting plants across different seed size classes, 2) the relationship between the amount of forest cover and availability of fruit s across different seed size classes 3) the relationship between richness and presence of all the avian frugivores and, amount of forest cover, and richness and availability of fruits. I recorded the frugivores and fruiting plants from 33 trails distributed in 12 fragments and 2 sites in contiguous area during four months of sampling. I also recorded plant-frugivore interactions. I documented 49 species of fruiting plants and 17 species of avian frugivoresItem Impact of Habitat Fragmentation on Plant -Frugivore Interactions in Lowland Tropical Forests of Upper-Assam North East(Wildlife Institute of India, Dehradun, 2019) Jain, Abir; Page, Navendu; Rawat, G.S.Tropical forests are considered the storehouse of biodiversity. One of the key ecosystem processes that governs the diversity of tropical trees is seed dispersal. Tropical forests globally face deleterious effects of habitat fragmentation such as loss of habitat area, reduced species richness and altered community composition. Forest fragmentation can also alter mutualistic interactions between plants and seed dispersers, disrupting key ecosystem processes like seed recruitment and regeneration. In the past century, logging, habitat conversion to tea plantations and agricultural fields have resulted in the fragmentation of the last remaining lowland tropical forests of Upper Assam in north-east India. However, these isolated forest fragments might also hold a great potential to preserve native biodiversity distributed across patches. There is paucity of information on impacts of habitat fragmentation on plant–seed disperser interactions from Asia. 2. In this study, I investigate the impacts of habitat fragmentation on plant-disperser communities. The impacts were assessed at the level of the community and at the level of species guilds (body size, habits, and families). 3. The plant-frugivore interactions were recorded by systematically walking 27 trails across two habitat categories: contiguous forest sites (n=2) and fragmented sites (n=4) over the duration of four months. Spot census was carried out to record interactions between a fruiting plant and frugivores. Fruit handling behaviour of birds and fruit crop size of plants were also recorded. Plants and seed dispersers that interact with one another, forms a network. 4. I constructed presence-absence networks for each habitat type, which represents all plant-seed disperser interactions recorded in the contiguous forests and the forest fragments. ‘Network-level’ properties were obtained to understand the influence of fragmentation on plant-seed disperser communities and ‘Species-level’ properties were obtained to assess the roles of species guilds in each of these communities. 5. Although, the networks for contiguous and fragmented forests were similar in terms of total number of mutualist species participating in its organisation, their composition was different. On an average, frugivores had one plant partner more in the contiguous forest, while plants had three frugivore partners more in the forest fragments.Item Impact of Habitat Fragmentation on Diurnal Squirrels in Lowland Tropical Forests of Upper Assam North-East India(Wildlife Institute of India, Dehradun, 2019) Sumashini, P.S.; Nair, Manoj V.; Qureshi, QamarThe effect of forest fragmentation on a set of ecological parameters, namely, species richness, densities, activity patterns, vertical space use for foraging, diet and nesting characteristics of diurnal tropical tree squirrels was investigated in five forest fragments (three in <5 km2 and two in 20-30 km2 size classes) and compared against two large forest tracts (>100 km2) in upper Assam, north-east India. The study focused on the four common diurnal squirrels, Malayan Giant Squirrel, Red-bellied Squirrel, Hoary bellied Squirrel and Himalayan Striped Squirrel. A set of established trails were used to survey the sites. The diversity of squirrels in the fragments was explained by size of the fragments, intactness of the forest and disturbance levels. The fragments were in a state of continuous degradation, habitat variables being influenced more by disturbance levels than by size. Medium-sized fragments continue to retain the diversity of squirrels by the virtue of small pockets of intact habitat in the fragments, while small fragments have been rendered depauperate by synergistic effects of habitat loss, degradation and hunting. Density estimation using trails as transects under distance sampling framework revealed that densities of Malayan Giant Squirrel showed a declining trend in medium fragments and the absence of the species in the small fragments. Densities of Himalayan Striped Squirrel were comparable in large forests and medium fragments and the species was not recorded from the small fragments. Densities of RBS were high across all sites, including the small fragments Time activity budget, vertical space use for foraging and diet were investigated underthe umbrella of changes along basic niche dimensions of time, space and diet. Niche width along time decreased in the fragments for all squirrels suggesting reduced active periods. For the Malayan Giant Squirrel, niche width decreased along the other two dimensions as well in the fragments, suggesting restriction of foraging strata and diet. On the other hand, for the Red-bellied Squirrel, niche width increased along vertical space use and diet axes suggesting expansion of niche in the fragments. These differential responses of species to habitat fragmentation resulted in changes in overlap between species in fragments and a potential alteration of competitive dynamics between species in modified habitat conditions. Comparing trends in density estimates and responses of squirrels along basic niche dimensions revealed that similar inferences can be drawn from the two assessments about the potential sensitivity of a species to habitat fragmentation. Responses along basic niche dimensions can be possibly used to make prior assessments of responses to habitat alteration before differences in densities, which is a more gradual process, start to show up. It is clear from the findings of the study that diversity of squirrels depends on quality of habitat. Medium-sized fragments have the potential to retain the diversity of squirrels. They should be prioritized and accorded enough protection to deter further degradation and hunting in these fragments. Malayan Giant Squirrel and Himalayan Striped Squirrel appear to be sensitive to habitat fragmentation, while the Red-bellied Squirrel appears to be tolerant.Item Effect of Inter-Habitat Matrix on Tropical Evergreen Forest Remnants : An Emprical Test of Matris-Tolerrance Hypothesis on Butterflies(Wildlife Institute of India, Dehradun, 2013) Kumar, Deepak C.; Talukdar, Gautam; Habib, Bilal; Kunte, KrushnameghRecent studies on habitat fragmentation has highlighted the importance of inter-habitat matrix and the need for a shift from traditional binary perspective to a 'matrix composition' ·perspective for understanding species diversity patterns in human modified landscapes . Matrix-tolerance model provides a simple framework for understanding the sensitivity of species to fragmentation by simultaneous study of native forest patches and surrounding matrix. According to this model, abundance of a species in the matrix is inversely proportional to its vulnerability to fragmentation. This study tested the matrix-tolerance hypothesis on butterflies of tropical evergreen forest remnants, surrounded by a matrix of coffee plantation and paddy field in Kodagu region of Western Ghats. Western Ghats is rich in butterfly fauna represented by 333 species of which 33 are endemic to the biogeographic region. The region is also characteristic in having human modified habitats with relatively large proportion of native forest patches which calls for a landscape level approach for conservation. In order to test the matrix tolerance hypothesis sampling was carried out in 16 sites which included 7 in fragments (sacred groves), 7 in matrix (5 in coffee plantations, 2 in paddy field) and 2 in large contiguous forest (Reserve Forest). For abundance estimation of butterflies, time constrained surveys were carried out 3 times in each site between January 10 and April 8, 2013. An index related to fragmentation vulnerability was generated for each species using abundance data obtained from time-constrained surveys. The Fragmentation Vulnerability Index, FVI was defined as the ratio between average abundance of the species in the fragments and average abundance in the continuous patch. Spearma'n's rank correlation was then used to test the association between rank FVI and rank matrix abundance. Various microclimatic and habitat variables were measured in matrix sites and Generalized Linear Models (GLMs) were constructed to test their association with estimated species richness. Analyses were carried out using SPSS 16 and R (version 3.0.1, R core team 2013) software. The present study shows that the relation between abundance of species in the inter-habitat matrix and its vulnerability to fragmentation is positive and significant (rs= 0.514, p = 0.001, N = 37). Species which are capable of tolerating the matrix are found to be less vulnerable to fragmentation. Some species deviate from the expected model in their response to habitat fragmentation which could possibly be explained by examining species specific traits. Fragment size didn't have a significant effect on relation between matrix abundance and fragmentation vulnerability index (F=0.758, p=0.387, df=l), unlike expected from previous studies. This could either be due to smaller range of fragment sizes in the present study or due to confounding factors like patch isolation and patch quality which can mask the effect of patch size. Among various habitat 'and microclimatic variables, canopy cover was found to be 'important predictor of ciliated species richness in matrix sites (weight = 0.8, ~ = 0.8, P = 0.008). Coffee plantations generally have a moderate level of canopy cover which is favorable for most butterfly species. But compared to paddy field~ the canopy cover is higher in coffee plantations and this could be the reason for increase in species richness with increasing canopy cover in matrix sites.Item Floristic Composition and Patterns of Regeneration of Rainforest Trees in the Fragmented Forests of the Anamalai Hills, Southern Western Ghats(Wildlife Institute of India, Dehradun, 2003) Balasubramaniam, Priya; Qureshi, Qamar; Chellam, RaviThe word diverse is almost a synonym for tropical rainforests. In no other habitat are found such an enormous number of life forms. These highly diverse systems are now facing severe threats as a result of habitat fragmentation. The aim of this study was to study the floristic composition and patterns of regeneration in the fragmented forests of the Anamalai hills, southern Western Ghats.Six fragments were chosen which varied in size and disturbance levels. They were- Iyerpadi (>2600ha), Andiparai (>185ha), Puduthotam (92ha), Pannimedu (66ha), Varattuparai 1c (11ha) and Varattuparai 4 (4ha). Quadrats of · 3 sizes were used to sample for different variables. 20 x 20m quadrats were used to enumerate tree sp, 5 x 5m quadrats were used to enumerate sapling sp and 1 x 1 m quadrats were used to count the numbers of seedlings. Height (m), GBH (cm), lopping I cutting signs, altitude, canopy cover, presence of weedy shrubs and ground cover of weedy herbs were the other variables measured. A total of 112 quadrats were laid, 25 in the first 4 fragments, 9 and 3 in the last two respectively. The findings revealed that tree and sapling generic richness showed a negative relationship with disturbance and time since isolation. Their correlations with area though positive were weak. Fragments were subjected to varied nature and levels of disturbance. Fragment characteristics such as area, time since isolation did influence the patterns of tree and sapling composition though weakly. There is an extremely weak correspondence between the tree and sapling composition of each fragment. There was a high number ' of non rainforest species in fragments which were relatively more disturbed. Relatively undisturbed fragments were more rich in rainforest trees · and saplings. Fragments showing higher levels of canopy openness were relatively more disturbed than others. Disturbed fragments also showed higher levels of weed invasion. Iyerpadi showed the highest generic richness in trees and saplings. Varattuparai 4 showed the least richness in both trees and sapling. Human disturbance due to its chronic. nature was the principal predictor of both tree and sapling composition.