PG Thesis
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Item Monitoring and evaluation of forest canopy density model in Nilambur forests, Kerala using geospatial techniques(Department of Forest Resource Management, College of Forestry,Vellanikkara, 2025) Ajay Antony.; Srinivasan, KThe study entitled ‘Integrated management of Fusarium wilt of yard long bean in homesteads’ was undertaken at College of Agriculture, Vellayani and Integrated Farming System Research Station (IFSRS), Karamana during 2023-25 with an objective to develop an integrated management package for the vascular wilt of yard long bean incited by Fusarium oxysporum using bioagents and biofumigants in homesteads. The culture of F. oxysporum (accession no: MZ706472.1) maintained at IFSRS, Karamana was used for the study. The mycelia of the pathogen appeared as white and fluffy with a characteristic pale pink to purplish pigmentation. Microconidia were ovoid or elliptical with 0 - 1 septa, while macroconidia were fusiform with 3 – 4 septa. Chlamydospores were globose with a diameter of 6 -10 μm. The pathogen was mass multiplied in sorghum-sand medium (SSM) (2:1:1 ratio) and complete colonization of the fungus was recorded at 5 days after inoculation (DAI). Koch’s postulates were proved in 15-days-old yard long bean seedlings (var. Githika). The disease symptoms initiated as yellowing of older leaves at 7 days after transplanting, which further progressed as defoliation, withering, wilting and seedling death. In vitro studies on the evaluation of antifungal potential of bioagents, botanicals and biofumigants revealed that garlic bulbs (2 g plate-1) completely (100%) inhibited the pathogen. Rhizobium sp. (KAU) inhibited the mycelial growth by 67.77 per cent and tested positive for siderophore production, indicated by a colour change of Chrome Azurol S (CAS) agar from blue to orange. In vivo seed treatment studies revealed that sowing of seeds in soil applied with AMF @ 5 g seed-1 followed by transplanting was the promising treatment (no incidence of disease) for the management of Fusarium wilt, along with enhanced seed germination (100%), leaf number (11.00), leaf area (24.17 cm2), shoot length (16.17 cm), root length (19.83 cm) and root-shoot ratio (5.33) of the seedling. Seed treatment with Rhizobium sp. followed by transplanting was the next promising treatment with the highest leaf area (27 cm2). Scanning electron microscopy revealed intact cell structure and absence of clogging 128 in vascular tissues of the above plants where as the pathogen inoculated control recorded its hypha emerging out of xylem vessels, which were damaged and extensively clogged. A pot culture study was undertaken in yard long bean var. Githika to develop an integrated package for management of vascular wilt disease. The treatment viz., soil testbased lime application at 2 weeks before planting + soil application of Trichoderma sp. enriched in cow dung – neem cake mixture (9:1) @ 1 kg pot-1 at one week before sowing (WBS) + soil application of AMF @ 5 g seed⁻¹ at sowing followed by transplanting + soil application of PGPR mix II @ 20 g L-1 at 20, 40 and 60 DAS (T6), recorded the least disease incidence (55.50%) and disease severity (19.44%), with the highest yield (945 g plant-1with 54 pods), among the treatments. The highest AMF root colonization (49%) and number of nodules (47.00) were also recorded in this treatment. Significant reduction in the population of the pathogen in soil/ pot was also recorded in this treatment at 30 and 60 DAS. The next promising treatment was same as the best one, with soil application of PGPR mix II @ 20 g L-1 replaced by Trichoderma sp. enriched in cow dung – neem cake mixture (9:1) @ 1 kg pot-1 at 20, 40, and 60 DAS (T3) which recorded reduced disease incidence (66.66%) and severity (31.76%) with higher yield (908.33 g plant-1from 50.00 pods), AMF root colonization (45.00%) and nodules (40.67). Peak activity of peroxidase (12.07 μg g-1 min-1), polyphenol oxidase (1.587 μg g-1 min-1), and phenylalanine ammonia lyase (11.703 μg g-1 min-1) at 72 hours after inoculation was recorded in the promising treatment. Thus, the present study revealed the integrated disease management package viz., soil test-based lime application at 2 weeks before planting + soil application of Trichoderma sp. enriched in cow dung – neem cake mixture (9:1) @ 1 kg pot-1 at one WBS + soil application of AMF @ 5 g seed⁻¹ at sowing followed by transplanting + soil application of PGPR mix II @ 20 g L-1 at 20, 40 and 60 DAS can effectively manage vascular wilt of yard long bean incited by F. oxysporum in homesteads. Furthermore, the study confirms a beneficial quadripartite association among AMF, Trichoderma sp. and the plant growth promoting rhizobacteria in yard long bean plants, as observed from the effective management of the disease and enhanced plant growth and yield attributes even in the presence of the soil borne pathogen.Item Risk assessment and habitat invasibility of Ageratine adenophora (Spreng) R.M. King & H.Rob in Pampadum Shola National park, Kerala(Department of Forest Resource Management, College of Forestry, Vellanikkara, 2024-12-17) Nikhil, P V; Aneesh, K SItem Comparative assessment of the spatial distribution and edaphic attributes of mangroves in Perumba and Puthuvype regions(Department of Forest Resource Management, College of Forestry, Vellanikkara, 2024-01-25) Rohan, M S.Mangroves are characterized by salt-tolerant vegetation thriving in tropical and subtropical coastlines. It provides critical ecological services and a source of livelihood for coastal communities. Globally, these crucial ecosystems are currently under threat due to the over-exploitation of natural resources. The mangroves in the state of Kerala have witnessed a drastic reduction in the area from seven hundred sq. km to a mere nine sq. km over the last five decades. Developmental activities and anthropogenic disturbances in the coastal areas are the major threats to these sensitive ecosystems. The knowledge of the extent of disturbance, the changes brought by the anthropogenic activities and their effect on the mangrove vegetation are the prerequisites for the sustainable management of these ecosystems. In this context, the present research work studied the extent of change in mangrove areas, variation in vegetation structures, soil and water properties among two contrasting regions namely, the Perumba river region with low and the Puthuvype region with high human disturbances. The Land Use Land Cover (LULC) classification for the current year has shown almost same percentage of mangroves to the total area in both the studied regions. In the present study, we used the three most widely used machine learning algorithms for the classification process. Among the machine learning algorithms studied, the Gradient Tree Boost (GTB) algorithm with a combination of Sentinel 1, 2 datasets and few spectral indices shown exemplary performance (88 % accuracy) in classifying mangrove areas. Change detection analysis showed a positive trend in mangrove cover in Perumba region (7.03 % increase) and contrarily a negative trend (66.51 % decrease) in the Puthuvype region during the study period (2013 - 2023). Phytosociological analysis figured out seven species belonging to four families in both Perumba and Puthuvype regions. The only difference in the species composition between the two regions is that Kandelia candel was found only in Perumba region, while it was replaced by Bruguiera gymnorhiza in the Puthuvype region. The common species present among these two regions were Avicennia officinalis, Bruguiera cylindrical, Excocaria agallocha, Rhizophora apiculate and Rhizophora mucronata. The Perumba region exhibits higher vegetation diversity indices when compared to the Puthuvype region. Perumba region exhibited higher seedling, tree, and sapling density, indicating a healthier mangrove ecosystem. In both regions, the majority of trees belong to the girth xii class of 20-30 cm. Further, Important Value Index (IVI) identified Avicennia officinalis as a dominant species followed by Rhizhophora mucronata in both the regions. Soil analysis showed a significant variation for chemical properties between the regions studied. Electrical conductivity, soil organic carbon, available nitrogen, available potassium, sodium, magnesium, lead, and chromium levels were recorded higher values in the Perumba region. Meanwhile, available phosphorus content was found higher in the Puthuvype region. In addition, biological properties viz, actinomycetes, bacteria, and fungi populations were higher in the Perumba region. Moreover, water analyses also revealed a maximum electrical conductivity, salinity and turbidity in the Perumba region. Altogether, the study showed a declining mangrove population in the Puthuvype region due to significant changes in the mangrove ecosystem brought by the intense anthropogenic interventions in the mangrove ecosystem, necessitating immediate action for the restoration of this fragile ecosystem.Item Ecotourism carrying capacity of Nelliampathy, Palakkad, Kerala(Department of Forest Resource Management, College of Forestry, Vellanikkara, 2024-02-26) Rathna, V.; Gopakumar, SEcotourism is globally embraced as a niche segment of sustainable tourism, transforming conventional mass tourism and increasingly being recognized as a strategy for sustainable forest management in natural areas. However, to address the potential threats arising from an excessive influx of visitors and inadequate regulations in these areas, it is imperative that effective ecotourism planning and management must establish and uphold optimal thresholds, commonly denoted as the “carrying capacity of destinations”. Despite its importance in managing visitor numbers, many key ecotourism destinations currently do not adhere to this concept. This study focused on assessing the ecotourism carrying capacity (ETCC) for one of the major hill-based ecotourism attractions in Kerala, ‘Nelliampathy’, which faces immense pressure from tourists, by taking into account various site-specific physical, biological or ecological and social factors. Tourist's perceptions were also obtained through a survey conducted with 91 respondents with a pre-tested questionnaire, scheduled every fortnight from June to September. Furthermore, a brief study on the valuation of the use (recreational) and non-use values of Nelliampathy was carried out. The study established Effective Carrying Capacity (ECC) estimates for various destinations: Government Orange Farm, Kesavanpara, Seetharkundu, Pakuthippalam KFDC, Minnampara and Karappara Bridge at 587, 302, 153, 110, 40 (approximately 5 trips per day) and 8 visitors per day, respectively. The occupancy rate of destinations revealed that Karappara far exceeded the carrying capacity, followed by Minnampara and Seetharkundu. While the current visitation rates are actually below these estimates for some destinations like Kesavanpara and Govt. Orange Farm, there is a risk of congestion and overcrowding, particularly during peak seasons and holidays. ETCC assessment underscores the importance of improving the management capacity in terms of personnel, infrastructure and equipment and judicious monitoring of limiting factors that could reasonably increase the carrying capacity of these sites. Extended projection periods, especially for KFDC and Govt. Orange Farm could be strategically utilized to alleviate tourist pressure. The tourist profile indicated a significant majority from Kerala (92.31%), mainly comprising students (25.27%) and middle-aged individuals (46.15%) with a literate background (41.76%), favouring exclusive weekend day trips to Nelliampathy (79%). Overall, tourists held a positive perception about natural attractions and environmental characteristics of Nelliampathy, though a neutral stance was observed regarding travel-related concerns and other tourist assistance services. Despite its aesthetic beauty, Nelliampathy received negative feedback due to limited accessibility to emergency services. Tourists typically used personal cars (47%) and often engaged in group tourism with friends and family. Substitute destinations suggested include Munnar, Wayanad, Parambikulam Reserve and Silent Valley Park. The anticipated increase in tourist flows in Nelliampathy necessitates a re-evaluation of destination ticketing systems. Visitor willingness to pay (WTP) reflected environmental awareness, providing an opportunity for engaging tourists in destination improvement initiatives. This comprehensive understanding aids in shaping the future ecotourism management plan for Nelliampathy and the study offers a potential model for assessing carrying capacity at other ecotourism sites in the state