PG Thesis
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Item Leaf litter dynamics of ornamental flowering trees(Department of Forest Management and Utilisation, College of Forestry, Vellanikkara, 2007) Jinsy M Joseph; Gopikumar, KA detailed study was conducted at the College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur, Kerala during 2005-2007, to compare the rate of decomposition and mineralization pattern of leaf biomass of five ornamental flowering trees viz., Bauhinia purpurea Lamk., Cassia fistula Linn., Gliricidia sepium Kunth., Lagerstroemia speciosa Auct. and Peltophorum pterocarpum Baker. The experiment was laid out in a typical homegarden. The rate of leaf biomass decomposition was generally faster for all the species studied. Of the five species studied, G. sepium and L. speciosa showed faster rates of leaf biomass decomposition while B. purpurea recorded the lowest rate. Generally, all the species followed a biphasic pattern of biomass decomposition. The initial nitrogen, C: N ratio, lignin content and lignin: nitrogen ratio of the leaf biomass influenced the decomposition rate. The fibre content of leaf biomass was also found to have significant affect on the rate of decomposition. Leaf biomass of L. speciosa and G. sepium showed rapid release of all the nutrients compared to that of B. purpurea. Among the nutrients, potassium registered a faster rate of mineralization, followed by nitrogen for all the species except L. speciosa, which showed faster mineralization for nitrogen. Lower mineralization tendency was seen for phosphorus in all the species. The influence of leaf litter decomposition on soil pH and electrical conductivity was not significant. However, content of most of the nutrient elements in the soil was significantly improved with respect to all the species particularly towards the end of the study.Item Evaluation of tree species for growth, wood properties and leaf nutrient content(Department of Forest Management and Utilisation, College of Forestry, Vellanikkara, 2008) Harsha T Hegde; Gopikumar, KThe present study was conducted in the College of Forestry, Kera1a Agricultural University, Vellanikkara to evaluate the growth performance, biomass production, wood properties and leaf nutrient content of the selected tree species grown in the arboretum during the period 2006 to 2008. The species selected for the study includes Adenanthera pavonina, Artocarpus heterophyllus, Bridelia retusa, Ceiba pentandra, Hydnocarpus wightiana, Hymenodictyon excelsum, Peltophorum pterocarpum, Pterocarpus santalinus, Samadera indica and Tectona grandis. Data related to growth measurements from 1992 to 2006 have been collected from the college department. The results revealed that the species like Tectona grandis, Ceiba pentandra and Artocarpus heterophyllus were fast growing in terms of height and girth while Samadera indica as slow growing. Peltophorum pterocarpum produced highest number of branches. The spread was the maximum for Artocarpus heterophyllus followed by Adenanthera pavonina. During the end of the study in 2008, maximum volume increment was recorded by Ceiba pentandra while the lowest was for Samadera indica. The total biomass production was found to be the maximum for Ceiba pentandra in terms of fresh and Adenanthera pavonina in terms of dry weight while the lowest total biomass was produced by Pterocarpus santalinus in terms of both fresh and dry weights. Trunk accounted for maximum biomass production followed by branches. The contribution of trunk was followed by branches in all the tree species except Ceiba pentandra where the dry weight of leaves was more than that of branches. Adenanthera pavonina, Tectona grandis and Pterocarpus santalinus produced more heartwood percentage compared to other species. Sapwood percentage recorded was the maximum for Samadera indica. Pterocarpus santalinus, Hydnocarpus wightiana and Ceiba pentandra were having high calorific values and hence could be used for fuel wood purpose also. Specific gravity was found to be the maximum for Samadera indica and minimum for Pterocarpus santalinus. Leaf tissue nitrogen content was significantly highest in Adenanthera pavonina followed by Pterocarpus santalinus. The phosphorus content was found to be the maximum in Artocarpus heterophyllus while minimum in Ceiba pentandra. Leaves of Tectona grandis recorded the maximum content of potassium while the lowest was for Artocarpus heterophyllus. The present series of investigations indicate the scope of selecting fast growing tree species with high biomass production, better wood qualities and high foliage nutrient content for distribution to farmers for social/agroforestry and even for general afforestation programmes.Item Nutrient content and decomposition of leaf litter of Acacia mangium Willd as affected by season and field conditions(Department of Silviculture and Agroforestry, College of Forestry, Vellanikkara, 1995) Ramakrishna Hegde; Gopikumar, KA detailed experiment was conducted at the College of Forestry, Kerala Agricultural University, Vellanikkara, Thrissur, during the period from 1993 to 1995 to study the nutrient content and pattern of leaf litter decomposition of Acacia mangium Wild. During south west monsoon and north east monsoon seasons. The experiment was conducted both in home garden and open area. The rate of decomposition was faster in all the study situations. The initial nitrogen, lignin, C:N ratio and lignin : nitrogen ratio of leaf litter were found to exert profound influence on the rate of decomposition. The decomposition rate was found to be a function of time, soil moisture and soil temperature. The nutrient release pattern in almost all cases followed a characteristic biphasic model with an initial rapid phase followed by a slower latter phase. Among the different nutrients, potassium showed a faster rate of mineralisation in most of the situations while calcium and nitrogen mineralised slowly. Among the several mathematical models tried to predict the absolute amount of nutrients in the residual mass, the second order hyperbolic function was found to be good fit in most of the cases. Though the PH was not altered significantly by the decomposing litter mass, the content of most of the nutrient elements is found to be drastically influenced.