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 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.Item Litter dynamics of selected multipurpose tree species used as pepper standards(Department of Silviculture and Agroforestry, College of Forestry, Vellanikkara, 2005) Bino George; Kunhamu, T KA field trial was conducted at Livestock Research Station, Thiruvazhamkunnu, Kerala during August 2002 - August 2003 to characterize the litter dynamics and nutrient flux associated with seven MPTS used as support for black pepper. The study covered quantification of litter production, litter decomposition, nutrient release pattern through litter route and the changes in soil properties and site productivity in terms of pepper yield. The pepper support tree species under study included, Casuarina equisetifolia J.R. & G. Forst, Macaranga peltata (Roxb) M.-A, Ailanthus triphysa (Dennst.) Alston, Artocarpus heterophyllus (Linn), Acacia auriculiformis (A. Cunn.) ex Benth, Grevillea robusta (A. Cunn.) ex R. Br. The experiment was superimposed on a pre-existing, fourteen- year- old pepper stand in a Randomized Block Design with three replications. Generally, moderate levels of litter production has been shown by different pepper support trees under investigation. Annual litter yield was maximum for Artocarpus (4653.63 kg ha-1) and Macaranga (4550.88 kg ha-1), while Ailanthus (2221.25 kg ha-1) yielded minimum. Nutrient level in litterfall varied between species. Maximum N content was associated with nitrogen fixing trees such as Acacia and Casuarina. The leaf litter decomposition rate was generally faster for all the species with almost 90 per cent mass loss within three months. Artocarpus showed faster rate of litter decomposition while Macaranga and Ailanthus were relatively slow decomposers. Unprecedented heavy mass loss was registered by Casuarina, Grevillea and Acacia from their litterbags owing to physical nature of the litter. All the selected tree species showed a characteristic biphasic pattern of litter decomposition. Decay coefficients ranged from 0.73 (Casuarina) to 0.19 (Macaranga). The exponential equations relating mass loss over time were worked out for all the species. The lignin content of the leaf litter was found to excerpt negative influence on the rate of litter decomposition. The general order of nutrient in terms of their releasing capacity from the decomposing litter was K>P>N. Acacia and Artocarpus registered faster rate of nutrient accretion. Changes in soil properties such as moisture content, pH and bulk density was marginal on account of the presence of tree species. Leguminous species like Acacia was found to improve the soil N content. Maximum rainfall interception was attributed to Artocarpus followed by Macaranga. The yield of pepper in terms of dry berry weight was maximum for Acacia (2.56 t ha-1) and Artocarpus (1.91 t ha-1). Better physical suitability, high lopped out turn and nutrient turnover potential suggest these species as ideal candidates for trailing pepper. However, the general reduction in soil physical and chemical properties and reduction in the yield of black pepper for each standard over years suggest a declining trend in the productivity of this system, probably induced by the ageing of the stand as well as the heavy management practice followed.