PG Thesis
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Item Soil carbon efflux and litter decomposition in natural forests of KFRI Peechi campus(Academy of Climate Change Education and Research Vellanikkara, 2017) Nirajlal, K; Sreejith, K ALitter dynamics and soil respiration are of great interest in climate change studies due to their roles in recycling carbon and nutrients. Present study was conducted with the objectives of understanding patterns and the process of litter dynamics and the role of weather on soil carbon efflux. Litterbag technique was used to determine the decomposition of litter for 180 days. Soil CO2 fluxes were measured for a period of three weeks in a month for up to 180 days. Mass loss, total carbon of decayed litter and litter fall were quantified. Major tree species’ litter dynamics were also determined. Relationship between soil CO2 efflux with soil and weather parameters were determined using correlation technique. Decomposition constant with a value of 0.009 day-1 was found in moist deciduous forest. Among weather parameters, soil carbon dioxide efflux had weak positive correlation with rainfall and relative humidity and had weak negative correlation with temperature. Among soil parameters, soil carbon dioxide efflux had very weak positive correlation with soil organic carbon and soil moisture. The weak correlation coefficient value came due to lesser variables which indicates duration of this study is not enough. Among species wise study, Terminalia paniculata possess higher deciduous properties that directly contributing more to soil carbon sequestration and it was also found that Tectona grandis had high carbon content per unit volume compared to other species. But the species Macaranga peltata might sequestered more amount of carbon in a short time due to its high decomposition rate. The study highlights the different responses of soil CO2 efflux to weather and soil parameters but suggests a long duration study for in-depth analysis which is very relevant in carbon dynamics and climate change studies.Item Nutrient management for coconut based multi-storeyed cropping system in a typical coastal sandy zone(Department of agronomy, College of agriculture, Padannakkad, 2015) Farsanashamin, P; Anilkumar, A SItem Ecophysiological studies in disturbed forest ecosystem: a case study at Pattikkad(College of Forestry, Vellanikkara, 1993) Nameer, P O; Asokan, P KMoist deciduous forests of Kerala are prone to comparatively more biotic interference, as it occupies a buffer zone between human population and evergreen forests. An investigation was carried out at Pattikkad range of Peechi- Vazhani wildlife Sanctuary, in Trichur Forest Division, Kerala. The objectives of the present study were to understand the floristic, structural, functional, physiological, edaphic and micrometeorological changes accompanying degradation. Three experimental plots namely highly disturbed ( PATK – BT), partially disturbed (PATK – MD) and more less undisturbed (PATK – TP) were identified taking into consideration the proximity to human settlement. Each plot had a size of 10000 m2 and were subdivided into quadrats having 100 m2 each and observations on frequency, density, basal area, Importance Value Index (IVI), diversity indices, height – diameter relationships, regeneration pattern, litter quantification, litter decomposition, phenology, leaf area, leaf area index, light infiltration, physic-chemical properties of soil, soil moisture and soil temperature were recorded at periodic intervals for an year. The results indicate that the moist deciduous forest tend to become a semi – evergreen forest it left undisturbed for several years. The undisturbed (PATK – TP) plot recorded maximum density (882), in 143 species (48 families) whereas the density is only 154 in the highly disturbed (PATK – BT) plot. The number of species at PATK – BT is only 31 (19 families). The species diversity is also very high in the undisturbed plot (Simpson’s index = 0.97 ; Shanon –Weiner’s index = 5.97) whereas the Simpson’s index and Shannon – Weiner’s index are 0.92 and 4.16 respectively for PATK – BT. The height – diameter relationship clearly show that the set of the future is more or less absent in the disturbed plots. The regeneration survey reveals that the regenerating community is sparse in the disturbed plots. While the disturbed plots (PATK – BT and PATK – MD) had 3825 and 5045 seedlings per hectare the undisturbed (PATK – TP) plot had 26,500 seedlings per hectare. The litter production was found to be positively correlated with basal area. The rate of litterfall ranged from 6.14 t ha-1 to 8.66 t ha-1 in the moist deciduous forests. The decay rate was fastest in the disturbed (PATK – BT) plot (‘K’ value = 0.26) and slowest in the undisturbed (PATK – TP) plot (‘K’ value = 0.17). The light infiltration to the forest floor was maximum in the highly disturbed (PATK – TP) plot (44.42 mol m-2 s-1 ). The PATK – TP had a leaf area index of 4.04 and that of PATK BT was only 1.06 While most of the leaves in the undisturbed plot belonged to notophyllous (leaf size = 20.25 cm2 to 45.00 cm2 ) type of leaves, that of distributed plots were mesophyllous (leaf size = 45.00 cm2 to 182.25 cm2 ). The physic – chemical properties of the soil were better in the undisturbed plot when compared to the disturbed plots. The gravel content was 23 to 33 per cent at PATK – BT whereas it was 22 to 23 per cent at PATK – TP. Soil was more acidic (pH 5.51 to 5.57 ) at PATK – TP, whereas at PATK – BT the pH varied from 6.13 to 6.14. The organic carbon at undisturbed (PATK – TP) plot ranged between 1.4 to 3 per cent while in the highly disturbed (PATK – BT) plot ranged from 0.9 to 2 per cent. N, P and K also followed a similar pattern. The soil moisture was always maximum in the undisturbed (PATK –TP) plot. The soil moisture varied between 14 per cent (March) to 50 percent (July). The soil moisture at the highly disturbed (PATK – BT) plot was always the minimum. The values varied between 3 per cent (March) to 30 per cent (July). The undisturbed (PATK – TP) plot consistently recorded minimum soil temperature throughout the year when compared to the disturbed plots. The values varied between 220 C (July) to 280 C (April). Whereas in the highly disturbed (PATK – BT) plot the soil temperature was always high. The soil temperature recorded at PATK – BT ranged between 250 C (July) to 360 C (April).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.