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Author: Gopika, Rani K S × Author: KAU × End date: 2015 × Start date: 2015 ×
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    ThesisItemOpen Access
    Modeling soil carbon dynamics of two major ecosystems of humid tropics
    (Academy of Climate Change Education and Research, Vellanikkara, 2015) Gopika, Rani K S; KAU; Betty, Bastin
    A study on “Modelling soil carbon dynamics of two major ecosystems of humid tropics” was carried out in the Academy of Climate Change Education and Research (ACCER) during 2014-2015. The study was done using two soil carbon models such as Roth-C and CENTURY. The objectives of the study included the evaluation of suitability of these two models in rice and teak ecosystems and also to analyse the soil organic carbon changes due to predicted climate change scenarios. The study was based on secondary data sets collected from experiments done in paddy fields and teak plantations of Pattambi and Thrissur areas respectively belonging to humid areas. The simulated total soil organic carbon (1965 to 2050) by Roth-C and CENTURY models was found to be declining in rice ecosystem. The active carbon in rice ecosystem showed decreasing trend and thereafter it was showing an increasing trend. In case of slow carbon it showed a gradual declining trend during the period from 1965 to 1990. There after it started to increase in a rapid manner during the next eleven years and afterwards it started decreasing. The passive carbon in rice ecosystem kept on increasing throughout the simulation period. In teak ecosystem, both the models Roth-C and CENTURY predicted a declining trend of total soil organic carbon. The active carbon of teak ecosystem decreased by the end of third year and slowly increased by ninth year. By the end of fifty five year it showed a rapid decline and slowly increased by the following years. Slow carbon pool showed a declining trend up to thirty years and kept on increasing to the next thirty years. Then it showed a rapid decline and thereafter it started to increase. The passive carbon kept on decreasing throughout the period. The model efficiency of Roth-C and CENTURY models for rice ecosystem were 0.63 and 0.82, respectively whereas for teak ecosystem the values were 0.69 and 0.88. Hence it was concluded that for simulation of soil organic carbon, both the models are suitable, but CENTURY model was more efficient than Roth- C model. From the study based on different RCP scenarios, RCP 8.5 had predicted higher temperature and precipitation values compared to others (RCP 6.0, RCP 4.5 and RCP 2.6) over both Pattambi and Vellanikkara. In rice ecosystem, it was noticed that in 2015 and 2050, RCP 2.6 recorded the highest values of total soil organic carbon and the lowest values were by RCP 8.5, respectively. In the case active carbon, RCP 4.5 recorded the highest values and RCP 8.5 recorded the lowest values. The highest value of slow carbon was recorded by RCP 2.6 and the lowest by RCP 8.5. The predicted values of passive carbon showed highest values by RCP 6.0 and recorded the lowest by RCP 4.5. In the study based on predicted climate change scenarios in teak ecosystem, RCP 4.5 recorded highest values of total soil organic carbon in 2015 and 2050 where as the lowest value was found by RCP 6.0 in 2015 and RCP 8.5 in 2050. The highest value of active carbon was found in 2015 by RCP 4.5 and in 2050 by RCP 2.6. The lowest values of active carbon were recorded by RCP 6.0 and RCP 8.5 in 2015 and 2050 respectively. In 2015 the highest value of slow carbon was recorded by RCP 4.5 and in 2050 by RCP 2.6. The least value of slow carbon was recorded in 2015 by RCP 6.0 and in 2050 by RCP 8.5. The passive carbon simulated by different RCPs, it was observed that RCP 4.5 predicted the highest value in 2015 and 2050. Then the lowest values recorded by RCP 6.0, respectively The present study indicated that modelling is suitable for studying carbon dynamics in soils under rice and teak ecosystems. It highlights the potential of CENTURY model over Roth-C model in terms of simulation of soil carbon. Using different scenarios it is possible to know that, what might be the future conditions of soil carbon and its different pools.
  • Thumbnail Image
    ThesisItemOpen Access
    Modelling soil carbon dynamics of two major ecosystems of humid tropics
    (Academy of Climate Change Education and Research, Vellanikkara, 2015) Gopika, Rani K S; KAU; Betty, Bastin
    A study on “Modelling soil carbon dynamics of two major ecosystems of humid tropics” was carried out in the Academy of Climate Change Education and Research (ACCER) during 2014-2015. The study was done using two soil carbon models such as Roth-C and CENTURY. The objectives of the study included the evaluation of suitability of these two models in rice and teak ecosystems and also to analyse the soil organic carbon changes due to predicted climate change scenarios. The study was based on secondary data sets collected from experiments done in paddy fields and teak plantations of Pattambi and Thrissur areas respectively belonging to humid areas. The simulated total soil organic carbon (1965 to 2050) by Roth-C and CENTURY models was found to be declining in rice ecosystem. The active carbon in rice ecosystem showed decreasing trend and thereafter it was showing an increasing trend. In case of slow carbon it showed a gradual declining trend during the period from 1965 to 1990. There after it started to increase in a rapid manner during the next eleven years and afterwards it started decreasing. The passive carbon in rice ecosystem kept on increasing throughout the simulation period. In teak ecosystem, both the models Roth-C and CENTURY predicted a declining trend of total soil organic carbon. The active carbon of teak ecosystem decreased by the end of third year and slowly increased by ninth year. By the end of fifty five year it showed a rapid decline and slowly increased by the following years. Slow carbon pool showed a declining trend up to thirty years and kept on increasing to the next thirty years. Then it showed a rapid decline and thereafter it started to increase. The passive carbon kept on decreasing throughout the period. The model efficiency of Roth-C and CENTURY models for rice ecosystem were 0.63 and 0.82, respectively whereas for teak ecosystem the values were 0.69 and 0.88. Hence it was concluded that for simulation of soil organic carbon, both the models are suitable, but CENTURY model was more efficient than Roth- C model. From the study based on different RCP scenarios, RCP 8.5 had predicted higher temperature and precipitation values compared to others (RCP 6.0, RCP 4.5 and RCP 2.6) over both Pattambi and Vellanikkara. In rice ecosystem, it was noticed that in 2015 and 2050, RCP 2.6 recorded the highest values of total soil organic carbon and the lowest values were by RCP 8.5, respectively. In the case active carbon, RCP 4.5 recorded the highest values and RCP 8.5 recorded the lowest values. The highest value of slow carbon was recorded by RCP 2.6 and the lowest by RCP 8.5. The predicted values of passive carbon showed highest values by RCP 6.0 and recorded the lowest by RCP 4.5. In the study based on predicted climate change scenarios in teak ecosystem, RCP 4.5 recorded highest values of total soil organic carbon in 2015 and 2050 where as the lowest value was found by RCP 6.0 in 2015 and RCP 8.5 in 2050. The highest value of active carbon was found in 2015 by RCP 4.5 and in 2050 by RCP 2.6. The lowest values of active carbon were recorded by RCP 6.0 and RCP 8.5 in 2015 and 2050 respectively. In 2015 the highest value of slow carbon was recorded by RCP 4.5 and in 2050 by RCP 2.6. The least value of slow carbon was recorded in 2015 by RCP 6.0 and in 2050 by RCP 8.5. The passive carbon simulated by different RCPs, it was observed that RCP 4.5 predicted the highest value in 2015 and 2050. Then the lowest values recorded by RCP 6.0, respectively The present study indicated that modelling is suitable for studying carbon dynamics in soils under rice and teak ecosystems. It highlights the potential of CENTURY model over Roth-C model in terms of simulation of soil carbon. Using different scenarios it is possible to know that, what might be the future conditions of soil carbon and its different pools.