Litter decomposition as a function of temperature and land use

Nkhoma, Lusungu
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Soils have to be managed so that carbon stocks are sustained in order to conserve this valuable resource. This study examined litter decomposition in different land use types and different temperatures in South Africa in order to contribute to the development of a global map of litter decomposition rates. The research project used the Teabag Index developed by Keuscamp et al (2013), which used green and Rooibos teabags to assess litter decomposition rate constants through the weight loss of the teabags within a 90 day incubation period. Weighed teabags were planted at a depth of 8cm and recovered after 3 months and reweighed. The study took place during winter and summer. This project also focused on different land use types: savanna, grassland and plantations that were in three Provinces in South Africa and these are Limpopo and Mpumalanga and Gauteng. This study found that there are complex interactions between litter quality, temperature, land use and soil properties, which result in the varying rates of decomposition. Litter quality played an important role in decomposition in this study, green tea with a higher labile fraction decomposed faster than Rooibos tea with a higher recalcitrant fraction. The different land use types have different soil properties and litter; these contribute to the varying litter decomposition rate constants found in the study. It was found that temperature has an effect on different land use types (temperatures between 15 °C–35 °C increase decomposition rate constants) however this study also found the importance of moisture on the temperature control of litter decomposition. Increased rainfall in summer from below 50mm in winter to above 100mm in summer increased decomposition rate constants. Any changes in rainfall and temperature in the future will impact decomposition rates. This study found decomposition rate constants ranging from 0.00183 to 0.01543 and stabilization values of 0.00327-0.79000. This study shows that changes in climate will have significant effects on soil carbon storage and decomposition rate constants in different biomes
Research report submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfilment of the requirements for the Master of Science (Coursework and Research Report in Environmental Sciences), February 2019