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Norwegian University of Science and Technology (NTNU) 2019

Teatime for termites : Understanding the impact of human land-use and climate on termite and microbial litter decomposition

Sundsdal, Anders

Titre : Teatime for termites : Understanding the impact of human land-use and climate on termite and microbial litter decomposition

Auteur : Sundsdal, Anders

Université de soutenance : Norwegian University of Science and Technology (NTNU)

Grade : Master’s thesis in Biology 2019

Résumé
Plant litter decomposition is a fundamental process underlying nutrient cycling and ecosystem productivity. Rates of decomposition in savannah ecosystems are dependent on both soil microbes and macrofauna, where termites are known to be important. However, little is known about how the balance between these decomposers is influenced by an increasing human dominated landscape. Here, we address this knowledge gap by investigating the contribution of microbes and termites to litter decomposition across three savannah land-uses : agricultural, pastural and wildlife protected areas in and around the Serengeti National Park, Tanzania. We used a selective mesh approach to contrast the impact of microbial and termite driven decomposition on a global standard litter types : labile green tea and recalcitrant rooibos tea, also known as the Tea Bag Index. Teabags were buried across the different land-uses in two contrasting rainfall regions and during both wet and dry seasons. Additionally, we established a common garden to assess how soil conditions influence the decomposition across land-uses and rainfall regimes. Overall, we found that microbes decompose the labile green tea to a far higher degree in the wet season and wet region, and that termites and other marofauna have little to no impact of labile litter decomposition. In contrast, the decomposition of the recalcitrant rooibos tea was strongly influenced by termites, in particular resulting in higher rates of decomposition in dry season and dry regions than microbial labile litter decomposition. Importantly, the contribution of termites and macrofauna was greatest in agricultural and pastural areas compared to wildlife protected areas during dry season. Through the use of the common garden we found no influence of soil properties on decomposition. These findings illustrate the importance of termites for the continuous nutrient cycling during dryer savannah conditions with an previously undervalued importance of macrofauna on human modified savannah landscapes.

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