In every warm region of the world, a huge proportion of biomass is converted to soil by termites. Besides this well-known fact, however, the global-scale contribution of termites to organic matter cycling has not been quantified. Our team will estimate the contributions of termites and their manifold environmental-engineering activities to some of the most fundamental processes of Earth’s ecosystems, specifically soil formation and carbon dioxide release. Going beyond the insect level, we will also use a series of experiments to estimate the contribution of the termites’ symbiotic microorganisms, and document the composition and function of these communities along a decomposition gradient. We aim to convey a comprehensive, global picture, by conducting the sampling in the Afrotropics (Cameroon), the Neotropics (French Guiana), the Indomalayan (south China) and the Australasian (Papua New Guinea) ecozones, and thus focusing on the most productive terrestrial biotopes on Earth.
To discriminate and quantify the roles of termites, their allied microbial consortia, and environmental factors in organic matter recycling, we will deploy a hierarchical design of field and lab experiments. Our approaches comprise quantification of the production of plant matter and its decomposition by means of termite actions, metabarcoding of microbial communities in comparable environmental samples and standard sterile wood and soil baits with and without access of termites, transcriptomic approaches in environmental samples, cultivated microorganisms and termite guts, genome and metagenome sequencing of selected termites and their symbionts, as well as laboratory assays disentangling decomposition capacities of particular termites and microorganisms and influence of xenochemicals upon the degradation processes. The combined evidence will allow us to test four fundamental hypotheses, which are as follows: (A) Does pre-digestion microbial management support termite impact on biodegradation? (B) Do the interactions between termites and microbiota differ at two fundamental levels, and are endosymbionts inherited strictly vertically while ectosymbionts origin from the pool of local microbes? (C) Do specific termite-associated microbes or fungi, rather than environmental factors, facilitate the termite-driven degradation, and are the patterns of co-evolution evidenced at genome level? (D) Do selected xenochemicals, nutrients or biocides, support or suppress particular strains of microorganisms, and are the community changes reflected by enhanced or decreased decomposition rates?