Terrestrial Si dynamics in the Arctic: a study on biotic and abiotic controls

摘要: Silicon is the next most abundant element in Earth’s crust and its biogeochemical cycle linked with that of carbon. Further, silicon a beneficial nutrient for plants terrestrial ecosystems key diatoms aquatic ecosystems. During last decade important role vegetation controlling Si fluxes downstream environments, via incorporation into biomass (as amorphous Si) subsequent storage soil, has been realized. Due to high prevalence Si-accumulating plants, cold temperatures perenially frozen soil conditions, Arctic hypothesized store significant fraction global ASi stock. The environment highly sensitive climate change, unknown effects cycling. Hence, this thesis we utilized archived samples collected from different geographical regions tundra continuous permafrost region. By combining results obtained through chemical analysis literature review provide conceptual framework how change may alter biological component cycling underlain by permafrost. thaw can mobilize previously material initiating processing newly thawed material, such as dissolution plant derived silica stored soil. Hence, an additional aspect shed light on potential biotic control (i.e. microbial influence) rates during litter degradation. This question was explored utilization microcosm laboratory experiments. Dependent land cover type, found total range between 1,030 - 94,300 kg SiO2 ha-1 shrub/graminoid peatland first estimate (0 1 m) northern circumpolar presented thesis. Our estimates, based upscaling classes estimated 219 510 Tmol Si, which represents 2 6 % storage. also show majority allocated mineral subsoil, indicating pedogenic rather than biogenically fractions dominate pool Arctic. Furthermore, suggest at least 30 layer, thus potentially representing will become available future warmer Arctic. Regarding influence microbes (bacteria fungi) decomposition, find reduce apparent release reduction increases greater colonization decomposition litter. result contrary predicted common beliefs enhance decomposition). While work carried out herein do not allow exact mechanism behind pattern be resolved, indicate availability released Si. Overall, fills some existing knowledge gaps regarding size geographical/landscape distribution pool, significance context well were understudied.