Response of belowground carbon, sulphur and iron cycling in fen soils

气候模型预测，温带和北纬地区夏季干旱和强降雨会增加，这可能会改变湿地的水文和氧化还原机制，湿地是最重要的陆地碳储存。干旱和再湿润以及潜在的淹没对生态系统生产和地下碳循环的影响以及与氧化还原过程的耦合，特别是硫和铁的耦合，迄今尚未得到很好的理解。本项目将通过实验改变湿地的水文状况，并对其对碳循环的影响进行分析和模拟。为此，将在操作期间和操作后量化土壤含水量、温度和呼吸速率的变化。研究了相关的呼吸电子受体的可用性、生产和消耗，即氧气、硝酸盐、硫酸盐、铁和腐殖质物质，因为它们的动力学强烈影响甲烷的生产。一项实验室研究将用于分析一系列温度、干燥强度和持续时间对呼吸的影响。利用生态系统模型ECOSYS，将获得的数据与前期控制的中尺度和野外研究数据相结合，模拟水文变化对碳循环和甲烷动态的影响。该模型将在年代际尺度上模拟和分析干湿过程中生物地球化学过程的相互作用及其对碳循环的影响。

Climate models predict increases in summer drought and intensive rainfalls in temperate and northern latitudes, which may alter the hydrologic and redox regime of wetlands, the single most important terrestrial carbon storage. The impact of drying and rewetting and potential inundation on ecosystem production and belowground carbon cycling and the coupling with redox processes, in particular of sulfur and iron, is not well understood to date. In this project the hydrologic regime of a wetland will be altered experimentally and the consequences on carbon cycling be analyzed and simulated. To this end, changes in soil water contents, temperatures and respiration rates will be quantified during and after manipulation. The availability, production, and consumption of relevant electron acceptors for respiration, i.e. oxygen, nitrate, sulfate, ferric iron, humic substances, is studied, as their dynamics strongly influences methane production. A laboratory study will serve to analyze the impact of a range of temperatures and drying intensity and duration on respiration. The obtained data will be combined with the data of the previous controlled mesocosm and field study to simulate the impact of hydrologic change on carbon cycling and methane dynamics using the ecosystem model ECOSYS. The parameterized and tested model will be used to simulate and analyze the interaction of biogeochemical processes occurring during drying and rewetting and the impact on carbon cycling on the decadal time scale.