The greenhouse gas (CO2 and CH4) exchanges in northern wetlands are affected by presence of vascular plants. The mechanisms at function are, however, largely unknown. The root adjacent zone is characterized by intense interactions between plants and their environment and many important processes relating to carbon turnover of ecosystems are taking place in this zone. A fairly large amount of the carbon assimilated by plants through photosynthesis is continuously released from the roots. These labile carbon compounds can serve as substrate for the methanogenic bacterial community of the root zone and have a substantial effect on CH4 production in the soil. Thus, even small environmental changes affecting root zone processes could have far-reaching consequences for the functioning of wetland ecosystem and their interaction with the atmosphere. The objectives of this project aim to broaden the existing knowledge about carbon circulation in wetlands.