Revealing sources of biological methane production in boreal upland forests


Boreal upland forest ecosystems are considered as sinks for the greenhouse gas methane (CH4) due to methane oxidizing bacteria (methanotrophs) in the soil. Recent evidence, however, suggest that boreal upland forest ecosystems may act as sources of CH4, and that the emissions from vegetation could largely overcome the sink strength of CH4 in upland forest soils. The mechanisms of the CH4 emissions from vegetation, and the partitioning of the CH4 fluxes between the forest-floor and the trees are, however, still largely unknown demonstrating our poor understanding of the CH4 sources and sinks in forest ecosystems.
The main aim of the project is to quantify the biological sources of CH4 in an upland boreal forest ecosystem, and to identify the microbes, CH4 producing methanogens, involved in the CH4 exchange in each of the compartments: soil, ground vegetation and trees. In order to quantify the contribution of each compartment to the net ecosystem CH4 exchange, the CH4 emission rates from the forest-floor, tree-trunks or the canopy (branches), will be integrated to represent the fluxes over a large forest area. The information of the microbial community structure and the presence of methanogens will be used to further understand the biological mechanisms and the players in the CH4 production.
Due to the unknown mechanisms and undefined sources of CH4 in boreal forests, this project has a great potential in bringing new insights to the understanding of CH4 dynamics in forest ecosystems. The knowledge of the role of trees and ground vegetation in the net CH4 fluxes of boreal forests will improve the process-based understanding, and can be utilized in modelling of CH4 dynamics in forest ecosystems.
In addition, this project brings together researchers from three different departments of the
University of Helsinki as well as other national and international partners, and it strengthens the role of dos. Mari Pihlatie as a group leader and an expert in methane cycling and biogeochemistry.
Effective start/end date31/10/201331/10/2016