Greenhouse gas emissions from rewetted and eutrophied fens: from carbon sink to source?

Fens are nutrient-poor wetlands characterized by active accumulation of organic plant matter (peat). This process requires waterlogged conditions and low microbial activity. Fens are important global sinks for atmospheric carbon dioxide (CO2), an important greenhouse gas (GHG). Unfortunately very few undisturbed fens remain, and most fens have been drained by human activity. Drainage triggers a myriad of cascading effects on fen biogeochemistry, vegetation and microbiology, and turns fens into sources of CO2. To make matters worse, fens are also increasingly threatened by nitrogen (N) enrichment. This may hamper peat formation, and could increase emissions of other potent GHGs such as methane (CH4) and nitrous oxide (N2O). The idea that degraded fens can quickly be restored by raising water levels seems naïve: recent observations suggest that rewetted fens often become nutrient-rich marshes. The effect of the drainage-rewetting cycle on GHG emissions is largely unknown, but might be dramatic. In this project, I will disentangle the interactive effects of fen hydrology and nitrogen enrichment on GHG emission. Moreover, I will investigate the influence of shifts in plant- and microbial community composition on altered GHG emissions. We hypothesize that drainage and N enrichment turn fens from sinks into sources of GHGs, and that this is partly due to shifts in plant- and microbial community composition. This change may be irreversible within human time-scales.

Keywords:PLANT ECOLOGY, BIOGEOCHEMISTRY

Disciplines:Biogeochemistry, Community ecology, Soil ecology, Microbiomes, Plant ecology

Project type:Collaboration project