Linking vegetation, peat and gas exchange to assess whether mires in certain climate scenarios, could have the potential to provide natural climate change mitigation.

The central question in the research project FORCE is how mire vegetation (peat producing vegetation) is related to intake and release of carbon. The northern peatlands (ecosystems with peat thicker than 30-40 cm) have during thousands of years built up peat layers that store massive amounts of carbon – equivalent to half the amount in the atmosphere. As the climate is warming, more peat may be stored in peatlands. 

We are asking, which factors, such as plant species, traits, or peat characteristics, drive the development of the mire types that store more carbon?

Succession through ecosystem engineering

Ombrotrophication is a natural succession process where the living vegetation on the surface of the mire becomes isolated from mineral-rich ground water by a progressively thicker layer of peat. Peat consists of dead plant material that hasn’t decomposed much – instead a lot the carbon that the plants collect from the atmosphere during photosynthesis is stored in the peat. The plant species change as this process goes on, and species of plants that better endure these increasingly harsh conditions will take over; one community succeeds the other. Species that prosper here, such as mosses in the genus Sphagnum, promote conditions that deter others and suit themselves; they are engineering the ecosystem through their traits, such as producing peat that decomposes slowly.  

Effects of the Norwegian climate scenario

The climate scenario for some places, for example for Trøndelag, is that it will be warmer and wetter. We think that such conditions could result in an acceleration of the ombrotrophication, because plants will grow faster in warmer conditions, and the wetter conditions would result in lower decomposition of the peat. We want to test this hypothesis in a peatland in Trøndelag by measuring how the peatland at different stages of succession towards ombrotrophication, release and take up greenhouse gases, and how plants and traits are related to this. 

Gas exchange of a Trøndersk mire

During the growing season of 2023 we will study how much of different greenhouse gases are released and captured at three points along an ombrotrophication gradient, to help us answer questions about the carbon balance in these differing conditions. Simultaneously we will monitor the vegetation, and measure plant traits. Also, the hydrology – the water flow through the ecosystem – will be monitored throughout the system by the collaborators from the Polish part of the FORCE project, from the University of Warsaw. 

Is the peat different in different climates?

The plants that end up as peat, and the conditions where the peat forms might have different effects on the stability of the peat. To look further into the decomposability of the peat, we are studying how easily peat decomposes when it comes from more ombrotrophic versus less ombrotrophic conditions, and how this is affected by the plants that grow just above the peat. Furthermore, to investigate whether the climate affects the peat quality, we sampled the varyingly ombrotrophic peat from a wide climatic gradient, reaching from Finnmark above the polar circle in Norway, to Poland. We are measuring how easily the peat decomposes by putting the peat samples in jars, where we track how much carbon they release over time. In the field, we collected data on which plant species (mosses and vascular plants) that grew just on top of those peat samples, to reveal relationships between vegetation and peat stability.