Impacts of drainage, restoration and warming on boreal wetland greenhouse gas fluxes

Abstract

Northern wetlands with organic soil i.e., mires are significant carbon storages. This key ecosystem service may be threatened by anthropogenic activities and climate change, yet we still lack a consensus on how these major changes affects their carbon sink capacities. We studied how forestry drainage and restoration combined with experimental warming, impacts greenhouse gas fluxes of wetlands with peat. We measured CO and CH during two and NO fluxes during one growing season using the chamber method. Gas fluxes were primarily controlled by water table, leaf area and temperature. Land use had a clear impact of on CO exchange. Forestry drainage increased respiration rates and decreased field layer net ecosystem CO uptake (NEE) and leaf area index (LAI), while at restoration sites the flux rates and LAI had recovered to the level of undrained sites. CH emissions were exceptionally low at all sites during our study years due to natural drought, but still somewhat lower at drained compared to undrained sites. Moderate warming triggered an increase in LAI across all land use types. This was accompanied by an increase in cumulative seasonal NEE. Restoration appeared to be an effective tool to return the ecosystem functions of these wetlands as we found no differences in LAI or any gas flux components (PMAX, Reco, NEE, CH or NO) between restored and undrained sites. We did not find any signs that moderate warming would compromise the return of the ecosystem functions related to C sequestration.

Responses of peatland vegetation to 15‐year water level drawdown as mediated by fertility level

“…To assess the nature and rate of succession following moderate WLD for different plant communities representing microtopographical variation typical to northern peatlands (Rydin & Jeglum, 2013), the sample plots were divided into plant community groups based on pre-treatment bryophyte composition using Two-way Indicator Species Analyses (Hill & Šmilaur, 2005). We used bryophytes as the basis for clustering because unlike vascular plants they generally have a circumpolar distribution and their niche is highly specialised along microtopographical gradients (Laine, Mahtätalo, Tolvanen, Frolking, & Tuittila, 2018;Laine, Flatberg et al, 2018;Väliranta et al, 2007). Analysis was limited to four hierarchical levels (i.e., divisions) and a minimum of 10 plots per group.…”

Synchronous Growth Releases in Peatland Pine Chronologies as an Indicator for Regional Climate Dynamics—A Multi-Site Study Including Estonia, Belarus and Sweden

“…Peatland ecosystems are characterized by high soil moisture and partially decomposed vegetation accumulated as peat in soil layers [1]. Hydrological variability of peatlands depends on various climatic factors and affects peatland vegetation and carbon storage dynamics [2][3][4]. Even in their natural state, peatlands are considered complex and dynamic ecosystems, but peatland management or land-use changes may induce even more rapid shifts affecting local hydrology [1].…”

“…Assessing climatic effects on peatland hydrology is essential for evidence-based planning and management of peatlands for forestry (e.g., planning of ditch network maintenance) as well as peatland restoration, also considering climate mitigation and other ecosystem services. GWL is an important variable for modeling processes related to peatland ecology, hydrology, biogeochemistry, and greenhouse gas fluxes [3,4]. Continuous long-term instrumental series of GWL data from peatlands are very scarce, and there are few records as long-term as the records from Männikjärve bog in Estonia, which span from 1956 to the present [28].…”

Combination of Warming and Vegetation Composition Change Strengthens the Environmental Controls on N2O Fluxes in a Boreal Peatland

“…On the one hand, as a result of global warming, soil temperature will be increased, which can stimulate microbial activity and then increase the rate of decomposition [1]. On the other hand, global warming can increase the rate of photosynthesis [2]. Accordingly, the net effect of global warming on GHG emissions from peatlands depends on the balance between photosynthesis and decomposition.…”