Seasonal patterns of greenhouse gas emissions from a forest‐to‐bog restored site in northern Scotland: Influence of microtopography and vegetation on carbon dioxide and methane dynamics

Abstract

Northern peatlands play an important role in the regulation of the atmospheric greenhouse gas (GHG) balance, functioning as a net carbon sink with low rates of organic decomposition. However, perturbations such as drainage increase peat oxidation, which may lead to enhanced gaseous release of carbon. For this reason, the number of restoration projects that aim to rewet blanket bogs has increased in the last few years, but there is still a lack of understanding of the impact of restoration on emissions of greenhouse gases, such as methane, particularly in sites restored from forestry. In this paper, we investigate the seasonal greenhouse gas dynamics in a forest‐to‐bog restoration site in Scotland. We analyse the effects of restoration on both carbon dioxide and methane fluxes, and investigate which site factors (microtopography, vegetation type, soil moisture and temperature) drive the processes of gaseous exchange between the bog surface and the atmosphere. Our results show that the original surface is near greenhouse gase equilibrium at −0.28 gCO2eq m2·day−1 and that microtopographic features act as a net greenhouse gas sink (ridges = −0.94 gCO2eq m2·day−1 and furrows = −0.86 gCO2eq m2·day−1), whereas the bog pool is a net source of greenhouse gases (0.98 gCO2eq m2·day−1). We found different vegetation species play a key role in greenhouse gas flux dynamics, especially in forestry‐derived microtopographical features, and their presence and influence on greenhouse gas dynamics should be accounted for to provide a more comprehensive understanding of emissions associated with restoration management practices.Highlights GHG (CO2 and CH4) dynamics in a boreal peatland restored from forestry are mainly affected by microtopography and vegetation. Forestry‐derived microforms (ridges and furrows) are better GHG sinks than pools (GHG emitters) and original surfaces (near GHG equilibrium). The presence of Trichophorum cespitosum leads to higher CH4 emissions. Restoration practices like terraforming may create a short‐term pulse net GHG emission due to an increase of both CH4 and CO2 fluxes.

Separating autotrophic and heterotrophic soil CO<sub>2</sub> effluxes in afforested peatlands

“…Afforestation of previously open peatlands in the British Isles (e.g. Mazzola et al, 2020) and Fennoscandia (e.g. Tolvanen et al, 2020) differ from other types of drained peatlands because this land-use change involves a wholesale shift in the functional composition of the plant community (i.e.…”

How does management affect soil C sequestration and greenhouse gas fluxes in boreal and temperate forests? – A review

“…In addition, the GHG emissions of forest-to-bog restorated peatlands in the UK were also examined. Results showed that the C sink function was successfully recovered after long-term restoration by felling trees and blocking ditches (16-17 years post-restoration; Creevy et al, 2020;Hambley et al, 2019;Mazzola et al, 2021). Whereas in the short-term, the restored sites were still a C source (less than 10 years after restoration), because while some were CO 2 sources (Hambley et al, 2019) and others sinks, the restored sites were consistently a strong source of CH (Creevy et al, 2020) or source of both GHGs (Rigney et al, 2018).…”

“…Whereas in the short-term, the restored sites were still a C source (less than 10 years after restoration), because while some were CO 2 sources (Hambley et al, 2019) and others sinks, the restored sites were consistently a strong source of CH (Creevy et al, 2020) or source of both GHGs (Rigney et al, 2018). Meanwhile, the C emissions of restored bogs largely depends on the vegetation composition (Creevy et al, 2020;Mazzola et al, 2021). A model of peatland photosynthesis at different stages after restoration suggested that the C assimilation capacity of a peatland can reach a nearpristine level 5-10 years after restoration (Lees et al, 2019).…”

Riparian Microtopography Affects Event‐Driven Stream DOC Concentrations and DOM Quality in a Forested Headwater Catchment

“…Several studies have investigated biogeochemical differences in relation to microtopographical heterogeneity (Courtwright & Findlay, 2011; Cresto Aleina et al., 2015; Diamond et al., 2021; Mazzola et al., 2021). Werner et al.…”

“…Several studies have investigated biogeochemical differences in relation to microtopographical heterogeneity (Courtwright & Findlay, 2011;Cresto Aleina et al, 2015;Diamond et al, 2021;Mazzola et al, 2021). Werner et al (2021) have recently shown that wet depressions contributed strongly to DOC export in the riparian zone of a forested catchment.…”