Peatland Sites Research Articles

Subtle changes in topsoil microbial communities of drained forested peatlands after prolonged drought.

A major consequence of anthropogenic climate change is the intensification and extension of drought periods. Prolonged drought can alter conditions in drained peatlands and cause disturbances in microbial communities in the topsoil layer of the peat. Varying environmental conditions throughout the growing season, such as the availability of organic matter and nutrients, temperature and water table, further impact these communities and consequently affect carbon and nutrient cycles. The impact of drought and new forestry practices is largely unknown in drained peatland forests. We examined how microbial communities change over a growing season in different harvesting intensities (continuous cover forestry, clear-cut and uncut) in a drained peatland site using bacterial 16S and fungal ITS2 rRNA analysis. We found seasonal differences in bacterial and fungal diversity and species richness, and subtle changes in microbial communities at the phylum and genus levels when comparing various environmental factors. Diversity, species richness and relative abundance differed in spring compared to summer and autumn. However, significant differences in the microbial community structure were not detected. Understanding the responses of microbial communities to disturbances like drought and other environmental factors provides new insights into the consequences of climate change on drained forested peatlands.

Carbon Storage and Fluxes from Sphagnum Peatlands of the Bogong High Plains, Australia

Australian alpine peatlands are critically important ecosystems that deliver a range of valuable services. However, our understanding of these services in Australia, particularly peatland carbon cycling, is lacking. Here, we quantified peat soil carbon (C) and nitrogen (N) concentrations, C:N ratios, and C density in eight Sphagnum-dominated peatlands on the Bogong High Plains, southeastern Australia. Soil C and N concentrations averaged 16.5 ± 13.2% and 0.6 ± 0.4%, respectively. C:N ratios averaged 30.9 ± 20.4, and C density averaged 46.6 ± 20.7 mg C cm− 3. Our findings suggest that (1) peat biogeochemistry is highly variable between sites, even at small spatial scales; and (2) while not a direct focus of the study, peat depths in this area were relatively shallow, ranging from 30 to 60 cm, most likely due to previous disturbance causing peat removal and carbon loss. Additionally, we present preliminary data investigating CO2 and CH4 fluxes at these sites. We recommend that future research includes (1) age dating peat cores to better understand the role of disturbance in rates of peat accumulation and loss; and (2) long-term carbon flux studies at multiple peatland sites.

GAMBUT field measurement of emissions from a tropical peatland fire experiment: from ignition to spread to suppression

Background Accurate quantification of emissions from peatland wildfire is crucial for understanding their feedback to the atmospheric and Earth system. However, current knowledge on this topic is limited to a few laboratory and field studies, which report substantial variability in terms of the fire emission factors (EFs). Aims We aim to understand how emissions vary across the life cycle of a peatland fire. Methods In August/September 2018, we conducted the largest and longest to-date field-scale experimental burn on a tropical peatland in Sumatra, Indonesia. Field measurements of gas emissions from the fire experiment were conducted using an open-path Fourier transform infrared spectroscopy to retrieve mole fractions of 11 gas species. Key results For the first time, we calculated and reported EFs from 40 measurement sessions conducted over 2 weeks of burning, encompassing different fire stages (e.g. ignition, smouldering spread, and suppression) and weather events (e.g. rainfall). Our findings provide field evidence to indicate that EFs vary significantly among fire stages and weather events. We also observed that the heterogeneous physicochemical properties of peatland site (e.g. moisture content) influenced the EFs. We also found that modified combustion efficiency was highly sensitive to complex field variables and could introduce large uncertainties when determining the regimes of a peat fire. Conclusions and implications Further studies to investigate peat fire emissions are needed, and more comprehensive mapping of peatland heterogeneity and land use for emissions inventories, accounting for spatial and temporal variability in EFs since the initiation of a fire event is required.

Are pools created when restoring extracted peatlands biogeochemically similar to natural peatland pools?

In the last 25 years, several degraded peatlands in eastern Canada have been restored toward their natural structure. Pools are common in natural peatlands and are important habitats for unique flora and fauna. Because of their ecological value, pools have been created in some restored peatland sites. Nevertheless, the biogeochemistry of created pools in a restoration context has seldom been studied. The objective of our study is to characterize the biogeochemistry of created pools from restored peatlands and compare them with natural pools along a chronosequence since their creation. We measured different biogeochemical variables (pH, concentrations of nitrogen (N), phosphorus (P), dissolved organic carbon (DOC), dissolved organic matter (DOM), base cations-calcium (Ca), sodium (Na), magnesium (Mg), and potassium (K)-and dissolved gases-methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O)-) in 61 pools distributed over seven peatlands in eastern Canada. The sites represent a range of conditions, from natural to restored peatlands with pools ranging from 3 to 22 years old. Created and natural pools had distinctive biogeochemistry, with created pools being generally less acidic (pH >5) and 2.5 times more concentrated in nutrients (N and P) than in natural pools. DOC, N, P, dissolved gases, and base cations concentrations were lower in natural pools than in created pools, and varied between created sites. The oldest created pools (age >17 years) tend to approach the biogeochemical characteristics of natural pools, indicating that created pools may, over time, provide habitats with similar conditions to natural pools. A return of created pools to a natural pool-like biogeochemistry could thus inform on the success of peatland restoration.

A Low-Cost Sensor Network for Monitoring Peatland.

Peatlands across the world are vital carbon stores. However, human activities have caused the degradation of many sites, increasing their greenhouse gas emissions and vulnerability to wildfires. Comprehensive monitoring of peatlands is essential for their protection, tracking degradation and restoration, but current techniques are limited by cost, poor reliability and low spatial or temporal resolution. This paper covers the research, development, deployment and performance of a resilient and modular multi-purpose wireless sensor network as an alternative means of monitoring peatlands. The sensor network consists of four sensor nodes and a gateway and measures temperature, humidity, soil moisture, carbon dioxide and methane. The sensor nodes transmit measured data over LoRaWAN to The Things Network every 30 min. To increase the maximum possible deployment duration, a novel datastring encoder was implemented which reduced the transmitted datastring length by 23%. This system was deployed in a New Forest (Hampshire, UK) peatland site for two months and collected more than 7500 measurements. This deployment demonstrated that low-cost sensor networks have the potential to improve the temporal and spatial resolution of peatland emission monitoring beyond what is achievable with traditional monitoring techniques.

Hyperspectral characterization of vegetation in hemiboreal, boreal and Arctic peatlands using a geographically extensive field dataset

Northern peatlands store up to 25% of global soil organic carbon and function as important hotspots for biodiversity. However, they are facing degradation from climate change driven by human activities as well as anthropogenic land use changes, up to the point of endangering the ecosystems' functioning and the storage of soil organic carbon entailed within them. The surface vegetation of northern peatlands is an important indicator of the ecosystem's functioning and ecohydrology, highlighting the importance of its large-scale, continuous monitoring. Approaches utilizing hyperspectral data for monitoring vegetation health and species composition can also be applied to peatland vegetation. To support the development of methods for interpreting hyperspectral satellite data from peatlands, we conducted a comprehensive in situ study of hemiboreal, boreal, sub-Arctic and Arctic peatland vegetation. We measured the reflectance spectra (350–2500 nm), soil moisture, and various vegetation-related attributes from a total of 446 vegetation plots in Estonia and Finland, from a 1500 km south-north interval. We then investigated (i) the spectral variation in surface vegetation of hemiboreal, boreal, sub-Arctic and Arctic peatlands and (ii) explored its connection to plant functional types (PFTs) and soil moisture, as well as evaluated the potential of hyperspectral data in estimating PFT cover using simple vegetation indices and partial least square (PLS) regression. Our results indicate that (i) the best spectral regions to retrieve information regarding the PFT vary greatly especially between vascular plants and bryophytes, (ii) the reflectance at an individual wavelength as well as simple vegetational index can, to some extent, predict the PFT, and that (iii) the PLS regression can predict the PFT with good accuracy. Overall, our findings demonstrate the potential of using hyperspectral data in monitoring PFTs in northern peatlands. The spectral library and the ancillary data from the peatland sites collected for this study are available as open data.

Net primary productivity and litter decomposition rates in two distinct Amazonian peatlands.

Measurements of net primary productivity (NPP) and litter decomposition from tropical peatlands are severely lacking, limiting our ability to parameterise and validate models of tropical peatland development and thereby make robust predictions of how these systems will respond to future environmental and climatic change. Here, we present total NPP (i.e., above- and below-ground) and decomposition data from two floristically and structurally distinct forested peatland sites within the Pastaza Marañón Foreland Basin, northern Peru, the largest tropical peatland area in Amazonia: (1) a palm (largely Mauritia flexuosa) dominated swamp forest and (2) a hardwood dominated swamp forest (known as 'pole forest', due to the abundance of thin-stemmed trees). Total NPP in the palm forest and hardwood-dominated forest (9.83 ± 1.43 and 7.34 ± 0.84 Mg C ha-1 year-1, respectively) was low compared with values reported for terra firme forest in the region (14.21-15.01 Mg C ha-1 year-1) and for tropical peatlands elsewhere (11.06 and 13.20 Mg C ha-1 year-1). Despite the similar total NPP of the two forest types, there were considerable differences in the distribution of NPP. Fine root NPP was seven times higher in the palm forest (4.56 ± 1.05 Mg C ha-1 year-1) than in the hardwood forest (0.61 ± 0.22 Mg C ha-1 year-1). Above-ground palm NPP, a frequently overlooked component, made large contributions to total NPP in the palm-dominated forest, accounting for 41% (14% in the hardwood-dominated forest). Conversely, Mauritia flexuosa litter decomposition rates were the same in both plots: highest for leaf material, followed by root and then stem material (21%, 77% and 86% of mass remaining after 1 year respectively for both plots). Our results suggest potential differences in these two peatland types' responses to climate and other environmental changes and will assist in future modelling studies of these systems.

Reviews and syntheses: A scoping review evaluating the potential application of ecohydrological models for northern peatland restoration

Abstract. Peatland restoration and rehabilitation action has become more widely acknowledged as a necessary response to mitigating climate change risks and improving global carbon storage. Peatland ecosystems require restoration time spans of the order of decades and, thus, cannot be dependent upon the shorter-term monitoring often carried out in research projects. Hydrological assessments using geospatial tools provide the basis for planning restoration works as well as analysing associated environmental influences. “Restoration” encompasses applications to pre-restoration and post-restoration scenarios for both bogs and fens, across a range of environmental impact fields. The aim of this scoping review is to identify, describe, and categorize current process-based modelling uses in peatlands in order to investigate the applicability and appropriateness of ecohydrological and/or hydrological models for northern peatland restoration. Two literature searches were conducted using the entire Web of Science database in September 2022 and August 2023. Of the final 211 papers included in the review, models and their applications were categorized according to this review's research interests in seven distinct categories aggregating the papers' research themes and model outputs. Restoration site context was added by identifying 229 unique study site locations from the full database, which were catalogued and analysed against raster data for the Köppen–Geiger climate classification scheme. A majority of northern peatland sites were in temperate oceanic zones or humid continental zones that experienced snow. Over one in five models from the full database of papers were unnamed and likely intended for single use. Key themes emerging from topics covered by papers in the database included the following: modelling restoration development from a bog growth perspective, the prioritization of modelling greenhouse gas (GHG) emissions dynamics as a part of policymaking, the importance of spatial connectivity within or alongside process-based models to represent heterogeneous systems, and the increased prevalence of remote sensing and machine learning techniques to predict restoration progress with little physical site intervention. Models are presented according to their application to peatlands or broader ecosystem and organized from most to least complex. This review provides valuable context for the application of ecohydrological models in determining strategies for peatland restoration and evaluating post-intervention development over time.

Climate change mitigation potential of restoration of boreal peatlands drained for forestry can be adjusted by site selection and restoration measures

Peatland restoration is seen as a key nature‐based solution to tackle climate change and biodiversity loss. In Europe, nearly 50% of peatlands have been drained during the last decades, which have shifted their soils to carbon dioxide (CO2) sources. Soils of forestry‐drained peatlands are known to vary from CO2 sources to small sinks depending on their fertility and wetness. When peatlands are restored, it can be expected that rates of CO2 and methane exchange will vary depending on site fertility and wetness. We generated seven restoration pathways with different starting and end points and assessed the climate impacts of them. The GHG emission coefficients were compiled from literature, and radiative forcing was calculated for a 500‐year time period since restoration. All seven restoration pathways improved carbon sink capacity; however, the climate impact differed from cooling to warming. The highest cooling impact occurred in a pathway leading from nutrient‐rich drained peatlands toward tree‐covered spruce or pine mires. Warming impacts occurred in a pathway leading from nutrient‐poor drained peatlands toward open peatlands. The results of this study can be used to help identify peatland sites and restoration targets to maximize climate change mitigation from restoration. In practice, however, restoration has to fulfill other targets, such as biodiversity safeguarding, improvement of hydrological conditions, and socio‐economic aspects. Fulfilling all targets simultaneously requires compromises on all targets.

Ash fertilization increases long-term timber production in drained nitrogen-poor Scots pine peatlands

Wood ash fertilization remarkably increases tree growth and hence, carbon sequestration in drained boreal peatland forests, particularly in nitrogen (N)-rich Scots pine sites with limited phosphorus (P) and potassium (K). Because ash lacks N, N-deficient ombrotrophic and poor oligotrophic sites are generally considered unsuitable for ash fertilization. In this study, timber production was investigated in six field experiments in N-poor, drained Scots pine dominated peatlands in central Finland, where ash fertilization was applied 15–85 years earlier. Ash significantly increased tree growth in all the study sites. Unfertilized plots showed long-term average mean annual increment (MAI) of 2.01 m3·ha−1·a−1, whereas in fertilized plots MAI was 4.46 m3·ha−1·a−1. An analysis with nonlinear mixed effects model revealed a faster volume yield development and higher asymptote of the mean curve in fertilized plots. Higher amount of K in the ash significantly increased the response. Fertilizations were financially lucrative: on average, the break-even cost surpassed the ash fertilization cost (390 € ha−1) more than two-fold at 5% interest rate. The current nutrient status of fertilized trees was rather balanced. The results proved that the long-term growth response to ash fertilization in poor drained peatland sites is comparable to N-rich sites, but the response time is distinctively longer.

Long‐Term Response of Peatland Carbon Exchange to Climatic Changes in the Hudson Bay Lowlands

AbstractNorthern peatlands have been a persistent net sink of atmospheric carbon (C) due to the greater rates of gross primary production (GPP) compared to ecosystem respiration (ER). Global warming has raised concerns about the C sink strength of northern environments. In the vast peatlands of the Hudson Bay Lowlands (HBL) region of Canada, warming‐induced changes in sea ice dynamics over the Bay have altered its advective influence on the adjacent lowlands. Despite our knowledge of the short‐term C exchange in these peatlands, there remain uncertainties in the long‐term combined response of GPP and ER to climate change. In this study, the satellite‐data‐driven Vegetation Photosynthesis and Respiration Model was employed to investigate the response of peatland GPP, ER, and net ecosystem exchange to temperature and moisture changes. The results show contrasting net CO2 exchange at the two peatland sites over the last 20 years, with the fen acting as a net C source (+24 g C m−2) to the atmosphere and the bog serving as a net C sink (−130 g C m−2). There is ample evidence that a warmer and wetter climate enhanced GPP more than ER, while cooler temperatures weakened the peatland net C sink, regardless of the moisture conditions. Additionally, the advective influence of Hudson Bay on the lowlands produced markedly different C dynamics between offshore and onshore winds, with higher respiration rates (12%–26%) during offshore winds. We discuss the implications for peatland C balance under more frequent onshore winds in the region.

Poetic inquiry to explore the relational values of a transforming peat landscape

Abstract Restoring degraded peatlands is a promising strategy for mitigating carbon emissions. Large‐scale landscape transformations, such as rewetting of land used for intensive agriculture, often lead to conflicts. Elicitation of the relational values acting as barriers to landscape transformation may support the resolution or taming of such conflicts. This study aimed to explore the relational values associated with a transforming peatland site in Northern Germany. We focused on the value of living and non‐living peat landscape elements; cultural heritage values and identities; educational values; spiritual values; recreational values; and sensory, affective and cognitive experiences. Additionally, we sought to understand how past landscape changes have influenced these values. We conducted interviews with land managers and local residents. Using an art‐based research method, we created six thematic participant‐voiced poems that capture the diverse peatland values. Subsequent interpretation of these poems revealed three key observations: the importance of multisensory experiences; the significance of specific living elements; and the deep cultural and historical values linked to peat landscapes. Landscape changes impact peat landscape values, potentially weakening bonds between people and the peatland. Our study indicates that considering the cultural and historical significance of landscapes may prevent conflicts and foster support for peatland restoration. Ensuring the well‐being of those living and working in these areas requires value‐inclusive landscape planning that embraces a broader focus on relational values. This also involves the potential promotion of value shifts. Such an approach may cultivate a more sustainable and inclusive transformation of the landscape. Read the free Plain Language Summary for this article on the Journal blog.

Restructuring of soil food webs reduces carbon storage potential in boreal peatlands

Microbial and faunal decomposers regulate the flux of carbon and nitrogen belowground, thus controlling the storage/release of carbon and nitrogen in soil systems. Warming is anticipated to alter decomposer biomass, and accelerate organismal metabolism and soil carbon release. We parameterized six soil food webs using empirical data for 18 trophic nodes at two boreal peatland sites under three climate scenarios (control, +2 °C, +4 °C), and model carbon and nitrogen flux, loss and retention using an energetic ecostoichiometric food web model. Differences in microbial biomass between sites dictated flux under warming. The community biomass of the fungal-dominated site was more impacted by warming, but fluxes were more responsive to warming at the bacterial-dominated site. Decreased metabolic efficiency of the soil food web at both sites in response to warming led to greater per capita carbon losses, indicating the long-term carbon storage potential of both systems is diminished.

Temporally dynamic carbon dioxide and methane emission factors for rewetted peatlands

Rewetting drained peatlands is recognized as a leading and effective natural solution to curb greenhouse gas emissions. However, rewetting creates novel ecosystems whose emission behaviors are not adequately captured by currently used emission factors. These emission factors are applied immediately after rewetting, thus do not reflect the temporal dynamics of greenhouse gas emissions during the period wherein there is a transition to a rewetted steady-state. Here, we provide long-term data showing a mismatch between actual emissions and default emission factors and revealing the temporal patterns of annual carbon dioxide and methane fluxes in a rewetted peatland site in northeastern Germany. We show that site-level annual emissions of carbon dioxide and methane approach the IPCC default emission factors and those suggested for the German national inventory report only between 13 to 16 years after rewetting. Over the entire study period, we observed a source-to-sink transition of annual carbon dioxide fluxes with a decreasing trend of −0.36 t CO2-C ha−1 yr−1 and a decrease in annual methane emissions of −23.6 kg CH4 ha−1 yr−1. Our results indicate that emission factors should represent the temporally dynamic nature of peatlands post-rewetting and consider the effect of site characteristics to better estimate associated annual emissions.

Impact of Large-Scale Fire and Habitat Type on Ant Nest Density and Species Abundance in Biebrza National Park, Poland

Fire can have negative effects on the ant community by reducing species abundance through direct mortality, changes in resource availability, or foraging activity. Fire can also have positive effects, especially for opportunistic species preferring open or disturbed habitats. We assessed the direct effects of a large-scale fire on ant communities in open habitats (grassland and Carex) and moist forested peatland (birch and alder) sites in Biebrza National Park, testing three hypotheses: (i) the large-scale fire had more significant effects on ant nest density in forests than in open habitats, (ii) the post-fire ant diversity changes within sites are stronger in forests than open habitats, and (iii) ant species preferring disturbed habitats are favoured by the fire event. The fire had negative effects on ant nest density only in the Carex and grassland sites but not in the birch and alder sites, suggesting that fire had a stronger impact in open habitats than in forests. Temporal post-fire ant diversity changes within sites were stronger in forests than in open habitats. We observed higher beta diversity changes between the first and second year of the study in the burned forest sites due to colonisation, indicating a greater fire impact on species community composition followed by a higher recolonisation rate. Ant species preferring disturbed habitats were favoured by the fire. The seed-eating ant species Tetramorium caespitum, a thermophilous and opportunistic species, dominated the burned grassland site. This contrasts with other species, e.g., Lasius alienus, for which nest density decreased after fire, underlining the importance of food resource availability as a major driver of community changes after fire. Our study also underlines the importance of periodic biodiversity monitoring in conservation areas for assessing the recovery of the original status after disturbances and revealing possible habitat changes endangering the survival of local biotic communities.

Redox potential is a robust indicator for decomposition processes in drained agricultural peat soils: A valuable tool in monitoring peatland wetting efforts

Peat decomposition driven by soil metabolic processes is responsible for approximately 2 % of global annual anthropogenic greenhouse gas emissions. A peat soil's redox potential (Eh) and pH reflect its biogeochemical state and are therefore linked to the rate of peat decomposition and greenhouse gas production. In this study, we aim to establish if continuous Eh measurements are an effective tool to monitor metabolic peat decomposition processes and thus to quantify the effects of peat wetting efforts. We applied continuous in-situ Eh measurements (>150 sensors 2020–2022) as a proxy for metabolic peat decomposition processes, which we validated under field conditions with extensive sampling of porewater chemistry (pH, NO3–, SO42−, Mn(II), Fe(II), S2− and CH4, >2000 samples) for five agricultural, drained, minerotrophic peatland sites in the Netherlands. These 5 sites consisted of plots with and without subsoil irrigation (SSI), where SSI aims to raise groundwater levels and thus wet the peat soil. We found that in-situ continuous Eh measurements closely reflected spatial and temporal heterogeneity in pore water chemistry. Therefore, we concluded that Eh is a robust proxy for peat decomposition processes. Building on this result, we used continuous Eh measurements to study the prevalence of specific metabolic processes from site-to-site in relation with groundwater level changes. We found that, while groundwater levels are an important driver for (an)aerobic conditions, groundwater levels do not explain the full dynamics and extent of (an)aerobic conditions. O2 intrusion was mostly limited to approximately 0.5 m depth at deep (>0.8 m) groundwater levels, likely due to air diffusion limitation. Higher and more constant groundwater levels year-round at SSI plots decreased oxygen intrusion and tended to deplete porewater Fe(II) and SO42−, which led to more reducing Eh and higher porewater CH4 concentrations. The depletion of electron acceptors and occurrence of methanogenesis differed from site to site. In summary, high-frequent Eh monitoring is found to be an effective tool to monitor metabolic peat decomposition processes and quantify the effects of peatlands wetting efforts. Therefore, this methodology is suitable to evaluate and further optimize peatland monitoring and preservation.

Peatland-VU-NUCOM (PVN 1.0): using dynamic plant functional types to model peatland vegetation, CH4, and CO2 emissions

Abstract. Despite covering only 3 % of the planet’s land surface, peatlands store 30 % of the planet’s terrestrial carbon. The net greenhouse gas (GHG) emissions from peatlands depend on many factors but primarily soil temperature, vegetation composition, water level and drainage, and land management. However, many peatland models rely on water levels to estimate CH4 exchange, neglecting to consider the role of CH4 transported to the atmosphere by vegetation. To assess the impact of vegetation on the GHG fluxes of peatlands, we have developed a new model, Peatland-VU-NUCOM (PVN). The PVN model is a site-specific peatland CH4 and CO2 emissions model, able to reproduce vegetation dynamics. To represent dynamic vegetation, we have introduced plant functional types and competition, adapted from the NUCOM-BOG model, into the framework of the Peatland-VU model, a peatland GHG emissions model. The new PVN model includes plant competition, CH4 diffusion, ebullition, root, shoot, litter, exudate production, belowground decomposition, and aboveground moss development under changing water levels and climatic conditions. Here, we present the PVN model structure and explore the model's sensitivity to environmental input data and the introduction of the new vegetation competition schemes. We evaluate the model against observed chamber data collected at two peatland sites in the Netherlands to show that the model is able to reproduce realistic plant biomass fractions and daily CH4 and CO2 fluxes. We find that daily air temperature, water level, harvest frequency and height, and vegetation composition drive CH4 and CO2 emissions. We find that this process-based model is suitable to be used to simulate peatland vegetation dynamics and CH4 and CO2 emissions.

Waterlogging may reduce chemical soil C stabilization in forested peatlands

Boreal forested peatlands are globally significant carbon (C) pools where soil water-table level largely controls decomposition rate. Here we aimed to investigate the contrarian hypothesis that waterlogging conditions do not lead to increased C stabilization in a forested peatland. We studied how waterlogging affects root and soil chemistry, fungal biomass and necromass, C pools, soil enzyme activities and fungal community composition in Pinus sylvestris rhizosphere. Samples were collected from 0–10 cm, 10–20 cm and 20–30 cm soil layers in a controlled-environment experiment with waterlogging and control treatments and in two forested peatland sites, wetter and drier. Tannin content, live fungal biomass, enzyme activities, and chemically stable SOC content and its proportion of total SOC content were generally lower in waterlogged than control treatment in the experiment, and lower in the wetter than the drier site. The proportion of ectomycorrhizal fungi was higher in the drier than the wetter site in the deepest soil layer studied, 20–30 cm. In the wetter site, chemically stable SOC content and proportion of ericoid mycorrhizal fungi were highest in topsoil that contained more roots than deeper soil layers. In conclusion, forested peatlands possess specific root-related chemical SOC stabilization mechanisms, and, consequently, waterlogging makes their SOC more vulnerable due to decreased chemical C stabilization via root-microbial interactions and lowering root production.

A Study of Dominant Vegetation Phenology in a Sphagnum Mountain Peatland Using In Situ and Sentinel‐2 Observations

AbstractPeatlands store more than a third of the global soil organic carbon stock. Bryophytes, more specifically Sphagnum mosses, play a major role in the carbon and water cycles of these ecosystems. There is a need to include Sphagnum mosses into Earth system models to better simulate the dynamics of peatlands in a changing environment. Leaf area index (LAI) is a key plant trait that characterizes the plant photosynthesizing capacity. Moreover, LAI is a variable calculated by land surface models used in climate models, allowing control of the exchange of matter and energy between vegetation and the environment. There is extremely little data on Sphagnum LAI and none on its seasonal change. We monitored Sphagnum mosses LAI phenology in a mountainous peatland site (altitude of 1,343 m) from June to December 2021 using two methods: 2D scans of monthly Sphagnum moss samples and analysis of Sentinel‐2 images. LAI derived from field campaigns and the remote sensing approach show a strong seasonality, with high peak values reaching 10 and 7 m2·m−2, respectively. The Sentinel‐2 images were also used to derive common vegetation indices. The moisture soil index effectively discriminates Sphagnum‐dominated areas in the peatland. Satellite‐derived LAI of Sphagnum mosses is directly correlated to gross primary production monitored by gas exchange measurements (R2 = 0.83) but also to physical drivers of the environment such as air temperature (R2 = 0.74) or water table depth (R2 = 0.61) over the 2017–2021 period. It is therefore highly suitable to investigate ecosystemic functions.

Potential of continuous cover forestry on drained peatlands to increase the carbon sink in Finland

Land-based mitigation measures are needed to achieve climate targets. One option is the mitigation of currently high greenhouse gas (GHG) emissions of nutrient-rich drained peatland forest soils. Continuous cover forestry (CCF) has been proposed as a measure to manage this GHG emission source; however, its emission reduction potential and impact on timber production at regional and national scales have not been quantified. To quantify the potential emission reduction, we simulated four management scenarios for Finnish forests: (i) The replacement of clear-cutting by selection harvesting on nutrient-rich drained peatlands (CCF) and (ii) the current forest management regime (BAU), and both at two harvest levels, namely (i) the mean annual harvesting (2016–2018) and (ii) the maximum sustainable yield. The simulations were conducted at the stand scale with a forest simulator (MELA) coupled with a hydrological model (SpaFHy), soil C model (Yasso07) and empirical GHG exchange models. Simulations showed that the management scenario that avoided clear-cutting on nutrient-rich drained peatlands (i.e. CCF) produced approximately 1 Tg CO2 eq. higher carbon sinks annually compared with BAU at equal harvest level for Finland. This emission reduction can be attributed to the maintenance of a higher biomass sink and to the mitigation of soil emissions from nutrient-rich drained peatland sites.