The rapid, effective restoration of degraded peatlands is urgently needed to reduce their current high levels of carbon loss. The re-introduction of Sphagnum moss, along with re-wetting, is key to returning carbon sequestration and retention capabilities to northern degraded bogs. Micropropagated Sphagnum has already been applied in large quantities, and more is planned, for restoration projects in Britain and parts of Europe. A comparison with wild-sourced Sphagnum material is therefore pertinent to demonstrate its safety and suitability for wide-scale application. Six Sphagnum species of both micropropagated and wild-sourced origin were assessed for photosynthetic capacity, nutrient content, form parity, chlorocyst size, and chloroplast numbers. Micropropagated Sphagnum had significantly higher light-saturated photosynthesis (Pmax) rates, little color expression, an open growth habit, greater chloroplast numbers, and more numerous, smaller shoot apices than wild-sourced Sphagnum. Higher Pmax rates were associated with a lower bulk density and higher tissue nutrient concentrations. Potentially, greater chloroplast numbers in micropropagated Sphagnum facilitate higher photosynthesis rates, driving rapid growth in early-stage plants, particularly in optimum moisture conditions. Micropropagated Sphagnum can be used confidently, propagated in large quantities, and will likely establish well on application to sites where re-wetting has already occurred, therefore making it highly beneficial for the restoration of degraded bogs.

Degraded peatlands are significant sources of carbon greenhouse gases (CGHG), and their recovery can make significant contributions to climate change mitigation as well as deliver biodiversity benefits. Sphagnum mosses are key species for northern peatland formation and re-introduction is often needed for successful ecohydrological restoration of degraded bogs, but natural sources are scarce and often protected. Micropropagated Sphagnum moss products (BeadaMoss®) were developed to alleviate this constraint. This research explored in detail, for the first time, the CGHG fluxes on a cut-over lowland peatland restoration site where micropropagated Sphagnum was introduced to an existing ‘nurse crop’ of Eriophorum angustifolium, and tested the influence of vegetation maturity. Ecosystem CGHG flux was measured using closed chambers at plot scale in areas of both mature and immature E. angustifolium with and without application of BeadaGel™ Sphagnum, with control plots on bare peat. Studies were conducted over two years of contrasting weather patterns. In Year 1, mean net (CO2e) CGHG uptake on vegetated plots was -2.33 (minimum 1.55, maximum 5.55) t ha-1 yr-1 with increasing CGHG uptake as vegetation matured. In Year 2, gross photosynthesis reduced significantly during the 2018 summer drought resulting in a small mean net CGHG emission of 0.11 (minimum 2.21 maximum -1.22) t ha-1 yr-1. Sphagnum application within immature vegetation resulted in greater CGHG uptake in both years, but was not as beneficial within mature vegetation. CGHG emission from bare peat (3.79 t ha-1 yr-1 overall) showed the magnitude of avoided losses. Methane flux contributed significantly to CGHG emission but was not closely related to water table depth. Application of Sphagnum within E. angustifolium can deliver good CGHG flux results in the early stages of degraded lowland bog recovery but cannot fully mitigate vulnerability to climate change scenarios.

Peatlands are important sinks and stores of terrestrial carbon, but their future role in the global climate system under climate change is uncertain. Palaeoecological and experimental climate manipulation studies are commonly used to address these uncertainties, although their results often contradict each other. Furthermore, carbon accumulation rates estimated from both methods frequently fail to converge.We examine the effects of warming and episodic drought on carbon cycling from a long-term experimental site in an ombrotrophic peatland in Wales, simulating expected changes in temperature and drought frequency for the next c.70 years. We compare carbon accumulation rates modelled from the 10-year experiment (2010-2020) with those derived from a peat core covering the past c. 1500 years. We partition components of the annual carbon budget for each experimental treatment and compare them with core-derived carbon accumulation rates.Significant differences in carbon accumulation occurred between experimental treatments, resulting from cumulative non-significant changes in decay rates and productivity, driven by differences in air temperature and water table depth. We identify a positive time-lagged relationship between carbon accumulation and reconstructed temperature anomalies in the long-term carbon accumulation record. Changes in carbon accumulation also correspond to vegetation changes. We suggest that palaeoecological studies should not consider changes in plant productivity to be the sole determinant controlling carbon accumulation rates and should acknowledge the role of changing decay rates following plant succession upon long-term carbon accumulation. Carbon accumulation rates estimated from both methods may converge, but often differ due to unquantifiable losses such as by reduced productivity, decay, or anthropogenic disturbances like fire. We conclude that both methods are useful for discerning future peatland responses to climate change; however, core derived rates should be interpreted with consideration of all the contemporary mechanisms governing carbon accumulation. Based on these findings, we posit that the carbon sink function of existing peatlands will be weakened by increased warming and drought.

We test whether vegetation community composition from a 10-year climate manipulation experiment on a Welsh peat bog resembles vegetation communities during periods of climate change inferred from a peat core. Experimentally warmed and combined warmed and droughted treatments drove significant increases in ericaceous shrubs but Sphagnum was unaffected. Similarly, Calluna vulgaris seeds increase during inferred warmer periods in the palaeoecological record. Experimental short-term episodic drought (four 4-week drought treatments) did not affect vegetation. Plant community composition has undergone several abrupt changes throughout the past c. 1500 years, often in response to human disturbance. Only slight changes occurred during the Medieval Climate Anomaly (c. 950-1250 Common Era [CH) in vegetation and hydrology, while abrupt changes occurred during the Little Ice Age (c. 1300-1850 CE) when water tables were highest, suggesting that these shifts were driven by changes in water table, modulated by climate. A period of water table drawdown c. 1800, synchronous with historical records of increased drainage, corresponds with the development of the present-day vegetation community. Modern analogues for fossil material, characterized by abundant Rhynchospora alba and Sphagnum pulchrum, are more common after this event. Vegetation changes due to climate inferred from the palaeo record differ from those observed in the experiments, possibly relating to differences in the importance of drivers of vegetation change over varying timescales. Whereas temperature is frequently identified as the dominant driver of plant community change in experiments, sustained changes in water table appear to be more important in the long-term record. We find evidence that recent climate change and other anthropogenic stressors (e.g. drainage, heavy metal and nitrogen pollution) may promote the development of novel plant communities without analogues in the fossil record. These communities may be poorer at sequestering carbon and may respond differently to future climate change.

Data for study measuring the effects of warming and drought upon greenhouse gas fluxes and annual carbon budgets from a long term field experiment on a raised peat bog in Wales, compared with long term carbon accumulation rates inferred from a peat core from the same site (Cors Fochno, Wales). Contents: 1 Cors Fochno measured gas fluxes from 2010 - 20202 Cors Fochno pore-water DOC concentrations from 2017 - 2020 3 Carbon content, bulk peat density and basal dates for LORCA calculation4 210Pb, 14C and other chronohorizon data for core BO175 Age-depth model and carbon accumulation rates for core BO176 Annual modelled gas fluxes and carbon budgets7 Tephra geochemical data from core BO178 Time series modelled 6 hourly gas fluxes and measured environmental data (averaged across treatments)9 Dupont Hydrological Index calculation sheet for core BO17

Large areas of naturally open peatland in western Europe were drained and planted with non-native conifers in the twentieth century. Efforts arc currently underway to restore many of these sites. Ultimately, forest-to-bog restoration aims to bring back functional peatlands that can sequester carbon but there is a lack of empirical evidence for whether current approaches are effective. Using a chronosequence design, we compared the annual gaseous carbon balance of two forest-to-bog restoration areas with an open area not subject to afforestation. A closed chamber method was used to determine gas fluxes (Net Ecosystem Respiration, Gross Primary Productivity, Net Ecosystem Exchange (NEE) and methane (CH4)) over a twelve-month period for locations spanning the range of peatland microtopography and vegetation communities. Relationships between gas fluxes, vegetation/ cover and environmental factors were analysed and regression models used to estimate annual CO2 and CH4 budgets. During the study period, NEE estimates (total gaseous C expressed as CO2-eq) showed a net sink for the unafforested (-102 g C M-2 yr(-1)) and oldest ( -131 g C M-2 yr(-1)) restoration area (17 years post-restoration 'RES 17 YRS'), whilst the youngest restoration area (6 years post-restoration 'RES 6YRS'), was a net source (35 g C m(-2) yr (-1)). We observed significantly higher CH4 emissions from restoration areas dominated by Eriophorum angustifolium compared with other peatland vegetation types. Sampling points with higher cover of Sphagnum were found to be most effective for C sequestration. Overall, vegetation composition/cover was observed to be an important factor determining C emissions from forest-to-bog restoration areas. These results suggest that restoration is effective in returning the carbon sink function of peatlands damaged by commercial forestry and - depending on restoration techniques - timescales of >10 years may be required. (C) 2019 Elsevier B.V. All rights reserved.

The effects of 21st century climate change are projected to be most severe in the northern hemisphere, where the majority of peatlands are located. Peatlands represent important long-term terrestrial stores of carbon (C), containing an estimated c.600-1055GT C, despite covering only 3% of total land area globally. In addition, pristine peatlands act as net sinks of atmospheric CO2, imparting a negative feedback mechanism cooling global climate, whilst simultaneously acting as sources of CO2 and CH4. Peatlands remain net sinks of C as long as the rate of carbon sequestration exceeds that of decomposition. Projected changes in temperature, precipitation and other environmental variables threaten to disrupt this precarious balance, however, and the future direction of carbon feedback mechanisms are poorly understood, due to the complex nature of the peatland carbon cycle. Two methods are used in order to help understand future the carbon dynamics of peat bogs under climate change. These are experimental studies, which measure greenhouse gas fluxes under manipulated climatic and environmental conditions (warmer, drier), and palaeoecological studies, which examine the effects of past climate change upon carbon sequestration throughout the peat profile. However, both methods fundamentally contradict each other. Palaeoecological studies suggest that carbon accumulation increases during warming periods, whereas warming experiments observe greater carbon loss with increased temperature. The aim of this project is to link contemporary experimental and palaeoecological approaches to explain this discrepancy. This will be achieved by comparing greenhouse gas fluxes between plots which have been subjected to 10 years of passive warming and drought simulation at an experimental climate manipulation site on Cors Fochno, Ceredigion, Wales. Long term rates of carbon accumulation will be compared with net ecosystem contemporary carbon budgets from each plot. Surface samples from each plot will be analysed by a range of palaeoenvironmental proxies to test how well the climate manipulations are represented by each proxy. Finally, a high-resolution multi-proxy palaeoenvironmental reconstruction spanning the past 1000 years will be compared with reconstructions derived from short-cores from each plot covering the duration of the experiment from each treatment, to see how faithfully climate manipulation mirrors real periods of climate change. Understanding the future role of peatlands in future carbon sequestration and storage is of vital importance for modelling future climate change, in terms of both quantifying the potential ecosystem services peatlands may offer in mitigating the effects of climate change, as well as enhancing the predictive capabilities of global climate models. Currently, the uncertainty associated with peatland carbon cycling is such that peatlands are rarely included in global climate models.

In north-west Europe, large areas of open peatland have been drained and planted with spatially homogenous stands of non-native conifers. The detrimental impact of afforestation on peatland carbon and biodiversity have led to large-scale attempts to restore these landscapes back to their open, tree-less form. The responses of dominant microbial consumers testate amoebae to peatland forest-to-bog restoration are largely unexplored. We studied changes in testate amoebae with forest-to-bog restoration in the largest expanse of blanket bog in the UK and compared testate amoeba communities in relatively undisturbed open bog with forested and forest-to-bog restoration sites. Forested areas contained testate amoeba communities which were functionally different from open bog, characterised by a lack of mixotrophic taxa known to contribute to primary production. Seventeen years after restoration management, the microbial communities in the forest-to-bog sites remained more similar to forested areas than to the open bog community. Our results suggest that afforestation has reduced the trophic level of testate amoeba communities, which are only beginning to recover post-restoration in the wettest areas where Sphagnum has re-colonized. This study also highlights the need to consider a wide-range of reference sites to encompass the natural variability within ombrotrophic blanket bog. We conclude that testate amoebae have the potential to act as functionally-significant bio-indicators in peatlands undergoing forest-to bog restoration.

Climate change may cause increasing tree cover in boreal peatlands, and the impacts of this encroachment will be noted first at forested-to-open bog ecotones. We investigate key metrics of ecosystem function in five such ecotones at a peatland complex in Western Siberia. Stratigraphic analysis of three cores from one of these transects shows that the ecotone has been dynamic over time with evidence for recent expansion of forested peatland. We observed that the two alternative states for northern boreal peatlands (forested/open) clearly support distinct plant and microbial communities. These in turn drive and respond to a number of feedback mechanisms. This has led to steep ecological gradients across the ecotones. Tree cover was associated with lower water tables and pH, along with higher bulk density, aquatic carbon concentrations, and electrical conductivity. We propose that the conditions found in the forested peatland of Western Siberia make the carbon sink more vulnerable to warmer and drier conditions.

Climate change is likely to cause increased tree recruitment on open peatlands but we currently have little idea what consequences this vegetation change may have below-ground. Here we use transects across forested to open bog ecotones at three Russian peatland complexes to assess potential changes in the most abundant group of peatland protists – the testate amoebae. We show that the testate amoeba communities of forested and open bog are markedly different with a very abrupt boundary at, or near, the vegetation ecotone. Changes along our transects suggest that tree encroachment may reduce the trophic level of testate amoeba communities and reduce the contribution of mixotrophic testate amoebae to primary production. Our study strongly suggests that increased tree recruitment on open peatlands will have important consequences for both microbial biodiversity and microbially-mediated ecosystem processes.

This study seeks to investigate the role of Calluna vulgaris canopy height in the CO2 balance of ombrotrophic peatlands to address what implications this relationship may have for management of these peatlands for maximal carbon storage. This study uses a monthly dataset of CO2 flux and associated environmental variables gathered from three localities in the South Pennines and the Peak District National Park of northern England between 2007 and 2010, covering a range of C. vulgaris canopy heights. It was found that both gross fluxes of CO2 (ecosystem respiration and photosynthesis) were modelled best by models incorporating a dependence on canopy height. Ecosystem respiration was positively correlated and photosynthesis was negatively correlated to canopy height. It was found that as canopy height increases, the amount of photosynthesis per unit respiration decreased and thus that net ecosystem exchange became more positive. Despite the relationship between the gross fluxes and canopy height, models of net ecosystem exchange suggested that there was no canopy height at which blanket peat dominated by C. vulgaris would be a net annual sink of CO2. This was due to the relatively deep water tables at the sites which served to enhance ecosystem respiration. Looking at the dataset as a whole, for a 10 cm increase in canopy height there was a median increase of 0.829 +/- 0.583 g CO2 m(2) d(-1) in net CO2 flux, with considerable seasonal variation. Managers interested in minimising CO2 losses from blanket peat should note that C. vulgaris on blanket peat in the areas studied is predicted to be a net source of CO2 to the atmosphere for all canopy heights. As such, vegetation management away from C. vulgaris dominance is recommended to improve the functioning of these bogs. If vegetation management away from heather on climatically marginal blanket peat is infeasible then managers should avoid taller canopies, where day time photosynthesis is almost always less than day time respiration. (C) 2014 Elsevier B.V. All rights reserved.

Peatlands are among the largest long-term soil carbon stores on the globe, but their degradation can lead to significant carbon losses. Therefore, restoration of peatlands has received considerable attention but the impact of revegetation upon critical water quality parameters has not been assessed. In this paper we consider a 5-year study of three restored sites in comparison to both an unrestored, bare peat control and to a vegetated control that did not require restoration. The soil porewater dissolved organic carbon concentration (DOC) was measured (6 replicates) for each restoration treatment and each control. The soil water measurements were made in the context of measuring the depth to water table; soil water pH and conductivity; and DOC concentration in surface runoff for the same restored and control treatment. The study showed that the average soil porewater DOC concentration on the restored sites rose significantly over the 5 year study representing a 34% increase relative to the vegetated control and an 11% increase relative to the unrestored, bare control. Soil pore water concentrations were not significantly different from surface runoff DOC concentrations, and therefore restoration as conducted by this study would have contributed to water quality deterioration in the catchment. However, had water table restoration been conducted alongside revegetation then a significant decline in DOC concentrations could have been realised. (C) 2014 Elsevier B.V. All rights reserved.

This study aimed to measure the effects of ecological restoration on blanket peat water table depths and CO 2 fluxes. The flux of CO 2 and water table depths were measured on eight sites for 5 years. Results suggest that sites with revegetation alongside slope stabilisation have the highest rates of photosynthesis and are the largest net (daylight hours) sinks of CO 2 . Bare sites are the largest net sources of CO 2 and have the deepest water table depths. Sites with gully wall stabilisation are between 5 and 8 times more likely to be net CO 2 sinks than the bare sites. Revegetation without gully flow blocking using plastic dams does not have a large effect on water table depths in and around the gullies investigated whereas a blocked gully has water table depths comparable to a naturally revegetating gully. A 10 cm lowering in water table depth decreases the probability of observing a net CO 2 sink, on a given site, by up to 30 %. The most important conclusion of this research was that restoration interventions are effective at increasing the likelihood of net CO 2 sink behaviour and raising water tables on degraded, climatically marginal blanket bog.

This study considers the relative performance of six different models to predict soil respiration from upland peat. Predicting soil respiration is important for global carbon budgets and gap filling measured data from eddy covariance and closed chamber measurements. Further to models previously published new models are presented using two sub-soil zones and season. Models are tested using data from the Bleaklow plateau, southern Pennines, UK. Presented literature models include ANOVA using logged environmental data, the Arrhenius equation, modified versions of the Arrhenius equation to include soil respiration activation energy and water table depth. New models are proposed including the introduction of two soil zones in the peat profile, and season. The first new model proposes a zone of high CO2 productivity related to increased soil microbial CO2 production due to the supply of labile carbon from plant root exudates and root respiration. The second zone is a deeper zone where CO2 production is lower with less labile carbon. A final model allows the zone of high CO2 production to become dormant during winter months when plants will senesce and will vary depending upon vegetation type within a fixed location. The final model accounted for, on average, 31.9% of variance in net ecosystem respiration within 11 different restoration sites whilst, using the same data set, the best fitting literature equation only accounted for 18.7% of the total variance. Our results demonstrate that soil respiration models can be improved by explicitly accounting for seasonality and the vertically stratified nature of soil processes. These improved models provide an enhanced basis for calculating the peatland carbon budgets which are essential in understanding the role of peatlands in the global C cycle.

ABSTRACT UK peatlands are affected by severe gully erosion with consequent impacts on ecosystem services from these areas. Incision into the peat can damage the vegetation and hydrology and lead to increases in carbon loss and sediment transfer downstream. Gullies represent then a conduit for and a hotspot of carbon loss but the relatively high water tables of gullies have meant that they have been identified as areas with a high restoration potential because of easily restored peat‐forming conditions. This study uses a series of gully sites, subject to different restoration interventions, to investigate differences in carbon pathways (DOC, CO 2 ) and hydrology between restoration strategies and gully position. The results show that the position within the gully (interfluve, gully side, or gully floor) does not significantly affect water quality but that it plays a significant role in CO 2 exchange. Gully floors are areas of high photosynthesis and ecosystem respiration, though net ecosystem exchange is not significantly different across the gully. While gully position plays a role in the cycling of some carbon species, this study highlights the importance of vegetation as a key control on carbon cycling. Copyright © 2012 John Wiley & Sons, Ltd.

ABSTRACTPeatlands are among the largest long‐term soil carbon stores, but their degradation can lead to significant carbon losses. This study considers the carbon budget of peat‐covered sites after restoration, following degradation by past wildfires. The study measured the carbon budget of eight sites: four restored‐revegetated sites, two unrestored bare soil control sites, and two intact vegetated controls over two years (2006–2008). The study considered the following flux pathways: dissolved organic carbon (DOC); particulate organic carbon (POC); dissolved carbon dioxide (CO2); primary productivity; net ecosystem respiration, and methane (CH4). The study shows that unrestored, bare peat sites can have significant carbon losses as high as 522 ± 3 tonnes C/km2/yr. Most sites showed improved carbon budgets (decreased source and/or increased sink of carbon) after restoration; this improvement was mainly in the form of a reduction in the size of the net carbon source, but for one restored site the measured carbon budget after four years of restoration was greater than observed for vegetated controls. The carbon sequestration benefit of peatland restoration would range between 122 and 833 tonnes C/km2/yr. Copyright © 2011 John Wiley & Sons, Ltd.

This study measures the complete carbon budget of a drained peat-covered catchment. It includes dissolved organic carbon (DOC), particulate organic carbon (POC), dissolved CO(2), primary pro-ductivity, soil respiration of carbon dioxide (CO(2)) and methane (CH(4)) in contrast to other studies which have focused on only some of the possible carbon uptake and release pathways; values for rainfall inputs were taken from a nearby catchment. The study is based on data collected over 2 yr for two drain catchments within one site and the main findings are:1. The catchments were a net source of all forms of carbon at between +63.8 and +106.8 Mg C/km2/yr;2. There was a net loss of between +9.3 and +40.7 Mg C/km2/yr in terms of exchange of carbon with the atmosphere;3. The small size of the study catchments seems to have resulted in higher values of exported DOC than recorded elsewhere and the highly disturbed drainage of the site may have given rise to losses in net ecosystem exchange (NEE).If the fate of the peatland carbon store is to be understood, then it is important that all carbon uptake and release pathways are considered and not just components of the carbon cycle.

We compared output from 3 dynamic process-based models (DMs: ECOSSE, MILLENNIA and the Durham Carbon Model) and 9 bioclimatic envelope models (BCEMs; including BBOG ensemble and PEATSTASH) ranging from simple threshold to semi-process-based models. Model simulations were run at 4 British peatland sites using historical climate data and climate projections under a medium (A1B) emissions scenario from the 11-RCM (regional climate model) ensemble underpinning UKCP09. The models showed that blanket peatlands are vulnerable to projected climate change; however, predictions varied between models as well as between sites. All BCEMs predicted a shift from presence to absence of a climate associated with blanket peat, where the sites with the lowest total annual precipitation were closest to the presence/absence threshold. DMs showed a more variable response. ECOSSE predicted a decline in net C sink and shift to net C source by the end of this century. The Durham Carbon Model predicted a smaller decline in the net C sink strength, but no shift to net C source. MILLENNIA predicted a slight overall increase in the net C sink. In contrast to the BCEM projections, the DMs predicted that the sites with coolest temperatures and greatest total annual precipitation showed the largest change in carbon sinks. In this model inter-comparison, the greatest variation in model output in response to climate change projections was not between the BCEMs and DMs but between the DMs themselves, because of different approaches to modelling soil organic matter pools and decomposition amongst other processes. The difference in the sign of the response has major implications for future climate feedbacks, climate policy and peatland management. Enhanced data collection, in particular monitoring peatland response to current change, would significantly improve model development and projections of future change.

The retention of peatland carbon (C) and the ability to continue to draw down and store C from the atmosphere is not only important for the UK terrestrial carbon inventory, but also for a range of ecosystem services, the landscape value and the ecology and hydrology of similar to 15% of the land area of the UK. Here we review the current state of knowledge on the C balance of UK peatlands using several studies which highlight not only the importance of making good flux measurements, but also the spatial and temporal variability of different flux terms that characterise a landscape affected by a range of natural and anthropogenic processes and threats. Our data emphasise the importance of measuring (or accurately estimating) all components of the peatland C budget. We highlight the role of the aquatic pathway and suggest that fluxes are higher than previously thought. We also compare the contemporary C balance of several UK peatlands with historical rates of C accumulation measured using peat cores, thus providing a long-term context for present-day measurements and their natural year-on-year variability. Contemporary measurements from 2 sites suggest that current accumulation rates (-56 to -72 g C m(-2) yr(-1)) are at the lower end of those seen over the last 150 yr in peat cores (-35 to -209 g C m(-2) yr(-1)). Finally, we highlight significant current gaps in knowledge and identify where levels of uncertainty are high, as well as emphasise the research challenges that need to be addressed if we are to improve the measurement and prediction of change in the peatland C balance over future decades.