The responses of peatland invertebrates to land use changes and associated effects of peatland degradation are not well known, particularly for diverse and species-rich taxa such as moths. We ...investigated broad patterns of distribution in moth communities during the restoration of formerly afforested blanket bog, as well as their degree of habitat affinity (tyrphophilia). Thus, we examined the response of moth communities to peatland management across a restoration chronosequence and used information about species traits to explain the species’ responses to restoration (trait syndromes). A clear shift towards open habitat moth species and away from specialist forest species took place following tree felling, and the moth communities of restoration treatments resembled the bog community within a few years following onset of restoration. Interestingly, species traditionally considered tyrphobionts (bog specialists) were not restricted to core bog habitats. Trait syndromes were identified for each treatment, highlighting the importance of phylogenetic, phenological and ecological performance traits linked mainly to species microhabitat selection, resource use and dispersal capability. The restoration of afforested blanket bog opens up the habitat for the recolonisation of bog-inhabiting moth species, mediated by species functional traits. However, a better understanding of moth functional traits, especially linked to moth ecology (including habitat preferences), is needed to aid understanding of the relationship between restoration trajectory, species traits and blanket bog habitat.
Peat drainage, a common land-use practice in Europe, has been associated with habitat degradation and increased particulate and dissolved carbon release. In the UK, peatland drain blockage has been ...encouraged in recent years as a management practice to preserve peatland habitats and to reduce fluvial carbon loss and municipal water discoloration. Drain blockage has, however, been found to increase drain-water dissolved organic carbon (DOC) concentrations and coloration in the short term. In order to investigate the contribution of changes in extracellular phenol oxidase activity to the increase in water coloration following peatland drain blockage, cores collected from a riparian peatland in North Wales were incubated under impeded drainage conditions. Impeded drainage resulted in the stimulation of peat extracellular phenol oxidase activity and heightened soluble phenolic concentrations, suggesting that changes in extracellular phenol oxidase activity may be a key driver of increases in DOC and water coloration following peatland drain blockage. An increase in peat pH with impeded drainage was also observed that may have contributed to the heightened soluble phenolic concentrations - directly (through effects on solubility) and/or indirectly as a driver of the elevated extracellular phenol oxidase activity.
Yamulki and co-authors address in their recent publication the important issue of net emissions of greenhouse gases (GHGs) from peatlands where land use conversion has taken place. In their case, ...they studied conversion to forestry versus peatland restoration after a first rotation of plantation forestry. They monitored soil-derived fluxes of carbon dioxide (CO2 ), methane (CH4 ) and nitrous oxide (N2 O) using opaque chamber measurements on planted and unplanted control treatments (with or without drainage), and an unplanted plot within a restored (felled) block on former lowland raised bog. They propose that their measurements of greenhouse gas (GHG) emissions at these sites suggest that the total net GHG emissions, in 100 yr carbon dioxide equivalents, of the restored peat bog would be higher than that of the peat bog with trees. We believe there are a number of issues with the measurement, calculation and comparison of these greenhouse budgets that may invalidate this conclusion.
Summary
The influence of soil structure in controlling leaching of Escherichia coli O157:H7 through soil was investigated under controlled conditions using both intact and repacked soil cores. ...Leaching rates of E. coli O157:H7 decreased with increasing dry bulk density and were significantly increased by the presence of earthworm (Lumbricus terrestris) burrows in repacked cores. For intact cores, the percentage of E. coli O157:H7 that leached through replicate cores within 72 h varied from 0.01% to 24%. In contrast, the dry bulk densities of intact cores varied only slightly and were not significantly correlated with leaching. Differences in the numbers of E. coli O157:H7 cells in the leachates were not related to variability in the flow volumes, which were relatively constant as a result of the experimental design, but were strongly correlated with the variations in concentrations of E. coli O157:H7 in the leachates. Relatively small variations in the internal structure of soil cores can therefore significantly affect the pathway that cells can take through soil. Factors such as compaction and the occurrence of pores providing preferential flow are prime determinants in the degree of leaching of E. coli O157:H7 through soil.
Abstract Peat makes up approximately a quarter of Scotland's soil by area. Healthy, undisturbed, peatland habitats are critical to providing resilient biodiversity and habitat support, water ...management, and carbon sequestration. A high and stable water table is a prerequisite to maintain carbon sink function; any drainage turns this major terrestrial carbon store into a source that feeds back further to global climate change. Drainage and erosion features are crucial indicators of peatland condition and are key for estimating national greenhouse gas emissions. Previous work on mapping peat depth and condition in Scotland has provided maps with reasonable accuracy at 100‐m resolution, allowing land managers and policymakers to both plan and manage these soils and to work towards identifying priority peat sites for restoration. However, the spatial variability of the surface condition is much finer than this scale, limiting the ability to inventory greenhouse gas emissions or develop site‐specific restoration and management plans. This work involves an updated set of mapping using high‐resolution (25 cm) aerial imagery, which provides the ability to identify and segment individual drainage channels and erosion features. Combining this imagery with a classical deep learning‐based segmentation model enables high spatial resolution, national scale mapping to be carried out allowing for a deeper understanding of Scotland's peatland resource and which will enable various future analyses using these data.
Understanding the climatic and biological factors that regulate soil carbon dioxide (CO2) efflux is crucial in peatlands because they contain a large proportion of terrestrial carbon (C). We ...predicted that rainfall reduction would increase soil CO2 efflux, and that cessation of below-ground allocation of recent plant assimilate would reduce soil CO2 efflux. These predictions were tested in the field using rainfall shelters that allowed a maximum of 40 % of rainfall onto 2 × 2 m plots by diverting rainwater from the shelter roofs with guttering, and by girdling stems of the dominant plant, Calluna vulgaris, for two years. We also used 13CO2-pulse labelling of intact monoliths at ambient CO2 concentrations to trace recent assimilate from plant shoots to roots, bulk soil, leachate, dissolved organic carbon (DOC) and soil CO2 efflux . Soil CO2 efflux in the sheltered plots increased in Year 1 but not in Year 2, and we found a positive relationship between soil CO2 efflux and water table depth. Our data indicate that lowering the water table below a critical threshold (15–20 cm) affects soil CO2 efflux. Girdling of C. vulgaris shoots resulted in no measurable reduction in soil CO2 efflux, while only ~3 % of 13C fixed by shoots was recovered in soil CO2 efflux and DOC in the 20 days after labelling. Our findings show that below-ground allocation of recent assimilate from C. vulgaris plants > 6 years old has little impact on soil CO2 efflux.
Peatlands contain a significant fraction of global soil carbon, but how these reservoirs will respond to the changing climate is still relatively unknown. A global picture of the variations in peat ...organic matter chemistry will aid our ability to gauge peatland soil response to climate. The goal of this research is to test the hypotheses that (a) peat carbohydrate content, an indicator of soil organic matter reactivity, will increase with latitude and decrease with mean annual temperatures, (b) while peat aromatic content, an indicator of recalcitrance, will vary inversely, and (c) elevation will have a similar effect to latitude. We used Fourier Transform Infrared Spectroscopy to examine variations in the organic matter functional groups of 1034 peat samples collected from 10 to 20, 30–40, and 60–70 cm depths at 165 individual sites across a latitudinal gradient of 79°N–65°S and from elevations of 0–4,773 m. Carbohydrate contents of high latitude peat were significantly greater than peat originating near the equator, while aromatic content showed the opposite trend. For peat from similar latitudes but different elevations, the carbohydrate content was greater and aromatic content was lower at higher elevations. Higher carbohydrate content at higher latitudes indicates a greater potential for mineralization, whereas the chemical composition of low latitude peat is consistent with their apparent relative stability in the face of warmer temperatures. The combination of low carbohydrates and high aromatics at warmer locations near the equator suggests the mineralization of high latitude peat until reaching recalcitrance under a new temperature regime.
Plain Language Summary
Peatlands are a large global soil carbon reservoir, containing a quantity of carbon that is equivalent to about half or more of the carbon dioxide in the atmosphere. What will be their fate on a warming planet? Across a latitudinal gradient from 79°N to 65°S, we measured the fraction of the peat made up of carbohydrates, which are easily decomposed, and of aromatics, which are less easily decomposed. We found that peat from high latitudes and high elevations had greater carbohydrate content, while aromatic content showed the opposite trend. Larger carbohydrate content in organic matter indicates greater decomposability, while greater aromatic content indicates lower decomposability. We suggest that this latitude/elevation difference that we observed predicts how high‐latitude and high‐elevation peats may change under warmer conditions. Our work indicates that while a large portion of the carbohydrate fraction in these peats could be lost upon warming, releasing greenhouse gases, a residual fraction will survive and become more aromatic‐rich, making the remainder more resistant to rapid decomposition.
Key Points
Peatland soil organic matter stability can be evaluated through the relative abundances of carbohydrate and aromatic content in peat
Peat at higher latitudes and elevations has larger carbohydrate and smaller aromatic content relative lower latitudes and elevations
Our results foreshadow a transition of organic matter from higher latitude peatlands to a more recalcitrant form in response to warming
Globally, major efforts are being made to restore peatlands to maximise their resilience to anthropogenic climate change, which puts continuous pressure on peatland ecosystems and modifies the ...geography of the environmental envelope that underpins peatland functioning. A probable effect of climate change is reduction in the waterlogged conditions that are key to peatland formation and continued accumulation of carbon (C) in peat. C sequestration in peatlands arises from a delicate imbalance between primary production and decomposition, and microbial processes are potentially pivotal in regulating feedbacks between environmental change and the peatland C cycle. Increased soil temperature, caused by climate warming or disturbance of the natural vegetation cover and drainage, may result in reductions of long-term C storage via changes in microbial community composition and metabolic rates. Moreover, changes in water table depth alter the redox state and hence have broad consequences for microbial functions, including effects on fungal and bacterial communities especially methanogens and methanotrophs. This article is a perspective review of the effects of climate change and ecosystem restoration on peatland microbial communities and the implications for C sequestration and climate regulation. It is authored by peatland scientists, microbial ecologists, land managers and non-governmental organisations who were attendees at a series of three workshops held at The University of Manchester (UK) in 2019–2020. Our review suggests that the increase in methane flux sometimes observed when water tables are restored is predicated on the availability of labile carbon from vegetation and the absence of alternative terminal electron acceptors. Peatland microbial communities respond relatively rapidly to shifts in vegetation induced by climate change and subsequent changes in the quantity and quality of below-ground C substrate inputs. Other consequences of climate change that affect peatland microbial communities and C cycling include alterations in snow cover and permafrost thaw. In the face of rapid climate change, restoration of a resilient microbiome is essential to sustaining the climate regulation functions of peatland systems. Technological developments enabling faster characterisation of microbial communities and functions support progress towards this goal, which will require a strongly interdisciplinary approach.
Soils are the largest pool of carbon (C) in terrestrial ecosystems with labile C being particularly vulnerable to loss. In this study we incubated a range of soils in both the short- (minutes) and ...long-term (months) to assess the loss of labile soil C by measuring the isotopic signature of soil respired CO2 (∂13CO2). Strong temporal trends in ∂13CO2 values were observed following soil disturbance: ∂13CO2 rapidly changed from a range of −22.5 to −23.9‰ to −25.8 to −27.5‰ during short-term incubations and reverted back to the initial values in long-term incubations. The shifts in ∂13CO2 over the course of soil incubations were consistent with changes in labile C substrate utilization following the disturbance of sampling the soil. An independent experimental approach which immobilised labile soil C onto allophane and included chemical extractions as a measure of extractable C in soils also confirmed this interpretation. Collectively, these results indicate that the isotopic analysis of respired CO2 can be a powerful technique which enables us to probe mechanisms and examine the consequences of disturbance on the labile component of soil C.
•Soils were incubated in the short- (minutes) and long-term (months).•Respired ∂13CO2 were measured in soil incubations.•Rapid changes in ∂13CO2 after soil disturbance were due to release of labile C.•∂13CO2 reverted back in the long-term due to consumption of labile C pools.•Experimental manipulation of labile soil C was evident in ∂13CO2.
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