pH controls over anaerobic carbon mineralization,the efficiency of methane production,and methanogenic pathways in peatlands across an ombrotrophic–minerotrophic gradient

Methane (CH₄) production varies greatly among different types of peatlands along an ombrotrophic–minerotrophic hydrogeomorphic gradient. pH is thought to be a dominant control over observed differences in CH₄ production across sites, and previous pH manipulation experiments have verified the inhibitory effect of low pH on CH₄ production. In this experiment, we asked (i) if the major effect of low pH is direct inhibition of one or both pathways of methanogenesis and/or inhibition of ‘upstream’ fermentation that provides substrates for methanogens, and (ii) to what extent is pH sufficient to explain differences in CH₄ production relative to other factors that co-vary across the gradient. To address these questions, we adjusted the pH of peat slurries from 6 peatlands to 4 levels (3.5, 4.5, 5.5, and 6.5) that reflected their range of native pH, maintained these pH levels over a 43-day anaerobic laboratory incubation, and measured a suite of responses within the anaerobic carbon cycle. Higher pH caused a significant increase in CO₂ production in all sites. Regardless of site, time, and pH level, the reduction of inorganic electron acceptors contributed to <12% of total CO₂ production. Higher pH caused acetate pooling by Day 7, but this effect was greater in the more ombrotrophic sites and lasted throughout the incubation, whereas acetate was almost completely consumed as a substrate for acetoclastic methanogenesis by Day 43 in the minerotrophic sites. Higher pH also enhanced CH₄ production and this process was up to 436% more sensitive to changes in pH than CO₂ production. However, across all sites and pH levels, CH₄ production accounted for <25% of the total gaseous C production. Fermentation appeared to be the main pathway for anaerobic C mineralization. Our results indicate that low pH inhibits CH₄ production through direct inhibition of both methanogenesis pathways and indirectly through its effects on fermentation, but the direct effects are stronger. The inability of acetoclastic methanogenesis to fully compensate for acetate pooling in ombrotrophic peats at higher pH suggests that CH₄ production is inhibited by some factor(s) in addition to pH in these sites. We examine a variety of other potential inhibitory mechanisms and postulate that humic substances may provide an important inhibitory effect over CH₄ production in ombrotrophic peatlands.     

Patterns of amphibian diversity in Brazilian Amazonia: conservation implications

A literature survey was conducted to determine the amphibian diversity and distribution in Brazilian Amazonia. Patterns of endemisms and similarity of fauna between localities were also addressed. Twenty-eight inventories were found for the region, the majority localized in areas with easier access by road or river. A minimum of 163 amphibian species was recorded for Brazilian Amazonia. Although many species are endemic to the Amazonian lowlands as an entity, the patterns of species uniqueness among sites suggested low endemic distribution within the lowlands of the Amazon Basin. The mean similarity between localities varied from low to intermediate (mean=0.40), indicating that the Brazilian Amazonia is characterized by distinctive assemblages of amphibians throughout its extension. Localities further apart had lower similarity. No threatened species were recorded. These results contribute to determine priority areas for new inventories and establishment of conservation units. We suggest that areas next to the Amazon deforestation frontier should be prioritized for new studies due to the high rate of alteration and potential loss of species. Additionally, studies on amphibian population dynamics are few in Brazilian Amazonia and more of them should be emphasized to help to draw a better picture of the status of amphibians in this region.     

Long-term effects of deer browsing and trampling on the vegetation of peatlands

Overabundance of wild ungulates, especially exotic species, is a major threat to several ecosystems worldwide. While the response of forest vegetation to high density of herbivores has been well studied, far less is known about peatland vegetation. In this paper, we assessed the long term impact of white-tailed deer (Odocoileus virginianus) on plant communities of ombrotrophic (bog) and minerotrophic (fen) peatlands in eastern North America. Vegetation of five peatlands that have experienced high deer densities for at least 75 years was compared with that of five peatlands situated at proximity but on deer-free islands. We investigated deer impacts on plant species composition and cover, shrub height and cloudberry (Rubus chamaemorus) fruit/flower production and morphology. In bogs, white-tailed deer had no long-term impact on plant species assemblages, but reduced lichen cover and increased sedges and grasses cover as well as the surface area of bare peat. On the other hand, the floristic composition of fens differed significantly between sites where deer were present or absent. Plant diversity was greater in undisturbed fens than in disturbed fens, especially for shrubs, sedges and liverworts. No detrimental effects of browsing on shrub height were observed. Conversely, deer browsing seemed to have deleterious impacts on cloudberry fruit/flower production as well as on the number of leaves per individual. Overall, our results suggest that white-tailed deer had some important impacts on the vegetation of peatlands that could be harmful for the long-term conservation of peatland plant diversity.     

Mass loss and nutrient release during litter decay in peatland: The role of microbial adaptability to litter chemistry

In peatlands the reduced decomposition rate of plant litter is the fundamental mechanism making these peat-accumulating ecosystems effective carbon sinks. A better knowledge of litter decomposition and nutrient cycling is thus crucial to improve our predictions of the effects of anthropogenic perturbation on the capacity of peatlands to continue to behave as carbon sinks. We investigated patterns of plant litter decomposition and nutrient release along a minerotrophic-ombrotrophic gradient in a bog on the south-eastern Alps of Italy. We determined mass loss as well as P, N, K, and C release of seven vascular plant species and four moss species after 1 year in both native and transplanted habitats. Hence, differences in litter decay were supposed to reflect the degree of adaptability of microbial communities to litter quality. Polyphenols/nutrient and C/nutrient quotients appeared as the main parameters accounting for decomposition rates of Sphagnum litter. In particular, litter of minerotrophic Sphagnum species decomposed always faster than litter of ombrotrophic Sphagnum species, both in native and transplanted habitats. Decomposition rates of vascular plant litter in native habitats were always higher than the corresponding mass loss rates of Sphagnum litter. Minerotrophic forbs showed the fastest decomposition both in native and transplanted habitats in accordance with low C/P and C/N litter quotients. On the other hand, C/P quotient seems to play a primary role also in controlling decomposition of graminoids. Decomposition of deciduous and evergreen shrubs was negatively related to their high lignin content. Nitrogen release from Sphagnum litter was primarily controlled by C/N quotient, so that minerotrophic Sphagnum litter released more N than ombrotrophic Sphagnum litter. Overall, we observed slower N release from litter of ombrotrophic vascular plant species compared to minerotrophic vascular plant species. No single chemical parameter could predict the variability associated with different functional groups. The release of K was very high compared to all the other nutrients and rather similar between ombrotrophic and minerotrophic litter types. In Sphagnum litter, a higher C/P quotient was associated with a slower P mineralisation, whereas a faster P release from vascular plant litter seems primarily associated with lower C/P and polyphenols/P quotients.     

Geochemistry and geochemical differentiation on major elements in selected peat bog profiles (south-east of Poland)

Abstract

The geochemical differentiation of major elements in various peat bog profiles from Bieszczady Mountains Region (south-east of Poland) was compared to its botanical origin. Peat cores were taken from ombrotrophic, mesotrophic, and oligotrophic peatlands, which were developed in the stream valley of the River San. Twenty-four various peat samples were analysed for peat genus, degree of peat decomposition, ash content, total nitrogen, and total carbon content of hydrolytic matter as well as content of major elements: Na, K, Mg, Ca. The results show that the botanical composition of peat deposits is no reliable indication of their trophic status. The common feature of investigated Holocene peatlands is their valley localisation on the flood terrace. The specific character of local geommorpho8ogicml and hydrological condition caused that the bottom layer of all investigated bog profiles was made of wood peats (Piceaeti, Pineti, Alneti, and Saliceti peat). The geochemical investigations of stratigraphical profiles confirm that the presented peat bogs showed specific morphological separateness comparing to other raised bogs situated in mountains or lowlands     

Peatland Interstitial Water Chemistry in Relation to that of Surface Pools along a Peatland Mineral Gradient

The elemental (including silica (Si), calcium (Ca), magnesium (Mg), manganese (Mn) and iron (Fe)) and nutrient composition of peatland surface pools and concentrations of Ca, Mg, Mn, and Fein peat interstitial waters and surface peat concentrations of oxides of Mn and Fe were determined for 15 peatlands sampled along a mineral gradient. Surface pool concentrations of Si wereca. ten fold less in surface pools of mineral-poor peatlands thanin the mineral rich, supporting the use of this element as an indicator of minerotrophic influence in peatlands. Principle component analysis of surface pool water chemistry parametersdifferentiated mineral-poor and moderately-poor peatlands frommineral-rich peatlands based on the concentrations of Ca, Mgand alkalinity of pools. Several lines of evidence indicated that peatland interstitial waters were important contributors to peatland alkalinity and included; (1) maximum interstitial water concentrations of Ca and Mg correlating with overlying surface pool alkalinity, (2) a negative correlation between interstitial water Ca:Mg ratios and surface pool concentrationsof Si and (3) Ca:Mg ratios of moderately-poor to mineral-poorpeatland interstitial waters approaching the Ca:Mg ratio of rainwater rather than those of bedrock. Interstitial water concentrations of dissolved Mn and Fe correlated with amountsof reducible Fe and Mn (oxides of Fe and Mn) recovered from thepeat/water interface indicating that groundwater inputs areimportant sources of these two elements to fens. As a consequence, for peatlands that are not truly ombrotrophic,groundwater inputs of Mn and Fe may interfere with interpretingpeat metal profiles thought to be due to anthropogenic inputs alone.     

Long‐term drainage for forestry inhibits extracellular phenol oxidase activity in Finnish boreal mire peat

Drainage for forestry has been amongst the most extensive of land management practices applied to northern latitude peatlands, particularly in northern Europe. Extracellular phenol oxidases play an important role in the carbon cycle of soils. This study investigated the effects of long‐term (45 years) drainage for forestry upon surface peat extracellular phenol oxidase activity, soluble phenolic concentrations and pH at ombrotrophic bog, oligotrophic fen and mesotrophic fen sites at a Finnish mire complex. Phenol oxidase activity was reduced by drainage at all three sites. Phenol oxidase activity was positively correlated with peat pH across all sites irrespective of drainage treatment, suggesting that pH is a major factor influencing peat phenol oxidase activity at the mire complex. Peat pH became more acidic with drainage at the fen sites, and it is likely that this contributed to the suppression of peat phenol oxidase activity. The reduction of peat phenol oxidase activity with drainage was accompanied by increased concentrations of water‐soluble phenolics at all three sites, and the potential contribution of this to changes in peat carbon stocks following drainage is discussed.     

The 1949 Atlas of French peat deposits,a starting point for a national inventory of peatlands

Fifty per cent of European peatlands are in a damaged state. While intact peatlands are natural carbon sinks, degraded sites release important amounts of greenhouse gases into the atmosphere, contributing to global warming. Restoration of the hydrological functionality of peatlands has proved to be an efficient tool to avoid these emissions. In France, Tuffnell & Bignon's ministerial report (2019) emphasized the need for peatlands ‘integration into the National Low Carbon Strategy, targeting carbon neutrality by 2050. However, current knowledge regarding French peatlands’ distribution and carbon stocks is insufficient and does not allow decision makers and managers to prioritize areas for restoration. The most complete database to date is the 1949 Atlas, an inventory of exploitable peat deposits that was conducted during WWII for peat exploitation as fuel. Until its digitalization, the latter database was archived and never used in a scientific study. It provides detailed information about peatland surfaces, peat thicknesses and carbon contents at that time. We estimated peat carbon stocks from French peatlands to be 111 Mt C in 1949 for 63,290 ha identified as peaty sites, the equivalent of 3% of the organic carbon contained in the upper 30 centimetres of French soils. 34% of this stock was held in Lower Normandy (37.7 Mt C) and 12% in the Picardy's region (13.0 Mt C), in large lowland peatlands. However, not all peatlands were prospected in the 1949 inventory and the characteristics of the prospected peatlands may have changed with anthropic disturbances of the last decades, such as draining or climate change. These first results highlight the need for a recent inventory of French peatlands and carbon stocks based on local data aggregation. Data from the 1949 Atlas could help constituting this new inventory but should be validated before being used to describe the present.     

Soil organic matter characterization of temperate peatland soil with FTIR‐spectroscopy: effects of mire type and drainage intensity

Peatlands are an important component of the global carbon cycle because they comprise huge amounts of terrestrial carbon (C). Different conditions during peat formation and secondary peat decomposition affect the quantity and composition of soil organic matter (SOM) in peats. There are few comparative studies on the chemical composition of SOM in temperate peatland soil. This study investigates compositional changes of SOM functional groups in peats and corresponding peat‐forming plants by Fourier transform infrared (FTIR) spectroscopy. Three plant samples and 29 peat samples were taken from seven temperate peatland sites with different genesis and land‐use intensity. Site‐specific differences, such as genesis of the peat, were found to be reflected in the FTIR spectra. In general, there was more variation in FTIR spectra in samples from fens than in those from bogs and peat‐forming plants. The samples from fens have a smaller C–H absorption band than those from bogs and plants, which reflects greater biochemical activity in the minerotrophic than ombrotrophic environments. In addition to peat genesis, drainage and secondary peat decomposition also affect SOM composition substantially. The larger amounts of aliphatic compounds in undrained peats could be explained by selective preservation caused by anaerobic conditions. With increasing drainage of the sites, there was a decrease in the C–H absorption that was accompanied by a relative increase in C=O absorption. These changes in absorption intensities reflect the enhanced aerobic decomposition and mineralization that accompanies drainage and land‐use intensity. However, the ‘degree of peat decomposition’, a diagnostic tool used in the field, is not reflected by OM composition determined by FTIR spectroscopy. Our results contribute to further understanding of changes in SOM composition during peat formation and processes of secondary decomposition caused by drainage.     

Natural and anthropogenic enrichments of As,Cu, Pb,Sb, and Zn in ombrotrophic versus minerotrophic peat bog profiles,Jura Mountains,Switzerland

Peat cores were taken from two contrasting Sphagnum bogs in the Jura Mountains of Switzerland. At Etang de la Gruyere (EGr), 6.5 m of peat has accumulated during the past 10,000 years. In the first 100 cm of this profile there are several distinct peaks in ash content, but the values are well within the range for typical ombrotrophic Sphagnum bogs. There is also considerable variation in the concentrations of major and trace lithogenic metals (Al, Ti, Sc, Ca, Mg, Rb, and Sr), but most of this is simply a reflection of the natural variations in the amount of mineral matter in the peats. The Ca/Mg molar ratios in the peats at EGr are comparable to or lower than the average rainwater composition in this area, showing that this section of the peat core is ombrotrophic (i.e. rainwater-fed). In other words, the inorganic constituents in the surface peats at EGr were supplied exclusively by atmospheric deposition. This peat core, therefore, is suitable for studying the historical record of atmospheric metal deposition. Arsenic, Cu, Pb, Sb, and Zn are all more abundant in surface and near surface peat layers compared to deeper parts of the profile. Enrichment factors (EFs) for the profile were calculated conservatively by normalizing the metal/Sc ratios of individual peat samples to the average of the five lowest metal/Sc ratios in this part of the core (69–84 cm); these are tentatively assumed to represent pre-Industrial background values. The maximum EFs are approximately 5 times for Cu, 15 times for As, and 30 to 50 times for Pb, Sb, and Zn. At La Tourbière des Genevez (TGe), 1.5 m of peat represents 4,800 years of peat formation. At this site, the ash contents are higher and increase progressively with depth to values which are characteristic of minerotrophic fen peats. The concentration profiles of Al, Ti, Sc, Ca, Mg, Rb, Sr show the same general trend. The Ca/Mg molar ratios of these peats are generally twice the rainwater average, showing that this bog is essentially minerotrophic (ie groundwater-fed). Thus, the inorganic cccstituents in these peats were provided by both atmospheric and hydrospheric processes. Despite this, the Cu, Pb, Sb, and Zn concentrations are generally very similar to those at EGr, especially in the uppermost part of the profile, indicating that recent atmospheric inputs also dominate the supply of these metals to this bog. However, the minimum Pb and Sb concentrations in this profile are approximately five times higher than the corresponding values at EGr. The minerotrophic profile at TGT, therefore, could not by itself be used to calculate rates of atmospheric Pb and Sb deposition because it is impossible to distinguish between atmospheric and hydrospheric metal inputs. At TGe, As concentrations increase continuously with depth, reaching concentrations in the deeper, older peats which are more than 50 times higher than the ‘background’ As values at EGr. At this site the natural supply of As by mineral soil water completely masks the recent, elevated inputs contributed by atmospheric deposition. Thus, the peat core from TGe is also unsuitable for studying atmospheric As deposition.     

Carbon stocks in Scottish peatlands

Various estimates have suggested that the peatlands of Scotland are a significant deposit of fixed carbon. However, these have been based upon rather imprecise estimates of peat depth. Using previously unused archived data, we have mapped peat depth across the country and then used these values to obtain an improved value of the total carbon stock within peatlands, as well as indicating their spatial distribution. We included peat deposits that occur in combination with other soils in soil map units other than 'blanket' or 'basin' peat. We obtained an area-weighted mean peat depth of 2.0 m, which is slightly shallower than previous estimates. Using values of bulk density and % carbon from the Scottish soils database, the total peatland carbon stock came to 1620 Mt, which represents 56% of the total carbon in all Scottish soils.     

Decomposition activity of peat soils in geogenous mires in Sasakami, central Japan

Decomposition rates of peat and cellulose, and oxygen consumption rates were studied in three minerotrophic peat mires in Sasakami, central Japan. These mires had differences in topography, pedology and hydrology. Two dominant vegetation types in each mire, a Sphagnum palustre–S. cuspidatum community and a Rhynchospora fauriei community, were selected as the decomposition study sites. The objective of this study was to examine how the environmental and vegetational differences in mires correlate with the activity of decomposition. Decomposition rates of peat and the rates of cellulolysis were studied in the field for 6 months. Oxygen consumption rates were measured in the field using a closed chamber equipped with an oxygen electrode. In situ peat decomposition rates showed significant differences among the three mires, whereas in situ cellulolysis rates showed significant differences between communities. Peat mass loss rates positively correlated with the nitrogen and carbon concentration of the peat. Cellulolysis rates positively correlated with the range of water table fluctuation. Oxygen consumption rates showed significant negative correlation with the averaged and minimum water table depth, and positive correlation with the range of water table fluctuation. There was a significant positive correlation between cellulolysis rates and oxygen consumption rates. These are useful parameters for evaluating how the decomposition activity in soil depends on the vegetation types and water conditions.     

Highly Organic Soils as “Witnesses” of Anthropogenic Pb, Cu, Zn, and 137Cs Inputs During Centuries

Highly organic soils, and in particular ombrotrophic bogs, have been often used to reconstruct climate changes and heavy metal contaminations. Ombrotrophic peat bogs, in fact, are domed peatlands in which the surface layers are hydrologically isolated from the influence of local groundwaters and surface waters, and are supplied only by atmospheric depositions. In the present work, the attention of Authors has been focused on Pb, Cu, and Zn, coming mainly from anthropogenic activities, and ¹³⁷Cs, released mostly during the Chernobyl disaster. Practically, an undisturbed peat profile was cored in 2005 from a Swiss ombrotrophic bog and analysed using energy-dispersive miniprobe multielement analyzer X-ray fluorescence and Low Background γ-ray spectrometry in order to investigate and quantify the impact of human activities (e.g., industry, traffic, combustion of fossil fuels, “environmental disasters”) in causing Pb, Cu, Zn, and ¹³⁷Cs contaminations during the centuries. Obtained data show that highly organic soils in general, and ombrotrophic bogs in particular, reflect the anthropogenic inputs in heavy metal and radionuclide contaminations. In fact, these environments allowed to follow the depositional history of Pb, Cu, and Zn, both underlining a general increasing of their production since the Industrial Revolution, and remarking past single impacting events such as the introduction of leaded gasoline and of particular agricultural practices. Further, although ¹³⁷Cs showed a main peak corresponding to the Chernobyl disaster, confirming the role of bogs as archive of human activity, data revealed a certain mobility of this radionuclide along the profile. Thus, highly organic soils can be considered as both “witness” of the impact of human activity during centuries and indicator of the health of our planet.     

Ti and Pb Concentrations in Rainwater-Fed Bogs in Europe as Indicators of Past Anthropogenic Activities

Chemical and physical analyses of dated ombrotrophic peat cores from 8 European regions were undertaken to determine the effect of forest clearances, farming, mining and smelting on the composition of atmospheric aerosols. Elemental concentrations in peat were determined using XRF and the mean concentrations of Ti and Pb in peat as well as Pb enrichment factors (Pb EFs) were calculated for each region and for different time periods (Roman Times, Dark Ages, Middle Ages, modern times). The results show that the concentration of Ti, Pb and the calculated Pb EFs closely follow changes in land use history extending back thousands of years. Concentrations of Ti, for example, reflect changing soil dust inputs in response to forest clearing and agriculture. Lead emissions are characterized by considerable continental-scale variations: elevated concentrations and EFs during the Roman Period at most sites, very high concentrations and EFs in the Harz Mountains during the Medieval period, and elevated to high concentrations and EFs during modern times at all sites. The findings indicate that peat cores from ombrotrophic bogs are useful not only for quantifying temporal changes in metal emissions, but also for identifying spatial variations on scales ranging from regional to global.     

Regional significance of peatlands for avifaunal diversity in southern Québec

Altough peatlands in southern Québec are facing increasing pressure, neither specific nor substantial protection measures have been implemented, partly due to a lack of information on this ecosystem. We determined the contribution of peatlands to bird regional diversity by measuring the difference between peatland and associated regional avifaunas. We sampled 112 peatlands located along the Saint Lawrence River during one breeding season. We used data on regional nesting bird assemblages from the Québec breeding bird atlas. Peatland bird species contrasted increasingly with regional avifauna from north to south or from undisturbed to managed landscapes. Of the 17 bird species found significantly more often in peatlands than in surroundings, some preferred peatlands in the whole study area and others preferred peatlands only in particular regions. Peatland avifaunas within regions were more similar to each other than to their regional avifauna, and differences between regions probably reflected changes in peatland physiognomy. We conclude that peatlands contribute to enrich local and regional avian diversity, particularly in the lowlands of the Saint Lawrence River, where industrial pressure on peatlands is highest.     

Acid Mine Drainage Treatment Assisted by Lignite-Derived Humic Substances

Rewetting of agriculturally used peatlands has been proposed as a measure to stop soil subsidence, conserve peat and rehabilitate ecosystem functioning. Unintended consequences might involve nutrient release and changes in the greenhouse gas (GHG) balance towards CH₄-dominated emission. To investigate the risks and benefits of rewetting, we subjected soil columns from drained peat- and clay-covered peatlands to different water level treatments: permanently low, permanently inundated and fluctuating (first inundated, then drained). Surface water and soil pore water chemistry, soil-extractable nutrients and greenhouse gas fluxes were measured throughout the experiment. Permanent inundation released large amounts of nutrients into pore water, especially phosphorus (up to 11.7 mg P-PO₄ l^?1) and ammonium (4.8 mg N-NH₄ l^?1). Phosphorus release was larger in peat than in clay soil, presumably due to the larger pool of iron-bound phosphorus in peat. Furthermore, substantial amounts of phosphorus and potassium were exported from the soil matrix to the surface water, risking the pollution of local species-rich (semi-)aquatic ecosystems. Rewetting of both clay and peat soil reduced CO₂ emissions. CH₄ emissions increased, but, in contrast to the expectations, the fluxes were relatively low. Calculations showed that rewetting reduced net cumulative GHG emissions expressed as CO₂ equivalents.     

增温与干旱双重变化对若尔盖泥炭CH4排放的影响

若尔盖泥炭地经历了长期人为排水,未来又面临着强烈的变暖干旱,会对泥炭地CH₄排放产生复杂影响。在若尔盖选取了近自然和长期人为排水两种泥炭地类型,采集1 m深泥炭柱,采用室内环境控制试验,设定不同的氧气、水分和温度条件,探索这两种典型泥炭地的泥炭CH₄排放对增温与干旱双重变化的响应差异。结果表明:(1)由于水位降低和泥炭有机物质量下降,长期排水泥炭地的中下层泥炭(20—80 cm)CH₄累积排放量显著低于近自然泥炭地。(2)两种泥炭地的表层和深层泥炭CH₄排放都对升温不敏感,而中下层泥炭的CH₄累积排放量从5℃到15℃显著增加。(3)模拟增温10℃同时干旱水位降低20 cm条件下,中层泥炭受到了温度、水分和氧气变化的叠加影响,CH₄排放变化最剧烈。(4)最终整个1 m深泥炭近自然泥炭地高温低水位的CH₄总排放量为(204.29±15.13)μg/gC,比其低温高水位显著升高66.43 μg/gC(约48%); 排水泥炭地高温低水位的CH₄总排放量为(75.64±9.41)μg/gC,比其低温高水位升高11.95 μg/gC(约19%)。综上,升温干旱气候会对若尔盖泥炭地的有机碳稳定性造成破坏性影响,会集中导致中层泥炭CH₄排放的剧烈变化,可能最终使本区域CH₄排放量显著提高。     

FTIR spectroscopy can be used as a screening tool for organic matter quality in regenerating cutover peatlands

Vegetational changes during the restoration of cutover peatlands leave a legacy in terms of the organic matter quality of the newly formed peat. Current efforts to restore peatlands at a large scale therefore require low cost and high throughput techniques to monitor the evolution of organic matter. In this study, we assessed the merits of using Fourier transform infrared (FTIR) spectra to predict the organic matter composition in peat samples at various stages of peatland regeneration from five European countries. Using predictive partial least squares (PLS) analyses, we were able to reconstruct peat C:N ratio and carbohydrate signatures with reasonable accuracy, but not the micromorphological composition of vegetation remains. Despite utilising different size fractions, both carbohydrate (<200 μm fraction) and FTIR (bulk soil) analyses report on the composition of plant cell wall constituents in the peat and therefore essentially reveal the composition of the parent vegetational material. The accuracy of the FTIR-based PLS models for C:N ratios and carbohydrate signatures was adequate to allow for their use as initial screening tools in the evaluation of the present and future organic matter composition of peat during monitoring of restoration efforts.     

Evaluation of phosphorus mobilization potential in rewetted fens by an improved sequential chemical extraction procedure

After rewetting of peatlands, phosphorus (P) pore‐water concentrations were up to three orders of magnitude greater than under pristine conditions. It was hypothesized that different mobilization processes such as ion‐exchange reactions, biotic/abiotic redox reactions, acidification and ongoing anaerobic decomposition of particulate organic matter by hydrolytic cleavage and fermentation might be responsible. To identify P pools in peat samples of varying degrees of decomposition, we modified and improved a sequential chemical extraction method that allowed conclusions on potential mobilization mechanisms in rewetted peatlands. The results indicated that the earlier drainage of rewetted fens strongly increased the P mobilization potential in the upper decomposed peat layers. Accordingly, the amount of P bound to redox‐sensitive (bicarbonate/dithionite soluble) compounds (BD‐P) was, on average, one order of magnitude greater in decomposed peat of rewetted fens (5.4–14.3 μmol P g^?1 dry matter or DM) than in underlying less‐decomposed peat layers (0.2–1.9 μmol P g^?1 DM) or slightly decomposed peat derived from pristine fens (0.4–2.0 μmol P g^?1 DM). The BD‐P fraction found in the upper very decomposed peat layers appears to be most important for P mobilization in rewetted fens and accounted for 85% of the variability of P mobilization rates. Despite uncertainties regarding P diagenetic processes in peat, as well as the development of microbial decomposition processes, in the long‐term, high pore‐water P concentrations can be expected in rewetted fens for decades to come.     

Estimating the carbon stock of a blanket peat region using a peat depth inference model

At the global scale peatlands are an important soil organic carbon (SOC) pool. They sequester, store and emit carbon dioxide and methane and have a large carbon content per unit area. In Ireland, peatlands cover between 17% and 20% of the land area and contain a significant, but poorly quantified amount of SOC. Peatlands may function as a persistent sink for atmospheric CO₂. In Ireland the detailed information that is required to calculate the peatland SOC pool, such as peat depth, area and carbon density, is inconsistent in quality and coverage. The objective of this research was to develop an improved method for estimating the depth of blanket peat from elevation, slope and disturbance data to allow more accurate estimations of the SOC pool for blanket peatlands. The model was formulated to predict peat depth at a resolution of 100 ha (1 km²). The model correctly captured the trend and accounted for 58 to 63% of the observed variation in peat depth in the Wicklow Mountains on the east coast of Ireland. Given that the surface of a blanket peatland masks unknown undulations at the mineral/peat interface this was a successful outcome. Using the peat depth model, it was estimated that blanket peatland in the Wicklow Mountains contained 2.30 Mt of carbon. This compares to the previously published values ranging from 0.45 Mt C to 2.18 Mt C.