Small-scale spatial variability of hydro-physical properties of natural and degraded peat soils

Wang, Miaorun; Liu, Haojie; Lennartz, Bernd

doi:10.1016/j.geoderma.2021.115123

Cited by 34 publications

(28 citation statements)

References 88 publications

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“…2b), and thus we did not combine these but instead used only the data from Liu and Lennartz (2019) since this was a global synthesis as opposed to the O'Connor et al (2020) data which were from a single region. The data in Liu and Lennartz (2019) also agreed better with other data, such as Wang et al (2021), and the original values used for organic soils in JULES, originally given in Dankers et al (2011) (also shown in Fig. 2).…”

Section: Coupling Between Properties and C Concentrationsupporting

confidence: 81%

“…The maximum bulk density of 210 kg m −3 corresponds well to the threshold bulk density for peat functioning in, e.g. Wang et al (2021). We relate the bulk density of the organic material to the carbon content by assuming that f c = 0.56 or, in other words, that 56 % of the organic matter is carbon, which was also based on the 95th percentile of the percentage of carbon in the peat core dataset from Gallego-Sala et al ( 2018) (see Sect.…”

Section: Chadburnsupporting

confidence: 53%

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A new approach to simulate peat accumulation, degradation and stability in a global land surface scheme (JULES vn5.8_accumulate_soil) for northern and temperate peatlands

et al. 2022

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Abstract. Peatlands have often been neglected in Earth system models (ESMs). Where they are included, they are usually represented via a separate, prescribed grid cell fraction that is given the physical characteristics of a peat (highly organic) soil. However, in reality soils vary on a spectrum between purely mineral soil (no organic material) and purely organic soil, typically with an organic layer of variable thickness overlying mineral soil below. They are also dynamic, with organic layer thickness and its properties changing over time. Neither the spectrum of soil types nor their dynamic nature can be captured by current ESMs. Here we present a new version of an ESM land surface scheme (Joint UK Land Environment Simulator, JULES) where soil organic matter accumulation – and thus peatland formation, degradation and stability – is integrated in the vertically resolved soil carbon scheme. We also introduce the capacity to track soil carbon age as a function of depth in JULES and compare this to measured peat age–depth profiles. The new scheme is tested and evaluated at northern and temperate sites. This scheme simulates dynamic feedbacks between the soil organic material and its thermal and hydraulic characteristics. We show that draining the peatlands can lead to significant carbon loss, soil compaction and changes in peat properties. However, negative feedbacks can lead to the potential for peatlands to rewet themselves following drainage. These ecohydrological feedbacks can also lead to peatlands maintaining themselves in climates where peat formation would not otherwise initiate in the model, i.e. displaying some degree of resilience. The new model produces similar results to the original model for mineral soils and realistic profiles of soil organic carbon for peatlands. We evaluate the model against typical peat profiles based on 216 northern and temperate sites from a global dataset of peat cores. The root-mean-squared error (RMSE) in the soil carbon profile is reduced by 35 %–80 % in the best-performing JULES-Peat simulations compared with the standard JULES configuration. The RMSE in these JULES-Peat simulations is 7.7–16.7 kg C m−3 depending on climate zone, which is considerably smaller than the soil carbon itself (around 30–60 kg C m−3). The RMSE at mineral soil sites is also reduced in JULES-Peat compared with the original JULES configuration (reduced by ∼ 30 %–50 %). Thus, JULES-Peat can be used as a complete scheme that simulates both organic and mineral soils. It does not require any additional input data and introduces minimal additional variables to the model. This provides a new approach for improving the simulation of organic and peatland soils and associated carbon-cycle feedbacks in ESMs.

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Section: Coupling Between Properties and C Concentrationsupporting

confidence: 81%

Section: Chadburnsupporting

confidence: 53%

A new approach to simulate peat accumulation, degradation and stability in a global land surface scheme (JULES vn5.8_accumulate_soil) for northern and temperate peatlands

et al. 2022

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“…Rewetting peatlands decreases diffusion rates by increasing soil water content. However, long term drainage decreases total porosity and thus the relative abundance of large pores that promote pore connectivity (Wang Mairoun et al, 2021). Diffusion is likely the main pathway of CO 2 and N 2 O emission to the atmosphere in drained peatlands.…”

Section: Gas Transportmentioning

confidence: 99%

Back to the Future: Restoring Northern Drained Forested Peatlands for Climate Change Mitigation

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Belyazid

Manzoni

2022

Front. Environ. Sci.

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Draining peatlands for forestry in the northern hemisphere turns their soils from carbon sinks to substantial sources of greenhouse gases (GHGs). To reverse this trend, rewetting has been proposed as a climate change mitigation strategy. We performed a literature review to assess the empirical evidence supporting the hypothesis that rewetting drained forested peatlands can turn them back into carbon sinks. We also used causal loop diagrams (CLDs) to synthesize the current knowledge of how water table management affects GHG emissions in organic soils. We found an increasing number of studies from the last decade comparing GHG emissions from rewetted, previously forested peatlands, with forested or pristine peatlands. However, comparative field studies usually report relatively short time series following rewetting experiments (e.g., 3 years of measurements and around 10 years after rewetting). Empirical evidence shows that rewetting leads to lower GHG emissions from soils. However, reports of carbon sinks in rewetted systems are scarce in the reviewed literature. Moreover, CH4 emissions in rewetted peatlands are commonly reported to be higher than in pristine peatlands. Long-term water table changes associated with rewetting lead to a cascade of effects in different processes regulating GHG emissions. The water table level affects litterfall quantity and quality by altering the plant community; it also affects organic matter breakdown rates, carbon and nitrogen mineralization pathways and rates, as well as gas transport mechanisms. Finally, we conceptualized three phases of restoration following the rewetting of previously drained and forested peatlands, we described the time dependent responses of soil, vegetation and GHG emissions to rewetting, concluding that while short-term gains in the GHG balance can be minimal, the long-term potential of restoring drained peatlands through rewetting remains promising.

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“…Researchers in Germany, that is, Wang et al (2021), reported peat hydrophysical properties of undrained peatland and two fen peatlands drained in 16th and 13th centuries and under agricultural usage, as grasslands, since second half of 20th century. They reported that α…”

Section: Comparison Of Irish Peat Hydrophysical Properties Versus Lit...mentioning

confidence: 99%

Quantifying moss moisture stresses in undrained, afforested and rewetted peatlands located in Republic of Ireland using laboratory measurements and computer modelling

et al. 2021

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This study utilized site-specific peat hydrophysical properties (inverse of air-entry pressure, α; pore size distribution index, n; saturated hydraulic conductivity, Ks; and pore tortuosity, L) as inputs into the HYDRUS 1-D computer model for quantifying moss moisture stresses on Irish peatlands. The site-specific peat hydrophysical properties computed using pedotransfer functions obtained from laboratory measured bulk density (BD) and % organic matter (OM). The peat samples obtained from undrained sites (Scohaboy, Pollagoona and Lough Ghe), three afforested sites (S18, S28 and S44) and rewetted sites (Scohaboy and Pollagoona). The moss moisture stresses quantified using a known ecohydrological threshold of À100 cm. The sitespecific peat hydrophysical properties, four initial WTDs (3, 8, 20 and 30 cm) and two distinct precipitation regimes (single and consecutive 4 years having severely dry [SD], extremely dry [ED], near normal [NN], very wet [VW] and extremely wet[EW] periods) were inputs into HYDRUS 1-D model. The modelling results showed that none of the peatland sites ever reached À100 cm threshold in single year simulations at all initial WTDs. However, in the consecutive 4-year simulations, Scohaboy, Pollagoona and Lough Ghe undrained, S28 afforested and Pollagoona rewetted sites first reached À100 cm threshold on 516, 508, 624, 1329 and 517 day, respectively.In the consecutive 4-year simulations, undrained Scohaboy, Pollagoona, Lough Ghe, S28 afforested and Pollagoona rewetted reached À100 cm threshold in ED and SD years. We concluded that moss recolonization is likely to be successfully on peatlands having minimal to no À100 cm threshold days.ecohydrological threshold of À100 cm to À200 cm, HYDRUS 1-D and peat hydrophysical properties, raised peatland, blanket peatland and afforested peatlands, Sphagnum mosses | INTRODUCTIONPeatlands store $33% of the world's soil carbon and are long-term sinks of atmospheric carbon (Gorham, 1991;Leifeld & Menichetti, 2018;Schimel, 1995). The Sphagnum mosses, key peat forming species in Northern peatlands, lack root structure for water transport, but instead depend upon capillary rise to the capitula for supporting photosynthesis (Clymo, 1973;Hayward & Clymo, 1982;Weston et al., 2015). During periods of drought and deeper water table depths (WTDs), the moss moisture stresses often reach

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Small-scale spatial variability of hydro-physical properties of natural and degraded peat soils

Cited by 34 publications

References 88 publications

A new approach to simulate peat accumulation, degradation and stability in a global land surface scheme (JULES vn5.8_accumulate_soil) for northern and temperate peatlands

A new approach to simulate peat accumulation, degradation and stability in a global land surface scheme (JULES vn5.8_accumulate_soil) for northern and temperate peatlands

Back to the Future: Restoring Northern Drained Forested Peatlands for Climate Change Mitigation

Quantifying moss moisture stresses in undrained, afforested and rewetted peatlands located in Republic of Ireland using laboratory measurements and computer modelling

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