Hydrogeomorphic controls on soil carbon composition in two classes of subalpine wetlands

Daugherty, Ellen E.; McKee, Georgina A.; Bergstrom, Robert M.; Burton, Sarah D.; Pallud, Céline; Hubbard, Robert M.; Kelly, Eugene F.; Rhoades, Charles C.

doi:10.1007/s10533-019-00597-y

Cited by 18 publications

(16 citation statements)

References 74 publications

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“…It is possible to assess peat quality through basic peat properties such as C:N ratio, isotopes or degree of decomposition (Glatzel et al., 2004; Krüger et al., 2014; Reiche et al., 2010). Chemical composition of substrates can be determined via spectroscopy, for example using Fourier‐transform infrared (FTIR), visible to near‐infrared (Vis‐NIR), 13 C solid‐state nuclear magnetic resonance (NMR), and pyrolysis gas chromatography‐mass spectrometry (Py‐GC/MS) ( e.g ., Artz et al., 2008; Daugherty et al., 2019; Hoyos‐Santillan et al., 2016; Swails et al., 2018). Another approach is the identification of labile and more recalcitrant compounds by wet chemical fractionation of the soil.…”

Section: Introductionmentioning

confidence: 99%

“…Secondary reactions, chemical artefacts and losses might occur during wet chemical extraction procedures and therefore, compared with spectroscopy, the results only provide an estimation of chemical composition (Kögel‐Knabner, 1997; Schmidt et al., 2011). Even though there is a multitude of methods to determine substrate quality, previous studies have mainly focused on natural peatlands ( e.g ., Artz et al., 2008; Daugherty et al., 2019; Hermans et al., 2019; Hoyos‐Santillan et al., 2016; Tfaily et al., 2014). In comparison, studies on drained organic soils used for agriculture are rare (Heller et al., 2015; Leifeld et al., 2012; Negassa et al., 2019).…”

Section: Introductionmentioning

confidence: 99%

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Substrate quality of drained organic soils—Implications for carbon dioxide fluxes

Säurich

Tiemeyer²,

Dettmann

et al. 2021

J. Plant Nutr. Soil Sci.

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Background Peatlands only cover a minor fraction of the global terrestrial surface, but due to drainage, they are major contributors to carbon dioxide (CO2) emissions from soils. Previous studies have shown that hydrological conditions, nutrient availability and anthropogenic disturbance play an important role in the mineralisation of organic matter. Furthermore, microbial turnover depends on peat quality, which is determined by its botanical origin and degree of transformation under natural conditions. Aims The objective of this study was to shed light on the interdependence between mineralisation rates, secondary transformation of peat and chemical composition by examining the differences between bog and fen peat and between strongly degraded topsoil and well‐preserved subsoil. Methods Bog and fen peat from ten different peatlands under grassland use in Germany were analysed for their chemical composition using standard 13C nuclear magnetic resonance (NMR) spectroscopy and wet chemical extractions for fibre analysis. The radiocarbon age was determined as well. The results were combined with CO2 fluxes from a previous incubation study. Results Topsoils had higher shares of proteins and lipids, and lower shares of carbohydrates and aromatics than subsoils. Bog peat subsoils were characterised by higher shares of carbohydrates and lower shares of aromatics than fen peat subsoils. Topsoils were more similar to each other in their chemical composition than the subsoils. Considering all samples, aromatics and phenolics were negatively correlated with CO2 fluxes. Measured CO2 fluxes from topsoils were significantly higher than from subsoils. However, no influences of chemical composition on CO2 fluxes were detected when examining topsoils and subsoils separately. Even though aromatics and phenolics showed positive relationships with radiocarbon age, differences in age alone were unable to explain the higher amounts of these compounds in the subsoil. Conclusions The results imply that chemical composition of topsoil peat is not the reason for higher mineralisation rates compared to subsoil peat, but rather a consequence of decomposition and transformation. Thus, peat mineralisation of drained organic soils under agriculture might not slow down over time due to gradually decreasing peat quality but could increase further.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Substrate quality of drained organic soils—Implications for carbon dioxide fluxes

Säurich

Tiemeyer²,

Dettmann

et al. 2021

J. Plant Nutr. Soil Sci.

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“…Dense willow clumps ( Salix planifolia ) differentiate larger openings (~2500 m 2 ) in sparse forests at upper elevations from forb‐dominated communities within closed‐canopy forests at lower elevations. Soils surrounding the springs are deep (>1 m), poorly drained Histic Cryoaquolls with surface peat layers (Alstatt & Miles, 1983; Daugherty et al, 2019). Organic layers average 20 cm deep but extend beyond 60 cm in some openings that are fed by multiple springs.…”

Section: Methodsmentioning

confidence: 99%

“…Emergent groundwater springs create wetland openings that vary in size and plant species composition and maintain their saturated soil conditions (Ruddy & Williams, 1991). The plant communities associated with the emerging springs are typical of central Rocky Mountain wetlands underlain by metamorphosed, crystalline bedrock (Carsey et al, 2003;LaPerriere Nelson et al, 2011 (Alstatt & Miles, 1983;Daugherty et al, 2019).…”

Section: Emergent Groundwater Springsmentioning

confidence: 99%

Sources of variability in springwater chemistry in Fool Creek, a high‐elevation catchment of the Rocky Mountains, Colorado, USA

Rhoades

Fegel

Covino

et al. 2021

Hydrological Processes

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Springs are the point of origin for most headwater streams and are important regulators of their chemical composition. We analysed solute concentrations of water emerging from 57 springs within the 3 km 2 Fool Creek catchment at the Fraser Experimental Forest and considered sources of spatial variation among them and their influence on the chemical composition of downstream water. On average, calcium and acid neutralizing capacity (bicarbonate-ANC) comprised 50 and 90% of the cation and anion charge respectively, in both spring and stream water. Variation in inorganic chemical composition among springs reflected distinct groundwater sources and catchment geology. Springs emerging through glacial deposits in the

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“…Clay content has historically been used as proxy for SOC stabilization with mineral surfaces in upland soils (Keiluweit et al 2018;Oades 1988) and has been assumed to also play a major role in wetland SOC sequestration (Daugherty et al 2019). However, clay content alone does not clarify mechanisms of SOC accumulation and stabilization, especially in seasonally saturated soils where C cycles are in uenced by numerous hydrologic and biogeochemical factors (e.g., LaCroix et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Physical protection in aggregates and organo-mineral associations contribute to carbon stabilization at the transition zone of seasonally saturated wetlands

Kottkamp

Jones

Palmer

et al. 2021

Preprint

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Wetlands store significant soil organic carbon (SOC) globally, yet this SOC is sensitive to climate and land use change. Seasonally saturated wetlands experience fluctuating hydrologic conditions that may promote the physicochemical mechanisms known to control SOC stabilization in upland soils; these wetlands are therefore likely to be important for SOC storage at the landscape-scale. We investigated the role of physicochemical mechanisms of SOC stabilization in five seasonally saturated wetlands to test the hypothesis that these mechanisms are present, particularly at the transition zone between wetland and upland where saturation in the upper soil profile is most variable. At each wetland, we monitored water level and collected soil samples at five points along a transect from frequently saturated basin edge to rarely saturated upland. We quantified physical protection of SOC in aggregates and organo-mineral associations in mineral horizons to 0.5 m depth. As expected, SOC decreased from basin edge to upland. In the basin edge and transition zone, the majority of SOC was physically protected in macroaggregates. By contrast, overall organo-mineral associations were low, with the highest Fe concentrations (5 mg Fe g− 1 soil) in the transition zone. While both stabilization mechanisms were present in the transition zone, physical protection is more likely to be a dominant mechanism of SOC stabilization in seasonally saturated wetlands. As future climate scenarios predict changes in wetland wet and dry cycles, understanding the mechanisms by which SOC is stabilized in wetland soils is critical for predicting the vulnerability of SOC to future change.

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Hydrogeomorphic controls on soil carbon composition in two classes of subalpine wetlands

Cited by 18 publications

References 74 publications

Substrate quality of drained organic soils—Implications for carbon dioxide fluxes

Substrate quality of drained organic soils—Implications for carbon dioxide fluxes

Sources of variability in springwater chemistry in Fool Creek, a high‐elevation catchment of the Rocky Mountains, Colorado, USA

Physical protection in aggregates and organo-mineral associations contribute to carbon stabilization at the transition zone of seasonally saturated wetlands

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