High potential for iron reduction in upland soils

Yang, Wendy H.; Liptzin, Daniel

doi:10.1890/14-2097.1

Cited by 37 publications

(37 citation statements)

References 39 publications

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“…Alluvium soil Fe concentrations were comparable to tropical forest soils where microbial Fe reduction is known to inhibit CH 4 production. Yang and Liptzin (2015) observed mean Fe concentrations of 23.6 mg Fe/g soil in forest soils where Teh et al (2008) had previously documented suppression of methanogenesis by microbial Fe reduction. Alluvium wetland Fe concentrations were similar (21.76 AE 5.88 mg Fe/g soil; n = 30), demonstrating that Fe concentrations were within the range where microbial Fe reduction inhibits methanogenesis.…”

Section: Discussionmentioning

confidence: 74%

“…Alluvium wetland Fe concentrations were similar (21.76 ± 5.88 mg Fe/g soil; n = 30), demonstrating that Fe concentrations were within the range where microbial Fe reduction inhibits methanogenesis. In contrast to upland humid tropical forests where most Fe is found in poorly crystalline form (Dubinsky et al., ; Hall & Silver, ; Yang & Liptzin, ), poorly crystalline Fe concentrations were roughly two orders of magnitude lower than the HCl‐extractable Fe pool across the wetland sites. Poorly crystalline Fe pools are readily reducible by soil microbes (Hall & Silver, ; Hyacinthe et al., ), and depletion of these pools suggests high activity by microbial Fe reducers in wetland soils (Weiss, Emerson, & Megonigal, ).…”

Section: Discussionmentioning

confidence: 79%

“…Alluvium wetland Fe concentrations were similar (21.76 AE 5.88 mg Fe/g soil; n = 30), demonstrating that Fe concentrations were within the range where microbial Fe reduction inhibits methanogenesis. In contrast to upland humid tropical forests where most Fe is found in poorly crystalline form (Dubinsky et al, 2010;Hall & Silver, 2015;Yang & Liptzin, 2015), poorly crystalline Fe concentrations were roughly two orders of magnitude lower than the F I G U R E 6 Annual CH 4 flux (F CH4 ) and greenhouse gas budgets (GHG) across the two recently restored peat and alluvium wetlands, as well as the mature wetland restored on peat soils. Annual GHG budget is computed from annual F CH4 and NEE budgets using the sustained global warming potential for CH 4 (Neubauer & Megonigal, 2015) HCl-extractable Fe pool across the wetland sites.…”

Section: Discussionmentioning

confidence: 95%

“…Alluvium soil Fe concentrations were comparable to tropical forest soils where microbial Fe reduction is known to inhibit CH 4 production. Yang and Liptzin () observed mean Fe concentrations of 23.6 mg Fe/g soil in forest soils where Teh et al. () had previously documented suppression of methanogenesis by microbial Fe reduction.…”

Section: Discussionmentioning

confidence: 98%

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Soil properties and sediment accretion modulate methane fluxes from restored wetlands

Chamberlain

Anthony

Silver

et al. 2018

Global Change Biology

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Wetlands are the largest source of methane (CH ) globally, yet our understanding of how process-level controls scale to ecosystem fluxes remains limited. It is particularly uncertain how variable soil properties influence ecosystem CH emissions on annual time scales. We measured ecosystem carbon dioxide (CO ) and CH fluxes by eddy covariance from two wetlands recently restored on peat and alluvium soils within the Sacramento-San Joaquin Delta of California. Annual CH fluxes from the alluvium wetland were significantly lower than the peat site for multiple years following restoration, but these differences were not explained by variation in dominant climate drivers or productivity across wetlands. Soil iron (Fe) concentrations were significantly higher in alluvium soils, and alluvium CH fluxes were decoupled from plant processes compared with the peat site, as expected when Fe reduction inhibits CH production in the rhizosphere. Soil carbon content and CO uptake rates did not vary across wetlands and, thus, could also be ruled out as drivers of initial CH flux differences. Differences in wetland CH fluxes across soil types were transient; alluvium wetland fluxes were similar to peat wetland fluxes 3 years after restoration. Changing alluvium CH emissions with time could not be explained by an empirical model based on dominant CH flux biophysical drivers, suggesting that other factors, not measured by our eddy covariance towers, were responsible for these changes. Recently accreted alluvium soils were less acidic and contained more reduced Fe compared with the pre-restoration parent soils, suggesting that CH emissions increased as conditions became more favorable to methanogenesis within wetland sediments. This study suggests that alluvium soil properties, likely Fe content, are capable of inhibiting ecosystem-scale wetland CH flux, but these effects appear to be transient without continued input of alluvium to wetland sediments.

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Section: Discussionmentioning

confidence: 74%

Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 98%

See 2 more Smart Citations

Soil properties and sediment accretion modulate methane fluxes from restored wetlands

Chamberlain

Anthony

Silver

et al. 2018

Global Change Biology

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“…In specific for these sites, however, it seems more likely that ammonium oxidation coupled to iron reduction (i.e., Feammox) or other forms of chemo‐denitrification play an important role in soils with high Fe content (Yang et al. , , Xi et al. ) and low pH (Heil et al.…”

Section: Discussionmentioning

confidence: 99%

Contrasting nitrogen fluxes in African tropical forests of the Congo Basin

Bauters

Verbeeck

Rütting

et al. 2019

Ecological Monographs

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The observation of high losses of bioavailable nitrogen (N) and N richness in tropical forests is paradoxical with an apparent lack of N input. Hence, the current concept asserts that biological nitrogen fixation (BNF) must be a major N input for tropical forests. However, well‐characterized N cycles are rare and geographically biased; organic N compounds are often neglected and soil gross N cycling is not well quantified. We conducted comprehensive N input and output measurements in four tropical forest types of the Congo Basin with contrasting biotic (mycorrhizal association) and abiotic (lowland–highland) environments. In 12 standardized setups, we monitored N deposition, throughfall, litterfall, leaching, and export during one hydrological year and completed this empirical N budget with nitrous oxide (N2O) flux measurement campaigns in both wet and dry season and in situ gross soil N transformations using 15N‐tracing and numerical modeling. We found that all forests showed a very tight soil N cycle, with gross mineralization to immobilization ratios (M/I) close to 1 and relatively low gross nitrification to mineralization ratios (N/M). This was in line with the observation of dissolved organic nitrogen (DON) dominating N losses for the most abundant, arbuscular mycorrhizal associated, lowland forest type, but in contrast with high losses of dissolved inorganic nitrogen (DIN) in all other forest types. Altogether, our observations show that different forest types in central Africa exhibit N fluxes of contrasting magnitudes and N‐species composition. In contrast to many Neotropical forests, our estimated N budgets of central African forests are imbalanced by a higher N input than output, with organic N contributing significantly to the input‐output balance. This suggests that important other losses that are unaccounted for (e.g., NOx and N2 as well as particulate N) might play a major role in the N cycle of mature African tropical forests.

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Drivers and patterns of iron redox cycling from surface to bedrock in a deep tropical forest soil: a new conceptual model

et al. 2016

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Iron (Fe) reduction and oxidation are important biogeochemical processes coupled to decomposition, nutrient cycling, and mineral weathering, but factors controlling their rates and spatial distribution with depth are poorly understood in terrestrial soils. In aquatic ecosystems, Fe reduction often occurs below a zone of oxic sediments. We tested an alternative conceptual model for Fe redox cycling in terrestrial soils using a deep humid tropical forest soil profile. We hypothesized that Fe reduction in anaerobic microsites scales with depth variation in labile C and Fe availability, as opposed to bulk oxygen (O2). We measured bulk O2 at multiple depths from 0.1 to 5 m quasi-continuously over 18 months and sampled soils from surface to bedrock (~7 m). Median O2 mixing ratios declined from 19.8 ± 1.2 % at 0.25 m to 16.1 ± 1.0 % at 1 m, but did not consistently decrease below 1 m, challenging a recent model of regolith development. Reduced Fe (Fe(II)) extractable in 0.5 M hydrochloric acid was greatest in 0-0.1 m soil and declined precipitously with depth, and did not correspond with visible gleying in B horizons. We observed similar depth trends in potential Fe reduction under anaerobic conditions. Depth trends in Fe(II) also closely mirrored short-term soil respiration and bulk soil C. Labile C stimulated Fe reduction at 0-0.1 m depth, whereas addition of short-range-ordered Fe oxides had no effect. Cultivable Fe-reducing bacterial abundance was four orders of magnitude greater in surface soil (0-0.1 m) than below 1 m. Although cultivable Fe oxidizing bacteria were typically also more abundant in surface soil, addition of labile C and nitrate stimulated Fe oxidizers in deep soil by two orders of magnitude under anaerobic conditions. This implies that infiltration of nitrate (and possibly C) from shallow soil water could potentially promote biotic Fe oxidation, a critical step in bedrock weathering, 7 m below. Together, these data suggest that C, Fe, and nutrient availability increase microbial Fe reduction and oxidation in surface (vs deeper) soil microsites despite high bulk O2, in contrast to the depth segregation of electron accepting processes often observed in aquatic ecosystems. Furthermore, the greatest capacity for Fe redox cycling can occur in A horizons that do not display gleying or mottling. decomposition, nutrient cycling, and mineral weathering, but factors controlling their rates and 21 spatial distribution with depth are poorly understood in terrestrial soils. In aquatic ecosystems, Fe 22 reduction often occurs below a zone of oxic sediments. We tested an alternative conceptual 23 model for Fe redox cycling in terrestrial soils using a deep humid tropical forest soil profile. We 24 hypothesized that Fe reduction in anaerobic microsites scales with depth variation in labile C and 25Fe availability, as opposed to bulk oxygen (O2). We measured bulk O2 at multiple depths from 26 0.1-5 m quasi-continuously over 18 months and sampled soils from surface to bedrock (~7 m). 27Median O2 mixing rati...

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High potential for iron reduction in upland soils

Cited by 37 publications

References 39 publications

Soil properties and sediment accretion modulate methane fluxes from restored wetlands

Soil properties and sediment accretion modulate methane fluxes from restored wetlands

Contrasting nitrogen fluxes in African tropical forests of the Congo Basin

Drivers and patterns of iron redox cycling from surface to bedrock in a deep tropical forest soil: a new conceptual model

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