Coupled dynamics of iron and iron-bound organic carbon in forest soils during anaerobic reduction

Abstract. Even though dissolved organic carbon (DOC) is the most active carbon (C) cycling in soil organic carbon (SOC) pools, it receives little attention from the global C budget. DOC fluxes are critical to aquatic ecosystem inputs and contribute to the C balance of terrestrial ecosystems, but few ecosystem models have attempted to integrate DOC dynamics into terrestrial C cycling. This study introduces a new process-based model, TRIPLEX-DOC, that is capable of estimating DOC dynamics in forest soils by incorporating both ecological drivers and biogeochemical processes. TRIPLEX-DOC was developed from Forest-DNDC, a biogeochemical model simulating C and nitrogen (N) dynamics, coupled with a new DOC process module that predicts metabolic transformations, sorption/desorption, and DOC leaching in forest soils. The model was validated against field observations of DOC concentrations and fluxes at white pine forest stands located in southern Ontario, Canada. The model was able to simulate seasonal dynamics of DOC concentrations and the magnitudes observed within different soil layers, as well as DOC leaching in the age sequence of these forests. Additionally, TRIPLEX-DOC estimated the effect of forest harvesting on DOC leaching, with a significant increase following harvesting, illustrating that land use change is of critical importance in regulating DOC leaching in temperate forests as an important source of C input to aquatic ecosystems.

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Effect of carbon and nitrogen addition on nitrous oxide and carbon dioxide fluxes from thawing forest soils

International Agrophysics ◽

10.1515/intag-2016-0065 ◽

2017 ◽

Vol 31 (3) ◽

pp. 339-349 ◽

Cited By ~ 4

Author(s):

Wu Haohao ◽

Xu Xingkai ◽

Duan Cuntao ◽

Li TuanSheng ◽

Cheng Weiguo

Keyword(s):

Carbon Dioxide ◽

Nitrous Oxide ◽

Soil Moisture ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Forest Soils ◽

Mixed Forest ◽

Soil Core ◽

Total N ◽

Nitrogen Inputs

AbstractPacked soil-core incubation experiments were done to study the effects of carbon (glucose, 6.4 g C m−2) and nitrogen (NH4Cl and KNO3, 4.5 g N m−2) addition on nitrous oxide (N2O) and carbon dioxide (CO2) fluxes during thawing of frozen soils under two forest stands (broadleaf and Korean pine mixed forest and white birch forest) with two moisture levels (55 and 80% water-filled pore space). With increasing soil moisture, the magnitude and longevity of the flush N2O flux from forest soils was enhanced during the early period of thawing, which was accompanied by great NO3−-N consumption. Without N addition, the glucose-induced cumulative CO2fluxes ranged from 9.61 to 13.49 g CO2-C m−2, which was larger than the dose of carbon added as glucose. The single addition of glucose increased microbial biomass carbon but slightly affected soil dissolved organic carbon pool. Thus, the extra carbon released upon addition of glucose can result from the decomposition of soil native organic carbon. The glucose-induced N2O and CO2fluxes were both significantly correlated to the glucose-induced total N and dissolved organic carbon pools and influenced singly and interactively by soil moisture and KNO3addition. The interactive effects of glucose and nitrogen inputs on N2O and CO2fluxes from forest soils after frost depended on N sources, soil moisture, and vegetation types.

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Iron-bound organic carbon in forest soils: quantification and characterization

Biogeosciences ◽

10.5194/bg-13-4777-2016 ◽

2016 ◽

Vol 13 (16) ◽

pp. 4777-4788 ◽

Cited By ~ 52

Author(s):

Qian Zhao ◽

Simon R. Poulson ◽

Daniel Obrist ◽

Samira Sumaila ◽

James J. Dynes ◽

...

Keyword(s):

Organic Carbon ◽

Spatial Variability ◽

Forest Soils ◽

The United States ◽

Biogeochemical Cycles ◽

Mean Annual Temperature ◽

Aliphatic Carbon ◽

A Site ◽

The Impact ◽

X Ray Absorption

Abstract. Iron oxide minerals play an important role in stabilizing organic carbon (OC) and regulating the biogeochemical cycles of OC on the earth surface. To predict the fate of OC, it is essential to understand the amount, spatial variability, and characteristics of Fe-bound OC in natural soils. In this study, we investigated the concentrations and characteristics of Fe-bound OC in soils collected from 14 forests in the United States and determined the impact of ecogeographical variables and soil physicochemical properties on the association of OC and Fe minerals. On average, Fe-bound OC contributed 37.8 % of total OC (TOC) in forest soils. Atomic ratios of OC : Fe ranged from 0.56 to 17.7, with values of 1–10 for most samples, and the ratios indicate the importance of both sorptive and incorporative interactions. The fraction of Fe-bound OC in TOC (fFe-OC) was not related to the concentration of reactive Fe, which suggests that the importance of association with Fe in OC accumulation was not governed by the concentration of reactive Fe. Concentrations of Fe-bound OC and fFe-OC increased with latitude and reached peak values at a site with a mean annual temperature of 6.6 °C. Attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR) and near-edge X-ray absorption fine structure (NEXAFS) analyses revealed that Fe-bound OC was less aliphatic than non-Fe-bound OC. Fe-bound OC also was more enriched in 13C compared to the non-Fe-bound OC, but C ∕ N ratios did not differ substantially. In summary, 13C-enriched OC with less aliphatic carbon and more carboxylic carbon was associated with Fe minerals in the soils, with values of fFe-OC being controlled by both sorptive and incorporative associations between Fe and OC. Overall, this study demonstrates that Fe oxides play an important role in regulating the biogeochemical cycles of C in forest soils and uncovers the governing factors for the spatial variability and characteristics of Fe-bound OC.

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Soil organic carbon in northern Spain (Galicia, Asturias, Cantabria and País Vasco)

Spanish Journal of Soil Science ◽

10.3232/sjss.2015.v5.n1.04 ◽

2015 ◽

Vol 5 ◽

Author(s):

Elías Luis Calvo ◽

Francisco Casás Sabarís ◽

Juan Manuel Galiñanes Costa ◽

Natividad Matilla Mosquera ◽

Felipe Macías Vázquez ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Forest Soils ◽

Agricultural Soils ◽

Calcareous Soils ◽

Mean Annual Precipitation ◽

Moisture Regime ◽

Organic Carbon Content ◽

Northern Spain ◽

Pais Vasco

The soil organic carbon content was analyzed in more than 7 000 soil samples under different land uses, climates and lithologies from northern Spain (Galicia, Asturias, Cantábria y País Vasco). GIS maps (1:50 000) were made of the % SOC and SOC stocks. The % SOC varies according to land use (higher in forest and scrub soils and lower in agricultural soils) and climate, and there is a highly significant correlation between SOC content and mean annual precipitation. There are significant differences between the soils of Galicia/Western Asturias (GAw) and those of the rest of the study area (Central and Eastern Asturias, Cantabria and País Vasco) (AceCV), although these are neighbouring regions. In forest and/or scrub soils with a udic soil moisture regime, in GAw, the SOC is usually > 7% and the average stocks 260 t ha -1 (0-30 cm), and >340 t ha-1 (0-50 cm) in soils with thick organic matter rich horizons (> 40 cm); these values greatly exceed the average contents observed in forest soils from temperate zones. Under similar conditions of vegetation and climate in soils of AceCV the SOC average is 3% and the mean stocks 90-100 t ha-1 (0-30 cm). The andic character of acid forest soils in GAw and the formation of C-Al,Fe complexes are pointed out as the SOC stabilization mechanism, in contrast to the neutral and calcareous soils that predominate in AceCV, where the main species of OC are easily biodegradable.

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Effect of Position and Slope Aspect on Organic Carbon, Total Nitrogen and Available Phosphorus in Forest Soils (Case Study: The Forest of Ilam Province, Dalab)

Journal of Water and Soil Science ◽

10.18869/acadpub.jstnar.19.71.109 ◽

2015 ◽

Vol 19 (71) ◽

pp. 109-117

Author(s):

M. Karamian ◽

V. Hosseini ◽

◽

Keyword(s):

Organic Carbon ◽

Total Nitrogen ◽

Forest Soils ◽

Slope Aspect ◽

Available Phosphorus

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Pedogenic Threshold in Acidity Explains Context-Dependent Tree Species Effects on Soil Carbon

Frontiers in Forests and Global Change ◽

10.3389/ffgc.2021.679813 ◽

2021 ◽

Vol 4 ◽

Author(s):

Ellen Desie ◽

Bart Muys ◽

Boris Jansen ◽

Lars Vesterdal ◽

Karen Vancampenhout

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Forest Soils ◽

Tree Species ◽

Litter Quality ◽

Species Selection ◽

Species Effects ◽

Tree Species Effects ◽

Soc Stocks ◽

The Way

Despite the general agreement that maximizing carbon storage and its persistence in forest soils are top priorities in the context of climate change mitigation, our knowledge on how to steer soil organic carbon (SOC) through forest management remains limited. For some soils, tree species selection based on litter quality has been shown a powerful measure to boost SOC stocks and stability, whereas on other locations similar efforts result in insignificant or even opposite effects. A better understanding of which mechanisms underpin such context-dependency is needed in order to focus and prioritize management efforts for carbon sequestration. Here we discuss the key role of acid buffering mechanisms in belowground ecosystem functioning and how threshold behavior in soil pH mediates tree species effects on carbon cycling. For most forests around the world, the threshold between the exchange buffer and the aluminum buffer around a pH-H2O of 4.5 is of particular relevance. When a shift between these buffer domains occurs, it triggers changes in multiple compartments in the soil, ultimately altering the way carbon is incorporated and transformed. Moreover, the impact of such a shift can be amplified by feedback loops between tree species, soil biota and cation exchange capacity (CEC). Hence, taking into account non-linearities related to acidity will allow more accurate predictions on the size and direction of the effect of litter quality changes on the way soil organic carbon is stored in forest soils. Consequently, this will allow developing more efficient, context-explicit management strategies to optimize SOC stocks and their stability.

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Iron-Bound Organic Carbon in Forest Soils: Quantification and Characterization

10.5194/bg-2015-587 ◽

2016 ◽

Author(s):

Qian Zhao ◽

Simon R. Poulson ◽

Daniel Obrist ◽

Samira Sumaila ◽

James J. Dynes ◽

...

Keyword(s):

Organic Carbon ◽

Forest Soils ◽

The United States ◽

Biogeochemical Cycles ◽

Attenuated Total Reflectance ◽

Mean Annual Temperature ◽

Aliphatic Carbon ◽

A Site ◽

The Impact ◽

X Ray Absorption

Abstract. Iron oxide minerals play an important role in stabilizing organic carbon (OC) and regulating the biogeochemical cycles of OC on the earth surface. To predict the fate of OC, it is essential to completely understand the amount, spatial variability and characteristics of Fe-bound OC in natural soils. In this study, we investigated the concentrations and characteristics of Fe-bound OC in soils collected from 14 forests in the United States, and determined the impact of ecogeographical variables and soil physicochemical properties o n the association of OC and Fe minerals. We found that Fe-bound OC contributed up to 57.8 % of total OC (TOC) in forest soils. Atomic ratios of OC:Fe ranged from 0.56 to 17.7 with values of 1–10 for most samples, and these ratios indicate an importance of both sorptive and incorporativ e interactions. The fraction of Fe-bound OC in TOC (fFe-OC) was not related to the concentration of reactive Fe, which suggests that the importance of association with Fe in OC accumulation was not governed by the concentration of reactive Fe. Concentrations of Fe-bound OC and fFe-OC increased with the latitude and reached peak values at a site with a mean annual temperature of 6.6 °C Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and near-edge X-ray absorption fine structure (NEXAFS) analyses revealed that Fe-bound OC was less aliphatic than non-Fe-bound OC. Fe-bound OC also was more enriched in 13C compared to the non-Fe-bound OC, but C/N ratios did not differ substantially. In summary, 13C-enriched OC with less aliphatic carbon and more carboxylic carbon was associated with Fe minerals in the soils, with values of fFe-OC being controlled by both sorptive and incorporative associations between Fe and OC. Overall, this study demonstrates that Fe oxides play an important role in regulating the biogeochemical cycles of C in forest soils, and uncovers the governing factors for the spa tial variability and characteristics of Fe-bound OC.

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