scholarly journals Temporal, Spatial, and Temperature Controls on Organic Carbon Mineralization and Methanogenesis in Arctic High-Centered Polygon Soils

2021 ◽  
Vol 11 ◽  
Author(s):  
Taniya Roy Chowdhury ◽  
Erin C. Berns ◽  
Ji-Won Moon ◽  
Baohua Gu ◽  
Liyuan Liang ◽  
...  
Keyword(s):  
Water Content ◽  
Active Layer ◽  
Temporal Dynamics ◽  
The Arctic ◽  
Soil Conditions ◽  
Organic Soils ◽  
Tundra Soils ◽  
Organic C ◽  
Arctic Soils ◽  
Mineral Soils

Warming temperatures in continuous permafrost zones of the Arctic will alter both hydrological and geochemical soil conditions, which are strongly linked with heterotrophic microbial carbon (C) cycling. Heterogeneous permafrost landscapes are often dominated by polygonal features formed by expanding ice wedges: water accumulates in low centered polygons (LCPs), and water drains outward to surrounding troughs in high centered polygons (HCPs). These geospatial differences in hydrology cause gradients in biogeochemistry, soil C storage potential, and thermal properties. Presently, data quantifying carbon dioxide (CO2) and methane (CH4) release from HCP soils are needed to support modeling and evaluation of warming-induced CO2 and CH4 fluxes from tundra soils. This study quantifies the distribution of microbial CO2 and CH4 release in HCPs over a range of temperatures and draws comparisons to previous LCP studies. Arctic tundra soils were initially characterized for geochemical and hydraulic properties. Laboratory incubations at −2, +4, and +8°C were used to quantify temporal trends in CO2 and CH4 production from homogenized active layer organic and mineral soils in HCP centers and troughs, and methanogen abundance was estimated from mcrA gene measurements. Results showed that soil water availability, organic C, and redox conditions influence temporal dynamics and magnitude of gas production from HCP active layer soils during warming. At early incubation times (2–9 days), higher CO2 emissions were observed from HCP trough soils than from HCP center soils, but increased CO2 production occurred in center soils at later times (>20 days). HCP center soils did not support methanogenesis, but CH4-producing trough soils did indicate methanogen presence. Consistent with previous LCP studies, HCP organic soils showed increased CO2 and CH4 production with elevated water content, but HCP trough mineral soils produced more CH4 than LCP mineral soils. HCP mineral soils also released substantial CO2 but did not show a strong trend in CO2 and CH4 release with water content. Knowledge of temporal and spatial variability in microbial C mineralization rates of Arctic soils in response to warming are key to constraining uncertainties in predictive climate models.

scholarly journals Rainfall Alters Permafrost Soil Redox Conditions, but Meta-Omics Show Divergent Microbial Community Responses by Tundra Type in the Arctic

Soil Systems ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 17
Author(s):  
Karl J. Romanowicz ◽  
Byron C. Crump ◽  
George W. Kling
Keyword(s):  
Gene Expression ◽  
Anaerobic Metabolism ◽  
Cellular Growth ◽  
The Arctic ◽  
Soil Conditions ◽  
Tundra Soils ◽  
Ch4 Production ◽  
Soil Mesocosms ◽  
Tussock Tundra ◽  
O2 Concentration

Soil anoxia is common in the annually thawed surface (‘active’) layer of permafrost soils, particularly when soils are saturated, and supports anaerobic microbial metabolism and methane (CH4) production. Rainfall contributes to soil saturation, but can also introduce oxygen, causing soil oxidation and altering anoxic conditions. We simulated a rainfall event in soil mesocosms from two dominant tundra types, tussock tundra and wet sedge tundra, to test the impacts of rainfall-induced soil oxidation on microbial communities and their metabolic capacity for anaerobic CH4 production and aerobic respiration following soil oxidation. In both types, rainfall increased total soil O2 concentration, but in tussock tundra there was a 2.5-fold greater increase in soil O2 compared to wet sedge tundra due to differences in soil drainage. Metagenomic and metatranscriptomic analyses found divergent microbial responses to rainfall between tundra types. Active microbial taxa in the tussock tundra community, including bacteria and fungi, responded to rainfall with a decline in gene expression for anaerobic metabolism and a concurrent increase in gene expression for cellular growth. In contrast, the wet sedge tundra community showed no significant changes in microbial gene expression from anaerobic metabolism, fermentation, or methanogenesis following rainfall, despite an initial increase in soil O2 concentration. These results suggest that rainfall induces soil oxidation and enhances aerobic microbial respiration in tussock tundra communities but may not accumulate or remain in wet sedge tundra soils long enough to induce a community-wide shift from anaerobic metabolism. Thus, rainfall may serve only to maintain saturated soil conditions that promote CH4 production in low-lying wet sedge tundra soils across the Arctic.

scholarly journals Concepts of Soil Formation and Classification in Arctic Regions

ARCTIC ◽  
1958 ◽  
Vol 11 (3) ◽  
pp. 166 ◽  
Author(s):  
J.C.F. Tedrow ◽  
J.E. Cantlon
Keyword(s):  
Active Layer ◽  
Soil Formation ◽  
Tundra Soils ◽  
Arctic Regions ◽  
Arctic Soils ◽  
Free Drainage ◽  
Soil Forming Processes ◽  
Moisture Conditions ◽  
Northern Alaska ◽  
Selective Influence

Discusses, on basis of studies in northern Alaska, soil forming processes in arctic regions and considers the relation between vegetation and soils and problems of classification and mapping. Tundra soils are poorly drained, mineral in nature, and underlain by permafrost at depths of 1-2 ft Arctic brown soils form under free drainage, are mineral in character, and confined to ridges, terrace edges, and stabilized dunes. The active layer in such soils is usually deep. Downslope movement and frost action tend to disrupt any orderly morphology in both wet and well-drained sites. Moisture conditions in arctic soils exert a marked selective influence on vegetation.--from SIPRE.

scholarly journals From fibrous plant residues to mineral-associated organic carbon – the fate of organic matter in Arctic permafrost soils

2020 ◽  
Vol 17 (13) ◽  
pp. 3367-3383
Author(s):  
Isabel Prater ◽  
Sebastian Zubrzycki ◽  
Franz Buegger ◽  
Lena C. Zoor-Füllgraff ◽  
Gerrit Angst ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Organic Carbon ◽  
The Arctic ◽  
Plant Residues ◽  
N Losses ◽  
Organic C ◽  
Arctic Soils ◽  
C Cycle ◽  
C Stock

Abstract. Permafrost-affected soils of the Arctic account for 70 % or 727 Pg of the soil organic carbon (C) stored in the northern circumpolar permafrost region and therefore play a major role in the global C cycle. Most studies on the budgeting of C storage and the quality of soil organic matter (OM; SOM) in the northern circumpolar region focus on bulk soils. Thus, although there is a plethora of assumptions regarding differences in terms of C turnover or stability, little knowledge is available on the mechanisms stabilizing organic C in Arctic soils besides impaired decomposition due to low temperatures. To gain such knowledge, we investigated soils from Samoylov Island in the Lena River delta with respect to the composition and distribution of organic C among differently stabilized SOM fractions. The soils were fractionated according to density and particle size to obtain differently stabilized SOM fractions differing in chemical composition and thus bioavailability. To better understand the chemical alterations from plant-derived organic particles in these soils rich in fibrous plant residues to mineral-associated SOM, we analyzed the elemental, isotopic and chemical composition of particulate OM (POM) and clay-sized mineral-associated OM (MAOM). We demonstrate that the SOM fractions that contribute with about 17 kg C m−3 for more than 60 % of the C stock are highly bioavailable and that most of this labile C can be assumed to be prone to mineralization under warming conditions. Thus, the amount of relatively stable, small occluded POM and clay-sized MAOM that currently accounts with about 10 kg C m−3 for about 40 % of the C stock will most probably be crucial for the quantity of C protected from mineralization in these Arctic soils in a warmer future. Using δ15N as a proxy for nitrogen (N) balances indicated an important role of N inputs by biological N fixation, while gaseous N losses appeared less important. However, this could change, as with about 0.4 kg N m−3 one third of the N is present in bioavailable SOM fractions, which could lead to increases in mineral N cycling and associated N losses under global warming. Our results highlight the vulnerability of SOM in Arctic permafrost-affected soils under rising temperatures, potentially leading to unparalleled greenhouse gas emissions from these soils.

scholarly journals Improving the representation of fire disturbance in dynamic vegetation models by assimilating satellite data: a case study over the Arctic

2015 ◽  
Vol 8 (8) ◽  
pp. 2597-2609 ◽  
Author(s):  
E. P. Kantzas ◽  
S. Quegan ◽  
M. Lomas
Keyword(s):  
General Circulation ◽  
Temporal Dynamics ◽  
Fire Regime ◽  
Regional Scale ◽  
Net Ecosystem Exchange ◽  
The Arctic ◽  
Fire Intensity ◽  
Organic Soils ◽  
Fire Emissions ◽  
Vegetation Models

Abstract. Fire provides an impulsive and stochastic pathway for carbon from the terrestrial biosphere to enter the atmosphere. Despite fire emissions being of similar magnitude to net ecosystem exchange in many biomes, even the most complex dynamic vegetation models (DVMs) embedded in general circulation models contain poor representations of fire behaviour and dynamics, such as propagation and distribution of fire sizes. A model-independent methodology is developed which addresses this issue. Its focus is on the Arctic where fire is linked to permafrost dynamics and on occasion can release great amounts of carbon from carbon-rich organic soils. Connected-component labelling is used to identify individual fire events across Canada and Russia from daily, low-resolution burned area satellite products, and the obtained fire size probability distributions are validated against historical data. This allows the creation of a fire database holding information on area burned and temporal evolution of fires in space and time. A method of assimilating the statistical distribution of fire area into a DVM whilst maintaining its fire return interval is then described. The algorithm imposes a regional scale spatially dependent fire regime on a sub-scale spatially independent model; the fire regime is described by large-scale statistical distributions of fire intensity and spatial extent, and the temporal dynamics (fire return intervals) are determined locally. This permits DVMs to estimate many aspects of post-fire dynamics that cannot occur under their current representations of fire, as is illustrated by considering the modelled evolution of land cover, biomass and net ecosystem exchange after a fire.

scholarly journals Influence of Variability of Ryegrass Meadow Soil Conditions on their Natural and Utilization Values

2012 ◽  
Vol 40 (1) ◽  
pp. 163 ◽  
Author(s):  
Anna KRYSZAK ◽  
Agnieszka KLARZYNSKA ◽  
Jan KRYSZAK ◽  
Agnieszka STRYCHALSKA ◽  
Lukasz MACKOWIAK
Keyword(s):  
Moisture Content ◽  
Phosphorus Content ◽  
Floristic Composition ◽  
Soil Conditions ◽  
Organic Soils ◽  
Indicator Method ◽  
Multi Criteria Evaluation ◽  
Historical Distribution ◽  
Mineral Soils ◽  
Potassium Magnesium

The study presents the findings of research into the effect of the variability of site conditions on their floristic composition providinga basis for the identification of lower phytosociological units. Patches of Arrhenatheretum elatioris described with the assistance ofphytosociological surveys conducted using the Braun-Blanquet method were subjected to multi-criteria evaluation. On their basis, thefollowing parameters were determined: ecological and botanical structure, geographic-historical distribution, the structure of the lifegroupsof the floristic types identified, as well as natural values by the Oświt method and sward fodder value according to Filipek. In orderto determine the causes of the floristic variability observed, the following soil conditions were assessed: moisture content, soil reactionand nitrogen content by Ellenberg’s indicator method, as well as potassium, magnesium and phosphorus content by the appropriatelaboratory methods. Typical forms of Arrhenatheretum elatioris phytocenoses were found to develop on mucky soils in moderately moistsites. Patches of ryegrass occurring in sites with a periodically higher moisture content on organic soils refer to the Alopecuretum pratensisassociation. On the other hand, the sward of ryegrass meadows developed on dryer, mineral soils was characterised by increased numbersof species characteristic for xerothermic swards from the Festuco-Brometea class and sandy plant communities from the Koelerio glauca-Corynephoretea canescentis. More intensive utilization, primarily-fertilisation, was among the causes of the development of species-poorphytocenoses of low natural value but sward of a good fodder value.

scholarly journals Mean age of carbon in fine roots from temperate forests and grasslands with different management

2013 ◽  
Vol 10 (7) ◽  
pp. 4833-4843 ◽  
Author(s):  
E. Solly ◽  
I. Schöning ◽  
S. Boch ◽  
J. Müller ◽  
S. A. Socher ◽  
...  
Keyword(s):  
Species Diversity ◽  
Plant Species ◽  
Fine Roots ◽  
Fine Root ◽  
Plant Species Diversity ◽  
Soil Conditions ◽  
Organic Soils ◽  
Perennial Species ◽  
Organic C ◽  
The Mean

Abstract. Fine roots are the most dynamic portion of a plant's root system and a major source of soil organic matter. By altering plant species diversity and composition, soil conditions and nutrient availability, and consequently belowground allocation and dynamics of root carbon (C) inputs, land-use and management changes may influence organic C storage in terrestrial ecosystems. In three German regions, we measured fine root radiocarbon (14C) content to estimate the mean time since C in root tissues was fixed from the atmosphere in 54 grassland and forest plots with different management and soil conditions. Although root biomass was on average greater in grasslands 5.1 ± 0.8 g (mean ± SE, n = 27) than in forests 3.1 ± 0.5 g (n = 27) (p < 0.05), the mean age of C in fine roots in forests averaged 11.3 ± 1.8 yr and was older and more variable compared to grasslands 1.7 ± 0.4 yr (p < 0.001). We further found that management affects the mean age of fine root C in temperate grasslands mediated by changes in plant species diversity and composition. Fine root mean C age is positively correlated with plant diversity (r = 0.65) and with the number of perennial species (r = 0.77). Fine root mean C age in grasslands was also affected by study region with averages of 0.7 ± 0.1 yr (n = 9) on mostly organic soils in northern Germany and of 1.8 ± 0.3 yr (n = 9) and 2.6 ± 0.3 (n = 9) in central and southern Germany (p < 0.05). This was probably due to differences in soil nutrient contents and soil moisture conditions between study regions, which affected plant species diversity and the presence of perennial species. Our results indicate more long-lived roots or internal redistribution of C in perennial species and suggest linkages between fine root C age and management in grasslands. These findings improve our ability to predict and model belowground C fluxes across broader spatial scales.

Dissipation of Pendimethalin in Organic Soils in Florida

2014 ◽  
Vol 28 (1) ◽  
pp. 82-88 ◽  
Author(s):  
Dennis C. Odero ◽  
Dale L. Shaner
Keyword(s):  
Water Content ◽  
Soil Water Content ◽  
Weed Management ◽  
Soil Conditions ◽  
Organic Soils ◽  
Rapid Rate ◽  
Initial Amount ◽  
Water Based ◽  
Dry Soil ◽  
Rate Of Dissipation

Understanding the persistence of PRE-applied pendimethalin is important in determining timing of subsequent weed management programs in sugarcane on organic soils in the Everglades Agricultural Area (EAA). Dissipation of oil- and water-based pendimethalin formulations applied PRE at 2, 4, and 8 kg ai ha−1were compared in 2011 and 2012 on organic soils in the EAA. The rate of dissipation of both formulations was very similar. Both formulations had an initial rapid rate of dissipation followed by a slower rate of dissipation. However, the initial amount of pendimethalin in the soil was higher with the water-based compared to the oil-based formulation, most likely because of the lower volatility of the water-based formulation. The half-lives (DT50s) of the oil-based formulation were 32, 18, and 10 d and 8, 8, and 12 d at 2, 4, and 8 kg ha−1, respectively, in 2011 and 2012, respectively. The DT50s of the water-based formulation were 20, 13, and 10 d and 12, 12, and 14 d at 2, 4, and 8 kg ha−1, respectively in 2011 and 2012, respectively. These DT50values were attributed to low soil water content as well as the absence of incorporation following application. Our results suggest that dissipation of pendimethalin is rapid on organic soils irrespective of the formulation when applied under dry soil conditions with no incorporation into the soil.

scholarly journals Laboratory measurements of nitric oxide release from forest soil with a thick organic layer under different understory types

2010 ◽  
Vol 7 (5) ◽  
pp. 1425-1441 ◽  
Author(s):  
A. Bargsten ◽  
E. Falge ◽  
K. Pritsch ◽  
B. Huwe ◽  
F. X. Meixner
Keyword(s):  
Nitric Oxide ◽  
Water Content ◽  
Vegetation Type ◽  
Mineral Soil ◽  
Soil Conditions ◽  
Organic Layer ◽  
No Emission ◽  
Organic C ◽  
Physical And Chemical ◽  
No Fluxes

Abstract. Nitric oxide (NO) plays an important role in the photochemistry of the troposphere. NO from soil contributes up to 40% to the global budget of atmospheric NO. Soil NO emissions are primarily caused by biological activity (nitrification and denitrification), that occurs in the uppermost centimeter of the soil, a soil region often characterized by high contents of organic material. Most studies of NO emission potentials to date have investigated mineral soil layers. In our study we sampled soil organic matter under different understories (moss, grass, spruce and blueberries) in a humid mountainous Norway spruce forest plantation in the Fichtelgebirge (Germany). We performed laboratory incubation and flushing experiments using a customized chamber technique to determine the response of net potential NO flux to physical and chemical soil conditions (water content and temperature, bulk density, particle density, pH, C/N ratio, organic C, soil ammonium, soil nitrate). Net potential NO fluxes (in terms of mass of N) from soil samples taken under different understories ranged from 1.7–9.8 ng m−2 s−1 (soil sampled under grass and moss cover), 55.4–59.3 ng m−2 s−1 (soil sampled under spruce cover), and 43.7–114.6 ng m−2 s−1 (soil sampled under blueberry cover) at optimum water content and a soil temperature of 10 °C. The water content for optimum net potential NO flux ranged between 0.76 and 0.8 gravimetric soil moisture for moss covered soils, between 1.0 and 1.1 for grass covered soils, 1.1 and 1.2 for spruce covered soils, and 1.3 and 1.9 for blueberry covered soils. Effects of soil physical and chemical characteristics on net potential NO flux were statistically significant (0.01 probability level) only for NH4+. Therefore, as an alternative explanation for the differences in soil biogenic NO emission we consider more biological factors like understory vegetation type, amount of roots, and degree of mycorrhization; they have the potential to explain the observed differences of net potential NO fluxes.

scholarly journals Characterizing permafrost active layer dynamics and sensitivity to landscape spatial heterogeneity in Alaska

2018 ◽  
Vol 12 (1) ◽  
pp. 145-161 ◽  
Author(s):  
Yonghong Yi ◽  
John S. Kimball ◽  
Richard H. Chen ◽  
Mahta Moghaddam ◽  
Rolf H. Reichle ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Spatial Heterogeneity ◽  
Active Layer ◽  
The Arctic ◽  
Soil Conditions ◽  
Integrated Analysis ◽  
Active Layer Thickness ◽  
Modeling Framework ◽  
Discontinuous Permafrost ◽  
Recent Climate

Abstract. An important feature of the Arctic is large spatial heterogeneity in active layer conditions, which is generally poorly represented by global models and can lead to large uncertainties in predicting regional ecosystem responses and climate feedbacks. In this study, we developed a spatially integrated modeling and analysis framework combining field observations, local-scale ( ∼  50 m resolution) active layer thickness (ALT) and soil moisture maps derived from low-frequency (L + P-band) airborne radar measurements, and global satellite environmental observations to investigate the ALT sensitivity to recent climate trends and landscape heterogeneity in Alaska. Modeled ALT results show good correspondence with in situ measurements in higher-permafrost-probability (PP  ≥  70 %) areas (n = 33; R = 0.60; mean bias  =  1.58 cm; RMSE  =  20.32 cm), but with larger uncertainty in sporadic and discontinuous permafrost areas. The model results also reveal widespread ALT deepening since 2001, with smaller ALT increases in northern Alaska (mean trend  = 0.32±1.18 cm yr−1) and much larger increases (>  3 cm yr−1) across interior and southern Alaska. The positive ALT trend coincides with regional warming and a longer snow-free season (R =  0.60 ± 0.32). A spatially integrated analysis of the radar retrievals and model sensitivity simulations demonstrated that uncertainty in the spatial and vertical distribution of soil organic carbon (SOC) was the largest factor affecting modeled ALT accuracy, while soil moisture played a secondary role. Potential improvements in characterizing SOC heterogeneity, including better spatial sampling of soil conditions and advances in remote sensing of SOC and soil moisture, will enable more accurate predictions of active layer conditions and refinement of the modeling framework across a larger domain.

scholarly journals Laboratory measurements of nitric oxide release from forest soil with a thick organic layer under different understory types

2010 ◽  
Vol 7 (1) ◽  
pp. 203-250 ◽  
Author(s):  
A. Bargsten ◽  
E. Falge ◽  
B. Huwe ◽  
F. X. Meixner
Keyword(s):  
Nitric Oxide ◽  
Water Content ◽  
Mineral Soil ◽  
Soil Conditions ◽  
Organic Layer ◽  
No Emission ◽  
Organic C ◽  
Physical And Chemical ◽  
No Fluxes ◽  
No Emissions

Abstract. Nitric oxide (NO) plays an important role in the photochemistry of the troposphere. NO from soil contributes up to 40% to the global budget of atmospheric NO. Soil NO emissions are primarily caused by biological activity (nitrification and denitrification), that occurs in the uppermost centimetres of the soil, a soil region often characterized by high contents of organic material. Most studies of NO emission potentials to date have investigated mineral soil layers. In our study we sampled soil organic matter under different understories (moss, grass, spruce and blueberries) in a humid mountainous Norway spruce forest plantation in the Fichtelgebirge (Germany). We performed laboratory incubation and fumigation experiments using a customized chamber technique to determine the response of net potential NO flux to physical and chemical soil conditions (water content and temperature, bulk density, particle density, pH, C/N ratio, organic C, soil ammonium, soil nitrate). Net potential NO fluxes (in terms of mass of N) from soils of different understories ranged from 1.7–9.8 ng m−2 s−1 (grass and moss), 55.4–59.3 ng m−2 s−1 (spruce), and 43.7–114.6 ng m−2 s−1 (blueberry) at optimum water content and a soil temperature of 10°C. The water content for optimum net potential NO flux ranged between 0.76 and 0.8 gravimetric soil moisture for moss, between 1.0 and 1.1 for grass, 1.1 and 1.2 for spruce, and 1.3 and 1.9 for blueberries. Effects of soil physical and chemical characteristics on net potential NO flux were statistically significant (0.01 probability level) only for NH4+. Therefore, the effects of biogenic factors like understory type, amount of roots, and degree of mycorrhization on soil biogenic NO emission are discussed; they have the potential to explain the observed different of net potential NO fluxes. Quantification of NO emissions from the upmost soil layer is therefore an important step to quantify soil NO emissions in ecosystems with substantial organic soil horizons.

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