The Ecology of Soil Carbon: Pools, Vulnerabilities, and Biotic and Abiotic Controls

Jackson, Robert B.; Lajtha, Kate; Crow, Susan E.; Hugelius, Gustaf; Kramer, Marc G.; Piñeiro, Gervasio

doi:10.1146/annurev-ecolsys-112414-054234

Cited by 792 publications

(587 citation statements)

References 181 publications

(186 reference statements)

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“…Soil C is not permitted below 3.5 m in CLM4.5, or in most analogous models, such that potential decomposition of the ∼ 350 Pg soil organic C in deep permafrost (yedoma C, > 3 m) is not accounted for (Hugelius et al, 2014;Jackson et al, 2017). This is significant for our simulations, which show frequent talik formation and accelerating thaw volumes below 3 m (e.g., Fig.…”

Section: Discussionmentioning

confidence: 94%

“…These processes can initiate formation of a talik zone (perennially thawed subsurface soils) during active layer adjustment to new thermal regimes (Jorgenson et al, 2010) in lake and non-lake environments. Talik as well as longer, deeper active layer thaw stimulate respiration of soil C (Romanovsky and Osterkamp, 2000;, making the ∼ 1035 Pg soil organic carbon in near surface permafrost (0-3 m) and ∼ 350 Pg soil organic carbon in deep permafrost (> 3 m) vulnerable to decomposition (Hugelius et al, 2014;Jackson et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Detecting the permafrost carbon feedback: talik formation and increased cold-season respiration as precursors to sink-to-source transitions

et al. 2018

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Abstract. Thaw and release of permafrost carbon (C) due to climate change is likely to offset increased vegetation C uptake in northern high-latitude (NHL) terrestrial ecosystems. Models project that this permafrost C feedback may act as a slow leak, in which case detection and attribution of the feedback may be difficult. The formation of talik, a subsurface layer of perennially thawed soil, can accelerate permafrost degradation and soil respiration, ultimately shifting the C balance of permafrost-affected ecosystems from long-term C sinks to long-term C sources. It is imperative to understand and characterize mechanistic links between talik, permafrost thaw, and respiration of deep soil C to detect and quantify the permafrost C feedback. Here, we use the Community Land Model (CLM) version 4.5, a permafrost and biogeochemistry model, in comparison to long-term deep borehole data along North American and Siberian transects, to investigate thaw-driven C sources in NHL (> 55∘ N) from 2000 to 2300. Widespread talik at depth is projected across most of the NHL permafrost region (14 million km2) by 2300, 6.2 million km2 of which is projected to become a long-term C source, emitting 10 Pg C by 2100, 50 Pg C by 2200, and 120 Pg C by 2300, with few signs of slowing. Roughly half of the projected C source region is in predominantly warm sub-Arctic permafrost following talik onset. This region emits only 20 Pg C by 2300, but the CLM4.5 estimate may be biased low by not accounting for deep C in yedoma. Accelerated decomposition of deep soil C following talik onset shifts the ecosystem C balance away from surface dominant processes (photosynthesis and litter respiration), but sink-to-source transition dates are delayed by 20–200 years by high ecosystem productivity, such that talik peaks early (∼ 2050s, although borehole data suggest sooner) and C source transition peaks late (∼ 2150–2200). The remaining C source region in cold northern Arctic permafrost, which shifts to a net source early (late 21st century), emits 5 times more C (95 Pg C) by 2300, and prior to talik formation due to the high decomposition rates of shallow, young C in organic-rich soils coupled with low productivity. Our results provide important clues signaling imminent talik onset and C source transition, including (1) late cold-season (January–February) soil warming at depth (∼ 2 m), (2) increasing cold-season emissions (November–April), and (3) enhanced respiration of deep, old C in warm permafrost and young, shallow C in organic-rich cold permafrost soils. Our results suggest a mosaic of processes that govern carbon source-to-sink transitions at high latitudes and emphasize the urgency of monitoring soil thermal profiles, organic C age and content, cold-season CO2 emissions, and atmospheric 14CO2 as key indicators of the permafrost C feedback.

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Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Detecting the permafrost carbon feedback: talik formation and increased cold-season respiration as precursors to sink-to-source transitions

et al. 2018

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“…Litters with labile C compounds and high N concentrations generally have high turnover rates, whereas recalcitrant C compounds like lignin, and low litter nutrient concentrations have been related to low litter decomposition rates (Cornwell et al 2008;Freschet et al 2013). To date, most decomposition studies have focussed on turn-over of aboveground plant material despite the fact that belowground plant input can be substantial (Freschet et al 2013;Roumet et al 2016;Jackson et al 2017): roots account for 33% annual biomass input in natural grasslands (Freschet et al 2013). In agricultural systems aboveground biomass is harvested, thus root biomass forms the predominant biomass input of C and nutrients by crops.…”

Section: Plant Legacy Effects On Litter Decompositionmentioning

confidence: 99%

“…Plant roots are a major contribution to C-cycling (Freschet et al 2013;Jackson et al 2017), but literature on root decomposition is scarce. Comparing root to shoot decomposition is highly relevant because significant coordination would make shoot decomposition a valuable proxy for root decomposition.…”

Section: Introductionmentioning

confidence: 99%

“…Roots account up to 60% of primary productivity in grasslands (Jackson et al 2017), and are estimated to represent 33% of the average annual litter input (Freschet et al 2013). In croplands, roots represent 10% of plant biomass production, of which 46% C is retained in soil organic matter versus only 8% of aboveground C as most aboveground material is harvested while roots remain in soil (Jackson et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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A plant’s inheritance : Soil legacy effects of crops and wild relatives in relation to plant functional traits

Barel¹

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During crop domestication plant characteristics have been artificially selected for, with potential unwanted side-effects as some characteristics might have been altered unintentionally. Since productivity in agriculture relies on the interactions between plant and soil, it is a necessity to study the relationship between plant traits, decomposition, microbial community composition and the possible effects on future plant growth.This thesis presents results from several experiments studying how plants influence the soil, through decomposition of plant residues, the soil microbial community assemblage, and its possible consequence for subsequent plant growth. In a crop rotation experiment plant-soil feedback effects have been studied at field scale, with legacy effects of winter cover crops as the primary focus. Influences of plant traits on litter decomposition and microbial community were studied both in a field context and under controlled greenhouse conditions. By comparing the legacy effects of crops with close-relatives from natural grasslands the effects of domestication on litter decomposition and rhizosphere microbial community composition were explored.In the field experiment, it was observed that mixtures of cover crops can perform better than the sum of their parts when the plants in the mixture complemented each other during their growth. Productivity and quality of cover crops was found to promote growth of subsequent main crops, in part through stimulation of soil fungal biomass and feedback effects of decomposing litter. In the greenhouse, growing plants were observed to suppress decomposition of root and shoot litter to varying extent depending on which plant was present and on the quality of the decomposing litter. The results also indicate that domestication has affected plant functional traits in a variety of ways, rather than having predictable effects across a range of crops. Plant functional traits are a useful approach to study legacy effects, as they predict decomposability of plant residues and partially explain the microbial community composition in the rhizosphere. Significance of plant traits as predictors varied with environmental conditions, thus interpretation of the results should be related to its context. This thesis contributes to the understanding of plant-soil interactions, with emphasis on differences and similarities of agricultural and natural ecosystems.

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Interconnecting Soil Organic Matter With Nitrogen and Phosphorus Cycling

Celi¹,

Said‐Pullicino²,

Bol³

et al. 2022

Multi‐Scale Biogeochemical Processes in Soil Ecosystems

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The Ecology of Soil Carbon: Pools, Vulnerabilities, and Biotic and Abiotic Controls

Cited by 792 publications

References 181 publications

Detecting the permafrost carbon feedback: talik formation and increased cold-season respiration as precursors to sink-to-source transitions

Detecting the permafrost carbon feedback: talik formation and increased cold-season respiration as precursors to sink-to-source transitions

A plant’s inheritance : Soil legacy effects of crops and wild relatives in relation to plant functional traits

Interconnecting Soil Organic Matter With Nitrogen and Phosphorus Cycling

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