Nitrogen availability regulates topsoil carbon dynamics after permafrost thaw by altering microbial metabolic efficiency

Chen, Leiyi; Liu, Li; Mao, Chengqiong; Qin, Shuqi; Wang, Jun; Liu, Futing; Blagodatsky, Sergey; Yang, Guibiao; Zhang, Qiwen; Zhang, Dianye; Yu, Jianliang; Yang, Yuanhe

doi:10.1038/s41467-018-06232-y

Cited by 171 publications

(119 citation statements)

References 68 publications

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“…Meanwhile, the shift from anoxic to oxic conditions may also stimulate root growth of plant species that prefer soil aerobic conditions (Iversen et al, ). This deduction was confirmed by the increased root biomass in the top 15 cm, with an increment of approximately 12.1–40.7 g m − 2 along the thaw sequence (Chen et al, ). Taken together, the increased root metabolism and biomass may promote plant N uptake, such as uptake of small organic N forms (peptides, amino acids, etc.…”

Section: Discussionmentioning

confidence: 85%

“…In addition, the MIM/GNM during the early thaw stage was similar to that in the control but increased during the middle and late thaw stages (Figure a), demonstrating that microbial N limitation became stronger along the thaw sequence. Such a pattern was supported by the increased stoichiometric imbalance between microorganisms and their resources (R C:N /B C:N ) after thermokarst formation (Chen et al, ), which also indicated enhanced microbial N limitation (Mooshammer et al, ). Moreover, the MIM/GNM was positively correlated with the R C:N /B C:N along this thaw sequence (Figure b).…”

Section: Resultsmentioning

confidence: 97%

“…Specifically, four sites were selected in this study area in early September, 2015 (Figure S1). One site in the undisturbed grassland without ground collapse, which was 5 m away from the gully, represented the control; the other three sites in the gully, with 50 to 90‐m interval between adjacent sites, referred to various permafrost thaw stages (Chen et al, ). The specific age of the selected site in the gully was obtained by dividing the distance between a specific site and the gully head by the extend speed, and the speed was acquired using Google Earth images (2007–2013) and repeated field surveys (2014–2016; Yang, Peng, Olefeldt, et al, ).…”

Section: Methodsmentioning

confidence: 99%

“…Soil samples at a depth of 0–15 cm were taken from the abovementioned four sites. Specifically, five independent plots (~3 × 5 m 2 ) were established in a 10 × 20 m 2 area within each site (Chen et al, ), and 10 soil cores were collected with a 3‐cm‐diameter stainless steel hand corer in each plot. Prior to all laboratory analyses, the 10 soil cores in each plot were homogenized after being sieved through 2‐mm mesh and then divided into three parts.…”

Section: Methodsmentioning

confidence: 99%

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Trajectory of Topsoil Nitrogen Transformations Along a Thermo‐Erosion Gully on the Tibetan Plateau

et al. 2019

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Permafrost thaw, especially thermokarst formation, that is, ground collapse due to thawing of ice‐rich permafrost, is expected to alter soil gross nitrogen (N) transformations, which can regulate plant productivity and ecosystem carbon cycle. However, it remains unclear how thermokarst formation modifies soil N processes in permafrost ecosystems. Here 15N pool dilution techniques were used to evaluate changes in topsoil gross N transformations during various thaw stages (early, middle, and late stages) along a thermo‐erosion gully on the Tibetan Plateau. Structural equation modeling was then conducted to explore the relative importance of biotic and abiotic factors in affecting soil gross N transformations. The results showed that topsoil gross N mineralization (GNM) decreased at the three stages, reflecting declined inorganic N production after permafrost collapse. In contrast, topsoil gross nitrification increased only during the early stage. Additionally, the ratio of microbial N immobilization to GNM was enhanced during the middle and late stages, indicating a stronger microbial N limitation after thermokarst formation. The structural equation modeling analysis revealed that soil moisture played an important role in modulating gross N transformations. For GNM, decreased soil moisture had inhibiting effects via regulating the microbial biomass, microbial community, and enzyme activities along the thaw sequence. For gross nitrification, declined soil moisture exerted facilitating effects directly by improving oxygen availability and indirectly by modulating the abundances of ammonia‐oxidizing archaea and bacteria during the early stage. Overall, these results demonstrated that thermokarst formation altered soil N processes, potentially triggering interactions between ecosystem N and carbon cycles after permafrost thaw.

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Section: Discussionmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Trajectory of Topsoil Nitrogen Transformations Along a Thermo‐Erosion Gully on the Tibetan Plateau

et al. 2019

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“…Furthermore, we found that the microbial metabolic quotient (qCO 2 ) was positively related to both R H ‐SOC new and RPE (Figure c). This suggests that an enhanced rhizodeposition by acquisitive species increase microbial allocation of energy to mineralization activities relative to growth (Shahzad et al, ), potentially in relation with a reduction in N availability by enhanced root N uptake, a lower carbon use efficiency and a faster turnover of microbial biomass (Chen et al, ; Sinsabaugh, Moorhead, Xu, & Litvak, ). This variation in microbial activity could also potentially be linked to the selection of rhizosphere microbiomes with contrasting SOC mineralization abilities by plant species with different economic strategies (Pascault et al, ; Schimel & Schaeffer, ).…”

Section: Discussionmentioning

confidence: 99%

Plant economic strategies of grassland species control soil carbon dynamics through rhizodeposition

Cros²,

et al. 2019

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The plant economics spectrum is increasingly recognized as a major determinant of plant species effects on terrestrial ecosystem functioning related to carbon cycling. However, the role of plant economic strategies in the effects of living root activity on soil organic carbon (SOC) dynamics through rhizodeposition remains unexplored, despite SOC being the largest terrestrial carbon pool. Using a continuous 13C‐labelling method allowing partitioning of plant and soil sources to carbon fluxes and pools, we studied here the linkages between plant economic strategies and SOC cycling processes in a ‘common garden’ greenhouse experiment. It includes a panel of 12 grassland species selected along a gradient of economic traits and belonging to three functionnal groups (C3 grasses, forbs and legumes). All species induced an acceleration of native SOC mineralization but this rhizosphere priming effect (RPE) substantially differed across species and varied eleven‐fold by the end of the experiment (from +26% to +295% relative to unplanted soil). Interspecific variation in RPE was primarily linked to plant photosynthetic activity associated to species economic strategies of light and CO2 resource acquisition and processing. Fast‐growing acquisitive species, such as legumes, featured large RPE, in relation with their high canopy photosynthesis coupled to high leaf photosynthetic capacity and large net primary productivity allocated above‐ground. This large RPE was further associated with high root metabolic activity, rhizodeposition and soil microbial activity. In contrast, fine‐root growth and economic traits related to soil resource foraging ability were poor predictors of RPE. The formation of new root‐derived SOC varied nine‐fold across species and was similarly positively related to the net primary productivity allocated above‐ground. Fast‐growing acquisitive species with a high photosynthetic activity induced a disproportionately large RPE relative to SOC formation. Synthesis. Overall, our study demonstrates that rhizodeposition is a major mechanism through which plant economic strategies of grassland species control soil carbon dynamics. Acquisitive versus conservative species were associated with high versus low rates of photosynthesis and rhizodeposition, in turn leading to fast versus slow SOC turnover. This emphasizes the importance of considering rhizosphere processes for understanding plant species effects on soil biogeochemistry.

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Morphological and physiological traits of dominant plant species in response to mowing in a temperate steppe

Zhang

Bai

et al. 2023

Ecological Applications

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Mowing is common grassland management to feed livestock during winter by harvesting hay in many high-latitude regions in autumn. The trait-based approach has been used to explain the responses of the plant community to disturbance resulting from environmental changes and human activities. However, few studies have focused on the mechanisms underlying the responses of grassland ecosystems to mowing from the perspective of plant traits. Here, we investigated the effects of mowing on the plant community of a temperate steppe in Inner Mongolia of northern China by field experiments to dissect the trade-off between morphological and physiological traits in response to shortterm (4 years) and long-term (16 years) mowing. Specifically, we evaluated the two strategies associated with the nutrient acquisition of two dominant species in response to mowing by measuring leaf and root morphological traits and physiological traits of root carboxylate exudation, arbuscular mycorrhizal fungi (AMF) colonization and soil microbial community. We found that long-term mowing, but not short-term mowing, led to an increase in species richness. In addition, mowing decreased the overall plant biomass of the grassland community, but enhanced and suppressed the growth of forbs and grasses, respectively. However, the ratio of forbs to grasses in the community was dependent on mowing duration, such that forbs became more dominant than the grasses under long-term mowing. Our results revealed that short-term mowing reduced soil microbial biodiversity and root colonization of AMF in the grass Stipa krylovii, while the root AMF colonization and carboxylate exudation in the forb Artemisia frigida were enhanced by short-term mowing. In long-term mowing, the functional traits associated with leaf resource conservation (i.e., leaf tissue density) and root resource acquisition were reduced in the grass, while the functional traits related to leaf resource acquisition and root resource conservation were increased in the forb, highlighting the species specificity and divergence in leaf and root traits in the grass and forb of temperate steppe in response to mowing. These novel findings demonstrate that physiological and morphological strategies are the main drivers for dominant species in response to mowing in temperate grasslands.

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Nitrogen availability regulates topsoil carbon dynamics after permafrost thaw by altering microbial metabolic efficiency

Cited by 171 publications

References 68 publications

Trajectory of Topsoil Nitrogen Transformations Along a Thermo‐Erosion Gully on the Tibetan Plateau

Trajectory of Topsoil Nitrogen Transformations Along a Thermo‐Erosion Gully on the Tibetan Plateau

Plant economic strategies of grassland species control soil carbon dynamics through rhizodeposition

Morphological and physiological traits of dominant plant species in response to mowing in a temperate steppe

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