6 results on '"Bölscher, Tobias"'
Search Results
2. Beyond growth: The significance of non-growth anabolism for microbial carbon-use efficiency in the light of soil carbon stabilisation.
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Bölscher, Tobias, Vogel, Cordula, Olagoke, Folasade K., Meurer, Katharina H.E., Herrmann, Anke M., Colombi, Tino, Brunn, Melanie, and Domeignoz-Horta, Luiz A.
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CARBON in soils , *BIOSYNTHESIS , *MICROBIAL metabolites , *MICROBIAL physiology , *CARBON cycle - Abstract
Microbial carbon-use efficiency (CUE) in soils captures carbon (C) partitioning between anabolic biosynthesis of microbial metabolites and catabolic C emissions (i.e. respiratory C waste). The use of C for biosynthesis provides a potential for the accumulation of microbial metabolic residues in soil. Recognised as a crucial control in C cycling, microbial CUE is implemented in the majority of soil C models. Due to the models' high sensitivity to CUE, reliable soil C projections demand accurate CUE quantifications. Current measurements of CUE neglect microbial non-growth metabolites, such as extracellular polymeric substances (EPS) or exoenzymes, although they remain in soil and could be quantitatively important. Here, we highlight that disregarding non-growth anabolism can lead to severe underestimations of CUE. Based on two case studies, we demonstrate that neglecting exoenzyme and EPS production underestimates CUE by more than 100% and up to 30%, respectively. By incorporating these case-specific values in model simulations, we observed that the model projects up to 34% larger SOC stocks over a period of 64 years when non-growth metabolites are considered for estimating CUE, highlighting the crucial importance of accurate CUE quantification. Our considerations outlined here challenge the current ways how CUE is measured and we suggest improvements concerning the quantification of non-growth metabolites. Research efforts should focus on (i) advancing CUE estimations by capturing the multitude of microbial C uses, (ii) improving techniques to quantify non-growth metabolic products in soil, and (iii) providing an understanding of dynamic metabolic C uses under different environmental conditions and over time. In the light of current discussion on soil C stabilisation mechanisms, we call for efforts to open the 'black box' of microbial physiology in soil and to incorporate all quantitative important C uses in CUE measurements. [Display omitted] • Microbial carbon-use efficiency (CUE) is a crucial control of soil carbon cycling. • Current CUE measurements disregard carbon used for non-growth anabolism. • Current measurements of ' apparent ' CUE underestimate ' actual' CUE. • Underestimations of CUE can be large, with consequences for soil carbon projections. • To advance our understanding, we need to open the 'black box' of CUE. [ABSTRACT FROM AUTHOR]
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- 2024
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3. Temperature sensitivity of substrate-use efficiency can result from altered microbial physiology without change to community composition.
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Bölscher, Tobias, Herrmann, Anke M., Paterson, Eric, Freitag, Thomas, and Thornton, Barry
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CARBON in soils , *SOIL microbiology , *HUMUS , *MICROBIAL physiology , *BIOCHEMICAL substrates - Abstract
Mechanisms controlling carbon stabilisation in soil and its feedback to climate change are of considerable importance. Microbial substrate-use efficiency is an important property during decomposition of soil organic matter. It determines the allocation of substrate towards biosynthetic stabilisation of carbon and for respiratory losses into the atmosphere. Previously, it was observed that substrate-use efficiency declines with an increase in temperature and that it varies across organic substrates. Yet, our mechanistic understanding of processes causing the temperature sensitivity of substrate-use efficiency is limited. Changes in substrate-use efficiency could be triggered by (i) shifts in the active components of microbial communities, (ii) changes in microbial physiology within the same community, or (iii) a combination of both. In the present study, we evaluated the link between microbial community composition and substrate-use efficiency, combining measurements of carbon mineralisation and microbial energetics. We found only minor shifts in microbial community composition, despite large differences in substrate-use efficiencies across incubation temperatures and substrate additions. We conclude that short-term changes in substrate-use efficiency were mainly caused by changes in microbial physiology, but emphasize that future studies should focus on resolving long-term trade-offs between physiological and community influences on substrate-use efficiency. [ABSTRACT FROM AUTHOR]
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- 2017
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4. Response to Čapek and Šantrůčková's comment to "Liming effects on microbial carbon use efficiency and its potential consequences for soil organic carbon stocks" [Soil Bio. Biochem. 194: 109437].
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Schroeder, Julia, Dǎmǎtîrcǎ, Claudia, Bölscher, Tobias, Chenu, Claire, Elsgaard, Lars, Tebbe, Christoph C., Skadell, Laura, and Poeplau, Christopher
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CARBON in soils , *MICROBIAL respiration , *SODIC soils , *SOIL respiration , *MICROBIAL growth - Abstract
• Potential underestimation of microbial respiration in alkaline soils may affect CUE assessment. • The relative error in CUE is smaller because CUE is calculated from two C fluxes, i.e. microbial respiration and growth. • Given the different contribution of the respiration and growth flux, this bias is larger at low CUE as compared to high CUE. • It is not trivial to correct for this type of underestimation. [ABSTRACT FROM AUTHOR]
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- 2024
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5. Land-use alters the temperature response of microbial carbon-use efficiency in soils – a consumption-based approach.
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Bölscher, Tobias, Ågren, Göran I., and Herrmann, Anke M.
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SOIL temperature , *FOREST soils , *SOILS , *HISTOSOLS , *GRASSLAND soils , *TEMPERATURE , *SOIL stabilization - Abstract
Soil organic carbon (SOC) is a substantial source of atmospheric CO 2 , but also a large cause of uncertainties in Earth-system models. A principal control on soil CO 2 release is the carbon-use efficiency (CUE) of microbial communities, which partitions the carbon (C) allocation between biosynthetic stabilization and CO 2 respiration during SOC decomposition. In Earth-system models, CUE is commonly considered as a constant, although it should be susceptible to environmental factors such as temperature. We explored CUE across a set of land-uses and temperatures, and we show the hitherto neglected phenomenon that land-use can alter the temperature response of CUE. In arable soils, CUE was constant over a temperature range between 5 and 20 °C, but it decreased with temperature in ley farming, grassland, and forest soils at temperatures above 12.5 °C. The decrease in CUE was strongest for forest soils. Implementing our findings into a soil-C model revealed substantial differences in projected SOC losses: Assuming an increase of mean annual temperature of 2 or 4 °C, soils were projected to lose up to 6 or 15% of their current SOC, respectively, until they reach a new steady-state. These projections varied among land-uses. Our findings confront the current representation of CUE in global C models and challenges C sequestration strategies based on land-use changes, because land-uses such as e.g. forest ecosystems with current high C storage may lose substantially more C than agricultural soils due to strong declines of CUE. Image 1 • Temperature responses of carbon-use efficiency (CUE) differed across land-uses. • CUE decreased strongly in ley farming, grassland, and forest soils beyond 12.5 °C. • Land-use specific CUE temperature responses have profound impact on SOC projection. • Novel consumption-based thermodynamic approach ensures similar microbial workloads. • Microbial community composition was not a major driver of differences in CUE. [ABSTRACT FROM AUTHOR]
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- 2020
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6. Liming effects on microbial carbon use efficiency and its potential consequences for soil organic carbon stocks.
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Schroeder, Julia, Dǎmǎtîrcǎ, Claudia, Bölscher, Tobias, Chenu, Claire, Elsgaard, Lars, Tebbe, Christoph C., Skadell, Laura, and Poeplau, Christopher
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CARBON in soils , *SOIL acidity , *MICROBIAL respiration , *AGRICULTURE , *MICROBIAL growth , *SOIL microbial ecology - Abstract
Climate-smart agriculture aims amongst others at protecting and increasing soil organic carbon (SOC) stocks. The allocation of metabolised carbon (C) between soil microbial growth and respiration, i.e. C use efficiency (CUE) is crucial for SOC dynamics. We hypothesised that raising soil pH would alleviate CUE-limiting conditions and that liming could thus increase CUE, thereby supporting SOC accrual. This study investigated whether CUE can be manipulated by liming and how this might contribute to SOC stock changes. The effects of liming on CUE, microbial biomass C, abundance of microbial domains, SOC stocks and OC inputs were assessed for soils from three European long-term field experiments. Field control soils were additionally limed in the laboratory to assess immediate effects. The shift in soil pH H2O from 4.5 to 7.3 with long-term liming reduced CUE by 40 %, whereas the shift from 5.5 to 8.6 and from 6.5 to 7.8 was associated with increases in CUE by 16 % and 24 %, respectively. The overall relationship between CUE and soil pH followed a U-shaped (i.e. quadratic) curve, implying that in agricultural soils CUE may be lowest at pH H2O = 6.4. The immediate CUE response to liming followed the same trends. Changes in CUE with long-term liming contributed to the net effect of liming on SOC stocks. Our study confirms the value of liming as a management practice for climate-smart agriculture, but demonstrates that it remains difficult to predict the impact on SOC stocks due its complex effects on the C cycle. [Display omitted] • Liming altered CUE depending on the initial soil pH and the span of the pH shift. • At low pH, CUE declined with liming likely due to microbial community shifts. • At high pH, CUE increased with liming likely due to altered nutrient availability. • Liming increased microbial biomass C in all cases. • Changes in CUE with liming were not the primary cause for changes in SOC stocks. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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