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Schleucher, Jürgen, Professor
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Publications (10 of 85) Show all publications
Segura, J. H., Nilsson, M. B., Sparrman, T., Serk, H., Schleucher, J., Tolu, J. & Öquist, M. G. (2019). Boreal tree species affect soil organic matter composition and saprotrophic mineralization rates. Plant and Soil, 441(1-2), 173-190
Open this publication in new window or tab >>Boreal tree species affect soil organic matter composition and saprotrophic mineralization rates
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2019 (English)In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 441, no 1-2, p. 173-190Article in journal (Refereed) Published
Abstract [en]

Aims: To investigate how different tree species affect the composition of SOM and its mineralization in boreal forest ecosystems.

Methods: We used pyrolysis GC-MS for molecular-level characterization of the SOM formed under five common boreal tree species at a replicated field experiment similar to 50years after plantation. We incubated soil samples at 4, 9, 14 and 19 degrees C and measured inherent CO2 production and substrate-induced respiration. We then evaluated if the saprotrophic microbial activity and its temperature sensitivity was controlled by the SOM composition.

Results: The molecular composition of the SOM emerged as key factor influencing SOM properties in plots with different tree species. Most of the variance in the SOM content was explained by the organo-chemical composition of the SOM. More importantly, the fraction of the microbial community able to utilize the native SOM was largely controlled by the SOM organo-chemical composition. Temperature sensitivity of CO2 production (Q(10)) was not explained by SOM composition. However, the microbial access to different SOM pools varied with temperature.

Conclusions: These results bridge the gap between the paradigms of short-term litter and long-term SOM decomposition showing that, on an intermediate timescale (similar to 50 years), boreal tree species affect SOM molecular composition and saprotrophic mineralization rates.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Boreal forest, Soil organic matter, Organo-chemical composition, Microbial respiration, Q(10), Q(R), Pyrolysis-GC-MS
National Category
Forest Science
Identifiers
urn:nbn:se:umu:diva-163690 (URN)10.1007/s11104-019-04105-x (DOI)000482412400011 ()
Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-17Bibliographically approved
Segura, J. H., Nilsson, M. B., Schleucher, J., Haei, M., Sparrman, T., Székely, A., . . . Öquist, M. G. (2019). Microbial utilization of simple carbon substrates in boreal peat soils at low temperatures. Soil Biology and Biochemistry, 135, 438-448
Open this publication in new window or tab >>Microbial utilization of simple carbon substrates in boreal peat soils at low temperatures
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2019 (English)In: Soil Biology and Biochemistry, ISSN 0038-0717, E-ISSN 1879-3428, Vol. 135, p. 438-448Article in journal (Refereed) Published
Abstract [en]

Boreal peatlands are key high-latitude ecosystem types and act as a carbon (C) sink storing an estimated 25% of the world's soil C. These environments are currently seeing the most substantial changing climate, especially during the winter. CO2 emissions during the winter can correspond to 80% of the growing season's net CO2 assimilation. Yet, our conceptual understanding of the controls on microbial metabolic activity in peat soils at temperatures ≤0 °C is poor. We used stable isotope probing of peat samples and tracked the fate of 13C-glucose using 13C-NMR. We show that microorganisms in frozen boreal peat soils utilize monomeric C-substrates to sustain both catabolic and anabolic metabolism at temperatures down to −5 °C. The 13C-substrate was transformed into 13C–CO2, different metabolites, and incorporated into membrane phospholipid fatty acids. The 16S rRNA-based community analyses revealed the activity at −3 °C changes the composition of the bacterial community over relevant timescales. Below 0 °C, small temperature changes have strong effects on process rates and small differences in winter soil temperature may affect C dynamics of northern peatlands. Understanding biological processes at low and below zero temperatures are central for the overall functioning of these systems representing one of the world's major soil C pools.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Frozen peat soils, Microbial activity, Metabolism, C-13-NMR, DNA, Carbon cycling
National Category
Soil Science
Identifiers
urn:nbn:se:umu:diva-162400 (URN)10.1016/j.soilbio.2019.06.006 (DOI)000477689700051 ()2-s2.0-85067368525 (Scopus ID)
Available from: 2019-08-19 Created: 2019-08-19 Last updated: 2019-10-17Bibliographically approved
Baskaran, P., Ekblad, A., Soucémarianadin, L. N., Hyvönen, R., Schleucher, J. & Lindahl, B. D. (2019). Nitrogen dynamics of decomposing Scots pine needle litter depends on colonizing fungal species. FEMS Microbiology Ecology, 95(6), Article ID fiz059.
Open this publication in new window or tab >>Nitrogen dynamics of decomposing Scots pine needle litter depends on colonizing fungal species
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2019 (English)In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 95, no 6, article id fiz059Article in journal (Refereed) Published
Abstract [en]

In boreal ecosystems plant production is often limited by low availability of nitrogen. Nitrogen retention in below-ground organic pools plays an important role in restricting recirculation to plants and thereby hampers forest production. Saprotrophic fungi are commonly assigned to different decomposer strategies, but how these relate to nitrogen cycling remains to be understood. Decomposition of Scots pine needle litter was studied in axenic microcosms with the ligninolytic litter decomposing basidiomycete Gymnopus androsaceus or the stress tolerant ascomycete Chalara longipes. Changes in chemical composition were followed by C-13 CP/MAS NMR spectroscopy and nitrogen dynamics was assessed by the addition of a N-15 tracer. Decomposition by C. longipes resulted in nitrogen retention in non-hydrolysable organic matter, enriched in aromatic and alkylic compounds, whereas the ligninolytic G. androsaceus was able to access this pool, counteracting nitrogen retention. Our observations suggest that differences in decomposing strategies between fungal species play an important role in regulating nitrogen retention and release during litter decomposition, implying that fungal community composition may impact nitrogen cycling at the ecosystem level.

Place, publisher, year, edition, pages
Oxford University Press, 2019
Keywords
saprotrophic fungi, litter decomposition, C-13 CP/MAS NMR, nitrogen cycling, N-15 tracer, functional guilds
National Category
Soil Science Environmental Sciences related to Agriculture and Land-use
Identifiers
urn:nbn:se:umu:diva-161859 (URN)10.1093/femsec/fiz059 (DOI)000474762800003 ()31069387 (PubMedID)
Available from: 2019-08-07 Created: 2019-08-07 Last updated: 2019-10-17Bibliographically approved
Cormier, M.-A., Werner, R. A., Sauer, P. E., Gröcke, D. R., Leuenberger, M. C., Wieloch, T., . . . Kahmen, A. (2018). 2H-fractionations during the biosynthesis of carbohydrates and lipids imprint a metabolic signal on the δ2H values of plant organic compounds. New Phytologist, 218(2), 479-491
Open this publication in new window or tab >>2H-fractionations during the biosynthesis of carbohydrates and lipids imprint a metabolic signal on the δ2H values of plant organic compounds
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2018 (English)In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 218, no 2, p. 479-491Article in journal (Refereed) Published
Abstract [en]

Hydrogen (H) isotope ratio (δ2H) analyses of plant organic compounds have been applied to assess ecohydrological processes in the environment despite a large part of the δ2H variability observed in plant compounds not being fully elucidated.

We present a conceptual biochemical model based on empirical H isotope data that we generated in two complementary experiments that clarifies a large part of the unexplained variability in the δ2H values of plant organic compounds.

The experiments demonstrate that information recorded in the δ2H values of plant organic compounds goes beyond hydrological signals and can also contain important information on the carbon and energy metabolism of plants. Our model explains where 2H‐fractionations occur in the biosynthesis of plant organic compounds and how these 2H‐fractionations are tightly coupled to a plant's carbon and energy metabolism. Our model also provides a mechanistic basis to introduce H isotopes in plant organic compounds as a new metabolic proxy for the carbon and energy metabolism of plants and ecosystems.

Such a new metabolic proxy has the potential to be applied in a broad range of disciplines, including plant and ecosystem physiology, biogeochemistry and palaeoecology.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2018
Keywords
alkanes, biomarker, cellulose, hydrogen isotopes, plant metabolism
National Category
Other Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-145979 (URN)10.1111/nph.15016 (DOI)000428070100011 ()29460486 (PubMedID)
Available from: 2018-03-24 Created: 2018-03-24 Last updated: 2019-01-07Bibliographically approved
Schleucher, J., Wieloch, T., Serk, H., Immerzeel, P., Ehlers, I., Nilsson, M. & Zuidema, P. (2018). Intramolecular stable isotope variation: Consequences for conventional isotope measurements and elucidation of new ecophysiological signals. In: Geophysical Research Abstracts: . Paper presented at EGU General Assembly 2018, Vienna, Austria, April 8-13, 2018. EGU, 20, Article ID EGU2018-5511.
Open this publication in new window or tab >>Intramolecular stable isotope variation: Consequences for conventional isotope measurements and elucidation of new ecophysiological signals
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2018 (English)In: Geophysical Research Abstracts, EGU , 2018, Vol. 20, article id EGU2018-5511Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Isotope ratios (13C/12C and 2H/1H) have long been used in plant ecophysiology and for reconstruction of environmental variables. For decades it has also been known that heavy isotopes are distributed unevenly IN biological metabolites. In other words, the isotopomers of metabolites have unequal abundances. Consequently, conventional δ values are whole-molecule averages over varying intramolecular values. However, this biochemical knowledge has not been applied in plant ecophysiology or biogeochemistry, because the first measurements of intramolecular isotope distributions were extremely cumbersome, requiring breakdown of metabolites into small molecules and IRMS measurements on those. Since then, NMR methodology has advanced so that intramolecular isotope distributions can routinely be measured (Chaintreau et al., Anal. Chim. Acta 2013), although large samples are needed. Here we demonstrate the importance of intramolecular isotope distributions with several examples.

1. We show that 13C is distributed unevenly in tree-ring cellulose. While this is not surprising given previous observations, it has important consequences: When wood enters soil organic matter and is broken down, the δ13C of respired CO2 will only follow δ13C of cellulose if the glucose units are fully respired. If part of the glucose molecules enters other pathways, such as the oxidative pentose phosphate pathway, δ13C of liberated CO2 can deviate markedly from the whole-molecule value. This may have consequences for using δ13C of CO2 to unravel ecosystem C exchange fluxes.

2. Intramolecular isotope distributions are created by enzyme isotope effects, hence they constitute fingerprints of biosynthetic pathways and can report on regulation of metabolism on time scales up to millennia. As particular advantage, this information can be encoded in ratios of isotopomer abundances (Augusti et al., Chem. Geol. 2008), and can be extracted independent of the isotope ratio of the whole molecule, and of the isotope source (Ehlers et al., PNAS 2015).

3. We demonstrate that intramolecular 13C distributions of the glucose units of tree-ring cellulose vary over time. This implies that 13C fractionations mechanisms beyond the well-known stomata-Rubisco mechanism exist. The time-dependent intramolecular variation constitutes new ecophysiological information.

4. When δ13C or δD are used as proxies for ecophysiological parameters, correlation coefficients between both quantities are restricted to low values, limiting the power of isotope-based reconstructions. We show that this limitation is at least partly caused by intramolecular isotope variation. Conversely, higher correlation coefficients can be observed between intramolecular isotope parameters – position-specific carbon isotope ratios or deuterium isotopomer ratios – and ecophysiological parameters. Thus, intramolecular isotope data allow for more powerful reconstructions of physiological and environmental parameters

Place, publisher, year, edition, pages
EGU, 2018
National Category
Natural Sciences
Identifiers
urn:nbn:se:umu:diva-145981 (URN)
Conference
EGU General Assembly 2018, Vienna, Austria, April 8-13, 2018
Available from: 2018-03-24 Created: 2018-03-24 Last updated: 2020-03-04Bibliographically approved
Wieloch, T., Ehlers, I., Yu, J., Frank, D., Grabner, M., Gessler, A. & Schleucher, J. (2018). Intramolecular 13C analysis of tree rings provides multiple plant ecophysiology signals covering decades. Scientific Reports, 8, Article ID 5048.
Open this publication in new window or tab >>Intramolecular 13C analysis of tree rings provides multiple plant ecophysiology signals covering decades
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 5048Article in journal (Refereed) Published
Abstract [en]

Measurements of carbon isotope contents of plant organic matter provide important information in diverse fields such as plant breeding, ecophysiology, biogeochemistry and paleoclimatology. They are currently based on 13C/12C ratios of specific, whole metabolites, but we show here that intramolecular ratios provide higher resolution information. In the glucose units of tree-ring cellulose of 12 tree species, we detected large differences in 13C/12C ratios (>10‰) among carbon atoms, which provide isotopically distinct inputs to major global C pools, including wood and soil organic matter. Thus, considering position-specific differences can improve characterisation of soil-to-atmosphere carbon fluxes and soil metabolism. In a Pinus nigra tree-ring archive formed from 1961 to 1995, we found novel 13C signals, and show that intramolecular analysis enables more comprehensive and precise signal extraction from tree rings, and thus higher resolution reconstruction of plants’ responses to climate change. Moreover, we propose an ecophysiological mechanism for the introduction of a 13C signal, which links an environmental shift to the triggered metabolic shift and its intramolecular 13C signature. In conclusion, intramolecular 13C analyses can provide valuable new information about long-term metabolic dynamics for numerous applications.

National Category
Other Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:umu:diva-145978 (URN)10.1038/s41598-018-23422-2 (DOI)000428033900002 ()29567963 (PubMedID)
Funder
Knut and Alice Wallenberg Foundation, 2015.0047
Available from: 2018-03-24 Created: 2018-03-24 Last updated: 2019-10-17Bibliographically approved
Wieloch, T., Ehlers, I., Yu, J., Frank, D., Grabner, M., Gessler, A. & Schleucher, J. (2018). Tree-ring cellulose exhibits several interannual 13C signals on the intramolecular level. In: Geophysical Research Abstracts: . Paper presented at EGU General Assembly 2018, Vienna, Austria, April 8-13, 2018. , 20, Article ID EGU2018-17509-2.
Open this publication in new window or tab >>Tree-ring cellulose exhibits several interannual 13C signals on the intramolecular level
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2018 (English)In: Geophysical Research Abstracts, 2018, Vol. 20, article id EGU2018-17509-2Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Measurements of carbon isotope contents (13C/12C, δ 13C) in tree rings provide retrospective information about the short and long-term dynamics of plant ecophysiological, and paleo-environmental traits. They are commonly based on 13C/12C ratios of cellulose, and interpreted with respect to fractionation related to CO2 diffusion into plants and its fixation by Rubisco (diffusion-Rubisco - DR - fractionation). However, primary metabolites such as glucose are known to exhibit intramolecular 13C/12C differences of the order of 10h which reflect 13C fractionation by enzyme reactions downstream of Rubisco (Post-Rubisco - PR - fractionation). PR fractionation is not commonly considered in dendrochronological studies. It has not yet been investigated whether glucose monomers of cellulose show intramolecular 13C differences. Furthermore, it is unknown whether PR fractionation varies among years, and whether DR and PR fractionations introduce distinct 13C/12C signals. To test this, we isolated the glucose monomers of Pinus nigra tree rings, and determined 13C/12C ratios of all intramolecular glucose carbon positions by quantitative 13C NMR. The resulting dataset consists of 6 time series of positional 13C/12C ratios with annual resolution, extending from 1961 to 1995. Tree-ring glucose exhibits intramolecular 13C/12C differences of the order of 10h. Cluster analysis revealed several independent intramolecular 13C signals. These signals constitute distinct channels of information about both the DR interface and associated environmental triggers, as well as PR processes related to downstream C allocation. Thus, analysis of intramolecular 13C signals can extract more information with better quality from tree rings. This might enhance our understanding of biogeochemical, ecophysiological and paleo-environmental phenomena.

National Category
Natural Sciences
Identifiers
urn:nbn:se:umu:diva-145982 (URN)
Conference
EGU General Assembly 2018, Vienna, Austria, April 8-13, 2018
Available from: 2018-03-24 Created: 2018-03-24 Last updated: 2020-03-06Bibliographically approved
Segura, J. H., Nilsson, M. B., Haei, M., Sparrman, T., Mikkola, J.-P., Gräsvik, J., . . . Öquist, M. G. (2017). Microbial mineralization of cellulose in frozen soils. Nature Communications, 8(1), Article ID 1154.
Open this publication in new window or tab >>Microbial mineralization of cellulose in frozen soils
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2017 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, no 1, article id 1154Article in journal (Refereed) Published
Abstract [en]

High-latitude soils store ~40% of the global soil carbon and experience winters of up to 6 months or more. The winter soil CO2 efflux importantly contributes to the annual CO2 budget. Microorganisms can metabolize short chain carbon compounds in frozen soils. However, soil organic matter (SOM) is dominated by biopolymers, requiring exoenzymatic hydrolysis prior to mineralization. For winter SOM decomposition to have a substantial influence on soil carbon balances it is crucial whether or not biopolymers can be metabolized in frozen soils. We added 13C-labeled cellulose to frozen (−4 °C) mesocosms of boreal forest soil and followed its decomposition. Here we show that cellulose biopolymers are hydrolyzed under frozen conditions sustaining both CO2 production and microbial growth contributing to slow, but persistent, SOM mineralization. Given the long periods with frozen soils at high latitudes these findings are essential for understanding the contribution from winter to the global carbon balance.

Place, publisher, year, edition, pages
London: Nature Publishing Group, 2017
Keywords
organic matter decomposition, unfrozen water content, freeze thaw cycles, forest soil, extracellular enzymes, exoenzyme activity, CO2 production, temperature, carbon, respiration
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-141321 (URN)10.1038/s41467-017-01230-y (DOI)000413832800009 ()
Projects
Bio4Energy
Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2019-08-30Bibliographically approved
Öquist, M. G., Erhagen, B., Haei, M., Sparrman, T., Ilstedt, U., Schleucher, J. & Nilsson, M. B. (2017). The effect of temperature and substrate quality on the carbon use efficiency of saprotrophic decomposition. Plant and Soil, 414(1), 113-125
Open this publication in new window or tab >>The effect of temperature and substrate quality on the carbon use efficiency of saprotrophic decomposition
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2017 (English)In: Plant and Soil, ISSN 0032-079X, E-ISSN 1573-5036, Vol. 414, no 1, p. 113-125Article in journal (Refereed) Published
Abstract [en]

Background and aims: Mineralization of soil organic matter (SOM) constitutes a major carbon flux to the atmosphere. The carbon use efficiency (CUE) of the saprotrophic microorganisms mineralizing SOM is integral for soil carbon dynamics. Here we investigate how the CUE is affected by temperature, metabolic conditions, and the molecular complexity of the substrate.

Methods: We incubated O-horizon soil samples (with either 13C–glucose or 13C–cellulose) from a boreal coniferous forest at 4, 9, 14, and 19 °C, and calculated CUEs based on the amount of 13C–CO2and 13C–labelled microbial biomass produced. The effects of substrate, temperature, and metabolic conditions (representing unlimited substrate supply and substrate limitation) on CUE were evaluated.

Results: CUE from metabolizing glucose was higher as compared to cellulose. A slight decrease in CUE with increasing temperature was observed in glucose amended samples (but only in the range 9–19 °C), but not in cellulose amended samples. CUE differed significantly with metabolic conditions, i.e. CUE was higher during unlimited growth conditions as compared to conditions with substrate limitation.

Conclusions: We conclude that it is integral to account for both differences in CUE during different metabolic phases, as well as complexity of substrate, when interpreting temperature dependence on CUE in incubation studies.

Keywords
Carbon use efficiency (CUE), Decomposition, Metabolic condition, NMR 13 C – substrate, Boreal forest soil
National Category
Soil Science
Identifiers
urn:nbn:se:umu:diva-129970 (URN)10.1007/s11104-016-3104-x (DOI)000399742000008 ()
Funder
Swedish Research Council, 2009-3060Swedish Research Council, 2012-2855
Available from: 2017-01-10 Created: 2017-01-10 Last updated: 2018-06-09Bibliographically approved
Wieloch, T., Ehlers, I., Frank, D., Gessler, A., Grabner, M., Yu, J. & Schleucher, J. (2017). Tree-ring cellulose exhibits several distinct intramolecular 13C signals. In: Geophysical Research Abstracts: . Paper presented at EGU General Assembly 2017. , 19, Article ID EGU2017-14723.
Open this publication in new window or tab >>Tree-ring cellulose exhibits several distinct intramolecular 13C signals
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2017 (English)In: Geophysical Research Abstracts, 2017, Vol. 19, article id EGU2017-14723Conference paper, Oral presentation with published abstract (Refereed)
National Category
Natural Sciences
Identifiers
urn:nbn:se:umu:diva-145983 (URN)
Conference
EGU General Assembly 2017
Available from: 2018-03-24 Created: 2018-03-24 Last updated: 2018-06-09
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