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Gao D, Luster J, Zürcher A, Arend M, Bai E, Gessler A, Rigling A, Schaub M, Hartmann M, Werner RA, Joseph J, Poll C, Hagedorn F. Drought resistance and resilience of rhizosphere communities in forest soils from the cellular to ecosystem scale - insights from 13C pulse labeling. THE NEW PHYTOLOGIST 2024; 242:960-974. [PMID: 38402527 DOI: 10.1111/nph.19612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 02/06/2024] [Indexed: 02/26/2024]
Abstract
The link between above- and belowground communities is a key uncertainty in drought and rewetting effects on forest carbon (C) cycle. In young beech model ecosystems and mature naturally dry pine forest exposed to 15-yr-long irrigation, we performed 13C pulse labeling experiments, one during drought and one 2 wk after rewetting, tracing tree assimilates into rhizosphere communities. The 13C pulses applied in tree crowns reached soil microbial communities of the young and mature forests one and 4 d later, respectively. Drought decreased the transfer of labeled assimilates relative to the irrigation treatment. The 13C label in phospholipid fatty acids (PLFAs) indicated greater drought reduction of assimilate incorporation by fungi (-85%) than by gram-positive (-43%) and gram-negative bacteria (-58%). 13C label incorporation was more strongly reduced for PLFAs (cell membrane) than for microbial cytoplasm extracted by chloroform. This suggests that fresh rhizodeposits are predominantly used for osmoregulation or storage under drought, at the expense of new cell formation. Two weeks after rewetting, 13C enrichment in PLFAs was greater in previously dry than in continuously moist soils. Drought and rewetting effects were greater in beech systems than in pine forest. Belowground C allocation and rhizosphere communities are highly resilient to drought.
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Affiliation(s)
- Decai Gao
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
- Qianyanzhou Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 100101, Beijing, China
- College of Resources and Environment, University of Chinese Academy of Sciences, 100190, Beijing, China
| | - Jörg Luster
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
| | - Alois Zürcher
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
| | - Matthias Arend
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
- Physiological Plant Ecology, University of Basel, 4056, Basel, Switzerland
| | - Edith Bai
- Key Laboratory of Geographical Processes and Ecological Security of Changbai Mountains, Ministry of Education, Northeast Normal University, 130024, Changchun, China
| | - Arthur Gessler
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
- Terrestrial Ecosystems, ETH Zürich, 8092, Zürich, Switzerland
| | - Andreas Rigling
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
- Terrestrial Ecosystems, ETH Zürich, 8092, Zürich, Switzerland
| | - Marcus Schaub
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
| | - Martin Hartmann
- Sustainable Agroecosystems Group, Department of Environmental Systems Science, Institute of Agricultural Sciences, ETH Zürich, 8092, Zürich, Switzerland
| | - Roland A Werner
- Agricultural Sciences, ETH Zürich, 8092, Zürich, Switzerland
| | - Jobin Joseph
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
| | - Christian Poll
- Soil Biology, University of Hohenheim, 70599, Stuttgart, Germany
| | - Frank Hagedorn
- Swiss Federal Institute for Forest, Snow and Landscape Research, 8903, Birmensdorf, Switzerland
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Yao Y, Xia L, Yang L, Liu R, Zhang S. Drought responses and carbon allocation strategies of poplar with different leaf maturity. PHYSIOLOGIA PLANTARUM 2024; 176:e14224. [PMID: 38389291 DOI: 10.1111/ppl.14224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 02/08/2024] [Indexed: 02/24/2024]
Abstract
Leaf characteristics can reflect the adaptation of trees to drought stress. However, the effect of leaf maturity on drought stress has been neglected, leading to uncertainty in inferring individual tree responses to drought from leaves. The allocation strategy of photosynthetic carbon between leaf organs (fully expanded young and old leaves) under drought stress remains unclear. Poplar is a diverse and widespread tree species in arid and semi-arid regions. Here, three poplar genotypes (Populus cathayana, P. × euramericana 'Nanlin 895', and P. alba × P. tremula var. glandulosa) were selected and exposed to different watering regimes. The responses and carbon allocation strategies of leaves with different maturity to drought were investigated using a combination of leaf traits and 13 C pulse labelling technique. The results showed that (1) fully expanded young leaves had better osmotic regulation and antioxidant capacity than aged leaves under drought stress. (2) Aged leaves acted as a carbon source during water deficit, where their photosynthetic products were transferred and supplied to upper young leaves to promote stronger photosynthesis in young leaves to acquire resources for tree growth. This study highlights that the effect of leaf maturity should be considered in the future when investigating the effects of drought on woody plants, especially for continuously growing tree species. Therefore, our study not only demonstrates the existence of leaf-age-dependent responses to drought in poplar but also provides new insights into carbon allocation at the leaf level.
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Affiliation(s)
- Yuan Yao
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Linchao Xia
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Le Yang
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Ruixuan Liu
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Sheng Zhang
- Key Laboratory for Bio-resource and Eco-environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
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Meeran K, Verbrigghe N, Ingrisch J, Fuchslueger L, Müller L, Sigurðsson P, Sigurdsson BD, Wachter H, Watzka M, Soong JL, Vicca S, Janssens IA, Bahn M. Individual and interactive effects of warming and nitrogen supply on CO 2 fluxes and carbon allocation in subarctic grassland. GLOBAL CHANGE BIOLOGY 2023; 29:5276-5291. [PMID: 37427494 PMCID: PMC10962691 DOI: 10.1111/gcb.16851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 05/21/2023] [Indexed: 07/11/2023]
Abstract
Climate warming has been suggested to impact high latitude grasslands severely, potentially causing considerable carbon (C) losses from soil. Warming can also stimulate nitrogen (N) turnover, but it is largely unclear whether and how altered N availability impacts belowground C dynamics. Even less is known about the individual and interactive effects of warming and N availability on the fate of recently photosynthesized C in soil. On a 10-year geothermal warming gradient in Iceland, we studied the effects of soil warming and N addition on CO2 fluxes and the fate of recently photosynthesized C through CO2 flux measurements and a 13 CO2 pulse-labeling experiment. Under warming, ecosystem respiration exceeded maximum gross primary productivity, causing increased net CO2 emissions. N addition treatments revealed that, surprisingly, the plants in the warmed soil were N limited, which constrained primary productivity and decreased recently assimilated C in shoots and roots. In soil, microbes were increasingly C limited under warming and increased microbial uptake of recent C. Soil respiration was increased by warming and was fueled by increased belowground inputs and turnover of recently photosynthesized C. Our findings suggest that a decade of warming seemed to have induced a N limitation in plants and a C limitation by soil microbes. This caused a decrease in net ecosystem CO2 uptake and accelerated the respiratory release of photosynthesized C, which decreased the C sequestration potential of the grassland. Our study highlights the importance of belowground C allocation and C-N interactions in the C dynamics of subarctic ecosystems in a warmer world.
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Affiliation(s)
| | - Niel Verbrigghe
- Research Group Plants and EcosystemsUniversity of AntwerpAntwerpBelgium
| | | | - Lucia Fuchslueger
- Research Group Plants and EcosystemsUniversity of AntwerpAntwerpBelgium
- Centre for Microbiology and Environmental Systems ScienceUniversity of ViennaViennaAustria
| | - Lena Müller
- Department of EcologyUniversity of InnsbruckInnsbruckAustria
| | | | | | - Herbert Wachter
- Department of EcologyUniversity of InnsbruckInnsbruckAustria
| | - Margarete Watzka
- Centre for Microbiology and Environmental Systems ScienceUniversity of ViennaViennaAustria
| | - Jennifer L. Soong
- Research Group Plants and EcosystemsUniversity of AntwerpAntwerpBelgium
- Soil and Crop Sciences DepartmentColorado State UniversityFort CollinsColoradoUSA
| | - Sara Vicca
- Research Group Plants and EcosystemsUniversity of AntwerpAntwerpBelgium
| | - Ivan A. Janssens
- Research Group Plants and EcosystemsUniversity of AntwerpAntwerpBelgium
| | - Michael Bahn
- Department of EcologyUniversity of InnsbruckInnsbruckAustria
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Tixier A, Forest M, Prudent M, Durey V, Zwieniecki M, Barnard RL. Root exudation of carbon and nitrogen compounds varies over the day-night cycle in pea: The role of diurnal changes in internal pools. PLANT, CELL & ENVIRONMENT 2023; 46:962-974. [PMID: 36562125 DOI: 10.1111/pce.14523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 12/13/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Abstract
Rhizodeposition is the export of organic compounds from plant roots to the soil. Carbon allocation towards rhizodeposition has to be balanced with allocation for other physiological functions, which depend on both newly assimilated and stored nonstructural carbohydrate (NSC). To test whether the exudation of primary metabolites scales with plant NSC status, we studied diurnal dynamics of NSC and amino acid (AA) pools and fluxes within the plant and the rhizosphere. These diurnal dynamics were measured in the field and under hydroponic-controlled conditions. Further, C-limiting treatments offered further insight into the regulation of rhizodeposition. The exudation of primary metabolites fluctuated diurnally. The diurnal dynamics of soluble sugars (SS) and AA concentrations in tissues coincided with exudate pool fluctuations in the rhizosphere. SS and AA pools in the rhizosphere increased with NSC and AA pools in the roots. C starvation treatments offset the balance of exudates: AA exudate content in the rhizosphere significantly decreased while SS exudate content remained stable. Our results suggest that rhizodeposition is to some extent controlled by plant C:N status. We propose that SS exudation is less controlled than AA exudation because N assimilation depends on controlled C supply while SS exudation relies to a greater extent on passive diffusion mechanisms.
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Affiliation(s)
- Aude Tixier
- Agroécologie, AgroSup Dijon, INRAE, Université de Bourgogne, Université Bourgogne Franche-Comté, Dijon, France
| | - Marion Forest
- Agroécologie, AgroSup Dijon, INRAE, Université de Bourgogne, Université Bourgogne Franche-Comté, Dijon, France
| | - Marion Prudent
- Agroécologie, AgroSup Dijon, INRAE, Université de Bourgogne, Université Bourgogne Franche-Comté, Dijon, France
| | - Vincent Durey
- Agroécologie, AgroSup Dijon, INRAE, Université de Bourgogne, Université Bourgogne Franche-Comté, Dijon, France
| | - Maciej Zwieniecki
- Department of Plant Sciences, University of California, Davis, California, USA
| | - Romain L Barnard
- Agroécologie, AgroSup Dijon, INRAE, Université de Bourgogne, Université Bourgogne Franche-Comté, Dijon, France
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5
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Dodd RJ, Chadwick DR, Hill PW, Hayes F, Sánchez-Rodríguez AR, Gwynn-Jones D, Smart SM, Jones DL. Resilience of ecosystem service delivery in grasslands in response to single and compound extreme weather events. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 861:160660. [PMID: 36464051 DOI: 10.1016/j.scitotenv.2022.160660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Revised: 11/29/2022] [Accepted: 11/29/2022] [Indexed: 06/17/2023]
Abstract
Extreme weather events are increasing in frequency and magnitude with profound effects on ecosystem functioning. Further, there is now a greater likelihood that multiple extreme events are occurring within a single year. Here we investigated the effect of a single drought, flood or compound (flood + drought) extreme event on temperate grassland ecosystem processes in a field experiment. To assess system resistance and resilience, we studied changes in a wide range of above- and below-ground indicators (plant diversity and productivity, greenhouse gas emissions, soil chemical, physical and biological metrics) during the 8 week stress events and then for 2 years post-stress. We hypothesized that agricultural grasslands would have different degrees of resistance and resilience to flood and drought stress. We also investigated two alternative hypotheses that the combined flood + drought treatment would either, (A) promote ecosystem resilience through more rapid recovery of soil moisture conditions or (B) exacerbate the impact of the single flood or drought event. Our results showed that flooding had a much greater effect than drought on ecosystem processes and that the grassland was more resistant and resilient to drought than to flood. The immediate impact of flooding on all indicators was negative, especially for those related to production, and climate and water regulation. Flooding stress caused pronounced and persistent shifts in soil microbial and plant communities with large implications for nutrient cycling and long-term ecosystem function. The compound flood + drought treatment failed to show a more severe impact than the single extreme events. Rather, there was an indication of quicker recovery of soil and microbial parameters suggesting greater resilience in line with hypothesis (A). This study clearly reveals that contrasting extreme weather events differentially affect grassland ecosystem function but that concurrent events of a contrasting nature may promote ecosystem resilience to future stress.
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Affiliation(s)
- Rosalind J Dodd
- UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Ave, Bailrigg LA1 4AP, UK; Environment Centre Wales, School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK.
| | - David R Chadwick
- Environment Centre Wales, School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK
| | - Paul W Hill
- Environment Centre Wales, School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK
| | - Felicity Hayes
- UK Centre for Ecology and Hydrology, Environment Centre Wales, Bangor, Gwynedd LL57 2UW, UK
| | - Antonio R Sánchez-Rodríguez
- Environment Centre Wales, School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK; Departamento de Agronomía, Universidad de Córdoba, Córdoba 14071, Spain
| | - Dylan Gwynn-Jones
- Department of Life Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3DA, UK
| | - Simon M Smart
- UK Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Ave, Bailrigg LA1 4AP, UK
| | - Davey L Jones
- Environment Centre Wales, School of Natural Sciences, Bangor University, Bangor, Gwynedd LL57 2UW, UK; SoilsWest, Centre for Sustainable Farming Systems, Food Futures Institute, Murdoch University, Murdoch, WA 6105, Australia
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6
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Ulrich DEM, Clendinen CS, Alongi F, Mueller RC, Chu RK, Toyoda J, Gallegos-Graves LV, Goemann HM, Peyton B, Sevanto S, Dunbar J. Root exudate composition reflects drought severity gradient in blue grama (Bouteloua gracilis). Sci Rep 2022; 12:12581. [PMID: 35869127 PMCID: PMC9307599 DOI: 10.1038/s41598-022-16408-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 07/11/2022] [Indexed: 12/22/2022] Open
Abstract
Plant survival during environmental stress greatly affects ecosystem carbon (C) cycling, and plant–microbe interactions are central to plant stress survival. The release of C-rich root exudates is a key mechanism plants use to manage their microbiome, attracting beneficial microbes and/or suppressing harmful microbes to help plants withstand environmental stress. However, a critical knowledge gap is how plants alter root exudate concentration and composition under varying stress levels. In a greenhouse study, we imposed three drought treatments (control, mild, severe) on blue grama (Bouteloua gracilis Kunth Lag. Ex Griffiths), and measured plant physiology and root exudate concentration and composition using GC–MS, NMR, and FTICR. With increasing drought severity, root exudate total C and organic C increased concurrently with declining predawn leaf water potential and photosynthesis. Root exudate composition mirrored the physiological gradient of drought severity treatments. Specific compounds that are known to alter plant drought responses and the rhizosphere microbiome mirrored the drought severity-induced root exudate compositional gradient. Despite reducing C uptake, these plants actively invested C to root exudates with increasing drought severity. Patterns of plant physiology and root exudate concentration and composition co-varied along a gradient of drought severity.
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Cong Y, Saurer M, Bai E, Siegwolf R, Gessler A, Liu K, Han H, Dang Y, Xu W, He HS, Li MH. In situ 13CO2 labeling reveals that alpine treeline trees allocate less photoassimilates to roots compared with low-elevation trees. TREE PHYSIOLOGY 2022; 42:1943-1956. [PMID: 35535565 DOI: 10.1093/treephys/tpac048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 04/13/2022] [Indexed: 06/14/2023]
Abstract
Carbon (C) allocation plays a crucial role for survival and growth of alpine treeline trees, however it is still poorly understood. Using in situ 13CO2 labeling, we investigated the leaf photosynthesis and the allocation of 13C labeled photoassimilates in various tissues (leaves, twigs and fine roots) in treeline trees and low-elevation trees. Non-structural carbohydrate concentrations were also determined. The alpine treeline trees (2000 m. a.s.l.), compared with low-elevation trees (1700 m a.s.l.), did not show any disadvantage in photosynthesis, but the former allocated proportionally less newly assimilated C belowground than the latter. Carbon residence time in leaves was longer in treeline trees (19 days) than that in low-elevation ones (10 days). We found an overall lower density of newly assimilated C in treeline trees. The alpine treeline trees may have a photosynthetic compensatory mechanism to counteract the negative effects of the harsh treeline environment (e.g., lower temperature and shorter growing season) on C gain. Lower temperature at treeline may limit the sink activity and C downward transport via phloem, and shorter treeline growing season may result in early cessation of root growth, decreases sink strength, which all together lead to lower density of new C in the sink tissues and finally limit the growth of the alpine treeline trees.
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Affiliation(s)
- Yu Cong
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
- Northeast Institute of Geography and Agricultural Ecology, Chinese Academy of Sciences, 4888 Shengbei Street, Kuancheng District, Changchun 130102, China
| | - Matthias Saurer
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse111, Birmensdorf CH-8903, Switzerland
| | - Edith Bai
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
| | - Rolf Siegwolf
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse111, Birmensdorf CH-8903, Switzerland
| | - Arthur Gessler
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse111, Birmensdorf CH-8903, Switzerland
- Institute of Terrestrial Ecosystems, ETH Zurich, Universitaetsstrasse 16, Zurich 8092, Switzerland
| | - Kai Liu
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
| | - Hudong Han
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
| | - Yongcai Dang
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
| | - Wenhua Xu
- Institute of Agricultural Resource and Environment, Jilin Academy of Agricultural Sciences, 1363 Shengtai Street, Nanguan District, Changchun 130033, China
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, 72 Wenhua Road, Shenhe District, Shenyang 110016, China
| | - Hong S He
- School of Natural Resources, University of Missouri, Columbia, MO 65211, USA
| | - Mai-He Li
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, 5268 Renmin Street, Nanguan District, Changchun 130024, China
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse111, Birmensdorf CH-8903, Switzerland
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Below-Ground Growth of Alpine Plants, Not Above-Ground Growth, Is Linked to the Extent of Its Carbon Storage. PLANTS 2021; 10:plants10122680. [PMID: 34961151 PMCID: PMC8705842 DOI: 10.3390/plants10122680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 11/20/2021] [Accepted: 12/03/2021] [Indexed: 11/16/2022]
Abstract
Understanding carbon allocation in plants is essential for explaining their growth strategies during environmental adaptation. However, the role of mobile carbon in plant growth and its response to habitat conditions is still disputed. In degraded meadow (alpine sandy grassland) and non-degraded meadow (typical alpine meadow and swamp meadow) on the Qinghai–Tibetan Plateau, we measured the monthly averages of above-ground biomass (AGB) and below-ground biomass (BGB) of the investigated species in each meadow and the average concentration of non-structural carbohydrates (NSCs), an indicator of carbon storage. Below-ground organs had higher concentrations and showed more seasonal variation in NSCs than above-ground organs. BGB had a positive correlation with below-ground NSCs levels. However, AGB had no clear relationship with above-ground NSCs levels. Plants in sandy grasslands had higher total NSC, soluble sugars, fructose, and sucrose concentrations and lower starch concentrations in below-ground organs than plants in alpine or swamp meadows. Overall, NSCs storage, particularly soluble sugars, is a major process underlying the pattern of below-ground growth, but not above-ground growth, in the meadow ecosystem of the Qinghai–Tibetan Plateau, and degraded meadow strengthens this process. These results suggest that the extent of carbon storage in non-photosynthetic organs of alpine herbs impacts their growth and habitat adaptation.
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Meeran K, Ingrisch J, Reinthaler D, Canarini A, Müller L, Pötsch EM, Richter A, Wanek W, Bahn M. Warming and elevated CO 2 intensify drought and recovery responses of grassland carbon allocation to soil respiration. GLOBAL CHANGE BIOLOGY 2021; 27:3230-3243. [PMID: 33811716 DOI: 10.1111/gcb.15628] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 03/07/2021] [Accepted: 03/15/2021] [Indexed: 05/26/2023]
Abstract
Photosynthesis and soil respiration represent the two largest fluxes of CO2 in terrestrial ecosystems and are tightly linked through belowground carbon (C) allocation. Drought has been suggested to impact the allocation of recently assimilated C to soil respiration; however, it is largely unknown how drought effects are altered by a future warmer climate under elevated atmospheric CO2 (eT_eCO2 ). In a multifactor experiment on managed C3 grassland, we studied the individual and interactive effects of drought and eT_eCO2 (drought, eT_eCO2 , drought × eT_eCO2 ) on ecosystem C dynamics. We performed two in situ 13 CO2 pulse-labeling campaigns to trace the fate of recent C during peak drought and recovery. eT_eCO2 increased soil respiration and the fraction of recently assimilated C in soil respiration. During drought, plant C uptake was reduced by c. 50% in both ambient and eT_eCO2 conditions. Soil respiration and the amount and proportion of 13 C respired from soil were reduced (by 32%, 70% and 30%, respectively), the effect being more pronounced under eT_eCO2 (50%, 84%, 70%). Under drought, the diel coupling of photosynthesis and SR persisted only in the eT_eCO2 scenario, likely caused by dynamic shifts in the use of freshly assimilated C between storage and respiration. Drought did not affect the fraction of recent C remaining in plant biomass under ambient and eT_eCO2 , but reduced the small fraction remaining in soil under eT_eCO2 . After rewetting, C uptake and the proportion of recent C in soil respiration recovered more rapidly under eT_eCO2 compared to ambient conditions. Overall, our findings suggest that in a warmer climate under elevated CO2 drought effects on the fate of recent C will be amplified and the coupling of photosynthesis and soil respiration will be sustained. To predict the future dynamics of terrestrial C cycling, such interactive effects of multiple global change factors should be considered.
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Affiliation(s)
| | | | - David Reinthaler
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Alberto Canarini
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Lena Müller
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Erich M Pötsch
- Institute of Plant Production and Cultural Landscape, Agricultural Research and Education Centre, Raumberg-Gumpenstein, Austria
| | - Andreas Richter
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Wolfgang Wanek
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Michael Bahn
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
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Guo T, Tian C, Chen C, Duan Z, Zhu Q, Sun LZ. Growth and carbohydrate dynamic of perennial ryegrass seedlings during PEG-simulated drought and subsequent recovery. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 154:85-93. [PMID: 32535324 DOI: 10.1016/j.plaphy.2020.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/01/2020] [Accepted: 06/03/2020] [Indexed: 06/11/2023]
Abstract
Due to the increasing occurrence of drought events, drought recovery has become equally important as drought resistance for long-term growth and survival of plants. However, information regarding the mechanism that controls growth recovery of herbaceous perennials is not available. In this study, perennial ryegrass (Lolium perenne) was rewatered after eight-day exposure to three drought intensities simulated by polyethylene glycol-6000. The growth, nonstructural carbohydrates (NSC, i.e. sucrose, glucose, fructose and starch), shoot δ13C, and activities of enzymes for sucrose conversion were monitored for 24 days after rewatering, allowing investigation of the dynamic of NSCs and its relation with growth in the recovery phase. In response to drought, growth and NSC content decreased mainly in shoot rather than root, and the total dry matter was negatively correlated to shoot δ13C. After rewatering, the growth of drought-treated groups still lagged behind that of control (CK) group for more than 16 days, but it was no longer correlated to shoot δ13C, suggesting that the limited growth is caused by non-stomatal factors related to photosynthesis. On day 24 after rewatering, the final growth of drought-treated groups caught up or even exceeded that of CK group, and was accompanied by higher dry weight root to shoot ratio (R/S) and root NSC content, which may facilitate water and nutrient acquisition and emergency of new tillers, respectively. During drought and subsequent recovery, the variation of R/S and root NSC content mainly attributed to root acid invertase rather than leaf sucrose phosphate synthase activity.
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Affiliation(s)
- Tongtian Guo
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Chen Tian
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Chunyan Chen
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Zhaoyang Duan
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Qi Zhu
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Luan Zi Sun
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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Ingrisch J, Karlowsky S, Hasibeder R, Gleixner G, Bahn M. Drought and recovery effects on belowground respiration dynamics and the partitioning of recent carbon in managed and abandoned grassland. GLOBAL CHANGE BIOLOGY 2020; 26:4366-4378. [PMID: 32343042 PMCID: PMC7384171 DOI: 10.1111/gcb.15131] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 04/09/2020] [Indexed: 05/23/2023]
Abstract
The supply of soil respiration with recent photoassimilates is an important and fast pathway for respiratory loss of carbon (C). To date it is unknown how drought and land-use change interactively influence the dynamics of recent C in soil-respired CO2 . In an in situ common-garden experiment, we exposed soil-vegetation monoliths from a managed and a nearby abandoned mountain grassland to an experimental drought. Based on two 13 CO2 pulse-labelling campaigns, we traced recently assimilated C in soil respiration during drought, rewetting and early recovery. Independent of grassland management, drought reduced the absolute allocation of recent C to soil respiration. Rewetting triggered a respiration pulse, which was strongly fuelled by C assimilated during drought. In comparison to the managed grassland, the abandoned grassland partitioned more recent C to belowground respiration than to root C storage under ample water supply. Interestingly, this pattern was reversed under drought. We suggest that these different response patterns reflect strategies of the managed and the abandoned grassland to enhance their respective resilience to drought, by fostering their resistance and recovery respectively. We conclude that while severe drought can override the effects of abandonment of grassland management on the respiratory dynamics of recent C, abandonment alters strategies of belowground assimilate investment, with consequences for soil-CO2 fluxes during drought and drought-recovery.
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Affiliation(s)
| | - Stefan Karlowsky
- Max Planck Institute for BiogeochemistryJenaGermany
- Leibniz‐Institute of Vegetable and Ornamental CropsGroßbeerenGermany
| | | | | | - Michael Bahn
- Department of EcologyUniversity of InnsbruckInnsbruckAustria
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12
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Hartmann H, Bahn M, Carbone M, Richardson AD. Plant carbon allocation in a changing world - challenges and progress: introduction to a Virtual Issue on carbon allocation: Introduction to a virtual issue on carbon allocation. THE NEW PHYTOLOGIST 2020; 227:981-988. [PMID: 32662104 DOI: 10.1111/nph.16757] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Affiliation(s)
- Henrik Hartmann
- Department of Biogeochemical Processes, Max Planck Institute for Biogeochemistry, Hans Knoll Str. 10, 07745, Jena, Germany
| | - Michael Bahn
- Department of Ecology, University of Innsbruck, Sternwartestraße 15, 6020, Innsbruck, Austria
| | - Mariah Carbone
- Department of Biological Sciences, Center for Ecosystem Science and Society, Northern Arizona University, 200 Beckwith Way, Flagstaff, AZ, 86011, USA
| | - Andrew D Richardson
- Department of Biological Sciences, Center for Ecosystem Science and Society, Northern Arizona University, 200 Beckwith Way, Flagstaff, AZ, 86011, USA
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13
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Plant growth drives soil nitrogen cycling and N-related microbial activity through changing root traits. FUNGAL ECOL 2020. [DOI: 10.1016/j.funeco.2019.100910] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Möhl P, Hiltbrunner E, Körner C. Halving sunlight reveals no carbon limitation of aboveground biomass production in alpine grassland. GLOBAL CHANGE BIOLOGY 2020; 26:1857-1872. [PMID: 31799736 DOI: 10.1111/gcb.14949] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 11/21/2019] [Accepted: 11/26/2019] [Indexed: 05/24/2023]
Abstract
In temperate alpine environments, the short growing season, low temperature and a slow nutrient cycle may restrict plant growth more than carbon (C) assimilation does. To test whether C is a limiting resource, we applied a shade gradient from ambient light to 44% (maximum shade) of incident photon flux density (PFD) in late successional, Carex curvula-dominated alpine grassland at 2,580 m elevation in the Swiss central Alps for 3 years (2014-2016). Total aboveground biomass did not significantly decrease under reduced PFD, with a confidence interval ranging from +4% to -15% biomass in maximum shade. Belowground biomass, of which more than 80% were fine roots, was significantly reduced by a mean of 17.9 ± 4.6% (±SE), corresponding to 228 g/m2 , in maximum shade in 2015 and 2016. This suggests reduced investments into water and nutrient acquisition according to the functional equilibrium concept. Specific leaf area (SLA) and maximum leaf length of the most abundant species increased with decreasing PFD. Foliar concentration of nonstructural carbohydrates (NSC) was reduced by 12.5 ± 4.3% under maximum shade (mean of eight tested species), while NSC concentration of belowground storage organs were unchanged in the four most abundant forbs. Furthermore, maximum shade lowered foliar δ13 C by 1.56 ± 0.35‰ and increased foliar nitrogen concentrations per unit dry mass by 18.8 ± 4.1% across six species in 2015. However, based on unit leaf area, N concentrations were lower in shade (effect of higher SLA). Thus, while we found typical morphological and physiological plant responses to lower light, shading did not considerably affect seasonal aboveground biomass production of this alpine plant community within a broad range of PFD. This suggests that C is not a growth-limiting resource, matching the unresponsiveness to in situ CO2 enrichment previously reported for this type of grassland.
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Affiliation(s)
- Patrick Möhl
- Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Erika Hiltbrunner
- Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Christian Körner
- Department of Environmental Sciences, University of Basel, Basel, Switzerland
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15
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16
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Karlowsky S, Augusti A, Ingrisch J, Akanda MKU, Bahn M, Gleixner G. Drought-Induced Accumulation of Root Exudates Supports Post-drought Recovery of Microbes in Mountain Grassland. FRONTIERS IN PLANT SCIENCE 2018; 9:1593. [PMID: 30464767 PMCID: PMC6234839 DOI: 10.3389/fpls.2018.01593] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 10/15/2018] [Indexed: 05/28/2023]
Abstract
Droughts strongly affect carbon and nitrogen cycling in grasslands, with consequences for ecosystem productivity. Therefore, we investigated how experimental grassland communities interact with groups of soil microorganisms. In particular, we explored the mechanisms of the drought-induced decoupling of plant photosynthesis and microbial carbon cycling and its recovery after rewetting. Our aim was to better understand how root exudation during drought is linked to pulses of soil microbial activity and changes in plant nitrogen uptake after rewetting. We set up a mesocosm experiment on a meadow site and used shelters to simulate drought. We performed two 13C-CO2 pulse labelings, the first at peak drought and the second in the recovery phase, and traced the flow of assimilates into the carbohydrates of plants and the water extractable organic carbon and microorganisms from the soil. Total microbial tracer uptake in the main metabolism was estimated by chloroform fumigation extraction, whereas the lipid biomarkers were used to assess differences between the microbial groups. Drought led to a reduction of aboveground versus belowground plant growth and to an increase of 13C tracer contents in the carbohydrates, particularly in the roots. Newly assimilated 13C tracer unexpectedly accumulated in the water-extractable soil organic carbon, indicating that root exudation continued during the drought. In contrast, drought strongly reduced the amount of 13C tracer assimilated into the soil microorganisms. This reduction was more severe in the growth-related lipid biomarkers than in the metabolic compounds, suggesting a slowdown of microbial processes at peak drought. Shortly after rewetting, the tracer accumulation in the belowground plant carbohydrates and in the water-extractable soil organic carbon disappeared. Interestingly, this disappearance was paralleled by a quick recovery of the carbon uptake into metabolic and growth-related compounds from the rhizospheric microorganisms, which was probably related to the higher nitrogen supply to the plant shoots. We conclude that the decoupling of plant photosynthesis and soil microbial carbon cycling during drought is due to reduced carbon uptake and metabolic turnover of rhizospheric soil microorganisms. Moreover, our study suggests that the maintenance of root exudation during drought is connected to a fast reinitiation of soil microbial activity after rewetting, supporting plant recovery through increased nitrogen availability.
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Affiliation(s)
| | - Angela Augusti
- Research Institute on Terrestrial Ecosystems, Consiglio Nazionale delle Ricerche, Rome, Italy
| | | | | | - Michael Bahn
- Institute of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Gerd Gleixner
- Max Planck Institute for Biogeochemistry, Jena, Germany
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Karlowsky S, Augusti A, Ingrisch J, Hasibeder R, Lange M, Lavorel S, Bahn M, Gleixner G, Wurzburger N. Land use in mountain grasslands alters drought response and recovery of carbon allocation and plant-microbial interactions. THE JOURNAL OF ECOLOGY 2018; 106:1230-1243. [PMID: 29780173 PMCID: PMC5947120 DOI: 10.1111/1365-2745.12910] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 10/19/2017] [Indexed: 05/07/2023]
Abstract
Mountain grasslands have recently been exposed to substantial changes in land use and climate and in the near future will likely face an increased frequency of extreme droughts. To date, how the drought responses of carbon (C) allocation, a key process in the C cycle, are affected by land-use changes in mountain grassland is not known.We performed an experimental summer drought on an abandoned grassland and a traditionally managed hay meadow and traced the fate of recent assimilates through the plant-soil continuum. We applied two 13 CO 2 pulses, at peak drought and in the recovery phase shortly after rewetting.Drought decreased total C uptake in both grassland types and led to a loss of above-ground carbohydrate storage pools. The below-ground C allocation to root sucrose was enhanced by drought, especially in the meadow, which also held larger root carbohydrate storage pools.The microbial community of the abandoned grassland comprised more saprotrophic fungal and Gram(+) bacterial markers compared to the meadow. Drought increased the newly introduced AM and saprotrophic (A+S) fungi:bacteria ratio in both grassland types. At peak drought, the 13C transfer into AM and saprotrophic fungi, and Gram(-) bacteria was more strongly reduced in the meadow than in the abandoned grassland, which contrasted the patterns of the root carbohydrate pools.In both grassland types, the C allocation largely recovered after rewetting. Slowest recovery was found for AM fungi and their 13C uptake. In contrast, all bacterial markers quickly recovered C uptake. In the meadow, where plant nitrate uptake was enhanced after drought, C uptake was even higher than in control plots. Synthesis. Our results suggest that resistance and resilience (i.e. recovery) of plant C dynamics and plant-microbial interactions are negatively related, that is, high resistance is followed by slow recovery and vice versa. The abandoned grassland was more resistant to drought than the meadow and possibly had a stronger link to AM fungi that could have provided better access to water through the hyphal network. In contrast, meadow communities strongly reduced C allocation to storage and C transfer to the microbial community in the drought phase, but in the recovery phase invested C resources in the bacterial communities to gain more nutrients for regrowth. We conclude that the management of mountain grasslands increases their resilience to drought.
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Affiliation(s)
| | - Angela Augusti
- Institute of Agro‐Environmental and Forest BiologyCNR ItalyPorano (TR)Italy
| | | | | | - Markus Lange
- Max Planck Institute for BiogeochemistryJenaGermany
| | - Sandra Lavorel
- Laboratoire d'Ecologie AlpineUMR 5553 CNRSUniversité Joseph FourierGrenoble Cedex 9France
| | - Michael Bahn
- Institute of EcologyUniversity of InnsbruckInnsbruckAustria
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18
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Srivastava K, Jentsch A, Kreyling J, Glaser B, Wiesenberg GLB. Short-term carbon dynamics in a temperate grassland and heathland ecosystem exposed to 104 days of drought followed by irrigation. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2018; 54:41-62. [PMID: 28914091 DOI: 10.1080/10256016.2017.1371714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 07/13/2017] [Indexed: 06/07/2023]
Abstract
Temperate ecosystems are susceptible to drought events. The effect of a severe drought (104 days) followed by irrigation on the plant C uptake, its assimilation and input of C in soil were examined using a triple 13CO2 pulse-chase labelling experiment in model grassland and heathland ecosystems. First 13CO2 pulse at day 0 of the experiment revealed much higher 13C tracer uptake for shoots, roots and soil compared to the second pulse (day 44), where all plants showed significantly lower 13C tracer uptake. After the third 13CO2 pulse (day 70), very low 13C uptake in shoots led to a negligible allocation of 13C into roots and soil. During irrigation after the severe drought, the 13C tracer that was allocated in plant tissues during the second and third pulse labelling was re-allocated in roots and soil, as soon as the irrigation started. This re-allocation was higher and longer lasting in heathland compared to grassland ecosystems.
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Affiliation(s)
- Kavita Srivastava
- a Department of Geography , University of Zurich , Zurich , Switzerland
- b Department of Disturbance Ecology , University of Bayreuth , Bayreuth , Germany
| | - Anke Jentsch
- b Department of Disturbance Ecology , University of Bayreuth , Bayreuth , Germany
| | - Juergen Kreyling
- c Experimental Plant Ecology, Institute of Botany and Landscape Ecology , University of Greifswald , Greifswald , Germany
| | - Bruno Glaser
- d Department of Soil Biogeochemistry , Martin Luther University Halle-Wittenberg , Halle , Germany
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Sarker JR, Singh BP, He X, Fang Y, Li GD, Collins D, Cowie AL. Tillage and nitrogen fertilization enhanced belowground carbon allocation and plant nitrogen uptake in a semi-arid canola crop-soil system. Sci Rep 2017; 7:10726. [PMID: 28878351 PMCID: PMC5587530 DOI: 10.1038/s41598-017-11190-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 08/16/2017] [Indexed: 12/04/2022] Open
Abstract
Carbon (C) and nitrogen (N) allocation and assimilation are coupled processes, likely influencing C accumulation, N use efficiency and plant productivity in agro-ecosystems. However, dynamics and responses of these processes to management practices in semi-arid agro-ecosystems are poorly understood. A field-based 13CO2 and urea-15N pulse labelling experiment was conducted to track how C and N allocation and assimilation during canola growth from flowering to maturity were affected by short-term (2-year) tillage (T) and no-till (NT) with or without 100 kg urea-N ha-1 (T-0, T-100, NT-0, NT-100) on a Luvisol in an Australian semi-arid region. The T-100 caused greater (P < 0.05) belowground C allocation and higher (P < 0.05) translocation of soil N to shoots and seeds, compared to other treatments. Microbial N uptake was rapid and greatest in the fertilized (cf. non-fertilized) treatments, followed by a rapid release of microbial immobilized N, thus increasing N availability for plant uptake. In contrast, management practices had insignificant impact on soil C and N stocks, aggregate stability, microbial biomass, and 13C retention in aggregate-size fractions. In conclusion, tillage and N fertilization increased belowground C allocation and crop N uptake and yield, possibly via enhancing root-microbial interactions, with minimal impact on soil properties.
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Affiliation(s)
- Jharna Rani Sarker
- University of New England, Armidale, NSW 2351, Australia
- NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Woodbridge Road, Menangle, NSW 2568, Australia
| | - Bhupinder Pal Singh
- University of New England, Armidale, NSW 2351, Australia.
- NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Woodbridge Road, Menangle, NSW 2568, Australia.
| | - Xinhua He
- NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Woodbridge Road, Menangle, NSW 2568, Australia
- College of Resources and Environment, Southwest University, Chongqing, 400715, China
| | - Yunying Fang
- NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Woodbridge Road, Menangle, NSW 2568, Australia
| | - Guangdi D Li
- NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650, Australia
| | - Damian Collins
- NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Woodbridge Road, Menangle, NSW 2568, Australia
| | - Annette L Cowie
- University of New England, Armidale, NSW 2351, Australia
- NSW Department of Primary Industries, Beef Industry Centre, Trevenna Road, Armidale, NSW 2351, Australia
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Gavazov K, Ingrisch J, Hasibeder R, Mills RTE, Buttler A, Gleixner G, Pumpanen J, Bahn M. Winter ecology of a subalpine grassland: Effects of snow removal on soil respiration, microbial structure and function. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 590-591:316-324. [PMID: 28279534 DOI: 10.1016/j.scitotenv.2017.03.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/08/2017] [Accepted: 03/02/2017] [Indexed: 06/06/2023]
Abstract
Seasonal snow cover provides essential insulation for mountain ecosystems, but expected changes in precipitation patterns and snow cover duration due to global warming can influence the activity of soil microbial communities. In turn, these changes have the potential to create new dynamics of soil organic matter cycling. To assess the effects of experimental snow removal and advanced spring conditions on soil carbon (C) and nitrogen (N) dynamics, and on the biomass and structure of soil microbial communities, we performed an in situ study in a subalpine grassland in the Austrian Alps, in conjunction with soil incubations under controlled conditions. We found substantial winter C-mineralisation and high accumulation of inorganic and organic N in the topsoil, peaking at snowmelt. Soil microbial biomass doubled under the snow, paralleled by a fivefold increase in its C:N ratio, but no apparent change in its bacteria-dominated community structure. Snow removal led to a series of mild freeze-thaw cycles, which had minor effects on in situ soil CO2 production and N mineralisation. Incubated soil under advanced spring conditions, however, revealed an impaired microbial metabolism shortly after snow removal, characterised by a limited capacity for C-mineralisation of both fresh plant-derived substrates and existing soil organic matter (SOM), leading to reduced priming effects. This effect was transient and the observed recovery in microbial respiration and SOM priming towards the end of the winter season indicated microbial resilience to short-lived freeze-thaw disturbance under field conditions. Bacteria showed a higher potential for uptake of plant-derived C substrates during this recovery phase. The observed temporary loss in microbial C-mineralisation capacity and the promotion of bacteria over fungi can likely impede winter SOM cycling in mountain grasslands under recurrent winter climate change events, with plausible implications for soil nutrient availability and plant-soil interactions.
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Affiliation(s)
- Konstantin Gavazov
- Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 98107 Abisko, Sweden.
| | - Johannes Ingrisch
- Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
| | - Roland Hasibeder
- Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
| | - Robert T E Mills
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, United Kingdom
| | - Alexandre Buttler
- Ecole Polytechnique Fédérale de Lausanne EPFL, School of Architecture, Civil and Environmental Engineering ENAC, Laboratory of Ecological Systems ECOS, Station 2, 1015 Lausanne, Switzerland; Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Site Lausanne, Station 2, 1015 Lausanne, Switzerland; Laboratoire de Chrono-Environnement, UMR CNRS 6249, UFR des Sciences et Techniques, 16 route de Gray, Université de Franche-Comté, 25030 Besançon, France
| | - Gerd Gleixner
- Max Planck Institute for Biogeochemistry, P.O. Box 100164, 07701 Jena, Germany
| | - Jukka Pumpanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland
| | - Michael Bahn
- Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, 6020 Innsbruck, Austria
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Desalme D, Priault P, Gérant D, Dannoura M, Maillard P, Plain C, Epron D. Seasonal variations drive short-term dynamics and partitioning of recently assimilated carbon in the foliage of adult beech and pine. THE NEW PHYTOLOGIST 2017; 213:140-153. [PMID: 27513732 DOI: 10.1111/nph.14124] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 06/28/2016] [Indexed: 06/06/2023]
Abstract
13 CO2 pulse-labelling experiments were performed in situ on adult beeches (Fagus sylvatica) and pines (Pinus pinaster) at different phenological stages to study seasonal and interspecific short-term dynamics and partitioning of recently assimilated carbon (C) in leaves. Polar fraction (PF, including soluble sugars, amino acids and organic acids) and starch were purified from foliage sampled during a 10-d chase period. C contents, isotopic compositions and 13 C dynamics parameters were determined in bulk foliage, PF and starch. Decrease in 13 C amount in bulk foliage followed a two-pool exponential model highlighting 13 C partitioning between 'mobile' and 'stable' pools, the relative proportion of the latter being maximal in beech leaves in May. Early in the growing season, new foliage acted as a strong C sink in both species, but although young leaves and needles were already photosynthesizing, the latter were still supplied with previous-year needle photosynthates 2 months after budburst. Mean 13 C residence times (MRT) were minimal in summer, indicating fast photosynthate export to supply perennial organ growth in both species. In late summer, MRT differed between senescing beech leaves and overwintering pine needles. Seasonal variations of 13 C partitioning and dynamics in field-grown tree foliage are closely linked to phenological differences between deciduous and evergreen trees.
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Affiliation(s)
- Dorine Desalme
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Pierrick Priault
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Dominique Gérant
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Masako Dannoura
- INRA, UMR 1263, F-33883 Villenave d'Ornon, France
- Laboratory of Forest Utilization, Kyoto University, Kyoto 606-8502, Japan
| | - Pascale Maillard
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Caroline Plain
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
| | - Daniel Epron
- Ecologie et Ecophysiologie Forestières, Université de Lorraine, INRA, UMR 1137, Vandoeuvre-lès-Nancy F-54500, France
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22
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Ait Lahmidi N, Courty PE, Brulé D, Chatagnier O, Arnould C, Doidy J, Berta G, Lingua G, Wipf D, Bonneau L. Sugar exchanges in arbuscular mycorrhiza: RiMST5 and RiMST6, two novel Rhizophagus irregularis monosaccharide transporters, are involved in both sugar uptake from the soil and from the plant partner. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 107:354-363. [PMID: 27362299 DOI: 10.1016/j.plaphy.2016.06.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 06/16/2016] [Accepted: 06/16/2016] [Indexed: 05/27/2023]
Abstract
Arbuscular mycorrhizal (AM) fungi are associated with about 80% of land plants. AM fungi provide inorganic nutrients to plants and in return up to 20% of the plant-fixed CO2 is transferred to the fungal symbionts. Since AM fungi are obligate biotrophs, unraveling how sugars are provided to the fungus partner is a key for understanding the functioning of the symbiosis. In this study, we identified two new monosaccharide transporters from Rhizophagus irregularis (RiMST5 and RiMST6) that we characterized as functional high affinity monosaccharide transporters. RiMST6 was characterized as a glucose specific, high affinity H(+) co-transporter. We provide experimental support for a primary role of both RiMST5 and RiMST6 in sugar uptake directly from the soil. The expression patterns of RiMSTs in response to partial light deprivation and to interaction with different host plants were investigated. Expression of genes coding for RiMSTs was transiently enhanced after 48 h of shading and was unambiguously dependent on the host plant species. These results cast doubt on the 'fair trade' principle under carbon-limiting conditions. Therefore, in light of these findings, the possible mechanisms involved in the modulation between mutualism and parasitism in plant-AM fungus interactions are discussed.
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Affiliation(s)
- Nassima Ait Lahmidi
- INRA, UMR 1347 Agroécologie Pôle Interactions Plantes Microorganismes -ERL6300 CNRS, 17 rue Sully, 21065, Dijon, France.
| | - Pierre-Emmanuel Courty
- Zurich-Basel Plant Science Center, Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, 4056, Basel, Switzerland
| | - Daphnée Brulé
- Zurich-Basel Plant Science Center, Department of Environmental Sciences, Botany, University of Basel, Hebelstrasse 1, 4056, Basel, Switzerland
| | - Odile Chatagnier
- INRA, UMR 1347 Agroécologie Pôle Interactions Plantes Microorganismes -ERL6300 CNRS, 17 rue Sully, 21065, Dijon, France
| | - Christine Arnould
- INRA, UMR 1347 Agroécologie Pôle Interactions Plantes Microorganismes -ERL6300 CNRS, 17 rue Sully, 21065, Dijon, France
| | - Joan Doidy
- INRA, UMR 1347 Agroécologie Pôle Interactions Plantes Microorganismes -ERL6300 CNRS, 17 rue Sully, 21065, Dijon, France
| | - Graziella Berta
- Università degli Studi del Piemonte Orientale Amedeo Avogadro, Dipartimento di Scienze e Innovazione Tecnologica, viale T. Michel, 11, 15121, Alessandria, Italy
| | - Guido Lingua
- Università degli Studi del Piemonte Orientale Amedeo Avogadro, Dipartimento di Scienze e Innovazione Tecnologica, viale T. Michel, 11, 15121, Alessandria, Italy
| | - Daniel Wipf
- Université de Bourgogne-Franche-Comté, UMR 1347 Agroécologie Pôle Interactions Plantes Microorganismes -ERL 6300 CNRS, 17 rue Sully, 21065, Dijon, France
| | - Laurent Bonneau
- Université de Bourgogne-Franche-Comté, UMR 1347 Agroécologie Pôle Interactions Plantes Microorganismes -ERL 6300 CNRS, 17 rue Sully, 21065, Dijon, France
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Hommel R, Siegwolf R, Zavadlav S, Arend M, Schaub M, Galiano L, Haeni M, Kayler ZE, Gessler A. Impact of interspecific competition and drought on the allocation of new assimilates in trees. PLANT BIOLOGY (STUTTGART, GERMANY) 2016; 18:785-96. [PMID: 27061772 DOI: 10.1111/plb.12461] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/07/2016] [Indexed: 05/21/2023]
Abstract
In trees, the interplay between reduced carbon assimilation and the inability to transport carbohydrates to the sites of demand under drought might be one of the mechanisms leading to carbon starvation. However, we largely lack knowledge on how drought effects on new assimilate allocation differ between species with different drought sensitivities and how these effects are modified by interspecific competition. We assessed the fate of (13) C labelled assimilates in above- and belowground plant organs and in root/rhizosphere respired CO2 in saplings of drought-tolerant Norway maple (Acer platanoides) and drought-sensitive European beech (Fagus sylvatica) exposed to moderate drought, either in mono- or mixed culture. While drought reduced stomatal conductance and photosynthesis rates in both species, both maintained assimilate transport belowground. Beech even allocated more new assimilate to the roots under moderate drought compared to non-limited water supply conditions, and this pattern was even more pronounced under interspecific competition. Even though maple was a superior competitor compared to beech under non-limited soil water conditions, as indicated by the changes in above- and belowground biomass of both species in the interspecific competition treatments, we can state that beech was still able to efficiently allocate new assimilate belowground under combined drought and interspecific competition. This might be seen as a strategy to maintain root osmotic potential and to prioritise root functioning. Our results thus show that beech tolerates moderate drought stress plus competition without losing its ability to supply belowground tissues. It remains to be explored in future work if this strategy is also valid during long-term drought exposure.
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Affiliation(s)
- R Hommel
- Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Müncheberg, Germany
| | - R Siegwolf
- Laboratory of Atmospheric Chemistry, Stable Isotopes and Ecosystem Fluxes, Paul Scherrer Institute (PSI), Villigen, Switzerland
| | - S Zavadlav
- Department of Forest Physiology and Genetics, Ljubljana, Slovenia
| | - M Arend
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
| | - M Schaub
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
| | - L Galiano
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
- Institute of Hydrology, University of Freiburg, Freiburg, Germany
| | - M Haeni
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
| | - Z E Kayler
- Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Müncheberg, Germany
| | - A Gessler
- Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Müncheberg, Germany
- Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
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Fuchslueger L, Bahn M, Hasibeder R, Kienzl S, Fritz K, Schmitt M, Watzka M, Richter A. Drought history affects grassland plant and microbial carbon turnover during and after a subsequent drought event. THE JOURNAL OF ECOLOGY 2016. [PMID: 27609992 DOI: 10.5061/dryad.2t3sn] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Drought periods are projected to become more severe and more frequent in many European regions. While effects of single strong droughts on plant and microbial carbon (C) dynamics have been studied in some detail, impacts of recurrent drought events are still little understood.We tested whether the legacy of extreme experimental drought affects responses of plant and microbial C and nitrogen (N) turnover to further drought and rewetting. In a mountain grassland, we conducted a 13C pulse-chase experiment during a naturally occurring drought and rewetting event in plots previously exposed to experimental droughts and in ambient controls (AC). After labelling, we traced 13C below-ground allocation and incorporation into soil microbes using phospholipid fatty acid biomarkers.Drought history (DH) had no effects on the standing shoot and fine root plant biomass. However, plants with experimental DH displayed decreased shoot N concentrations and increased fine root N concentrations relative to those in AC. During the natural drought, plants with DH assimilated and allocated less 13C below-ground; moreover, fine root respiration was reduced and not fuelled by fresh C compared to plants in AC.Regardless of DH, microbial biomass remained stable during natural drought and rewetting. Although microbial communities initially differed in their composition between soils with and without DH, they responded to the natural drought and rewetting in a similar way: gram-positive bacteria increased, while fungal and gram-negative bacteria remained stable. In soils with DH, a strongly reduced uptake of recent plant-derived 13C in microbial biomarkers was observed during the natural drought, pointing to a smaller fraction of active microbes or to a microbial community that is less dependent on plant C. Synthesis. Drought history can induce changes in above- vs. below-ground plant N concentrations and affect the response of plant C turnover to further droughts and rewetting by decreasing plant C uptake and below-ground allocation. DH does not affect the responses of the microbial community to further droughts and rewetting, but alters microbial functioning, particularly the turnover of recent plant-derived carbon, during and after further drought periods.
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Affiliation(s)
- Lucia Fuchslueger
- Department of Microbiology and Ecosystem Science University of Vienna Althanstrasse 14A-1090 Vienna Austria; Present address: National Institute for Amazonian Research (INPA) Av. André Araujo 2936 Aleixo Manaus Amazonas CEP: 69067-375 Brazil
| | - Michael Bahn
- Institute of Ecology University of Innsbruck Sternwartestrasse 15 A-6020 Innsbruck Austria
| | - Roland Hasibeder
- Institute of Ecology University of Innsbruck Sternwartestrasse 15 A-6020 Innsbruck Austria
| | - Sandra Kienzl
- Department of Microbiology and Ecosystem Science University of Vienna Althanstrasse 14 A-1090 Vienna Austria
| | - Karina Fritz
- Institute of Ecology University of Innsbruck Sternwartestrasse 15 A-6020 Innsbruck Austria
| | - Michael Schmitt
- Institute of Ecology University of Innsbruck Sternwartestrasse 15 A-6020 Innsbruck Austria
| | - Margarete Watzka
- Department of Microbiology and Ecosystem Science University of Vienna Althanstrasse 14 A-1090 Vienna Austria
| | - Andreas Richter
- Department of Microbiology and Ecosystem Science University of Vienna Althanstrasse 14 A-1090 Vienna Austria
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25
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Fuchslueger L, Bahn M, Hasibeder R, Kienzl S, Fritz K, Schmitt M, Watzka M, Richter A. Drought history affects grassland plant and microbial carbon turnover during and after a subsequent drought event. THE JOURNAL OF ECOLOGY 2016; 104:1453-1465. [PMID: 27609992 PMCID: PMC4996329 DOI: 10.1111/1365-2745.12593] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 04/18/2016] [Indexed: 05/07/2023]
Abstract
Drought periods are projected to become more severe and more frequent in many European regions. While effects of single strong droughts on plant and microbial carbon (C) dynamics have been studied in some detail, impacts of recurrent drought events are still little understood.We tested whether the legacy of extreme experimental drought affects responses of plant and microbial C and nitrogen (N) turnover to further drought and rewetting. In a mountain grassland, we conducted a 13C pulse-chase experiment during a naturally occurring drought and rewetting event in plots previously exposed to experimental droughts and in ambient controls (AC). After labelling, we traced 13C below-ground allocation and incorporation into soil microbes using phospholipid fatty acid biomarkers.Drought history (DH) had no effects on the standing shoot and fine root plant biomass. However, plants with experimental DH displayed decreased shoot N concentrations and increased fine root N concentrations relative to those in AC. During the natural drought, plants with DH assimilated and allocated less 13C below-ground; moreover, fine root respiration was reduced and not fuelled by fresh C compared to plants in AC.Regardless of DH, microbial biomass remained stable during natural drought and rewetting. Although microbial communities initially differed in their composition between soils with and without DH, they responded to the natural drought and rewetting in a similar way: gram-positive bacteria increased, while fungal and gram-negative bacteria remained stable. In soils with DH, a strongly reduced uptake of recent plant-derived 13C in microbial biomarkers was observed during the natural drought, pointing to a smaller fraction of active microbes or to a microbial community that is less dependent on plant C. Synthesis. Drought history can induce changes in above- vs. below-ground plant N concentrations and affect the response of plant C turnover to further droughts and rewetting by decreasing plant C uptake and below-ground allocation. DH does not affect the responses of the microbial community to further droughts and rewetting, but alters microbial functioning, particularly the turnover of recent plant-derived carbon, during and after further drought periods.
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Affiliation(s)
- Lucia Fuchslueger
- Department of Microbiology and Ecosystem Science University of Vienna Althanstrasse 14A-1090 Vienna Austria; Present address: National Institute for Amazonian Research (INPA) Av. André Araujo 2936 Aleixo Manaus Amazonas CEP: 69067-375 Brazil
| | - Michael Bahn
- Institute of Ecology University of Innsbruck Sternwartestrasse 15 A-6020 Innsbruck Austria
| | - Roland Hasibeder
- Institute of Ecology University of Innsbruck Sternwartestrasse 15 A-6020 Innsbruck Austria
| | - Sandra Kienzl
- Department of Microbiology and Ecosystem Science University of Vienna Althanstrasse 14 A-1090 Vienna Austria
| | - Karina Fritz
- Institute of Ecology University of Innsbruck Sternwartestrasse 15 A-6020 Innsbruck Austria
| | - Michael Schmitt
- Institute of Ecology University of Innsbruck Sternwartestrasse 15 A-6020 Innsbruck Austria
| | - Margarete Watzka
- Department of Microbiology and Ecosystem Science University of Vienna Althanstrasse 14 A-1090 Vienna Austria
| | - Andreas Richter
- Department of Microbiology and Ecosystem Science University of Vienna Althanstrasse 14 A-1090 Vienna Austria
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Hartmann H, Trumbore S. Understanding the roles of nonstructural carbohydrates in forest trees - from what we can measure to what we want to know. THE NEW PHYTOLOGIST 2016; 211:386-403. [PMID: 27061438 DOI: 10.1111/nph.13955] [Citation(s) in RCA: 289] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/01/2016] [Indexed: 05/17/2023]
Abstract
Contents 386 I. 386 II. 388 III. 392 IV. 392 V. 396 VI. 399 399 References 399 SUMMARY: Carbohydrates provide the building blocks for plant structures as well as versatile resources for metabolic processes. The nonstructural carbohydrates (NSC), mainly sugars and starch, fulfil distinct functional roles, including transport, energy metabolism and osmoregulation, and provide substrates for the synthesis of defence compounds or exchange with symbionts involved in nutrient acquisition or defence. At the whole-plant level, NSC storage buffers the asynchrony of supply and demand on diel, seasonal or decadal temporal scales and across plant organs. Despite its central role in plant function and in stand-level carbon cycling, our understanding of storage dynamics, its controls and response to environmental stresses is very limited, even after a century of research. This reflects the fact that often storage is defined by what we can measure, that is, NSC concentrations, and the interpretation of these as a proxy for a single function, storage, rather than the outcome of a range of NSC source and sink functions. New isotopic tools allow direct quantification of timescales involved in NSC dynamics, and show that NSC-C fixed years to decades previously is used to support tree functions. Here we review recent advances, with emphasis on the context of the interactions between NSC, drought and tree mortality.
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Affiliation(s)
- Henrik Hartmann
- Max-Planck Institute for Biogeochemistry, Hans Knöll Str. 10, 07745, Jena, Germany
| | - Susan Trumbore
- Max-Planck Institute for Biogeochemistry, Hans Knöll Str. 10, 07745, Jena, Germany
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27
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Fischer S, Hanf S, Frosch T, Gleixner G, Popp J, Trumbore S, Hartmann H. Pinus sylvestris switches respiration substrates under shading but not during drought. THE NEW PHYTOLOGIST 2015; 207:542-550. [PMID: 25944481 DOI: 10.1111/nph.13452] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 04/13/2015] [Indexed: 06/04/2023]
Abstract
Reduced carbon (C) assimilation during prolonged drought forces trees to rely on stored C to maintain vital processes like respiration. It has been shown, however, that the use of carbohydrates, a major C storage pool and apparently the main respiratory substrate in plants, strongly declines with decreasing plant hydration. Yet no empirical evidence has been produced to what degree other C storage compounds like lipids and proteins may fuel respiration during drought. We exposed young scots pine trees to C limitation using either drought or shading and assessed respiratory substrate use by monitoring the respiratory quotient, δ(13) C of respired CO2 and concentrations of the major storage compounds, that is, carbohydrates, lipids and amino acids. Only shaded trees shifted from carbohydrate-dominated to lipid-dominated respiration and showed progressive carbohydrate depletion. In drought trees, the fraction of carbohydrates used in respiration did not decline but respiration rates were strongly reduced. The lower consumption and potentially allocation from other organs may have caused initial carbohydrate content to remain constant during the experiment. Our results suggest that respiratory substrates other than carbohydrates are used under carbohydrate limitation but not during drought. Thus, respiratory substrate shift cannot provide an efficient means to counterbalance C limitation under natural drought.
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Affiliation(s)
- Sarah Fischer
- Max-Planck Institute for Biogeochemistry, Hans Knoll Str. 10, 07745, Jena, Germany
| | - Stefan Hanf
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Torsten Frosch
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
- Institute for Physical Chemistry, Friedrich Schiller University, Helmholtzweg 4, 07743, Jena, Germany
| | - Gerd Gleixner
- Max-Planck Institute for Biogeochemistry, Hans Knoll Str. 10, 07745, Jena, Germany
| | - Jürgen Popp
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
- Institute for Physical Chemistry, Friedrich Schiller University, Helmholtzweg 4, 07743, Jena, Germany
- Abbe Center of Photonics, Friedrich Schiller University, Helmholtzweg 4, 07743, Jena, Germany
| | - Susan Trumbore
- Max-Planck Institute for Biogeochemistry, Hans Knoll Str. 10, 07745, Jena, Germany
| | - Henrik Hartmann
- Max-Planck Institute for Biogeochemistry, Hans Knoll Str. 10, 07745, Jena, Germany
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28
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Blessing CH, Werner RA, Siegwolf R, Buchmann N. Allocation dynamics of recently fixed carbon in beech saplings in response to increased temperatures and drought. TREE PHYSIOLOGY 2015; 35:585-98. [PMID: 25877767 DOI: 10.1093/treephys/tpv024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 03/08/2015] [Indexed: 05/05/2023]
Abstract
The response of carbon allocation to drought has often been studied in terms of short-term transport velocity of recently fixed carbon from leaves to roots and root respiration. However, its dynamic response to other environmental conditions, e.g., to changes in temperature, is less clear. Here, we investigated the effects of drought, increased temperatures and their combination on transport velocity as well as on distribution of recent photoassimilates for different compounds, such as sugars, starch, organic acids and amino acids. We used a (13)CO(2) pulse-labelling approach and studied the recovery of (13)C in different plant tissues and compounds of beech saplings (Fagus sylvatica L.) during a 9-day chase period. Neither total dry biomass nor dry weights of leaves or roots were affected by drought or increased temperatures. Generally, the fast transfer of recently fixed assimilates from leaves to roots took about 1 day, while (13)C enrichment in soil CO(2) efflux peaked only 2 days after labelling. Increased temperatures prolonged mean transfer times of recent photoassimilates from the leaves to the roots, probably caused by enhanced intermediate storage alongside basipetal transfer, clearly impacting short-term carbon allocation. This temperature effect was seen in the delayed peak in (13)C excess of root sugars, decoupling the roots from the leaves in the short term. On average, ∼40% of the (13)C label initially present in the plant was recovered in the roots (over all treatment combinations), providing strong evidence for preferred carbon allocation into the roots at the end of the growing season. Root starch was the principal compound for long-term storage of carbon, whereas leaf (transitory) starch was remobilized again after some days, exhibiting the longest mean residence times under dry and warm conditions. These observation clearly point to different functionalities of the same compound (i.e., starch) in different plant tissues and the crucial role of roots for long-term carbon storage.
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Affiliation(s)
- Carola H Blessing
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8048 Zurich, Switzerland
| | - Roland A Werner
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8048 Zurich, Switzerland
| | - Rolf Siegwolf
- Paul Scherrer Institute (PSI), Laboratory of Atmospheric Chemistry, CH-5232 Villigen PSI, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8048 Zurich, Switzerland
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29
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Flores-Rentería D, Curiel Yuste J, Rincón A, Brearley FQ, García-Gil JC, Valladares F. Habitat Fragmentation can Modulate Drought Effects on the Plant-soil-microbial System in Mediterranean Holm Oak (Quercus ilex) Forests. MICROBIAL ECOLOGY 2015; 69:798-812. [PMID: 25724140 DOI: 10.1007/s00248-015-0584-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 02/13/2015] [Indexed: 06/04/2023]
Abstract
Ecological transformations derived from habitat fragmentation have led to increased threats to above-ground biodiversity. However, the impacts of forest fragmentation on soils and their microbial communities are not well understood. We examined the effects of contrasting fragment sizes on the structure and functioning of soil microbial communities from holm oak forest patches in two bioclimatically different regions of Spain. We used a microcosm approach to simulate the annual summer drought cycle and first autumn rainfall (rewetting), evaluating the functional response of a plant-soil-microbial system. Forest fragment size had a significant effect on physicochemical characteristics and microbial functioning of soils, although the diversity and structure of microbial communities were not affected. The response of our plant-soil-microbial systems to drought was strongly modulated by the bioclimatic conditions and the fragment size from where the soils were obtained. Decreasing fragment size modulated the effects of drought by improving local environmental conditions with higher water and nutrient availability. However, this modulation was stronger for plant-soil-microbial systems built with soils from the northern region (colder and wetter) than for those built with soils from the southern region (warmer and drier) suggesting that the responsiveness of the soil-plant-microbial system to habitat fragmentation was strongly dependent on both the physicochemical characteristics of soils and the historical adaptation of soil microbial communities to specific bioclimatic conditions. This interaction challenges our understanding of future global change scenarios in Mediterranean ecosystems involving drier conditions and increased frequency of forest fragmentation.
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Affiliation(s)
- Dulce Flores-Rentería
- Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales (MNCN), Spanish Scientific Council (CSIC), Serrano 115bis, 28006, Madrid, Spain,
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30
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Malik AA, Dannert H, Griffiths RI, Thomson BC, Gleixner G. Rhizosphere bacterial carbon turnover is higher in nucleic acids than membrane lipids: implications for understanding soil carbon cycling. Front Microbiol 2015; 6:268. [PMID: 25914679 PMCID: PMC4391234 DOI: 10.3389/fmicb.2015.00268] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/18/2015] [Indexed: 11/13/2022] Open
Abstract
Using a pulse chase (13)CO2 plant labeling experiment we compared the flow of plant carbon into macromolecular fractions of rhizosphere soil microorganisms. Time dependent (13)C dilution patterns in microbial cellular fractions were used to calculate their turnover time. The turnover times of microbial biomolecules were found to vary: microbial RNA (19 h) and DNA (30 h) turned over fastest followed by chloroform fumigation extraction-derived soluble cell lysis products (14 days), while phospholipid fatty acids (PLFAs) had the slowest turnover (42 days). PLFA/NLFA (13)C analyses suggest that both mutualistic arbuscular mycorrhizal and saprophytic fungi are dominant in initial plant carbon uptake. In contrast, high initial (13)C enrichment in RNA hints at bacterial importance in initial C uptake due to the dominance of bacterial derived RNA in total extracts of soil RNA. To explain this discrepancy, we observed low renewal rate of bacterial lipids, which may therefore bias lipid fatty acid based interpretations of the role of bacteria in soil microbial food webs. Based on our findings, we question current assumptions regarding plant-microbe carbon flux and suggest that the rhizosphere bacterial contribution to plant assimilate uptake could be higher. This highlights the need for more detailed quantitative investigations with nucleic acid biomarkers to further validate these findings.
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Affiliation(s)
- Ashish A Malik
- Department of Biogeochemical Processes, Max Planck Institute for Biogeochemistry Jena, Germany
| | - Helena Dannert
- Department of Biogeochemical Processes, Max Planck Institute for Biogeochemistry Jena, Germany
| | | | | | - Gerd Gleixner
- Department of Biogeochemical Processes, Max Planck Institute for Biogeochemistry Jena, Germany
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31
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Kaiser C, Kilburn MR, Clode PL, Fuchslueger L, Koranda M, Cliff JB, Solaiman ZM, Murphy DV. Exploring the transfer of recent plant photosynthates to soil microbes: mycorrhizal pathway vs direct root exudation. THE NEW PHYTOLOGIST 2015; 205:1537-1551. [PMID: 25382456 PMCID: PMC4357392 DOI: 10.1111/nph.13138] [Citation(s) in RCA: 170] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/23/2014] [Indexed: 05/19/2023]
Abstract
Plants rapidly release photoassimilated carbon (C) to the soil via direct root exudation and associated mycorrhizal fungi, with both pathways promoting plant nutrient availability. This study aimed to explore these pathways from the root's vascular bundle to soil microbial communities. Using nanoscale secondary ion mass spectrometry (NanoSIMS) imaging and (13) C-phospho- and neutral lipid fatty acids, we traced in-situ flows of recently photoassimilated C of (13) CO2 -exposed wheat (Triticum aestivum) through arbuscular mycorrhiza (AM) into root- and hyphae-associated soil microbial communities. Intraradical hyphae of AM fungi were significantly (13) C-enriched compared to other root-cortex areas after 8 h of labelling. Immature fine root areas close to the root tip, where AM features were absent, showed signs of passive C loss and co-location of photoassimilates with nitrogen taken up from the soil solution. A significant and exclusively fresh proportion of (13) C-photosynthates was delivered through the AM pathway and was utilised by different microbial groups compared to C directly released by roots. Our results indicate that a major release of recent photosynthates into soil leave plant roots via AM intraradical hyphae already upstream of passive root exudations. AM fungi may act as a rapid hub for translocating fresh plant C to soil microbes.
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Affiliation(s)
- Christina Kaiser
- Soil Biology and Molecular Ecology Group, School of Earth and Environment, Institute of Agriculture, The University of Western AustraliaCrawley, WA, 6009, Australia
- Department of Microbiology and Ecosystem Science, Division of Terrestrial Ecosystem Research, Faculty of Life Sciences, University of ViennaAlthanstrasse 14, Vienna, A-1090, Austria
| | - Matt R Kilburn
- Centre for Microscopy, Characterisation and Analysis, The University of Western AustraliaCrawley, WA, 6009, Australia
| | - Peta L Clode
- Centre for Microscopy, Characterisation and Analysis, The University of Western AustraliaCrawley, WA, 6009, Australia
| | - Lucia Fuchslueger
- Department of Microbiology and Ecosystem Science, Division of Terrestrial Ecosystem Research, Faculty of Life Sciences, University of ViennaAlthanstrasse 14, Vienna, A-1090, Austria
| | - Marianne Koranda
- Department of Microbiology and Ecosystem Science, Division of Terrestrial Ecosystem Research, Faculty of Life Sciences, University of ViennaAlthanstrasse 14, Vienna, A-1090, Austria
| | - John B Cliff
- Centre for Microscopy, Characterisation and Analysis, The University of Western AustraliaCrawley, WA, 6009, Australia
| | - Zakaria M Solaiman
- Soil Biology and Molecular Ecology Group, School of Earth and Environment, Institute of Agriculture, The University of Western AustraliaCrawley, WA, 6009, Australia
| | - Daniel V Murphy
- Soil Biology and Molecular Ecology Group, School of Earth and Environment, Institute of Agriculture, The University of Western AustraliaCrawley, WA, 6009, Australia
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32
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Hasibeder R, Fuchslueger L, Richter A, Bahn M. Summer drought alters carbon allocation to roots and root respiration in mountain grassland. THE NEW PHYTOLOGIST 2015; 205:1117-1127. [PMID: 25385284 PMCID: PMC4303983 DOI: 10.1111/nph.13146] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Accepted: 09/21/2014] [Indexed: 05/04/2023]
Abstract
Drought affects the carbon (C) source and sink activities of plant organs, with potential consequences for belowground C allocation, a key process of the terrestrial C cycle. The responses of belowground C allocation dynamics to drought are so far poorly understood. We combined experimental rain exclusion with (13)C pulse labelling in a mountain meadow to analyse the effects of summer drought on the dynamics of belowground allocation of recently assimilated C and how it is partitioned among different carbohydrate pools and root respiration. Severe soil moisture deficit decreased the ecosystem C uptake and the amounts and velocity of C allocated from shoots to roots. However, the proportion of recently assimilated C translocated belowground remained unaffected by drought. Reduced root respiration, reflecting reduced C demand under drought, was increasingly sustained by C reserves, whilst recent assimilates were preferentially allocated to root storage and an enlarged pool of osmotically active compounds. Our results indicate that under drought conditions the usage of recent photosynthates is shifted from metabolic activity to osmotic adjustment and storage compounds.
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Affiliation(s)
- Roland Hasibeder
- Institute of Ecology, University of InnsbruckSternwartestraße 15, 6020, Innsbruck, Austria
| | - Lucia Fuchslueger
- Division of Terrestrial Ecosystem Research, Department of Chemical Ecology and Ecosystem Research, University of ViennaAlthanstraße 14, 1090, Vienna, Austria
| | - Andreas Richter
- Division of Terrestrial Ecosystem Research, Department of Chemical Ecology and Ecosystem Research, University of ViennaAlthanstraße 14, 1090, Vienna, Austria
| | - Michael Bahn
- Institute of Ecology, University of InnsbruckSternwartestraße 15, 6020, Innsbruck, Austria
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33
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Legay N, Baxendale C, Grigulis K, Krainer U, Kastl E, Schloter M, Bardgett RD, Arnoldi C, Bahn M, Dumont M, Poly F, Pommier T, Clément JC, Lavorel S. Contribution of above- and below-ground plant traits to the structure and function of grassland soil microbial communities. ANNALS OF BOTANY 2014; 114:1011-21. [PMID: 25122656 PMCID: PMC4171078 DOI: 10.1093/aob/mcu169] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 07/03/2014] [Indexed: 05/04/2023]
Abstract
BACKGROUND AND AIMS Abiotic properties of soil are known to be major drivers of the microbial community within it. Our understanding of how soil microbial properties are related to the functional structure and diversity of plant communities, however, is limited and largely restricted to above-ground plant traits, with the role of below-ground traits being poorly understood. This study investigated the relative contributions of soil abiotic properties and plant traits, both above-ground and below-ground, to variations in microbial processes involved in grassland nitrogen turnover. METHODS In mountain grasslands distributed across three European sites, a correlative approach was used to examine the role of a large range of plant functional traits and soil abiotic factors on microbial variables, including gene abundance of nitrifiers and denitrifiers and their potential activities. KEY RESULTS Direct effects of soil abiotic parameters were found to have the most significant influence on the microbial groups investigated. Indirect pathways via plant functional traits contributed substantially to explaining the relative abundance of fungi and bacteria and gene abundances of the investigated microbial communities, while they explained little of the variance in microbial activities. Gene abundances of nitrifiers and denitrifiers were most strongly related to below-ground plant traits, suggesting that they were the most relevant traits for explaining variation in community structure and abundances of soil microbes involved in nitrification and denitrification. CONCLUSIONS The results suggest that consideration of plant traits, and especially below-ground traits, increases our ability to describe variation in the abundances and the functional characteristics of microbial communities in grassland soils.
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Affiliation(s)
- N Legay
- Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, Grenoble, France
| | - C Baxendale
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - K Grigulis
- Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, Grenoble, France Station Alpine Joseph Fourier, UMS 3370 CNRS - Université Joseph Fourier, BP 53, 2233 Rue de la Piscine, 38041 Grenoble Cedex 9, France
| | - U Krainer
- Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, A-6020 Innsbruck, Austria
| | - E Kastl
- Research Unit for Environmental Genomics, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - M Schloter
- Research Unit for Environmental Genomics, Helmholtz Zentrum München, Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH), Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - R D Bardgett
- Faculty of Life Sciences, Michael Smith Building, The University of Manchester, Oxford Road, Manchester M13 9PT, UK and
| | - C Arnoldi
- Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, Grenoble, France
| | - M Bahn
- Institute of Ecology, University of Innsbruck, Sternwartestrasse 15, A-6020 Innsbruck, Austria
| | - M Dumont
- Laboratoire d'Ecologie Microbienne, Université Lyon1, Université de Lyon, 15 USC INRA 1364, UMR CNRS 5557, Villeurbanne Cedex, France
| | - F Poly
- Laboratoire d'Ecologie Microbienne, Université Lyon1, Université de Lyon, 15 USC INRA 1364, UMR CNRS 5557, Villeurbanne Cedex, France
| | - T Pommier
- Laboratoire d'Ecologie Microbienne, Université Lyon1, Université de Lyon, 15 USC INRA 1364, UMR CNRS 5557, Villeurbanne Cedex, France
| | - J C Clément
- Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, Grenoble, France
| | - S Lavorel
- Laboratoire d'Ecologie Alpine, UMR CNRS 5553, Université Joseph Fourier, Grenoble, France
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Salmon Y, Barnard RL, Buchmann N. Physiological controls of the isotopic time lag between leaf assimilation and soil CO 2 efflux. FUNCTIONAL PLANT BIOLOGY : FPB 2014; 41:850-859. [PMID: 32481039 DOI: 10.1071/fp13212] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2013] [Accepted: 02/25/2014] [Indexed: 06/11/2023]
Abstract
Environmental factors and physiological controls on photosynthesis influence the carbon isotopic signature of ecosystem respiration. Many ecosystem studies have used stable carbon isotopes to investigate environmental controls on plant carbon transfer from above- to belowground. However, a clear understanding of the internal mechanisms underlying time-lagged responses of carbon isotopic signatures in ecosystem respiration to environmental changes is still lacking. This study addressed plant physiological controls on the transfer time of recently assimilated carbon from assimilation to respiration. We produced a set of six wheat plants with varying physiological characteristics, by growing them under a wide range of nitrogen supply and soil water content levels under standardised conditions. The plants were pulse-labelled with 13C-CO2, and the isotopic signature of CO2 respired in the dark by plants and soil was monitored continuously over two days. Stomatal conductance (gs) was strongly related to the rate of transfer of recently assimilated carbon belowground. The higher gs, the faster newly assimilated carbon was allocated belowground and the faster it was respired in the soil. Our results suggest that carbon sink strength of plant tissues may be a major driver of transfer velocity of recently assimilated carbon to plant respiratory tissues and soil respiration.
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Affiliation(s)
- Yann Salmon
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8092 Zurich, Switzerland
| | - Romain L Barnard
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8092 Zurich, Switzerland
| | - Nina Buchmann
- Institute of Agricultural Sciences, ETH Zurich, Universitätstrasse 2, 8092 Zurich, Switzerland
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Curiel Yuste J, Fernandez-Gonzalez AJ, Fernandez-Lopez M, Ogaya R, Penuelas J, Lloret F. Functional diversification within bacterial lineages promotes wide functional overlapping between taxonomic groups in a Mediterranean forest soil. FEMS Microbiol Ecol 2014; 90:54-67. [DOI: 10.1111/1574-6941.12373] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 06/10/2014] [Accepted: 06/11/2014] [Indexed: 11/28/2022] Open
Affiliation(s)
| | | | | | - Romá Ogaya
- CREAF; Cerdanyola del Vallès (Barcelona) Spain
- Global Ecology Unit CREAF-CEAB-CSIC-UAB; CSIC; Cerdanyola del Vallès (Barcelona) Spain
| | - Josep Penuelas
- CREAF; Cerdanyola del Vallès (Barcelona) Spain
- Global Ecology Unit CREAF-CEAB-CSIC-UAB; CSIC; Cerdanyola del Vallès (Barcelona) Spain
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36
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Burri S, Sturm P, Baur T, Barthel M, Knohl A, Buchmann N. The effect of physical back-diffusion of 13CO2 tracer on the coupling between photosynthesis and soil CO2 efflux in grassland. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2014; 50:497-513. [PMID: 24617651 DOI: 10.1080/10256016.2014.893237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Pulse labelling experiments provide a common tool to study short-term processes in the plant-soil system and investigate below-ground carbon allocation as well as the coupling of soil CO(2) efflux to photosynthesis. During the first hours after pulse labelling, the measured isotopic signal of soil CO(2) efflux is a combination of both physical tracer diffusion into and out of the soil as well as biological tracer release via root and microbial respiration. Neglecting physical back-diffusion can lead to misinterpretation regarding time lags between photosynthesis and soil CO(2) efflux in grassland or any ecosystem type where the above-ground plant parts cannot be labelled in gas-tight chambers separated from the soil. We studied the effects of physical (13)CO(2) tracer back-diffusion in pulse labelling experiments in grassland, focusing on the isotopic signature of soil CO(2) efflux. Having accounted for back-diffusion, the estimated time lag for first tracer appearance in soil CO(2) efflux changed from 0 to 1.81±0.56 h (mean±SD) and the time lag for maximum tracer appearance from 2.67±0.39 to 9.63±3.32 h (mean±SD). Thus, time lags were considerably longer when physical tracer diffusion was considered. Using these time lags after accounting for physical back-diffusion, high nocturnal soil CO(2) efflux rates could be related to daytime rates of gross primary productivity (R(2)=0.84). Moreover, pronounced diurnal patterns in the δ(13)C of soil CO(2) efflux were found during the decline of the tracer over 3 weeks. Possible mechanisms include diurnal changes in the relative contributions of autotrophic and heterotrophic soil respiration as well as their respective δ(13)C values. Thus, after accounting for physical back-diffusion, we were able to quantify biological time lags in the coupling of photosynthesis and soil CO(2) efflux in grassland at the diurnal time scale.
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Affiliation(s)
- Susanne Burri
- a Institute of Agricultural Sciences, ETH Zurich , Zurich , Switzerland
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Fuchslueger L, Bahn M, Fritz K, Hasibeder R, Richter A. Experimental drought reduces the transfer of recently fixed plant carbon to soil microbes and alters the bacterial community composition in a mountain meadow. THE NEW PHYTOLOGIST 2014; 201:916-927. [PMID: 24171922 PMCID: PMC3908363 DOI: 10.1111/nph.12569] [Citation(s) in RCA: 122] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/24/2013] [Indexed: 05/19/2023]
Abstract
Drought affects plants and soil microorganisms, but it is still not clear how it alters the carbon (C) transfer at the plant-microbial interface. Here, we tested direct and indirect effects of drought on soil microbes and microbial turnover of recent plant-derived C in a mountain meadow. Microbial community composition was assessed using phospholipid fatty acids (PLFAs); the allocation of recent plant-derived C to microbial groups was analysed by pulse-labelling of canopy sections with (13) CO2 and the subsequent tracing of the label into microbial PLFAs. Microbial biomass was significantly higher in plots exposed to a severe experimental drought. In addition, drought induced a shift of the microbial community composition, mainly driven by an increase of Gram-positive bacteria. Drought reduced belowground C allocation, but not the transfer of recently plant-assimilated C to fungi, and in particular reduced tracer uptake by bacteria. This was accompanied by an increase of (13) C in the extractable organic C pool during drought, which was even more pronounced after plots were mown. We conclude that drought weakened the link between plant and bacterial, but not fungal, C turnover, and facilitated the growth of potentially slow-growing, drought-adapted soil microbes, such as Gram-positive bacteria.
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Affiliation(s)
- Lucia Fuchslueger
- Department of Microbiology and Ecosystem Science, University of ViennaAlthanstr. 14, A-1090, Vienna, Austria
| | - Michael Bahn
- Institute of Ecology, University of InnsbruckInnsbruck, Austria
| | - Karina Fritz
- Institute of Ecology, University of InnsbruckInnsbruck, Austria
| | | | - Andreas Richter
- Department of Microbiology and Ecosystem Science, University of ViennaAlthanstr. 14, A-1090, Vienna, Austria
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Matamala R, Stover DB. Introduction to a Virtual Special Issue: modeling the hidden half - the root of our problem. THE NEW PHYTOLOGIST 2013; 200:939-942. [PMID: 24571663 DOI: 10.1111/nph.12583] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Affiliation(s)
- Roser Matamala
- Argonne National Laboratory, Biosciences Division, Argonne, IL, 60439, USA
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The allocation of assimilated carbon to shoot growth: in situ assessment in natural grasslands reveals nitrogen effects and interspecific differences. Oecologia 2013; 174:1085-95. [PMID: 24276773 DOI: 10.1007/s00442-013-2838-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 11/09/2013] [Indexed: 10/26/2022]
Abstract
In grasslands, sustained nitrogen loading would increase the proportion of assimilated carbon allocated to shoot growth (A shoot), because it would decrease allocation to roots and also encourage the contribution of species with inherently high A shoot. However, in situ measurements of carbon allocation are scarce. Therefore, it is unclear to what extent species that coexist in grasslands actually differ in their allocation strategy or in their response to nitrogen. We used a mobile facility to perform steady-state (13)C-labeling of field stands to quantify, in winter and autumn, the daily relative photosynthesis rate (RPR~tracer assimilated over one light-period) and A shoot (~tracer remaining in shoots after a 100 degree days chase period) in four individual species with contrasting morpho-physiological characteristics coexisting in a temperate grassland of Argentina, either fertilized or not with nitrogen, and either cut intermittently or grazed continuously. Plasticity in response to nitrogen was substantial in most species, as indicated by positive correlations between A shoot and shoot nitrogen concentration. There was a notable interspecific difference: productive species with higher RPR, enhanced by fertilization and characterized by faster leaf turnover rate, allocated ~20% less of the assimilated carbon to shoot growth than species of lower productivity (and quality) characterized by longer leaf life spans and phyllochrons. These results imply that, opposite to the expected response, sustained nitrogen loading would change little the A shoot of grassland communities if increases at the species-level are offset by decreases associated with replacement of 'low RPR-high A shoot' species by 'high RPR-low A shoot' species.
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Mulder C, Ahrestani FS, Bahn M, Bohan DA, Bonkowski M, Griffiths BS, Guicharnaud RA, Kattge J, Krogh PH, Lavorel S, Lewis OT, Mancinelli G, Naeem S, Peñuelas J, Poorter H, Reich PB, Rossi L, Rusch GM, Sardans J, Wright IJ. Connecting the Green and Brown Worlds. ADV ECOL RES 2013. [DOI: 10.1016/b978-0-12-420002-9.00002-0] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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