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Korn R, Berg C, Bersier LF, Gray SM, Thallinger GG. Habitat conditions and not moss composition mediate microbial community structure in Swiss peatlands. Environ Microbiol 2024; 26:e16631. [PMID: 38757479 DOI: 10.1111/1462-2920.16631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 04/05/2024] [Indexed: 05/18/2024]
Abstract
Peatlands, one of the oldest ecosystems, globally store significant amounts of carbon and freshwater. However, they are under severe threat from human activities, leading to changes in water, nutrient and temperature regimes in these delicate systems. Such shifts can trigger a substantial carbon flux into the atmosphere and diminish the water-holding capacity of peatlands. Microbes associated with moss in peatlands play a crucial role in providing these ecosystem services, which are at risk due to global change. Therefore, understanding the factors influencing microbial composition and function is vital. Our study focused on five peatlands along an altitudinal gradient in Switzerland, where we sampled moss on hummocks containing Sarracenia purpurea. Structural equation modelling revealed that habitat condition was the primary predictor of community structure and directly influenced other environmental variables. Interestingly, the microbial composition was not linked to the local moss species identity. Instead, microbial communities varied significantly between sites due to differences in acidity levels and nitrogen availability. This finding was also mirrored in a co-occurrence network analysis, which displayed a distinct distribution of indicator species for acidity and nitrogen availability. Therefore, peatland conservation should take into account the critical habitat characteristics of moss-associated microbial communities.
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Affiliation(s)
- Rachel Korn
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | | | | | - Sarah M Gray
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Gerhard G Thallinger
- Institute of Biomedical Informatics, Graz University of Technology, Graz, Austria
- OMICS Center Graz, BioTechMed, Graz, Austria
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2
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Shao S, Wu J, He H, Moore TR, Bubier J, Larmola T, Juutinen S, Roulet NT. Ericoid mycorrhizal fungi mediate the response of ombrotrophic peatlands to fertilization: a modeling study. THE NEW PHYTOLOGIST 2023; 238:80-95. [PMID: 36300568 DOI: 10.1111/nph.18555] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 10/07/2022] [Indexed: 06/16/2023]
Abstract
Ericaceous shrubs adapt to the nutrient-poor conditions in ombrotrophic peatlands by forming symbiotic associations with ericoid mycorrhizal (ERM) fungi. Increased nutrient availability may diminish the role of ERM pathways in shrub nutrient uptake, consequently altering the biogeochemical cycling within bogs. To explore the significance of ERM fungi in ombrotrophic peatlands, we developed the model MWMmic (a peat cohort-based biogeochemical model) into MWMmic-NP by explicitly incorporating plant-soil nitrogen (N) and phosphorus (P) cycling and ERM fungi processes. The new model was applied to simulate the biogeochemical cycles in the Mer Bleue (MB) bog in Ontario, Canada, and their responses to fertilization. MWMmic_NP reproduced the carbon(C)-N-P cycles and vegetation dynamics observed in the MB bog, and their responses to fertilization. Our simulations showed that fertilization increased shrub biomass by reducing the C allocation to ERM fungi, subsequently suppressing the growth of underlying Sphagnum mosses, and decreasing the peatland C sequestration. Our species removal simulation further demonstrated that ERM fungi were key to maintaining the shrub-moss coexistence and C sink function of bogs. Our results suggest that ERM fungi play a significant role in the biogeochemical cycles in ombrotrophic peatlands and should be considered in future modeling efforts.
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Affiliation(s)
- Siya Shao
- Department of Geography, McGill University, Montreal, QC, H3A 0G4, Canada
- Department of Biological Sciences, Dartmouth College, Hanover, NH, 03755, USA
| | - Jianghua Wu
- Environment and Sustainability, School of Science and the Environment, Memorial University of Newfoundland, St John's, NL, A1C 5S7, Canada
| | - Hongxing He
- Department of Geography, McGill University, Montreal, QC, H3A 0G4, Canada
| | - Tim R Moore
- Department of Geography, McGill University, Montreal, QC, H3A 0G4, Canada
| | - Jill Bubier
- Department of Environmental Studies, Mount Holyoke College, South Hadley, MA, 01075, USA
| | - Tuula Larmola
- Natural Resources Institute Finland (Luke), 00790, Helsinki, Finland
| | - Sari Juutinen
- Finnish Meteorological Institute, 00560, Helsinki, Finland
| | - Nigel T Roulet
- Department of Geography, McGill University, Montreal, QC, H3A 0G4, Canada
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3
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Panis F, Rompel A. The Novel Role of Tyrosinase Enzymes in the Storage of Globally Significant Amounts of Carbon in Wetland Ecosystems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:11952-11968. [PMID: 35944157 PMCID: PMC9454253 DOI: 10.1021/acs.est.2c03770] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/01/2022] [Accepted: 07/05/2022] [Indexed: 05/30/2023]
Abstract
Over the last millennia, wetlands have been sequestering carbon from the atmosphere via photosynthesis at a higher rate than releasing it and, therefore, have globally accumulated 550 × 1015 g of carbon, which is equivalent to 73% of the atmospheric carbon pool. The accumulation of organic carbon in wetlands is effectuated by phenolic compounds, which suppress the degradation of soil organic matter by inhibiting the activity of organic-matter-degrading enzymes. The enzymatic removal of phenolic compounds by bacterial tyrosinases has historically been blocked by anoxic conditions in wetland soils, resulting from waterlogging. Bacterial tyrosinases are a subgroup of oxidoreductases that oxidatively remove phenolic compounds, coupled to the reduction of molecular oxygen to water. The biochemical properties of bacterial tyrosinases have been investigated thoroughly in vitro within recent decades, while investigations focused on carbon fluxes in wetlands on a macroscopic level have remained a thriving yet separated research area so far. In the wake of climate change, however, anoxic conditions in wetland soils are threatened by reduced rainfall and prolonged summer drought. This potentially allows tyrosinase enzymes to reduce the concentration of phenolic compounds, which in turn will increase the release of stored carbon back into the atmosphere. To offer compelling evidence for the novel concept that bacterial tyrosinases are among the key enzymes influencing carbon cycling in wetland ecosystems first, bacterial organisms indigenous to wetland ecosystems that harbor a TYR gene within their respective genome (tyr+) have been identified, which revealed a phylogenetically diverse community of tyr+ bacteria indigenous to wetlands based on genomic sequencing data. Bacterial TYR host organisms covering seven phyla (Acidobacteria, Actinobacteria, Bacteroidetes, Firmicutes, Nitrospirae, Planctomycetes, and Proteobacteria) have been identified within various wetland ecosystems (peatlands, marshes, mangrove forests, bogs, and alkaline soda lakes) which cover a climatic continuum ranging from high arctic to tropic ecosystems. Second, it is demonstrated that (in vitro) bacterial TYR activity is commonly observed at pH values characteristic for wetland ecosystems (ranging from pH 3.5 in peatlands and freshwater swamps to pH 9.0 in soda lakes and freshwater marshes) and toward phenolic compounds naturally present within wetland environments (p-coumaric acid, gallic acid, protocatechuic acid, p-hydroxybenzoic acid, caffeic acid, catechin, and epicatechin). Third, analyzing the available data confirmed that bacterial host organisms tend to exhibit in vitro growth optima at pH values similar to their respective wetland habitats. Based on these findings, it is concluded that, following increased aeration of previously anoxic wetland soils due to climate change, TYRs are among the enzymes capable of reducing the concentration of phenolic compounds present within wetland ecosystems, which will potentially destabilize vast amounts of carbon stored in these ecosystems. Finally, promising approaches to mitigate the detrimental effects of increased TYR activity in wetland ecosystems and the requirement of future investigations of the abundance and activity of TYRs in an environmental setting are presented.
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Kulshrestha S, Jibran R, van Klink JW, Zhou Y, Brummell DA, Albert NW, Schwinn KE, Chagné D, Landi M, Bowman JL, Davies KM. Stress, senescence, and specialized metabolites in bryophytes. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:4396-4411. [PMID: 35259256 PMCID: PMC9291361 DOI: 10.1093/jxb/erac085] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 03/07/2022] [Indexed: 05/04/2023]
Abstract
Life on land exposes plants to varied abiotic and biotic environmental stresses. These environmental drivers contributed to a large expansion of metabolic capabilities during land plant evolution and species diversification. In this review we summarize knowledge on how the specialized metabolite pathways of bryophytes may contribute to stress tolerance capabilities. Bryophytes are the non-tracheophyte land plant group (comprising the hornworts, liverworts, and mosses) and rapidly diversified following the colonization of land. Mosses and liverworts have as wide a distribution as flowering plants with regard to available environments, able to grow in polar regions through to hot desert landscapes. Yet in contrast to flowering plants, for which the biosynthetic pathways, transcriptional regulation, and compound function of stress tolerance-related metabolite pathways have been extensively characterized, it is only recently that similar data have become available for bryophytes. The bryophyte data are compared with those available for angiosperms, including examining how the differing plant forms of bryophytes and angiosperms may influence specialized metabolite diversity and function. The involvement of stress-induced specialized metabolites in senescence and nutrient response pathways is also discussed.
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Affiliation(s)
- Samarth Kulshrestha
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand
| | - Rubina Jibran
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand
| | - John W van Klink
- The New Zealand Institute for Plant and Food Research Limited, Department of Chemistry, Otago University, Dunedin, New Zealand
| | - Yanfei Zhou
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand
| | - David A Brummell
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand
| | - Nick W Albert
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand
| | - Kathy E Schwinn
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand
| | - David Chagné
- The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North 4442, New Zealand
| | - Marco Landi
- Department of Agriculture, Food and Environment, University of Pisa, Italy
| | - John L Bowman
- School of Biological Sciences, Monash University, Melbourne, VIC, Australia
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5
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Wu Y, Xu X, McCarter CPR, Zhang N, Ganzoury MA, Waddington JM, de Lannoy CF. Assessing leached TOC, nutrients and phenols from peatland soils after lab-simulated wildfires: Implications to source water protection. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 822:153579. [PMID: 35114220 DOI: 10.1016/j.scitotenv.2022.153579] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/25/2022] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Pollutant leaching from wildfire-impacted peatland soils (peat) is well-known, but often underestimated when considering boreal ecosystem source water protection and when treating source waters to provide clean drinking water. Burning peat impacts its physical properties and chemical composition, yet the consequences of these transformations to source water quality through pollutant leaching has not been studied in detail. We combusted near-surface boreal peat under simulated peat smoldering conditions at two temperatures (250 °C and 300 °C) and quantified the concentrations of the leached carbon, nutrients and phenols from 5 g peat L-1 reverse osmosis (RO) water suspensions over a 2-day leaching period. For the conditions studied, measured water quality parameters exceeded US surface water guidelines and even exceeded EU and Canadian wastewater/sewer discharge limits including chemical oxygen demand (COD) (125 mg/L), total nitrogen (TN) (15 mg/L), and total phosphorus (TP) (2 mg/L). Phenols were close to or higher than the suggested water supply standard established by US EPA (1 mg/L). Leached carbon, nitrogen and phosphorus mainly came from the organic fraction of peats. Heating peats to 250 °C promoted the leaching of carbon-related pollutants, whereas heating to 300 °C enhanced the leaching of nutrients. Post-heated peats leached higher loads of pollutants in water than pre-heated peats, suggesting that fire-damaged boreal peats may be a critical but underappreciated source of water pollution. A simplified Partial Least Squares (PLS) model based on other easily measured parameters provided a simple method for determining the extent of COD and phenolic pollution in bulk water, relevant for water and wastewater treatment plants. Conclusions from this lab study indicate the need for field measurements of aquatic pollutants downstream of peatland watersheds post-fire as well as increased monitoring and treatment of potable water sources for leachable micropollutants in fire-dominated forested peatlands.
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Affiliation(s)
- Yichen Wu
- Department of Chemical Engineering, McMaster University, Hamilton, ON L8S 4L7, Canada
| | - Xuebin Xu
- State Key Laboratory of Soil and Sustainable Agriculture, Chinese Academy of Sciences, Institute of Soil Science, Nanjing, 210008, China
| | - Colin P R McCarter
- School of Earth, Environment & Society, McMaster University, Hamilton, ON L8S 4L7, Canada
| | - Nan Zhang
- Department of Chemical Engineering, McMaster University, Hamilton, ON L8S 4L7, Canada
| | - Mohamed A Ganzoury
- Department of Chemical Engineering, McMaster University, Hamilton, ON L8S 4L7, Canada
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6
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Sytiuk A, Céréghino R, Hamard S, Delarue F, Dorrepaal E, Küttim M, Lamentowicz M, Pourrut B, Robroek BJM, Tuittila E, Jassey VEJ. Biochemical traits enhance the trait concept in
Sphagnum
ecology. OIKOS 2022. [DOI: 10.1111/oik.09119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Anna Sytiuk
- Laboratoire Ecologie Fonctionnelle et Environnement, Univ. Paul Sabatier Toulouse 3, UPS, CNRS Toulouse France
| | - Regis Céréghino
- Laboratoire Ecologie Fonctionnelle et Environnement, Univ. Paul Sabatier Toulouse 3, UPS, CNRS Toulouse France
| | - Samuel Hamard
- Laboratoire Ecologie Fonctionnelle et Environnement, Univ. Paul Sabatier Toulouse 3, UPS, CNRS Toulouse France
| | | | - Ellen Dorrepaal
- Climate Impacts Research Centre, Dept of Ecology and Environmental Science, Umeå Univ. Abisko Sweden
| | - Martin Küttim
- Inst. of Ecology, School of Natural Sciences and Health, Tallinn Univ. Tallinn Estonia
| | - Mariusz Lamentowicz
- Climate Change Ecology Research Unit, Faculty of Geographical and Geological Sciences, Adam Mickiewicz Univ. in Poznań Poznań Poland
| | - Bertrand Pourrut
- Laboratoire Ecologie Fonctionnelle et Environnement, Univ. Paul Sabatier Toulouse 3, UPS, CNRS Toulouse France
| | - Bjorn J. M. Robroek
- Aquatic Ecology&Environmental Biology, Radboud Inst. for Biological and Environmental Sciences, Faculty of Science, Radboud Univ. Nijmegen Nijmegen the Netherlands
| | - Eeva‐Stiina Tuittila
- Biological Sciences, Faculty of Natural and Environmental Sciences, Inst. for Life Sciences, Univ. of Southampton Southampton UK
| | - Vincent E. J. Jassey
- Laboratoire Ecologie Fonctionnelle et Environnement, Univ. Paul Sabatier Toulouse 3, UPS, CNRS Toulouse France
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7
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Trifiró G, York R, Bell NGA. High-Resolution Molecular-Level Characterization of a Blanket Bog Peat Profile. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:660-671. [PMID: 34932324 DOI: 10.1021/acs.est.1c05837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
To understand peatland carbon-cycling processes ultimately requires the ability to track changes occurring on the molecular-level. In this study, we profile a peat core taken from the world's largest blanket bog, Flow Country, Scotland, using physicochemical properties, ATR-FTIR, solid/liquid-state NMR, and solid/liquid-state FT-ICR-MS. Air-dried peat and labile and recalcitrant peat extracts, including pore water dissolved organic matter (PW-DOM), are analyzed and the merits of each technique are discussed. Solid-state NMR demonstrated changing distribution of compound classes with core depth and water table, the latter not picked up by IR. Liquid-state NMR and MS both demonstrated variations in molecular composition along the core depth in all phases and extracts. Contrary to previous reports, the composition of PW-DOM varied with depth. Major compounds, some previously unreported, identified by 1D/2D NMR occurred throughout the core, suggesting the existence of hot spots of microbial activity/compound accumulation. Offering complementary views, the techniques provided evidence of gradual molecular level changes with age, zonation due to the water table, and hot spots due to microbial activity. This study provides new insights into the molecular signatures of peat layers and establishes the foundation for examining peat function and health at the molecular-level.
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Affiliation(s)
- Gianluca Trifiró
- University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
| | - Richard York
- University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
| | - Nicholle G A Bell
- University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
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8
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Etto RM, Jesus EDC, Cruz LM, Schneider BSF, Tomachewski D, Urrea-Valencia S, Gonçalves DRP, Galvão F, Ayub RA, Curcio GR, Steffens MBR, Galvão CW. Influence of environmental factors on the tropical peatlands diazotrophic communities from the Southern Brazilian Atlantic Rain Forest. Lett Appl Microbiol 2021; 74:543-554. [PMID: 34951701 DOI: 10.1111/lam.13638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 10/10/2021] [Accepted: 12/17/2021] [Indexed: 11/26/2022]
Abstract
The tropical peatlands of southern Brazil are essential for the maintenance of the Atlantic Rain Forest, one of the 25 hotspots of biodiversity in the world. Although diazotrophic microorganisms are essential for the maintenance of this nitrogen limited ecosystem, so far studies have focused only on microorganisms involved in the carbon cycle. In this work, peat samples were collected from three tropical peatland regions during dry and rainy seasons and their chemical and microbial characteristics were evaluated. Our results showed that the structure of the diazotrophic communities in the Brazilian tropical peatlands differs in the evaluated seasons. The abundance of the genus Bradyrhizobium showed to be affected by rainfall and peat pH. Despite the shifts of the nitrogen fixing population in the tropical peatland caused by seasonality it showed to be constantly dominated by α-Proteobacteria followed by Cyanobacteria. In addition, more than 50% of nifH gene sequences have not been classified, indicating the necessity for more studies in tropical peatland, since the reduction of N supply in the peatlands stimulates the recalcitrant organic matter decomposition performed by peatland microorganisms, influencing the C stock.
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Affiliation(s)
- Rafael Mazer Etto
- Microbial Molecular Biology Laboratory, State University of Ponta Grossa, CEP, 84030-900, Ponta Grossa - PR, Brazil
| | | | - Leonardo Magalhães Cruz
- Nucleus of Nitrogen Fixation, Federal University of Paraná, CEP, 81531-980, Curitiba - PR, Brazil
| | | | - Douglas Tomachewski
- Microbial Molecular Biology Laboratory, State University of Ponta Grossa, CEP, 84030-900, Ponta Grossa - PR, Brazil
| | - Salomé Urrea-Valencia
- Microbial Molecular Biology Laboratory, State University of Ponta Grossa, CEP, 84030-900, Ponta Grossa - PR, Brazil
| | - Daniel Ruiz Potma Gonçalves
- Microbial Molecular Biology Laboratory, State University of Ponta Grossa, CEP, 84030-900, Ponta Grossa - PR, Brazil
| | - Franklin Galvão
- Forest Ecology Laboratory, Universidade Federal do Paraná, CEP, 80210-170, Curitiba - PR, Brazil
| | - Ricardo Antônio Ayub
- Applied Biotechnology Laboratory, State University of Ponta Grossa, CEP, 84030-900, Ponta Grossa - PR, Brazil
| | | | | | - Carolina Weigert Galvão
- Microbial Molecular Biology Laboratory, State University of Ponta Grossa, CEP, 84030-900, Ponta Grossa - PR, Brazil
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9
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Shelley SJ, Brice DJ, Iversen CM, Kolka RK, Sebestyen SD, Griffiths NA. Deciphering the shifting role of intrinsic and extrinsic drivers on moss decomposition in peatlands over a 5‐year period. OIKOS 2021. [DOI: 10.1111/oik.08584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Sarah J. Shelley
- Oak Ridge Associated Univ. Oak Ridge TN USA
- Univ. of Tennessee Knoxville TN USA
- Climate Change Science Inst. and Environmental Sciences Division, Oak Ridge National Laboratory Oak Ridge TN USA
| | - Deanne J. Brice
- Climate Change Science Inst. and Environmental Sciences Division, Oak Ridge National Laboratory Oak Ridge TN USA
| | - Colleen M. Iversen
- Climate Change Science Inst. and Environmental Sciences Division, Oak Ridge National Laboratory Oak Ridge TN USA
| | - Randy K. Kolka
- Northern Research Station, USDA Forest Service Grand Rapids MN USA
| | | | - Natalie A. Griffiths
- Climate Change Science Inst. and Environmental Sciences Division, Oak Ridge National Laboratory Oak Ridge TN USA
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10
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Heffernan L, Jassey VEJ, Frederickson M, MacKenzie MD, Olefeldt D. Constraints on potential enzyme activities in thermokarst bogs: Implications for the carbon balance of peatlands following thaw. GLOBAL CHANGE BIOLOGY 2021; 27:4711-4726. [PMID: 34164885 DOI: 10.1111/gcb.15758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/04/2021] [Accepted: 06/15/2021] [Indexed: 06/13/2023]
Abstract
Northern peatlands store a globally significant amount of soil organic carbon, much of it found in rapidly thawing permafrost. Permafrost thaw in peatlands often leads to the development and expansion of thermokarst bogs, where microbial activity will determine the stability of the carbon storage and the release of greenhouse gases. In this study, we compared potential enzyme activities between young (thawed ~30 years ago) and mature (~200 years) thermokarst bogs, for both shallow and deep peat layers. We found very low potential enzyme activities in deep peat layers, with no differences between the young and mature bogs. Peat quality at depth was found to be highly humified (FTIR analysis) in both the young and mature bogs. This suggests that deep, old peat was largely stable following permafrost thaw, without a rapid pulse of decomposition during the young bog stage. For near-surface peat, we found significantly higher potential enzyme activities in the young bog than in the mature-associated with differences in peat quality derived from different Sphagnum species. A laboratory incubation of near-surface peat showed that differences in potential enzyme activity were primarily influenced by peat type rather than oxygen availability. This suggested that the young bog can have higher rates of near-surface decomposition despite being substantially wetter than the mature bog. Overall, our study shows that peat properties are the dominant constraint on potential enzyme activity and that peatland site development (successional pathways and permafrost history) through its influence on peat type and chemistry is likely to determine peat decomposition following permafrost thaw.
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Affiliation(s)
- Liam Heffernan
- Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada
| | - Vincent E J Jassey
- Laboratorie d'Ecologie Fonctionelle et Envrionnement, Université de Toulouse, CNRS, Toulouse, France
| | - Maya Frederickson
- Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada
| | - M Derek MacKenzie
- Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada
| | - David Olefeldt
- Department of Renewable Resources, University of Alberta, Edmonton, AB, Canada
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11
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Piatkowski BT, Yavitt JB, Turetsky MR, Shaw AJ. Natural selection on a carbon cycling trait drives ecosystem engineering by Sphagnum (peat moss). Proc Biol Sci 2021; 288:20210609. [PMID: 34403639 DOI: 10.1098/rspb.2021.0609] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sphagnum peat mosses have an extraordinary impact on the global carbon cycle as they control long-term carbon sequestration in boreal peatland ecosystems. Sphagnum species engineer peatlands, which harbour roughly a quarter of all terrestrial carbon, through peat accumulation by constructing their own niche that allows them to outcompete other plants. Interspecific variation in peat production, largely resulting from differences in tissue decomposability, is hypothesized to drive niche differentiation along microhabitat gradients thereby alleviating competitive pressure. However, little empirical evidence exists for the role of selection in the creation and maintenance of such gradients. In order to document how niche construction and differentiation evolved in Sphagnum, we quantified decomposability for 54 species under natural conditions and used phylogenetic comparative methods to model the evolution of this carbon cycling trait. We show that decomposability tracks the phylogenetic diversification of peat mosses, that natural selection favours different levels of decomposability corresponding to optimum niche and that divergence in this trait occurred early in the evolution of the genus prior to the divergence of most extant species. Our results demonstrate the evolution of ecosystem engineering via natural selection on an extended phenotype, of a fundamental ecosystem process, and one of the Earth's largest soil carbon pools.
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Affiliation(s)
| | - Joseph B Yavitt
- Department of Natural Resources, Cornell University, Ithaca, NY 14853, USA
| | - Merritt R Turetsky
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO 80309, USA
| | - A Jonathan Shaw
- Department of Biology, Duke University, Durham, NC 27708, USA
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12
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Väisänen M, Tuomi M, Bailey H, Welker JM. Plant and soil nitrogen in oligotrophic boreal forest habitats with varying moss depths: does exclusion of large grazers matter? Oecologia 2021; 196:839-849. [PMID: 34080051 PMCID: PMC8292301 DOI: 10.1007/s00442-021-04957-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 05/28/2021] [Indexed: 11/25/2022]
Abstract
The boreal forest consists of drier sunlit and moister-shaded habitats with varying moss abundance. Mosses control vascular plant-soil interactions, yet they all can also be altered by grazers. We determined how 2 decades of reindeer (Rangifer tarandus) exclusion affect feather moss (Pleurozium schreberi) depth, and the accompanying soil N dynamics (total and dissolvable inorganic N, δ15N), plant foliar N, and stable isotopes (δ15N, δ13C) in two contrasting habitats of an oligotrophic Scots pine forest. The study species were pine seedling (Pinus sylvestris L.), bilberry (Vaccinium myrtillus L.), lingonberry (V. vitis-idaea L.), and feather moss. Moss carpet was deeper in shaded than sunlit habitats and increased with grazer exclusion. Humus N content increased in the shade as did humus δ15N, which also increased due to exclusion in the sunlit habitats. Exclusion increased inorganic N concentration in the mineral soil. These soil responses were correlated with moss depth. Foliar chemistry varied due to habitat depending on species identity. Pine seedlings showed higher foliar N content and lower foliar δ15N in the shaded than in the sunlit habitats, while bilberry had both higher foliar N and δ15N in the shade. Thus, foliar δ15N values of co-existing species diverged in the shade indicating enhanced N partitioning. We conclude that despite strong grazing-induced shifts in mosses and subtler shifts in soil N, the N dynamics of vascular vegetation remain unchanged. These indicate that plant-soil interactions are resistant to shifts in grazing intensity, a pattern that appears to be common across boreal oligotrophic forests.
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Affiliation(s)
- Maria Väisänen
- Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland. .,Arctic Centre, University of Lapland, Rovaniemi, Finland.
| | - Maria Tuomi
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Hannah Bailey
- Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
| | - Jeffrey M Welker
- Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland.,Department of Biological Science, University of Alaska Anchorage, Anchorage, AK, USA.,UArctic, Rovaniemi, Finland
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Chen YD, Moles A, Bu ZJ, Zhang MM, Wang ZC, Zhao HY. Induced defense and its cost in two bryophyte species. AMERICAN JOURNAL OF BOTANY 2021; 108:777-787. [PMID: 33948954 DOI: 10.1002/ajb2.1654] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 12/22/2020] [Indexed: 06/12/2023]
Abstract
PREMISE Current knowledge about defense strategies in plants under herbivore pressure is predominantly based on vascular plants. Bryophytes are rarely consumed by herbivores since they have ample secondary metabolites. However, it is unknown whether bryophytes have induced defenses against herbivory and whether there is a trade-off between growth and defense in bryophytes. METHODS In an experiment with two peatland bryophytes, Sphagnum magellanicum Brid. and S. fuscum (Schimp.) H. Klinggr., two kinds of herbivory, clipping with scissors and grazing by mealworms (Tenebrio molitor L.) were simulated. At the end of the experiment, we measured growth traits, carbon-based defense compounds (total phenolics and cellulose) and storage compounds (total nonstructural carbohydrates) of these two Sphagnum species. RESULTS Grazing but not clipping increased total phenolics and C:N ratio and reduced biomass production and height increment. A negative relationship between biomass production and total phenolics was found in S. magellanicum but not in S. fuscum, indicating a growth-defense trade-off that is species-specific. Grazing reduced the sugar starch content of S. magellanicum and the sugar of S. fuscum. Either clipping or grazing had no effect on chlorophyll fluorescence (including actual and maximum photochemical efficiency of photosystem II) except that a significant effect of clipping on actual photochemical efficiency in S. fuscum was observed. CONCLUSIONS Our results suggest that Sphagnum can have induced defense against herbivory and that this defense can come at a cost of growth. These findings advance our knowledge about induced defense in bryophytes, the earliest land plants.
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Affiliation(s)
- Yong-Da Chen
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Renmin 5268, Changchun, 130024, China
| | - Angela Moles
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Kensington, NSW, 2052, Australia
| | - Zhao-Jun Bu
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Renmin 5268, Changchun, 130024, China
| | - Ming-Ming Zhang
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Renmin 5268, Changchun, 130024, China
| | - Zu-Cheng Wang
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Renmin 5268, Changchun, 130024, China
| | - Hong-Yan Zhao
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains, Ministry of Education, School of Geographical Sciences, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Renmin 5268, Changchun, 130024, China
- Jilin Provincial Key Laboratory for Wetland Ecological Processes and Environmental Change in the Changbai Mountains, Renmin 5268, Changchun, 130024, China
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14
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Hamard S, Robroek BJM, Allard PM, Signarbieux C, Zhou S, Saesong T, de Baaker F, Buttler A, Chiapusio G, Wolfender JL, Bragazza L, Jassey VEJ. Effects of Sphagnum Leachate on Competitive Sphagnum Microbiome Depend on Species and Time. Front Microbiol 2019; 10:2042. [PMID: 31555245 PMCID: PMC6742715 DOI: 10.3389/fmicb.2019.02042] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 08/20/2019] [Indexed: 12/03/2022] Open
Abstract
Plant specialized metabolites play an important role in soil carbon (C) and nutrient fluxes. Through anti-microbial effects, they can modulate microbial assemblages and associated microbial-driven processes, such as nutrient cycling, so to positively or negatively cascade on plant fitness. As such, plant specialized metabolites can be used as a tool to supplant competitors. These compounds are little studied in bryophytes. This is especially notable in peatlands where Sphagnum mosses can dominate the vegetation and show strong interspecific competition. Sphagnum mosses form carpets where diverse microbial communities live and play a crucial role in Sphagnum fitness by regulating C and nutrient cycling. Here, by means of a microcosm experiment, we assessed to what extent moss metabolites of two Sphagnum species (S. fallax and S. divinum) modulate the competitive Sphagnum microbiome, with particular focus on microbial respiration. Using a reciprocal leachate experiment, we found that interactions between Sphagnum leachates and microbiome are species-specific. We show that both Sphagnum leachates differed in compound richness and compound relative abundance, especially sphagnum acid derivates, and that they include microbial-related metabolites. The addition of S. divinum leachate on the S. fallax microbiome immediately reduced microbial respiration (−95%). Prolonged exposition of S. fallax microbiome to S. divinum leachate destabilized the food web structure due to a modulation of microbial abundance. In particular, leachate addition decreased the biomass of testate amoebae and rotifers but increased that of ciliates. These changes did not influence microbial CO2 respiration, suggesting that the structural plasticity of the food web leads to its functional resistance through the replacement of species that are functionally redundant. In contrast, S. fallax leachate neither affected S. divinum microbial respiration, nor microbial biomass. We, however, found that S. fallax leachate addition stabilized the food web structure associated to S. divinum by changing trophic interactions among species. The differences in allelopathic effects between both Sphagnum leachates might impact their competitiveness and affect species distribution at local scale. Our study further paves the way to better understand the role of moss and microbial specialized metabolites in peatland C dynamics.
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Affiliation(s)
- Samuel Hamard
- ECOLAB, Laboratoire d'Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse, France.,Laboratory of Ecological Systems (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering, Lausanne, Switzerland.,Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Lausanne, Switzerland.,Laboratoire de Géologie, UMR 8538, CNRS-ENS, Ecole Normale Supérieure, Paris, France
| | - Bjorn J M Robroek
- Laboratory of Ecological Systems (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering, Lausanne, Switzerland.,School of Biological Sciences, University of Southampton, Southampton, United Kingdom.,Aquatic Ecology and Environmental Biology Group, Faculty of Science, Institute for Water and Wetland Research, Radboud University, Nijmegen, Netherlands
| | - Pierre-Marie Allard
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Constant Signarbieux
- Laboratory of Ecological Systems (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering, Lausanne, Switzerland.,Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Lausanne, Switzerland
| | - Shuaizhen Zhou
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Tongchai Saesong
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland.,Department of Pharmaceutical Chemistry and Pharmacognosy, Faculty of Pharmaceutical Sciences and Center of Excellence for Innovation in Chemistry, Naresuan University, Phitsanulok, Thailand
| | - Flore de Baaker
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Alexandre Buttler
- Laboratory of Ecological Systems (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering, Lausanne, Switzerland.,Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Lausanne, Switzerland.,Laboratoire Chrono-Environnement, Université Bourgogne Franche Comté, UMR CNRS 6249 USC INRA, Montbéliard, France
| | - Geneviève Chiapusio
- Laboratoire Chrono-Environnement, Université Bourgogne Franche Comté, UMR CNRS 6249 USC INRA, Montbéliard, France.,Laboratoire Carrtel, Université Savoie Mont Blanc INRA 042, Domaine Universitaire Belledonne, Le Bourget-du-Lac, France
| | - Jean-Luc Wolfender
- School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland
| | - Luca Bragazza
- Laboratory of Ecological Systems (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering, Lausanne, Switzerland.,Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Lausanne, Switzerland.,Department of Life Science and Biotechnologies, University of Ferrara, Ferrara, Italy
| | - Vincent E J Jassey
- ECOLAB, Laboratoire d'Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse, France.,Laboratory of Ecological Systems (ECOS), Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering, Lausanne, Switzerland.,Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Lausanne, Switzerland
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