1
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Ding N, Ullah H, Yu G, He Y, Liu L, Xie Y, Shahab A, Lin H. Spatial dynamics of pH in the rhizosphere of Leersia hexandra Swartz at different chromium exposure. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 263:115380. [PMID: 37597293 DOI: 10.1016/j.ecoenv.2023.115380] [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: 12/14/2022] [Revised: 08/09/2023] [Accepted: 08/13/2023] [Indexed: 08/21/2023]
Abstract
The roots of hyperaccumulators can significantly alter soil pH and thus change the chromium (Cr) availability in the rhizosphere. The pH dynamics in the rhizosphere of Cr hyperaccumulator Leersia hexandra Swartz remains unknown. In this study, the spatial dynamics of pH in the rhizosphere of L. hexandra at different Cr exposure were examined using planar optode (PO). The effects of different Cr concentrations on the biomass, physiological parameters, and soil enzyme activity were investigated. The results showed that pH in the rhizosphere of L. hexandra was highly heterogeneous and followed the root shape. There were obvious soil acidification in all groups and the average pH values in the control, Cr50, and Cr100 groups decreased by 0.26, 0.27, and 0.35 pH unit, respectively. At a certain concentration (50 mg kg-1), Cr significantly increased the plant height and biomass of L. hexandra compared to the control (p < 0.05). The concentrations of chlorophyll a, chlorophyll b, and total chlorophyll in the leaves increased with increasing Cr concentrations. The acid phosphatase, urease, and catalase activities in the rhizosphere were higher than those in the bulk soil. These results provide new insights into elucidating the hyperaccumulating mechanism of Cr and improving the phytoremediation efficiency.
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Affiliation(s)
- Na Ding
- College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China.
| | - Habib Ullah
- Innovation Center of Yangtze River Delta, Zhejiang University, Zhejiang 311400, China.
| | - Guo Yu
- College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China.
| | - Yao He
- College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China.
| | - Liheng Liu
- College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China.
| | - Yiruiwen Xie
- Department of Architecture and Environmental Engineering, Taiyuan University, Taiyuan, China.
| | - Asfandyar Shahab
- College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China.
| | - Hua Lin
- College of Environmental Science and Engineering, Guilin University of Technology, Guilin, China.
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2
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Pan B, Liu S, Wang Y, Li D, Li M. FT-ICR-MS combined with fluorescent spectroscopy reveals the driving mechanism of the spatial variation in molecular composition of DOM in 22 plateau lakes. ENVIRONMENTAL RESEARCH 2023:116272. [PMID: 37276978 DOI: 10.1016/j.envres.2023.116272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 05/21/2023] [Accepted: 05/27/2023] [Indexed: 06/07/2023]
Abstract
Dissolved organic matter (DOM) is the largest carbon pool and directly affects the biogeochemistry in lakes. In the current study, fourier transform ion cyclotron mass spectrometry (FT-ICR-MS) combined with fluorescent spectroscopy was used to assess the molecular composition and driving mechanism of DOM in 22 plateau lakes in Mongolia Plateau Lakes Region (MLR), Qinghai Plateau Lakes Region (QLR) and Tibet Plateau Lakes Region (TLR) of China. The limnic dissolved organic carbon (DOC) content ranged from 3.93 to 280.8 mg L-1 and the values in MLR and TLR were significantly higher than that in QLR. The content of lignin was the highest in each lake and showed a gradually decreasing trend from MLR to TLR. Random forest model and structural equation model implied that altitude played an important role in lignin degradation while the contents of total nitrogen (TN) and chlorophyll a (Chl-a) have a great influence on the increase of DOM Shannon index. Our results also suggested that the inspissation of DOC and the promoted endogenous DOM production caused by the inspissation of nutrient resulted in a positive relationship between limnic DOC content and limnic factors such as salinity, alkalinity and nutrient concentration. From MLR to QLR and TLR, the molecular weight and the number of double bonds gradually decreased but the humification index (HIX) also decreased. In addition, from the MLR to the TLR, the proportion of lignin gradually decreased, while the proportion of lipid gradually increased. Both above results suggested that photodegradation was dominated in lakes of TLR, while microbial degradation was dominated in lakes of MLR.
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Affiliation(s)
- Baozhu Pan
- State Key Laboratory of Eco-hydraulic in Northwest Arid Region of China, Xi'an University of Technology, Xi'an, 710048, Shaanxi, PR China
| | - Siwan Liu
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, PR China
| | - Yeyong Wang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, PR China
| | - Dianbao Li
- State Key Laboratory of Eco-hydraulic in Northwest Arid Region of China, Xi'an University of Technology, Xi'an, 710048, Shaanxi, PR China
| | - Ming Li
- College of Natural Resources and Environment, Northwest A&F University, Yangling, 712100, Shaanxi, PR China.
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3
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LaFond-Hudson S, Sulman B. Modeling strategies and data needs for representing coastal wetland vegetation in land surface models. THE NEW PHYTOLOGIST 2023; 238:938-951. [PMID: 36683447 DOI: 10.1111/nph.18760] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Vegetated coastal ecosystems sequester carbon rapidly relative to terrestrial ecosystems. Coastal wetlands are poorly represented in land surface models, but work is underway to improve process-based, predictive modeling of these ecosystems. Here, we identify guiding questions, potential simulations, and data needs to make progress in improving representation of vegetation in terrestrial-aquatic interfaces, with a focus on coastal and estuarine ecosystems. We synthesize relevant plant traits and environmental controls on vegetation that influence carbon cycling in coastal ecosystems. We propose that models include separate plant functional types (PFTs) for mangroves, graminoid salt marshes, and succulent salt marshes to adequately represent the variation in aboveground and belowground productivity between common coastal wetland vegetation types. We also discuss the drivers and carbon storage consequences of shifts in dominant PFTs. We suggest several potential approaches to represent the diversity in vegetation tolerance and adaptations to fluctuations in salinity and water level, which drive key gradients in coastal wetland ecosystems. Finally, we discuss data needs for parameterizing and evaluating model implementations of coastal wetland vegetation types and function.
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Affiliation(s)
- Sophia LaFond-Hudson
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN, 37917, USA
| | - Benjamin Sulman
- Environmental Sciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN, 37917, USA
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4
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Bernal B, Kim S, Mozdzer TJ. Species shifts induce soil organic matter priming and changes in microbial communities. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 859:159956. [PMID: 36351499 DOI: 10.1016/j.scitotenv.2022.159956] [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: 08/14/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 06/16/2023]
Abstract
Invasion of plant species with functional traits that influences the rhizosphere can have significant effects on soil organic matter (SOM) dynamics if the invasive species stimulates soil microbial communities with, for example, an enhanced supply of labile carbon and oxygen. We evaluated these effects along a Phragmites invasion chronosequence spanning over 40 years. Using a δ13C and δ15N enriched substrate, we separated SOM-derived and substrate-derived carbon (C) and nitrogen (N) mineralization in surface (top 15 cm), shallow (30-45 cm), and deep (65-80 cm) soils collected from established, newly invaded, and native plant communities. We found all soils were susceptible to SOM priming, but priming profiles differed between vegetation communities, being highest at the surface in native assemblage soils, whereas highest at depth under invasive plants. Changes in functional microbial community composition at depth in Phragmites soils, evidenced by an increase in relative fungal laccase abundance, explained the SOM priming in these deep invaded soils. Our results show that invasive Phragmites maintains a microbial community at depth able to degrade SOM faster than that under native vegetation, evidencing that plant species shifts can fundamentally change soil biogeochemistry, altering element cycling and decreasing SOM residence time. Furthermore, our experimental design allowed to quantify real-time SOM-C and SOM-N gross mineralization, resulting in a new model relating C and N mineralization in these wetland soils and providing new insights on how SOM decomposition impacts N availability and cycling across wetland N pools.
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Affiliation(s)
- Blanca Bernal
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD 21037, United States of America; GreenCollar US, Inc. International Programme, Chicago, IL 60611, United States of America.
| | - Sunghyun Kim
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD 21037, United States of America; Brain Busan 21 Plus Program, Catholic University of Pusan, Busan 46252, Republic of Korea
| | - Thomas J Mozdzer
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD 21037, United States of America; Bryn Mawr College, Department of Biology, 101 N Merion Ave, Bryn Mawr, PA 19010, United States of America
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5
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Wang H, Dai Z, Trettin CC, Krauss KW, Noe GB, Burton AJ, Stagg CL, Ward EJ. Modeling impacts of drought-induced salinity intrusion on carbon dynamics in tidal freshwater forested wetlands. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2022; 32:e2700. [PMID: 35751513 DOI: 10.1002/eap.2700] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 04/21/2022] [Accepted: 05/09/2022] [Indexed: 06/15/2023]
Abstract
Tidal freshwater forested wetlands (TFFW) provide critical ecosystem services including an essential habitat for a variety of wildlife species and significant carbon sinks for atmospheric carbon dioxide. However, large uncertainties remain concerning the impacts of climate change on the magnitude and variability of carbon fluxes and storage across a range of TFFW. In this study, we developed a process-driven Tidal Freshwater Wetlands DeNitrification-DeComposition model (TFW-DNDC) that has integrated new features, such as soil salinity effects on plant productivity and soil organic matter decomposition to explore carbon dynamics in the TFFW in response to drought-induced saltwater intrusion. Eight sites along the floodplains of the Waccamaw River (USA) and the Savannah River (USA) were selected to represent the TFFW transition from healthy to moderately and highly salt-impacted forests, and eventually to oligohaline marshes. The TFW-DNDC was calibrated and validated using field observed annual litterfall, stem growth, root growth, soil heterotrophic respiration, and soil organic carbon storage. Analyses indicate that plant productivity and soil carbon sequestration in TFFW could change substantially in response to increased soil pore water salinity and reduced soil water table due to drought, but in interactive ways dependent on the river simulated. These responses are variable due to nonlinear relationships between carbon cycling processes and environmental drivers. Plant productivity, plant respiration, soil organic carbon sequestration rate, and storage in the highly salt-impacted forest sites decreased significantly under drought conditions compared with normal conditions. Considering the high likelihood of healthy and moderately salt-impacted forests becoming highly salt-impacted forests under future climate change and sea-level rise, it is very likely that the TFFW will lose their capacity as carbon sinks without up-slope migration.
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Affiliation(s)
- Hongqing Wang
- U.S. Geological Survey, Wetland and Aquatic Research Center, Baton Rouge, Louisiana, USA
| | - Zhaohua Dai
- Center for Forested Wetlands Research, USDA Forest Service, Cordesville, South Carolina, USA
- Michigan Technological University, College of Forest Resources and Environmental Science, Houghton, Michigan, USA
| | - Carl C Trettin
- Center for Forested Wetlands Research, USDA Forest Service, Cordesville, South Carolina, USA
| | - Ken W Krauss
- U.S. Geological Survey, Wetland and Aquatic Research Center, Lafayette, Louisiana, USA
| | - Gregory B Noe
- U.S. Geological Survey, Florence Bascom Geoscience Center, Reston, Virginia, USA
| | - Andrew J Burton
- Michigan Technological University, College of Forest Resources and Environmental Science, Houghton, Michigan, USA
| | - Camille L Stagg
- U.S. Geological Survey, Wetland and Aquatic Research Center, Lafayette, Louisiana, USA
| | - Eric J Ward
- U.S. Geological Survey, Wetland and Aquatic Research Center, Lafayette, Louisiana, USA
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6
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Lumibao CY, Torres Martínez L, Megonigal JP, Van Bael SA, Blum MJ. Microbial mediation of salinity stress response varies by plant genotype and provenance over time. Mol Ecol 2022; 31:4571-4585. [DOI: 10.1111/mec.16603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 06/30/2022] [Accepted: 07/04/2022] [Indexed: 11/28/2022]
Affiliation(s)
- Candice Y. Lumibao
- University of Tennessee Department of Ecology & Evolutionary Biology Knoxville TN USA
- Texas A&M University – Corpus Christi, Department of Life Sciences Corpus Christi Texas USA
| | | | | | - Sunshine A. Van Bael
- Tulane University Department of Ecology & Evolutionary Biology New Orleans LA USA
| | - Michael J. Blum
- University of Tennessee Department of Ecology & Evolutionary Biology Knoxville TN USA
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7
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Lane SL. Using marsh organs to test seed recruitment in tidal freshwater marshes. APPLICATIONS IN PLANT SCIENCES 2022; 10:e11474. [PMID: 36034188 PMCID: PMC9400397 DOI: 10.1002/aps3.11474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/05/2021] [Accepted: 12/23/2021] [Indexed: 06/15/2023]
Abstract
Premise Seed recruitment niches along estuarine elevation gradients are seldom experimentally field-tested under tidal regimes of the Pacific Northwest of North America. Addressing this knowledge gap is important to better understand estuary restoration and plant community response to sea level rise. Methods Germination was tested in marsh organ mesocosms across an elevation gradient (0.5-1.7 m above mean sea level). Seeds were sown on sterile peat moss, and the tops of pipes were secured with horticultural "frost cloth" to ensure no experimental seeds were washed out and no new seeds were introduced. The trials tested artificial and overwinter chilling regimes, as well as the presence and/or absence of a near-neighbor transplant. Results Carex lyngbyei had significant elevation-driven germination after overwinter and artificial chilling. Schoenoplectus tabernaemontani had near-significant germination across elevation after overwinter chilling, and germination in the absence of competition was significantly greater than with a near-neighbor transplant. Discussion Carex lyngbyei had the highest germination rate at higher elevations, which suggests restricted seed recruitment potential and required clonal expansion to extend into lower marsh elevations. Identifying species-specific recruitment niches provides insight for restoration opportunities or invasive species monitoring, as well as for estuary migration under sea level rise.
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Affiliation(s)
- Stefanie L. Lane
- Department of Forest and Conservation SciencesThe University of British ColumbiaVancouverBritish ColumbiaCanada
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8
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Smith AJ, Noyce GL, Megonigal JP, Guntenspergen GR, Kirwan ML. Temperature optimum for marsh resilience and carbon accumulation revealed in a whole-ecosystem warming experiment. GLOBAL CHANGE BIOLOGY 2022; 28:3236-3245. [PMID: 35239211 DOI: 10.1111/gcb.16149] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/02/2022] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Abstract
Coastal marshes are globally important, carbon dense ecosystems simultaneously maintained and threatened by sea-level rise. Warming temperatures may increase wetland plant productivity and organic matter accumulation, but temperature-modulated feedbacks between productivity and decomposition make it difficult to assess how wetlands and their thick, organic-rich soils will respond to climate warming. Here, we actively increased aboveground plant-surface and belowground soil temperatures in two marsh plant communities, and found that a moderate amount of warming (1.7°C above ambient temperatures) consistently maximized root growth, marsh elevation gain, and belowground carbon accumulation. Marsh elevation loss observed at higher temperatures was associated with increased carbon mineralization and increased microtopographic heterogeneity, a potential early warning signal of marsh drowning. Maximized elevation and belowground carbon accumulation for moderate warming scenarios uniquely suggest linkages between metabolic theory of individuals and landscape-scale ecosystem resilience and function, but our work indicates nonpermanent benefits as global temperatures continue to rise.
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Affiliation(s)
- Alexander J Smith
- Virginia Institute of Marine Science, William & Mary, Gloucester Point, Virginia, USA
| | | | | | | | - Matthew L Kirwan
- Virginia Institute of Marine Science, William & Mary, Gloucester Point, Virginia, USA
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9
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Kim J, Heo YM, Yun J, Lee H, Kim JJ, Kang H. Changes in Archaeal Community and Activity by the Invasion of Spartina anglica Along Soil Depth Profiles of a Coastal Wetland. MICROBIAL ECOLOGY 2022; 83:436-446. [PMID: 34003315 DOI: 10.1007/s00248-021-01770-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/05/2021] [Indexed: 06/12/2023]
Abstract
Invasion of Spartina spp. in tidal salt marshes may affect the function and characteristics of the ecosystem. Previous studies reported that the invasion alters biogeochemical and microbial processes in marsh ecosystems, yet our knowledge of changing archaeal community due to the invasion is still limited, whereas archaeal communities play a pivotal role in biogeochemical cycles within highly reduced marsh soils. In this study, we aimed to illustrate the influences of the Spartina anglica invasion on soil archaeal community and the depth profile of the influences. The relative abundance of archaeal phyla demonstrated that the invasion substantially shifted the characteristics of tidal salt marsh from marine to terrestrial soil only in surface layer, while the influences indirectly propagated to the deeper soil layer. In particular, two archaeal phyla, Asgardaeota and Diapherotrites, were strongly influenced by the invasion, indicating a shift from marine to terrestrial archaeal communities. The shifts in soil characteristics spread to the deeper soil layer that results in indirect propagation of the influences of the invasion down to the deeper soil, which was underestimated in previous studies. The changes in the concentration of dissolved organic carbon and salinity were the substantial regulating factors for that. Therefore, changes in biogeochemical and microbial characteristics in the deep soil layer, which is below the root zone of the invasive plant, should be accounted for a more accurate illustration of the consequences of the invasion.
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Affiliation(s)
- Jinhyun Kim
- School of Civil and Environmental Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Young Mok Heo
- College of Life Sciences & Biotechnology, Korea University, Seoul, 02841, Republic of Korea
| | - Jeongeun Yun
- School of Civil and Environmental Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Hanbyul Lee
- College of Life Sciences & Biotechnology, Korea University, Seoul, 02841, Republic of Korea
| | - Jae-Jin Kim
- College of Life Sciences & Biotechnology, Korea University, Seoul, 02841, Republic of Korea.
- Division of Environmental Science & Ecological Engineering, Korea University, Seoul, 02841, Republic of Korea.
| | - Hojeong Kang
- School of Civil and Environmental Engineering, Yonsei University, Seoul, 03722, Republic of Korea.
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10
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Ren L, Jensen K, Porada P, Mueller P. Biota-mediated carbon cycling-A synthesis of biotic-interaction controls on blue carbon. Ecol Lett 2022; 25:521-540. [PMID: 35006633 DOI: 10.1111/ele.13940] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/03/2021] [Accepted: 11/02/2021] [Indexed: 01/22/2023]
Abstract
Research into biotic interactions has been a core theme of ecology for over a century. However, despite the obvious role that biota play in the global carbon cycle, the effects of biotic interactions on carbon pools and fluxes are poorly understood. Here we develop a conceptual framework that illustrates the importance of biotic interactions in regulating carbon cycling based on a literature review and a quantitative synthesis by means of meta-analysis. Our study focuses on blue carbon ecosystems-vegetated coastal ecosystems that function as the most effective long-term CO2 sinks of the biosphere. We demonstrate that a multitude of mutualistic, competitive and consumer-resource interactions between plants, animals and microbiota exert strong effects on carbon cycling across various spatial scales ranging from the rhizosphere to the landscape scale. Climate change-sensitive abiotic factors modulate the strength of biotic-interaction effects on carbon fluxes, suggesting that the importance of biota-mediated carbon cycling will change under future climatic conditions. Strong effects of biotic interactions on carbon cycling imply that biosphere-climate feedbacks may not be sufficiently represented in current Earth system models. Inclusion of new functional groups in these models, and new approaches to simplify species interactions, may thus improve the predictions of biotic effects on the global climate.
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Affiliation(s)
- Linjing Ren
- Institute of Plant Science and Microbiology, Universität Hamburg, Hamburg, Germany.,State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, P. R. China
| | - Kai Jensen
- Institute of Plant Science and Microbiology, Universität Hamburg, Hamburg, Germany
| | - Philipp Porada
- Institute of Plant Science and Microbiology, Universität Hamburg, Hamburg, Germany
| | - Peter Mueller
- Institute of Plant Science and Microbiology, Universität Hamburg, Hamburg, Germany.,Smithsonian Environmental Research Center, Edgewater, Maryland, USA
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11
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Keshta AE, Yarwood SA, Baldwin AH. A new in situ method showed greater persistence of added soil organic matter in natural than restored wetlands. Restor Ecol 2021. [DOI: 10.1111/rec.13437] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Amr E. Keshta
- Department of Environmental Science and Technology University of Maryland, Animal Science Building College Park MD 20742 U.S.A
- Botany Department, College of Science Tanta University Tanta 31512 Egypt
| | - Stephanie A. Yarwood
- Department of Environmental Science and Technology University of Maryland, Animal Science Building College Park MD 20742 U.S.A
| | - Andrew H. Baldwin
- Department of Environmental Science and Technology University of Maryland, Animal Science Building College Park MD 20742 U.S.A
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12
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Blum MJ, Saunders CJ, McLachlan JS, Summers J, Craft C, Herrick JD. A century-long record of plant evolution reconstructed from a coastal marsh seed bank. Evol Lett 2021; 5:422-431. [PMID: 34367666 PMCID: PMC8327947 DOI: 10.1002/evl3.242] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 04/30/2021] [Accepted: 05/20/2021] [Indexed: 11/12/2022] Open
Abstract
Evidence is mounting that climate-driven shifts in environmental conditions can elicit organismal evolution, yet there are sparingly few long-term records that document the tempo and progression of responses, particularly for plants capable of transforming ecosystems. In this study, we "resurrected" cohorts of a foundational coastal marsh sedge (Schoenoplectus americanus) from a time-stratified seed bank to reconstruct a century-long record of heritable variation in response to salinity exposure. Common-garden experiments revealed that S. americanus exhibits heritable variation in phenotypic traits and biomass-based measures of salinity tolerance. We found that responses to salinity exposure differed among the revived cohorts, with plants from the early 20th century exhibiting greater salinity tolerance than those from the mid to late 20th century. Fluctuations in salinity tolerance could reflect stochastic variation but a congruent record of genotypic variation points to the alternative possibility that the loss and gain in functionality are driven by selection, with comparisons to historical rainfall and paleosalinity records suggesting that selective pressures vary according to shifting estuarine conditions. Because salinity tolerance in S. americanus is tightly coupled to primary productivity and other vital ecosystem attributes, these findings indicate that organismal evolution merits further consideration as a factor shaping coastal marsh responses to climate change.
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Affiliation(s)
- Michael J. Blum
- Department of Ecology & Evolutionary BiologyUniversity of TennesseeKnoxvilleTennessee37996
| | - Colin J. Saunders
- Southeast Environmental Research CenterFlorida International UniversityMiamiFlorida33199
| | - Jason S. McLachlan
- Department of Biological SciencesUniversity of Notre DameSouth BendIndiana46556
| | - Jennifer Summers
- Department of Ecology & Evolutionary BiologyUniversity of TennesseeKnoxvilleTennessee37996
| | - Christopher Craft
- School of Public and Environmental AffairsIndiana UniversityBloomingtonIndiana47405
| | - Jeffrey D. Herrick
- U.S Environmental Protection AgencyOffice of Research and DevelopmentResearch Triangle ParkNorth Carolina27711
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13
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O'Meara TA, Thornton PE, Ricciuto DM, Noyce GL, Rich RL, Megonigal J. Considering coasts: Adapting terrestrial models to characterize coastal wetland ecosystems. Ecol Modell 2021. [DOI: 10.1016/j.ecolmodel.2021.109561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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14
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Li B, Li P, Yang X, Xiao H, Xu M, Liu G. Land‐use conversion changes deep soil organic carbon stock in the Chinese Loess Plateau. LAND DEGRADATION & DEVELOPMENT 2021; 32:505-517. [DOI: 10.1002/ldr.3644] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 04/29/2020] [Indexed: 09/01/2023]
Abstract
AbstractLand‐use change is a key factor driving changes in soil organic carbon (SOC) sequestration worldwide. However, the changes in deep (>100 cm depth) SOC stock following land‐use conversion have not been fully elucidated. In this study, to determine the changes in deep SOC stock (to a depth of 400 cm) resulting from conversion of cropland to woodland, shrubland and grassland on the Chinese Loess Plateau, 469 observations from peer‐reviewed publications and original measured data were synthesised. The results were as follows: (a) SOC stock increased significantly at 0–100 and 100–200 cm layers regardless of land‐use conversion types. (b) Carbon loss occurred in the 200–400 cm layers due to land‐use conversion. (c) Changes in SOC stock varied with restoration age, except for conversion of cropland to grassland. Specifically, SOC stock increased with restoration age in the upper 200 cm layers, whereas that in the 200–400 cm layers first increased and then decreased in the middle to later stages under conversion to woodland and shrubland. (d) Initial SOC stock and rainfall zones had significant effects on the changes of deep SOC stock. (e) Furthermore, an accumulation of 1 Mg ha−1 in the upper 100 cm was associated with an approximately 0.45 Mg ha−1 increase in the 100–400 cm soil layers. These results indicate that land‐use conversion, particularly conversion of cropland to woodland, changes deep (>100 cm) SOC stock, and restoration age should be taken into consideration when assessing deep carbon sequestration.
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Affiliation(s)
- Bin‐Bin Li
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Yangling PR China
- University of Chinese Academy of Sciences Beijing PR China
| | - Pan‐Pan Li
- Institute of Soil and Water Conservation Northwest A & F University Yangling PR China
| | - Xiao‐Mei Yang
- College of Natural Resources and Environment Northwest A & F University Yangling PR China
| | - Hai‐Bing Xiao
- College of Resources and Environment Huazhong Agricultural University Wuhan PR China
| | - Ming‐Xiang Xu
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Yangling PR China
- Institute of Soil and Water Conservation Northwest A & F University Yangling PR China
| | - Guo‐Bin Liu
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation Chinese Academy of Sciences and Ministry of Water Resources Yangling PR China
- Institute of Soil and Water Conservation Northwest A & F University Yangling PR China
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15
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Mueller P, Mozdzer TJ, Langley JA, Aoki LR, Noyce GL, Megonigal JP. Plant species determine tidal wetland methane response to sea level rise. Nat Commun 2020; 11:5154. [PMID: 33056993 PMCID: PMC7560622 DOI: 10.1038/s41467-020-18763-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/01/2020] [Indexed: 11/23/2022] Open
Abstract
Blue carbon (C) ecosystems are among the most effective C sinks of the biosphere, but methane (CH4) emissions can offset their climate cooling effect. Drivers of CH4 emissions from blue C ecosystems and effects of global change are poorly understood. Here we test for the effects of sea level rise (SLR) and its interactions with elevated atmospheric CO2, eutrophication, and plant community composition on CH4 emissions from an estuarine tidal wetland. Changes in CH4 emissions with SLR are primarily mediated by shifts in plant community composition and associated plant traits that determine both the direction and magnitude of SLR effects on CH4 emissions. We furthermore show strong stimulation of CH4 emissions by elevated atmospheric CO2, whereas effects of eutrophication are not significant. Overall, our findings demonstrate a high sensitivity of CH4 emissions to global change with important implications for modeling greenhouse-gas dynamics of blue C ecosystems.
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Affiliation(s)
- Peter Mueller
- Smithsonian Environmental Research Center, Edgewater, MD, 21037, USA.
- Institute of Soil Science, Center for Earth System Research and Sustainability (CEN), Universität Hamburg, 20146, Hamburg, Germany.
| | - Thomas J Mozdzer
- Department of Biology, Bryn Mawr College, Bryn Mawr, PA, 19010, USA
| | - J Adam Langley
- Department of Biology, Center for Biodiversity and Ecosystem Stewardship, Villanova University, Villanova, PA, 19003, USA
| | - Lillian R Aoki
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Genevieve L Noyce
- Smithsonian Environmental Research Center, Edgewater, MD, 21037, USA
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16
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Tang H, Nolte S, Jensen K, Yang Z, Wu J, Mueller P. Grazing mediates soil microbial activity and litter decomposition in salt marshes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 720:137559. [PMID: 32325578 DOI: 10.1016/j.scitotenv.2020.137559] [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: 11/29/2019] [Revised: 02/11/2020] [Accepted: 02/24/2020] [Indexed: 06/11/2023]
Abstract
Salt marshes contribute to climate change mitigation because of their great capacity to store organic matter (OM) in soils. Most of the research regarding OM turnover in salt marshes in times of global change focuses on effects of rising temperature and accelerated sea-level rise, while effects of land-use change have gained little attention. The present work investigates the mechanisms by which livestock grazing can affect OM decomposition in salt marsh soils. In a grazing exclusion experiment at the mouth of the Yangtze estuary, China, we assessed soil microbial exo-enzyme activity (EEA) to gain insight into the microbial carbon (C) and nitrogen (N) demand. Additionally, we studied the decomposition of plant litter in soil using the Tea Bag Index (TBI), a widely used standardized litter bag assay to fingerprint soil decomposition dynamics. Based on EEAs, grazing markedly reduced microbial C acquisition, whereas microbial N acquisition was strongly increased. These opposing grazing effects were also evident in the decomposition of standardized plant litter: The decomposition rate constant (k) and the stabilization (S) of litter were not inversely related, as would be expected, but instead both were reduced by livestock grazing. Our data suggest that gazing effects on EEAs and litter decomposition can just partly be explained by grazing-driven soil compaction and resulting lower oxygen availability, which has previously been hypothesized as a main pathway by which grazing can reduce microbial activity in wetland soils. Instead, grazing effects on microbial nutrient demand occurs to be an at least equally important control on soil decomposition processes.
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Affiliation(s)
- H Tang
- Plant Ecology, Institute of Plant Science and Microbiology, Universität Hamburg, Ohnhorststr. 18, 22609 Hamburg, Germany
| | - S Nolte
- Plant Ecology, Institute of Plant Science and Microbiology, Universität Hamburg, Ohnhorststr. 18, 22609 Hamburg, Germany; School of Environmental Sciences, University of East Anglia, Norwich Research Park, NR4 7TJ Norwich, UK; Centre for Environment, Fisheries and Aquaculture Science, Pakefield Rd, Lowestoft, UK
| | - K Jensen
- Plant Ecology, Institute of Plant Science and Microbiology, Universität Hamburg, Ohnhorststr. 18, 22609 Hamburg, Germany
| | - Z Yang
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Coastal Ecosystems Research Station of Yangtze River Estuary, Institute of Biodiversity Science and Institute of Eco-Chongming, School of Life Sciences, Fudan University, 200433 Shanghai, PR China; Liupanshui Normal University, 553000 Liupanshui, PR China
| | - J Wu
- Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Coastal Ecosystems Research Station of Yangtze River Estuary, Institute of Biodiversity Science and Institute of Eco-Chongming, School of Life Sciences, Fudan University, 200433 Shanghai, PR China
| | - P Mueller
- Smithsonian Environmental Research Center, Contees Wharf Rd 647, MD 21037, Edgewater, United States.
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17
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Liu Y, Luo M, Ye R, Huang J, Xiao L, Hu Q, Zhu A, Tong C. Impacts of the rhizosphere effect and plant species on organic carbon mineralization rates and pathways, and bacterial community composition in a tidal marsh. FEMS Microbiol Ecol 2020; 95:5538758. [PMID: 31344237 DOI: 10.1093/femsec/fiz120] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 07/18/2019] [Indexed: 11/13/2022] Open
Abstract
Despite the growing recognition regarding the carbon cycle in the rhizosphere of upland ecosystems, little is known regarding the rhizosphere effect on soil organic carbon (SOC) mineralization in tidal marsh soils. In the current study, in situ rhizobox experiments (including rhizosphere and inner and outer bulk soil) were conducted in an estuarine tidal marsh. Our results showed that a higher abundance of total bacteria, Geobacter, dsrA and mcrA and lower α-diversity were observed in the rhizosphere relative to the bulk soil. Rhizosphere effects shifted the partition of terminal metabolic pathways from sulfate reduction in the bulk soil to the co-dominance of microbial Fe(III) and sulfate reduction in the rhizosphere. Although the rhizosphere effect promoted the rates of three terminal metabolic pathways, it showed greater preference towards microbial Fe(III) reduction in the tidal marsh soils. Plant species had little impact on the partitioning of terminal metabolic pathways, but did affect the potential of total SOC mineralization together with the abundance and diversity of total bacteria. Both the rhizosphere effect and plant species influenced the bacterial community composition in the tidal marsh soils; however, plant species had a less pronounced impact on the bacterial community compared with that of the rhizosphere effect.
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Affiliation(s)
- Yuxiu Liu
- Key Laboratory of Humid Subtropical Eco-Geographical Process, Ministry of Education, Fujian Normal University, Fuzhou 350007, China
| | - Min Luo
- Key Laboratory of Humid Subtropical Eco-Geographical Process, Ministry of Education, Fujian Normal University, Fuzhou 350007, China.,School of Environment and Resource, Fuzhou University, Fuzhou 350116, China
| | - Rongzhong Ye
- Pee Dee Research & Education Centers, Clemson University, Florence, SC 29506, USA
| | - Jiafang Huang
- Key Laboratory of Humid Subtropical Eco-Geographical Process, Ministry of Education, Fujian Normal University, Fuzhou 350007, China
| | - Leilei Xiao
- Key Laboratory of Coastal Biology and Biological Resources Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Qikai Hu
- Key Laboratory of Humid Subtropical Eco-Geographical Process, Ministry of Education, Fujian Normal University, Fuzhou 350007, China.,School of Environment and Resource, Fuzhou University, Fuzhou 350116, China
| | - Aijv Zhu
- Key Laboratory of Humid Subtropical Eco-Geographical Process, Ministry of Education, Fujian Normal University, Fuzhou 350007, China
| | - Chuan Tong
- Key Laboratory of Humid Subtropical Eco-Geographical Process, Ministry of Education, Fujian Normal University, Fuzhou 350007, China
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18
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Dinter T, Geihser S, Gube M, Daniel R, Kuzyakov Y. Impact of sea level change on coastal soil organic matter, priming effects and prokaryotic community assembly. FEMS Microbiol Ecol 2020; 95:5551479. [PMID: 31425573 DOI: 10.1093/femsec/fiz129] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 08/18/2019] [Indexed: 01/09/2023] Open
Abstract
Salt marshes are coastal areas storing high amounts of soil organic matter (SOM) while simultaneously being prone to tidal changes. Here, SOM-decomposition and accompanied priming effects (PE), which describe interactions between labile and old SOM, were studied under controlled flooding conditions. Soil samples from two Wadden Sea salt marsh zones, pioneer (Pio), flooded two times/day, and lower salt marsh (Low), flooded ∼eight times/month, were measured for 56 days concerning CO2-efflux and prokaryotic community shifts during three different inundation-treatments: total-drained (Drained), all-time-flooded (Waterlogged) or temporal-flooding (Tidal). Priming was induced by 14C-glucose addition. CO2-efflux from soil followed Low>Pio and Tidal>Drained>Waterlogged, likely due to O2-depletion and moisture maintenance, two key factors governed by tidal inundation with regard to SOM mineralisation. PEs in both zones were positive (Drained) or absent (Waterlogged, Tidal), presumably as a result of prokaryotes switching from production of extracellular enzymes to direct incorporation of labile C. A doubled amount of prokaryotic biomass in Low compared to Pio probably induced higher chances of cometabolic effects and higher PE. 16S-rRNA-gene-amplicon-based analysis revealed differences in bacterial and archaeal community composition between both zones, revealing temporal niche adaptation with flooding treatment. Strongest alterations were found in Drained, likely due to inundation-mediated changes in C-binding capacities.
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Affiliation(s)
- Thomas Dinter
- Soil Science of Temperate Ecosystems, Büsgenweg 2, 37077 Göttingen, University of Göttingen, Germany
| | - Simone Geihser
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Grisebachstraße 8, 37077 Göttingen, University of Göttingen, Germany
| | - Matthias Gube
- Soil Science of Temperate Ecosystems, Büsgenweg 2, 37077 Göttingen, University of Göttingen, Germany
| | - Rolf Daniel
- Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Grisebachstraße 8, 37077 Göttingen, University of Göttingen, Germany
| | - Yakov Kuzyakov
- Soil Science of Temperate Ecosystems, Büsgenweg 2, 37077 Göttingen, University of Göttingen, Germany
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19
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Arnaud M, Baird AJ, Morris PJ, Dang TH, Nguyen TT. Sensitivity of mangrove soil organic matter decay to warming and sea level change. GLOBAL CHANGE BIOLOGY 2020; 26:1899-1907. [PMID: 31750606 DOI: 10.1111/gcb.14931] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/20/2019] [Indexed: 06/10/2023]
Abstract
Mangroves are among the world's most carbon-dense ecosystems, but they are threatened by rapid climate change and rising sea levels. The accumulation and decomposition of soil organic matter (SOM) are closely tied to mangroves' carbon sink functions and resistance to rising sea levels. However, few studies have investigated the response of mangrove SOM dynamics to likely future environmental conditions. We quantified how mangrove SOM decay is affected by predicted global warming (+4°C), sea level changes (simulated by altering of the inundation duration to 0, 2, and 6 hr/day), and their interaction. Whilst changes in inundation duration between 2 and 6 hr/day did not affect SOM decay, the treatment without inundation led to a 60% increase. A warming of 4°C caused SOM decay to increase by 21%, but longer inundation moderated this temperature-driven increase. Our results indicate that (a) sea level rise is unlikely to decrease the SOM decay rate, suggesting that previous mangrove elevation gain, which has allowed mangroves to persist in areas of sea level rise, might result from changes in root production and/or mineral sedimentation; (b) sea level fall events, predicted to double in frequency and area, will cause periods of intensified SOM decay; (c) changing tidal regimes in mangroves due to sea level rise might attenuate increases in SOM decay caused by global warming. Our results have important implications for forecasting mangrove carbon dynamics and the persistence of mangroves and other coastal wetlands under future scenarios of climate change.
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Affiliation(s)
- Marie Arnaud
- School of Geography, University of Leeds, Leeds, UK
| | - Andy J Baird
- School of Geography, University of Leeds, Leeds, UK
| | | | - Thuong Huyen Dang
- Faculty of Geology and Petroleum Engineering, Ho Chí Minh City University of Technology (HCMUT), Ho Chí Minh, Vietnam
| | - Tai Tue Nguyen
- Faculty of Geology, VNU University of Science, Vietnam National University, Hanoi, Ha Noi, Vietnam
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20
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Kim J, Chaudhary DR, Lee J, Byun C, Ding W, Kwon BO, Khim JS, Kang H. Microbial mechanism for enhanced methane emission in deep soil layer of Phragmites-introduced tidal marsh. ENVIRONMENT INTERNATIONAL 2020; 134:105251. [PMID: 31711014 DOI: 10.1016/j.envint.2019.105251] [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: 06/24/2019] [Revised: 09/10/2019] [Accepted: 10/07/2019] [Indexed: 06/10/2023]
Abstract
The introduction of Phragmites australis is known to substantially increase methane emission in the tidal salt marsh. Previous studies suggested that enhanced carbon input by the introduction may stimulate methanogenic activity. However, the exact mechanisms and the effects of the introduction of P. australis to methane dynamics in the deep soil layer are still unclear. In this study we collected 1 m deep intact soil cores and gas samples at native Suaeda japonica- and P. australis-vegetated temperate tidal salt marshes in Suncheon Bay, Republic of Korea. Rates of methane emission and vertical distribution of soil biogeochemistry and microbial communities were analyzed to understand the relationship among chemical and microbiological properties. The introduction of P. australis significantly enhanced methane emission in sites, which was caused by increased DOC and reduced competitive inhibition between sulfate reducer and methanogens. In particular, reduced competitive inhibition between sulfate reducers and methanogens in deep soil layer may play a substantial role in the enhanced methane emission by the introduction of P. australis. Potential methane production was also significantly higher in deeper soil layers than the surface soil layer. We suggest that deep soil layer plays a critical role in the methane dynamics of tidal salt marsh which is introduced by deep root plants, such as P. australis.
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Affiliation(s)
- Jinhyun Kim
- School of Civil and Environmental Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Doongar R Chaudhary
- Marine Biotechnology and Ecology Division, Central Salt and Marine Chemicals Research Institute (CSIR), Bhavnagar, Gujarat 364 002, India
| | - Jaehyun Lee
- School of Civil and Environmental Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Chaeho Byun
- School of Civil and Environmental Engineering, Yonsei University, Seoul 03722, Republic of Korea
| | - Weixin Ding
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
| | - Bong-Oh Kwon
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea
| | - Jong Seong Khim
- School of Earth and Environmental Sciences & Research Institute of Oceanography, Seoul National University, Seoul 08826, Republic of Korea
| | - Hojeong Kang
- School of Civil and Environmental Engineering, Yonsei University, Seoul 03722, Republic of Korea.
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21
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Mueller P, Granse D, Nolte S, Weingartner M, Hoth S, Jensen K. Unrecognized controls on microbial functioning in Blue Carbon ecosystems: The role of mineral enzyme stabilization and allochthonous substrate supply. Ecol Evol 2020; 10:998-1011. [PMID: 32015860 PMCID: PMC6988540 DOI: 10.1002/ece3.5962] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 11/11/2019] [Accepted: 12/05/2019] [Indexed: 11/05/2022] Open
Abstract
Tidal wetlands are effective carbon sinks, mitigating climate change through the long-term removal of atmospheric CO2. Studies along surface-elevation and thus flooding-frequency gradients in tidal wetlands are often used to understand the effects of accelerated sea-level rise on carbon sequestration, a process that is primarily determined by the balance of primary production and microbial decomposition. It has often been hypothesized that rates of microbial decomposition would increase with elevation and associated increases in soil oxygen availability; however, previous studies yield a wide range of outcomes and equivocal results. Our mechanistic understanding of the elevation-decomposition relationship is limited because most effort has been devoted to understanding the terminal steps of the decomposition process. A few studies assessed microbial exo-enzyme activities (EEAs) as initial and rate-limiting steps that often reveal important insight into microbial energy and nutrient constraints. The present study assessed EEAs and microbial abundance along a coastal ecotone stretching a flooding gradient from tidal flat to high marsh in the European Wadden Sea. We found that stabilization of exo-enzymes to mineral sediments leads to high specific EEAs at low substrate concentrations in frequently flooded, sediment-rich zones of the studied ecotone. We argue that the high background activity of a mineral-associated enzyme pool provides a stable decomposition matrix in highly dynamic, frequently flooded zones. Furthermore, we demonstrate that microbial communities are less nutrient limited in frequently flooded zones, where inputs of nutrient-rich marine organic matter are higher. This was reflected in both increasing exo-enzymatic carbon versus nutrient acquisition and decreasing fungal versus bacterial abundance with increasing flooding frequency. Our findings thereby suggest two previously unrecognized mechanisms that may contribute to stimulated microbial activity despite decreasing oxygen availability in response to accelerated sea-level rise.
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Affiliation(s)
- Peter Mueller
- Institute of Soil ScienceUniversität HamburgHamburgGermany
- Applied Plant EcologyInstitute of Plant Science and MicrobiologyUniversität HamburgHamburgGermany
| | - Dirk Granse
- Applied Plant EcologyInstitute of Plant Science and MicrobiologyUniversität HamburgHamburgGermany
| | - Stefanie Nolte
- School of Environmental SciencesUniversity of East AngliaNorwichUnited Kingdom
- Centre for Environment, Fisheries and Aquaculture ScienceLowestoftUnited Kingdom
| | - Magdalena Weingartner
- Molecular Plant Physiology, Institute of Plant Science and MicrobiologyUniversität HamburgHamburgGermany
| | - Stefan Hoth
- Molecular Plant Physiology, Institute of Plant Science and MicrobiologyUniversität HamburgHamburgGermany
| | - Kai Jensen
- Applied Plant EcologyInstitute of Plant Science and MicrobiologyUniversität HamburgHamburgGermany
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22
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Haynes KM, Kane ES, Potvin L, Lilleskov EA, Kolka RK, Mitchell CPJ. Impacts of experimental alteration of water table regime and vascular plant community composition on peat mercury profiles and methylmercury production. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 682:611-622. [PMID: 31129544 DOI: 10.1016/j.scitotenv.2019.05.072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/22/2019] [Accepted: 05/06/2019] [Indexed: 06/09/2023]
Abstract
Climate change is expected to alter the hydrology and vascular plant communities in peatland ecosystems. These changes may have as yet unexplored impacts on peat mercury (Hg) concentrations and net methylmercury (MeHg) production. In this study, peat was collected from PEATcosm, an outdoor, controlled mesocosm experiment where peatland water table regimes and vascular plant functional groups were manipulated over several years to simulate potential climate change effects. Potential Hg(II) methylation and MeHg demethylation rate constants were assessed using enriched stable isotope incubations at the end of the study in 2015, and ambient peat total Hg (THg) and MeHg concentration depth profiles were tracked annually from 2011 to 2014. Peat THg and MeHg concentrations and the proportion of THg methylated (%MeHg) increased significantly within the zone of water table fluctuation when water tables were lowered, but potential Hg(II) methylation rate constants were similar regardless of water table treatment. When sedges dominate over ericaceous shrubs, MeHg concentrations and %MeHg became significantly elevated within the sedge rooting zone. Increased desorption of Hg(II) and MeHg from the solid phase peat into pore water occurred with a lowered water table and predominant sedge cover, likely due to greater aerobic peat decomposition. Deeper, more variable water tables and a transition to sedge-dominated communities coincided with increased MeHg accumulation within the zone of water table fluctuation. Sustained high water tables promoted the net downward migration of Hg(II) and MeHg. The simultaneous decrease in Hg(II) and MeHg concentrations in the near-surface peat and accumulation deeper in the peat profile, combined with the trends in Hg(II) and MeHg partitioning to mobile pore waters, suggest that changes to peatland hydrology and vascular plant functional groups redistribute peat Hg(II) and MeHg via vertical hydrochemical transport mechanisms.
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Affiliation(s)
- Kristine M Haynes
- University of Toronto Scarborough, Department of Physical and Environmental Sciences, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada; University of Toronto, Department of Geography, 100 St. George Street, Toronto, Ontario M5S 3G3, Canada.
| | - Evan S Kane
- Michigan Technological University, School of Forest Resources and Environmental Science, Houghton, MI 49931, USA; USDA Forest Service Northern Research Station, Houghton, MI 49931, USA
| | - Lynette Potvin
- USDA Forest Service Northern Research Station, Houghton, MI 49931, USA
| | - Erik A Lilleskov
- USDA Forest Service Northern Research Station, Houghton, MI 49931, USA
| | - Randall K Kolka
- USDA Forest Service Northern Research Station, Grand Rapids, MN 55744, USA
| | - Carl P J Mitchell
- University of Toronto Scarborough, Department of Physical and Environmental Sciences, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada; University of Toronto, Department of Geography, 100 St. George Street, Toronto, Ontario M5S 3G3, Canada
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23
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Chen Y, Cao J, Zhao J, Wu J, Zou X, Fu S, Zhang W. Labile C dynamics reflect soil organic carbon sequestration capacity: Understory plants drive topsoil C process in subtropical forests. Ecosphere 2019. [DOI: 10.1002/ecs2.2784] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Yuanqi Chen
- Hunan Province Key Laboratory of Coal Resources Clean‐utilization and Mine Environment Protection Hunan University of Science and Technology Xiangtan 411201 China
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 China
| | - Jianbo Cao
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 China
- University of Chinese Academy of Sciences Beijing 100049 China
| | - Jie Zhao
- Key Laboratory of Agro‐Ecological Processes in Subtropical Region Institute of Subtropical Agriculture Chinese Academy of Sciences Changsha 410125 China
| | - Jianping Wu
- School of Ecology and Environmental Science Yunnan University Kunming 650091 China
| | - Xiaoming Zou
- Department of Environmental Sciences University of Puerto Rico P.O. Box 70377 San Juan Puerto Rico 00936‐8377 USA
| | - Shenglei Fu
- Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions Ministry of Education College of Environment and Planning Henan University Kaifeng 475004 China
| | - Weixin Zhang
- Key Laboratory of Geospatial Technology for the Middle and Lower Yellow River Regions Ministry of Education College of Environment and Planning Henan University Kaifeng 475004 China
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24
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Mueller P, Ladiges N, Jack A, Schmiedl G, Kutzbach L, Jensen K, Nolte S. Assessing the long‐term carbon‐sequestration potential of the semi‐natural salt marshes in the European Wadden Sea. Ecosphere 2019. [DOI: 10.1002/ecs2.2556] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Peter Mueller
- Plant Ecology Institute of Plant Science and Microbiology Universität Hamburg Ohnhorststr. 18 22609 Hamburg Germany
| | - Nils Ladiges
- Center for Earth System Research and Sustainability Institute of Soil Science Universität Hamburg Allende‐Platz 2 20146 Hamburg Germany
| | - Alexander Jack
- Center for Earth System Research and Sustainability Institute of Soil Science Universität Hamburg Allende‐Platz 2 20146 Hamburg Germany
| | - Gerhard Schmiedl
- Center for Earth System Research and Sustainability Institute for Geology Universität Hamburg Bundesstr. 55 20146 Hamburg Germany
| | - Lars Kutzbach
- Center for Earth System Research and Sustainability Institute of Soil Science Universität Hamburg Allende‐Platz 2 20146 Hamburg Germany
| | - Kai Jensen
- Plant Ecology Institute of Plant Science and Microbiology Universität Hamburg Ohnhorststr. 18 22609 Hamburg Germany
| | - Stefanie Nolte
- Plant Ecology Institute of Plant Science and Microbiology Universität Hamburg Ohnhorststr. 18 22609 Hamburg Germany
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25
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Helton AM, Ardón M, Bernhardt ES. Hydrologic Context Alters Greenhouse Gas Feedbacks of Coastal Wetland Salinization. Ecosystems 2019. [DOI: 10.1007/s10021-018-0325-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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26
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Doughty CL, Cavanaugh KC, Ambrose RF, Stein ED. Evaluating regional resiliency of coastal wetlands to sea level rise through hypsometry-based modeling. GLOBAL CHANGE BIOLOGY 2019; 25:78-92. [PMID: 30378214 DOI: 10.1111/gcb.14429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 07/24/2018] [Indexed: 06/08/2023]
Abstract
Sea level rise (SLR) threatens coastal wetlands worldwide, yet the fate of individual wetlands will vary based on local topography, wetland morphology, sediment dynamics, hydrologic processes, and plant-mediated feedbacks. Local variability in these factors makes it difficult to predict SLR effects across wetlands or to develop a holistic regional perspective on SLR response for a diversity of wetland types. To improve regional predictions of SLR impacts to coastal wetlands, we developed a model that addresses the scale-dependent factors controlling SLR response and accommodates different levels of data availability. The model quantifies SLR-driven habitat conversion within wetlands across a region by predicting changes in individual wetland hypsometry. This standardized approach can be applied to all wetlands in a region regardless of data availability, making it ideal for modeling SLR response across a range of scales. Our model was applied to 105 wetlands in southern California that spanned a broad range of typology and data availability. Our findings suggest that if wetlands are confined to their current extents, the region will lose 12% of marsh habitats (vegetated marsh and unvegetated flats) with 0.6 m of SLR (projected for 2050) and 48% with 1.7 m of SLR (projected for 2100). Habitat conversion was more drastic in wetlands with larger proportions of marsh habitats relative to subtidal habitats and occurred more rapidly in small lagoons relative to larger sites. Our assessment can inform management of coastal wetland vulnerability, improve understanding of the SLR drivers relevant to individual wetlands, and highlight significant data gaps that impede SLR response modeling across spatial scales. This approach augments regional SLR assessments by considering spatial variability in SLR response drivers, addressing data gaps, and accommodating wetland diversity, which will provide greater insights into regional SLR response that are relevant to coastal management and restoration efforts.
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Affiliation(s)
- Cheryl L Doughty
- Department of Geography, University of California, Los Angeles, California
| | - Kyle C Cavanaugh
- Department of Geography, University of California, Los Angeles, California
| | - Richard F Ambrose
- Department of Environmental Health Sciences, Institute of the Environment and Sustainability, University of California, Los Angeles, California
| | - Eric D Stein
- Biology Department, Southern California Coastal Water Research Project, Costa Mesa, California
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27
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Koop-Jakobsen K, Mueller P, Meier RJ, Liebsch G, Jensen K. Plant-Sediment Interactions in Salt Marshes - An Optode Imaging Study of O 2, pH, and CO 2 Gradients in the Rhizosphere. FRONTIERS IN PLANT SCIENCE 2018; 9:541. [PMID: 29774037 PMCID: PMC5943611 DOI: 10.3389/fpls.2018.00541] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 04/06/2018] [Indexed: 05/26/2023]
Abstract
In many wetland plants, belowground transport of O2 via aerenchyma tissue and subsequent O2 loss across root surfaces generates small oxic root zones at depth in the rhizosphere with important consequences for carbon and nutrient cycling. This study demonstrates how roots of the intertidal salt-marsh plant Spartina anglica affect not only O2, but also pH and CO2 dynamics, resulting in distinct gradients of O2, pH, and CO2 in the rhizosphere. A novel planar optode system (VisiSens TD®, PreSens GmbH) was used for taking high-resolution 2D-images of the O2, pH, and CO2 distribution around roots during alternating light-dark cycles. Belowground sediment oxygenation was detected in the immediate vicinity of the roots, resulting in oxic root zones with a 1.7 mm radius from the root surface. CO2 accumulated around the roots, reaching a concentration up to threefold higher than the background concentration, and generally affected a larger area within a radius of 12.6 mm from the root surface. This contributed to a lowering of pH by 0.6 units around the roots. The O2, pH, and CO2 distribution was recorded on the same individual roots over diurnal light cycles in order to investigate the interlinkage between sediment oxygenation and CO2 and pH patterns. In the rhizosphere, oxic root zones showed higher oxygen concentrations during illumination of the aboveground biomass. In darkness, intraspecific differences were observed, where some plants maintained oxic root zones in darkness, while others did not. However, the temporal variation in sediment oxygenation was not reflected in the temporal variations of pH and CO2 around the roots, which were unaffected by changing light conditions at all times. This demonstrates that plant-mediated sediment oxygenation fueling microbial decomposition and chemical oxidation has limited impact on the dynamics of pH and CO2 in S. anglica rhizospheres, which may in turn be controlled by other processes such as root respiration and root exudation.
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Affiliation(s)
- Ketil Koop-Jakobsen
- MARUM – Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Peter Mueller
- Applied Plant Ecology, Biocenter Klein Flottbek, University of Hamburg, Hamburg, Germany
| | | | | | - Kai Jensen
- Applied Plant Ecology, Biocenter Klein Flottbek, University of Hamburg, Hamburg, Germany
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Lenzewski N, Mueller P, Meier RJ, Liebsch G, Jensen K, Koop-Jakobsen K. Dynamics of oxygen and carbon dioxide in rhizospheres of Lobelia dortmanna - a planar optode study of belowground gas exchange between plants and sediment. THE NEW PHYTOLOGIST 2018; 218:131-141. [PMID: 29314005 DOI: 10.1111/nph.14973] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/21/2017] [Indexed: 05/24/2023]
Abstract
Root-mediated CO2 uptake, O2 release and their effects on O2 and CO2 dynamics in the rhizosphere of Lobelia dortmanna were investigated. Novel planar optode technology, imaging CO2 and O2 distribution around single roots, provided insights into the spatiotemporal patterns of gas exchange between roots, sediment and microbial community. In light, O2 release and CO2 uptake were pronounced, resulting in a distinct oxygenated zone (radius: c. 3 mm) and a CO2 -depleted zone (radius: c. 2 mm) around roots. Simultaneously, however, microbial CO2 production was stimulated within a larger zone around the roots (radius: c. 10 mm). This gave rise to a distinct pattern with a CO2 minimum at the root surface and a CO2 maximum c. 2 mm away from the root. In darkness, CO2 uptake ceased, and the CO2 -depleted zone disappeared within 2 h. By contrast, the oxygenated root zone remained even after 8 h, but diminished markedly over time. A tight coupling between photosynthetic processes and the spatiotemporal dynamics of O2 and CO2 in the rhizosphere of Lobelia was demonstrated, and we suggest that O2 -induced stimulation of the microbial community in the sediment increases the supply of inorganic carbon for photosynthesis by building up a CO2 reservoir in the rhizosphere.
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Affiliation(s)
- Nikola Lenzewski
- Applied Plant Ecology, Biocenter Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany
| | - Peter Mueller
- Applied Plant Ecology, Biocenter Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany
| | | | - Gregor Liebsch
- PreSens, Precision Sensing GmbH, Am BioPark 11, 93053, Regensburg, Germany
| | - Kai Jensen
- Applied Plant Ecology, Biocenter Klein Flottbek, Universität Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany
| | - Ketil Koop-Jakobsen
- MARUM - Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse 8, 28359, Bremen, Germany
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Yang Y, Dou Y, Huang Y, An S. Links between Soil Fungal Diversity and Plant and Soil Properties on the Loess Plateau. Front Microbiol 2017; 8:2198. [PMID: 29163460 PMCID: PMC5682006 DOI: 10.3389/fmicb.2017.02198] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 10/26/2017] [Indexed: 01/28/2023] Open
Abstract
Previous studies have revealed inconsistent correlations between fungal diversity and plant/soil properties from local to global scales. Here, we investigated the internal relationships between soil fungal diversity and plant/soil properties on the Loess Plateau following vegetation restoration, using Illumina sequencing of the internal transcribed spacer 2 (ITS2) region for fungal identification. We found significant effects of land use types (Af, Artificial forest; Ns, Natural shrub; Ag, Artificial grassland; Ng, Natural grassland; Sc, slope cropland) on soil fungal communities composition, and the dominant phyla were Ascomycota, Basidiomycota, and Zygomycota, which transitioned from Basidiomycota-dominant to Ascomycota-dominant community due to vegetation restoration. The Chao1 richness, Shannon's diversity and ACE indices were significantly influenced by land use types with the order of Ns > Af > Ng > Ag > Sc, and the total number of OTUs varied widely. In contrast, Good's coverage and Simpson's diversity indicated no significant difference among land use types (p > 0.05). Correlation analysis showed that plant and soil properties were closely related to fungal diversity regardless of land use types. In addition, soil organic carbon (SOC) and Hplant (plant richness, Shannon-Wiener index) were strong driving factors that explained fungal diversity. As revealed by the structural equation model (SEM) and generalized additive models (GAMs), fungal diversity was directly and indirectly affected by soil and plant properties, respectively, providing evidence for strong links between soil fungal diversity and plant and soil properties on the Loess Plateau.
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Affiliation(s)
- Yang Yang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, China
| | - Yanxing Dou
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, China
| | - Yimei Huang
- College of Natural Resources and Environment, Northwest A&F University, Yangling, China
| | - Shaoshan An
- College of Natural Resources and Environment, Northwest A&F University, Yangling, China
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, China
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Mueller P, Granse D, Nolte S, Do HT, Weingartner M, Hoth S, Jensen K. Top-down control of carbon sequestration: grazing affects microbial structure and function in salt marsh soils. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:1435-1450. [PMID: 28317257 DOI: 10.1002/eap.1534] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 12/09/2016] [Accepted: 02/07/2017] [Indexed: 05/28/2023]
Abstract
Tidal wetlands have been increasingly recognized as long-term carbon sinks in recent years. Work on carbon sequestration and decomposition processes in tidal wetlands focused so far mainly on effects of global-change factors such as sea-level rise and increasing temperatures. However, little is known about effects of land use, such as livestock grazing, on organic matter decomposition and ultimately carbon sequestration. The present work aims at understanding the mechanisms by which large herbivores can affect organic matter decomposition in tidal wetlands. This was achieved by studying both direct animal-microbe interactions and indirect animal-plant-microbe interactions in grazed and ungrazed areas of two long-term experimental field sites at the German North Sea coast. We assessed bacterial and fungal gene abundance using quantitative PCR, as well as the activity of microbial exo-enzymes by conducting fluorometric assays. We demonstrate that grazing can have a profound impact on the microbial community structure of tidal wetland soils, by consistently increasing the fungi-to-bacteria ratio by 38-42%, and therefore potentially exerts important control over carbon turnover and sequestration. The observed shift in the microbial community was primarily driven by organic matter source, with higher contributions of recalcitrant autochthonous (terrestrial) vs. easily degradable allochthonous (marine) sources in grazed areas favoring relative fungal abundance. We propose a novel and indirect form of animal-plant-microbe interaction: top-down control of aboveground vegetation structure determines the capacity of allochthonous organic matter trapping during flooding and thus the structure of the microbial community. Furthermore, our data provide the first evidence that grazing slows down microbial exo-enzyme activity and thus decomposition through changes in soil redox chemistry. Activities of enzymes involved in C cycling were reduced by 28-40%, while activities of enzymes involved in N cycling were not consistently affected by grazing. It remains unclear if this is a trampling-driven direct grazing effect, as hypothesized in earlier studies, or if the effect on redox chemistry is plant mediated and thus indirect. This study improves our process-level understanding of how grazing can affect the microbial ecology and biogeochemistry of semi-terrestrial ecosystems that may help explain and predict differences in C turnover and sequestration rates between grazed and ungrazed systems.
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Affiliation(s)
- Peter Mueller
- Applied Plant Ecology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststraße 18, 22609, Hamburg, Germany
| | - Dirk Granse
- Applied Plant Ecology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststraße 18, 22609, Hamburg, Germany
| | - Stefanie Nolte
- Applied Plant Ecology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststraße 18, 22609, Hamburg, Germany
| | - Hai Thi Do
- Applied Plant Ecology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststraße 18, 22609, Hamburg, Germany
| | - Magdalena Weingartner
- Molecular Plant Physiology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststraße 18, 22609, Hamburg, Germany
| | - Stefan Hoth
- Molecular Plant Physiology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststraße 18, 22609, Hamburg, Germany
| | - Kai Jensen
- Applied Plant Ecology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststraße 18, 22609, Hamburg, Germany
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Bernal B, Megonigal JP, Mozdzer TJ. An invasive wetland grass primes deep soil carbon pools. GLOBAL CHANGE BIOLOGY 2017; 23:2104-2116. [PMID: 27779794 DOI: 10.1111/gcb.13539] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 09/21/2016] [Indexed: 05/25/2023]
Abstract
Understanding the processes that control deep soil carbon (C) dynamics and accumulation is of key importance, given the relevance of soil organic matter (SOM) as a vast C pool and climate change buffer. Methodological constraints of measuring SOM decomposition in the field prevent the addressing of real-time rhizosphere effects that regulate nutrient cycling and SOM decomposition. An invasive lineage of Phragmites australis roots deeper than native vegetation (Schoenoplectus americanus and Spartina patens) in coastal marshes of North America and has potential to dramatically alter C cycling and accumulation in these ecosystems. To evaluate the effect of deep rooting on SOM decomposition we designed a mesocosm experiment that differentiates between plant-derived, surface SOM-derived (0-40 cm, active root zone of native marsh vegetation), and deep SOM-derived mineralization (40-80 cm, below active root zone of native vegetation). We found invasive P. australis allocated the highest proportion of roots in deeper soils, differing significantly from the native vegetation in root : shoot ratio and belowground biomass allocation. About half of the CO2 produced came from plant tissue mineralization in invasive and native communities; the rest of the CO2 was produced from SOM mineralization (priming). Under P. australis, 35% of the CO2 was produced from deep SOM priming and 9% from surface SOM. In the native community, 9% was produced from deep SOM priming and 44% from surface SOM. SOM priming in the native community was proportional to belowground biomass, while P. australis showed much higher priming with less belowground biomass. If P. australis deep rooting favors the decomposition of deep-buried SOM accumulated under native vegetation, P. australis invasion into a wetland could fundamentally change SOM dynamics and lead to the loss of the C pool that was previously sequestered at depth under the native vegetation, thereby altering the function of a wetland as a long-term C sink.
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Affiliation(s)
- Blanca Bernal
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD, 21037, USA
| | - J Patrick Megonigal
- Smithsonian Environmental Research Center, 647 Contees Wharf Rd, Edgewater, MD, 21037, USA
| | - Thomas J Mozdzer
- Department of Biology, Bryn Mawr College, 101 N Merion Ave, Bryn Mawr, PA, 19010, USA
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Janousek CN, Buffington KJ, Guntenspergen GR, Thorne KM, Dugger BD, Takekawa JY. Inundation, Vegetation, and Sediment Effects on Litter Decomposition in Pacific Coast Tidal Marshes. Ecosystems 2017. [DOI: 10.1007/s10021-017-0111-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Mozdzer TJ, Langley JA, Mueller P, Megonigal JP. Erratum to: Deep rooting and global change facilitate spread of invasive grass. Biol Invasions 2016. [DOI: 10.1007/s10530-016-1242-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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