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Kubota M, Matsushita N, Nakamura T, Fukuda K. Nitrogen fixation and nifH gene diversity in cyanobacteria living on feather mosses in a subalpine forest of Mt. Fuji. Oecologia 2023; 201:749-760. [PMID: 36808304 PMCID: PMC10038973 DOI: 10.1007/s00442-023-05334-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 02/07/2023] [Indexed: 02/23/2023]
Abstract
In the boreal forests, feather mosses such as Hylocomium splendens and Pleurozium schreberi are colonized by cyanobacteria, which provide large amounts of nitrogen to forest ecosystems through nitrogen fixation. Although these feather mosses are also ubiquitous in subalpine forests of East Asia, little is known regarding their associated cyanobacteria and their ability to fix nitrogen. In this study, we investigated (1) whether cyanobacteria co-exist and fix nitrogen in the two species of feather mosses that cover the ground surface in a subalpine forest of Mt. Fuji, (2) whether cyanobacteria belonging to a common cluster with boreal forests are found in feather mosses in Mt. Fuji, and (3) whether moss-associated nitrogen fixation rates differed among moss growing substrates, canopy openness, and moss nitrogen concentrations in the same forest area. Our results showed that cyanobacteria colonized feather mosses in the subalpine forests of Mt. Fuji and acetylene reduction rates as an index of nitrogen fixation tended to be higher in H. splendens than in P. schreberi. Based on analysis of the nifH gene, 43 bacterial operational taxonomic units (OTUs) were identified, 28 of which represented cyanobacteria. Among the five clusters of cyanobacteria classified based on their nifH gene and identified in northern Europe, four (Nostoc cluster I, Nostoc cluster II, Stigonema cluster, and nifH2 cluster) were also found at Mt. Fuji. The acetylene reduction rate differed depending on the moss growing substrate and the total nitrogen concentration of moss shoots, and a strong negative correlation was observed with the total nitrogen concentration.
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Affiliation(s)
- Masayuki Kubota
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-Ku, Tokyo, Japan.
| | - Norihisa Matsushita
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-Ku, Tokyo, Japan
| | - Toshihiko Nakamura
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-Ku, Tokyo, Japan
| | - Kenji Fukuda
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-Ku, Tokyo, Japan
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2
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Niu S, Song L, Wang J, Luo Y, Yu G. Dynamic carbon-nitrogen coupling under global change. Sci China Life Sci 2023. [PMID: 36680674 DOI: 10.1007/s11427-022-2245-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/21/2022] [Indexed: 01/22/2023]
Abstract
Carbon-nitrogen coupling is a fundamental principle in ecosystem ecology. However, how the coupling responds to global change has not yet been examined. Through a comprehensive and systematic literature review, we assessed how the dynamics of carbon processes change with increasing nitrogen input and how nitrogen processes change with increasing carbon input under global change. Our review shows that nitrogen input to the ecosystem mostly stimulates plant primary productivity but inconsistently decreases microbial activities or increases soil carbon sequestration, with nitrogen leaching and nitrogenous gas emission rapidly increasing. Nitrogen fixation increases and nitrogen leaching decreases to improve soil nitrogen availability and support plant growth and ecosystem carbon sequestration under elevated CO2 and temperature or along ecosystem succession. We conclude that soil nitrogen cycle processes continually adjust to change in response to either overload under nitrogen addition or deficiency under CO2 enrichment and ecosystem succession to couple with carbon cycling. Indeed, processes of both carbon and nitrogen cycles continually adjust under global change, leading to dynamic coupling in carbon and nitrogen cycles. The dynamic coupling framework reconciles previous debates on the "uncoupling" or "decoupling" of ecosystem carbon and nitrogen cycles under global change. Ecosystem models failing to simulate these dynamic adjustments cannot simulate carbon-nitrogen coupling nor predict ecosystem carbon sequestration well.
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Cleveland CC, Reis CRG, Perakis SS, Dynarski KA, Batterman SA, Crews TE, Gei M, Gundale MJ, Menge DNL, Peoples MB, Reed SC, Salmon VG, Soper FM, Taylor BN, Turner MG, Wurzburger N. Exploring the Role of Cryptic Nitrogen Fixers in Terrestrial Ecosystems: A Frontier in Nitrogen Cycling Research. Ecosystems 2022. [DOI: 10.1007/s10021-022-00804-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Permin A, Horwath AB, Metcalfe DB, Priemé A, Rousk K. ‘High nitrogen‐fixing rates associated with ground‐covering mosses in a tropical mountain cloud forest will decrease drastically in a future climate’. Funct Ecol 2022. [DOI: 10.1111/1365-2435.14088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Aya Permin
- Terrestrial Ecology Section, Department of Biology University of Copenhagen Copenhagen Denmark
- Center for Permafrost (CENPERM) University of Copenhagen Copenhagen Denmark
| | - Aline B. Horwath
- Biological and Environmental Sciences, Faculty of Natural Sciences University of Stirling Stirling UK
| | - Daniel B. Metcalfe
- Department of Physical Geography and Ecosystem Science Lund University SE Lund Sweden
- Department of Ecology and Environmental Science SE Umeå Sweden
| | - Anders Priemé
- Center for Permafrost (CENPERM) University of Copenhagen Copenhagen Denmark
- Section of Microbiology, Department of Biology University of Copenhagen Copenhagen Denmark
| | - Kathrin Rousk
- Terrestrial Ecology Section, Department of Biology University of Copenhagen Copenhagen Denmark
- Center for Permafrost (CENPERM) University of Copenhagen Copenhagen Denmark
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Rodríguez-Rodríguez JC, Bergeron Y, Kembel SW, Fenton NJ. Dominance of coniferous and broadleaved trees drives bacterial associations with boreal feather mosses. Environ Microbiol 2022; 24:3517-3528. [PMID: 35416394 DOI: 10.1111/1462-2920.16013] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 04/09/2022] [Accepted: 04/09/2022] [Indexed: 12/01/2022]
Abstract
The composition of ecologically important moss-associated bacterial communities seems to be mainly driven by host species but may also be shaped by environmental conditions related with tree dominance. The moss phyllosphere has been studied in coniferous forests while broadleaf forests remain understudied. To determine if host species or environmental conditions defined by tree dominance drives the bacterial diversity in the moss phyllosphere, we used 16S rRNA gene amplicon sequencing to quantify changes in bacterial communities as a function of host species (Pleurozium schreberi and Ptilium crista-castrensis) and forest type (coniferous black spruce versus deciduous broadleaf trembling aspen) in eastern Canada. The overall composition of moss phyllosphere was defined by the interaction of both factors, though most of bacterial phyla were determined by a strong effect of forest type. Bacterial α-diversity was highest in spruce forests, while there was greater turnover (β-diversity) and higher γ-diversity in aspen forests. Unexpectedly, Cyanobacteria were much more relatively abundant in aspen than in spruce forests, with the cyanobacteria family Nostocaceae differing the most between forest types. Our results advance the understanding of moss-associated microbial communities among coniferous and broadleaf deciduous forests, which are important with the increasing changes in tree dominance in the boreal system. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Juanita C Rodríguez-Rodríguez
- Forest Research Institute (IRF) , Université du Québec en Abitibi-Témiscamingue (UQAT), Rouyn-Noranda, QC J9X 5E4, Canada. 2 Département des sciences biologiques, Université du Québec à Montréal (UQAM), Montréal, QC, H2L 2C4, Canada
| | - Yves Bergeron
- Forest Research Institute (IRF) , Université du Québec en Abitibi-Témiscamingue (UQAT), Rouyn-Noranda, QC J9X 5E4, Canada. 2 Département des sciences biologiques, Université du Québec à Montréal (UQAM), Montréal, QC, H2L 2C4, Canada
| | | | - Nicole J Fenton
- Forest Research Institute (IRF) , Université du Québec en Abitibi-Témiscamingue (UQAT), Rouyn-Noranda, QC J9X 5E4, Canada. 2 Département des sciences biologiques, Université du Québec à Montréal (UQAM), Montréal, QC, H2L 2C4, Canada
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Törmänen T, Smolander A. Biological nitrogen fixation in logging residue piles of different tree species after final felling. J Environ Manage 2022; 303:113942. [PMID: 34810023 DOI: 10.1016/j.jenvman.2021.113942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 09/07/2021] [Accepted: 10/11/2021] [Indexed: 06/13/2023]
Abstract
Logging residues influence the nitrogen cycling processes that play a key role in risks for nitrogen losses from the ecosystem after the clear cut. Therefore, our aim was to identify the potential ability of logging residues to gain external nitrogen via biological nitrogen fixation. We measured biological nitrogen fixation as nitrogenase activity in logging residues of three different tree species (Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and silver birch (Betula pendula Roth.). The study site was located in south-eastern Finland and was clear cut in 2014 and piles of logging residues were established. Sampling was performed in June 2016, September 2018, and August 2019 and nitrogenase activity in branches and needles or leaves was measured using the acetylene (C2H2) reduction assay. Nitrogenase activity (ethylene production) was shown in all residue types. Nitrogenase activity tended to be higher in branches than in needles or leaves and in coniferous residues than in birch. C-to-N ratios were higher in branches than in needles/leaves and in coniferous residues than in birch. Our results indicate that logging residues can acquire external nitrogen from the atmosphere via biological nitrogen fixation and can thus bring nitrogen to the forest ecosystem and substitute some part of the N losses occurring when residues are retained at the site after clear cutting.
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Affiliation(s)
- Tiina Törmänen
- Natural Resources Institute Finland, Latokartanonkaari 9, FI-00790, Helsinki, Finland.
| | - Aino Smolander
- Natural Resources Institute Finland, Latokartanonkaari 9, FI-00790, Helsinki, Finland
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Alvarenga DO, Rousk K. Indirect effects of climate change inhibit N 2 fixation associated with the feathermoss Hylocomium splendens in subarctic tundra. Sci Total Environ 2021; 795:148676. [PMID: 34247067 DOI: 10.1016/j.scitotenv.2021.148676] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 06/15/2021] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Mosses can be responsible for up to 100% of net primary production in arctic and subarctic tundra, and their associations with diazotrophic cyanobacteria have an important role in increasing nitrogen (N) availability in these pristine ecosystems. Predictions about the consequences of climate change in subarctic environments point to increased N mineralization in soil and higher litter deposition due to warming. It is not clear yet how these indirect climate change effects impact moss-cyanobacteria associations and N2 fixation. This work aimed to evaluate the effects of increased N and litter input on biological N2 fixation rates associated with the feathermoss Hylocomium splendens from a tundra heath. H. splendens samples were collected near Abisko, northern Sweden, from a field experiment with annual additions of ammonium chloride and dried birch litter and the combination of both for three years. Samples were analyzed for N2 fixation, cyanobacterial colonization, C and N content and pH. Despite the high N additions, no significant differences in moss N content were found. However, differences between treatments were observed in N2 fixation rates, cyanobacterial colonization and pH, with the combined ammonium+litter treatment causing a significant reduction in the number of branch-colonizing cyanobacteria and N2 fixation, and ammonium additions significantly lowering moss pH. A significant, positive relationship was found between N2 fixation rates, moss colonization by cyanobacteria and pH levels, showing a clear drop in N2 fixation rates at lower pH levels even if larger cyanobacterial populations were present. These results suggest that increased N availability and litter deposition resulting from climate change not only interferes with N2 fixation directly, but also acidifies moss microhabitats and reduces the abundance of associated cyanobacteria, which could eventually impact the N cycle in the Subarctic.
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Affiliation(s)
- Danillo O Alvarenga
- Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark; Centre for Permafrost, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark.
| | - Kathrin Rousk
- Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark; Centre for Permafrost, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark
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Rousk K, Pedersen P, Priemé A, Michelsen A. Extreme freeze-thaw cycles do not affect moss-associated nitrogen fixation across a temperature gradient, but affect nutrient loss from mosses. Acta Oecologica 2021; 113:103796. [DOI: 10.1016/j.actao.2021.103796] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Stuart JEM, Holland-Moritz H, Jean M, Miller SN, Ponciano JM, McDaniel SF, Mack MC. The relationship of C and N stable isotopes to high-latitude moss-associated N 2 fixation. Oecologia 2021. [PMID: 34319437 DOI: 10.1007/s00442-021-05005-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 07/23/2021] [Indexed: 10/20/2022]
Abstract
Moss-associated N2 fixation by epiphytic microbes is a key biogeochemical process in nutrient-limited high-latitude ecosystems. Abiotic drivers, such as temperature and moisture, and the identity of host mosses are critical sources of variation in N2 fixation rates. An understanding of the potential interaction between these factors is essential for predicting N inputs as moss communities change with the climate. To further understand the drivers and results of N2 fixation rate variation, we obtained natural abundance values of C and N isotopes and an associated rate of N2 fixation with 15N2 gas incubations in 34 moss species collected in three regions across Alaska, USA. We hypothesized that δ15N values would increase toward 0‰ with higher N2 fixation to reflect the increasing contribution of fixed N2 in moss biomass. Second, we hypothesized that δ13C and N2 fixation would be positively related, as enriched δ13C signatures reflect abiotic conditions favorable to N2 fixation. We expected that the magnitude of these relationships would vary among types of host mosses, reflecting differences in anatomy and habitat. We found little support for our first hypothesis, with only a modest positive relationship between N2 fixation rates and δ15N in a structural equation model. We found a significant positive relationship between δ13C and N2 fixation only in Hypnales, where the probability of N2 fixation activity reached 95% when δ13C values exceeded - 30.4‰. We conclude that moisture and temperature interact strongly with host moss identity in determining the extent to which abiotic conditions impact associated N2 fixation rates.
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Holland-Moritz H, Stuart JEM, Lewis LR, Miller SN, Mack MC, Ponciano JM, McDaniel SF, Fierer N. The bacterial communities of Alaskan mosses and their contributions to N 2-fixation. Microbiome 2021; 9:53. [PMID: 33622403 PMCID: PMC7903681 DOI: 10.1186/s40168-021-01001-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/08/2021] [Indexed: 05/14/2023]
Abstract
BACKGROUND Mosses in high-latitude ecosystems harbor diverse bacterial taxa, including N2-fixers which are key contributors to nitrogen dynamics in these systems. Yet the relative importance of moss host species, and environmental factors, in structuring these microbial communities and their N2-fixing potential remains unclear. We studied 26 boreal and tundra moss species across 24 sites in Alaska, USA, from 61 to 69° N. We used cultivation-independent approaches to characterize the variation in moss-associated bacterial communities as a function of host species identity and site characteristics. We also measured N2-fixation rates via 15N2 isotopic enrichment and identified potential N2-fixing bacteria using available literature and genomic information. RESULTS Host species identity and host evolutionary history were both highly predictive of moss microbiome composition, highlighting strong phylogenetic coherence in these microbial communities. Although less important, light availability and temperature also influenced composition of the moss microbiome. Finally, we identified putative N2-fixing bacteria specific to some moss hosts, including potential N2-fixing bacteria outside well-studied cyanobacterial clades. CONCLUSIONS The strong effect of host identity on moss-associated bacterial communities demonstrates mosses' utility for understanding plant-microbe interactions in non-leguminous systems. Our work also highlights the likely importance of novel bacterial taxa to N2-fixation in high-latitude ecosystems. Video Abstract.
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Affiliation(s)
- Hannah Holland-Moritz
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO USA
| | - Julia E. M. Stuart
- Center for Ecosystem Science and Society and the Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ USA
| | - Lily R. Lewis
- Provost’s Office, University of Florida, Gainesville, FL USA
| | - Samantha N. Miller
- Center for Ecosystem Science and Society and the Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ USA
| | - Michelle C. Mack
- Center for Ecosystem Science and Society and the Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ USA
| | | | | | - Noah Fierer
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO USA
- Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO USA
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Stuart RK, Pederson ERA, Weyman PD, Weber PK, Rassmussen U, Dupont CL. Bidirectional C and N transfer and a potential role for sulfur in an epiphytic diazotrophic mutualism. ISME J 2020; 14:3068-3078. [PMID: 32814866 PMCID: PMC7784912 DOI: 10.1038/s41396-020-00738-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 06/09/2020] [Accepted: 08/05/2020] [Indexed: 01/23/2023]
Abstract
In nitrogen-limited boreal forests, associations between feathermoss and diazotrophic cyanobacteria control nitrogen inputs and thus carbon cycling, but little is known about the molecular regulators required for initiation and maintenance of these associations. Specifically, a benefit to the cyanobacteria is not known, challenging whether the association is a nutritional mutualism. Targeted mutagenesis of the cyanobacterial alkane sulfonate monooxygenase results in an inability to colonize feathermosses by the cyanobacterium Nostoc punctiforme, suggesting a role for organic sulfur in communication or nutrition. Isotope probing paired with high-resolution imaging mass spectrometry (NanoSIMS) demonstrated bidirectional elemental transfer between partners, with carbon and sulfur both being transferred to the cyanobacteria, and nitrogen transferred to the moss. These results support the hypothesis that moss and cyanobacteria enter a mutualistic exosymbiosis with substantial bidirectional material exchange of carbon and nitrogen and potential signaling through sulfur compounds.
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Affiliation(s)
- Rhona K Stuart
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA.
| | - Eric R A Pederson
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91, Stockholm, Sweden
| | - Philip D Weyman
- J. Craig Venter Institute, La Jolla, CA, 92037, USA
- Zymergen Inc., Emeryville, CA, USA
| | - Peter K Weber
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, 94550, USA
| | - Ulla Rassmussen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91, Stockholm, Sweden
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Zheng M, Zhou Z, Zhao P, Luo Y, Ye Q, Zhang K, Song L, Mo J. Effects of human disturbance activities and environmental change factors on terrestrial nitrogen fixation. Glob Chang Biol 2020; 26:6203-6217. [PMID: 32869422 DOI: 10.1111/gcb.15328] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/21/2020] [Indexed: 06/11/2023]
Abstract
Biological nitrogen (N) fixation plays an important role in terrestrial N cycling and represents a key driver of terrestrial net primary productivity (NPP). Despite the importance of N fixation in terrestrial ecosystems, our knowledge regarding the controls on terrestrial N fixation remains poor. Here, we conducted a meta-analysis (based on 852 observations from 158 studies) of N fixation across three types of ecosystems with different status of disturbance (no management, restoration [previously disturbed], and disturbance [currently disturbed]) and in response to multiple environmental change factors (warming, elevated carbon dioxide [CO2 ], increased precipitation, increased drought, increased N deposition, and their combinations). We explored the mechanisms underlying the changes in N fixation by examining the variations in soil physicochemical properties (bulk density, texture, moisture, and pH), plant and microbial characteristics (dominant plant species numbers, plant coverage, and soil microbial biomass), and soil resources (total carbon, total N, total phosphorus (P), inorganic N, and inorganic P). Human disturbance inhibited non-symbiotic N fixation but not symbiotic N fixation. Terrestrial N fixation was stimulated by warming (+152.7%), elevated CO2 (+19.6%), and increased precipitation (+73.1%) but inhibited by increased drought (-30.4%), N deposition (-31.0%), and combinations of available multiple environmental change factors (-14.5%), the extents of which varied among biomes and ecosystem compartments. Human disturbance reduced the N fixation responses to environmental change factors, which was associated with the changes in soil physicochemical properties (2%-56%, p < .001) and the declines in plant and microbial characteristics (3%-49%, p ≤ .003) and soil resources (6%-48%, p ≤ .03). Overall, our findings reveal for the first time the effects of multiple environmental change factors on terrestrial N fixation and indicate the role of human disturbance activities in inhibiting N fixation, which can improve our understanding, modeling, and prediction of terrestrial N budgets, NPP, and ecosystem feedbacks under global change scenarios.
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Affiliation(s)
- Mianhai Zheng
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Zhenghu Zhou
- Center for Ecological Research, Northeast Forestry University, Harbin, China
| | - Ping Zhao
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Yiqi Luo
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
| | - Qing Ye
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Kerong Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, China
| | - Liang Song
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Xishuangbanna, China
| | - Jiangming Mo
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
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Jean M, Holland-Moritz H, Melvin AM, Johnstone JF, Mack MC. Experimental assessment of tree canopy and leaf litter controls on the microbiome and nitrogen fixation rates of two boreal mosses. New Phytol 2020; 227:1335-1349. [PMID: 32299141 DOI: 10.1111/nph.16611] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 03/16/2020] [Indexed: 06/11/2023]
Abstract
Nitrogen (N2 )-fixing moss microbial communities play key roles in nitrogen cycling of boreal forests. Forest type and leaf litter inputs regulate moss abundance, but how they control moss microbiomes and N2 -fixation remains understudied. We examined the impacts of forest type and broadleaf litter on microbial community composition and N2 -fixation rates of Hylocomium splendens and Pleurozium schreberi. We conducted a moss transplant and leaf litter manipulation experiment at three sites with paired paper birch (Betula neoalaskana) and black spruce (Picea mariana) stands in Alaska. We characterized bacterial communities using marker gene sequencing, determined N2 -fixation rates using stable isotopes (15 N2 ) and measured environmental covariates. Mosses native to and transplanted into spruce stands supported generally higher N2 -fixation and distinct microbial communities compared to similar treatments in birch stands. High leaf litter inputs shifted microbial community composition for both moss species and reduced N2 -fixation rates for H. splendens, which had the highest rates. N2 -fixation was positively associated with several bacterial taxa, including cyanobacteria. The moss microbiome and environmental conditions controlled N2 -fixation at the stand and transplant scales. Predicted shifts from spruce- to deciduous-dominated stands will interact with the relative abundances of mosses supporting different microbiomes and N2 -fixation rates, which could affect stand-level N inputs.
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Affiliation(s)
- Mélanie Jean
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
- Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
| | - Hannah Holland-Moritz
- Cooperative Institute for Research in Environmental Sciences and Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO, 80309, USA
| | - April M Melvin
- Department of Biology, University of Florida, Gainesville, FL, 32611, USA
- Independent researcher, Washington, DC, 20001, USA
| | - Jill F Johnstone
- Department of Biology, University of Saskatchewan, Saskatoon, SK, S7N 5E2, Canada
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
| | - Michelle C Mack
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
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Stuart JEM, Holland-Moritz H, Lewis LR, Jean M, Miller SN, McDaniel SF, Fierer N, Ponciano JM, Mack MC. Host Identity as a Driver of Moss-Associated N2 Fixation Rates in Alaska. Ecosystems 2020. [DOI: 10.1007/s10021-020-00534-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Carrell AA, Kolton M, Glass JB, Pelletier DA, Warren MJ, Kostka JE, Iversen CM, Hanson PJ, Weston DJ. Experimental warming alters the community composition, diversity, and N 2 fixation activity of peat moss (Sphagnum fallax) microbiomes. Glob Chang Biol 2019; 25:2993-3004. [PMID: 31148286 PMCID: PMC6852288 DOI: 10.1111/gcb.14715] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 05/17/2019] [Accepted: 05/24/2019] [Indexed: 05/19/2023]
Abstract
Sphagnum-dominated peatlands comprise a globally important pool of soil carbon (C) and are vulnerable to climate change. While peat mosses of the genus Sphagnum are known to harbor diverse microbial communities that mediate C and nitrogen (N) cycling in peatlands, the effects of climate change on Sphagnum microbiome composition and functioning are largely unknown. We investigated the impacts of experimental whole-ecosystem warming on the Sphagnum moss microbiome, focusing on N2 fixing microorganisms (diazotrophs). To characterize the microbiome response to warming, we performed next-generation sequencing of small subunit (SSU) rRNA and nitrogenase (nifH) gene amplicons and quantified rates of N2 fixation activity in Sphagnum fallax individuals sampled from experimental enclosures over 2 years in a northern Minnesota, USA bog. The taxonomic diversity of overall microbial communities and diazotroph communities, as well as N2 fixation rates, decreased with warming (p < 0.05). Following warming, diazotrophs shifted from a mixed community of Nostocales (Cyanobacteria) and Rhizobiales (Alphaproteobacteria) to predominance of Nostocales. Microbiome community composition differed between years, with some diazotroph populations persisting while others declined in relative abundance in warmed plots in the second year. Our results demonstrate that warming substantially alters the community composition, diversity, and N2 fixation activity of peat moss microbiomes, which may ultimately impact host fitness, ecosystem productivity, and C storage potential in peatlands.
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Affiliation(s)
- Alyssa A. Carrell
- Bredesen Center for Interdisciplinary Research and Graduate EducationUniversity of TennesseeKnoxvilleTennessee
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
| | - Max Kolton
- School of BiologyGeorgia Institute of TechnologyAtlantaGeorgia
| | - Jennifer B. Glass
- School of Earth and Atmospheric SciencesGeorgia Institute of TechnologyAtlantaGeorgia
| | | | - Melissa J. Warren
- School of Earth and Atmospheric SciencesGeorgia Institute of TechnologyAtlantaGeorgia
- Present address:
CH2MAtlantaGeorgia30328USA
| | - Joel E. Kostka
- School of BiologyGeorgia Institute of TechnologyAtlantaGeorgia
- School of Earth and Atmospheric SciencesGeorgia Institute of TechnologyAtlantaGeorgia
| | - Colleen M. Iversen
- Environmental Sciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
- Climate Change Science Institute, Oak Ridge National LaboratoryOak RidgeTennessee
| | - Paul J. Hanson
- Environmental Sciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
- Climate Change Science Institute, Oak Ridge National LaboratoryOak RidgeTennessee
| | - David J. Weston
- Biosciences DivisionOak Ridge National LaboratoryOak RidgeTennessee
- Climate Change Science Institute, Oak Ridge National LaboratoryOak RidgeTennessee
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16
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Zheng M, Zhou Z, Luo Y, Zhao P, Mo J. Global pattern and controls of biological nitrogen fixation under nutrient enrichment: A meta-analysis. Glob Chang Biol 2019; 25:3018-3030. [PMID: 31120621 DOI: 10.1111/gcb.14705] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 05/05/2019] [Accepted: 05/15/2019] [Indexed: 06/09/2023]
Abstract
Biological nitrogen (N) fixation (BNF), an important source of N in terrestrial ecosystems, plays a critical role in terrestrial nutrient cycling and net primary productivity. Currently, large uncertainty exists regarding how nutrient availability regulates terrestrial BNF and the drivers responsible for this process. We conducted a global meta-analysis of terrestrial BNF in response to N, phosphorus (P), and micronutrient (Micro) addition across different biomes (i.e, tropical/subtropical forest, savanna, temperate forest, grassland, boreal forest, and tundra) and explored whether the BNF responses were affected by fertilization regimes (nutrient-addition rates, duration, and total load) and environmental factors (mean annual temperature [MAT], mean annual precipitation [MAP], and N deposition). The results showed that N addition inhibited terrestrial BNF (by 19.0% (95% confidence interval [CI]: 17.7%-20.3%); hereafter), Micro addition stimulated terrestrial BNF (30.4% [25.7%-35.3%]), and P addition had an inconsistent effect on terrestrial BNF, i.e., inhibiting free-living N fixation (7.5% [4.4%-10.6%]) and stimulating symbiotic N fixation (85.5% [25.8%-158.7%]). Furthermore, the response ratios (i.e., effect sizes) of BNF to nutrient addition were smaller in low-latitude (<30°) biomes (8.5%-36.9%) than in mid-/high-latitude (≥30°) biomes (32.9%-61.3%), and the sensitivity (defined as the absolute value of response ratios) of BNF to nutrients in mid-/high-latitude biomes decreased with decreasing latitude (p ≤ 0.009; linear/logarithmic regression models). Fertilization regimes did not affect this phenomenon (p > 0.05), but environmental factors did affect it (p < 0.001) because MAT, MAP, and N deposition accounted for 5%-14%, 10%-32%, and 7%-18% of the variance in the BNF response ratios in cold (MAT < 15°C), low-rainfall (MAP < 2,500 mm), and low-N-deposition (<7 kg ha-1 year-1 ) biomes, respectively. Overall, our meta-analysis depicts a global pattern of nutrient impacts on terrestrial BNF and indicates that certain types of global change (i.e., warming, elevated precipitation and N deposition) may reduce the sensitivity of BNF in response to nutrient enrichment in mid-/high-latitude biomes.
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Affiliation(s)
- Mianhai Zheng
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhenghu Zhou
- Center for Ecological Research, Northeast Forestry University, Harbin, China
| | - Yiqi Luo
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ
| | - Ping Zhao
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Jiangming Mo
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
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17
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Graham EB, Yang F, Bell S, Hofmockel KS. High Genetic Potential for Proteolytic Decomposition in Northern Peatland Ecosystems. Appl Environ Microbiol 2019; 85:e02851-18. [PMID: 30850433 PMCID: PMC6498154 DOI: 10.1128/aem.02851-18] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 02/13/2019] [Indexed: 11/28/2022] Open
Abstract
Nitrogen (N) is a scarce nutrient commonly limiting primary productivity. Microbial decomposition of complex carbon (C) into small organic molecules (e.g., free amino acids) has been suggested to supplement biologically fixed N in northern peatlands. We evaluated the microbial (fungal, bacterial, and archaeal) genetic potential for organic N depolymerization in peatlands at Marcell Experimental Forest (MEF) in northern Minnesota. We used guided gene assembly to examine the abundance and diversity of protease genes and further compared them to those of N fixation (nifH) genes in shotgun metagenomic data collected across depths and in two distinct peatland environments (bogs and fens). Microbial protease genes greatly outnumbered nifH genes, with the most abundant genes (archaeal M1 and bacterial trypsin [S01]) each containing more sequences than all sequences attributed to nifH Bacterial protease gene assemblies were diverse and abundant across depth profiles, indicating a role for bacteria in releasing free amino acids from peptides through depolymerization of older organic material and contrasting with the paradigm of fungal dominance in depolymerization in forest soils. Although protease gene assemblies for fungi were much less abundant overall than those for bacteria, fungi were prevalent in surface samples and therefore may be vital in degrading large soil polymers from fresh plant inputs during the early stage of depolymerization. In total, we demonstrate that depolymerization enzymes from a diverse suite of microorganisms, including understudied bacterial and archaeal lineages, are prevalent within northern peatlands and likely to influence C and N cycling.IMPORTANCE Nitrogen (N) is a common limitation on primary productivity, and its source remains unresolved in northern peatlands that are vulnerable to environmental change. Decomposition of complex organic matter into free amino acids has been proposed as an important N source, but the genetic potential of microorganisms mediating this process has not been examined. Such information can inform possible responses of northern peatlands to environmental change. We show high genetic potential for microbial production of free amino acids across a range of microbial guilds in northern peatlands. In particular, the abundance and diversity of bacterial genes encoding proteolytic activity suggest a predominant role for bacteria in regulating productivity and contrasts with a paradigm of fungal dominance of organic N decomposition. Our results expand our current understanding of coupled carbon and nitrogen cycles in northern peatlands and indicate that understudied bacterial and archaeal lineages may be central in this ecosystem's response to environmental change.
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Affiliation(s)
- Emily B Graham
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Fan Yang
- Department of Agricultural & Biosystems Engineering, Iowa State University, Ames, Iowa, USA
| | - Sheryl Bell
- Pacific Northwest National Laboratory, Richland, Washington, USA
| | - Kirsten S Hofmockel
- Pacific Northwest National Laboratory, Richland, Washington, USA
- Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, Iowa, USA
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18
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Salemaa M, Lindroos AJ, Merilä P, Mäkipää R, Smolander A. N 2 fixation associated with the bryophyte layer is suppressed by low levels of nitrogen deposition in boreal forests. Sci Total Environ 2019; 653:995-1004. [PMID: 30759623 DOI: 10.1016/j.scitotenv.2018.10.364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 10/25/2018] [Accepted: 10/27/2018] [Indexed: 06/09/2023]
Abstract
Biological fixation of atmospheric nitrogen (N2) by bryophyte-associated cyanobacteria is an important source of plant-available N in the boreal biome. Information on the factors that drive biological N2 fixation (BNF) rates is needed in order to understand the N dynamics of forests under a changing climate. We assessed the potential of several cryptogam species (the feather mosses Hylocomium splendens and Pleurozium schreberi, a group of Dicranum bryophytes, two liverworts, and Cladina lichens) to serve as associates of cyanobacteria or other N2-fixing bacteria (diazotrophs) using acetylene reduction assay (ARA). We tested the hypotheses that the legacy of chronic atmospheric N deposition reduces BNF in the three bryophyte species, sampled from 12 coniferous forests located at latitudes 60-68° N in Finland. In addition, we tested the effect of moisture and temperature on BNF. All species studied showed a BNF signal in the north, with the highest rates in feather mosses. In moss samples taken along the north-south gradient with an increasing N bulk deposition from 0.8 to 4.4 kg ha-1 year-1, we found a clear decrease in BNF in both feather mosses and Dicranum group. BNF turned off at N deposition of 3-4 kg ha-1 year-1. Inorganic N (NH4-N + NO3-N) best predicted the BNF rate among regression models with different forms of N deposition as explanatory variables. However, in southern spruce stands, tree canopies modified the N in throughfall so that dissolved organic N (DON) leached from canopies compensated for inorganic N retained therein. Here, both DON and inorganic N negatively affected BNF in H. splendens. In laboratory experiments, BNF increased with increasing temperature and moisture. Our results suggest that even relatively low N deposition suppresses BNF in bryophyte-associated diazotrophs. Further, BNF could increase in northern low-deposition areas, especially if climate warming leads to moister conditions, as predicted.
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Affiliation(s)
- Maija Salemaa
- Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland.
| | - Antti-Jussi Lindroos
- Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Päivi Merilä
- Natural Resources Institute Finland (Luke), P.O. Box 413, FI-90570 Oulu, Finland
| | - Raisa Mäkipää
- Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland
| | - Aino Smolander
- Natural Resources Institute Finland (Luke), Latokartanonkaari 9, FI-00790 Helsinki, Finland
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19
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Li Y, Wu Z, Dong X, Jia Z, Sun Q. Variance in bacterial communities, potential bacterial carbon sequestration and nitrogen fixation between light and dark conditions under elevated CO 2 in mine tailings. Sci Total Environ 2019; 652:234-242. [PMID: 30366324 DOI: 10.1016/j.scitotenv.2018.10.253] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Revised: 10/19/2018] [Accepted: 10/19/2018] [Indexed: 05/20/2023]
Abstract
This study is the first to show the response of bacterial communities with primary carbon and nitrogen fixers to elevated CO2 (eCO2) in light and dark conditions based on 6 months of culture growth. Carbon sequestration and nitrogen fixation were analyzed by 13C and 15N isotope labeling using 13C-labeled CO2 and 15N-labeled N2, followed by pyrosequencing and DNA-based stable isotope probing (SIP) to identify carbon fixers and nitrogen fixers. The results indicated that eCO2 decreased the Chao 1 richness, and the eCO2-light treatment exhibited the highest Shannon diversity. In addition, eCO2 (in either light or dark conditions) greatly increased the relative abundances of bacteria belonging to the classes Betaproteobacteria and Alphaproteobacteria. The 13C atom % in the mine tailings increased from 1.108 to 1.84 ± 0.11 under light conditions and 1.52 ± 0.17 under dark conditions after 6 months of culture growth. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) form I-coding gene (cbbL) copy numbers were 164.30-fold and 40.36-fold higher than RubisCO form II-coding gene (cbbM) copy numbers in the heavy fractions with a buoyant density of 1.7388 g·mL-1 relative to the buoyant density gradients of DNA fractions obtained under eCO2-light and eCO2-dark treatment, respectively. The Proteobacteria-like cbbL genes were dominant in the carbon fixers. In addition, the 15N atom % in the mine tailings increased from 0.366 to 0.454 ± 0.021 in light conditions and 0.437 ± 0.018 in dark conditions. Furthermore, uncultured nitrogen-fixing bacteria were the dominant nitrogen fixers in light conditions, and bacteria harboring the Bradyrhizobium-like nifH and Leptospirillum-like nifH genes were the dominant nitrogen fixers in dark conditions. These first data for a mine tailing ecosystem are inconsistent with those obtained for a range of other ecosystems, in which the effects of CO2 were limited to several nonphotoautotrophic communities and different nitrogen fixers.
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Affiliation(s)
- Yang Li
- School of Resources and Environmental Engineering, Anhui University, Hefei, Anhui Province, China; State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province, China
| | - Zhaojun Wu
- School of Resources and Environmental Engineering, Anhui University, Hefei, Anhui Province, China
| | - Xingchen Dong
- College of Resources and Environmental Sciences, Gansu Agricultural University, Lanzhou, Gansu Province, China
| | - Zhongjun Jia
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province, China
| | - Qingye Sun
- School of Resources and Environmental Engineering, Anhui University, Hefei, Anhui Province, China.
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20
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21
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Holland-Moritz H, Stuart J, Lewis LR, Miller S, Mack MC, McDaniel SF, Fierer N. Novel bacterial lineages associated with boreal moss species. Environ Microbiol 2018; 20:2625-2638. [PMID: 29901277 DOI: 10.1111/1462-2920.14288] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 04/23/2018] [Accepted: 05/16/2018] [Indexed: 01/01/2023]
Abstract
Mosses are critical components of boreal ecosystems where they typically account for a large proportion of net primary productivity and harbour diverse bacterial communities that can be the major source of biologically-fixed nitrogen in these ecosystems. Despite their ecological importance, we have limited understanding of how microbial communities vary across boreal moss species and the extent to which local site conditions may influence the composition of these bacterial communities. We used marker gene sequencing to analyze bacterial communities associated with seven boreal moss species collected near Fairbanks, AK, USA. We found that host identity was more important than site in determining bacterial community composition and that mosses harbour diverse lineages of potential N2 -fixers as well as an abundance of novel taxa assigned to understudied bacterial phyla (including candidate phylum WPS-2). We performed shotgun metagenomic sequencing to assemble genomes from the WPS-2 candidate phylum and found that these moss-associated bacteria are likely anoxygenic phototrophs capable of carbon fixation via RuBisCo with an ability to utilize byproducts of photorespiration from hosts via a glyoxylate shunt. These results give new insights into the metabolic capabilities of understudied bacterial lineages that associate with mosses and the importance of plant hosts in shaping their microbiomes.
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Affiliation(s)
- Hannah Holland-Moritz
- Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO, USA.,Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO, USA
| | - Julia Stuart
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
| | - Lily R Lewis
- Department of Biology, University of Florida, Gainesville, FL, USA
| | - Samantha Miller
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
| | - Michelle C Mack
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
| | | | - Noah Fierer
- Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO, USA.,Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO, USA
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22
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Scott DL, Bradley RL, Bellenger JP, Houle D, Gundale MJ, Rousk K, DeLuca TH. Anthropogenic deposition of heavy metals and phosphorus may reduce biological N 2 fixation in boreal forest mosses. Sci Total Environ 2018; 630:203-210. [PMID: 29477819 DOI: 10.1016/j.scitotenv.2018.02.192] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 02/15/2018] [Accepted: 02/16/2018] [Indexed: 06/08/2023]
Abstract
A study was undertaken to test the effects of molybdenum (Mo) and phosphorus (P) amendments on biological nitrogen (N) fixation (BNF) by boreal forest moss-associated cyanobacteria. Feather moss (Pleurozium schreberi) samples were collected on five sites, on two dates and at different roadside distances (0-100m) corresponding to an assumed gradient of reactive N deposition. Potential BNF of Mo and P amended moss samples was measured using the acetylene reduction assay. Total N, P and heavy metal concentrations of mosses collected at 0 and 100m from roadsides were also measured. Likewise, the needles from Norway spruce trees (Picea abies) at different roadside distances were collected in late summer and analyzed for total N, P and heavy metals. There was a significant increase in BNF with roadside distance on 7-of-10 individual Site×Date combinations. We found no clear evidence of an N gradient across roadside distances. Elemental analyses of feather moss and Norway spruce needle tissues suggested decreasing deposition of heavy metals (Mo-Co-Cr-Ni-V-Pb-Ag-Cu) as well as P with increasing distance from the roadside. The effects of Mo and P amendments on BNF were infrequent and inconsistent across roadside distances and across sites. One particular site, however, displayed greater concentrations of heavy metals near the roadside, as well as a steeper P fertility gradient with roadside distance, than the other sites. Here, BNF increased with roadside distance only when moss samples were amended with P. Also at this site, BNF across all roadside distances was higher when mosses were amended with both Mo and P, suggesting a co-limitation of these two nutrients in controlling BNF. In summary, our study showed a potential for car emissions to increase heavy metals and P along roadsides and underscored the putative roles of these anthropogenic pollutants on BNF in northern latitudes.
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Affiliation(s)
- Dalton L Scott
- Université de Sherbrooke, Département de Biologie, Sherbrooke, Canada
| | - Robert L Bradley
- Université de Sherbrooke, Département de Biologie, Sherbrooke, Canada.
| | | | - Daniel Houle
- Ministère des Forêts, de la Faune et des Parcs, Québec, Canada
| | - Michael J Gundale
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Kathrin Rousk
- Department of Biology, University of Copenhagen, Denmark; Center for Permafrost (CENPERM), University of Copenhagen, Denmark
| | - Thomas H DeLuca
- Franke College of Forestry and Conservation, University of Montana, Missoula, MT, United States
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23
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Liu S, Liu W, Shi X, Li S, Hu T, Song L, Wu C. Dry-hot stress significantly reduced the nitrogenase activity of epiphytic cyanolichen. Sci Total Environ 2018; 619-620:630-637. [PMID: 29156281 DOI: 10.1016/j.scitotenv.2017.11.179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 11/15/2017] [Accepted: 11/15/2017] [Indexed: 06/07/2023]
Abstract
Nitrogen (N) fixed by epiphytic cyanolichens (i.e. lichens that contain cyanobacterial symbionts) is thought to be the most important resource of this nutrient in some natural forest ecosystems. Although a great deal of work has been carried out to evaluate the biomass of this group as well as its contribution to ecosystem N budgets, empirical studies are needed to confirm the N input responses by cyanolichens under climate change conditions (dry-hot stress) as well as to determine the factors that control this process. We simulated climate change conditions by transplanting Lobaria retigera, a common cyanolichen in the area, to lower elevations, and measured nitrogenase activity in response to warmer and drier conditions. In addition, we conducted a series of laboratory and greenhouse experiments to determine the dominant factors influencing nitrogenase activity in this species. The results of this study show that mean annual nitrogenase activity at the higher site was 1.5 and 2.4 times that at the simulated warmer and drier (middle and lower) sites, respectively. Combining laboratory experimental conclusions, we show that thallus water content is a key factor determining the nitrogenase activity of L. retigera in early transplantation while insufficient carbon storage resulting from a combination of warming and desiccation was likely responsible for reducing nitrogenase activity in later months of the transplant experiment. The results of this study imply that the negative impact of climate change (dry-hot stress) on ecosystems not only impacts the distribution and growth of species, but also nutrient circles and budgets.
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Affiliation(s)
- Shuai Liu
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Wenyao Liu
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, PR China.
| | - Xianmeng Shi
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Su Li
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, PR China
| | - Tao Hu
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Liang Song
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, PR China
| | - Chuansheng Wu
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming, Yunnan 650223, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Ailaoshan Station for Subtropical Forest Ecosystem Studies, Jingdong 676209, PR China
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Affiliation(s)
- Kathrin Rousk
- Department of Biology; Terrestrial Ecology Section; University of Copenhagen; Universitetsparken 15 2100 Copenhagen Denmark
- Center for Permafrost (CENPERM); University of Copenhagen; Øster Voldgade 10 1350 Copenhagen Denmark
| | - Pernille Laerkedal Sorensen
- Department of Biology; Terrestrial Ecology Section; University of Copenhagen; Universitetsparken 15 2100 Copenhagen Denmark
| | - Anders Michelsen
- Department of Biology; Terrestrial Ecology Section; University of Copenhagen; Universitetsparken 15 2100 Copenhagen Denmark
- Center for Permafrost (CENPERM); University of Copenhagen; Øster Voldgade 10 1350 Copenhagen Denmark
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25
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Rousk K, Degboe J, Michelsen A, Bradley R, Bellenger JP. Molybdenum and phosphorus limitation of moss-associated nitrogen fixation in boreal ecosystems. New Phytol 2017; 214:97-107. [PMID: 27883187 DOI: 10.1111/nph.14331] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/15/2016] [Indexed: 05/27/2023]
Abstract
Biological nitrogen fixation (BNF) performed by moss-associated cyanobacteria is one of the main sources of new nitrogen (N) input in pristine, high-latitude ecosystems. Yet, the nutrients that limit BNF remain elusive. Here, we tested whether this important ecosystem function is limited by the availability of molybdenum (Mo), phosphorus (P), or both. BNF in dominant mosses was measured with the acetylene reduction assay (ARA) at different time intervals following Mo and P additions, in both laboratory microcosms with mosses from a boreal spruce forest and field plots in subarctic tundra. We further used a 15 N2 tracer technique to assess the ARA to N2 fixation conversion ratios at our subarctic site. BNF was up to four-fold higher shortly after the addition of Mo, in both the laboratory and field experiments. A similar positive response to Mo was found in moss colonizing cyanobacterial biomass. As the growing season progressed, nitrogenase activity became progressively more P limited. The ARA : 15 N2 ratios increased with increasing Mo additions. These findings show that N2 fixation activity as well as cyanobacterial biomass in dominant feather mosses from boreal forests and subarctic tundra are limited by Mo availability.
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Affiliation(s)
- Kathrin Rousk
- Department of Biology, Terrestrial Ecology Section, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark
- Center for Permafrost (CENPERM), University of Copenhagen, Øster Voldgade 10, 1350, Copenhagen, Denmark
| | - Jefferson Degboe
- Centre Sève, Département de Chimie, Université de Sherbrooke, Sherbrooke, J1K 2R1, QC, Canada
| | - Anders Michelsen
- Department of Biology, Terrestrial Ecology Section, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark
- Center for Permafrost (CENPERM), University of Copenhagen, Øster Voldgade 10, 1350, Copenhagen, Denmark
| | - Robert Bradley
- Département de Biologie, Université de Sherbrooke, Sherbrooke, J1K 2R1, QC, Canada
| | - Jean-Philippe Bellenger
- Centre Sève, Département de Chimie, Université de Sherbrooke, Sherbrooke, J1K 2R1, QC, Canada
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Lindo Z, Griffith D. Elevated Atmospheric CO2 and Warming Stimulates Growth and Nitrogen Fixation in a Common Forest Floor Cyanobacterium under Axenic Conditions. Forests 2017; 8:73. [DOI: 10.3390/f8030073] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Warshan D, Bay G, Nahar N, Wardle DA, Nilsson MC, Rasmussen U. Seasonal variation in nifH abundance and expression of cyanobacterial communities associated with boreal feather mosses. ISME J 2016; 10:2198-208. [PMID: 26918665 PMCID: PMC4989308 DOI: 10.1038/ismej.2016.17] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Revised: 12/16/2015] [Accepted: 01/08/2016] [Indexed: 11/13/2022]
Abstract
Dinitrogen (N2)-fixation by cyanobacteria living in symbiosis with pleurocarpous feather mosses (for example, Pleurozium schreberi and Hylocomium splendens) represents the main pathway of biological N input into N-depleted boreal forests. Little is known about the role of the cyanobacterial community in contributing to the observed temporal variability of N2-fixation. Using specific nifH primers targeting four major cyanobacterial clusters and quantitative PCR, we investigated how community composition, abundance and nifH expression varied by moss species and over the growing seasons. We evaluated N2-fixation rates across nine forest sites in June and September and explored the abundance and nifH expression of individual cyanobacterial clusters when N2-fixation is highest. Our results showed temporal and host-dependent variations of cyanobacterial community composition, nifH gene abundance and expression. N2-fixation was higher in September than June for both moss species, explained by higher nifH gene expression of individual clusters rather than higher nifH gene abundance or differences in cyanobacterial community composition. In most cases, 'Stigonema cluster' made up less than 29% of the total cyanobacterial community, but accounted for the majority of nifH gene expression (82-94% of total nifH expression), irrespective of sampling date or moss species. Stepwise multiple regressions showed temporal variations in N2-fixation being greatly explained by variations in nifH expression of the 'Stigonema cluster'. These results suggest that Stigonema is potentially the most influential N2-fixer in symbiosis with boreal forest feather mosses.
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Affiliation(s)
- Denis Warshan
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Guillaume Bay
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Nurun Nahar
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - David A Wardle
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Marie-Charlotte Nilsson
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Ulla Rasmussen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
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Kardol P, Spitzer CM, Gundale MJ, Nilsson MC, Wardle DA. Trophic cascades in the bryosphere: the impact of global change factors on top-down control of cyanobacterial N2-fixation. Ecol Lett 2016; 19:967-76. [DOI: 10.1111/ele.12635] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 05/04/2016] [Accepted: 05/17/2016] [Indexed: 11/26/2022]
Affiliation(s)
- Paul Kardol
- Department of Forest Ecology and Management; Swedish University of Agricultural Sciences; 901 83 Umeå Sweden
| | - Clydecia M. Spitzer
- Department of Forest Ecology and Management; Swedish University of Agricultural Sciences; 901 83 Umeå Sweden
| | - Michael J. Gundale
- Department of Forest Ecology and Management; Swedish University of Agricultural Sciences; 901 83 Umeå Sweden
| | - Marie-Charlotte Nilsson
- Department of Forest Ecology and Management; Swedish University of Agricultural Sciences; 901 83 Umeå Sweden
| | - David A. Wardle
- Department of Forest Ecology and Management; Swedish University of Agricultural Sciences; 901 83 Umeå Sweden
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Whiteley JA, Gonzalez A. Biotic nitrogen fixation in the bryosphere is inhibited more by drought than warming. Oecologia 2016; 181:1243-58. [DOI: 10.1007/s00442-016-3601-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 03/03/2016] [Indexed: 11/30/2022]
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Cowles JM, Wragg PD, Wright AJ, Powers JS, Tilman D. Shifting grassland plant community structure drives positive interactive effects of warming and diversity on aboveground net primary productivity. Glob Chang Biol 2016; 22:741-749. [PMID: 26426698 DOI: 10.1111/gcb.13111] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 08/20/2015] [Accepted: 09/05/2015] [Indexed: 06/05/2023]
Abstract
Ecosystems worldwide are increasingly impacted by multiple drivers of environmental change, including climate warming and loss of biodiversity. We show, using a long-term factorial experiment, that plant diversity loss alters the effects of warming on productivity. Aboveground primary productivity was increased by both high plant diversity and warming, and, in concert, warming (≈1.5 °C average above and belowground warming over the growing season) and diversity caused a greater than additive increase in aboveground productivity. The aboveground warming effects increased over time, particularly at higher levels of diversity, perhaps because of warming-induced increases in legume and C4 bunch grass abundances, and facilitative feedbacks of these species on productivity. Moreover, higher plant diversity was associated with the amelioration of warming-induced environmental conditions. This led to cooler temperatures, decreased vapor pressure deficit, and increased surface soil moisture in higher diversity communities. Root biomass (0-30 cm) was likewise consistently greater at higher plant diversity and was greater with warming in monocultures and at intermediate diversity, but at high diversity warming had no detectable effect. This may be because warming increased the abundance of legumes, which have lower root : shoot ratios than the other types of plants. In addition, legumes increase soil nitrogen (N) supply, which could make N less limiting to other species and potentially decrease their investment in roots. The negative warming × diversity interaction on root mass led to an overall negative interactive effect of these two global change factors on the sum of above and belowground biomass, and thus likely on total plant carbon stores. In total, plant diversity increased the effect of warming on aboveground net productivity and moderated the effect on root mass. These divergent effects suggest that warming and changes in plant diversity are likely to have both interactive and divergent impacts on various aspects of ecosystem functioning.
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Affiliation(s)
- Jane M Cowles
- Department of Ecology, Evolution & Behavior, University of Minnesota Twin Cities, Saint Paul, MN, 55108, USA
| | - Peter D Wragg
- Department of Ecology, Evolution & Behavior, University of Minnesota Twin Cities, Saint Paul, MN, 55108, USA
| | | | - Jennifer S Powers
- Department of Ecology, Evolution & Behavior, University of Minnesota Twin Cities, Saint Paul, MN, 55108, USA
- Department of Plant Biology, University of Minnesota Twin Cities, Saint Paul, MN, 55108, USA
| | - David Tilman
- Department of Ecology, Evolution & Behavior, University of Minnesota Twin Cities, Saint Paul, MN, 55108, USA
- Bren School of the Environment, University of California, Santa Barbara, CA, 93106, USA
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Rousk K, Sorensen PL, Lett S, Michelsen A. Across-habitat comparison of diazotroph activity in the subarctic. Microb Ecol 2015; 69:778-87. [PMID: 25403111 DOI: 10.1007/s00248-014-0534-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 11/03/2014] [Indexed: 05/03/2023]
Abstract
Nitrogen (N) fixation by N2-fixing bacteria (diazotrophs) is the primary N input to pristine ecosystems like boreal forests and subarctic and arctic tundra. However, the contribution by the various diazotrophs to habitat N2 fixation remains unclear. We present results from in situ assessments of N2 fixation of five diazotroph associations (with a legume, lichen, feather moss, Sphagnum moss and free-living) incorporating the ground cover of the associations in five typical habitats in the subarctic (wet and dry heath, polygon-heath, birch forest, mire). Further, we assessed the importance of soil and air temperature, as well as moisture conditions for N2 fixation. Across the growing season, the legume had the highest total as well as the highest fraction of N2 fixation rates at habitat level in the heaths (>85 % of habitat N2 fixation), whereas the free-living diazotrophs had the highest N2 fixation rates in the polygon heath (56 %), the lichen in the birch forest (87 %) and Sphagnum in the mire (100 %). The feather moss did not contribute more than 15 % to habitat N2 fixation in any of the habitats despite its high ground cover. Moisture content seemed to be a major driver of N2 fixation in the lichen, feather moss and free-living diazotrophs. Our results show that the range of N2 fixers found in pristine habitats contribute differently to habitat N2 fixation and that ground cover of the associates does not necessarily mirror contribution.
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Affiliation(s)
- Kathrin Rousk
- Department of Biology, Terrestrial Ecology Section, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark,
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Hedwall PO, Skoglund J, Linder S. Interactions with successional stage and nutrient status determines the life-form-specific effects of increased soil temperature on boreal forest floor vegetation. Ecol Evol 2015; 5:948-60. [PMID: 25750720 PMCID: PMC4338976 DOI: 10.1002/ece3.1412] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 01/06/2015] [Indexed: 11/10/2022] Open
Abstract
The boreal forest is one of the largest terrestrial biomes and plays a key role for the global carbon balance and climate. The forest floor vegetation has a strong influence on the carbon and nitrogen cycles of the forests and is sensitive to changes in temperature conditions and nutrient availability. Additionally, the effects of climate warming on forest floor vegetation have been suggested to be moderated by the tree layer. Data on the effects of soil warming on forest floor vegetation from the boreal forest are, however, very scarce. We studied the effects on the forest floor vegetation in a long-term (18 years) soil warming and fertilization experiment in a Norway spruce stand in northern Sweden. During the first 9 years, warming favored early successional species such as grasses and forbs at the expense of dwarf shrubs and bryophytes in unfertilized stands, while the effects were smaller after fertilization. Hence, warming led to significant changes in species composition and an increase in species richness in the open canopy nutrient limited forest. After another 9 years of warming and increasing tree canopy closure, most of the initial effects had ceased, indicating an interaction between forest succession and warming. The only remaining effect of warming was on the abundance of bryophytes, which contrary to the initial phase was strongly favored by warming. We propose that the suggested moderating effects of the tree layer are specific to plant life-form and conclude that the successional phase of the forest may have a considerable impact on the effects of climate change on forest floor vegetation and its feedback effects on the carbon and nitrogen cycles, and thus on the climate.
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Affiliation(s)
- Per-Ola Hedwall
- Swedish University of Agricultural Sciences, SLU, Southern Swedish Forest Research Centre PO Box 49, SE-230 53, Alnarp, Sweden
| | | | - Sune Linder
- Swedish University of Agricultural Sciences, SLU, Southern Swedish Forest Research Centre PO Box 49, SE-230 53, Alnarp, Sweden
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Jonsson M, Kardol P, Gundale MJ, Bansal S, Nilsson MC, Metcalfe DB, Wardle DA. Direct and Indirect Drivers of Moss Community Structure, Function, and Associated Microfauna Across a Successional Gradient. Ecosystems 2014. [DOI: 10.1007/s10021-014-9819-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Stuiver B, Wardle D, Gundale M, Nilsson M. The Impact of Moss Species and Biomass on the Growth of Pinus sylvestris Tree Seedlings at Different Precipitation Frequencies. Forests 2014; 5:1931-51. [DOI: 10.3390/f5081931] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Arróniz-Crespo M, Pérez-Ortega S, De los Ríos A, Green TGA, Ochoa-Hueso R, Casermeiro MÁ, de la Cruz MT, Pintado A, Palacios D, Rozzi R, Tysklind N, Sancho LG. Bryophyte-cyanobacteria associations during primary succession in recently Deglaciated areas of Tierra del Fuego (Chile). PLoS One 2014; 9:e96081. [PMID: 24819926 PMCID: PMC4018330 DOI: 10.1371/journal.pone.0096081] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 04/02/2014] [Indexed: 11/18/2022] Open
Abstract
Bryophyte establishment represents a positive feedback process that enhances soil development in newly exposed terrain. Further, biological nitrogen (N) fixation by cyanobacteria in association with mosses can be an important supply of N to terrestrial ecosystems, however the role of these associations during post-glacial primary succession is not yet fully understood. Here, we analyzed chronosequences in front of two receding glaciers with contrasting climatic conditions (wetter vs drier) at Cordillera Darwin (Tierra del Fuego) and found that most mosses had the capacity to support an epiphytic flora of cyanobacteria and exhibited high rates of N2 fixation. Pioneer moss-cyanobacteria associations showed the highest N2 fixation rates (4.60 and 4.96 µg N g−1 bryo. d−1) very early after glacier retreat (4 and 7 years) which may help accelerate soil development under wetter conditions. In drier climate, N2 fixation on bryophyte-cyanobacteria associations was also high (0.94 and 1.42 µg N g−1 bryo. d−1) but peaked at intermediate-aged sites (26 and 66 years). N2 fixation capacity on bryophytes was primarily driven by epiphytic cyanobacteria abundance rather than community composition. Most liverworts showed low colonization and N2 fixation rates, and mosses did not exhibit consistent differences across life forms and habitat (saxicolous vs terricolous). We also found a clear relationship between cyanobacteria genera and the stages of ecological succession, but no relationship was found with host species identity. Glacier forelands in Tierra del Fuego show fast rates of soil transformation which imply large quantities of N inputs. Our results highlight the potential contribution of bryophyte-cyanobacteria associations to N accumulation during post-glacial primary succession and further describe the factors that drive N2-fixation rates in post-glacial areas with very low N deposition.
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Affiliation(s)
- María Arróniz-Crespo
- Dept. de Biología Vegetal II, Universidad Complutense de Madrid, Madrid, Spain
- School of Environment Natural Resources and Geography, Bangor University, Bangor, Wales, United Kingdom
- * E-mail:
| | - Sergio Pérez-Ortega
- Dept. de Biología Ambiental, Museo Nacional de Ciencias Naturales, MNCN-CSIC, Madrid, Spain
| | - Asunción De los Ríos
- Dept. de Biología Ambiental, Museo Nacional de Ciencias Naturales, MNCN-CSIC, Madrid, Spain
| | - T. G. Allan Green
- Dept. de Biología Vegetal II, Universidad Complutense de Madrid, Madrid, Spain
- Biological Sciences, Waikato University, Hamilton, New Zealand
| | - Raúl Ochoa-Hueso
- Dept. de Biogeografía y Cambio Global, Museo Nacional de Ciencias Naturales, Madrid, Spain
| | | | | | - Ana Pintado
- Dept. de Biología Vegetal II, Universidad Complutense de Madrid, Madrid, Spain
| | - David Palacios
- Departamento Geografía Física, Universidad Complutense de Madrid, Madrid, Spain
| | - Ricardo Rozzi
- Sub-Antarctic Biocultural Conservation Program, University of North Texas, Denton, Texas, United States of America
- Institute of Ecology and Biodiversity, Universidad de Magallanes, Puerto Williams, Chile
| | - Niklas Tysklind
- School of Biological Sciences, Bangor University, Bangor, Wales, United Kingdom
| | - Leopoldo G. Sancho
- Dept. de Biología Vegetal II, Universidad Complutense de Madrid, Madrid, Spain
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Gundale MJ, Bach LH, Nordin A. The impact of simulated chronic nitrogen deposition on the biomass and N₂-fixation activity of two boreal feather moss-cyanobacteria associations. Biol Lett 2013; 9:20130797. [PMID: 24196519 DOI: 10.1098/rsbl.2013.0797] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bryophytes achieve substantial biomass and play several key functional roles in boreal forests that can influence how carbon (C) and nitrogen (N) cycling respond to atmospheric deposition of reactive nitrogen (Nr). They associate with cyanobacteria that fix atmospheric N₂, and downregulation of this process may offset anthropogenic Nr inputs to boreal systems. Bryophytes also promote soil C accumulation by thermally insulating soils, and changes in their biomass influence soil C dynamics. Using a unique large-scale (0.1 ha forested plots), long-term experiment (16 years) in northern Sweden where we simulated anthropogenic Nr deposition, we measured the biomass and N₂-fixation response of two bryophyte species, the feather mosses Hylocomium splendens and Pleurozium schreberi. Our data show that the biomass declined for both species; however, N₂-fixation rates per unit mass and per unit area declined only for H. splendens. The low and high treatments resulted in a 29% and 54% reduction in total feather moss biomass, and a 58% and 97% reduction in total N₂-fixation rate per unit area, respectively. These results help to quantify the sensitivity of feather moss biomass and N₂ fixation to chronic Nr deposition, which is relevant for modelling ecosystem C and N balances in boreal ecosystems.
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Affiliation(s)
- Michael J Gundale
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, , Umeå 90183, Sweden
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Lindo Z, Nilsson MC, Gundale MJ. Bryophyte-cyanobacteria associations as regulators of the northern latitude carbon balance in response to global change. Glob Chang Biol 2013; 19:2022-35. [PMID: 23505142 DOI: 10.1111/gcb.12175] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 01/17/2013] [Accepted: 01/23/2013] [Indexed: 05/03/2023]
Abstract
Ecosystems in the far north, including arctic and boreal biomes, are a globally significant pool of carbon (C). Global change is proposed to influence both C uptake and release in these ecosystems, thereby potentially affecting whether they act as C sources or sinks. Bryophytes (i.e., mosses) serve a variety of key functions in these systems, including their association with nitrogen (N2 )-fixing cyanobacteria, as thermal insulators of the soil, and producers of recalcitrant litter, which have implications for both net primary productivity (NPP) and heterotrophic respiration. While ground-cover bryophytes typically make up a small proportion of the total biomass in northern systems, their combined physical structure and N2 -fixing capabilities facilitate a disproportionally large impact on key processes that control ecosystem C and N cycles. As such, the response of bryophyte-cyanobacteria associations to global change may influence whether and how ecosystem C balances are influenced by global change. Here, we review what is known about their occurrence and N2 -fixing activity, and how bryophyte systems will respond to several key global change factors. We explore the implications these responses may have in determining how global change influences C balances in high northern latitudes.
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Affiliation(s)
- Zoë Lindo
- Department of Biology, Western University, London, ON, Canada.
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Rousk K, Jones DL, DeLuca TH. Moss-cyanobacteria associations as biogenic sources of nitrogen in boreal forest ecosystems. Front Microbiol 2013; 4:150. [PMID: 23785359 PMCID: PMC3683619 DOI: 10.3389/fmicb.2013.00150] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 05/28/2013] [Indexed: 01/05/2023] Open
Abstract
The biological fixation of atmospheric nitrogen (N) is a major pathway for available N entering ecosystems. In N-limited boreal forests, a significant amount of N2 is fixed by cyanobacteria living in association with mosses, contributing up to 50% to the total N input. In this review, we synthesize reports on the drivers of N2 fixation in feather moss-cyanobacteria associations to gain a deeper understanding of their role for ecosystem-N-cycling. Nitrogen fixation in moss-cyanobacteria associations is inhibited by N inputs and therefore, significant fixation occurs only in low N-deposition areas. While it has been shown that artificial N additions in the laboratory as well as in the field inhibit N2 fixation in moss-cyanobacteria associations, the type, as well as the amounts of N that enters the system, affect N2 fixation differently. Another major driver of N2 fixation is the moisture status of the cyanobacteria-hosting moss, wherein moist conditions promote N2 fixation. Mosses experience large fluctuations in their hydrological status, undergoing significant natural drying and rewetting cycles over the course of only a few hours, especially in summer, which likely compromises the N input to the system via N2 fixation. Perhaps the most central question, however, that remains unanswered is the fate of the fixed N2 in mosses. The cyanobacteria are likely to leak N, but whether this N is transferred to the soil and if so, at which rates and timescales, is unknown. Despite our increasing understanding of the drivers of N2 fixation, the role moss-cyanobacteria associations play in ecosystem-N-cycling remains unresolved. Further, the relationship mosses and cyanobacteria share is unknown to date and warrants further investigation.
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Affiliation(s)
- Kathrin Rousk
- School of Environment, Natural Resources and Geography, Bangor UniversityBangor, Gwynedd, UK
| | - Davey L. Jones
- School of Environment, Natural Resources and Geography, Bangor UniversityBangor, Gwynedd, UK
| | - Thomas H. DeLuca
- School of Environment and Forest Sciences, University of WashingtonSeattle, WA, USA
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Abstract
Plant productivity is predicted to increase in boreal forests owing to climate change, but this may depend on whether N inputs from biological N-fixation also increases. We evaluated how alteration of climatic factors affects N input from a widespread boreal N-fixer, i.e. cyanobacteria associated with the feather moss Pleurozium schreberi. In each of 10 forest stands in northern Sweden, we established climate-change plots, including a control (ambient climate) plot and three plots experiencing a +2°C temperature increase, an approximately threefold reduction in precipitation frequency, and either 0.07, 0.29 or 1.16 times normal summer precipitation. We monitored N-fixation in these plots five times between 2007 and 2009, and three times in 2010 after climate treatments ended to assess their recovery. Warmer temperatures combined with less frequent precipitation reduced feather moss moisture content and N-fixation rates regardless of total precipitation. After climate treatments ended, recovery of N-fixation rates occurred on the scale of weeks to months, suggesting resilience of N-fixation to changes in climatic conditions. These results suggest that modelling of biological N-inputs in boreal forests should emphasize precipitation frequency and evaporative water loss in conjunction with elevated temperature rather than absolute changes in mean precipitation.
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Affiliation(s)
- Michael J Gundale
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901-83 Umeå, Sweden.
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