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  1. Article ; Online: Shade and drought increase fungal contribution to partially mycoheterotrophic terrestrial orchids Goodyera pubescens and Tipularia discolor

    Melissa K. McCormick / Kerry L. Good / Thomas J. Mozdzer / Dennis F. Whigham

    Frontiers in Ecology and Evolution, Vol

    2022  Volume 10

    Abstract: Many photosynthetic plants supplement photosynthetic carbon with fungal carbon, but the mechanisms that govern dependence on mycoheterotrophic carbon are poorly understood. We used exclusion shelters to manipulate water and light availability to plants ... ...

    Abstract Many photosynthetic plants supplement photosynthetic carbon with fungal carbon, but the mechanisms that govern dependence on mycoheterotrophic carbon are poorly understood. We used exclusion shelters to manipulate water and light availability to plants of the terrestrial orchids Goodyera pubescens and Tipularia discolor. We tracked changes in δ13C from photosynthesis and δ15N acquired from soil-derived inorganic nitrogen versus mycoheterotrophy, along with direct measures of photosynthesis in T. discolor. We hypothesized that shade would increase dependence on mycoheterotrophy compared to reference plants, while drought would decrease both photosynthesis and the abundance of potential mycorrhizal fungi. Drought and shade enriched 13C and 15N in both G. pubescens and T. discolor, compared to control plants, indicating increased fungal contribution to orchid tissues. Physiological measurements of T. discolor leaves showed that dark respiration, water use efficiency, and relative electron transport rate did not vary significantly, but shaded plants had greater quantum efficiency, suggesting they were light-limited. Light saturated photosynthesis of T. discolor leaves was lower in both shaded and drought-treated plants, indicating lower photosynthetic capacity, and likely greater dependence on mycoheterotrophy and corresponding enrichment in 13C and 15N. This study documented changes in orchid dependence on fungal carbon in response to manipulated environmental conditions. Both shade and drought increased the dependence of both orchids on mycoheterotrophically derived carbon and nitrogen.
    Keywords Goodyera pubescens ; Tipularia discolor ; mycoheterotrophy ; orchid ; mycorrhizae ; stable isotope ; Evolution ; QH359-425 ; Ecology ; QH540-549.5
    Subject code 580
    Language English
    Publishing date 2022-11-01T00:00:00Z
    Publisher Frontiers Media S.A.
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Author Correction

    Peter Mueller / Thomas J. Mozdzer / J. Adam Langley / Lillian R. Aoki / Genevieve L. Noyce / J. Patrick Megonigal

    Nature Communications, Vol 14, Iss 1, Pp 1-

    Plant species determine tidal wetland methane response to sea level rise

    2023  Volume 1

    Keywords Science ; Q
    Language English
    Publishing date 2023-03-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Suitability of Wild Phragmites australis as Bio-Resource

    Franziska Eller / Xiao Guo / Siyuan Ye / Thomas J. Mozdzer / Hans Brix

    Resources, Vol 9, Iss 143, p

    Tissue Quality and Morphology of Populations from Three Continents

    2020  Volume 143

    Abstract: We collected and analyzed morphological characteristics and tissue nutrient concentrations of common reed ( Phragmites australis ) populations from Denmark, USA, and China, harvested late summer at the peak of the biomass production. The aim was to ... ...

    Abstract We collected and analyzed morphological characteristics and tissue nutrient concentrations of common reed ( Phragmites australis ) populations from Denmark, USA, and China, harvested late summer at the peak of the biomass production. The aim was to estimate the suitability of the biomass for different bioenergy purposes. The potential of reed as bioenergy feedstock is increasingly recognized, as the species already is utilized for construction, water purification, and pulp production. Our morphological data showed that biomass yield can be allometrically predicted to be high, especially in the reed populations of the US. However, no consistent pattern according to geographical origin was detected, and especially tissue nutrient concentrations varied within and between populations. Some mineral concentrations were above the desirable threshold for biocombustion, such as nitrogen (N) and sulfur (S). Iron (Fe) was higher than the critical toxicity concentration in many populations and hence, negatively correlated with morphological and growth traits. A different harvest time is likely to result in lower ion concentrations. Some populations had low C to N ratios, which are suitable for biomethane production, while the relatively low ash content of all populations (ranging from 3.9% to 8.5%) suggested a high heating value and theoretical energy potential. Reed biomass production is a promising alternative to fossil fuels and potentially suitable for other bio-based product. Improved knowledge is needed to examine local needs and application possibilities for reed biomass.
    Keywords biocombustion ; biomethane ; nutrient concentration ; paludiculture ; invasive reed ; Science ; Q
    Subject code 580
    Language English
    Publishing date 2020-12-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  4. Article: An invasive wetland grass primes deep soil carbon pools

    Bernal, Blanca / J. Patrick Megonigal / Thomas J. Mozdzer

    Global change biology. 2017 May, v. 23, no. 5

    2017  

    Abstract: Understanding the processes that control deep soil carbon (C) dynamics and accumulation is of key importance, given the relevance of soil organic matter (SOM) as a vast C pool and climate change buffer. Methodological constraints of measuring SOM ... ...

    Abstract Understanding the processes that control deep soil carbon (C) dynamics and accumulation is of key importance, given the relevance of soil organic matter (SOM) as a vast C pool and climate change buffer. Methodological constraints of measuring SOM decomposition in the field prevent the addressing of real‐time rhizosphere effects that regulate nutrient cycling and SOM decomposition. An invasive lineage of Phragmites australis roots deeper than native vegetation (Schoenoplectus americanus and Spartina patens) in coastal marshes of North America and has potential to dramatically alter C cycling and accumulation in these ecosystems. To evaluate the effect of deep rooting on SOM decomposition we designed a mesocosm experiment that differentiates between plant‐derived, surface SOM‐derived (0–40 cm, active root zone of native marsh vegetation), and deep SOM‐derived mineralization (40–80 cm, below active root zone of native vegetation). We found invasive P. australis allocated the highest proportion of roots in deeper soils, differing significantly from the native vegetation in root : shoot ratio and belowground biomass allocation. About half of the CO₂ produced came from plant tissue mineralization in invasive and native communities; the rest of the CO₂ was produced from SOM mineralization (priming). Under P. australis, 35% of the CO₂ was produced from deep SOM priming and 9% from surface SOM. In the native community, 9% was produced from deep SOM priming and 44% from surface SOM. SOM priming in the native community was proportional to belowground biomass, while P. australis showed much higher priming with less belowground biomass. If P. australis deep rooting favors the decomposition of deep‐buried SOM accumulated under native vegetation, P. australis invasion into a wetland could fundamentally change SOM dynamics and lead to the loss of the C pool that was previously sequestered at depth under the native vegetation, thereby altering the function of a wetland as a long‐term C sink.
    Keywords Phragmites australis ; Schoenoplectus americanus ; Spartina patens ; belowground biomass ; biogeochemical cycles ; carbon ; carbon dioxide ; carbon sinks ; climate change ; coasts ; dry matter partitioning ; ecosystems ; grasses ; indigenous species ; invasive species ; marshes ; mineralization ; plant tissues ; rhizosphere ; rooting ; roots ; soil ; soil organic matter ; vegetation ; North America
    Language English
    Dates of publication 2017-05
    Size p. 2104-2116.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 1281439-8
    ISSN 1365-2486 ; 1354-1013
    ISSN (online) 1365-2486
    ISSN 1354-1013
    DOI 10.1111/gcb.13539
    Database NAL-Catalogue (AGRICOLA)

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  5. Article ; Online: Plant species determine tidal wetland methane response to sea level rise

    Peter Mueller / Thomas J. Mozdzer / J. Adam Langley / Lillian R. Aoki / Genevieve L. Noyce / J. Patrick Megonigal

    Nature Communications, Vol 11, Iss 1, Pp 1-

    2020  Volume 9

    Abstract: Coastal systems have enormous carbon-sequestering potential, but any positive climate effects can be countered by methane emissions. Here the authors use sea level rise manipulation mesocosms in tidal wetlands to show that shifts in plant community ... ...

    Abstract Coastal systems have enormous carbon-sequestering potential, but any positive climate effects can be countered by methane emissions. Here the authors use sea level rise manipulation mesocosms in tidal wetlands to show that shifts in plant community composition have the greatest effect on methane emissions.
    Keywords Science ; Q
    Language English
    Publishing date 2020-10-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Jack-and-master trait responses to elevated CO2 and N

    Thomas J Mozdzer / J Patrick Megonigal

    PLoS ONE, Vol 7, Iss 10, p e

    a comparison of native and introduced Phragmites australis.

    2012  Volume 42794

    Abstract: Global change is predicted to promote plant invasions world-wide, reducing biodiversity and ecosystem function. Phenotypic plasticity may influence the ability of introduced plant species to invade and dominate extant communities. However, interpreting ... ...

    Abstract Global change is predicted to promote plant invasions world-wide, reducing biodiversity and ecosystem function. Phenotypic plasticity may influence the ability of introduced plant species to invade and dominate extant communities. However, interpreting differences in plasticity can be confounded by phylogenetic differences in morphology and physiology. Here we present a novel case investigating the role of fitness trait values and phenotypic plasticity to global change factors between conspecific lineages of Phragmites australis. We hypothesized that due to observed differences in the competitive success of North American-native and Eurasian-introduced P. australis genotypes, Eurasian-introduced P. australis would exhibit greater fitness in response to global change factors. Plasticity and plant performance to ambient and predicted levels of carbon dioxide and nitrogen pollution were investigated to understand how invasion pressure may change in North America under a realistic global change scenario. We found that the introduced Eurasian genotype expressed greater mean trait values in nearly every ecophysiological trait measured--aboveground and belowground--to elevated CO(2) and nitrogen, outperforming the native North American conspecific by a factor of two to three under every global change scenario. This response is consistent with "jack and master" phenotypic plasticity. We suggest that differences in plant nitrogen productivity, specific leaf area, belowground biomass allocation, and inherently higher relative growth rate are the plant traits that may enhance invasion of Eurasian Phragmites in North America. Given the high degree of genotypic variability within this species, and our limited number of genotypes, our results must be interpreted cautiously. Our study is the first to demonstrate the potential importance of jack-and-master phenotypic plasticity in plant invasions when facing imminent global change conditions. We suggest that jack-and-master invasive genotypes and/or species similar to ...
    Keywords Medicine ; R ; Science ; Q
    Subject code 580
    Language English
    Publishing date 2012-01-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Nitrogen enrichment alters carbon fluxes in a New England salt marsh

    Emily K. Geoghegan / Joshua S. Caplan / Francine N. Leech / Paige E. Weber / Caitlin E. Bauer / Thomas J. Mozdzer

    Ecosystem Health and Sustainability, Vol 4, Iss 11, Pp 277-

    2018  Volume 287

    Abstract: Introduction: Nitrogen enrichment of coastal salt marshes can induce feedbacks that alter ecosystem-level processes including primary production and carbon sequestration. Despite the rising interest in coastal blue carbon, the effects of chronic nutrient ...

    Abstract Introduction: Nitrogen enrichment of coastal salt marshes can induce feedbacks that alter ecosystem-level processes including primary production and carbon sequestration. Despite the rising interest in coastal blue carbon, the effects of chronic nutrient enrichment on blue carbon processes have rarely been measured in the context of experimental fertilization. Here, we examined the ecosystem-level effects of nitrate (NO3−) enrichment on the greenhouse gas dynamics of a Spartina alterniflora-dominated salt marsh. We measured CO2 and CH4 fluxes using static chambers through two growing seasons in a salt marsh that was nitrogen-enriched for 13 years and compared fluxes to those from a reference marsh. Outcomes: We found that nitrogen enrichment increased gross primary productivity (GPP) by 7.7% and increased ecosystem respiration (Reco) by 20.8%. However, nitrogen enrichment had no discernible effect on net ecosystem exchange (NEE). Taken together, these results suggest that nitrogen-induced stimulation of Reco could transform this salt marsh from a carbon sink into a source of carbon to the atmosphere. Conclusion: Our results complement prior findings of nitrogen enrichment weakening soil structure and organic matter stability in tidal salt marshes, suggesting that increased nutrient inputs have the potential to alter the carbon storage function of these ecosystems through enhanced microbial respiration of previously sequestered carbon.
    Keywords Spartina alterniflora ; blue carbon ; eutrophication ; gross primary productivity ; net ecosystem exchange ; nitrogen ; ecosystem respiration ; tidal salt marsh ; Ecology ; QH540-549.5
    Language English
    Publishing date 2018-11-01T00:00:00Z
    Publisher Taylor & Francis Group
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article: Saltmarsh plant responses to eutrophication

    Johnson, David Samuel / R. Scott Warren / Linda A. Deegan / Thomas J. Mozdzer

    Ecological applications. 2016 Dec., v. 26, no. 8

    2016  

    Abstract: In saltmarsh plant communities, bottom‐up pressure from nutrient enrichment is predicted to increase productivity, alter community structure, decrease biodiversity, and alter ecosystem functioning. Previous work supporting these predictions has been ... ...

    Abstract In saltmarsh plant communities, bottom‐up pressure from nutrient enrichment is predicted to increase productivity, alter community structure, decrease biodiversity, and alter ecosystem functioning. Previous work supporting these predictions has been based largely on short‐term, plot‐level (e.g., 1–300 m²) studies, which may miss landscape‐level phenomena that drive ecosystem‐level responses. We implemented an ecosystem‐scale, nine‐year nutrient experiment to examine how saltmarsh plants respond to simulated conditions of coastal eutrophication. Our study differed from previous saltmarsh enrichment studies in that we applied realistic concentrations of nitrate (70–100 μM NO₃ ⁻), the most common form of coastal nutrient enrichment, via tidal water at the ecosystem scale (~60,000 m² creeksheds). Our enrichments added a total of 1,700 kg N·creek⁻¹·yr⁻¹, which increased N loading 10‐fold vs. reference creeks (low‐marsh, 171 g N·m⁻²·yr⁻¹; high‐marsh, 19 g N·m⁻²·yr⁻¹). Nutrients increased the shoot mass and height of low marsh, tall Spartina alterniflora; however, declines in stem density resulted in no consistent increase in aboveground biomass. High‐marsh plants S. patens and stunted S. alterniflora did not respond consistently to enrichment. Nutrient enrichment did not shift community structure, contrary to the prediction of nutrient‐driven dominance of S. alterniflora and Distichlis spicata over S. patens. Our mild responses may differ from the results of previous studies for a number of reasons. First, the limited response of the high marsh may be explained by loading rates orders of magnitude lower than previous work. Low loading rates in the high marsh reflect infrequent inundation, arguing that inundation patterns must be considered when predicting responses to estuarine eutrophication. Additionally, we applied nitrate instead of the typically used ammonium, which is energetically favored over nitrate for plant uptake. Thus, the form of nitrogen enrichment used, not just N‐load, may be important in predicting plant responses. Overall, our results suggest that when coastal eutrophication is dominated by nitrate and delivered via flooding tidal water, aboveground saltmarsh plant responses may be limited despite moderate‐to‐high water‐column N concentrations. Furthermore, we argue that the methodological limitations of nutrient studies must be considered when using results to inform management decisions about wetlands.
    Keywords Distichlis spicata ; Spartina alterniflora ; aboveground biomass ; ammonium ; biodiversity ; community structure ; ecosystems ; estuaries ; eutrophication ; nitrates ; nitrogen ; nitrogen content ; nutrients ; plant communities ; plant response ; pollution load ; prediction ; salt marsh plants ; salt marshes ; streams
    Language English
    Dates of publication 2016-12
    Size p. 2647-2659.
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 1074505-1
    ISSN 1939-5582 ; 1051-0761
    ISSN (online) 1939-5582
    ISSN 1051-0761
    DOI 10.1002/eap.1402
    Database NAL-Catalogue (AGRICOLA)

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  9. Article: Limits to soil carbon stability; Deep, ancient soil carbon decomposition stimulated by new labile organic inputs

    Bernal, Blanca / Bruce A. Hungate / Duncan C. McKinley / J. Patrick Megonigal / Paul M. White / Thomas J. Mozdzer

    Elsevier Ltd Soil biology & biochemistry. 2016 July, v. 98

    2016  

    Abstract: Carbon (C) buried deep in soil (below 1 m) is often hundreds to thousands of years old, though the stability and sensitivity of this deep C to environmental change are not well understood. We examined the C dynamics in three soil horizons and their ... ...

    Abstract Carbon (C) buried deep in soil (below 1 m) is often hundreds to thousands of years old, though the stability and sensitivity of this deep C to environmental change are not well understood. We examined the C dynamics in three soil horizons and their responses to changes in substrate availability in a coarse-textured sandy spodosol (0.0–0.1, 1.0–1.3, and 2.7–3.0 m deep). Substrate additions were intended to mimic an increase in root exudates and available inorganic nitrogen (N) that would follow an increase of belowground biomass at depth, as previously found in a long-term CO2 enrichment experiment at this site. We incubated these soils for 60 days with glucose, alanine, and leaf litter, crossed with an inorganic N amendment equivalent to three times ambient concentrations. The organic substrates were isotopically labeled (13C), allowing us to determine the source of mineralized C and assess the priming effect. Enzyme activity increased as much as 13 times in the two deeper horizons (1.0–1.3, and 2.7–3.0 m) after the addition of the organic substrates, even though the deepest horizon had microbial biomass and microbial phospholipid fatty acids below the level of detection before the experiment. The deepest horizon (2.7–3.0 m) yielded the largest priming response under alanine, indicating that microorganisms in these soil horizons can become active in response to input of organic substrates. Inorganic N amendments significantly decreased the priming effect, suggesting that decomposition may not be N limited. However, alanine (organic N) yielded the highest priming effect at every soil depth, indicating the importance of differentiating effect of organic and inorganic N on decomposition. Distinct priming effects with depth suggest that portions of the soil profile can respond differently to organic inputs. Our findings indicate that the deep soil C pools might be more vulnerable to environmental or anthropogenic change than previously thought, potentially influencing net CO2 exchange estimates between the land and the atmosphere.
    Keywords alanine ; anthropogenic activities ; belowground biomass ; carbon ; carbon dioxide ; carbon sinks ; degradation ; enzyme activity ; glucose ; isotope labeling ; microbial biomass ; mineralization ; nitrogen ; phospholipid fatty acids ; plant litter ; root exudates ; soil amendments ; soil biology ; soil depth ; soil horizons ; soil microorganisms ; soil profiles ; Spodosols
    Language English
    Dates of publication 2016-07
    Size p. 85-94.
    Publishing place Elsevier Ltd
    Document type Article
    ZDB-ID 280810-9
    ISSN 0038-0717
    ISSN 0038-0717
    DOI 10.1016/j.soilbio.2016.04.007
    Database NAL-Catalogue (AGRICOLA)

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  10. Article: Complex invader-ecosystem interactions and seasonality mediate the impact of non-native Phragmites on CH4 emissions

    Mueller, Peter / J. Adam Langley / J. Patrick Megonigal / Justin E. Meschter / Kai Jensen / Rachel N. Hager / Thomas J. Mozdzer

    Biological invasions. 2016 Sept., v. 18, no. 9

    2016  

    Abstract: Invasive plants can influence ecosystem processes such as greenhouse gas (GHG) emissions from wetland systems directly through plant-mediated transfer of GHGs to the atmosphere or through indirect modification of the environment. However, patterns of ... ...

    Abstract Invasive plants can influence ecosystem processes such as greenhouse gas (GHG) emissions from wetland systems directly through plant-mediated transfer of GHGs to the atmosphere or through indirect modification of the environment. However, patterns of plant invasion often co-vary with other environmental gradients, so attributing ecosystem effects to invasion can be difficult in observational studies. Here, we assessed the impact of Phragmites australis invasion into native shortgrass communities on methane (CH₄) emissions by conducting field measurements of CH₄ emissions along transects of invasion by Phragmites in two neighboring brackish marsh sites and compared these findings to those from a field-based mesocosm experiment. We found remarkable differences in CH₄ emissions and the influence of Phragmites on CH₄ emissions between the two neighboring marsh sites. While Phragmites consistently increased CH₄ emissions dramatically by 10.4 ± 3.7 µmol m⁻² min⁻¹ (mean ± SE) in our high-porewater CH₄ site, increases in CH₄ emissions were much smaller (1.4 ± 0.5 µmol m⁻² min⁻¹) and rarely significant in our low-porewater CH₄ site. While CH₄ emissions in Phragmites-invaded zones of both marsh sites increased significantly, the presence of Phragmites did not alter emissions in a complementary mesocosm experiment. Seasonality and changes in temperature and light availability caused contrasting responses of CH₄ emissions from Phragmites- versus native zones. Our data suggest that Phragmites-mediated CH₄ emissions are particularly profound in soils with innately high rates of CH₄ production. We demonstrate that the effects of invasive species on ecosystem processes such as GHG emissions may be predictable qualitatively but highly variable quantitatively. Therefore, generalizations cannot be made with respect to invader-ecosystem processes, as interactions between the invader and local abiotic conditions that vary both spatially and temporally on the order of meters and hours, respectively, can have a stronger impact on GHG emissions than the invader itself.
    Keywords ecological invasion ; ecosystems ; greenhouse gas emissions ; greenhouse gases ; invasive species ; marshes ; methane ; methane production ; observational studies ; Phragmites australis ; plants (botany) ; soil ; temperature
    Language English
    Dates of publication 2016-09
    Size p. 2635-2647.
    Publishing place Springer International Publishing
    Document type Article
    ZDB-ID 1438729-3
    ISSN 1573-1464 ; 1387-3547
    ISSN (online) 1573-1464
    ISSN 1387-3547
    DOI 10.1007/s10530-016-1093-6
    Database NAL-Catalogue (AGRICOLA)

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