Deep rooting and global change facilitate spread of invasive grass

Mozdzer, Thomas J.; Langley, J. Adam; Mueller, Peter; Megonigal, J. Patrick

doi:10.1007/s10530-016-1156-8

Cited by 40 publications

(37 citation statements)

References 57 publications

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“…These data support biogeochemical feedbacks proposed by Mozdzer et al . (), in which the introduction of deep‐rooting species (e.g., P. australis ) into wetlands causes structural changes in root depth distribution that can lead to an increase in SOM mineralization relative to native plants (Fig. ).…”

Section: Discussionmentioning

confidence: 97%

“…The ability of P. australis to engineer ecosystems relies on the same morphological traits and phenology that allow it to be a successful invader. These traits include an extensive and deep root system (Burdick et al ., ; Windham, ; Rooth et al ., ; Moore et al ., ; Mozdzer et al ., ), high photosynthetic rates (Mozdzer & Zieman, ; Mozdzer et al ., ), the ability to reproduce vegetatively through clonal integration (Amsberry et al ., ; Burdick et al ., ), high aboveground biomass production and litter accumulation in the soil surface (Meyerson et al ., ; Brix et al ., ; Findlay et al ., ; Rooth et al ., ), and efficient aeration of the rhizosphere through radial oxygen loss and convective gas flow (Brix et al ., ; Armstrong et al ., , ; Windham & Lathrop, ; Engloner, ; Tulbure et al ., ; Kiviat, ). All these features have a direct effect on cycling and accumulation of soil organic matter (SOM), nutrient cycling, and water flux, as well as other compounds such as micronutrients, phytotoxins, and heavy metals (Romero et al ., ; Ehrenfeld, ; Windham et al ., ; Engloner, ; Hazelton et al ., ).…”

Section: Introductionmentioning

confidence: 99%

“…P. australis litter accumulation also facilitates the deposition of organic and mineral matter from incoming tides, potentially contributing to vertical accretion (Rooth et al ., ). Belowground, P. australis develops an extensive network of roots and rhizomes that extend to depths far beyond those of the native community (Moore et al ., ; Meschter, ; Mozdzer et al ., ), which typically concentrate in the top ~30 cm of the soil (Curtis et al ., ; Windham & Lathrop, ; Windham, ; Armstrong et al ., ). The balance between root growth and decay determines autochthonous soil C sequestration, a process that helps coastal marshes to accrete peat and keep up with sea level rise (Langley et al ., ; Deegan et al ., ; Kirwan & Megonigal, ).…”

Section: Introductionmentioning

confidence: 99%

“…The introduction of a deep‐rooting plant species in shallow‐rooted ecosystems, like P. australis into wetlands, has the potential to alter biogeochemical cycles deep within the soil profile (Mozdzer et al ., ). P. australis may increase soil C outputs by inducing SOM decomposition through a ‘priming effect’, that is, the increase in SOM mineralization that follows the addition of fresh organic compounds (Blagodatskaya et al ., ; Cheng, ; Fischer et al ., ; Kuzyakov, ).…”

Section: Introductionmentioning

confidence: 99%

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An invasive wetland grass primes deep soil carbon pools

Bernal

Megonigal

Mozdzer

2016

Global Change Biology

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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 CO produced came from plant tissue mineralization in invasive and native communities; the rest of the CO was produced from SOM mineralization (priming). Under P. australis, 35% of the CO was produced from deep SOM priming and 9% from surface SOM. In the native community, 9% was produced from deep SOM priming and 44% from surface SOM. SOM priming in the native community was proportional to belowground biomass, while P. australis showed much higher priming with less belowground biomass. If P. australis deep rooting favors the decomposition of deep-buried SOM accumulated under native vegetation, P. australis invasion into a wetland could fundamentally change SOM dynamics and lead to the loss of the C pool that was previously sequestered at depth under the native vegetation, thereby altering the function of a wetland as a long-term C sink.

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Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An invasive wetland grass primes deep soil carbon pools

Bernal

Megonigal

Mozdzer

2016

Global Change Biology

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“…stem height and leaf area). In addition, P. australis invasions are not likely to be limited by N availability once established given the lineage's ability to root deeply (Mozdzer, Langley, Mueller, & Megonigal, 2016) and increase N availability by priming the microbial decomposition of organic matter (Bernal, Megonigal, & Mozdzer, 2017).…”

Section: Responses To Nitrogenmentioning

confidence: 99%

Complementary responses of morphology and physiology enhance the stand‐scale production of a model invasive species under elevated CO₂ and nitrogen

Mozdzer

Caplan

2018

Functional Ecology

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Elevated atmospheric carbon dioxide (eCO2) concentrations and nitrogen (N) enrichment are known to enhance plant productivity and invasion. However, the implications of their interactive effects for plant productivity are not well understood, especially at the stand scale, presumably because morphological and physiological responses to these global change factors are rarely studied together in the field or assessed at the stand level. We first determined how leaf‐level morphological and physiological traits responded to factorial combinations of ambient and elevated CO2 and N. We collected trait data from the model invasive species Phragmites australis (common reed) that were measured over 3 years in a long‐term global change field experiment. We then combined the trait data and additional descriptions of P. australis canopies in a simulation model of carbon assimilation to determine how morphology and physiology contribute to P. australis’ stand‐scale productivity. At the leaf level, we found that light‐saturated rates of photosynthesis were strongly stimulated by eCO2 (37%) and that this effect was enhanced by increasing salinity. N had a smaller effect (17% stimulation) on physiological responses than eCO2, but leaf morphological traits responded primarily to N; plant height increased by 27% and leaf area increased by 47%. Stand‐scale simulations demonstrated that that morphological and physiological adjustments induced approximately additive responses when P. australis experienced both eCO2 and N enrichment. The simulations also indicated that morphological changes (which were primarily associated with canopy size) influenced stand‐scale carbon assimilation more than physiological changes. Moreover, 97% of the N response was due to changes in morphology, whereas 62% of the eCO2 response was caused by physiological shifts. Our analysis indicates that morphological and physiological trait responses to elevated CO2 and nitrogen are likely to enhance the productivity of P. australis in complementary ways, potentially accelerating its invasion in North America. Furthermore, our data suggest that changes in morphological traits may have a greater influence on carbon gain than leaf‐level physiology under near‐future environmental conditions. Our study also highlights the importance of accounting for both morphological and physiological responses when attempting to infer global change responses from leaf‐level data. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13106/suppinfo is available for this article.

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Vegetation zones as indicators of denitrification potential in salt marshes

Ooi

Barry

Lawrence

et al. 2022

Ecological Applications

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Salt marsh vegetation zones shift in response to large-scale environmental changes such as sea-level rise (SLR) and restoration activities, but it is unclear if they are good indicators of soil nitrogen removal. Our goal was to characterize the relationship between denitrification potential and salt marsh vegetation zones in tidally restored and tidally unrestricted coastal marshes, and to use vegetation zones to extrapolate how SLR may influence high marsh denitrification at the landscape scale. We conducted denitrification enzyme activity assays on sediment collected from three vegetation zones expected to shift in distribution due to SLR and tidal flow restoration across 20 salt marshes in Connecticut, USA (n = 60 sampling plots) during the summer of 2017. We found lower denitrification potential in short-form Spartina alterniflora zones (mean, 95% CI: 4, 3-6 mg N h À1 m À2 ) than in S. patens (25, 15-36 mg N h À1 m À2 ) and Phragmites australis (56, 16-96 mg N h À1 m À2 ) zones. Vegetation zone was the single best predictor and explained 52% of the variation in denitrification potential; incorporating restoration status and soil characteristics (soil salinity, moisture, and ammonium) did not improve model fit.Because denitrification potential did not differ between tidally restored and unrestricted marshes, we suggest landscape-scale changes in denitrification after tidal restoration are likely to be associated with shifts in vegetation, rather than differences driven by restoration status. Sea-level-rise-induced hydrologic changes are widely observed to shift high marsh dominated by S. patens to short-form S. alterniflora. To explore the implications of this shift in dominant high marsh vegetation, we paired our measured mean denitrification potential rates with projections of high marsh loss from SLR. We found that, under low and medium SLR scenarios, predicted losses of denitrification potential due to replacement of S. patens by short-form S. alterniflora were substantially larger than losses due to reduced high marsh land area alone. Our results suggest that changes in vegetation zones can serve as

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Deep rooting and global change facilitate spread of invasive grass

Cited by 40 publications

References 57 publications

An invasive wetland grass primes deep soil carbon pools

An invasive wetland grass primes deep soil carbon pools

Complementary responses of morphology and physiology enhance the stand‐scale production of a model invasive species under elevated CO₂ and nitrogen

Vegetation zones as indicators of denitrification potential in salt marshes

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Deep rooting and global change facilitate spread of invasive grass

Cited by 40 publications

References 57 publications

An invasive wetland grass primes deep soil carbon pools

An invasive wetland grass primes deep soil carbon pools

Complementary responses of morphology and physiology enhance the stand‐scale production of a model invasive species under elevated CO2 and nitrogen

Vegetation zones as indicators of denitrification potential in salt marshes

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Product

Resources

About

Complementary responses of morphology and physiology enhance the stand‐scale production of a model invasive species under elevated CO₂ and nitrogen