Surveying managers to inform a regionally relevant invasive Phragmites australis control research program

Rohal, Christine B.; Kettenring, Karin M.; Sims, Katharine R. E.; Hazelton, Eric L. G.; Ma, Zhao

doi:10.1016/j.jenvman.2017.10.049

Cited by 31 publications

(50 citation statements)

References 70 publications

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“…While some studies in tidal ecosystems have found diverse native seed banks under Phragmites (e.g., Hazelton, Downard, Kettenring, McCormick, & Whigham, ), the composition and densities may not match noninvaded areas and may be highly variable across sites. The reference wetlands in this study were dominated by three bulrush species that are important habitat and provide energy‐rich seed forage for migratory birds (Downard et al, ), an ecosystem function that is a main goal of local restoration efforts (Rohal et al, ). The assembling plant communities in our treatment plots, however, had low cover of bulrush species (<10% cover in most plots), which indicates that this goal may not be met without further restoration action.…”

Section: Discussionmentioning

confidence: 99%

“…Dominant native vegetation includes Typha domingensis / T. latifolia (cattails), Bolboschoenus maritimus (alkali bulrush), Schoenoplectus acutus (hardstem bulrush), S. americanus (common threesquare), and Distichlis spicata (saltgrass; Downard, Frank, Perkins, Kettenring, & Larese‐Casanova, ). Phragmites began to invade Great Salt Lake wetlands after floods in the 1980s (Kettenring et al, ; Rohal et al, ) and now occupies more than 93 km 2 in the region (Long et al, ).…”

Section: Methodsmentioning

confidence: 99%

“…We evaluated six Phragmites management treatments: (a) summer glyphosate spray, followed by a winter mow (“SGWM”); (b) summer imazapyr spray, followed by a winter mow (“SIWM”); (c) fall glyphosate spray, followed by a winter mow (“FGWM”); (d) summer mow, followed by a fall glyphosate spray (“SMFG”); (e) summer mow then cover plots with heavy‐duty black plastic (i.e., a solarization treatment; “SMBP”); and (f) untreated control (“CONT”). These treatments were chosen based on manager interest and feasibility after lengthy interviews and a formal survey (Rohal et al, ). We randomly assigned each treatment to a plot ( n = 30) at five of six sites, such that all six treatments were replicated five times in a randomized, balanced, incomplete block design (Figure ).…”

Section: Methodsmentioning

confidence: 99%

“…In the first ordination, we sought to visualize plant community trajectories over years 2014, 2015, and 2016 (i.e., when reference data were collected) in herbicide treatment plots relative to the untreated control and the target reference communities. In the second ordination, we sought to describe the influences of environmental variables on assembling plant communities, and the response of multiple plant guilds that are important to managers within the herbicide treated plots in 2016, the final monitoring year (Rohal et al, ). Plant guild metrics such as native perennials, graminoids, and forb cover were calculated by adding the cover of plants within each specific guild within a quadrat and then averaging quadrat cover values across plots.…”

Section: Methodsmentioning

confidence: 99%

“…Others have sought nonchemical Phragmites management options to minimize environmental impacts, like solarization (heating soil to temperatures lethal to Phragmites rhizomes), but these strategies have not been rigorously evaluated. Managers have expressed uncertainties about the most effective type of herbicide, as well as the best timing of herbicide application for both Phragmites removal and native plant recovery (Rohal, Kettenring, Sims, Hazelton, & Ma, ). Imazapyr was more effective than glyphosate at Phragmites removal in some studies (Derr, ; Mozdzer, Hutto, Clarke, & Field, ), but there are questions about its long‐term impact on native plant recovery due to its persistence (up to 4 years) in the soil, and ability to be adsorbed by plant roots (Hazelton et al, ; Tu, Hurd, & Randall, ).…”

Section: Introductionmentioning

confidence: 99%

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Invasive Phragmites australis management outcomes and native plant recovery are context dependent

Rohal

Cranney

Hazelton

et al. 2019

Ecology and Evolution

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The outcomes of invasive plant removal efforts are influenced by management decisions, but are also contingent on the uncontrolled spatial and temporal context of management areas. Phragmites australis is an aggressive invader that is intensively managed in wetlands across North America. Treatment options have been understudied, and the ecological contingencies of management outcomes are poorly understood. We implemented a 5‐year, multi‐site experiment to evaluate six Phragmites management treatments that varied timing (summer or fall) and types of herbicide (glyphosate or imazapyr) along with mowing, plus a nonherbicide solarization treatment. We evaluated treatments for their influence on Phragmites and native plant cover and Phragmites inflorescence production. We assessed plant community trajectories and outcomes in the context of environmental factors. The summer mow, fall glyphosate spray treatment resulted in low Phragmites cover, high inflorescence reduction, and provided the best conditions for native plant recruitment. However, returning plant communities did not resemble reference sites, which were dominated by ecologically important perennial graminoids. Native plant recovery following initial Phragmites treatments was likely limited by the dense litter that resulted from mowing. After 5 years, Phragmites mortality and native plant recovery were highly variable across sites as driven by hydrology. Plots with higher soil moisture had greater reduction in Phragmites cover and more robust recruitment of natives compared with low moisture plots. This moisture effect may limit management options in semiarid regions vulnerable to water scarcity. We demonstrate the importance of replicating invasive species management experiments across sites so the contingencies of successes and failures can be better understood.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Invasive Phragmites australis management outcomes and native plant recovery are context dependent

Rohal

Cranney

Hazelton

et al. 2019

Ecology and Evolution

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Tipping the balance: The role of seed density, abiotic filters, and priority effects in seed‐based wetland restoration

Tarsa

Holdaway

Kettenring

2022

Ecological Applications

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Sowing native seeds is a common approach to reintroduce native plants to degraded systems. However, this method is often overlooked in wetland restoration despite the immense global loss of diverse native wetland vegetation.Developing guiding principles for seed-based wetland restoration is critical to maximize native plant recovery, particularly in previously invaded wetlands. Doing so requires a comprehensive understanding of how restoration manipulations, and their interactions, influence wetland plant community assembly. With a focus on the invader Phragmites australis, we established a series of mesocosm experiments to assess how native sowing density, invader propagule pressure, abiotic filters (water and nutrients), and native sowing timing (i.e., priority effects) interact to influence plant community cover and biomass in wetland habitats. Increasing the density of native seeds yielded higher native cover and biomass, but P. australis suppression with increasing sowing densities was minimal. Rather, community outcomes were largely driven by invader propagule pressure: P. australis densities of ≤500 seeds/m 2 maintained high native cover and biomass. Low-water conditions increased the susceptibility of P. australis to dominance by native competitors. Early sowing of native seeds showed a large and significant benefit to native cover and biomass, regardless of native sowing density, suggesting that priority effects can be an effective restoration manipulation to enhance native plant establishment. Given the urgent wetland restoration need combined with the limited studies on seed-based wetland restoration, these findings provide guidance on restoration manipulations that are grounded in ecological theory to improve seed-based wetland restoration outcomes.

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Landscape and site factors drive invasive Phragmites management and native plant recovery across Chesapeake Bay wetlands

et al. 2023

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Successful invasive plant management-where invaders are sufficiently reduced and diverse native plant communities recover-remains an elusive goal for land managers. The site-and landscape-scale drivers of variable management outcomes and vegetation recovery are poorly understood due to a lack of rigorous experiments that characterize longer term vegetation trends across contexts. We present the results of a five-year experiment across eight subestuaries of Chesapeake Bay, representing a gradient of watersheds with differing dominant land-use types and anthropogenic impacts, to evaluate invasive and native plant response to herbicide management. The focal invader, Phragmites australis (common reed), is one of the most aggressive and pervasive invasive plants in North American wetlands. We found that with multiyear herbicide treatments, it was possible to greatly reduce Phragmites across an array of subestuaries while increasing the cover and quality of native plant communities. Yet, by the end of the study, plant community composition in all Phragmites-managed sites remained distinct from, even if composition was shifting toward, reference sites. There was also large inter-site variation in the vegetation responses related to site environmental conditions and subestuary vegetation conditions. We uncovered specific aspects of the surrounding landscape that were linked to improved vegetation recovery-the species richness and conservation value of nearby wetlands. Results from this five-year experiment conducted at multiple sites in Chesapeake Bay inform what is possible for management, particularly in more degraded landscapes and sites where setting realistic expectations and pragmatic goals will be essential. Assessing environmental and vegetation conditions of the site and surrounding landscape prior to commencing invasive species management is critical to predict the time and effort required to achieve restoration goals.

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Surveying managers to inform a regionally relevant invasive Phragmites australis control research program

Cited by 31 publications

References 70 publications

Invasive Phragmites australis management outcomes and native plant recovery are context dependent

Invasive Phragmites australis management outcomes and native plant recovery are context dependent

Tipping the balance: The role of seed density, abiotic filters, and priority effects in seed‐based wetland restoration

Landscape and site factors drive invasive Phragmites management and native plant recovery across Chesapeake Bay wetlands

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