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1. Identifying high-impact invasive plants likely to shift into northern New England with climate change

   https://doi.org/10.1017/inp.2021.10  

   Coville, William; Griffin, Bridget J.; Bradley, Bethany A. (June 2021, Invasive Plant Science and Management)

   null (Ed.)

   Abstract Invasive plants are expanding their ranges due to climate change, creating new challenges for invasive species management. Early detection and rapid response could address some nascent invasions, but limited resources make it impossible to monitor for every range-shifting species. Here, we aimed to create a more focused watch list by evaluating the impacts of 87 plant species projected to shift into northern New England (the states of Maine, New Hampshire, and/or Vermont). We used the Environmental Impact Classification for Alien Taxa (EICAT) protocol to evaluate all ecological impacts reported in the scientific literature, scoring ecological impacts from 1 (minimal concern) to 4 (major) depending on the level of reported impact. For each species, we also recorded any reported impacts on socioeconomic systems (agriculture, human health, or economics) as “present.” We found 24 range-shifting species with impacts on ecological communities, of which 22 have reported impacts in ecosystems common to northern New England. Almost all of these species also had impacts on socioeconomic systems and were available for purchase at ornamental plant retailers or online. Thus, these species can be considered high risk to northern New England with climate change based on their large negative impacts and potential to arrive quickly with deliberate human introduction. Our study demonstrates the use of impact assessments for creating targeted priority lists for invasive species monitoring and management. 

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2. Allelopathy is pervasive in invasive plants

   https://doi.org/10.1007/s10530-020-02383-6  

   Kalisz, Susan; Kivlin, Stephanie N.; Bialic-Murphy, Lalasia (February 2021, Biological Invasions)

   Abstract Invasive species utilize a wide array of trait strategies to establish in novel ecosystems. Among these traits is the capacity to produce allelopathic compounds that can directly inhibit neighboring native plants or indirectly suppress native plants via disruption of beneficial belowground microbial mutualisms, or altered soil resources. Despite the well-known prevalence of allelopathy among plant taxa, the pervasiveness of allelopathy among invasive plants is unknown. Here we demonstrate that the majority of the 524 invasive plant species in our database produce allelochemicals with the potential to negatively affect native plant performance. Moreover, allelopathy is widespread across the plant phylogeny, suggesting that allelopathy could have a large impact on native species across the globe. Allelopathic impacts of invasive species are often thought to be present in only a few plant clades (e.g., Brassicaceae). Yet our analysis shows that allelopathy is present in 72% of the 113 plant families surveyed, suggesting that this ubiquitous mechanism of invasion deserves more attention as invasion rates increase across the globe. 

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3. Biological Interactions and Disturbance in Arid Ecosystems: Examples From the Great Basin, Mojave, and Northern Chihuahuan Deserts

   Lee, Steven (July 2024, ProQuest)

   In an era where human influence pervades every corner of the natural world, improving our understanding the how ecosystems are structured and function has never been more critical. Dryland ecosystems, occupying over 40% of the plant’s land surface area, represent the largest terrestrial biome on earth. Drylands are particularly vulnerable to global change pressures such as rising temperatures, altered precipitation regimes, and the spread of invasive species. The Earth's climate is changing rapidly, exacerbating these pressures and threatening the productivity, biodiversity, and function of dryland ecosystems. The interactions between these shifting pressures and disturbances, both natural and anthropogenic, add layers of complexity that challenge our understanding of these ecosystems. In my dissertation, I used a combination of observational and experimental studies to investigate the impacts of disturbances on vegetation within dryland ecosystems, focusing particularly on the interactions between climate and biological factors known to influence the structure and function of plants. A rainfall manipulation and mechanical disturbance experiment repeated in three climatically distinct North America dryland ecosystems revealed complex, site-specific responses of dominant shrubs to environmental stressors. Findings indicated that individual traits, such as plant size, significantly influence sensitivity to climate changes, highlighting the need for localized management strategies. A study assessing the trophic impacts from a native twig girdling beetle on the above ground biomass of honey mesquite (Prosopis glandulosa) found significant year-to-year variability in beetle activity, with notable reductions in mesquite biomass due to girdling that exceeded estimates for annual net primary production for some years. A study assessing the influence of fire on biodiversity of soil seed bank across the Mojave found increased diversity in burned areas, but highlights the dominance of invasive species, ultimately leading to biodiversity loss and community homogenization. These findings underscore the significant impact of invasive species and the necessity of management practices to mitigate their spread. Collectively, this dissertation provides a nuanced understanding of how natural and novel disturbance regimes affect dryland ecosystems. The differential responses among species and ecosystems suggest that effective management strategies must consider local ecological contexts to preserve productivity and biodiversity amidst rapidly changing global pressures. 

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4. A Quantitative Classification of the Geography of Non‐Native Flora in the United States

   https://doi.org/10.1111/geb.70041  

   Bradley, Bethany A; Evans, Annette E; Sofaer, Helen R; Vilà, Montserrat; Barnett, David T; Beaury, Evelyn M; Blumenthal, Dana M; Corbin, Jeffrey D; Dukes, Jeffrey S; Early, Regan; et al (April 2025, Global Ecology and Biogeography)

   ABSTRACT AimNon‐native plants have the potential to harm ecosystems. Harm is classically related to their distribution and abundance, but this geographical information is often unknown. Here, we assess geographical commonness as a potential indicator of invasive status for non‐native flora in the United States. Geographical commonness could inform invasion risk assessments across species and ecoregions. LocationConterminous United States. Time PeriodThrough 2022. Major Taxa StudiedPlants. MethodsWe compiled and standardised occurrence and abundance data from 14 spatial datasets and used this information to categorise non‐native species as uncommon or common based on three dimensions of commonness: area of occupancy, habitat breadth and local abundance. To assess consistency in existing categorizations, we compared commonness to invasive status in the United States. We identified species with higher‐than‐expected abundance relative to their occupancy, habitat breadth or residence time. We calculated non‐native plant richness within United States ecoregions and estimated unreported species based on rarefaction/extrapolation curves. ResultsThis comprehensive database identified 1874 non‐native plant species recorded in 4,844,963 locations. Of these, 1221 species were locally abundant (> 10% cover) in 797,759 unique locations. One thousand one hundred one non‐native species (59%) achieved at least one dimension of commonness, including 565 species that achieved all three. Species with longer residence times tended to meet more dimensions of commonness. We identified 132 species with higher‐than‐expected abundance. Ecoregions in the central United States have the largest estimated numbers of unreported, abundant non‐native plants. Main ConclusionsA high proportion of non‐native species have become common in the United States. However, existing categorizations of invasive species are not always consistent with species' abundance and distribution, even after considering residence time. Considering geographical commonness and higher‐than‐expected abundance revealed in this new dataset could support more consistent and proactive identification of invasive plants and lead to more efficient management practices. 

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5. Optimizing control of a freshwater invader in time and space

   https://doi.org/10.1002/eap.70026  

   Diallo, Jessica O; Converse, Sarah J; Chmiel, Matthew; Stites, Andrew J; Olden, Julian D (April 2025, Ecological Applications)

   Abstract The global spread of invasive species in aquatic ecosystems has prompted population control efforts to mitigate negative impacts on native species and ecosystem functions. Removal programs that optimally allocate removal effort across space and time offer promise for improving invader suppression or eradication, especially given the limited resources available to these programs. However, science‐based guidance to inform such programs remains limited. This study leverages two intensive fish removal programs for nonnative green sunfish (Lepomis cyanellus) in intermittent streams of the Bill Williams River basin in Arizona, USA, to explore alternative management strategies involving variable allocation of removal effort in time and space and compare static versus dynamic decision rules. We used Bayesian hierarchical modeling to estimate demographic parameters using existing removal data, with evidence that both removal programs led to at least a 0.39 probability of eradication. Simulated alternative management strategies revealed that population suppression, but not eradication, could be achieved with reduced effort and that dynamic management practices that respond to species abundance in real time can improve the efficiency of removal efforts. High removal frequency and program duration, including continued monitoring after zero fish were captured, contributed to successful population control. With management efforts struggling to keep pace with the rising spread and impacts of invasive species, this research demonstrates the utility of quantitative removal models to help improve invasive removal programs and robustly evaluate the success of population suppression and eradication. 

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