One way that climate change is projected to affect invasive plant management is by shifting the ranges of invasive plants. In some regions, hundreds of new, potentially invasive species could establish in coming decades. These species are prime candidates for early detection and rapid response. However, with limited resources, it is unlikely that invasive plant managers will be able to monitor and treat this large number of novel species. Determining which species are likely to have the greatest impacts could inform further risk assessment and mitigate the greatest amount of potential damage. Here, we used the Environmental Impact Classification for Alien Taxa (EICAT) protocol to evaluate the potential impacts of 104 invasive plant species that are projected to establish in Delaware, Kentucky, Maryland, New Jersey, Ohio, Pennsylvania, Virginia, and/or West Virginia by midcentury with climate change. These species were identified using the Invasive Range Expanders Listing Tool to predict which invasive species are likely to shift their ranges into the target states by midcentury. We used Web of Science to search for studies on each species involving impacts to ecological or socioeconomic sectors. We scored ecological impacts on a scale of 1 (“minimal concern”) to 4 (“major concern”) and socioeconomic impacts as present or not present. We evaluated 674 papers and categorized the species into these categories: 32 high-impact species, 20 moderate-impact species, and 13 minor- or minimal-impact species. Two of the 32 high-impact species (panic veldtgrass [Ehrharta erecta Lam.] and Athel tamarisk [Tamarix aphylla (L.) Karst.]) pose a risk to all eight mid-Atlantic states. There were also 46 species that pose a risk to socioeconomic sectors, including agriculture, the economy, and human health. Twenty-four species were listed as data deficient (no data could be found on them). This study provides a comprehensive review of reported impacts of range-shifting invasive plants in the mid-Atlantic.

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.

Invasive alien plant species (IAPS) are spreading into protected areas worldwide; however, knowledge of these invasions and their impacts in Nepal’s protected areas is poor. Here, the spatial distribution pattern of IAPS in Bardia National Park (BNP), Nepal, was analysed using roadside surveys and grid sampling. The impacts of the most abundant IAPS, Lantana camara, on plant communities were analysed by comparing 60 pairs of non-invaded and invaded quadrats. Twelve IAPS, including two of the most prolific species globally, L. camara and Chromolaena odorata, were recorded from BNP. The Karnali floodplain in the south-western region of the park, a prime habitat of one-horned rhinoceros, was highly invaded by the IAPS. Tree canopy and distance to road, river and settlement were the major factors affecting IAPS occurrence. Lantana camara modified plant community structure and significantly reduced plant species richness and diversity; species richness of native plants was reduced to less than half in invaded plots. Plant invasions and impacts on native plant diversity have been increasing in BNP. We recommend management interventions involving immediate eradication of C. odorata and other species with single satellite populations and control measures for other widespread species such as L. camara and Ageratum houstonianum.

Governments and conservation organizations worldwide are motivated to manage invasive species due to quantified and perceived negative ecological and economic impacts invasive species impose. Thus, determining which species cause significant negative impacts, as well as clear articulation of those impacts, is critical to meet conservation priorities. This process of determining which species warrant management can be straightforward when there are clear negative impacts, such as dramatic reductions in native diversity. However, the majority of changes to ecosystem pools and fluxes cannot be readily categorized as ecologically negative or positive (e.g., lower soil pH). Additionally, diverse stakeholders may not all agree on impacts as negative. This complexity challenges our ability to simply and uniformly determine which species cause negative impact, and thus which species merit management, especially as we expand invader impacts to encompass a more holistic ecosystem perspective beyond biodiversity and consider stakeholder perspectives and priorities. Thus, we suggest impact be evaluated in a context that is dictated by governing policies or conservation/land management missions with the support of scientists. In other words, within each jurisdiction, populations are identified as causing negative impact based on the hierarchical governing policies and mission of that parcel. Framing negative impact in a management context has the advantages of (1) easily scaling from individual landscapes to geopolitical states; (2) better representing how managers practice, (3) reflecting invasive species as spatially contextual, not universal, and (4) allowing for flexibility with dynamic ecosystems undergoing global change. We hope that framing negative impact in an applied context aids management prioritization and achieving conservation goals.

Nonindigenous plant species (NIS) can affect individuals, communities, and ecosystems through numerous direct and indirect mechanisms. To synthesize the current understanding of how NIS cause impacts, we reviewed experimental research from the past decade. We found alteration of the microenvironment, such as incident light and air and soil temperature, was much more often a mechanism underlying NIS impacts than competition for soil water and nutrients. NIS litter frequently caused the alteration of microenvironments, and litter effects were often of greater consequence than the effects of live NIS plants. Results supported altered soil microbial communities and mycorrhizal associations as mechanisms underlying NIS impacts on native plant growth, community structure, and nutrient cycling. Impacts often could not be attributed to a single mechanism, highlighting the need for multi-factor studies that identify and distinguish between multiple, concurrently operating mechanisms. Overall, our synthesis indicates that effective management will require attention to legacy effects of NIS, that removing live NIS may not ameliorate impacts, and that removal of dead NIS biomass may be necessary for native species' survival. Furthermore, rehabilitating soil microbial and mycorrhizal communities may be crucial for successful post-NIS management revegetation.

Little is known about the impacts of intensive shellfish farming on intertidal ecosystems. To assess such impacts, several indices of ecosystem structure and select geochemical characteristics were contrasted among three intertidal regions, which represented a gradient of shellfish farming activities, namely (1) no active aquaculture, (2) actively farmed for three years and (3) actively farmed for five years. All three intertidal regions were located in Baynes Sound (British Columbia, Canada) and were geographically similar. Among the three beaches, species richness, community composition, bivalve abundance, biomass, distribution, and composition and surficial sediment per cent organic matter (carbon) and silt were compared. The intertidal regions that had been used for farming for three and five years had lower species richness, different bivalve composition, abundance and distributions, and a foreshore community dominated by bivalves, as compared to the intertidal region where no active farming occurred. Beaches that were actively farmed also had greater accumulations of organic matter and silt. Simplification of the intertidal benthic community, coupled with accumulations of organic matter and increased siltation, may have altered the ecology of the foreshore region used for intense shellfish harvesting. To access the foreshore for shellfish farming in a sustainable manner, studies are needed to determine the scale to which intensive use of the foreshore for shellfish purposes alone is feasible without undue harm to the environment.

Les changements du zooplancton lacustre à la suite des feux et des coupes à blanc dans la forêt boréale ont été évalués en 1996 en comparant trois groupes de lacs du Québec méridional : 20 lacs de référence aux bassins versants non perturbés, 9 lacs ayant subi en 1995 des feux de forêt sur la majorité de leur bassin versant et 9 lacs ayant eu en 1995 une coupe à blanc sur une partie de leur bassin versant. Les communautés zooplanctoniques ont été caractérisées par différentes variables : 1) la composition, la richesse spécifique et la densité du zooplancton, 2) la masse organique du limnoplancton (seston > 53 µm) et 3) le biovolume du méso- et macrozooplancton (> 250 µm). La richesse spécifique et les assemblages d'espèces en juillet 1996 ne différaient pas entre les groupes de lacs ; la variation inter-réplicats dans les assemblages d'espèces de chaque lac était très faible en comparaison de la variation inter-lacs. Par contre, la densité du zooplancton et la masse organique du limnoplancton étaient en moyenne significativement plus élevées dans les lacs de feux que dans les lacs de coupes et les lacs de référence. Le biovolume du méso et macrozooplancton suivait les mêmes tendances. L'effet des traitements (groupes de lacs : référence, feu, coupe) expliquait moins de 15 % de la variance totale de la masse organique du limnoplancton et du biovolume du méso et macrozooplancton tandis que les différences inter-lacs expliquaient la majorité (> 70 %) de la variance totale dans ces indicateurs. Les 15 % de variance résiduelle étaient attribuables à la variation inter-réplicats dans chaque lac. Notre étude préliminaire indique que les feux de forêts provoquent une poussée trophique du zooplancton et du limnoplancton mais n'ont pas d'effet sur la biodiversité et les assemblages d'espèces de zooplancton. Par contre, les coupes de forêt n'accroissent pas la biomasse du zooplancton en dépit d'une légère augmentation des nutriments, car les apports plus importants en carbone organique dissous après la coupe limitent la production biologique. Les changements limnologiques d'un lac à l'autre ont beaucoup plus d'importance que les feux et les coupes de forêts dans le contrôle environnemental du zooplancton des lacs de la forêt boréale.

Although pesticides provide benefits in our battle to control pests that destroy more than a third of all food, the use of pesticides also results in significant costs to public health and the environment. As many as 500,000 humans are poisoned annually by pesticides in the world; the United States alone reports about 45,000 human pesticide poisonings.

Pesticides have also caused many detrimental effects on agroecosystems and natural ecosystems. These include: (i) reducing and sometimes eliminating beneficial natural enemies that keep pest populations at low densities; (ii) increasing or decreasing reproduction in various animal populations; (iii) altering decomposition rates of soil organic matter; (iv) developing insecticide resistance in pests, which results in increased pesticide use and additional crop losses; and (v) eliminating honey bee and other bee populations in certain regions thus reducing crop yields and quality. Pesticides also have had major impacts on fish, bird and mammal populations.