Biological Invasions最新文献

The impacts of invasive plants on arthropod communities are often reported to be negative and have predominantly been explored aboveground, but there is a paucity of information regarding what happens belowground. To address this gap, we compared soil properties and soil fauna communities associated with two native plant species (Leptospermum scoparium—mānuka and Chionochloa rubra—red tussock) and two invasive species (non-N-fixing Calluna vulgaris—European heather and N-fixing Cytisus scoparius—Scotch broom) in the Central Plateau of New Zealand. We expected that (1) at individual plant level soil properties would be different under invasive and native plant species, with higher soil nutrient concentrations under invasive species, especially N-fixing broom; (2) total abundance of soil fauna would be higher under invasive plant species, as generally positive impact of invasive plants on soil invertebrates is indicated in the literature; (3) invasive plants, and especially N-fixing broom, will be associated with greater abundances of soil decomposer groups. We found that soil properties and soil fauna assemblages did not cluster by plant invasive status as initially predicted. At individual plant level, there was similarity in soil conditions between mānuka and broom, and between red tussock and heather. The invasive N-fixer (broom) had positive effects on soil N availability, with higher N pool and lower C/N ratio in soil under this species. There were no consistent differences in total soil fauna abundance between invasive and native plants. Broom and mānuka were associated with higher abundances of Collembola, Oligochaeta and Diplopoda; heather and red tussock had higher abundances of Hymenoptera and Hemiptera. Significantly more Oligochaeta and Collembola under broom matched the prediction of invasive plants (and especially N-fixing invasives) being associated with greater abundances of decomposers. However, another important decomposer group—oribatid mites—did not show the same tendency. These results evidence that simplified generalizations regarding the impacts of invasive plants are unlikely to be justified, since the ecological effects of plant invasions are complex and do not always follow the same pattern. Therefore, we need to take into consideration the ecological context and the traits of individual plant species and target organisms in an unbiased manner to fully understand the impacts of plant invasions.

Invasive species are an increasing source of economic loss, costing nations billions of dollars annually. Significant financial resources are spent to manage invasive species, but few comprehensive syntheses of the economic expenditures associated with this management effort exist. As a relatively affluent developed country, the United States should serve as a model of how to both manage invasive species and, more critically, understand the economic costs of doing so. To begin understanding the scale of expenditures on invasive species in the U.S., our goal was to quantify spending on invasive species management at the state level. We contacted natural resource management officials from all 50 states following a standardized protocol. While 47 of the 50 states provided expenditures for at least one of the five years requested (2017–2021), the distribution of expenditures by state varied dramatically, suggesting that actual expenditures might be much higher than those reported. While most states shared annual expenditures, they varied by an order of magnitude from $28,370 for Connecticut to $118,695,389 for Washington. Specifically, a widespread lack of careful and consistent expense tracking and coordination within and between states made clear and correct evaluation difficult. While the expenditures we obtained are almost certainly a significant underestimate, they also represent a serious lack of accounting at a state level. Hence, better tracking and coordination, within and between states, will be critical to handle the ongoing invasive species crisis.

Wetlands around the world face unprecedented threats, including from invasive species. In North America, the invasive cattail hybrid Typha x glauca dominates wetlands around the Laurentian Great Lakes; more recently it was found in high abundance across the central and eastern Prairie Pothole Region, an area that includes one of the world’s largest wetland complexes. Surveys of the Typha hybrid zone have so far been largely conducted in areas where hybrids are well established, and it therefore remains unclear whether the range expansion of this invasive hybrid occurs after the establishment of its maternal species, T. angustifolia. We surveyed 50 wetlands in the western PPR and found that while 75% of plants were native T. latifolia, the second most common group was F₁ hybrids, which had greater abundance and occupancy than T. angustifolia despite the fact that T. angustifolia produces relatively few hybrid seeds; our findings therefore highlight the importance of long-distance dispersal for this hybrid range expansion. The distribution of hybrids combined with the paucity of non-F1 hybrids suggest that the western PPR represents a leading edge of the range expansion by invasive T. × glauca. Our results show that T. × glauca has the capacity for continued range expansion that does not rely on the presence of T. angustifolia, and the impacts of this range expansion should be monitored because of its potential to impede ecosystem services and reduce local biodiversity.

Few conifers are considered invasive in Europe, yet recent studies indicate that several species used for forestry display abundant regeneration and spread into surrounding natural habitats. Three species were identified as being particularly at risk in Belgium, but data is lacking regarding their dispersal. We characterized the recruitment curves of Tsuga heterophylla, Abies grandis and Thuja plicata. Isolated plantations were monitored and realized dispersal (i.e. seedlings and recruited regeneration) was recorded and measured over 750 m in different directions. We calculated the wave expansion rate and frontier expansion rate for each planting site and fitted dispersal kernels for each site and species. Regeneration was classified in three size categories (seedlings, saplings and trees above 1.5 m), and the recruitment distances were analyzed for each size class. The effect of the forest type (deciduous, coniferous, open or mixed) on the density of regeneration was also investigated with regression models. The recruitment curves varied greatly across sites, showing heterogeneous habitat suitability and uneven post-germination processes. Considering the frontier expansion rate, the three conifers appear to spread beyond documented threshold rate of invasiveness. Regeneration density was higher in coniferous forest type, as well as open areas for Tsuga heterophylla. An escape effect was noticed as mean and maximal dispersal distances of saplings and taller trees were greater than those of seedlings. Our study indicates that Tsuga heterophylla displays the highest risk of rapid spread into adjacent natural habitats, followed by Abies grandis. Thuja plicata faces more recruitment limitations.

Flooded areas can create temporary connections between adjacent drainages and are a relatively understudied pathway for the spread of aquatic invasive species. The Nonindigenous Aquatic Species Database’s Flood and Storm Tracker maps were developed to help natural resource managers with post-storm aquatic invasive species detection and assessment efforts. As of the summer of 2023, 16 Flood and Storm Tracker maps have been published from hurricanes and flooding events in the United States and territorial islands. Three regions along the coasts of the Gulf of Mexico and Atlantic Ocean had overlapping areas of repeated flood impacts, and fifteen pairs of adjacent river basins were potentially connected during floods. Each map had a median of 77 non-native freshwater taxa and a median of 3 U.S. prohibited species within their respective flood-impacted area. The Flood and Storm Tracker maps provide resource managers with information about new aquatic invasions due to potential flood dispersal that can assist with early detection and rapid response systems.

There are 230 UNESCO World Heritage Sites that were designated based on their important natural features. These represent some of the most iconic and important natural places on Earth, with immense value for biodiversity conservation, ecosystem service supply and cultural well-being. Many of these sites are degraded by anthropogenic drivers, including socioeconomic factors (population growth, poverty and tourism), extractive activities (logging, mining, and hunting), external threats (fire, climate change, land-use change, pollution), and biological threats (disease and invasive species). Of these, invasive species remain one of the most problematic for management, and once introduced, populations can grow exponentially and spread to other locations even when actively managed. Given the economic and environmental threats imposed by invasive species, we asked how they compare to the other anthropogenic threats. We reviewed the primary literature for each World Heritage Site and scored the prevalence of 12 different anthropogenic drivers. We found that invasive species rank as one of the most frequently identified threats and pose the greatest degree of concern compared to all other threats, on par with the threat from pollution and greater than logging, land-use change and climate change. We compared our scoring, based on review of the literature, with that of the UNESCO and IUCN monitoring reports. Although there was general agreement between these two assessments, the literature provided information on 55 sites not included in the monitoring reports. We further examine the invasive species examined in the articles and the degree of their perceived impacts on biodiversity, habitat, rare species, ecosystem function, tourism, and economic impacts. It is important that invasive species are well monitored and managed in WHSs to reduce their impacts and meet policy mandated targets and conservation goals.

Biological invasions are a major stressor on ecosystems worldwide, but tools to predict their predatory impact remain limited. Here, we quantified invader impacts using two complementary approaches: functional responses (to reveal per capita and multiple predator interaction strengths) and ecomorphology (to reveal trophic profiles and competitive overlap). We compared Mozambique tilapia Oreochromis mossambicus, a native southern African cichlid, and a near-trophically analogous invasive congener, the Nile tilapia Oreochromis niloticus. Both Nile tilapia and Mozambique tilapia exhibited a potentially prey population destabilizing Type II functional response. In both single and multiple predator pairings, invasive Nile tilapia had significantly greater prey consumption rates than native Mozambique tilapia, and thereby a greater predatory impact than its native congeneric. Attack rates were greater for Nile tilapia than Mozambique tilapia, with both species showing more similar handling times and maximum feeding rates. No evidence for multiple predator effects was detected within or between these species, and therefore impacts of both species increased additively in the presence of conspecific or heterospecific competitors. Morphological trait analyses found general differences between these two species, with the invasive Nile tilapia having distinctively larger lower jaw closing force, gill resistance and gill raker length, which facilitated greater feeding capacities over the native species. Trophic profiles predicted using morphological trait differences showed high dietary overlap and served as evidence for potential exploitative competition between the two species. These results reveal superior interaction strengths and ecomorphological trait profiles of an invasive over native species which could influence impact and native species replacement dynamics. Novel applications of functional response and ecomorphology provide complementary insights into predatory and competitive impacts from invasive species, aiding impact prediction across environmental contexts.

The invasive species Bubalus bubalis was introduced in Guaporé Biological Reserve in 1953. Since then, the buffaloes have become feral, posing a threat to the populations, communities, and natural ecosystems of the region. In the last decade, there has been no study or monitoring of the invasive population and its potential impacts. We utilized systematic flights and multitemporal remote sensing analysis to address (i) What is the distribution range, abundance and density of Asian buffalo in the protected area? (ii) How has this species changed the land scape in the protected area over the past 34 years? The population survey resulted in 4.782 ± 533.27 buffaloes within 966.22 km², population density of 4.9 ± 0.55 buffaloes per km². The study also identified a 51% expansion of occupied areas within the Guaporé Reserve over the last 10 years. The multitemporal remote sensing analysis revealed significant environmental changes over the years, resulting in 48% loss of naturally flooded areas in the region occupied by buffalo. The government must take urgent measures to develop and implement a plan to control and eradicate this invasive species.

Species arrival sequence in new habitats impacts plant community development. This ‘priority-effect’ is documented, but mechanisms by which early arriving plants dominate future communities are less clear, complicating our ability to predict community assembly under future climate warming and assess invasive species threats. This is particularly important for ecosystems that are vulnerable to invasive species, such as those of the Antarctic Peninsula. To test how phenological differences and arrival order affect community composition of invasive plants, we simulated maritime Antarctic climate conditions, and a warming scenario. We established monocultures of six species potentially invasive to the Antarctic Peninsula (three forbs and three grasses), which exhibit a range of germination times ranging from 22 and 68 d, and a mixed community of all species. Before entering a simulated winter, half of each monoculture (n = 10) received the full seed mixture while the other half received seeds of their respective starting species. During the following simulated growing season, we quantified if the community composition was influenced by arrival order and whether species germination and growth responses differed from their monocultures and starting species. Community compositions differed across all starting communities and were typically dominated by the starting species. Phenological differences influenced individual and total biomass and plant height, but faster germinating species did not consistently dominate the final plant community. Forbs and grasses negatively impacted each other’s biomass. Warming enhanced priority effects (more negative or positive). Phenological priority has ecologically relevant influences on community assembly, but its effect on plant growth is context dependent in terms of species and temperature conditions. In particular, our data suggest that phenological priority influences plant biomass and size while niche pre-emption affects seed germination. Future trajectories of polar terrestrial plant communities will depend on the arrival order of colonizing non-native plants and their germination rates.

Raw Water Transfer (RWT) schemes move large volumes of freshwater between separate waterbodies to supply water as a specific commodity. Water is translocated by complex purpose-built networks of pipelines, tunnels and water supply canals. RWTs form hydrological connections between waterbodies across various spatial scales, and create a pathway of introduction and spread for a diverse range of invasive non-native species (INNS). Though occurring globally in large numbers, RWTs are not currently well represented by the standard pathway classification framework adopted by the Convention on Biodiversity (CBD). At present, RWTs are included within the ‘corridor’ category, which denotes the natural spread of organisms to neighbouring regions through transport infrastructure i.e. navigable canals/artificial waterways. However, RWTs are not routes for vehicle transport, and species are translocated between often non-adjoining waterbodies by the intentional transfer of water, not via natural spread. We provide a background for the complex RWT pathway and evidence of INNS spread through RWT schemes globally, and explore several options for improved RWT classification within the CBD framework—we recommend that the current corridor category is modified slightly to accommodate the addition of RWTs as a distinct sub-category, as separate from a clearly defined ‘navigable canal/artificial waterways’ sub-category. Accurate classification will increase understanding and awareness of this high-risk pathway, and support much-needed insight into its distinct stakeholders and drivers. Further, delineating RWTs from navigable canals/artificial waterways will help to identify widespread opportunities for pathway management and policy development, in addition to supporting more accurate future assessments of the risks and economic costs of the corridor pathway category.