Biological Invasions

Müllerová, Jana; Brundu, Giuseppe; Große-Stoltenberg, André; Kattenborn, Teja; Richardson, David M.

doi: 10.1007/s10530-023-03150-zpmid: N/A

Processes that drive plant invasions play out across multiple spatial and temporal scales. Understanding individual steps along the introduction-naturalization-invasion continuum and its drivers is crucial for management. This review, targeting the broad audience of invasion scientists, field ecologists and land managers, summarizes the state-of-the-art and potential of remote sensing (RS) in plant invasion science and management. It identifies challenges and research gaps, discusses the discrepancies between technology, science and practice, and suggests ways of addressing some of these issues. Mapping, modelling and predicting invasion processes across scales is a major challenge since they are dynamic and highly complex. Integration of RS data collected at different spatial and temporal scales (“rocking” across scales) has the potential to elucidate the dynamics of invasions and to reveal its drivers, thereby improving the efficiency of control measures. Increasing spatial/temporal resolution of imagery from satellites and drones has much potential to (i) precisely identify even less conspicuous invasive species; (ii) map invasion dynamics; and (iii) provide information on environmental variables and landscape structure at scales fine enough to capture underlying ecological processes. Until now, RS research has focussed primarily on spatio-temporal patterns of plant invasions. Other more challenging topics, such as early monitoring, and revealing the invasion mechanisms and impacts have received less attention. Despite the power of RS technology and recent developments, large discrepancies remain between possibilities and actual implications in research and practical management of invasions. Although recent technological advances, such as powerful algorithms, cloud solutions, and data streams from citizen science, might overcome some limitations, the mutual dialog among field ecologists, managers, invasion scientists and RS specialists remains crucial; our review contributes to such communication.

Borokini, Israel T.; Kortz, Alessandra; Anibaba, Quadri A.; Witt, Arne; Aigbokhan, Emmanuel I.; Hejda, Martin; Pyšek, Petr

doi: 10.1007/s10530-023-03140-1pmid: N/A

Biological invasions remain one of the greatest threats to biodiversity and livelihoods, and are predicted to increase due to climate change and globalization. In this study, we produced a comprehensive checklist of alien plants in Nigeria from online flora databases, herbarium records, published field surveys, and questionnaires administered to botanical gardens. The resulting alien flora was classified into naturalized, invasive, and cultivated plants. We then fitted a random forest model to identify the attributes which facilitate the naturalization of alien plants in Nigeria. We also used separate chi-squared tests to investigate if the frequency of these attributes is significantly different between the naturalized and invasive plants. The results include 1,381 alien plant taxa, comprising 238 naturalized, 190 invasive, and 953 cultivated species. The naturalized and invasive plants (428 species) are from 91 families, with Fabaceae and Poaceae having the highest representations. The random forest model showed that life forms and local economic uses were the most important drivers of alien plant naturalization in Nigeria. Chi-squared tests revealed a non-random distribution of life forms, higher frequencies of naturalized plants from the Indomalaya and the Neotropics, greater introductions during the British colonial rule, and that naturalized species are mostly used for medicinal, ornamental, food, or animal fodder purposes. Naturalized and invasive plants were recorded in all regions of Nigeria and are mostly found in urban and agricultural landscapes. This baseline information can support further ecological studies and conservation actions in Nigeria.

Kilawe, Charles Joseph; Baltazary, Isaack Severin; Malila, Barnabas Philip; Lyimo, Paulo John; Mwakalukwa, Ezekiel Edward

doi: 10.1007/s10530-023-03136-xpmid: N/A

The last remnants of lowland forests in eastern Africa are biodiversity hotspots as they host a unique set of endemic animal and plant species. However, the diversity of the forests is threatened by man-made disturbances, including the introduction of non-native plant species. Here, we assessed the current extent and drivers of the spread of the invasive neotropical tree, Cedrela odorata L., introduced to Kimboza Forest Reserve in 1957 and 1960. We also assessed the impacts of the invasion on the composition of native tree recruitment (height < 0.5 m). The extent of invasion and drivers was assessed in 107 square plots (10 × 10 m) and 240 subplots (2 × 2 m) distributed systematically throughout the forest. The impact of C. odorata was assessed in 24 paired square sample plots (10 × 10 m) that were established in forest patches invaded and uninvaded by C. odorata. By 2017, adult C. odorata trees (diameter at breast height (DBH) ≥ 10 cm) occurred in 43% of plots and comprised, on average, 32% of the stems of all tree species and 28% of the basal area. The occurrence of C. odorata in the forest was significantly associated with the occurrences of wildfire and illegal logging, and significantly affected the density of native tree recruitments, Sorindeia madagascariensis and Rinorea arborea but did not affect the species diversity. Management actions are needed to reduce the negative impacts of invaded forest patches and prevent the uninvaded forest patches from invasion.

Gränzig, Tobias; Clasen, Anne; Fassnacht, Fabian Ewald; Cord, Anna; Förster, Michael

doi: 10.1007/s10530-023-03132-1pmid: N/A

Modeling the past or future spread patterns of invasive plant species is challenging and in an ideal case requires multi-temporal and spatially explicit data on the occurrences of the target species as well as information on the habitat suitability of the areas at risk of being invaded. Most studies either focus on modeling the habitat suitability of a given area for an invasive species or try to model the spreading behavior of an invasive species based on temporally or spatially limited occurrence data and some environmental variables. Here we suggest a workflow that combines habitat suitability maps, occurrence data from multiple time steps collected from remote sensing data, and cellular automata models to first reconstruct the spreading patterns of the invasive shrub Ulex europaeus on the island Chiloé in Chile and then make predictions for the future spread of the species. First, U. europaeus occurrences are derived for four time steps between 1988 and 2020 using remote sensing data and a supervised classification. The resulting occurrence data is combined with occurrence data of the native range of U. europaeus from the GBIF database and selected environmental variables to derive habitat suitability maps using Maxent. Then, cellular automata models are calibrated using the occurrence estimates of the four time steps, the suitability map, and some additional geo-layer containing information about soils and human infrastructure. Finally, a set of calibrated cellular automata models are used to predict the potential spread of U. europaeus for the years 2070 and 2100 using climate scenarios. All individual steps of the workflow where reference data was available led to sufficient results (supervised classifications Overall Accuracy > 0.97; Maxent AUC > 0.85; cellular automata Balanced Accuracy > 0.91) and the spatial patterns of the derived maps matched the experiences collected during the field surveys. Our model predictions suggest a continuous expansion of the maximal potential range of U. europaeus, particularly in the Eastern and Northern part of Chiloé Island. We deem the suggested workflow to be a good solution to combine the static habitat suitability information—representing the environmental constraints—with a temporally and spatially dynamic model representing the actual spreading behavior of the invasive species. The obtained understanding of spreading patterns and the information on areas identified to have a high invasion probability in the future can support land managers to plan prevention and mitigation measures.

Erickson, Richard A.; Thompson, Hannah M.; Kageyama, Stacie A.; Andriacchi, Grace M.; Cupp, Aaron R.; Patiño, Reynaldo; Amberg, Jon J.

doi: 10.1007/s10530-023-03137-wpmid: N/A

Natural resource managers use tools to control invasive species. In theory, stocking YY males or ZZ females would allow managers to skew sex ratios until populations collapse. In combination with other suppression methods, such as removal, this approach could be incorporated into Integrated Pest Management plans. For example, fishery managers have stocked YY males to control isolated non-native brook trout (Salvelinus fontinalis) populations. However, life histories and demographic factors (e.g., lifespans) vary across species and could affect the feasibility of skewing sex ratios as an effective control strategy for a given population. Likewise, some species may have sex determinations that do not allow population control through sex-skewing methods. We compared five representative aquatic invasive species with global invasion ranges for potential control by skewing the sex ratio through closed population simulations: red swamp crayfish (Procambarus clarkii), zebra mussels (Dreissena polymorpha), lake trout (Salvelinus namaycush), silver carp (Hypophthalmichthys molitrix), and Nile tilapia (Oreochromis niloticus). We determined that Nile tilapia, red swamp crayfish, and zebra mussels would be the most suitable to control through skewing the sex ratio assuming appropriate sex determination exists in the species. Lake trout could be eliminated by stocking YY males but would require either long stocking periods or high stocking numbers because of the long lifespan of the species. Silver carp populations were more difficult to crash because they live longer and produce many recruits. Broadly, these patterns demonstrated that short lived species lend themselves to control by skewing the sex ratio.

Adelino, José Ricardo Pires; Lima, Marcos Robalinho

doi: 10.1007/s10530-023-03134-zpmid: N/A

Correlative niche models are commonly used in the prevention and management of invasive species. The climatic similarity between non-native and native environments is a necessary assumption for the maintenance of species niches, influencing ecological processes in the persistence of non-native species in novel environments. Spatial patterns derived from distribution models provide a cost-effective method for predicting the occurrence of invasive species, but these models also allow the investigation of processes in the current patterns of non-native species occurrence. Here we used a literature review and niche modeling to investigate the introduction pathway and niche dynamics for non-native vertebrate species in Brazil. We found that environmental enhancement and commodity species are the primary pathways of introduction. Because our model indicated the coastal regions of Brazil as suitable for vertebrate introductions, and these pathways are associated with the animal trade, we highlight that port facilities are key points for species introductions. Non-native species at the early invasive stages showed a higher prevalence of niche unfilling, while those at the later invasive stages showed niche expansion. Also, recent introductions occurred in the margin of suitable climatic conditions, while later introductions generally occurred outside analog climatic conditions. This result emphasizes the significant role of niche shift and climatic conditions in the initial stages of the invasion process as a proximate factor in promoting species persistence.

Davis, Robert A.; Seddon, Philip J.; Craig, Michael D.; Russell, James C.

doi: 10.1007/s10530-023-03133-0pmid: N/A

Invasive rats are the biggest threat to island biodiversity world-wide. Though the ecological impacts of rats on insular biota are well documented, introduced rats present a difficult problem for detection and management. In recent decades, improved approaches have allowed for island-wide eradications of invasive rats on small-medium sized islands and suppression on large islands, although both these still represent a formidable logistical and financial challenge. A key aspect of eradication or suppression and ongoing management is the ability to detect the presence of rats, especially at low densities. Here we review recent developments in the field of rat surveillance and summarise current published literature to recommend practices and the factors to consider when developing a surveillance program for either eradication or suppression plans. Of 51 empirical studies covering 17 countries, 58% were from New Zealand. Although detecting rats at low density is extremely challenging, advances over the past 15 years, have significantly improved our ability to detect rats. Motion-sensored cameras and rodent detection dogs have greatly improved our ability to detect rats at low densities, with cameras consistently showing an ability to detect rats at lower densities than other techniques. Rodent detection dogs are also able to reliably detect even an individual rat, although there are challenges to their widespread adoption, particularly in developing countries, due to the cost and skills required for their training and maintenance. New monitoring devices, the use of eDNA and drones represent current and future innovations to improve detection.

Bonino, Andrea; Miloch, Daniela; Nori, Javier; Leynaud, Gerardo C.; Lescano, Julián N.

doi: 10.1007/s10530-023-03135-ypmid: N/A

Amphibians inhabiting mountainous water bodies are frequently documented as the most affected by alien species, being trout one of the introduced aquatic predators that most affect them globally. Strikingly, there are some records of co-occurrence between native amphibians and introduced trout in the same water bodies. We intended to elucidate which variables at the landscape scale explain the occurrence of the endemic frog Boana cordobae in streams invaded by alien trout (Sierras Grandes, central Argentina). We surveyed mountainous streams occupied by alien trout, measuring landscape variables and recording the occurrence of B. cordobae and found co-occurrence in almost 20% of surveyed streams (n = 81). We used Generalized Linear Models and LASSO regression to relate amphibian occurrence in invaded streams to landscape composition and configuration variables. The presence of tussock grasslands around streams appears to be the most critical variable explaining co-occurrence between B. cordobae and trout in our study site. Our study contributes with specific elements relevant to consider for invaded streams management actions, suggesting that alien trout management should consider the spatial features surrounding streams to concentrate trout eradication efforts in sites where amphibian populations are more likely to recover.

Nikkel, Emma; Clements, David R.; Anderson, Delia; Williams, Jennifer L.

doi: 10.1007/s10530-023-03139-8pmid: 37854296

The threat of invasive species to biodiversity and ecosystem structure is exacerbated by the increasingly concerning outlook of predicted climate change and other human influences. Developing preventative management strategies for invasive plant species before they establish is crucial for effective management. To examine how climate change may impact habitat suitability, we modeled the current and future habitat suitability of two terrestrial species, Geranium lucidum and Pilosella officinarum, and two aquatic species, Butomus umbellatus and Pontederia crassipes, that are relatively new invasive plant species regionally, and are currently spreading in the Pacific Northwest (PNW, North America), an area of unique natural areas, vibrant economic activity, and increasing human population. Using North American presence records, downscaled climate variables, and human influence data, we developed an ensemble model of six algorithms to predict the potential habitat suitability under current conditions and projected climate scenarios RCP 4.5, 7.0, and 8.5 for 2050 and 2080. One terrestrial species (P. officinarum) showed declining habitat suitability in future climate scenarios (contracted distribution), while the other terrestrial species (G. lucidum) showed increased suitability over much of the region (expanded distribution overall). The two aquatic species were predicted to have only moderately increased suitability, suggesting aquatic plant species may be less impacted by climate change. Our research provides a template for regional-scale modelling of invasive species of concern, thus assisting local land managers and practitioners to inform current and future management strategies and to prioritize limited available resources for species with expanding ranges.

Osmundson, Douglas B.

doi: 10.1007/s10530-023-03138-9pmid: N/A

Relations between annual abundance of three introduced fishes and body condition of an endangered piscivore, Colorado pikeminnow Ptychocheilus lucius, in the upper Colorado River were assessed to aid prioritization of non-native fish control efforts. Relative condition (Kn: mass at a given length) was monitored during spring, 1991–2013. Positive and significant relations were found between annual mean Kn and backwater densities of two common non-native, small-bodied, cyprinid species in downstream reaches of the 293 km study area. High mean Kn in spring followed years when fall densities of fathead minnow Pimephales promelas and red shiner Cyprinella lutrensis were high. No such relation was found with a third species, sand shiner Notropis stramineus. These three species have dominated zero-velocity habitats since their introduction in the 1960s. No relation was found between mean Kn prior to spawning and subsequent abundance of Colorado pikeminnow young-of-the-year (YOY) 3 months post spawning, suggesting mean Kn was not a driver of fall YOY abundance. Based on predatory interactions with larval native fishes documented in the literature, red shiners were deemed detrimental to Colorado pikeminnow despite their food value. Sand shiners appeared benign: non-predatory and less important as food. Fathead minnows, however, might be beneficial. They appear non-predatory on fish larvae while providing an important food source for various Colorado pikeminnow life stages. Managers need to weigh these benefits when considering control efforts.