Invasive Plant Research Articles

Efficacy of invasive plant powders and inert dusts against Sitophilus zeamais (Motschulsky) in wheat grain

Cereal grain insect pests, specifically Sitophilus zeamais, pose significant challenges to farmers and distributors worldwide, leading to substantial economic losses. Traditional pest control methods often rely on fumigants, raising environmental and health concerns. As an alternative, this study explores the efficacy of unconventional repellents derived from five invasive plant species powders and inert dusts such as wood ash, quartz sand, and zeolite in controlling S. zeamais infestations. The study employs laboratory experiments to evaluate the repellent effects of these substances on adult weevils and progeny emergence on wheat grain under different environmental conditions. Results indicate that plant powders showed some repellent effect (average significant difference in live weevil counts between treated and untreated grain was 13.4 %) and mortality rate (mostly around 20 %), but they were less effective compared to the well-known substances such as SilicoSec® and wood ash (both over 80 % mortality). Similar effects were observed in the progeny emergence experiment. Despite the lower effectiveness compared to conventional substances, the combined application of plant powders with other low-risk methods like the decreasing of temperature and humidity may offer viable pest management strategies in certain scenarios. Additionally, the study underscores the need for further exploration of alternative plant species and the potential for synergistic effects when combining repellent substances.

Standards‐based evaluation inform ecological restoration outcomes for a major mining activity in a global biodiversity hotspot

The International Principles and Standars for the Ecological Restoration and Recovery of Mine Sites were used to assess the restoration quality of one of the world's largest mines, located in the world's most biodiverse temperate forest. Quantitative analysis of longitudinal data spanning 35 years scored restoration quality at 2‐stars against a 5‐star forest ecosystem restoration target, with little indication of improvements from adaptive management. Two‐thirds of indicator plants were significantly under‐represented in early‐stage restoration and declined with age. Most plant species were effectively absent, including key structural species. Invasive plants and native legumes were persistently overabundant. Time required for the maturation of tree species will prevent the production of fundamental ecosystem features for well over a century (e.g. hollows and fallen logs), inhibiting functional fauna return (reptiles, bats, and conservation priority cockatoos in particular). The significantly different outcome compared with previous assessments is due to the age of restoration assessed and previous assumptions that early‐stage success indicate that restoration is on the correct, prolonged trajectory toward full ecological restoration. However, previous assessment methods did not consider many key metrics of the standards, nor accurately predict future restoration trajectory. In particluar, initial plant species richness (the only measure of biodiversity in the company's restoration completion criteria) did not reflect future restoration quality. These substandard restoration outcomes may result from removing the deep, multi‐layered bauxitic substrate on which the ecosystem evolved and establishing restoration on shallow topsoil over a more homogenized, impervious substrate. This study demonstrates the value of a robust, adaptable multi‐factor framework and methodology to evaluate restoration outcomes.

Geographic variation in leaf traits and palatability of a native plant invader during domestic expansion.

Like alien plant invasion, range expansion of native plants may threaten biodiversity and economies, rendering them native invaders. Variation in abiotic and biotic conditions across a large geographic scale greatly affects variation in traits and interactions with herbivores of native plant invaders, which is an interesting yet mostly unexplored issue. We used a common garden experiment to compare defensive/nutritional traits and palatability to generalist herbivores of 20 native (23.64° N-30.18° N) and introduced range (31.58° N-36.87° N) populations of Reynoutria japonica, which is a native invader following range expansion in China. We analyzed the relationships among herbivore pressure, climate, plant chloroplast haplotypes, leaf traits, and herbivore performance. Of the 16 variables tested, we observed range differences in 11 variables and latitudinal clines in nine variables. In general, herbivores performed better on the introduced plants than on the native plants, and better on the high-latitude plants than on the low-latitude plants within the introduced populations. Three key traits (leaf thickness, specific leaf area, and carbon-to-nitrogen [C:N] ratio) determined palatability to herbivores and were significantly associated with temperature and/or precipitation of plant provenance as well as with plant haplotypes but not with herbivore pressure. Our results revealed a causal sequence from plant-range-based environmental forces and genetic context to plant quality and palatability to herbivores in R. japonica. These findings suggest a post-introduction evolution of R. japonica, which may partly explain the colonization success of this important native, but invasive plant.

Autonomous suction harvesting as a novel approach to aquatic invasive plant control

Autonomous suction harvesting as a novel approach to aquatic invasive plant control

Invasion stage and competition intensity co-drive reproductive strategies of native and invasive saltmarsh plants: Evidence from field data

Biological invasion poses a significant threat to biodiversity conservation and also results in substantial economic loss including the excessive cost of management to control it. Still, its impact on plant sexual reproduction strategies remains underexplored in natural settings. We conducted a field experiment on native Phragmites australis and invasive Spartina alterniflora in Bohai Bay and assessed plant size (aboveground biomass and height) and sexual reproduction (ear biomass, reproductive allocation, etc.) in conjunction with water and soil properties. The results showed that during the early stage of invasion, the two species declined in size and sexual reproduction, with S. alterniflora showing a lesser decline than P. australis. However, in the late stage of invasion, S. alterniflora maintained its plant size by reducing its investment in sexual reproduction. Moreover, significant reproductive allometries were demonstrated by S. alterniflora under different competition intensities. P. australis displayed heightened sensitivity to water properties and soil non-resource conditions, while S. alterniflora adapted its inherent traits and environmental tolerance. S. alterniflora allocated more resources to thriving as an individual, while P. australis prioritized reproduction by increasing seed production. Overall, this study revealed the reproductive strategies that invasive and native species employ in response to competition and environmental factors, thereby offering crucial insights for conservation and management efforts.

Latitudinal trends in an invasive plant: genetic differentiation, phenotypic plasticity, and the effects of heavy metals and herbivores on growth, defence, and reproductive characteristics

Abstract Background and Aims Invasive species usually demonstrate remarkable adaptability across diverse environments, successfully inhabiting a wide variety of regions. This adaptability often links to genetic differentiation and phenotypic plasticity, leading to latitudinal trends in phenotypic traits. In this study, we collected seeds of invasive plant Phytolacca americana from different latitudes and planted them in homogeneous gardens to investigate the latitudinal variation of P. americana phenotypic traits and to evaluate the effects of herbivory and heavy metals on plant growth, defence, and reproductive characteristics. Methods P. americana seeds from different latitudes were planted in a homogeneous garden. For the experimental treatment, the seeds were divided into four groups: a heavy metal treatment group and its corresponding control group, and a cover treatment group with its corresponding control group. After the fruits matured, their growth, reproduction, and defence indicators were measured. Key Results Significant latitudinal trends were observed in P. americana’s growth and defence characteristics, including changes in branch number, underground biomass, total biomass, and leaf tannin content. Compared to previous field surveys on P. americana, our study found that the latitude trends in growth structure and defence traits were consistent. But the latitudinal trend of reproductive structure is different. Moreover, heavy metals and herbivory substantially influenced the plant’s growth, reproduction, and defence mechanisms, further shaping its latitudinal patterns. Conclusions The observed phenotypic variations in P. americana across latitudes can be largely attributed to the synergistic effects of phenotypic plasticity and genetic variation. At a broader geographical scale, adaptations to heavy metal stress and herbivory pressure among different P. americana populations involve distinct trade-offs related to growth, reproduction, and defence strategies.

Methanization Test of Water Hyacinth and Azolla in Co-digestion and Fertilizing Value of Digestates in Benin (West Africa)

Faced with the need for an alternative energy source following the extreme pressure exerted on woody resources accompanied by the increase of aquatic pests which invade water resources, the construction of mini reactors producing clean energy, biogas based on these invasive plants becomes a challenge. This investigation aims to assess the methane production potential of water hyacinth and Azolla in co-digestion and the fertilizing quality of the digestates obtained. A bio methanization test based on various combinations of organic substrates composed of water hyacinth and Azolla alone or in co-digestion under laboratory conditions at mesophilic temperature and neutral pH after 27 days was carried out. The source of enrichment in anaerobic microorganisms for fermentation processes in micro bioreactors consists of fresh pig manure. It appears that the combination of organic substrates including 75% of water hyacinth generated the maximum quantity of methane which is 1234 liters for one ton of organic substrates. This methane production is 1.93 times greater than that of the bioreactor containing water hyacinth alone, 1.90 times that containing azolla, 1.5 times that containing 25% water hyacinth +75% azolla then 3.04 times that containing the bioreactor composed of a high proportion of crushed Azolla filiculoides. The digestates are rich in N, P, K, Ca and Mg and had an amending power according to the NFU 44051 standard. For the construction of bioreactors with aquatic pests for the benefit of communities, co-digestion with a combination of substrates with a high proportion of water hyacinth is suggested.

Modeling the Effects of Temperature and Limiting Nutrients on the Competition of an Invasive Floating Plant, Pontederia crassipes, with Submersed Vegetation in a Shallow Lake.

The potential for a non-native plant species to invade a new habitat depends on broadscale factors such as climate, local factors such as nutrient availability, and the biotic community of the habitat into which the plant species is introduced. We developed a spatially explicit model to assess the risk of expansion of a floating invasive aquatic plant species (FAV), the water hyacinth (Pontederia crassipes), an invader in the United States, beyond its present range. Our model used known data on growth rates and competition with a native submersed aquatic macrophyte (SAV). In particular, the model simulated an invasion into a habitat with a mean annual temperature different from its own growth optimum, in which we also simulated seasonal fluctuations in temperature. Twenty different nutrient concentrations and eight different temperature scenarios, with different mean annual amplitudes of seasonal temperature variation around the mean of the invaded habitat, were simulated. In each case, the ability of the water hyacinth to invade and either exclude or coexist with the native vegetation was determined. As the temperature pattern was changed from tropical towards increasingly cooler temperate levels, the competitive advantage shifted from the tropical FAV to the more temperate SAV, with a wide range in which coexistence occurred. High nutrient concentrations allowed the coexistence of FAV, even at cooler annual temperatures. But even at the highest nutrient concentrations in the model, the FAV was unlikely to persist under the current climates of latitudes in the Southeastern United States above that of Northern Alabama. This result may have some implications for where control efforts need to be concentrated.

Reconstructing the biological invasion of noxious invasive weed Parthenium hysterophorus and invasion risk assessment in China.

Invasive alien plants (IAPs) present a severe threat to native ecosystems and biodiversity. Comprehending the potential distribution patterns of these plant invaders and their responses to climate change is essential. Parthenium hysterophorus, native to the Americas, has become an aggressively invasive species since its introduction to China in the 1930s. This study aims to collect and reconstruct the historical occurrence and invasion of P. hysterophorus. Using the optimal MaxEnt model, the potential geographical distributions of P. hysterophorus were predicted based on screened species occurrences and environmental variables under the current and three future scenarios in the 2030s, 2050s, and 2070s (i.e., SSP1-2.6, SSP2-4.5, and SSP5-8.5), and the invasion risk of P. hysterophorus in Chinese cities, croplands, forests, and grasslands was assessed. The results show that: (1) The species initially invaded highly suitable areas and further spread to regions with non-analogous climate conditions. (2) Under the current climatic conditions, the overall potential distribution of P. hysterophorus is characterized by more in the southeast and less in the northwest. Climate variables, including mean annual temperature (bio1), precipitation in the wettest month (bio13), isothermality (bio3), and temperature seasonality (bio4), are the primary factors influencing its distribution. (3) The potential distribution of P. hysterophorus will expand further under future climate scenarios, particularly toward higher latitudes. (4) Forests and crop lands are the areas with the most serious potential invasion risk of P. hysterophorus. Therefore, we suggest that the government should strengthen the monitoring and management of P. hysterophorus to prevent its spread and protect agro-ecosystems and human habitats. Depending on the potential risk areas, measures such as quarantine, removal, and publicity should be taken to mitigate the threat of P. hysterophorus invasion and to raise awareness of P. hysterophorus invasion prevention.

Naturalized species drive functional trait shifts in plant communities

Despite decades of research documenting the consequences of naturalized and invasive plant species on ecosystem functions, our understanding of the functional underpinnings of these changes remains rudimentary. This is partially due to ineffective scaling of trait differences between native and naturalized species to whole plant communities. Working with data from over 75,000 plots and over 5,500 species from across the United States, we show that changes in the functional composition of communities associated with increasing abundance of naturalized species mirror the differences in traits between native and naturalized plants. We find that communities with greater abundance of naturalized species are more resource acquisitive aboveground and belowground, shorter, more shallowly rooted, and increasingly aligned with an independent strategy for belowground resource acquisition via thin fine roots with high specific root length. We observe shifts toward herbaceous-dominated communities but shifts within both woody and herbaceous functional groups follow community-level patterns for most traits. Patterns are remarkably similar across desert, grassland, and forest ecosystems. Our results demonstrate that the establishment and spread of naturalized species, likely in combination with underlying environmental shifts, leads to predictable and consistent changes in community-level traits that can alter ecosystem functions.

Biochar-Supported Titanium Oxide for the Photocatalytic Treatment of Orange II Sodium Salt

Recent improvements in advanced technology for toxic chemical remediation have involved the application of titanium oxide nanoparticles as a photocatalyst. However, the large energy bandgap associated with titanium oxide nanoparticles (3.0–3.20 eV) is a limitation for their application as a photocatalyst within the solar spectrum. Various structural modification methods have led to significant reductions in the energy bandgap but not without their disadvantages, such as electron recombination. In the current investigation, biochar was made from the leaves of an invasive plant (Acacia saligna) and subsequently applied as a support in the synthesis of titanium oxide nanoparticles. The characterization of biochar-supported titanium oxide nanoparticles was performed using scanning electron microscopy, Fourier transformer infrared, X-ray diffraction, and Brunauer–Emmett–Teller analyses. The results showed that the titanium oxide was successfully immobilized on the biochar’s external surface. The synthesized biochar-supported titanium oxide nanoparticles exhibited the phenomenon of small hysteresis, which represents the typical type IV isotherm attributed to mesoporous materials with low porosity. Meanwhile, X-ray diffraction analysis revealed the presence of a mixture of rutile and anatase crystalline phase titanium oxide. The synthesis of biochar-supported titanium oxide nanoparticles was highly efficient in the degradation of Orange II Sodium dye under solar irradiation. Moreover, 83.5% degradation was achieved when the biochar-supported titanium oxide nanoparticles were used as photocatalysts in comparison with the reference titanium oxide, which only achieved 20% degradation.

Insect seed‐predator networks respond positively to restoration on a tropical island

Abstract When non‐native species invade ecosystems, coevolved plant–animal interactions and associated ecological functions are altered, often to the detriment of local biodiversity. While mutualistic interactions can benefit from—and assist with—ecological restoration through the removal of non‐native species, community‐level changes in antagonistic interactions due to restoration are less well understood. Insect seed predators provide important ecosystem functions, but can also have antagonistic effects through pre‐dispersal seed predation which can cause fruit abortion or premature fruit drop, potentially affecting plant community composition. Here, we used a network approach and data on trophic interactions from a large‐scale field experiment to investigate the differences in insect seed predator communities between native restored sites (where non‐native plants were removed) and unrestored sites dominated by non‐native plants on the island of Mahé, Seychelles. Restored sites contained more individuals and species of seed predators (up by 81% and 50% respectively), and experienced a greater predation intensity (1.06 ± 0.53 vs. 0.27 ± 0.09), and predator specialisation compared to unrestored sites. The proportion of predated samples was similar between treatments (~14%). Beta diversity, measured as species and interaction turnover, increased at restored sites. Synthesis and applications: Our findings imply that vegetation restoration generates marked biodiversity benefits on native seed predator communities and their interactions. However, removing non‐native plants did not result in the elimination of non‐native seed predators, which might require targeted control measures. Our results highlight the importance of considering the effects of restoration on antagonistic interactions, in addition to those reported for pollination and seed dispersal services. Management practices should aim to control plant invasions for the conservation of native plant communities that serve as resources and refugia both for mutualists (e.g., seed dispersers and pollinators) and native insect seed‐predator antagonists, both of which benefit native ecosystem function.

Systematic review of the uses of Cortaderia selloana (Poaceae), an invasive plant

Background and Aims: Cortaderia selloana, commonly known as Pampas Grass, manifests as an invasive plant across numerous countries with predominant studies focused on its control measures (physical, biological, and chemical approaches). Native to South America, this perennial tussock grass negatively impacts economic, environmental, and human health. This study aims to explore the diverse uses of Cortaderia selloana in geographical, cultural and ecological contexts, to provide insights into its applications, and to contribute to socio-economic and ecological understanding. Methods: This study comprises a systematic literature review based on the PRISMA 2020 guidelines. The search was conducted in EBSCOhost, ScienceDirect and Web of Science using the search question “("Cortaderia selloana") AND ("use" OR "purpose") NOT (“control”)”. Two researchers independently reviewed the titles and abstracts, applying predefined inclusion and exclusion criteria and extracting data on various aspects covered in the selected studies. Key results: A total of 88 articles were retrieved of which 16 were included in this systematic review. This study described diverse applications attributed to Cortaderia selloana, including wastewater treatment, composite synthesis, traditional medicine, bioremediation, biorefining, product development in the automobile industry and decoration. The utilization of this invasive species demonstrated socio-economic and environmental benefits, providing a novel perspective on transforming something harmful into a resource with various applications. Furthermore, the necessity for more research is emphasized, to enhance understanding of known applications and explore new potential uses. This study's main limitation is that it only includes peer-reviewed articles from selected databases. Conclusions: This research provides valuable insights into the diverse uses of Cortaderia selloana across geographical, cultural, and ecological contexts. These findings underscore the importance of considering both the beneficial applications and the challenges posed by this invasive species in order to inform balanced and sustainable management practices.

Conservation threats from tourism land grabs and greenwash

We report a new threat to conservation, namely land grabs by large tourism developers inside public protected areas. Locally, these tourism land grabs damage national parks through building footprints and access corridors, bringing habitat fragmentation, noise, light, roadkill, fire risk, and invasive plant and animal species and pathogens. They also create negative impacts on social equity and regional economies. The global tourism industry now perceives private development in public national parks as a mechanism to profit from land speculation, rather than merely monopoly provision of visitor services. Investment funds now use tourism, often with socialwashing components, as a political lever for land grabs. International “nature positive” marketing by tourism industry associations and multilateral tourism advocacy organisations is greenwash: it lacks substance, and aims to coopt conservation organisations.

Does decline and recovery process affect clonal and genetic diversity of a coastal plant population?

The evaluation of genetic diversity is important for the conservation of species. However, changes in genetic diversity during conservation are complex processes that depend on the characteristics of the species and environment. To evaluate the changes in genetic diversity from decline to recovery, we surveyed the coastal herb Calystegia soldanella in areas with varying degrees of non‐coastal plant invasion. First, to evaluate genetic diversity before the conservation measures, the spatial clonal structure of adults was investigated in a population invaded by non‐coastal plants. Second, to evaluate genetic diversity after the conservation measures, the regenerated individuals were investigated in the restoration plot. Moreover, to predict future genetic diversity without conservation measures, the effects of non‐coastal plant invasion on the production and genetic diversity of seeds were investigated using individuals from areas with various levels of non‐coastal plant invasion. In the adult population, 16 genets were identified in an 80 m × 4 m area. The maximum genet size was 30.3 m, suggesting the importance of clonal reproduction for population maintenance. In the restoration plots comprising 10 m × 10 m × 3 replicates, many seedlings (1.14 ramets/m2) emerged, resulting in high clonal diversity compared to that of the adult population. Therefore, the biomass and genetic diversity were rapidly restored at the beginning of the conservation practice. Non‐coastal plant invasion did not affect the genetic diversity of the seeds. However, it significantly reduced seed production. This suggests that non‐coastal plant invasion reduces sexual reproduction, resulting in the long‐term loss of genetic diversity.

Evaluating spectral properties of invasive plant species in Kentucky recreation areas

ABSTRACT This study examines the spectral characteristics of two invasive plant species, Amur honeysuckle (Lonicera maackii) and Callery ‘Bradford’ pear (Pyrus calleryana Decne), in central Kentucky’s recreational areas. Using a combination of spectrometer, satellite (National Agriculture Imagery Program (NAIP)) and unmanned aerial vehicle (UAV) data, this study investigated the correlation between leaf locations and normalized difference vegetation index (NDVI), as well as the impact of terrain features on vegetation indices. Significant variations in NDVI and normalized difference red-edge (NDRE) index values across study areas and leaf positions were observed. Terrain attributes, particularly slope and aspect direction, significantly influenced vegetative indices in one study site. Weak to moderate correlations were found between the spectrometer and UAV-derived NDVI and NDRE values. Additionally, the study highlighted the feasibility of upscaling UAV data for NAIP imagery comparison, reaffirming the superior accuracy of UAV imagery in assessing vegetation health. This integration of remote sensing techniques offers valuable insights into the spectral characteristics of invasive plants, essential for their effective mapping and management.

Plant invasion down under: exploring the below-ground impact of invasive plant species on soil properties and invertebrate communities in the Central Plateau of New Zealand

AbstractThe 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.

The Composition and Diversity of Soil Microbial Communities Associated With the Invasive Plant Solidago canadensis Vary Across Locations and Time Since Invasion

ABSTRACTAimPrevious local‐scale research (within plots or landscapes) has shown that invasive plants can alter the composition and diversity of soil microbial communities, with potential feedback effects on their own invasion success. However, the broader ecological patterns of these interactions across different invasion timescales and geographic regions remain poorly understood. This study investigated whether the composition and diversity of soil microbial communities associated with Solidago canadensis (Canada goldenrod) invasion vary across both population residence times and geographic locations.LocationSouth‐eastern China.TaxonSoil fungal and bacterial communities and S. canadensis.MethodsWe collected rhizospheric soil of S. canadensis, nonrhizospheric soil and adjacent uninvaded soil from each of 36 populations of S. canadensis with varying residence times (8–89 years), totalling 108 samples. We extracted DNA from these samples and sequenced the V3–V4 region of the bacterial 16S rRNA gene and the ITS2 region of the fungal rDNA. We analysed the DNA sequences to assess whether variation in α‐diversity, β‐diversity, arbuscular mycorrhizal fungi (AMF) richness and the ratio of AMF to plant pathogens in the soil microbial communities varied with S. canadensis population residence time, latitude and longitude.ResultsThe α‐diversity and β‐diversity of soil fungal and bacterial communities significantly varied with S. canadensis residence times, latitude and longitude. In locations where S. canadensis had been established for longer periods, there was an increase in AMF richness and a decrease in plant pathogens in the rhizospheric soil. Fungal diversity in rhizospheric soils was positively correlated with longitude, while bacterial diversity in rhizospheric and nonrhizospheric soils was positively correlated with both latitude and longitude.Main ConclusionsThese findings indicate that the time since invasion and geographical location can both significantly influence the composition and diversity of soil microbial communities associated with invasive plant species.

Invasive Glossy Buckthorn (Frangula alnus) Has Weak Impact on Native Understory Plant and Saprophagous Macroarthropod Communities

Glossy buckthorn (Frangula alnus Miller) is an invasive alien plant species (IAPS) rapidly expanding in North America but is largely understudied compared to the common buckthorn (Rhamnus cathartica). Our study investigated the effects of a 27-year-old F. alnus invasion on native understory plant and saprophagous macroarthropod communities in a wet deciduous woodland in Southern Québec, Canada. We hypothesized a decreased taxonomic diversity and a change in community composition of both indicator taxa with increasing F. alnus density. The understory plant and saprophagous macroarthropod communities were characterized, respectively, through vegetation surveys and pitfall trapping across a density gradient of 43 plots invaded by F. alnus. Our results demonstrated that F. alnus did not exert a strong influence on species community composition, although the homogenization of understory plant communities was observed. Despite several decades of F. alnus invasion at our study site, the consequences on the selected indicator taxa were overall relatively small, suggesting that the magnitude of effects is variable. We suggest that further investigation at a larger scale should be performed to evaluate the effect of F. alnus on a broad diversity of indicators and understand any context dependency.

Integrating UAV imagery and machine learning via Geographic Object Based Image Analysis (GEOBIA) for enhanced monitoring of Yucca gloriosa in Mediterranean coastal dunes

Effective monitoring and early detection of invasive alien plant species (IAPs) are crucial for mitigating their spread and safeguarding native habitats. Unmanned Aerial Vehicles (UAVs) offer a cost-efficient solution, providing high resolution images. In this study, we aimed to develop a semi-automated methodology using a machine learning algorithm, spatial metrics, and clustering techniques on UAV images to monitor, map, and suggest management measures to counteract Yucca gloriosa, an invasive plant colonizing coastal fixed dunes in central Italy.UAV flights were conducted using two drones: one for the visible spectrum and the other for multispectral bands (Blue, Green, Red, Red Edge, and Near Infrared) along with a Digital Surface Model (DSM). Derived vegetation indices were also utilized. For mapping Y. gloriosa distribution, a Geographic Object Based Image Analysis (GEOBIA) approach was applied to the orthophoto segmentation, followed by a Random Forest algorithm in a training phase, considering three variable combinations (DSM + vegetation indices, DSM + spectral bands, DSM + mixed variables). The most accurate Y. gloriosa map was used to suggest management measures combining the spatial pattern of invaded patches (size, height, isolation level, and aggregation degree) and a mixed clustering approach (hierarchical and partitioning).The results highlighted that the most accurate prediction map was based on the DSM + mixed variables dataset, showing the important role of using a combination of spectral bands and vegetation indices. In all three cases, the DSM emerged as the pivotal variable for discriminating Y. gloriosa from the surrounding environment. Additionally, our results demonstrate the advantages of incorporating vegetation indices in discerning the target invasive alien plant (IAP) from the broader environment, particularly considering its distinctive photosynthesis process and biomass production. From a managerial standpoint, our pilot study indicates that the UAV-based mapping methodology represents an optimal balance between field efforts and costs. This approach allows for the precise identification of containment and removal areas of Y. gloriosa, without compromising the accuracy of the method. The generated prediction maps also hold potential significance for the conservation of coastal dune ecosystems, providing a promising tool for the effective management of invasive species and biodiversity conservation by suggesting management measures for Y. gloriosa.