The study focused on the 278 municipalities of mainland Portugal and covered plants included in Portuguese Decree-Law No. 92/2019 or European Union Regulation No. 1143/2014, while excluding species relevant only to Portugal’s islands. The final mapping effort involved 96 species from 64 genera and 36 families. Most were terrestrial plants, accounting for 86% of the total, while 14% were aquatic or semi-aquatic. Grasses and herbs formed the largest growth-form category at 47%, followed by trees and shrubs at 29%, climbing plants at 5% and other forms at the remaining proportion. Asteraceae, Amaranthaceae, Fabaceae and Poaceae were the most represented families.

Occurrence data came from the Global Biodiversity Information Facility, the expert-led Flora-On project, research-grade iNaturalist observations, Pl@ntNet, scientific publications, postgraduate theses and unpublished records supplied by authors, collaborators and organizations involved in invasive-plant management. Information through May 2024 was included. Taxonomy was standardized using the GBIF Backbone Taxonomy; records referring only to the stored location of a specimen rather than its actual observation site were removed, as were records with spatial precision below 100 metres. Duplicate records for the same species within each municipality were collapsed so that richness represented the number of unique species recorded there.

The researchers used the 1-by-1-kilometre grid cells intersecting municipalities to estimate how extensively each species occupied the places where it had been detected. Oxalis pes-caprae had the highest mean occupancy, covering 7.53% of the relevant grid cells, followed by Arundo donax at 6.90% and Cortaderia selloana at 6.87%. Acacia longifolia and Arctotheca calendula ranked next, with mean occupancy of 5.58% and 5.88%, respectively, but were concentrated largely in coastal areas. A linear model found that the number of municipalities containing a species was significantly associated with its mean occupancy and accounted for 42% of the observed variation. This means national reach and the proportion of occupied cells within municipalities were related, but neither measure was a substitute for a direct assessment of abundance.

National coverage varied by species. Acacia dealbata had the broadest municipal distribution, appearing in 249 of the 278 municipalities, followed by Datura stramonium in 233, Arundo donax in 232, Phytolacca americana in 224, Oxalis pes-caprae in 213 and Cortaderia selloana in 208. Ailanthus altissima was recorded in 198 municipalities, Acacia melanoxylon in 190, Agave americana in 187 and Robinia pseudoacacia in 186. At the other end of the distribution, Alternanthera philoxeroides, Amaranthus hypochondriacus, Amaranthus muricatus and Baccharis halimifolia each appeared in only one municipality. Species with only a small number of records included a disproportionate share of aquatic or semi-aquatic plants, although the atlas alone could not determine whether a sparse record represented an emerging invasion or incomplete reporting.

To identify shared distribution patterns, the team characterized each species by the number of municipalities in which it occurred, the median and interquartile range of its distance from the coast, and the median and interquartile range of its latitude. Principal component analysis, with the first two components explaining 72.3% of the variance, was followed by k-means clustering, for which the elbow method was used to select the number of groups. Four clusters emerged. Twenty-six species were concentrated mainly in coastal areas, including Acacia saligna and Cotula coronopifolia. Fourteen had narrow ranges extending across no more than 33 municipalities and were generally found in central and northern areas, with Reynoutria japonica and Baccharis halimifolia as examples. Another 29 were moderately widespread, and the final 27 were mostly broadly distributed, averaging 145 municipalities each. A species such as Cortaderia selloana nevertheless remained relatively uncommon deep inland, illustrating how presence-only data at municipal scale can conceal finer geographic variation.

The mapped richness showed a clear coastal and urban concentration. Lisbon recorded 63 of the 96 species, narrowly ahead of Coimbra with 62, while Sintra had 58 and Figueira da Foz 55. Other relatively rich municipalities occurred around the Oporto metropolitan area, in cities including Viana do Castelo, and along the Algarve coast. Lower totals characterized parts of northeastern Portugal and some central and inland areas of Alentejo. Because Portugal’s population and economic activity are concentrated along the western and southern coasts, especially around Lisbon and Oporto, the geographic pattern is consistent with an important role for human activity and accessibility. The atlas measured association rather than causation, however, and did not experimentally test the processes responsible for the observed distribution.

A generalized least-squares model, fitted under an assumption of exponential spatial autocorrelation, explained 59% of the variation in municipality-level invasive-plant richness, expressed as a pseudo-R2. Four variables had statistically significant relationships at p < 0.05. Richness increased with municipality area, whose coefficient was 0.0478 with a standard error of 0.006, and with power-line density, whose coefficient was 0.4782 with a standard error of 0.231. It also increased as minimum distance to the coast decreased, with a coefficient of -0.0074 and standard error of 0.002, and as travel time to the nearest city shortened, with a coefficient of -0.0070 and standard error of 0.002. Larger municipalities can contain more habitats and a broader regional species pool, while the coastal and accessibility relationships align with the country’s concentration of people and economic activity. The role of linear infrastructure in facilitating plant invasion remains less well studied, and the significant power-line association does not establish that roads, railways or other transport corridors have the same effect.

Several tested variables were not significant in the final model. These included precipitation in the wettest month, the mean daily maximum air temperature of the warmest month, ruggedness, agricultural and forest cover, protected-area density, burnt area, soil pH, hydrographic-network density, railway density and several measures of sampling effort. The authors noted that averaging soil pH across heterogeneous soil types within a municipality may dilute local differences. They also observed that climate variables were weaker predictors than expected in this analysis, possibly reflecting the influence of human distribution and activity across mainland Portugal, although the observational model cannot establish which mechanisms produced the results. The inclusion of proxies for recording effort was intended to help distinguish biological patterns from differences in observation intensity, but those proxies cannot eliminate every sampling bias.

The atlas has important limitations. Its underlying records were assembled largely through opportunistic and citizen-science observation, so apparent absences may reflect low survey effort, restricted site access or poor detectability rather than true absence. Conspicuous species and well-visited urban areas may also be overrepresented. Most of the information came from presence records, and municipality-level richness does not show how many individuals are present, whether populations are expanding or how much ecological harm a species causes. The method also gives equal weight to every listed species even though their effects and management urgency can differ. A new record of one taxon may call for immediate investigation, while another may represent a geographically restricted occurrence; the richness map alone cannot make that distinction. The researchers therefore present it as a tool for locating potential invasion hotspots and identifying where field surveys are needed, not as a direct measure of invasion severity.

Despite these constraints, the database documents a national pattern that was previously fragmented among many sources. It shows that the 96 mapped species occur throughout mainland Portugal, with the highest recorded richness in coastal urban areas and the lowest totals in several inland regions. It also reveals sharply different national and municipal distribution profiles among individual taxa, from plants reported across most of the country to those represented by a single municipal record. For managers, those sparsely documented occurrences may justify targeted fieldwork to clarify whether they reflect early stages of invasion or gaps in observation. Continued systematic monitoring, collection of abundance data and species-specific risk assessments would be needed to turn the presence-based atlas into a more precise account of population size, ecological effects and management urgency.

Subject of Research: Spatial distribution and environmental correlates of invasive alien plant richness across mainland Portugal

Article Title: Diversity and distribution patterns of invasive alien plant species in mainland Portugal

Article References: Fernandes, R., Castro, A., Marchante, H., Marchante, E., & Capinha, C. (2025). Diversity and distribution patterns of invasive alien plant species in mainland Portugal. NeoBiota, 104, 139-162. https://doi.org/10.3897/neobiota.104.163291

Image Credits: AI Generated

DOI: 10.3897/neobiota.104.163291

Keywords: invasive plants, Portugal, biodiversity mapping, species richness, municipal distributions, occurrence records, coastal cities, power-line density, citizen science, plant invasions, Diversity, distribution

The study focused on Pannonian sand steppes within Kiskunság National Park in central Hungary. This priority habitat, protected under the European Union’s Habit Directive, consists largely of dry, nutrient-poor grasslands that historically supported little woody vegetation. Large tracts were converted to cropland during the nineteenth and twentieth centuries, and the surviving fragments are now under pressure from altered water regimes, intensified agriculture, abandonment of traditional grazing, and the spread of alien plants. The habitat is officially classified as being in an “unfavourable-bad” conservation status, meaning that it faces a substantial risk of further deterioration or disappearance.

Sand dropseed, or Sporobolus cryptandrus, first appeared in the study area in 2016 and then expanded rapidly. Unlike many invasive plants that require heavily disturbed ground, this C4 grass can invade intact, species-rich grassland. Its dense stands displace native perennial grasses, reduce plant diversity and homogenize the structure of the vegetation. Another alien species, common milkweed, was also present at the surveyed sites, although it generally favors degraded meadows, roadsides and formerly ploughed or overgrazed land. Native and introduced woody plants were simultaneously advancing into the grasslands as traditional grazing declined.

Researchers selected 48 plots, each measuring 25 by 25 meters, across the six study sites. The design deliberately included plots with little or no sand dropseed alongside heavily invaded patches. In September 2024, teams of six or seven observers walked parallel transects through each plot and recorded every reptile seen, including its species, age class, sex, position and time. The investigators also measured the cover of sand dropseed, common milkweed and woody vegetation, then assigned each plot a naturalness score reflecting its plant composition, structure and ecological functioning.

Counting animals directly is notoriously difficult for reptiles. Many are elusive or cryptically colored, and their activity changes with temperature, particularly because they depend on external heat to regulate their bodies. The researchers therefore used single-visit N-mixture models, a statistical approach designed to estimate population abundance while explicitly accounting for imperfect detection. Vegetation variables were placed in the abundance component of the models, while operative temperature and observer effort were used to explain the likelihood that an individual present would actually be seen. Separate models were fitted for the two lizard species.

Surveyors recorded 56 Balkan wall lizards and 28 Eastern green lizards. The Balkan wall lizard appeared in 30 of the 48 plots and was detected more reliably than the Eastern green lizard, which appeared in 18 plots. Model results showed a statistically significant negative association between sand dropseed cover and Balkan wall lizard abundance. The effect of common milkweed was not significant. For the Eastern green lizard, invasive-plant cover had no significant effect, but increasing woody encroachment was associated with greater abundance. Mean detection probabilities were estimated at 0.82 for the Balkan wall lizard and 0.51 for the Eastern green lizard, while estimated mean densities were 48.5 and 11.2 individuals per hectare, respectively.

The results are consistent with the different ecological demands of the two reptiles. Balkan wall lizards in this region depend on open, sandy and loess grasslands with low, sparse vegetation. As sand dropseed expands, it creates more uniform stands that may offer less varied shade, refuge and thermal conditions. The invader also supports fewer and less diverse arthropod communities, potentially reducing prey availability and the habitat’s overall carrying capacity. By contrast, Eastern green lizards are generalists that occupy grasslands, forest edges and a wide range of wetter and drier environments. Shrubs and trees create the more structurally diverse habitat this species can exploit, even as they replace the treeless conditions favored by the wall lizard.

The study also illustrates why the impact of an invasive species cannot be inferred simply from the fact that it is spreading. A plant may transform habitat without affecting every resident in the same way, and vegetation encroachment can itself generate winners and losers. The authors note several limitations: the sampling was concentrated in only six sites, the number of plots was modest, and there was no temporal replication. Stratification by sand dropseed abundance may also have limited the precision of estimates for milkweed and woody encroachment. Nevertheless, complementary generalized linear mixed models assuming perfect detection produced patterns similar to the N-mixture results, supporting the main conclusions.

Because sand dropseed has already spread extensively, researchers argue that total eradication is unrealistic and that management should focus on preventing further expansion while limiting ecological damage. Mapping colonies and identifying the forces driving their spread could improve forecasting and early intervention. Restricting vehicle movement on sandy roads may help, because seeds are readily transported on tires. Small founder populations could potentially be removed manually, while grazing, mowing, burning, chemical treatment and combinations of these methods require urgent testing in larger stands. Repeated surveys across multiple seasons and years would also help determine whether the observed lizard responses persist as invasion progresses.

For now, the study provides an early warning from one of Europe’s most distinctive and threatened grassland types. Sand dropseed appears to be eroding the habitat of the Balkan wall lizard not merely by replacing native plants, but by simplifying the structure and food web on which the species depends. The Eastern green lizard’s apparent benefit from woody growth should not be mistaken for ecosystem recovery: shrubs can improve cover for a generalist while simultaneously pushing a threatened specialist out of its preferred habitat. Protecting Pannonian sand steppes will therefore require more than stopping the spread of a single invasive grass. It will demand active maintenance of open, thermally varied and prey-rich grassland, alongside targeted control of the plants and vegetation changes reshaping one of Central Europe’s vanishing ecological arenas.

Subject of Research: Effects of invasive sand dropseed and woody encroachment on two lizard species in Pannonian sand steppes

Article Title: Effect of plant-related threats on lizards of open sand steppes: a snapshot at the beginning of the spread of a novel invader

Article References: Mizsei, E., Adorjáni, C., Bancsik, B., Kovács, G., Rák, G., Babocsay, G., & Budai, M. (2025). Effect of plant-related threats on lizards of open sand steppes: a snapshot at the beginning of the spread of a novel invader. NeoBiota, 104, 95-111. https://doi.org/10.3897/neobiota.104.159611

Image Credits: AI Generated

DOI: 10.3897/neobiota.104.159611

Keywords: sand dropseed, Balkan wall lizard, Eastern green lizard, invasive plants, grassland degradation, Pannonian sand steppe, woody encroachment, reptile ecology, N-mixture models, Hungary, Effect, plant-related

The study, led by researchers working on Leptocoris soapberry bugs, documents how the introduction and movement of plants in the soapberry family (Sapindaceae) has reshaped the distribution and evolution of these specialised seed predators. In Australia, the native Leptocoris rufomarginatus was found feeding on ornamental Alectryon trees roughly 500 kilometres south of its previously published range, while in South Africa, the native Leptocoris mutilatus now occurs more than 1,000 kilometres beyond its historical distribution, sustained by invasive balloon vines and a planted Australian tree.

Soapberry bugs are hemipterans in the subfamily Serinethinae, specialised seed predators of sapindaceous plants. Their co-evolutionary history with soapberry hosts means they carry pre-adaptations that allow them to colonise novel, phylogenetically close host plants introduced by humans. When native insects adopt abundant non-native or extralimital hosts, they can undergo extralimital spread, expanding their geographic ranges well beyond historical limits.

In Australia, the researchers collected Leptocoris insects between 2022 and 2024 across New South Wales and the Northern Territory. Most Leptocoris rufomarginatus individuals were found on Alectryon tomentosus planted as ornamentals in the Greater Sydney region, well outside the natural range of the host trees. At two sites, the bugs were feeding on Alectryon coriaceus, a novel host record for the species. Meanwhile, the non-native Leptocoris vicinus, likely co-introduced with the ornamental tree Schleichera oleosa from Southeast Asia, remains localised at its initial introduction site in Darwin more than 60 years after its first discovery.

Species distribution models built using MaxEnt revealed vast areas of climatically suitable habitat for both native and non-native host plants beyond the current distributions of the soapberry bugs. For Leptocoris tagalicus, suitable areas for native hosts covered approximately 262,760 square kilometres, while non-native hosts covered about 331,765 square kilometres, with these areas overlapping almost completely. For Leptocoris rufomarginatus, roughly 189,426 square kilometres of suitable native host habitat lies outside and mostly southwards of the insect’s inferred historical range. For the introduced Leptocoris vicinus, an estimated 919,620 square kilometres of suitable habitat for its known hosts exists across northern and eastern Australia, suggesting that further range expansions by both host plants and insects are likely to continue.

In South Africa, Leptocoris mutilatus was collected from ten sites in Kruger National Park on native Cardiospermum corindum and invasive C. halicacabum, and from three extralimital sites in the Western Cape province on invasive C. grandiflorum and the planted Australian tree Alectryon connatus. The Western Cape records place the insect more than 1,000 kilometres outside its previously known distribution. Notably, this study provides the first record of Leptocoris mutilatus feeding on an Alectryon species.

Morphological measurements revealed significant differentiation in proboscis length among Leptocoris mutilatus populations feeding on different host plants. A two-way ANOVA showed that both host plant species and sex significantly predicted proboscis length. Insects collected from invasive C. halicacabum had significantly longer proboscides than those from other hosts, while those from native C. corindum had longer proboscides than those from A. connatus and invasive C. grandiflorum. Insects feeding on A. connatus had proboscides significantly shorter than those from the historical native range, suggesting contemporary evolutionary change since the adoption of this novel host.

Wing morphology also differed dramatically between populations. In the Western Cape, 97 percent of Leptocoris mutilatus individuals were short-winged and flightless, compared with only 12.5 percent in Kruger National Park. This pattern mirrors findings in North American Jadera haematoloma populations, where flightless morphs have shorter generation times and may be physiologically incapable of diapause, adapting to seasonal seed availability on isolated host patches. The high frequency of volant morphs in Kruger National Park likely reflects the proximity of multiple Cardiospermum host species and other abundant native hosts, promoting frequent movement between plants that fruit at different times of the year.

Perhaps the most striking finding came from laboratory no-choice mating trials. The researchers successfully hybridised the native Leptocoris tagalicus with the non-native Leptocoris vicinus, producing viable first-generation hybrids and backcrossed offspring, the first report of interspecific hybridisation for soapberry bugs under laboratory conditions. Genetic analysis based on 6,077 SNP loci confirmed the intermediate genomic ancestry of hybrid and backcross individuals. However, all first-generation by first-generation crosses produced eggs but no offspring, indicating substantial postzygotic reproductive isolation between the two species. Pairings involving Leptocoris rufomarginatus with either of the other species produced no hatchlings and no observed copulations, suggesting this larger, more arboreal species is too divergent to hybridise successfully.

The findings demonstrate how human-mediated plant dispersal affects the ecology, distribution, and evolution of native insects. The shared evolutionary history between soapberry bugs and sapindaceous host plants suggests that further changes in these insects’ distributions and adaptive responses to novel hosts are likely to occur. The researchers suggest that eradicating the small, isolated Leptocoris vicinus population in Darwin before it spreads could be an effective management option, and they call for future surveys to identify additional plantings of non-native host trees and to explore whether hybridisation among other soapberry bug species is being promoted by non-native and extralimital host plants worldwide.

Subject of Research: Human-mediated dispersal of soapberry host plants and its effects on the distribution and evolution of Leptocoris soapberry bugs

Article Title: Human-mediated plant dispersal changes insect distributions with potentially important evolutionary implications

Article References: Brown, L., Geraghty, D. M., Lambos, M., O’Hare, J. A., Delamotte, N. M., Carroll, S. P., & Le Roux, J. J. (2026). Human-mediated plant dispersal changes insect distributions with potentially important evolutionary implications. NeoBiota, 108, 145-170. https://doi.org/10.3897/neobiota.108.175185

Image Credits: AI Generated

DOI: 10.3897/neobiota.108.175185

Keywords: soapberry bugs, Leptocoris, host shifts, invasive plants, Sapindaceae, range expansion, hybridisation, proboscis length, species distribution models, Australia, South Africa, NeoBiota

The research, led by Prem Prakash Singh and Dibyendu Adhikari of the CSIR-National Botanical Research Institute in collaboration with the University of Lucknow, set out to build a resource-efficient surveillance workflow that municipal agencies could realistically adopt. The team focused on three invasive plants representing sharply different growth forms: Neltuma juliflora, a deep-rooted tree also known by its earlier scientific name Prosopis juliflora; Lantana camara, a dense woody shrub notorious across the tropics; and Parthenium hysterophorus, an aggressive annual herb blamed for crop losses and human health problems, including contact dermatitis and respiratory irritation. Choosing one tree, one shrub and one herb was deliberate, because the spectral and phenological signatures of these life forms differ in ways that matter for remote sensing.

The technical backbone of the approach is the Normalized Difference Vegetation Index, or NDVI, a measure derived from the way vegetation reflects red and near-infrared light. Healthy, photosynthetically active foliage reflects near-infrared strongly and absorbs red light, producing a characteristic ratio that satellites can measure from orbit. Sentinel-2, a pair of twin satellites operated by the European Space Agency’s Copernicus programme, revisits every point on Earth roughly every five days and captures imagery at a resolution fine enough to resolve urban vegetation patches. Rather than relying on a single snapshot, the researchers assembled monthly NDVI time series, exploiting phenology, the seasonal rhythm of leafing, flowering and senescence, to separate invasive species from the surrounding green matrix.

That phenological logic is what makes the method clever. Invasive plants often green up earlier, hold their leaves longer or peak at different times than native vegetation, creating temporal fingerprints that a single-date image would miss. The team fed these monthly spectral metrics, alongside environmental and land-cover predictors, into MaxEnt, a maximum-entropy species distribution model widely used in ecology to estimate habitat suitability from presence-only records. MaxEnt compares the environmental conditions at known occurrence points against the background landscape and produces a continuous suitability surface. Crucially, the model also reports how much each predictor contributes to the final prediction, and here the monthly variables told a species-specific story. The contributions of different months varied among the three species, and this variation pointed to candidate surveillance windows concentrated in the late post-monsoon period and in late winter, the seasons when each invader’s spectral behaviour diverges most clearly from its surroundings.

A model is only as good as its validation, and this is where Google Street View entered the picture, a pairing that seems almost whimsical until you consider the economics. Street View offers panoramic, street-level imagery of entire cities without a single kilometre of walking. The researchers sampled 90 Street View locations per species and scored them for visible detection of each plant. The results tracked modelled suitability strikingly well: detections rose consistently from low to high suitability classes, and each step up in suitability class was associated with 3.46 to 4.11 times higher odds of detecting the target species. In statistical terms, the MaxEnt surfaces were not just plausible maps; they carried real predictive information about where a street-level observer would actually encounter these plants.

Ground truthing in the field added a second layer of confirmation. Surveyors visited 30 high-suitability sites per species and confirmed presence for 27 of 30 sites for Lantana camara, 26 of 30 for Neltuma juliflora and 24 of 30 for Parthenium hysterophorus. Those hit rates, between 80 and 90 percent, are exactly the kind of efficiency gain that matters for city agencies. Instead of searching blindly, field crews can be dispatched to locations where the model says they are most likely to succeed, effectively multiplying the return on every hour of survey effort. The study also revealed a human factor worth noting: agreement between independent observers was lower for the herbaceous Parthenium than for the two woody species, a reminder that small, low-growing plants are harder to spot consistently, whether through a car-mounted camera or from the roadside.

Land-cover overlays added ecological texture to the results. The woody invaders showed their highest mean suitability in forested land, consistent with their need for established canopy and soil conditions, while the herb Parthenium peaked in built-up areas, thriving in the disturbed, nutrient-poor waste ground that cities produce in abundance. This distinction matters for management strategy, because a shrub lurking at the forest edge and a weed colonising roadside verges require entirely different detection and removal tactics. The team went further by integrating Dynamic World, a near real-time, 10-metre-resolution global land-cover product developed by Google and the World Resources Institute. By intersecting the maximum-suitability screening layer with areas flagged as having low vegetation probability in Dynamic World, they identified potential conflict zones where urban development and invasive habitat overlap.

The scale of that overlap is striking. Across Lucknow, the analysis flagged 1,000.61 hectares as potential conflict zones, land where high modelled suitability for invasive plants meets low vegetation cover, the conditions under which urban greening investments are most likely to be undermined. Within the city’s formally mapped administrative wards, 361.37 hectares of such zones fall squarely inside areas where municipal management decisions apply. For a city planning new parks, avenue plantings or restoration schemes, those hectares represent a prioritised to-do list: places where the money spent on greening is most at risk of being swallowed by invaders that outcompete planted seedlings and degrade the ecological integrity of the finished project.

What elevates the study beyond a local case study is its cost profile. Every major input is free or nearly free: Sentinel-2 imagery through Copernicus, MaxEnt as open-source software, Google Earth Engine for planetary-scale computation, Dynamic World as a public dataset, and Street View as a pre-existing photographic archive. The workflow requires no drones, no hyperspectral aircraft campaigns and no proprietary analytics, only the technical capacity to run the models and the local botanical knowledge to interpret them. The authors note that with local recalibration, including species-specific occurrence records and phenological tuning to regional climate, the same framework could inform surveillance policies and the allocation of management resources in other cities with expanding urban greening programmes.

The implications reach into some of the thorniest debates in invasion ecology. Trees like Neltuma juliflora occupy contested territory because they deliver ecosystem services, such as shade and fuelwood, even as they displace native communities and alter soils. Surveillance tools that map where such species are spreading, rather than debating whether they are good or bad in the abstract, give city planners a way to manage the trade-off spatially. There is also a public-health dimension: Parthenium is a recognised allergenic weed, and its affinity for built-up land means that dense neighbourhoods may face disproportionate exposure. In an era when climate change is shifting phenologies and expanding the ranges of opportunistic species, the Lucknow study suggests that the most powerful early-warning systems may come not from expensive bespoke technology but from creatively combining the planetary data infrastructure that already exists, orbiting overhead and parked on the street corner alike.

Subject of Research: Resource-efficient surveillance of invasive plants using Sentinel-2 phenology-based habitat modelling and Google Street View validation in Lucknow, India

Article Title: Resource-efficient surveillance of invasive plants using Sentinel-2 phenology and street view validation

Article References: Singh, P. P., Shukla, U., Singh, S., Shipra, Samal, P., Mathur, A., Verma, P., Kaur, J., Behera, S. K., Rai, R., & Adhikari, D. (2026). Resource-efficient surveillance of invasive plants using Sentinel-2 phenology and street view validation. Environmental Monitoring and Assessment, 198(11), Article 1202. https://doi.org/10.1007/s10661-026-16063-w

Image Credits: AI Generated

DOI: 10.1007/s10661-026-16063-w

Keywords: invasive plants, Sentinel-2, NDVI, phenology, MaxEnt, Google Street View, urban greening, habitat suitability, Dynamic World, Lantana camara, Parthenium hysterophorus, Lucknow

The research, led by Shanshan Qi of Jiangsu University together with colleagues from institutions across China and Australia, focused on two notorious invasive plants: Bidens pilosa, commonly known as hairy beggarticks, and Sphagneticola trilobata, the creeping wedelia. Both species, native to the Americas, have spread aggressively across tropical and subtropical regions of Asia, where they frequently appear together in disturbed habitats. When two invasive species establish in the same location, ecologists call this co-invasion, and it can accelerate biodiversity loss far more severely than a single invader acting alone.

The team began with a field survey, examining naturally co-occurring populations of the two invaders to measure how heavily their roots were colonized by mycorrhizal fungi. These fungi form symbiotic partnerships with most land plants, threading into root tissues and extending networks of hyphae into the soil. In exchange for plant-derived carbon, the fungi deliver hard-to-obtain nutrients, particularly phosphorus, to their hosts. The survey produced a striking result: mycorrhizal colonization rates were significantly higher in communities where the two invaders grew together than in sites dominated by a single species. Something about coexistence appears to encourage the fungal partnership.

To untangle the mechanisms behind this pattern, the researchers moved into the greenhouse, where they could control the proportions of each species and the presence of AMF with precision. Their experimental design allowed them to measure not just growth, but the intensity of competition between and within the two invaders under different conditions. This is where the story became genuinely surprising, because the fungi’s influence proved anything but uniform.

The greenhouse results showed that the growth promotion induced by AMF decreased as the proportional abundance of an invader increased. In other words, when a species was rare within the mixture, the fungi gave it a substantial lift; when it dominated the pot, that benefit faded. This proportion-dependent response suggests that the value of the symbiosis is not a fixed trait of either plant species but a dynamic property of the community’s composition. A rare invader, perhaps freed from intense competition for fungal services, reaps outsized rewards from the partnership.

Even more intriguing was the effect on competition between the two species. AMF effectively alleviated interspecific competition, softening the struggle between Bidens pilosa and Sphagneticola trilobata when they grew side by side. However, this buffering effect weakened as competition intensified. When the two invaders were locked in a fierce contest for space and resources, the fungi could no longer smooth over the conflict. The symbiosis, it seems, acts as a moderator only up to a threshold of competitive pressure.

The picture inverted completely under monoculture conditions. When either species grew alone with members of its own kind, AMF exacerbated intraspecific competition, making life harder for plants competing against their own kind. This asymmetry, where fungi ease conflict between species while sharpening conflict within species, has profound implications for how co-invading populations structure themselves. It hints that the fungi may push communities toward mixtures rather than pure stands, subtly reshuffling the competitive balance in favor of coexistence between the invaders.

These findings connect to a broader and increasingly urgent body of research on invasional meltdown, the hypothesis that positive interactions among non-native species can accelerate their collective impact. Previous work has documented how soil microorganisms can mediate such meltdowns, with invasive plants sometimes cultivating fungal communities that favor themselves or other invaders over native species. The new study adds a crucial layer of nuance: the direction and strength of these microbial effects depend on proportional abundance, meaning the same fungal community could facilitate an invader at low density and constrain it at high density. Ecologists have long recognized that density dependence shapes plant populations, but demonstrating that mycorrhizal fungi modulate both interspecific and intraspecific competition in a proportion-dependent way is a significant advance.

The technical implications extend to invasion management. Control strategies that target a single invader may inadvertently create conditions in which the remaining invader, now at lower proportional abundance, receives a stronger mycorrhizal boost and rebounds aggressively. Conversely, understanding that AMF intensify intraspecific competition in monocultures suggests that dense, single-species invasions may harbor their own internal brakes, ones that could potentially be leveraged in restoration efforts. The authors note that their work reveals a complex, density-dependent role for AMF in modulating competition between co-occurring invaders, and that the fungi can shift the competitive balance depending on plant proportional abundance.

As biological invasions continue to impose mounting economic and ecological costs worldwide, studies like this one underscore that the battle against invasive species is not fought only above ground. The hidden fungal networks threading through the soil are active participants, capable of amplifying or dampening the fortunes of co-invading plants in ways that shift with every change in community composition. For land managers and restoration ecologists, the message is clear: to predict which invader will prevail, and when, they must look below the surface and account for the proportional arithmetic of the invasion itself.

Subject of Research: Density-dependent effects of arbuscular mycorrhizal fungi on competition between co-invading plant species

Article Title: Proportion-dependent asymmetric facilitation of co-invaders by arbuscular mycorrhizal fungi

Article References: Qi, S., Chen, R., Lei, P., Shu, Z., Zhai, D., Ren, G., Wang, H., Yan, X., Dai, Z., Du, D., & Bonser, S. P. (2026). Proportion-dependent asymmetric facilitation of co-invaders by arbuscular mycorrhizal fungi. Plant and Soil. https://doi.org/10.1007/s11104-026-09045-x

Image Credits: AI Generated

DOI: 10.1007/s11104-026-09045-x

Keywords: arbuscular mycorrhizal fungi, co-invasion, Bidens pilosa, Sphagneticola trilobata, plant competition, invasional meltdown, density dependence, soil microbiome, invasive plants, symbiosis, plant ecology, biodiversity loss

The headline result is striking. The material achieved a maximum fluoride adsorption capacity of 469.64 milligrams per gram, outperforming the magnesium oxide based adsorbents compared in the study. To put that figure in perspective, adsorption capacities in the tens of milligrams per gram are often considered respectable for fluoride removal, so a material approaching the 470 milligram per gram mark represents a substantial leap in performance. The researchers attribute this capacity to the intimate coupling of two components: a porous, plant-derived carbon scaffold and nanostructured magnesium oxide particles dispersed across its surface.

The synthesis route is deliberately simple, which matters enormously for any technology hoping to move from the laboratory bench to real treatment systems. The team first converted Rhus typhina biomass into hydrochar through hydrothermal carbonization, a process in which wet biomass is heated in water under pressure, producing a carbon-rich solid. This hydrochar was then subjected to pyrolysis in the presence of magnesium, yielding the final composite. The two-step pyro-hydro approach leaves behind a porous carbon architecture whose internal channels and cavities serve a dual purpose: they physically separate and stabilize the nano-MgO particles, preventing them from clumping together and losing reactive surface area, and they provide an enormous internal surface where fluoride ions can make contact with active sites.

Corresponding author Jiunian Guan framed the work as a deliberate double win. According to the research team, the goal was to address two environmental challenges simultaneously: fluoride contamination in water and the growing accumulation of invasive plant biomass. By converting the biomass into a functional carbon material and combining it with nano-magnesium oxide, the researchers created an adsorbent with strong fluoride-removal performance and promising environmental adaptability. That framing reflects a growing trend in environmental materials science, in which waste streams of one problem become feedstocks for solving another, closing loops rather than simply displacing pollution from one place to another.

The case for better fluoride treatment is urgent. Fluoride occurs naturally in groundwater, particularly in regions where fluoride-bearing minerals weather into aquifers, but human industry adds substantially to the load. Semiconductor manufacturing, glass production, electroplating, lithium refining, pesticide production, and pharmaceutical manufacturing all generate fluoride-containing wastewater. While trace fluoride strengthens tooth enamel and is deliberately added to municipal water in some countries, chronic exposure to elevated concentrations can cause dental fluorosis and, at higher doses, skeletal fluorosis, a painful and debilitating condition. Effective, affordable defluoridation technologies are therefore critical both for protecting drinking water supplies and for helping industry meet discharge standards.

One of the most practically important findings of the study is the material’s robustness across chemically diverse waters. Real wastewater is never clean; it carries a cocktail of dissolved salts whose ions compete with fluoride for adsorption sites. The nMgO/Py-HyC composite maintained stable fluoride adsorption across a broad pH range from 5.0 to 11.0, spanning acidic to strongly alkaline conditions. That breadth is unusual and valuable, because many adsorbents perform well only in a narrow pH window, forcing operators to add chemicals to precondition the water. Common coexisting ions such as nitrate and sulfate caused little interference with fluoride uptake, although the researchers did note that high concentrations of bicarbonate reduced adsorption, a limitation that will need to be considered when treating alkaline, bicarbonate-rich groundwaters.

Detailed material analyses revealed that fluoride capture is not the work of a single mechanism but a coordinated ensemble of processes operating in parallel. The identified mechanisms include electrostatic attraction, in which positively charged surface sites draw in the negatively charged fluoride ions; surface complexation, in which fluoride binds directly to magnesium centers at the surface; anion and ligand exchange, in which fluoride swaps places with hydroxyl groups or other ligands bound to the magnesium oxide; precipitation, in which dissolved fluoride reacts to form solid phases; and hydrogen bonding, which provides additional weak but numerous interactions. Spectroscopic and compositional evidence showed that fluoride could interact directly with magnesium to form stable compounds, including magnesium fluoride, known as MgF2, and fluorine-containing magnesium hydroxide phases. The involvement of precipitation and the formation of thermodynamically stable products is particularly significant, because it suggests that captured fluoride is locked in place rather than merely held loosely and at risk of leaching back out.

Perhaps the most scientifically elegant observation is the synergistic effect between the carbon support and the nano-magnesium oxide. Under identical experimental conditions, the adsorption capacity of the combined material was substantially greater than the sum of what the two components achieved separately. The porous carbon framework does more than passively hold the magnesium oxide; it exposes active magnesium sites that would otherwise be buried, improves the contact between fluoride ions in solution and those reactive sites, and may facilitate mass transport through its interconnected pore network. In materials chemistry, this kind of synergy, where the whole outperforms the parts, is the hallmark of a well-designed composite, and it is precisely what separates an engineered adsorbent from a simple mixture of ingredients.

Beyond the laboratory numbers, the study sketches out a circular strategy with genuine ecological appeal. Rhus typhina, commonly known as staghorn sumac, is an aggressive invader in many temperate regions, forming dense stands that displace native vegetation and require costly mechanical control. Harvesting its biomass and converting it into a high-value water treatment material transforms an ecological management burden into a resource, offsetting remediation costs while simultaneously cleaning contaminated water. If the supply chain can be organized, invasive plant management programs and water utilities could become unlikely partners, with the byproducts of habitat restoration feeding directly into drinking water protection.

The authors are appropriately measured about what remains to be done. Further work is needed to evaluate the material under different real-world wastewater conditions and at engineering scale, where factors such as column hydraulics, regeneration cycles, spent-adsorbent disposal, and long-term cost all come into play. A laboratory batch capacity of nearly 470 milligrams per gram must survive contact with turbid, variable, and chemically complex waters before it can be called a technology. Still, the findings provide a promising foundation for developing high-efficiency, low-carbon fluoride treatment technologies based on renewable biomass resources. In a field where adsorbents are often criticized as laboratory curiosities that never scale, a material that is cheap to make, works across a wide pH range, resists interference from common ions, and is built from an invasive species that needs removing anyway has an unusually credible path forward. The study, published in Biochar X with the DOI 10.48130/bchax-0026-0021, offers a template for how environmental chemistry, materials engineering, and invasive species management can converge on problems that no single discipline can solve alone.

Subject of Research: Nano-magnesium oxide modified pyro-hydrochar derived from invasive plant biomass for fluoride adsorption from water

Article Title: Turning invasive plants into powerful filters for fluoride-contaminated water

Article References: Turning invasive plants into powerful filters for fluoride-contaminated water. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: fluoride removal, adsorption, biochar, pyro-hydrochar, nano-magnesium oxide, Rhus typhina, invasive plants, water treatment, hydrochar, groundwater contamination, biomass utilization, environmental remediation