The distylous plant Primula veris has long served as a model species for studying heterostyly, that is the occurrence of multiple floral morphs within a population to ensure outcrossing. Habitat loss, reduced plant population sizes, and climate change have raised concerns about the impact of these factors on morph ratios and the related consequences on fitness of heterostylous species. We studied the deviation of floral morphs of P. veris from isoplethy (i.e. equal frequency) in response to plant population size, landscape context and climatic factors, based on a pan-European citizen science campaign involving observations from 28 countries. In addition, we examined the relative frequency of morphs to determine whether landscape and climatic factors disrupt morph frequencies or whether a specific morph has an advantage over the other. Theory predicts equal frequencies of short-styled S-morphs and long-styled L-morphs in populations at equilibrium. However, data from >3000 populations showed a substantial morph deviation from isoplethy and a significant excess of S-morphs (9% higher compared to L-morphs). Deviation of morph frequency from equilibrium was substantially stronger in smaller populations and was not affected by morph identity. Higher summer precipitation and land use intensity were associated with an increased prevalence of S-morphs. Five populations containing individuals exhibiting short homostyle phenotypes (with the style and anthers in low positions) were found. Genotyping of the individuals at CYP734A50 gene of the S locus, which determines the length of the style and the position of anthers of P. veris, revealed no mutations in this region. Our results based on an unprecedented geographic sampling suggest that changes in land use and climate may be responsible for non-equilibrium morph frequencies. This large-scale citizen science initiative sets foundations for future studies to clarify whether the unexpected excess of S-morphs is due to partial intra-morph compatibility, disruption of heterostyly or survival advantage of S-morphs. Synthesis. Human-induced environmental change may affect biodiversity indirectly through altering reproductive traits, which can also lead to reduced fitness and genetic diversity. Further research should consider the possible role of pollinators in mediating the ecological and evolutionary consequences of recent landscape and climatic shifts on plant reproductive traits.

1. Delayed biodiversity responses to environmental changes occur from genes over communities to ecosystem functions. Despite growing insights into the mechanisms governing both the magnitude and time lags of biodiversity responses at individual levels of biodiversity, how interactions among levels of biodiversity affect ecosystem-wide inertia in response to an environmental forcing event remains a largely unanswered question.
2. As several sources causing time lags interact within and across multiple biodiversity levels, we hypothesise these mechanisms control how time lags at one biodiversity level may cascade into increasingly extended lags at higher biodiversity levels.
3. We analysed empirical data on genetic diversity, species distributions, community diversity and functional diversity in semi-natural grassland patches for the existence and length of lagged responses across biodiversity levels in response to 165 years of land-use change.
4. Time lags were present at all tested biodiversity levels (from genes to traits), none yet in equilibrium with the current landscape. Significant variation in delays among individual species possibly controlled by delayed loss in genetic diversity may affect the scale of future biodiversity losses at the community level.
5. Functional diversity appeared to have the most delayed response, likely due to high functional redundancy in species-rich grassland communities.
6. Synthesis. Species identity seems central in governing the observed delays at each level of biodiversity, from genetic to functional diversity. In particular, species identity controls the slowest responses at the genetic level, potentially leading to accumulating underestimations of the size and duration of time lags at species, community and functional diversity levels compared to average community responses. Conservation and restoration actions must therefore anticipate the potentially systematic underestimation of time lags in biodiversity responses following habitat change to ensure their effectiveness in halting biodiversity loss.

1. Volunteers have been involved in nature observations for decades through citizen science initiatives, providing large data sets as well as problem identification that allow a more complete understanding of many natural phenomena. Although communication is a core component in citizen science, the key factors that determine its effectiveness in national and transboundary campaigns aimed at broad audiences have remained unclear.
2. Using the pan-European citizen science campaign ‘Looking for Cowslips’ spanning across 31 European countries as an example, we explored the main communication facilitators and barriers campaign organisers face in different European regions when engaging the public in citizen science. To do so, we conducted interviews, questionnaires and discussion groups with the campaign organisers.
3. The results indicate that communication in citizen science initiatives poses a challenge, particularly for researchers, who often do not have sufficient time or means for the necessary engagement and communication efforts. In addition to the ecological characteristics of the focal species in the different regions of Europe, the key aspects that need to be considered for planning effective communication in transboundary citizen science projects include various socio-cultural factors, such as the traditions related to citizen science in different countries as well as local indigenous knowledge.
4. Our study shows that collaboration between academic institutions and environmental non-governmental organisations, but also the contribution by local co-organisers at the national level, is crucial for the effectiveness of international citizen science campaigns. In addition, facilitators and barriers of communication need to be considered in each region separately as even at the European scale, we observed a high variability of environmental and socio-cultural settings.
5. Synthesis. In an era of detrimental consequences of human activities on natural ecosystems, it is vital to include society in observations to determine the impact of environmental change on biodiversity through citizen science approaches. Substantial advances in technological tools have helped to foster these initiatives across vast spatial scales. Nevertheless, it is also crucial to select the right pathways for communication to compete with vast amounts of other information and to reach potential participants in varying socio-cultural contexts of different countries.

Most insect pollinators are ectothermic and rely on external heat sources for temperature regulation. Forests, with their diverse canopy structures and sunlight penetration levels, create a mosaic of microclimates influencing these insects' behaviour. This study examined how macro- and microclimatic temperatures, precipitation, forest structure, and flower resources affect pollinator activity in the understory of two Swedish mixed forests using a combination of artificial flower stations, time-lapse pictures, and high-resolution climate data. Diptera was the most abundant order of flower visitors, with Muscidae, Phoridae and Syrphidae being the most recorded families. Our results show that macroclimate was the main driver of flower visitation rates, while microclimatic conditions better predicted foraging time. Based on our models, forest fly pollinators increase their flower visitation rates within a narrow temperature window. Thus, we anticipate that the effects of rising temperatures due to climate change on flower visitation rates by insects will largely depend on baseline temperature. Additionally, temperature appears more important than changes in other macroclimatic variables such as rain. Precipitation reduced pollinator visits, and pollinators increased their activity with time since the last rainfall. Forest density negatively impacted pollinator presence, with effects varying by pollinator group and species, but suggesting that increasing canopy openness could enhance pollinator habitats and support biodiversity. Higher flower species richness decreased visitation rates but extended pollinator foraging time in some cases. Conversely, abundant wildflowers increased pollinator visitation rates but reduced their overall foraging time, probably due to competition. Our study highlights the complex relationships that occur between forest structure, climate, flower resources, and pollinator activity. Understanding species-specific responses to forest composition and understory vegetation can guide tree species selection in afforestation or reforestation projects to support diverse pollinator communities, ultimately informing effective conservation and forest management practices to maintain healthy pollinator populations and ecosystem resilience under a changing climate.

1. Habitat loss and nutrient enrichment are major drivers of plant species declines. However, local extinction risks vary widely and are shaped by life-history trait syndromes. Genomic life-history traits, which are simple, stable and widely available, offer a promising yet underexplored approach to improving extinction risk assessments and informing conservation efforts.
2. Using a spatial comparison approach, we analysed 256 semi-natural grassland plant communities in four Swedish agricultural landscapes to examine whether genomic life-history traits such as ploidy, genome size and chromosome number mediate differences in plant community diversity and composition along independent gradients of grassland fragment size and phosphorus availability.
3. Our findings show that plant diversity and community composition are increasingly dominated by larger genome species both as grassland fragments become smaller and as more phosphorus becomes available. While all genomic life-history traits proved important, ploidy plays a particularly significant role in explaining differences between observed plant communities.
4. Ploidy mediated deterministic plant community changes along both environmental gradients. Diploid species are especially vulnerable to local extinction, whereas polyploids demonstrate resilience to habitat loss and benefit from increased phosphorus availability, likely leading to the competitive exclusion of diploids.
5. Synthesis. By revealing how genomic traits shape plant community responses to land-use change and nutrient pollution—two key drivers of extinction—our study introduces a predictive, genomic trait-based framework for assessing local extinction risks in fragmented landscapes.

Introduction: The recovery of habitats following restoration requires that suitable environmental conditions, propagule sources, and adequate active management all co-occur. Identifying the extent to which these different factors co-exist can support post-restoration actions and pinpoint possible locations for colonization by plant species at a landscape scale. We studied a 400 ha landscape undergoing restoration to identify the suitable habitats for the establishment of grassland communities. Methods: We combined environmental data for variables which are key for plant species occurrence (vegetation structure, soil moisture, slope range, cover of bedrock) with observational layers of connectivity (proximity to propagule source and livestock activity by using global positioning system collars in the landscape) to classify restored sites according to their potential to support establishment of grassland patches. Using 320 plant inventory plots (1 × 1 m) distributed over the area, we tested the relationship between suitability values from models and aspects of plant community composition. Results: We found that plant community composition was best explained by the interactions between environmental conditions and the location of propagule source and livestock activity. Greater proximity to propagule sources and the activity of grazing animals increased the likelihood for grassland species to colonize. Conclusions: Applying suitability maps by using spatial layers in restoration efforts can be a useful tool for locating candidate sites and planning post-restoration management actions. It would allow prioritizing certain locations where restoration could be most effective, for instance by steering the grazing regime to enhance colonization of target species.

Aims: Baltic coastal meadows host unique plant communities that are threatened extensively by environmental change. We re-inventoried the occurrence of Baltic coastal meadow plant specialists after 60 years to examine their response to habitat loss and management continuity and assess large-scale shifts in Baltic coastal meadows plant communities. Ultimately, we aimed to understand what defines losing and winning species in Baltic coastal meadows after 60 years of environmental change.

Location: Swedish Baltic coast.

Methods: In 2024, we re-inventoried 65 Baltic coastal meadows that were originally inventoried in the 1960s, assessing the abundance of eight specialist plant species. We used aerial image interpretation to map all coastal meadows in the region in both time steps, estimating local and landscape-scale habitat extent for the focal meadows. We also determined management continuity in these meadows using all available imagery in between the 1960s and 2024. We explored how management continuity and local and landscape-scale changes in habitat extent affect specialist species occurrence and local extinctions.

Results: Coastal meadow habitat extent across the whole region has decreased by 21% and only 57% of the meadows inventoried in the 1960s are managed today. Six plant species have decreased significantly, of which two were not found at all in 2024. Three species have remained stable in continuously managed meadows, whereas five species have decreased despite continuous management. There were no significant relationships between habitat loss, at either local or landscape scale, and extinction/persistence patterns.

Conclusions: Coastal meadows have disappeared or become smaller in size over 60 years, and our results indicate an extinction debt already in the 1960s due to habitat loss before the original inventory. Baltic coastal meadows are under cross-fire by many drivers of environmental change, likely augmenting biodiversity loss through synergetic interactions. Management continuity is imperative for population persistence, and urgent large-scale restorations are needed to reverse negative biodiversity trends.

Historical land-use changes shape present-day biodiversity through legacy effects, but the duration and mechanisms of these legacies are poorly understood. We used historical land-use maps in two Swedish landscapes across three centuries to examine the persistent influence of historical land use on plant and soil microbial communities. Overall, bacteria showed stronger legacy effects than fungi, but effects varied across functional groups of plant-associated and free-living taxa. However, soil-borne plant pathogenic fungi showed a persisting influence of arable land use which gradually disappeared after ~150 years, suggesting that land-use legacies decay over time. This dilution could relate to changing plant communities but also to changes in microbial associations, as suggested by species co-occurrence patterns over time. Our findings provide novel and crucial information on the duration of land-use legacies and single out soil-borne plant pathogens as key indicator groups of historical land use in present-day ecosystems.

Land cover data are commonly used to model the terrestrial carbon (C) sink, yet these data have wide margins of error that significantly alter estimates of global C storage. Here we demonstrate this data vulnerability in grasslands, which are critical to C cycling but whose estimated distribution has varied by >50 million km2 (3.5–42% of the Earth’s terrestrial surface). Comparing multiple high-resolution land cover products with expertly annotated grassland data from six continents, we show sources of mapping error and discuss C implications based on 2023 United Nations (UN) FAO estimates. Past misidentification arose from inconsistent definitions on grassland identity and classification flaws especially relating to woody plant cover. Correcting these errors adjusted grassland coverage to 22.8% of the terrestrial land base (30.1 million km2), elevating UN projections of soil C stocks to 155.02 Pg (0–30 cm depth). These findings underscore the challenges of biome mapping for ecosystem accounting and policy, when lacking field-validated remotely sensed data.

Large solitary trees (LSTs) represent important wood volumes and carbon stocks outside forests. However, quantification remains difficult as most allometric relationships have been developed using trees in forests. Here, we explore the volumetric assessment of aboveground woody biomass of LSTs outside forests and compare them to forest trees. Using terrestrial laser scanning, we captured detailed 3D point clouds of 215 solitary trees for three widely distributed species, i.e. Quercus robur, Tilia sp. & Fraxinus excelsior, across nine cities in temperate Europe. Leaf-off lidar point clouds were processed using a quantitative structure model (QSM) to estimate the aboveground volumes and develop new species-specific allometric volume equations for solitary trees. Our findings show that the woody volumes of LSTs estimated by QSMs are, on average, 83 % higher than those predicted by species-specific allometric equations tailored to forest trees of similar height and diameter at breast height. To validate this discrepancy, we applied the same laser scanning and modeling methods to both LSTs and forest trees. Regression analysis confirmed that LSTs have significantly greater woody volumes than forest trees. However, this difference diminishes with increasing height, resulting in converging volumes in the tallest height class. Our results highlight the substantial carbon storage and wood volume potential of LSTs in both urban and rural areas, and underpin the urgent need for dedicated allometric volume equations tailored specifically to large solitary trees.