Basic and Applied Ecology

Mediterranean mountain grasslands are ecosystems of high ecological and economic value. They are shaped by the dry and warm climate and land use, such as grazing, although the combined effects of both drivers remain poorly understood. In this study, we analyzed shifts in functional composition in thirty-two plant communities in Mediterranean mountain grasslands of the Pindos Range (Greece) by measuring five plant functional traits related to resource acquisition in dominant plant species. We examined the adaptive value of each trait as well as community-level responses along a well-defined two-dimensional gradient of grazing intensity and aridity, using mixed models and functional diversity analyses, and tested whether individual species trait shifts are related to aridity and grazing intensity. At the community level, aridity decreased plant height and leaf area whereas grazing only affected traits associated with tissue recovery such as high specific leaf area (SLA) and low community-weighted mean leaf dry matter content (LDMC). As aridity increased, plant height functional dispersion decreased. This convergence pattern indicates a shift towards more similar growth forms under arid conditions. Species-specific analysis indicated various responses of traits to the interaction of aridity and grazing that could not be detected using only community-level patterns. Overall, our findings demonstrate that aridity and grazing act through separate functional axes at the community level, while their combined effects emerge through species-specific trait plasticity.

The notion of "pollinator diversity" is central to most research and interpretations in animal pollination ecology. Nevertheless, when the term "diversity" is applied to pollinators its usage is often closer to the vernacular meaning (variety of kinds) than to concepts rooted in the "ecological diversity" tradition of community and statistical ecology. This paper attempts to fill a conspicuous knowledge gap in pollination ecology by presenting a comprehensive analysis of patterns of species abundance and diversity in a hyperdiverse insect pollinator assemblage from well-preserved Mediterranean montane habitats of southeastern Spain. Data on pollinator visitation to flowers of the community of entomophilous plants (288 species) were gathered over a 29-year period, and [~]95% of the pollinator individuals recorded were identified to species, totalling 46,401 individuals in 845 species. The shape of species abundance distributions (SADs) was virtually identical at regional (N = 56 sites) and local (one intensively studied site) scales, and SADs were best predicted by the log-series distribution. Pollinator diversity estimates corresponding to the first three Hill numbers (Species richness, Shannon diversity and Simpson diversity; 0D, 1D and 2D, respectively) were obtained for each plant species x site x year combinations ("sampling occasions", N = 472). Pollinator diversity measures varied widely among plant species; their frequency distributions were continuous, unimodal and strongly right-skewed; and variation was related to plant phylogeny, floral features (open vs. restrictive perianth, single flower vs. flower packet), and pollinator visitation to flowers and flowering patches. Pollinator diversity of individual plant species depended on habitat type, with those from dolomitic outcrops, rock cliffs and forest interior having the least diverse pollinators. 0D, 1D and 2D tended to vary independently of each other among habitats and years, revealing a complex spatio-temporal patterning of pollinator species richness and dominance. Estimated proportions of undetected pollinator diversity ("dark diversity") depended on insect order (highest for Diptera) and diversity measure (highest for 0D). Adoption of community ecology tools (SAD, sampling adequacy estimation, complementary diversity measures) to assess pollinator diversity will improve our ability to elucidate pollinator responses to natural and anthropogenic environmental change and permit hitherto unexplored questions in pollination ecology. "The ecologist sees in any measure of diversity an expression of the possibilities of constructing feedback systems or any sort of links, in a given assemblage of species" Margalef (1968, p. 19).

Biomass and surface area allocation affect resource uptake and carbon (C) residence time in forests, but the influence of tree diversity on allocation remains poorly understood. Moreover, mycorrhizal associations can alter this relationship, which has been rarely tested in mature forests. We investigated the role of both the proportion of ectomycorrhizal (ECM) trees and tree diversity on tree biomass and surface area allocation across a dual gradient of tree diversity (0 - 1.68 Shannon diversity) and ECM dominance (0 - 100 %) in a mixed deciduous forest area in Central Germany. We found that the two gradients affected tree biomass and surface area differently and mostly independently. Tree diversity had no significant effect on biomass or surface area in the investigated forest area, but increased the spatial variability of the leaf area index (LAI) from 21 % to 40 %. In contrast, a higher proportion of ECM trees was associated with an increase in fruit biomass (from 10 to 141 g m-2) and LAI (from 4 to 7 m2 m-2). Although tree diversity and the portion of ECM produced similar parsimonious models for explaining belowground biomass and surface area, neither showed a significant direct effect. Notably, their interaction enhanced the spatial variability of fine root biomass and root surface area; that is, forests with high diversity and a greater proportion of ECM trees exhibited a more heterogeneous distribution of fine roots. Allocation to fine root biomass appeared independent of tree diversity and the proportion of ECM trees, being influenced primarily by stand structure, with higher allocations observed in stands with lower stem basal area. We conclude that biomass allocation in this Central European Forest, where resource availability is relatively uniform, is primarily productivity-driven. A comparison of the biotic influences shows that ECM trees have a stronger control on aboveground surface area and fruit biomass than tree diversity, which may contribute to the ability of dominant ECM trees, such as European beech, to outcompete light competitors, but also puts temperate ECM forests at risk of physiological failures in increasingly drier future conditions.

O_LIThe global decline of natural forests is accompanied by a rapid expansion of commercial tree plantations, which are expected to further increase to meet growing demand for wood products. However, planted forests generally support lower biodiversity than natural forests, particularly when monospecific and intensively managed. In this context, broadleaved hedgerows have been proposed as a nature-based solution to enhance biodiversity within conifer-dominated plantation landscapes. Such features may be especially beneficial for small mammals, including rodents and shrews, which are key contributors to forest ecosystem functioning. However, their effects on small mammal communities remain largely unquantified. C_LIO_LIHere, we assessed variation in small mammal communities among habitat types within a native pine plantation-dominated landscape in southwestern France. Using a multi-year, multi-season survey, we compared species richness and abundance among plantation edges, broadleaved hedgerows embedded within plantations and natural broadleaved forests. We further tested whether environmental descriptors of hedgerow sites influenced dominant species and whether seasonal and interannual demographic dynamics modified habitat-related patterns. C_LIO_LIPine plantation edges and broadleaved hedgerows supported lower small mammal species richness than natural broadleaved forests and were dominated by two habitat generalists, Apodemus sylvaticus and Crocidura russula. This pattern was driven by the near absence of the forest specialist Clethrionomys glareolus. Hedgerows did not increase species richness relative to plantations, but provided favourable habitat for A. sylvaticus, which was scarce in pine plantation, while supporting fewer C. russula. Variation in hedgerow structure and composition further influenced A. sylvaticus abundance, while seasonal and interannual rodent population dynamics modulated habitat-related differences. C_LIO_LIOur results indicate that intensively managed pine plantations act as environmental filters, excluding forest-associated small mammals. While broadleaved hedgerows benefited one species, their capacity to restore forest-specialist communities was limited without broader landscape-scale interventions. These findings highlight both the ecological benefits and constraints of edge-based habitat interventions and provide guidance for designing and evaluating biodiversity-oriented management in plantation landscapes. C_LI

BackgroundPlants are exposed to various environmental challenges. With ongoing climate change, droughts and insect outbreaks are expected to become more frequent. Thus, a better understanding is needed of how different plant species respond to such single and combined challenges. This study investigated common versus species-specific responses to environmental challenges in three perennial plant species of different growth forms and whether responses differ intraspecifically among accessions. Clones of different accessions of the herbaceous species Tanacetum vulgare, the woody vine Solanum dulcamara, and the tree Populus nigra were subjected to similar control, herbivory, drought, and combined (drought and herbivory) treatments for the same periods. After the exposure, concentrations of foliar phytohormones and various morphological traits were measured. ResultsAcross all species, several foliar phytohormones and one of ten morphological traits responded consistently to the environmental challenges. Jasmonoyl-isoleucine was induced by herbivory and the combined treatment, abscisic acid (ABA) by drought and the combined treatment, and indole acetic acid by the combined treatment in all species. Root mass remained unchanged in all species. However, structural equation models (SEMs) revealed a shared regulatory pathway across species in which ABA connected treatment and root mass, indicating a common hormonal response potentially linking challenges to growth responses. Despite these common patterns, species-specific responses were pronounced. In P. nigra, a unique induction of salicylic acid was found under the combined treatment, while aboveground mass and root-shoot ratio remained unaffected by any treatment, in contrast to the other two species. Species-specific SEMs further indicated distinct phytohormone-mediated pathways underlying morphological variation. Phenotypic plasticity reflected these species-specific patterns, with none of the phytohormones or morphological traits exhibiting uniform plasticity across species. Intraspecific variation further shaped responses, as phytohormone and morphological trait plasticity depended on accession, indicating substantial accession-specific plant responses. ConclusionsOur results indicate that some responses to comparable challenges may be conserved across species, while others are species-specific. The combined treatment elicited the most pronounced responses, and such complex responses may become more frequent under current global change. Our study highlights that comprehensive understanding of plant responses requires systematic comparisons at both interspecific and intraspecific scales.

The effects of the selection of livestock type (e.g., sheep or cattle) and grazing intensity on the soil seed bank of sand grasslands of conservation interest were studied. 25 grazed grassland sites classified into four grazing intensity categories were studied. The soil seed bank was analysed by seedling emergence; germinated seedlings were classified into morpho-functional, social behaviour type (SBT) and CSR strategy groups. The following hypotheses were tested: i) Diversity and density of soil seed banks are lower in sheep-grazed sites than in cattle-grazed ones. ii) The species composition, diversity, and density of the soil seed banks are more strongly affected by grazing intensity than by the livestock type. iii) Leaf traits, SBT and CSR strategy composition are highly affected both by livestock type and grazing intensity. The main effect of livestock type only affected seed bank density, while that of grazing intensity had a significant effect on most of the variables. Most of the studied variables were affected by the interaction of grazing intensity and livestock type. Total seed bank density was lower at all grazing intensity levels in sheep-grazed sites than in cattle-grazed ones, especially close to frequently visited places. We found that sheep grazing sustained a much lower total seed bank density and lower density of species of natural and semi-natural habitats regardless to the grazing intensity. Thus, livestock type must be carefully selected and high-intensity sheep grazing should be avoided in the long-run when managing sand grasslands. HighlightsO_LIThe soil seed banks of sheep and cattle grazed sand grassland were studied C_LIO_LIEffect of grazing intensity found the most important driver of seed bank diversity and density C_LIO_LIThe total soil seed bank density was higher in cattle than sheep grazed sites C_LIO_LIBoth intensity and livestock type must be considered in the grassland management planning C_LIO_LIHigh intensity sheep grazing should be avoided in sand grassland management C_LI

AimTo examine how variation in frugivore species richness influences dietary specialisation and the organisation of plant-frugivore interaction networks in tropical forests. LocationSix undisturbed lowland wet tropical forest sites across four biodiversity hotspots in south and south-east Asia. Time period2016-2024. Major taxa studiedAvian frugivores and fleshy-fruited woody plants. MethodsWe recorded plant-avian frugivore interactions across six undisturbed evergreen forest sites spanning a seven-fold gradient in frugivore species richness, while holding forest type and phylogenetic composition broadly comparable. Using over 4,200 hours of focal observations on 551 fruiting plants, we recorded more than 34,000 feeding visits by 138 frugivore species on 133 plant species. We used a) Joint species distribution models to determine the relative influence of fruit and seed traits, and b) network analyses to evaluate how dietary breadth and network properties varied with frugivore species richness. ResultsAcross sites, frugivore visitation was primarily explained by fruit and seed morphology, with seed size accounting for an average of 39.7% of explained variation, followed by fruit width (24.4%), fruit crop size (21.9%), and pulp lipid content (14.1%). Frugivores in species-rich communities exhibited narrower dietary breadth (Pearsons r = -0.87 between normalised degree and species richness). Correspondingly, plant-frugivore networks became less connected and nested, and more modular, with increasing frugivore richness (Pearsons r = -0.9, -0.98, and 0.84, respectively). Main conclusionsIncreasing frugivore species richness intensifies dietary specialisation, which in turn drives changes in plant-frugivore network structure. These findings highlight how local species richness shapes interaction networks through changes in consumer niche breadth, with implications for the organisation of tropical forest mutualistic communities.

AimThe Global Biodiversity Information Facility (GBIF) is the most prominent source of species occurrence data for modeling climate niches, but exhibits strong unevenness in its data coverage across different geographic regions. The impact of this spatial bias on the reliability of GBIF-based plant climate niches in Europe remains unexplored. This study aims to address this gap, and to investigate whether the targeted integration of additional atlas data can reduce the potential impact of the spatial bias. LocationEurope. Time period1950s - 2024 Major taxa studiedEuropean grassland plant species. MethodsWe analyzed the climate niches of a large number of grassland species, with diverse distribution patterns across Europe, based on a) GBIF and b) on an enriched version of GBIF with national atlas data from Eastern European countries (GBIF+), where data coverage is currently low in GBIF. We followed best practices in niche characterization, particularly by performing environmental subsampling. The accuracy in climate niche properties was determined by comparing niches based on GBIF and GBIF+ data with niches based on a careful implementation of expert range maps as reference dataset. We focused on niche optimum position and niche similarity. Additionally, we investigated how biogeographical indicators can predict variability in climate niche accuracy. ResultsMost species exhibited reliable climate niche characterization using GBIF data, especially for widely distributed species. Yet, reliability decreased with continentality; that is, when species were primarily distributed in Eastern Europe. Integrating additional data did not significantly reduce this bias in niche characterization. Main conclusionsDespite the spatial bias in its records, GBIF can be used to reliably characterize the climate niches of many species in Europe if uneven sampling effort is accounted for. The laborious integration of additional data to address spatial bias does not yield the desired increase in niche reliability.

O_LITropical dry forests are among the most threatened ecosystems globally, yet the consequences of livestock overgrazing for ant communities remain poorly documented, particularly in the Tumbesian biodiversity hotspot of southwestern Ecuador, where uncontrolled goat grazing constitutes the dominant disturbance agent. C_LIO_LIWe sampled ant communities (Formicidae) across a goat-grazing disturbance gradient in Zapotillo (Loja Province, Ecuador), establishing three disturbance levels (Dense, Semi-dense, and Open Forest) with nine 60 x 60 m plots per level (n = 27) and 486 pitfall traps. Community responses were assessed using abundance-based and presence-absence analyses of morphospecies richness, Hill-number diversity, community composition, beta diversity decomposition, and functional guild structure; vegetation structure was characterized using satellite-derived NDVI. C_LIO_LIWe recorded 47,459 individuals belonging to 22 morphospecies in six subfamilies. Morphospecies richness declined with disturbance (Dense: 19, Semi-dense: 15, Open: 12), with four specialist genera exclusive to Dense Forest. Beta diversity decomposition revealed a shift from turnover-dominated dissimilarity at moderate disturbance to nestedness-dominated dissimilarity at high disturbance, indicating progressive habitat filtering as the dominant community-restructuring process. C_LIO_LICommunity composition differed among disturbance levels (PERMANOVA: F = 4.49, R{superscript 2} = 0.272, p = 0.001) and was correlated with NDVI (r{superscript 2} = 0.341, p = 0.013). Cryptic/soil and Leaf-cutter guilds were nearly eliminated from Open forest while the Opportunist guild expanded markedly, indicating that functional homogenization precedes detectable taxonomic impoverishment. C_LIO_LIOvergrazing drives directional ant diversity loss and biotic homogenization at both taxonomic and functional levels in the Tumbesian dry forest, underscoring the conservation value of intact Dense forest. C_LI

O_LIBiodiverse vegetation that supports high rates of ecosystem functions can inherently express a messy appearance due to high numbers of local native plant species and their spatial distribution connected to niche complementarity. This messiness is assumed to lower peoples appreciation for vegetation in urban contexts. Since such vegetation and a positive relationship between people and biodiversity could contribute to mitigating biodiversity loss, this assumed low public appreciation warrants investigation. C_LIO_LIWe designed and constructed biodiverse flowerbeds using only local native plants, and with the intention to enhance planting productivity, resistance and resilience. To investigate the influence of messiness, we created flowerbeds in four high levels of species richness (8,12,16,20) shown to be relevant for ecosystem functioning, and three levels of order (no, semi, full). We tested public appreciation for the flowerbeds using a self-guided, on-site survey. C_LIO_LIWe found a positive mean rating for all flowerbeds, but no effect of species richness on the ratings. Increased order, however, had a strong negative effect: The odds of a fully ordered flowerbed receiving a negative rating were 88% higher than of a flowerbed with no order. Increasing designed order was correlated with decreasing plant biomass in the flowerbeds. C_LIO_LIThese findings challenge the assumption that the appearance of biodiverse plantings is too messy for public appreciation in urban contexts. Specifically, we demonstrate that introducing order and reducing messiness can compromise aesthetic appreciation for biodiverse vegetation, potentially by compromising productivity as indicated by lower biomass production in ordered plantings. C_LI Synthesis and applicationOur study shows that biodiverse vegetation can be appreciated in urban contexts. Flowerbeds can effectively serve both people as ornamentation and biodiversity as habitat when they are designed based on ecological principles Research highlightsO_LIWe designed and realized flowerbeds based on ecological principles. C_LIO_LIAll plantings received positive average ratings. C_LIO_LIIncreasing species richness in the flowerbeds did not affect participants aesthetic appreciation. C_LIO_LIIncreasing order in the design of the flowerbeds strongly lowered participants aesthetic appreciation. C_LIO_LIIncreasing order in the design was correlated to lower biomass productivity and more bare soil in the flowerbeds. C_LI

Reduced competition or facilitation between kin relative to nonkin can improve plant performance, particularly under resource-limited conditions. Understanding whether kin interactions differ between invasive and native species may provide insights into the mechanisms underlying the persistence and spread of invasive species, particularly for species that spread clonally. To explore this, we conducted a greenhouse experiment using the invasive Alternanthera philoxeroides and its native congener A. sessilis in China. For both species, we grew central plants without or with neighbors, and for the latter we had three intraspecific neighbor kinship treatments (kin only, nonkin only, and both kin and nonkin [mixed] neighbors). To test whether kinship effects are affected by resource limitation, we grew the plants under two watering conditions (well-watered and drought-stressed). Our findings revealed that at both the group (i.e., pot-level) and individual levels, invasive plants had a higher biomass production and experienced a less negative relative neighbor effect in kin groups than in nonkin groups, while these patterns were reversed in the native species. Although aboveground architecture of central plants did not differ significantly between kin and nonkin neighbors in either species, neighbor plants of the invasive species produced fewer nodes in kin groups than in nonkin groups, while the reverse was true for the native species. These patterns were not affected by the watering treatment. Together, these results indicate that while the native plants has stronger kin competition, the invasive species has reduced kin competition. Such reduced competition among kin in the invasive Alternanthera philoxeroides may enhance its population dominance and facilitate its spread.

AimAs cities densify and expand, the careful planning and design of green spaces are essential for supporting urban biodiversity. Here, we evaluate the relative contribution of habitat patches of varying size, quality, and connectivity to urban biodiversity and assess environmental factors driving differences in species richness and community composition. LocationZurich, Switzerland. Time period: 2008-2018.Major taxa studied: Invertebrates, vertebrates, and trees. MethodsWe analyzed species occupancy data from 452 habitat patches. We quantified alpha, beta, and gamma diversity, assessed species-area relationships, and applied generalized dissimilarity modelling to test the role of patch area, connectivity, and habitat quality--proxied through environmental variables, including vegetation complexity, water presence, and forest isolation--in shaping community composition. ResultsAlpha diversity increased significantly with area, although small patches (usually < 5 ha) disproportionately contributed to beta diversity. Per unit area, groups of small patches yielded higher gamma diversity than equivalent areas of large patches, particularly for trees and invertebrates. Community composition was strongly influenced by patch area, with effects mediated by vegetation complexity, water, and isolation, with responses differing among taxa. Main conclusionsSmall habitat patches play a critical role in enhancing overall urban biodiversity. They increase species richness through cumulative area effects and promote community turnover (mediated by environmental heterogeneity). Maintaining networks of small patches alongside large green spaces is therefore key to conserving biodiversity in urban landscapes.

1) Differences in specialized metabolites are common both within and between plant species and are often thought to have regulating functions in ecological interactions, including herbivores like aphids. Although ants commonly rely on chemical cues in their behaviour and resource finding, very little is known about whether specialized plant chemistry regulates ant behaviour to foster successful ant-aphid mutualisms on plants and in the surrounding vegetation. 2) Using a chemodiversity experiment containing 84 plots with 6 chemotypes of Tansy (Tanacetum vulgare L. Asteraceae) planted in different proportions, i.e., plot-level chemotype richness, we tested the effects of plot-level chemotype richness, plot-level chemodiversity metrics, and individual chemotype presence on black garden ant (Lasius niger Linnaeus) nesting, patrolling and recruitment behaviour to plants and plots. Furthermore, we assessed the influence of plant chemotype on the pink tansy aphid (Metopeurum fuscoviride H.L.G. Stroyan) presence and abundance, as well as ant occurrence on Tansy plants. 3) We found that Tansy plot-level chemodiversity only minimally affected most of the observed ant behaviour, except for nesting, which was marginally positively impacted by plot-level chemotype richness. Clear effects of individual terpenoid chemotypes were observed on ant visitation rates, as well as on aphid presence and abundance. Strongly significant relationships between the probability of ant occurrence and aphid abundance and occurrence observed in our study suggest that ants and aphids are most strongly guided by the presence and abundance of their mutualist partners, rather than by specialized chemistry alone in the Tansy system.

Invasion-fire interactions can negatively impact ecosystems by driving biodiversity loss, altering ecological processes, modifying habitat structure, and compromising ecosystem functioning. Understanding how this interaction operates is essential to design effective management strategies that are successful in controlling both invasive alien species (IAS) and fire. Therefore, the present literature review aims to synthesize the current knowledge on invasion-fire interaction and its impacts on ecosystems, as well as identify knowledge gaps in the field. The review included 464 studies, from which information on context, species and fire characteristics, interaction outcomes, and research approaches was extracted. Fire generally promotes IAS, although studies on invasive animals are limited and no research has examined the effects of fire on fungi. Management through prescribed fire showed significantly better outcomes than wildfires in suppressing IAS, yet positive impacts still outnumbered the negative ones. In turn, IAS can change fire regimes causing regime shifts, but this direction of interaction is much less studied. Combined impacts of fire and IAS on ecosystems are predominantly negative, although interactions are complex and not always synergistic. Key knowledge gaps include geographic regions with known Invasion-fire interactions that remain underreported, a lack of broad-scale studies, limited management interventions, understudied taxa, and limited understanding of the combined effects on ecosystems. Remote sensing and laboratory experiments, which have been rarely used, could address some of these gaps.

By concentrating rodents along verges, roads can reshape rodent-mediated seed dispersal, yet empirical tests remain scarce. We conducted a two-year field experiment in Mediterranean oak woodlands in southern Portugal to test how seed dispersal varies with distance from roads across road type (paved vs. unpaved) and road-forest context (edge vs. non-edge). We tracked labeled holm oak acorns, recording dispersal distances and the number of dispersal events. The two metrics responded differently to road distance. Dispersal distances changed little with distance from roads in non-edge contexts but increased in edge road-forest contexts (2x longer at 400 m than at 10 m) and showed a year x distance-to-road interaction, with longer dispersal distances farther from roads in the second year (a poor mast year). Dispersal distances were also longer when acorns were deposited under shrubs and in areas of higher tree density, and decreased with greater natural acorn availability. In contrast, the number of dispersal events declined with distance from roads (30% more events at 10 m than at 400 m) and was higher along unpaved than paved roads (39% more events). Dispersal frequency also increased in the poor mast year and with shrub cover. No acorns crossed the road. Thus, road verges can concentrate rodent seed handling but do not increase dispersal distances near roads nor provide cross-road seed connectivity; instead, dispersal outcomes depend on edge context, road type, and microhabitat structure. Management that retains structural cover at verges and the adjacent forest edge (e.g., shrub patches and non-uniform clearing) can harness verge-associated activity to increase acorn deposition in sheltered microsites and promote regeneration farther into forest interiors in roaded landscapes.

European mountain forests have been strongly shaped by past human activities, which have influenced their structure and composition. Assessing the natural tree-species composition of current forest landscapes is essential for evaluating their biodiversity potential and for informing management prioritization. High levels of compositional naturalness are often associated with greater ecosystem functioning, but it remains unclear whether forest landscapes that are closer to their potential forest composition are also less vulnerable to future climate change and natural disturbances. Using a process-based forest landscape model, we quantified the naturalness and the vulnerability to disturbances across a large forested area in the Italian Alps. We developed a spatially-explicit index to evaluate how closely current tree species composition matches potential forest composition. We then simulated future forest dynamics under multiple climate change and disturbance scenarios, using two different initial vegetation conditions on the same landscape - potential vs. current forest - and compared their vulnerability based on changes in species dominance, vegetation structure, and height heterogeneity. Results indicate that current forests exhibit generally low naturalness compared with their potential forest composition, reflecting historical management and agro-silvopastoral practices. The naturalness score changed depending on elevation across the landscape: forests at low (<1500 m a.s.l.) and high (>2100 m a.s.l.) elevations had low naturalness, while those in the mid-elevation range (1500-2100 m) exhibited medium to high levels of naturalness. Vulnerability to disturbances under climate change differed markedly between the two initial vegetation conditions. Current forest was more susceptible to bark beetle outbreaks, driven by past promotion of Norway spruce and further amplified by warming. In contrast, the potential forest was more vulnerable to wind disturbance, likely due to old-growth characteristics, such as greater height heterogeneity and canopy roughness, that increase blowdown susceptibility. This study provides the first assessment of forest naturalness using spatially explicit dynamic landscape modelling. Given the projected intensification of natural disturbances under future climates, our findings suggest that promoting more natural forest conditions alone may not guarantee higher resilience to climate-induced disturbances. Instead, management approaches should aim at increasing landscape-level structural and compositional heterogeneity in a balanced manner to minimizing future disturbance vulnerability.

Urban green areas often harbour numerous non-native urban trees, many of which have characteristics that predispose them to escape from cultivation and become potentially invasive. Climate change is expected to exacerbate this risk by creating favourable conditions for species that are currently climatically restricted. The potential risks for invasiveness of urban tree species in continental Europe are not yet known. Here, we provide a comprehensive risk screening of 34 non-native urban tree species in continental Europe, for both current and projected future climate scenarios. Using the Terrestrial Plant Species Invasiveness Screening Kit (TPS-ISK v2.4), we assessed invasion risk based on biogeography, ecology, and projected responses to climate change. Results showed that under current conditions, 10 species (29.4%) were categorised as high risk, 23 (67.6%) as medium risk and one (2.9%) as low risk. The inclusion of climate change projections increased the number of high risk species to 11, with seven species categorised as very high risk. These taxa exhibit strong ecological plasticity, high reproductive performance and broad environmental tolerance, which together with projected warming, emphasises their significant potential for further spread. Our results emphasise the urgent need for early detection, continuous monitoring and proactive management of non-native urban trees in Europe, especially those that are widely used in horticulture and forestry. By integrating invasion biology with climate change risk screening, this study provides an important basis for evidence-based policy and management strategies to mitigate future ecological and economic impacts of invasions by urban trees.

BackgroundMicrobial communities in the rhizosphere are key drivers of plant immunity, mediating plant responses to stress. Under specific stresses plants are capable of recruiting beneficial microorganisms into their rhizosphere with the potential to alleviate these stresses. Among these stresses, herbivorous pests remain a major agricultural challenge. Despite this, the impact of leaf herbivory on root-associated microbiomes, and how this impact can shape plant defense phenotypes are still understudied. In this study, our main objective was to determine the extent to which leaf herbivory affects the rhizosphere microbiome, and whether and how these herbivory-induced changes modulate plant defense phenotypes through plant-soil feedback. To that end, we designed a two-phase assay in which we challenged sunflower (Helianthus annuus L.) with Spodoptera exigua and later tested the effect of the microbial legacy after infestation on sunflower defense phenotype, considering resistance and tolerance as major drivers. ResultsWe found that herbivory triggered significant changes in the bacteriome structure and dynamics, and microbiome functional profile, while effects on mycobiome were comparatively less pronounced. Under herbivory, several bacterial taxa and functional groups were enriched, the bacterial co-occurrence network was more complex and assembly processes were slightly more stochastic. Furthermore, after evaluating the plant-soil feedbacks of herbivory-induced microbiomes we observed no effect on plant resistance proxies such as herbivore growth and survival, and leaf phenolic and flavonoid content. We did observe differences on tolerance proxies, while plants grown on herbivore-challenged microbiome were overall smaller, the biomass loss to herbivory was significantly lower while the elemental nutrient content and photosynthetic pigments content was enhanced. ConclusionsOur study demonstrates that insect herbivory by S.exigua reshapes sunflower rhizosphere microbiome and generates a soil legacy that promotes herbivory tolerance on subsequent plant generations. This highlights the broader potential of microbiome-mediated plant-soil feedbacks in shaping plant adaptation to herbivory.

To adapt Mediterranean forests to increasingly harsh climatic conditions by promoting genetic diversity, thinning is often considered an effective strategy to enhance sexual regeneration. However, determining an optimal thinning level that both increases light availability and maintains favorable microclimatic conditions for germination, without excessively promoting herbaceous competition, remains challenging. To better understand how abiotic and biotic factors influence oak seedling development and to help identify a balanced thinning level under climate change, we conducted a semi-controlled experiment testing the combined effects of competition with a grass species (Poaceae), two canopy opening levels, and water stress. Our results highlight the crucial role of competition with Poaceae species - in our case Festuca ovina - in oak regeneration. Their presence not only intensifies competition for essential resources, but also modifies soil properties and alters belowground interactions, overall creating conditions less favorable for oak seedling establishment. In addition, our results highlight the significant impact of key abiotic factors that are canopy opening (which influences light availability) and hydric conditions, as well as their interactions with the effects of competition. We observed a consistent need for adequate light to ensure optimal seedling performance, suggesting that successful regeneration depends on balancing sufficient canopy opening to improve light availability with maintaining sufficient cover to mitigate water stress and limit grass competition. Overall, our study contributes to the broader debate on sustainable forest management strategies under changing climatic conditions.

Urban expansion drives land cover change and habitat simplification, contributing to biodiversity loss. Urban green spaces can mitigate these impacts, but their effectiveness depends on its configuration and implementation. Here, we examine how three complementary dimensions of environmental heterogeneity--plant species richness, habitat heterogeneity, and foliage-layer richness--shape bird richness along an urbanisation gradient in the Netherlands. Using bird and plant occurrence data, LiDAR-derived vegetation structure, and land-use data, we fitted generalized additive models at three spatial scales (100, 200, and 300 m) to assess how these relationships vary across the urbanisation gradient. Plant species richness showed the strongest and consistent positive effect on bird richness, disregarding urbanization intensities. Habitat heterogeneity showed most pronounced positive effects at intermediate levels of urbanisation. In contrast, foliage-layer richness had weak associations with bird richness across urbanization intensities. Together, these results demonstrate that sustaining urban bird diversity requires urbanisation-intensity-dependent design of green-space heterogeneity. Increasing plant richness is generally recommended across urbanization intensities. Increasing habitat heterogeneity is more effective at intermediate levels of urbanisation and appears less suitable in highly urbanised contexts. Beyond simply expanding green space area or their spatial complexity alone, urban planning should focus on the thoughtful design of different types of environmental heterogeneity. This includes city-wide species-rich planting and structurally diverse habitat mosaics in mid-density areas to sustain urban bird diversity.