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.

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.

1. Urban areas can support diverse communities of plants and animals. Yet, urbanisation can affect functionally important species traits, potentially impacting population dynamics.
2. The saproxylic beetle Elater ferrugineus L. is associated with large trees and is often used as an indicator of species-rich saproxylic communities. It is an important target for conservation and it is listed as a near-threatened species on the European Red List.
3. Few studies have quantified the impact of urbanisation on the ecology and intraspecific variation in functional traits of arthropods, other than pollinators.
4. We studied how the local abundance of E. ferrugineus and functionally important response traits (e.g., width of the pronotum, length of the elytron and wing, wing area, body mass and wingload) changed along urbanisation gradients in eight European cities using pheromone traps installed on large solitary trees.
5. We analysed the effects of the surrounding built-up area and tree cover on our response variables while accounting for potential confounding effects due to tree size and the availability of microhabitats.
6. Urbanisation had a strong negative effect on the local abundance of E. ferrugineus, while the amount of tree cover had a positive influence.
7. We found no significant impact of urbanisation on the functional traits of this species, except for a significantly higher wingload in city centres.
8. Our results provide a better understanding of the ecological processes impacting this saproxylic beetle and underpin the importance of future research on urbanisation's impact on arthropods.

Large solitary trees are keystone features for biodiversity in many urban and rural landscapes around the world. Yet, because of their isolation, they do not benefit from the buffering effect of neighbouring trees as in forests. As they are more exposed, solitary trees are more vulnerable to the impacts of climate change, such as extreme droughts, heat waves, and wind gusts. Research on microclimates below solitary trees is scarce and a more detailed understanding is needed to better understand and predict the future impacts of climate change on their associated biodiversity and ecosystem services. Here we quantified air temperatures and vapour pressure deficits below the crown of >200 trees along rural-to-urban gradients for three tree species (oak, ash, and lime) across nine European cities. We recorded microclimate measurements every 30 min for 10 months and analysed the effects of the surrounding built-up area and how different tree species influence microclimatic conditions. The microclimate below trees in more urban areas was overall warmer and drier than below rural trees, whereby 10 % more built-up area caused average summer air temperatures to increase by 0.1 °C and average vapour pressure deficits by 0.02 kPa. Oak and lime were able to dampen the temporal fluctuations of air temperature and vapour pressure deficit more than ash and were able to mitigate maximum summer temperatures 0.55 °C more than ash. Our research thus underpins that solitary trees shape their own species-specific microclimate. We advocate for integrated tree planning to preserve and provide space for solitary trees, and by adopting solitary trees as key components of urban and rural green infrastructures, we can improve microclimatic conditions and enhance biodiversity, ultimately creating more sustainable and liveable landscapes.

Context

Habitat loss and land use homogenization cause a decline in biodiversity in agricultural landscapes. Plant community in small landscape features which remain post-land use change (small natural or semi-natural habitats) may overlap with plant community in semi-natural grasslands and buffer species decline in landscapes where little or no grassland remains.

Objectives

We explored if small natural or semi-natural habitats buffer the decline of semi-natural grasslands when it comes to number of plant species with fleshy fruits and a variety of food resources for pollinators, throughout the vegetation season.

Methods

We surveyed plants in grasslands and small habitats in five agricultural landscapes; 13 semi-natural grasslands (area 7016–85547 m²), 50 forest edges (area 145–1850 m²) and 130 midfield islets (area 17–4788 m²). We than explored how the richness of plants and plant traits (fleshy fruits, flower morphology and flowering period) are related to habitat type, landscape and canopy cover in the focal habitats.

Results

Semi-natural grasslands and midfield islets had the highest richness of plant species and flower shapes compared to forest edges. In addition, midfield islets harboured more species with fleshy fruits. When comparing the plant community on midfield islets with the plant community in forest edges, midfield islets and semi-natural grasslands contributed equally with number of blooming plant species during the seasons. Landscapes that were less intensively used (less crop fields) provided food resources for a higher diversity of pollinators compares to less open landscapes, as there was a higher richness of plant species and flower morphologies. Forest edges were not as valuable to pollinators and frugivores as midfield islets.

Conclusions

Small natural or semi-natural habitats can provide food resources to pollinators and frugivores at the landscape scale in fragmented landscapes. More crop field in the landscape had a negative impact on the richness of plants and flower morphologies in the habitats. Forest borders may not be as species rich as midfield islets but are still a part of the green infrastructure in the landscape. Particularly, in intensively managed landscapes, small natural habitats can contribute to landscape plant diversity and have a complementary function to each other, but this does not fully compensate for the loss of semi-natural grasslands.

Questions How do local forest conditions and characteristics at the forest patch - scale and landscape - scale affect plot-scale plant diversity in Europe? Do these patterns vary between forest specialists and generalists? Do community saturation patterns differ between forests varying in their surrounding landscape type?

Location: Deciduous forests sampled along a European gradient from southwest to northeast comprising eight regions in five countries (France, Belgium, Germany, Sweden, Estonia).

Methods: We examined the effects of local conditions assessed by means of Ellenberg indicator values (soil moisture, soil nitrogen, soil pH, light availability), patch-scale characteristics (patch-scale plant diversity, forest patch age, forest patch size) and a landscape-scale variable (representing low and high connectivity of forest patches) on plot-scale plant diversity, separately for forest specialist and generalist species. Additionally, we ran regression models to examine community saturation patterns.

Results: We found patterns of niche partitioning among forest specialists and generalists. Low light availability and medium soil moisture favored forest specialists, while generalists were mostly present at higher light availability and medium and high soil moisture. In general, we found the highest plot-scale diversity at medium soil pH. Patch-scale diversity showed a positive impact on plot-scale diversity and plots in the high-connectivity landscape had a higher diversity than plots in the low-connectivity landscape. Further, we observed a high degree of community saturation in both landscape types.

Conclusion: The positive impact of a high connectivity of forest patches on local plant diversity emphasizes the importance of small semi-natural habitats like tree lines, unused field margins and hedgerows to enhance the potential dispersal of forest plants across agricultural landscapes. Community saturation patterns revealed the increasing relevance of local conditions and processes for plot-scale diversity when patch-scale diversity increases.

Urbanization impacts plant-herbivore interactions, which are crucial for ecosystem functions such as carbon sequestration and nutrient cycling. While some studies have reported reductions in insect herbivory in urban areas (relative to rural or natural forests), this trend is not consistent and the underlying causes for such variation remain unclear. We conducted a continental-scale study on insect herbivory along urbanization gradients for three European tree species: Quercus robur, Tilia cordata, and Fraxinus excelsior, and further investigated their biotic and abiotic correlates to get at mechanisms. To this end, we quantified insect leaf herbivory and foliar secondary metabolites (phenolics, terpenoids, alkaloids) for 176 trees across eight European cities. Additionally, we collected data on microclimate (air temperature) and soil characteristics (pH, carbon, nutrients) to test for abiotic correlates of urbanization effects directly or indirectly (through changes in plant secondary chemistry) linked to herbivory. Our results showed that urbanization was negatively associated with herbivory for Q. robur and F. excelsior, but not for T. cordata. In addition, urbanization was positively associated with secondary metabolite concentrations, but only for Q. robur. Urbanization was positively associated with air temperature for Q. robur and F. excelsior, and negatively with soil nutrients (magnesium) in the case of F. excelsior, but these abiotic variables were not associated with herbivory. Contrary to expectations, we found no evidence for indirect effects of abiotic factors via plant defences on herbivory for either Q. robur or F. excelsior. Additional biotic or abiotic drivers must therefore be accounted for to explain observed urbanization gradients in herbivory and their interspecific variation.

1. In many agricultural landscapes, it is important to restore networks of forests to provide habitat and stepping stones for forest specialist taxa. More knowledge is, however, needed on how to facilitate the immigration of such taxa in restored forest patches. Here, we present the first chronosequence study to quantify the dynamics of immigration credits of forest specialist plants in post-arable forest patches.
2. We studied the distribution of herbaceous forest specialist plant species in 54 post-arable broadleaved forest patches along gradients of age (20–140 years since forest establishment), distance from ancient forest (0–2,600 m) and patch area (0.5–9.6 ha). With linear mixed models, we estimated the effects of these factors on species richness, patch means of four dispersal-related plant traits and with generalized linear models on the occurrence of 20 individual species.
3. Post-arable forest patch age and spatial isolation from ancient forest, but not patch size, were important predictors for species richness of forest specialists, suggesting that also small patches are valuable for habitat connectivity. Compared to species richness in ancient forest stands, the immigration credit was reduced by more than 90% after 80 years in post-arable forest patches contiguous to ancient forest compared to 40% after 80 years and 60% after 140 years in isolated patches (at least 100 m to next forest). Tall-growing species with adaptations to long-distance dispersal were faster colonizers, whereas species with heavy diaspores and clonal growth were slower to colonize.
4. Synthesis and applications. We show that post-arable oak plantations have a high potential for restoration of forest herb vegetation. Dispersal-related plant traits play a key role in explaining interspecific differences among forest specialists. To facilitate forest herb immigration across all functional groups in agricultural landscapes, we suggest to create clusters of relatively small new forest patches nearby older forest with source populations.

Aim: The spatio-temporal connectivity of forest patches in lowland agricultural landscapes and their age matter to explain current biodiversity patterns across regional as well as biogeographical extents, to the point that their effect exceeds the one of macroclimate for plant diversity in the understorey of temperate forests. Whether this remains true for other taxonomic groups is still largely unknown. Yet, this relative influence has important consequences for ecosystem functioning and the delivery of ecosystem services. Focusing on carabid beetle assemblages, we assessed the relative importance of macroclimatic, landscape and patch attributes in driving local species richness (alpha-diversity) and species dissimilarity between patches (beta-diversity).

Location: Deciduous forest patches in seven regions along a 2,100-km-long latitudinal gradient across the European temperate forest biome, from southern France to central Sweden.

Methods: We sampled 221 forest patches in two 5-km x 5-km landscape windows with contrasting management intensities. Carabid beetles were classified into four habitat-preference guilds: forest-specialist, forest-generalist, eurytopic and open-habitat species. We quantified the multi-level environmental influence using mixed-effects models and variation partitioning analysis.

Results: We found that both alpha- and beta-diversity were primarily determined by macroclimate, acting as a large-scale ecological filter on carabid assemblages among regions. Forest-patch conditions, including biotic and abiotic heterogeneity as well as patch age (but not patch size), increased alpha-diversity of forest species. Landscape management intensity weakly influenced alpha-diversity of forest species, but increased the number of non-forest species in forest patches. Beta diversity of non-forest species increased with patch heterogeneity and decreased with landscape management intensity.

Main conclusions: Our results highlight the leading role of broad macroclimatic gradients over local and landscape factors in determining the composition of local carabid communities, thereby shedding light on macroecological patterns of arthropod assemblages. This study emphasizes the urgent need for preserving ancient forest patches embedded in agricultural landscapes, even the small and weakly connected ones.

Global forest loss and fragmentation have strongly increased the frequency of forest patches smaller than a few hectares. Little is known about the biodiversity and ecosystem service supply potential of such small woodlands in comparison to larger forests. As it is widely recognized that high biodiversity levels increase ecosystem functionality and the delivery of multiple ecosystem services, small, isolated woodlands are expected to have a lower potential for ecosystem service delivery than large forests hosting more species. We collected data on the diversity of six taxonomic groups covering invertebrates, plants and fungi, and on the supply potential of five ecosystem services and one disservice within 224 woodlands distributed across temperate Europe. We related their ability to simultaneously provide multiple ecosystem services (multiservice delivery potential) at different performance levels to biodiversity of all studied taxonomic groups (multidiversity), forest patch size and age, as well as habitat availability and connectivity within the landscape, while accounting for macroclimate, soil properties and forest structure. Unexpectedly, despite their lower multidiversity, smaller woodlands had the potential to deliver multiple services at higher performance levels per area than larger woodlands of similar age, probably due to positive edge effects on the supply potential of several ecosystem services. Biodiversity only affected multiservice delivery potential at a low performance level as well as some individual ecosystem services. The importance of other drivers of ecosystem service supply potential by small woodlands in agricultural landscapes also depended on the level of performance and varied with the individual ecosystem service considered. Synthesis and applications. Large, ancient woodlands host high levels of biodiversity and can therefore deliver a number of ecosystem services. In contrast, smaller woodlands in agricultural landscapes, especially ancient woodlands, have a higher potential to deliver multiple ecosystem services on a per area basis. Despite their important contribution to agricultural landscape multifunctionality, small woodlands are not currently considered by public policies. There is thus an urgent need for targeted policy instruments to ensure their adequate management and future conservation in order to either achieve multiservice delivery at high levels or to maximize the delivery of specific ecosystem services.