This study investigates the climate sensitivity and resilience of radial growth in eight coniferous and deciduous tree species in the Vienna Woods, Austria. Using dendrochronological methods, we analyzed tree-ring width data from 63 forest plots to assess growth responses to meteorological variability over the period 1933-2023. Historic climate records were used to develop a water balance model, from which we derived seasonal growth factors. Linear mixed effects models were applied to quantify species-specific relationships between tree-ring width and climatic conditions during the current and preceding two years. Tree-ring width responded not only to climatic conditions of the current growing season but also strongly to those of the previous year. Soil moisture and air temperature emerged as the principal drivers of radial growth, with soil moisture positively and temperature negatively affecting ring width. Climatic conditions during June-July of the current year exerted the strongest impact on ring formation. Using regional climate trends and projected air temperature and precipitation trajectories for Central Europe under RCP4.5 and RCP8.5, we forecast future growing conditions for the region. Both scenarios predict an extended growing season, increased transpiration demand, and heightened drought risk - more pronounced under RCP8.5. However, projected increases in precipitation partly offset the drought risk. By combining historical climate sensitivity of radial increment with future climate projections, we modelled expected tree-ring growth for eight tree species. Most species are predicted to experience notable declines in radial growth, with the strongest reductions in conifers, including European larch (Larix decidua), Norway spruce (Picea abies), Austrian pine (Pinus nigra) and Scots pine (Pinus sylvestris). Deciduous species - Sycamore maple (Acer pseudoplatanus), European beech (Fagus sylvatica), and sessile oak (Quercus petraea) - show moderate declines. In contrast, Turkey oak (Quercus cerris) is projected to increase radial growth under future climate scenarios. These findings suggest that forest management in the Vienna Woods and adjacent regions should prioritize the promotion of warm- and drought-tolerant tree species such as Quercus cerris to enhance forest resilience and sustainability in the face of climate change.

Tree species can exert strong and species-specific controls on water infiltration in forest soils. However, the magnitude and meteorological sensitivity of these effects remain poorly quantified under standardised site conditions. We measured unsaturated hydraulic conductivity ( K ) and soil water repellency index ( R ) in the A horizon beneath seven single-species stands – lime ( Tilia cordata ), sycamore ( Acer pseudoplatanus ), maple ( Acer platanoides ), beech ( Fagus sylvatica ), oak ( Quercus robur ), larch ( Larix decidua ), and Douglas-fir ( Pseudotsuga menziesii ) – in a common-garden experiment on sandy Dystric Gleyic Cambisols. Measurements were conducted in five campaigns representing contrasting 10-day antecedent weather conditions. Broadleaved species such as lime, maple, and sycamore maintained low repellency and high K regardless of preceding weather, indicating low susceptibility to hydrophobicity. In contrast, conifers (Douglas-fir and larch) rapidly developed strong repellency and sharply reduced infiltration following dry spells. Beech and oak showed intermediate responses, with repellency emerging under drought but receding after wet periods. These patterns reveal that species differ not only in baseline hydraulic properties but also in the speed and magnitude of their response to short-term meteorological variability. Our study highlights the importance of species-specific functional traits in regulating soil hydraulic behaviour. Selecting species that sustain infiltration and resist the onset of hydrophobicity could help improve water retention, limit runoff, and enhance forest resilience under projected increases in drought frequency. • Unsaturated hydraulic conductivity and soil repellency were measured in humus-mineral soil horizon beneath seven tree species. • Five campaigns represented distinct 10-day antecedent weather conditions ranging from dry to wet. • Conifers (Douglas-fir, larch) rapidly developed high water repellency and infiltration loss after short dry spells. • Lime, maple, and sycamore remained wettable under all conditions, indicating resistance to drought-induced hydrophobicity. • Beech and oak showed intermediate sensitivity, with repellency peaking only after prolonged dryness.

Urban trees for reconstructing historical trends in atmospheric mercury pollution

A spatially explicit dataset of upper canopy tree species composition of public forests of the Autonomous Province of Trento, Italy.

Effective forest management and climate adaptation require a detailed understanding of tree species-specific disturbance dynamics. In recent years forest disturbances in Central Europe have intensified, driven by rising temperatures and recurring droughts. In Germany, drought and windthrow events since 2018 have triggered unprecedented Forest Canopy Cover Loss (FCCL). Here, we present the first national-scale assessment of FCCL for dominant tree species in Germany from 2018 to 2024, based on multi-temporal remote sensing data. We produced a dominant tree species map for 2016 by majority-voting on annual Sentinel-2 tree species classifications (2016–2024) and filtering with forest structure data. This yields a robust baseline for ten dominant species classes (F1-scores > 0.90 for nine pure-species classes). We quantified FCCL, derived from Sentinel-2 and Landsat time series at monthly intervals and 10 m resolution, by aggregating species-specific canopy loss pixels across different temporal (monthly, annual) and spatial (district, state, and national) scales. FCCL predominantly affected coniferous species: Spruce-dominated forests accounted for 4497 km² (51.3 % of total FCCL), corresponding to 18.6 % of initial spruce area, with peak FCCL in 2020–2021 and a distinct late-summer peak. Pine ranked second with 1893 km² (21.6 % of total FCCL and 7.4 % relative). Deciduous species such as beech and oak were less affected, with total FCCL below 300 km² each and relative declines of 1 %. Spatial hotspots of spruce FCCL were concentrated in central low mountain ranges. Our results provide a tree species-specific overview of forest loss dynamics in Germany, revealing tree species-dependent FCCL since 2018, thus supporting long-term forest management and adaptation to climate change. • First assessment of tree species-specific forest canopy cover loss in Germany • New 2016 dominant tree species map derived from multi-annual Sentinel-2 satellite data • Spruce-dominated forests experience the greatest forest canopy cover loss • Pine losses rank second, while beech and oak forests remain more stable • Species-specific disturbance patterns guide climate-adaptive forest management

Climate change and pest outbreaks are increasingly threatening conifer-dominated forests in Northern Europe, highlighting the need for greater species diversity to improve resilience. This study assessed early establishment success of six tree species: European aspen ( Populus tremula ), hybrid aspen ( P. tremula × P. tremuloides ), silver birch ( Betula pendula ), Norway spruce ( Picea abies ), Scots pine ( Pinus sylvestris ), and hybrid poplar ( P. trichocarpa × P. maximowiczii ), across seven sites in southern Sweden. Sites were categorized as either forest land (continuous forest cover >100 years) or forested arable land (former arable land afforested with Norway spruce for 40–70 years). Over three years, we monitored survival, height, and diameter growth. All experimental sites were fenced to exclude browsing. Wood ash was applied to a subset of hybrid poplars to assess its effect on establishment in acidic soils. Our results showed that hybrid aspen, birch, and European aspen had high survival and growth on forest land. On forested arable land, untreated Norway spruce, Scots pine, and hybrid poplar showed low survival, likely due to competition from dense vegetation. However, ash-treated poplar improved survival to approximately 80% and showed strong growth on forested arable sites. Principal Component Analysis indicated overall higher establishment success on forest land for most species, whereas hybrid poplar performed similarly on forest and forested arable land when wood ash was applied. These findings underscore the importance of matching species to site conditions during early establishment and provide empirical evidence to inform species selection for forest regeneration under similar site conditions in southern Sweden. • Site type strongly influenced establishment success of broadleaved trees. • Hybrid aspen and silver birch had the highest survival and early growth on forest land. • Norway spruce and Scots pine performed poorly on forested arable land. • European aspen performed similarly at both site types, demonstrating flexibility. • Results highlight species-site matching for reforestation in southern Sweden.

Heartwood traits in trees are critical for timber quality but are notoriously difficult to phenotype due to their late expression and the need for destructive sampling. In this proof-of-concept study, we demonstrate that combining genome-wide association studies (GWAS) with Bayesian genomic prediction models provides an effective strategy to overcome these challenges. By using GWAS to preselect trait associated single nucleotide polymorphisms (SNPs) and integrating them into predictive models, we substantially improve the accuracy of genomic predictions for heartwood related traits in oaks. Our approach facilitates reliable selection of superior genotypes within a breeding population, long before heartwood traits can be directly measured, thus enabling early and cost-effective breeding decisions. We also identify the number of rings in sapwood as a genetically controlled, easily measured proxy trait that enhances selection strategies for heartwood content. Together, these findings provide a scalable framework for integrating genomics into operational tree breeding programs and demonstrate how combining GWAS and genomic prediction can accelerate the improvement of complex wood traits in long lived forest tree species. • Heartwood traits are difficult to phenotype as they require destructive sampling. • Genomic prediction enables early selection of superior heartwood genotypes. • Sapwood ring number provides an easy proxy for heartwood content. • Genomics-based breeding framework in oaks transferable to other tree species.

Climate change is causing temperatures to rise across much of the earth, and this warming is amplified in urban areas due to the urban heat island effect. One of the most effective methods of reducing urban heat is expanding the urban forest. However, rising temperatures coupled with increasing drought intensity create challenges for the establishment of newly planted trees in cities. Obstacles to urban tree establishment are exacerbated in legacy cities, which have limited financial resources to plant and manage trees. In summer 2024, we conducted a large-scale field study in Dayton, Ohio, USA to address the challenges of expanding the urban forest in a legacy city. To determine low-cost solutions for urban forest expansion, we supplied 640 newly-planted native saplings with varying levels of irrigation investments across 20 parks in Dayton. We then monitored sapling survival, growth, and health in response to our irrigation investments and surrounding impervious surfaces within a 500-m radius of each planting site as a proxy for heat. We found that the effects of both irrigation treatment and surrounding heat varied among tree species. Overall, approximately 50% of planted saplings survived to the end of the growing season, and many saplings went missing due to anthropogenic disturbance. Therefore, we recommend a tailored approach to urban forest expansion which takes species, resources available for irrigation, and surrounding imperviousness into consideration to inform sustainable urban reforestation plans.

This study presents a detailed floristic inventory of the spontaneous flora in La Asomadilla urban park in Córdoba, southern Spain. In addition to being the largest urban park in the city, La Asomadilla is characterized by irregular terrain, a transitional location between the Guadalquivir river plain and Sierra Morena mountains, and the predominance of native vegetation with a naturalized appearance rather than a formal garden design. These characteristics make the park an important reservoir of biodiversity and a barrier against the spread of invasive species. A total of 250 species belonging to 60 families were recorded, predominantly therophytes adapted to Mediterranean climatic conditions. Two species (Cyperus eragrostis and Valerianella microcarpa) were recorded for the first time in the municipality, along with five orchid species of high ecological value. Several allergenic taxa were identified, primarily belonging to the Poaceae, Asteraceae, and Oleaceae families, highlighting the importance of considering the impact on public health in the management of urban biodiversity. Unlike most studies on urban green spaces, which focus mainly on ornamental or tree species, this research highlights the relevance of the accompanying wild flora. These species not only contribute to climate change mitigation by reducing temperatures and capturing CO2 but also provide health benefits for the population. Therefore, this study provides novel and valuable data at the local level to inform ecological and public health management strategies in Mediterranean urban areas.

Changes in decomposition rates and nutrients of leaf litter and fine roots in urban tree species under ozone pollution

Urbanization in recent decades has led to changes in the structure of communities and ecosystem functions, including pollination and seed dispersal. Many plants rely on biotic vectors for these stages of their reproduction, while many animals depend on the plant resources acquired through these interactions. However, how these interactions overlap in urban environments is not well known. Here, we built multi-layered bird-plant networks characterizing resource use (nectarivory/frugivory) and ecosystem functions (pollination/seed dispersal) from an urban community in Brazil, asking whether biodiversity conservation can be optimized by considering multiple interactions simultaneously. The multilayer networks involving 86 bird and 108 plant species showed low modularity, indicating weak partitioning of interactions. Nevertheless, bird families showed specific associations across modules, indicating some preferences in resource use. Nevertheless, native and non-native plants were broadly distributed across modules, illustrating how the latter are embedded in urban ecological networks. Few species stood out as important contributors to multilayer network structure, including both native and non-native tree species. We find that no plant simultaneously provided both flower and fruit resources in equal importance, even with considerable overlap in the interaction layers. Our study illustrates the use of a recently developed network approach that can be applied to assess multiple interaction types simultaneously. This approach may be useful in finding species that contribute to multiple ecosystem functions simultaneously, or as in our case, show that although some overlap exists, different plant species are needed to fulfil distinct needs for bird species to promote biodiversity-friendly cities.

Diffuse-porous and ring-porous xylem types did not influence branch hydraulic responses along a rural-urban gradient

Planted forests in dry Mediterranean regions are increasingly threatened by extreme climatic events, making adaptive management strategies such as thinning and underplanting essential. To apply these restoration practices at large scales, it is necessary to understand how different tree species respond to varying thinning intensities. This study evaluated the performance of seedlings from four late-successional, resprouting Mediterranean broadleaf species — Acer monspessulanum L., Quercus pyrenaica Willd Sorbus torminalis (L.) Crantz, and the evergreen Quercus ilex L. subsp. ballota (Desf.) Samp— underplanted along a canopy openness gradient created by thinning treatments in a 50-year-old Pinus pinaster plantation. Four thinning treatments were compared: no thinning (control), moderate thinning from below (20% basal area reduction), heavy thinning from below (35%), and heavy thinning from above (35%), leaving 28.7, 24.9 and 23.2 m 2 ·ha −1 residual basal area, respectively. Thinning significantly increased light availability, throughfall, and soil moisture, with most improvements occurring under moderate thinning. Soil water availability increased at deeper soil layers in all thinned stands, while shallow soil moisture improved mainly under moderate thinning. After five years, seedling survival was high (>80%) across all species and generally increased with greater canopy openness. Quercus pyrenaica and Q. ilex showed the strongest positive response in survival to increased canopy opening, whereas A. monspessulanum and S. torminalis were less affected, likely due to differences in functional traits. Seedling growth was also enhanced by thinning, reaching maximum rates under moderate thinning, with S. torminalis exhibiting the highest growth and A. monspessulanum the lowest. Improved seedling performance under thinning was associated with reduced summer water stress and higher photochemical efficiency during dry periods. Overall, the study demonstrates that moderate thinning creates optimal environmental conditions for the facilitation of underplanted seedlings and provides guidelines for promoting structural and species diversification in Mediterranean pine plantations. • Thinning increases resources and the performance of underplanted seedling. • Seedling water and photosynthetic stress is alleviated under moderate thinning. • Response of underplanted seedlings to canopy openness is species-specific. • Thinning and species mixing speeds the conversion of monospecific pine plantations.

Lianas are particularly abundant in seasonally dry tropical forests, where most species flower during the dry season. While hydraulic differences of vegetative organs between lianas and trees are well-documented, floral hydraulic strategies and their potential role in liana expansion remain unclear. To characterize divergence in floral water-use strategies between lianas and trees, we examined 24 floral traits related to water transport, storage, drought tolerance, and pollinator attraction in 16 liana and 16 tree species of Bauhinia s.l. from a tropical seasonal rainforest in Yunnan, China. Liana flowers exhibited greater petal vein density, stomatal density and size, flower mass per area, and drought tolerance than tree flowers, which showed higher saturated water content and hydraulic capacitance. Liana flowers exhibited a trade-off between hydraulic efficiency and safety, but trees did not. Life forms also differed in trait coordination linking hydraulic structure, function, and reproduction. Our findings reveal divergent floral hydraulic syndromes: lianas adopt structurally reinforced, drought-tolerant designs for canopy flowering under high vapor pressure deficit, while trees rely on internal water reserves to buffer water loss. This study provides the first organ-level evidence that divergent floral hydraulic strategies underpin reproductive success and may help explain liana dominance in seasonally dry tropical forests under climate change.

Data-driven interpretability of urban tree species classification from deep learning models and Satellite Image Time Series

Hyperspectral remote sensing is a powerful, high-throughput phenotyping tool that quantifies physiologically and structurally relevant wavelengths across diverse genotypes and over varying temporal scales. In this study, we combined tower-based continuous hyperspectral sensing with genome-wide association studies to analyze 1,423 wavebands (400-900 nm) and derivative vegetation indices across 505 genotypes and the genetic architecture of hyperspectral phenotypes over time in Populus trichocarpa Torr. & Gray grown under field conditions. Wavelengths related to chlorophyll and carotenoid absorption spectra exhibited the strongest genetic variation resulting in 98 significant SNP associations. Notably, we found substantial overlap in genetic association between the blue and red spectral regions, indicative of carotenoids and chlorophyll, respectively, and identified more than 10 candidate genes associated with chloroplast function, underpinning photosynthetic activity. Furthermore, fluctuations in associations for vegetative indices, such as the chlorophyll:carotenoid index (CCI), across the growing season reveal a temporally dynamic genetic architecture of physiological traits associated with fall senescence of this temperate tree species. Finally, we also observed correlations (⍴=0.3, p<1x10 -8 ) between individual wavebands or vegetative indices and growth rate, assessed as the relative change of tree height over the growing season. The growth rate prediction was substantially improved by a regularization multivariate model (⍴>0.5, p<1x10 -16 ), reinforcing the value of hyperspectral measurements for predicting traits linked to tree productivity. These findings highlight the potential of high-throughput, rapid, hyperspectral genome wide association studies GWAS to uncover physiologically meaningful genetic variation and offer promising insights for future acceleration for plant breeding.

Drought rather than nitrogen addition drives the coordination of hydraulic conductivity and photosynthesis in three coniferous tree species

Prior research has demonstrated that the natural regeneration of Korean pine ( Pinus koraiensis ) in old-growth forests is quantitatively constrained by the composition of parent trees. To further explore the spatial relationships between regenerated and maternal Korean pine, we examined the spatial patterns of its regeneration across four ontogenetic stages (younger seedlings, older seedlings, smaller saplings, and taller saplings) in five old-growth mixed forest stands representing a gradient of Korean pine basal area proportion (33%-77%). Using spatial point pattern analysis with crown-projected coordinates, we quantified intra- and interspecific spatial associations. Results revealed that Korean pine natural regeneration is forest-type-specific, with the ribbed birch ( Betula costata )-Korean pine forest being the most conducive to regeneration. Distribution patterns indicated a density-dependent ontogenetic shift: regenerated individuals exhibited strong aggregation at the early stage, which shifted to a random-dominated distribution in later stages, a trend amplified in stands with higher proportions of Korean pine. Associations between younger seedlings and parent trees transitioned from fine-scale facilitation to broad-scale repulsion ( p < 0.05), but only where the Korean pine proportion was approximately 50%. Notably, most heterospecific associations were neutral, with facilitation being highly species- and context-specific. We conclude that high conspecific occupancy intensifies intraspecific competition, whereas neutral associations with broadleaved species suggest that niche partitioning governs coexistence. Conservation strategies should therefore focus on regulating parent tree density and maintaining stand diversity to ensure sustainable regeneration. Methodologically, we recommend that future point pattern analyses of large canopy trees, particularly those with severe crown asymmetry, using crown coordinates.

Unexpectedly high aldehyde emissions from stems of six major European tree species

Functional traits are better than climate niche approach at predicting the vital growth and mortality rates of urban tree species