Increasing air temperatures and summer drought increasingly constrain tree growth across the Mediterranean region, but these responses occur within landscapes modified by urbanization, industrial infrastructure, and artificial land cover. How anthropogenic landscape context alters climate-growth relationships remains poorly understood, especially in planted stands and across spatial scales. Here, we investigated tree-ring growth of planted Pinus halepensis Mill. stands across 41 sites spanning contrasting levels of anthropogenic pressure in southern Italy. Using hierarchical mixed-effects models, we tested whether anthropogenic proxies act as additive drivers of radial growth or instead modify sensitivity to summer temperature and hydroclimatic variability.Summer mean temperature was the dominant climatic constraint on growth, whereas SPEI-12 showed a weaker but consistent additional effect. Anthropogenic variables had limited and inconsistent additive effects on ring width, but strongly modified climate sensitivity through interaction effects. Local artificial land cover, especially within 1 km, consistently amplified sensitivity to summer heat and was the strongest anthropogenic moderator of growth responses. By contrast, hydroclimatic sensitivity was spatially heterogeneous, with attenuated SPEI responses near the industrial core and stronger responses farther away. A final random-slope model confirmed that this amplification persisted after accounting for heterogeneity among sites and individual trees.Our results show that landscapes heavily impacted by human activities do not simply shift growth levels, but reshape climate-growth relationships in planted Mediterranean pine stands. Fine-scale human modification should therefore be considered when assessing planted-stand vulnerability to future warming.

Forest ecosystems are increasingly vulnerable to climate change, particularly through rising temperatures and more frequent extreme droughts. Understanding how environmental heterogeneity shapes tree growth and drought responses is essential for predicting forest dynamics under these changing conditions.We investigated how fine-scale environmental heterogeneity, defined by micro-environmental (topo-edaphic) differences, modulates radial growth, climate sensitivity and drought resilience in Araucaria araucana, a keystone and endangered conifer native to Patagonian forests. We analyzed tree-ring series from 156 individuals across four forest stands in Argentina, spanning a broad regional mesic–xeric gradient and contrasting within-site environmental conditions. Growth sensitivity to drought was assessed using dendrochronological techniques, correlation analyses with atmospheric and soil moisture drought indices, and resistance and resilience metrics, the latter calculated using flexible, tree-specific recovery windows.Micro-environmental variability exerted a strong influence on growth patterns: within sites, trees in mesic units exhibited higher growth rates, while those in xeric units showed reduced radial growth. Growth–environment (climate and soil moisture) relationships varied across the regional gradient: in the wetter western range, growth was influenced by both atmospheric and edaphic conditions, while towards the drier eastern limit, atmospheric drivers predominated. Regardless of large-scale geographical distribution, trees in xeric micro-environments consistently showed greater sensitivity to climatic and soil moisture variability than their mesic counterparts.Drought responses reflected interacting effects operating across spatial scales. Micro‑environment determined baseline resistance and resilience, whereas the influence of climatic conditions before, during, and after drought events was contingent upon the macro‑regional context, as evidenced by the distinct response patterns of micro-environmental units located in the western (mesic) versus the eastern (xeric) regions. The flexible resilience index developed in this research proved more sensitive to inter-individual variation in post-drought recovery than traditional fixed-window metrics, suggesting its potential as a complementary metric in resilience studies.

Microbial biostimulants are increasingly proposed as sustainable tools to enhance crop performance and resilience under climate change. However, their ecophysiological effects and underlying mechanisms remain insufficiently understood, particularly in woody perennial species. This study investigated the effects of MICOSAT F® microbial biostimulant on growth and ecophysiological traits of two-year-old Olea europaea L. cv. Leccino plants under controlled greenhouse conditions. For the first time, we integrated agronomic measurements with dendrochronological analyses and intra-annual assessments of carbon and nitrogen concentration (C%, N%) and their stable isotope composition (δ¹³C, δ¹5N) in tree rings. Biostimulant-treated trees exhibited significantly larger stem diameter, height, lateral branching, and total biomass compared with controls. Treated trees showed lower stem wood C%, suggesting increased C allocation to non-structural carbohydrates and belowground symbionts. Furthermore, treated trees displayed significantly depleted δ¹³C values with reduced interannual variation, indicating enhanced stomatal conductance and more stable photosynthetic discrimination. Depleted δ¹5N signatures reflected a shift toward microbially-mediated N acquisition pathways rather than increased absolute N availability. These findings demonstrate that MICOSAT F® biostimulant fundamentally alters plant C and N metabolism, promoting growth while enhancing physiological stability - key traits for potential climate resilience in sustainable olive cultivation systems.

Climate change threatens forest ecosystems by increasing frequency and intensity of extreme climatic events. In southern South America, extreme late-spring frost (LSF) episodes can cause severe leaf damage, leading to reduced tree growth and productivity and shortening the effective growing season. Nothofagus pumilio, a hardwood species Tierra del Fuego forests, is an ecologically important resource providing several ecosystemic services. We evaluated the growth resilience of 50 trees across three sites near treeline in Tierra del Fuego to examine LSF impact by quantifying individual resistance (immediate impact) and resilience (recovery capacity) in response to two distinct extreme frost episodes: a single-year (1979) and consecutive three-year event (2007-2009).The three-year LSF caused significantly greater reductions both in resistance and resilience compared to the single-year event. Statistical modelling revealed that tree resistance was negatively affected by higher frost-day frequency during each event relative to the preceding LSF period, while resilience was reduced by unfavorable (lower temperatures) post-event climatic conditions. Notably, fast pre-event growth rates increased tree vulnerability to the single-year frost event, while they had a weaker effect during the prolonged three-year episode, suggesting a stress threshold beyond which intrinsic growth strategy becomes less relevant. Our findings showed that N. pumilio has a limited capacity to tolerate and recover from multi-year frost stress, highlighting its vulnerability to consecutive extreme climate events. We conclude that conservation strategies for high altitude N. pumilio forests must account for the species’ differential sensitivity to frost event frequency under future climate scenarios.

Intra-annual density fluctuations (IADFs) are wood cells formed in response to abnormal climatic events during the growing season. They are crucial for evaluating the relationship between extreme climatic events and radial growth, as well as for understanding wood quality. However, most existing research has focused on seasonally dry Mediterranean and semi-arid conifer forests, with limited studies conducted in other regions—particularly subtropical forests, where frequent and severe droughts constrain forest productivity and growth. Here, we investigated the occurrence patterns and triggering factors of IADFs in Pinus massoniana plantations along a climate gradient in southern China. We found that latewood IADFs (IADF-L) are the predominant type formed by P. massoniana, whereas earlywood IADFs (IADF-E) are relatively rare. The frequency of IADFs showed a clear spatial pattern, gradually increasing as climate conditions became warmer and wetter. IADF-L frequency was negatively correlated with elevation but positively correlated with tree-ring width. High precipitation in late summer and early autumn, as well as hot and dry conditions during summer, triggered the formation of IADF-Ls, while spring (May) droughts induced IADF-E. The inferred climatic drivers of IADFs were further confirmed by climate-growth relationships based on seasonal wood data and the VS-Lite tree-ring growth model. Our findings provide a valuable foundation for developing management strategies for drought-prone subtropical pine forests. For example, artificial rainfall or supplemental irrigation during summer-autumn dry spells could stimulate the formation of IADF-Ls, thereby enhancing forest growth and carbon sequestration capacity.

Broadleaf afforestation increasingly requires selecting planting material that combines valuable wood properties with resilience to climate stress. High heartwood content is a desirable trait in pedunculate oak (Quercus robur), but it is unclear whether selecting for it could compromise resistance and resilience to drought performance. We addressed this question in a progeny trial started in 2002 in southern Denmark where trees were ranked by heartwood production and the 2018 drought was used as a natural stress event. Trees with contrasting heartwood content were assessed using multiple indicators of drought response, including annual ring width, vessel anatomy, wood density, and dual stable isotopes (δ¹³C and δ¹⁸O) measured in earlywood and latewood over five years. The 2018 summer drought (SPEI3 approximately -1.5) was clearly reflected in isotopic signals, indicating that trees perceived the water deficit. However, radial growth did not decline, and ring widths remained above average in 2018. Climate-growth relationships suggested that growth at this site is more strongly limited by cool springs or wet summers than by moderately dry early-summer conditions. Across all metrics, trees with lower and higher heartwood content showed broadly similar physiological and wood-structural responses. Within the environmental conditions and drought intensity observed here, these findings do not provide evidence for a strong trade-off between heartwood content and drought response. They therefore support, with appropriate caution, the continued consideration of heartwood content as a selection trait in breeding and afforestation programs in comparable environments.

Understanding the spatiotemporal variability of climate–growth relationships is critical for predicting forest responses to environmental change and guiding sustainable forest management. However, research on this subject in subtropical conifer species remains limited. We quantified spatiotemporal growth patterns and climatic drivers of Pinus massoniana Lamb across 32 sites spanning the climate gradient of subtropical China. Across the study area, the overall growth of P. massoniana exhibited an increasing trend, with growth declines observed only at a few sites in the central region. Temperature was positively correlated with growth in colder northern regions but negatively correlated with growth in warmer southern regions, whereas growth in the central region showed a significant positive correlation with relative humidity. This indicates that tree growth is primarily constrained by region-specific climatic factors, including high temperatures in the south, drought in the central region, and low temperatures in the north. Furthermore, drought stress has increasingly limited the growth of central and southern P. massoniana populations over time. Simulations based on the VS-Lite model further revealed divergent growth phenological patterns: Northern trees display a unimodal growth pattern, while central and southern populations exhibit a bimodal pattern. Under three projected future climate change scenarios, tree growth in the central and southern regions is projected to exhibit more pronounced declines. This study highlights the importance of accounting for the spatiotemporal variability of climate–growth relationships when developing forest management plans, including those for future plantations. Effective management should prioritize region-specific strategies to mitigate the impacts of climate change, ensuring the resilience of P. massoniana subtropical forests.

Stradivari's violins represent the pinnacle of classical instrument making, yet the origins of the wood used to construct their soundboards have long remained unclear. By analysing 314 tree-ring series from 284 authenticated instruments, we show that the majority of soundboards were crafted from Norway spruce (Picea abies) that grew at very high elevations during the severe climatic conditions of the Maunder Minimum. Our data reveal that Stradivari frequently used wood from the same tree for multiple instruments and that its sources can be traced to the Eastern Alps. Comparison with 197 reference chronologies indicates that Stradivari's early work drew on diverse and less easily localised sources. During his "golden age" of production from the early eighteenth century onwards, he consistently selected spruce from high-altitude forests in Trentino, Italy, and most likely from the Val di Fiemme in particular. These findings provide the first large-scale dendrochronological evidence for the geographic and environmental origins of Stradivari's wood and offer new insights into both historical instrument making and the interplay between climate, materials, and musical heritage.

Small wetlands (SWs, <8 ha) are numerically dominant globally, yet their disproportionate microclimatic regulation remains insufficiently understood across contrasting landscape contexts and hydroclimatic gradients. Here, we quantified growing-season cooling intensity (WCI, land surface temperature reductions) and efficiency (WCE, cooling area per unit wetland area) of 21,879 SWs across China, while elucidating the dominant climatic and spatial drivers governing their variability, through the integration of high-resolution remote sensing, detailed morphological metrics, and interpretable machine-learning. Results revealed widespread localized cooling intensity and remarkably high efficiency (mean WCI =  − 0.52 ± 1.57 °C, mean WCE = 27.69 ± 25.14), with 64.8% of SWs functioning as net thermal sinks. SW cooling was most pronounced in bareland and grassland landscapes due to strong hydrothermal contrasts, moderate in urban contexts limited by impervious surfaces, and weakest in agricultural settings with managed hydrology. Climatic factors, specifically climatic aridity (AI), atmospheric aridity (VPD), and temperature, emerged as the primary controls on SW microclimatic regulation, while morphological features (size, boundary complexity, and shape irregularity) exerted significant secondary and threshold-dependent effects. Optimal cooling occurred under high climatic aridity (AI ≤ 0.5) and moderate atmospheric aridity (VPD 1.0–1.7 kPa) within small patches (0.7–2.2 ha). This national-scale assessment advances high-resolution remote sensing for quantifying biogeophysical feedbacks and provides quantitative evidence for utilizing SWs as scalable nature-based solutions to mitigate local heat stress and enhance ecosystem resilience under intensifying hydroclimatic extremes.

Tree growth sensitivity to moisture availability is pivotal for assessing the forest adaptability to changing water availability and projecting future carbon sequestration and forest health. Climate warming could reshape the temporal shifts in moisture sensitivity, but both the direction and strength, and the underlying drivers remain unclear. In this study, we compiled a pan-continental tree-ring width dataset consisting of 2505 chronologies across the Northern Hemisphere in the period of 1960-2020. Using this dataset, we quantified the spatial patterns, temporal trends and climatic drivers of temporal variations in tree growth sensitivity to moisture. Specifically, we investigated the factors driving the warming effects on temporal variations in moisture sensitivity. We revealed that tree growth in over 78% of the studied forest stands was limited by moisture availability. The moisture sensitivity of tree growth increased in similar to 50% of forest stands, and it decreased in the remaining similar to 50%. Climate warming has contrasting impacts on moisture sensitivity. It enhances the moisture sensitivity in water-limited forests, and for tree species with drought-adapted hydraulic traits, but reduces that in energy-limited forests and for drought-vulnerable tree species. Our findings highlight the pivotal roles of background climate conditions and hydraulic traits of tree species in determining the forest vulnerability in a warmer climate regime. These insights are essential for guiding effective forest management practices and enhancing the accuracy of forest ecosystem modeling.

It is well established that changes in climatic conditions across Alpine environments have influenced tree-growth at altitudes close to the tree line. Less well known is the impact that increasing proportions of glacial melt water, which may accompany increasing temperatures and otherwise drier conditions during warmer summers, have on the tree growth along the glacial outwash rivers within the basin. In many Alpine basins in Switzerland, hydropower development further alters natural hydrological regimes by modifying runoff timing and flow composition. This study investigates the combined effects of climate variability and hydropower regulation on tree growth and isotopic compositions in the Turtmann River Basin in south-west Switzerland, where an upstream hydropower dam (2200 m a.m.s.l.) stores almost all glacial meltwater, and therefore, the riverine flow below the dam becomes increasingly dependent on snowmelt and rainfall from the unglaciated and unexploited basins. We analysed 75 years (1946-2020) of delta O-18 and the delta H-2 values in earlywood (EW) and latewood (LW) Larix decidua growing proximal and distal to the river at two sites within the Turtmann basin. The results show that tree ring growth was primarily temperature-limited at both sites, with a tendency for precipitation becoming a growth-limiting factor particularly at the downstream Site 2 in recent decades. The LW showed stronger climatic sensitivity than EW, reflecting increasingly dry summer conditions. Both delta O-18 and delta H-2 values of proximal trees are lower compared with those of the distal trees, reflecting snowmelt and summer precipitation but are not influenced by the glacial meltwaters draining from the upper catchment and/or released by the dam. These results demonstrate that tree-ring stable isotopic compositions can effectively trace changes in Alpine hydrologic regimes and provide valuable insights into how climate change and hydropower operations combine to influence water availability and tree growth dynamics in glaciated basins.

Over the past two decades, the occurrence of extreme climatic events in the Mediterranean region has increased, and this climatic pressure has contributed to the spread of vegetation dieback over several forest communities. Dieback has also affected Quercus ilex L., and since this decline has worsened over the last 15 years in many Mediterranean areas, it is crucial to develop effective tools for studying this phenomenon, combining different scales of measurement. Our study was conducted over four years (2019-2023) in declining (D) and non-declining (ND) Q. ilex stands in southern Tuscany (IT), assessing physiological and biochemical traits such as gas exchange, water relations, carbohydrate analysis in the wood, and xylem sap isotopic signal (δ18O). Dendrochronological and tree-ring δ13C analyses were combined to investigate the effects of previous droughts on tree growth and water-use efficiency.The results of physiological analyses showed that seasonality had a strong effect on these traits, with the main stress occurring during the summer of 2020, as evidenced by the lowest gas exchange values. According to the results of δ18O analyses, holm oaks mainly took up water from deep soil sources (bottom soil or groundwater) owing to their deep-root systems, resulting in only slightly different ring-width patterns and a low responsiveness to seasonal climatic variations in both stands. By contrast, the δ13C results combined with SSR genotyping revealed a more conservative water use of the population in the ND stand, underlying the potential of combining these powerful tools for the selection of seed-bearing genotypes putatively tolerant to water deficit.

The Numidian cypress (Cupressus sempervirens var. numidica, C. numidica hereafter) is a rare, almost unknown, endemic taxon of Tunisia whose conservation has long been hampered by human activities, taxonomic uncertainty and limited ecological knowledge, with only 64.33 ha of its populations remaining. Although recent genetic studies have confirmed its native status and long-term isolation, detailed information on its distribution, population structure and threats remain lacking. This study provides the first comprehensive assessment of C. numidica across its remaining range. Field surveys revealed that the species persists in only three small, fragmented forests, Bou Abdallah, Sidi Amer, and Dir Satour, covering a total of 64.33 ha. Soil analysis revealed some differences among sites, with Bou Abdallah showing higher clay content and Dir Satou exhibiting the highest levels of nitrogen, organic carbon, Olsen P, and available Mn and Mo. Climatic analyses indicate a semi-arid Mediterranean environment with pronounced summer droughts and a clear warming trend. Trees showed widespread damages, due to intensive grazing, tree cutting, crown dieback (drought), and pest and pathogen attacks. Natural regeneration was limited, and the condition of affected trees ranged from moderate to severe, with Bou Abdallah showing the highest levels of degradation. Notably, the severe fungal pathogen Seiridium cardinale, causal agent of cypress canker, was detected on C. numidica for the first time, highlighting an urgent conservation concern. Our results point to a staged conservation approach over time. In the immediate term (within 1 year), urgent monitoring and management of S. cardinale is needed. In the short term, efforts should focus on protecting carefully selected areas, about 5-10 regeneration microsites per forest, from grazing to support natural regeneration, reduce ongoing soil degradation, and establish clonal and seed-production plantations along with long-term seed storage. In the long term, the survival of C. numidica will only be possible with the active involvement of local communities, through awareness campaigns, adapting traditional practices such as gdel, and developing small-scale ecotourism that provides sustainable livelihoods while reinforcing support for conservation.

Since 2010, when Allen et al.'s highly-cited seminal paper was published in Forest Ecology and Management, a flood of studies have been published on the impact of drought on forest health and condition as well as tree physiology, greatly advancing our understanding of tree physiology and mortality processes. However, these findings have been interpreted by many as signs of a global forest decline due to the increasing frequency and severity of droughts linked to climate change. Upon closer examination of the literature, it appears that forest decline is limited to certain areas in certain regions and is not always induced by drought and associated or related disease and pest attacks, but also by other disturbances, such as windstorms or forest fires. All these disturbances are often facilitated by past changes in land use, such as afforestation in not suited sites or deforestation due to conversion of land to agricultural crops. Social pressure on land and forest appears to play a key role in forest decline, in addition to the role played by drought, as in the case of the forest decline observed in Central Europe in the 1980s, probably triggered by the drought of 1976, although it is generally believed to have been caused by atmospheric pollution.

As global warming drives plant upward migration, the alpine tundra of Changbai Mountain is experiencing encroachment by Deyeuxia angustifolia (Komarov) Y. L. Chang, a low-elevation herb. However, its impact on native shrubs such as Rhododendron aureum Georgi remains unclear. Here, we analyzed the radial growth trends and climate sensitivity of R. aureum across elevations and encroachment gradients using linear and mixed-effects model methods, and explored the mediating roles of soil properties and plant traits. Our study revealed that R. aureum exhibited stronger positive long-term growth trend at higher elevations compared to lower elevations. Mild and moderate encroachment of D. angustifolia enhanced the positive growth trend of R. aureum, especially at the low elevations. Moreover, R. aureum showed weak climate sensitivity at mid-elevation but stronger responses to winter temperatures at low elevation and to spring-summer temperatures and precipitation at high elevation. D. angustifolia encroachment further intensified this sensitivity, characterized by stronger negative responses to spring, autumn and winter temperatures but positive responses to summer temperatures and autumn precipitation. Overall, elevation primarily influenced R. aureum growth and its sensitivity to precipitation through soil conditions and plant size traits, while soil conditions and leaf economic traits influence temperature sensitivity. These findings advance understanding of alpine vegetation dynamics and contribute to ecosystem conservation under climate change. Increasing elevation and herbaceous encroachment synergistically enhanced the growth trend and climate sensitivity of the alpine tundra shrub Rhododendron aureum on Changbai Mountain, with a stronger encroachment effect observed at lower elevations. Rising elevation and herbaceous encroachment jointly enhanced the growth trend and climate sensitivity of the alpine tundra shrub Rhododendron aureum on Changbai Mountain, with the encroachment effect being more pronounced at lower elevations. The findings deepen our understanding of alpine vegetation shifts and invasion mechanisms under climate change, offering scientific guidance for ecosystem conservation and management in alpine tundra regions. (sic)(sic):(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(Deyeuxia angustifolia (Komarov) Y. L. Chang)(sic)(sic)(sic)(sic)(sic).(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(Rhododendron aureum Georgi)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic):1)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic);(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).2)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic),(sic),(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).3)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic), (sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic)(sic).

it is unclear whether pronounced droughts reaching the most remote regions of the Congo Basin are within a historical norm or have occurred only in the last decades. There is a growing evidence that a number of species with anatomically distinct rings can be used for dendroclimatological studies in the Congo Basin, such as Afrormosia (Pericopsis elata) (PEEL). Annual growth increments, i.e. Tree-Ring Width (TRW), are often co-determined by many environmental factors and yield low potential for reconstructions. Earlier work has shown that δ18O measured in PEEL tree rings holds a precipitation amount effect. Here we focus on new P. elata isotope series to estimate the isotope-precipitation relationship at the annual-scale and discuss its potential for reconstructing precipitation variability back to 1850 AD. δ18O values yielded better sensitivity as well as coherence between trees compared to TRW. Lower δ18O values (28-29‰) after 1960 reflect the anomalously wetter conditions between 1950 and 1970 recorded in the Congo Basin and neighbouring areas. Higher δ18O values after 1970 are in agreement with the reduction in precipitation reflected in gauges and satellite data. Further comparisons with instrumental data and other proxies can refine a precipitation reconstruction currently extending to 1850 AD.

Abies alba Mill. is a prominent European tree species predominantly inhabiting cool and humid montane environments. However, paleoecological evidence reveals that during the Eemian and mid-Holocene, A. alba thrived in much warmer and drier climates. This capacity is nowadays reflected in cryptic meso- and sub-Mediterranean lowland populations. To link A. alba populations across diverse climates spanning from the Mediterranean lowlands to the Alpine timberline, we genotyped 421 specimens from Italy and Switzerland at 190 single-nucleotide polymorphisms (SNPs). Population genetic structure analyses indicate that isolated meso- and sub-Mediterranean lowland populations in Tuscany and Ticino align genetically with higher elevation populations in each region, suggesting that their capacity to thrive in warmer, drier conditions cannot be attributed to plantations with planting stock originating from different climates or to the occurrence of a single warm-adapted lineage showing a disjunct distribution, unless migration between Tuscany and Ticino stands occurred. Genotype-environment associations reveal that temperature seasonality, precipitation during critical seasons, and relative humidity are important for explaining the species' genetic variation. With genotype-environment and genotype-phenotype associations, we identified candidate adaptive genes potentially linked to climatic conditions and drought response. While certain adaptive alleles may have spread from Tuscany and Southern Italy or could be explained by a shared ancestry of Ticino and Tuscan populations, local adaptation may have occurred at specific loci. These findings underscore the importance of considering the hitherto overlooked lowland Mediterranean populations of A. alba to better understand the species' climatic niche and its potential for forest conservation and management under global warming.

The olive tree (Olea europaea L.), a key crop in Mediterranean climates, is increasingly affected by climate variability. Over the last several decades, the Umbria region of central Italy, with its long-standing olive-growing tradition, has experienced a rise in extreme summer droughts, severely impacting water availability. This makes it an ideal case study for investigating olive tree responses to climatic stress. In this study, we examined the adaptive strategies of three economically important cultivars – Arbequina, Arbosana, and Koroneiki – grown as mature trees (7 years old) between 2020 and 2023. We combined dendrochronological techniques, wood anatomical analyses, and intra-seasonal δ¹³C profiling to assess growth dynamics, structural adjustments, and eco-physiological responses across four growing seasons. Our results revealed distinct cultivar-specific strategies in response to climate variation. In Arbequina and Arbosana, δ¹³C values showed significant correlations with current-year spring and summer climate conditions, as well as with conditions during the preceding winter, reflecting a more isohydric behavior. In contrast, Koroneiki exhibited a more anisohydric strategy: its δ¹³C values were primarily influenced by precipitation from the previous winter, indicating a reliance on stored carbon reserves to support early-season growth. Wood anatomical traits further supported these differences. Koroneiki exhibited higher vessel density and a greater proportion of lumen area, traits that enhance water transport efficiency. It also achieved the highest stem basal area and fruit production among the three cultivars, reaching 10.2 kg/tree in 2023. These characteristics highlight Koroneiki’s potential as a drought-resilient cultivar suited for future orchard designs in Mediterranean regions increasingly affected by heat and water stress.

The xylem anatomy of diffuse-porous tree species in temperate forests affects their water transport efficiency and drought resistance, thereby affecting their growth and survival. However, it remains unclear how xylem anatomical traits of different diffuse-porous species respond and adapt to warming and drying climate. Here, we assessed the main climate factors driving xylem anatomy of four dominant diffuse-porous tree species (Acer mono, Betula platyphylla, Populus davidiana, and Tilia amurensis) in the temperate forests of northeastern China. We identified distinct vessel patterns among the four species: A. mono and B. platyphylla exhibited larger, sparse vessels, whereas P. davidiana and T. amurensis displayed more small vessels. All xylem anatomical traits were categorized into three distinct clusters largely representing vessel number, vessel size and vessel density. Drought, caused by rising temperatures and declining precipitation, affected xylem formation, while the growth of the four species did not benefit from warming despite the rather low annual mean temperature of 3.0 degrees C. A. mono is mostly influenced by prior-year climate, and B. platyphylla has low climate sensitivity, while P. davidiana and T. amurensis respond promptly to current-year drought. Under continuously increasing warming conditions, A. mono and B. platyphylla adopted a more "conservative strategy" of reducing the vessel number, size, and density. Populus davidiana showed increased hydraulic safety at the expense of efficiency, while T. amurensis prioritized hydraulic efficiency. Our findings suggest that the ability of these species to persist under future climate scenarios will largely depend on their hydraulic strategies and the balance between growth and water use. Our results contribute to developing forest management practices dealing with preserving ecosystem stability and species diversity of temperate forests in the face of future climate change.

Global warming significantly impacts forest growth. However, commonly used spatially interpolated gridded air temperature datasets may not fully capture these effects due to their coarse spatial resolution and because air temperature may not accurately reflect the conditions that influence the tree growth process. Although finer spatial resolution land surface temperature (LST) datasets may capture more detailed temperature variations, their potential to assess forest growth responses to global warming has not been thoroughly explored. We evaluated the performance of air temperature and LST datasets with various spatial resolutions, including Climatic Research Unit gridded Time Series (CRU), TerraClimate, the land component of the fifth-generation European ReAnalysis (ERA5-Land), and MODIS LST (MOD11A2), in capturing the relationships between tree radial growth and temperature variations across 555 sites in the Northern Hemisphere. Our results showed that the finer spatial resolution MOD11A2 significantly outperformed the widely used CRU air temperature in modeling tree radial growth, with mean and maximum temperatures increasing the coefficient of determination (R2) by 16.32 % and 18.14 %, respectively. This improvement was especially apparent in high-elevation areas where R2 increased by 35.70 % and 36.97 %. We suggested that commonly used spatially interpolated gridded air temperature datasets (e.g., CRU and TerraClimate) may underestimate the impact of rising temperatures on forest growth. Our findings highlight the necessity of integrating high-resolution LST to accurately model forest growth responses to global warming.