Forests are increasingly impacted by climate change, affecting tree growth and carbon sequestration. Tree-ring width, closely related to tree growth, is a key climate proxy, yet models describing ring width or growth often lack comprehensive environmental data. This study assesses ERA5-Land data for tree-ring width prediction compared to automatic weather station observations, emphasizing the value of extended and global climate data. We analyzed 723 site-averaged and detrended tree-ring chronologies from two broadleaved and two gymnosperm species across Europe, integrating them with ERA5-Land climate data, CO2 concentration, and a drought index (SPEI12). A subset was compared with weather station data. For modelling interannual variations of tree-ring width we used linear models to assess parameter importance. ERA5-Land and weather-station-based models performed similarly, maintaining stable correlations and consistent errors. Models based on meteorological data from weather stations highlighted SPEI12, sunshine duration, and temperature extremes, while ERA5-Land models emphasized SPEI12, dew-point temperature (humidity), and total precipitation. CO2 positively influenced the growth of gymnosperm species. ERA5-Land facilitated broader spatial analysis and incorporated additional factors like evaporation, snow cover, and soil moisture. Monthly assessments revealed the importance of parameters for each species. Our findings confirm that ERA5-Land is a reliable alternative for modeling tree growth, offering new insights into climate-vegetation interactions. The ready availability of underutilized parameters, such as air humidity, soil moisture and temperature, and runoff, enables their inclusion in future growth models. Using ERA5-Land can therefore deepen our understanding of forest responses to diverse environmental drivers on a global scale.

Tree destruction induced by heavy rainfall, an overlooked type of forest degradation, has been exacerbated along with global climate change. On the Chinese Loess Plateau, especially in afforested gully catchments dominated by Robinia pseudoacacia, destructive rainfall events have increasingly led to widespread forest damage. Previous study has manifested the severity of heavy rainfall-induced tree destruction and its association with topographic change, yet the contributions of tree structure and forest structure remain poorly understood. In this study, we quantified the destroyed trees induced by heavy rainfall using light detection and ranging (LiDAR) techniques. We assessed the influence of tree structure (tree height, crown diameter, and crown area), forest structure (tree density, gap fraction, leaf area index, and canopy cover), and terrain parameters (elevation, slope, and terrain relief) using machine learning models (random forest and logistic regression). Based on these, we aimed to clarify the respective and combined contributions of structural and topographic factors to rainfall-induced tree destruction. Key findings revealed that when considered in isolation, greater tree height, crown diameter, crown area, leaf area index (LAI), and canopy cover suppressed tree destruction, whereas higher gap fractions increased the probability of tree destruction. However, the synergistic increases of tree structural factors (tree height, crown diameter, and crown area) and forest structural factors (LAI and canopy cover) significantly promoted tree destruction, which can counteract the inhibitory effect of terrain on destruction. In addition, increases in tree structure or canopy density (LAI and canopy cover) also increased the probability of tree destruction at the same elevation. Our findings challenge conventional assumptions in forest management by demonstrating the interaction of tree structure and canopy density can significantly promote tree destruction during heavy rainfall. This highlights the need to avoid overly dense afforestation in vulnerable landscapes and supports more adaptive, climate-resilient restoration strategies.

Increasing drought stress due to climate warming has triggered various negative impacts on plantations in dryland areas, including growth reduction, crown dieback, and even tree mortality, with unavoidable consequences for forest ecosystems. However, how drought stress progressively led to the damage process from growth reduction to mortality for mature trees remains largely unclear, especially its varying soil moisture thresholds. Here we selected mature trees in larch (Larix principis-rupprechtii) plantations in the dryland areas of northwest China, and monitored the progressive tree responses in an extreme summer drought event in 2021, including transpiration, radial growth, leaf area index, discoloration, defoliation, crown dieback and tree mortality. The results showed strong responses of larch trees to summer drought, such as large stem shrinkage, dramatic decrease in transpiration and leaf area index, and obvious discoloration, defoliation, crown dieback and tree mortality at some sites. The intensity of tree responses mainly depended on soil moisture rather than meteorological factors and there were strong relationships between tree responses and relative soil water content (RSW) of 0-60 cm layers. Based on the trees responded to RSW, five soil drought stress levels or progressive mortality stages and their corresponding RSW thresholds were determined as following: no detectable hydraulic limitations (RSW>0.7, Level I), persistent stem shrinkage and onset of transpiration reduction (0.45<= 0.7, Level II), onset of slight discoloration and defoliation (0.35<= 0.45, Level III), onset of crown dieback and tree mortality (0.25<= 0.35, Level IV), and severe defoliation, crown dieback and tree mortality (RSW <= 0.25, Level V). This study showed that the trees responded to climatic drought were strongly regulated by soil moisture and thus were strongly site-specific. These findings will help to evaluate the degree and spatio-temporal distribution of tree damage and mortality in plantations under increasing climatic drought, particularly in dryland areas.

Soil creep is a slow type of mass movement that, despite its low velocity, can significantly influence slope stability and landscape evolution over time. Understanding its mechanisms and spatial variability is essential for assessing slope stability. However, obtaining high-quality long-term data on creep activity remains a challenge. Dendrogeomorphic methods offer a promising approach to reconstruct past creep movements, but their application to shallow creep processes still requires further refinement. Therefore, this research undertakes a dendrogeomorphic analysis of shallow creep movements on flysch rock slopes, utilizing tree-ring eccentricity as an indicator of this geomorphic process. A total of 136 increment cores from 68 Norway spruce (Picea abies (L.) H. Karst.) trees were analysed, revealing the spatio-temporal dynamics of shallow creep and its relationship with slope morphometry and weathering mantle thickness. The eccentricity values were spatially interpolated to visualize the evolution of creep activity over decades, which showed its significant spatial variability. Statistical analyses, including Pearson's and Spearman's correlation coefficients, were employed to examine the relationships between tree-ring eccentricity and various environmental factors. Results indicated that tree age influences the sensitivity to creep signals, with older trees showing increased eccentricity, suggesting a heightened response to creep movements. The study also explored the impact of precipitation on creep activity, identifying a weak, non-significant positive relationship. This comprehensive analysis enhances the understanding of shallow creep mechanisms and contributes to the broader field of dendrogeomorphology.

Tree architecture is an important component of forest community dynamics - taller trees with larger crowns often outcompete their neighbors, but they are generally at higher risk of wind-induced damage. Yet, we know little about wind impacts on tree architecture in natural forest settings, especially in complex tropical forests. Here, we use airborne light detection and ranging (LiDAR) and 30 yr of forest inventory data in Puerto Rico to ask whether and how chronic winds alter tree architecture. We randomly sampled 124 canopy individuals of four dominant tree species (n = 22-39). For each individual, we measured slenderness (height/stem diameter) and crown area (m2) and evaluated whether exposure to chronic winds impacted architecture after accounting for topography (curvature, elevation, slope, and soil wetness) and neighborhood variables (crowding and previous hurricane damage). We then estimated the mechanical wind vulnerability of trees. Three of four species grew significantly shorter (2-4 m) and had smaller crown areas in sites exposed to chronic winds. A short-lived pioneer species, by contrast, showed no evidence of wind-induced changes. We found that three species' architectural acclimation to chronic winds resulted in reduced vulnerability. Our findings demonstrate that exposure to chronic, nonstorm winds can lead to architectural changes in tropical trees, reducing height and crown areas. La arquitectura de los & aacute;rboles es un componente importante de la din & aacute;mica de la comunidad forestal: los & aacute;rboles m & aacute;s altos con copas m & aacute;s grandes suelen sobrepasar a sus vecinos, pero por lo general corren m & aacute;s riesgo de sufrir da & ntilde;os inducidos por el viento. Sin embargo, es poco lo que se sabe sobre el impacto del viento en la arquitectura de los & aacute;rboles en entornos forestales naturales, sobre todo en bosques tropicales complejos. En este caso, utilizamos LiDAR y 30 a & ntilde;os de datos de campo en Puerto Rico para preguntarnos si los vientos cr & oacute;nicos alteran la arquitectura de los & aacute;rboles. Se tom & oacute; una muestra aleatoria de 124 individuos del dosel de cuatro especies arb & oacute;reas dominantes (n = 22-39). De cada individuo, medimos la esbeltez (altura/di & aacute;metro) y el & aacute;rea de la copa (m2) y evaluamos si la exposici & oacute;n a vientos cr & oacute;nicos influ & iacute;a en la arquitectura teniendo en cuenta la topograf & iacute;a (curvatura, elevaci & oacute;n, pendiente, humedad del suelo) y las variables del vecindario (aglomeraci & oacute;n y da & ntilde;os previos por huracanes). Luego, estimamos la vulnerabilidad mec & aacute;nica de los & aacute;rboles al viento. En los lugares expuestos a vientos cr & oacute;nicos, tres de las cuatro especies crecieron mucho menos (2-4 m) y tuvieron & aacute;reas de copa m & aacute;s peque & ntilde;as. Cecropia schreberiana, en cambio, no mostr & oacute; indicios de cambios inducidos por el viento. La aclimataci & oacute;n arquitect & oacute;nica de tres especies a los vientos cr & oacute;nicos llevaba a una reducci & oacute;n de la vulnerabilidad. Nuestros hallazgos demuestran que la exposici & oacute;n a vientos cr & oacute;nicos puede provocar cambios arquitect & oacute;nicos en los & aacute;rboles tropicales, reduciendo su altura y la superficie de sus copas.

AimsPecan (Carya cathayensis Sarg.) is an important forest trees in China, the application of chemical pesticides for disease control has caused severe damage to the soil, including reduced fertility and disruption of microbial communities. Although Trichoderma treatment has been shown to promote plant growth and improve soil quality, its effects on the growth promotion of pecan and the impact on soil microbial communities and physicochemical properties remained unclear.MethodsIn this study, we investigated the impact of T. asperellum TCS007 spore suspension and its fermented crude extract on the growth and development of pecan seedlings. We also explored the effects of TCS007 treatment on the nutrients, enzyme activities, and microbial diversity in the rhizosphere soil of pecan seedlings during their three main growth stages.ResultsTreatment with TCS007 spore suspension or crude extract promoted the growth of pecan seedlings, with significantly higher levels of leaf hormones and defense enzyme activity compared to the control (CK). Moreover, the content of soil organic matter and ammonium nitrogen, as well as the activity of soil enzymes such as catalase and urease, were all significantly higher than CK after treatment, and the soil pH shifted from slightly acidic to slightly alkaline. The results indicated that TCS007 treatment significantly increased the richness of beneficial fungi and bacteria in the soil.ConclusionThe results demonstrated that TCS007 treatment significantly promoted the growth of pecan plants, increased enzyme activity and nutrient content in the soil, and improved the soil micro-ecological environment.

Alpine treelines ecotones are critical ecological transition zones and are highly sensitive to global warming. However, the impact of climate on the distribution of treeline trees is not yet fully understood as this distribution may also be affected by other factors. Here, we used high-resolution satellite images with climatic and topographic variables to study changes in treeline tree distribution in the alpine treeline ecotone of the Changbai Mountain for the years 2002, 2010, 2017, and 2021. This study employed the Geodetector method to analyze how interactions between climatic and topographic factors influence the expansion of Betula ermanii on different aspect slopes. Over the past 20 years, B. ermanii, the only tree species in the Changbai Mountain tundra zone, had its highest expansion rate from 2017 to 2021 across all the years studied, approaching 2.38% per year. In 2021, B. ermanii reached its uppermost elevations of 2224 m on the western aspects and 2223 m on the northern aspects, which are the predominant aspects it occupies. We also observed a notable increase in the distribution of B. ermanii on steeper slopes (> 15 degrees) between 2002 and 2021. Moreover, we found that interactions between climate and topographic factors played a more significant role in B. ermanii's expansion than any single dominant factor. Our results suggest that the interaction between topographic wetness index and the coldest month precipitation (Pre(1)), contributing 91% of the observed variability, primarily drove the expansion on the southern aspect by maintaining soil moisture, providing snowpack thermal insulation which enhanced soil temperatures, decomposition, and nutrient release in harsh conditions. On the northern aspect, the interaction between elevation and mean temperature of the warmest month explained 80% of the expansion. Meanwhile, the interaction between Pre(1) and mean temperature of the growing season explained 73% of the expansion on the western aspect. This study revealed that dominant factors driving treeline upward movement vary across different mountain aspects. Climate and topography play significant roles in determining tree distribution in the alpine treeline ecotone. This knowledge helps better understand and forecast treeline dynamics in response to global climate change.

Superabsorbent nanocomposite hydrogels based on polyacrylamide (PAAm), cashew tree gum (CG), and laponite (LAP) were synthesized in different concentrations to investigate swelling, thermal, morphological and rheological properties. Vibrational modes confirmed the formation of hydrogels, while X-ray diffraction patterns reveal the semi-crystalline structure of the hydrogels. Thermal analysis showed that higher LAP content and CGLAP interactions improved the thermal stability of the hydrogels. Morphology analysis presented porous structures in CG-based hydrogels, contrasting with irregular plate-like structures in those without CG. The swelling capacity had better results in hydrogels with CG that were subjected to alkaline hydrolysis, mainly in a buffer solution with a pH > 4, due to the ionization of the hydrophilic groups. Hydrogels containing LAP maintained swelling degree stability at pH 10 and 12. In rheological tests, the addition of LAP increased the viscosity of the hydrogels, significantly improving the mechanical resistance of the hydrogels. Rheological parameters, such as the storage modulus (G ') and loss modulus (G ''), indicated that the materials exhibited predominantly solid behavior, particularly in CG-LAP-rich hydrogels. Low mortality of Artemia salina nauplii in toxicity tests confirmed material safety. The results indicate that CG-LAP hydrogels are promising for agricultural applications, offering optimized swelling properties, thermal stability, and mechanical strength.

The study applies the Minimum Impact Design Standards (MIDS) calculator to assess urban trees' effectiveness in reducing surface runoff along five flood-prone streets in Hue City, analyzing evapotranspiration, rainfall interception, and infiltration, along with Leaf Area Index (LAI), Canopy Projection (CP), tree pit size, and soil structure. Results show that urban trees retain 1,132.39 m(3) of stormwater, but runoff reduction is not solely dependent on tree quantity. Although tree numbers vary 1.56 to 3.8 times, runoff reduction differs only 1.39 to 1.79 times. Evapotranspiration plays the largest role, contributing 2.8 times more than interception and 2.6 times more than infiltration. Small tree pits and compacted soil limit infiltration, while pruning and height reduction decrease Pc and LAI, reducing flood mitigation benefits. Annual storm damage further weakens this capacity. To enhance effectiveness, the study suggests prioritizing storm-resistant species, increasing tree numbers, enlarging tree pits, and using structured soil. Implementing these measures can improve urban flood resilience and maximize trees' hydrological benefits. Future research should focus on optimizing tree selection and planting strategies for long-term flood management in urban areas, ensuring sustainable solutions that enhance both stormwater control and environmental resilience.

With global warming, the frequency and intensity of drought episodes are projected to increase worldwide, especially in the boreal forest. This represents a serious threat to the boreal forest ecosystem's productivity and environmental services. It is thus crucial to better understand how drought or water limitation could affect boreal forest ecosystems functioning, and to be prepared to overcome damage caused by drought events. Studies suggest that microbes may mitigate the negative effects of drought or water shortage on plants. However, most of these studies focused on soil microbes and on agricultural ecosystems. Here, we used a rainout shelters and soil irrigation experimental design to study the response to rain exclusion and soil water content of epiphytic phyllosphere bacterial communities associated with four boreal conifer tree species. Our results showed only a weak response of phyllosphere bacterial communities to variation in soil water content. On the other hand, host tree species identity and rain exclusion were the main drivers of epiphytic phyllosphere bacterial communities' structure and diversity. This suggests that fewer rain events, in the context of climate change, would impact boreal trees phyllosphere microbiome composition.