Global increase in the occurrence and impact of multiyear droughts.

Persistent multiyear drought (MYD) events pose a growing threat to nature and humans in a changing climate. We identified and inventoried global MYDs by detecting spatiotemporally contiguous climatic anomalies, showing that MYDs have become drier, hotter, and led to increasingly diminished vegetation greenness. The global terrestrial land affected by MYDs has increased at a rate of 49,279 ± 14,771 square kilometers per year from 1980 to 2018.

The memory of past water abundance shapes trees 7 years later.

Premise: Tree structure and function are constrained by and acclimate to climatic conditions. Drought limits plant growth and carbon acquisition and can result in "legacy" effects that last beyond the period of water stress. Leaf and twig-level legacy effects of past water abundance, such as that experienced by trees that established under wetter conditions are unknown.

Does optimality partitioning theory fail for belowground traits? Insights from geophysical imaging of a drought-release experiment in a Scots Pine forest.

We investigate the impact of a 20-yr irrigation on root water uptake (RWU) and drought stress release in a naturally dry Scots pine forest. We use a combination of electrical resistivity tomography to image RWU, drone flights to image the crown stress and sensors to monitor soil water content. Our findings suggest that increased water availability enhances root growth and resource use efficiency, potentially increasing trees' resistance to future drought conditions by enabling water uptake from deeper soil layers.

Stable Isotope Labelling Reveals Water and Carbon Fluxes in Temperate Tree Saplings Before Budbreak.

Despite considerable experimental effort, the physiological mechanisms governing temperate tree species' water and carbon dynamics before the onset of the growing period remain poorly understood. We applied H-enriched water during winter dormancy to the soil of four potted European tree species. After 8 weeks of chilling, hydrogen isotopes in stem, twig and bud water were measured six times during 2 consecutive weeks of forcing conditions (Experiment 1).

Dry inside: progressive unsaturation within leaves with increasing vapour pressure deficit affects estimation of key leaf gas exchange parameters.

Climate change not only leads to higher air temperatures but also increases the vapour pressure deficit (VPD) of the air. Understanding the direct effect of VPD on leaf gas exchange is crucial for precise modelling of stomatal functioning. We conducted combined leaf gas exchange and online isotope discrimination measurements on four common European tree species across a VPD range of 0.

Green Routes: Exploring Protein-Based Virus-like Nanoparticle Transport and Immune Activation in for Biotechnological Applications.

Viral, bacterial, fungal, and nematode infections cause significant agricultural losses, with limited treatment options, necessitating novel approaches to enhance plant defense systems and protection against pathogens. Virus-like nanoparticles (VLPs), extensively used in animal and human therapies (e.g.

Hydrogen isotope fractionation in plants with C, C, and CAM CO fixation.

Measurements of stable isotope ratios in organic compounds are widely used tools for plant ecophysiological studies. However, the complexity of the processes involved in shaping hydrogen isotope values (δH) in plant carbohydrates has limited its broader application. To investigate the underlying biochemical processes responsible for H fractionation among water, sugars, and cellulose in leaves, we studied the three main CO fixation pathways (C, C, and CAM) and their response to changes in temperature and vapor pressure deficit (VPD).

Uptake and physiological impacts of nanoplastics in trees with divergent water use strategies.

Anthropogenic contaminants can place significant stress on vegetation, especially when they are taken up into plants. Plastic pollution, including nanoplastics (NPs), could be detrimental to tree functioning, by causing, for example, oxidative stress or reducing photosynthesis. While a number of studies have explored the capacity of plants to take up NPs, few have simultaneously assessed the functional damage due to particulate matter uptake.

The marriage between stable isotope ecology and plant metabolomics - new perspectives for metabolic flux analysis and the interpretation of ecological archives.

Even though they share many thematical overlaps, plant metabolomics and stable isotope ecology have been rather separate fields mainly due to different mass spectrometry demands. New high-resolution bioanalytical mass spectrometers are now not only offering high-throughput metabolite identification but are also suitable for compound- and intramolecular position-specific isotope analysis in the natural isotope abundance range. In plant metabolomics, label-free metabolic pathway and metabolic flux analysis might become possible when applying this new technology.

Legacy effects of premature defoliation in response to an extreme drought event modulate phytochemical profiles with subtle consequences for leaf herbivory in European beech.

Extreme droughts can have long-lasting effects on forest community dynamics and species interactions. Yet, our understanding of how drought legacy modulates ecological relationships is just unfolding. We tested the hypothesis that leaf chemistry and herbivory show long-term responses to premature defoliation caused by an extreme drought event in European beech (Fagus sylvatica L.

Different responses of oxygen and hydrogen isotopes in leaf and tree-ring organic matter to lethal soil drought.

The oxygen and hydrogen isotopic composition (δ18O, δ2H) of plant tissues are key tools for the reconstruction of hydrological and plant physiological processes and may therefore be used to disentangle the reasons for tree mortality. However, how both elements respond to soil drought conditions before death has rarely been investigated. To test this, we performed a greenhouse study and determined predisposing fertilization and lethal soil drought effects on δ18O and δ2H values of organic matter in leaves and tree rings of living and dead saplings of five European tree species.

Species-specific responses of C and N allocation to N addition: evidence from dual C and N labeling in three tree species.

Soil nitrogen (N) availability affects plant carbon (C) utilization. However, it is unclear how various tree functional types respond to N addition in terms of C assimilation, allocation, and storage. Here, a microcosm experiment with dual C and N labeling was conducted to study the effects of N addition (i.

The metabolic fingerprint of Scots pine-root and needle metabolites show different patterns in dying trees.

The loss of leaves and needles in tree crowns and tree mortality are increasing worldwide, mostly as a result of more frequent and severe drought stress. Scots pine (Pinus sylvestris L.) is a tree species that is strongly affected by these developments in many regions of Europe and Asia.

Fungal community composition predicts forest carbon storage at a continental scale.

Forest soils harbor hyper-diverse microbial communities which fundamentally regulate carbon and nutrient cycling across the globe. Directly testing hypotheses on how microbiome diversity is linked to forest carbon storage has been difficult, due to a lack of paired data on microbiome diversity and in situ observations of forest carbon accumulation and storage. Here, we investigated the relationship between soil microbiomes and forest carbon across 238 forest inventory plots spanning 15 European countries.

Finding balance: Tree-ring isotopes differentiate between acclimation and stress-induced imbalance in a long-term irrigation experiment.

Scots pine (Pinus sylvestris L.) is a common European tree species, and understanding its acclimation to the rapidly changing climate through physiological, biochemical or structural adjustments is vital for predicting future growth. We investigated a long-term irrigation experiment at a naturally dry forest in Switzerland, comparing Scots pine trees that have been continuously irrigated for 17 years (irrigated) with those for which irrigation was interrupted after 10 years (stop) and non-irrigated trees (control), using tree growth, xylogenesis, wood anatomy, and carbon, oxygen and hydrogen stable isotope measurements in the water, sugars and cellulose of plant tissues.

Stable water isotopes reveal the onset of bud dormancy in temperate trees, whereas water content is a better proxy for dormancy release.

Earlier spring growth onset in temperate forests is a visible effect of global warming that alters global water and carbon cycling. Consequently, it becomes crucial to accurately predict the future spring phenological shifts in vegetation under different climate warming scenarios. However, current phenological models suffer from a lack of physiological insights of tree dormancy and are rarely experimentally validated.

Why leaves become isotopically lighter than photosynthetic carbon isotope discrimination explains: on the importance of post-photosynthetic fractionation.

This article comments on: Yu YZ, Liu HT, Yang F, Li L, Schäufele R, Tcherkez G, Schnyder H, Gong XY. 2024. δC of bulk organic matter and cellulose reveal post-photosynthetic fractionation during ontogeny in C grass leaves.

Contrasting physiological strategies explain heterogeneous responses to severe drought conditions within local populations of a widespread conifer.

Understanding how trees prioritize carbon gain at the cost of drought vulnerability under severe drought conditions is crucial for predicting which genetic groups and individuals will be resilient to future climate conditions. In this study, we investigated variations in growth, tree-ring anatomy as well as carbon and oxygen isotope ratios to assess the sensitivity and the xylem formation process in response to an episode of severe drought in 29 mature white spruce (Picea glauca [Moench] Voss) families grown in a common garden trial. During the drought episode, the majority of families displayed decreased growth and exhibited either sustained or increased intrinsic water-use efficiency (iWUE), which was largely influenced by reduced stomatal conductance as revealed by the dual carbon‑oxygen isotope approach.

Drought resistance and resilience of rhizosphere communities in forest soils from the cellular to ecosystem scale - insights from C pulse labeling.

The link between above- and belowground communities is a key uncertainty in drought and rewetting effects on forest carbon (C) cycle. In young beech model ecosystems and mature naturally dry pine forest exposed to 15-yr-long irrigation, we performed C pulse labeling experiments, one during drought and one 2 wk after rewetting, tracing tree assimilates into rhizosphere communities. The C pulses applied in tree crowns reached soil microbial communities of the young and mature forests one and 4 d later, respectively.

Forest demography and biomass accumulation rates are associated with transient mean tree size vs. density scaling relations.

Linking individual and stand-level dynamics during forest development reveals a scaling relationship between mean tree size and tree density in forest stands, which integrates forest structure and function. However, the nature of this so-called scaling law and its variation across broad spatial scales remain unquantified, and its linkage with forest demographic processes and carbon dynamics remains elusive. In this study, we develop a theoretical framework and compile a broad-scale dataset of long-term sample forest stands ( = 1,433) from largely undisturbed forests to examine the association of temporal mean tree size vs.

Beyond source and sink control - toward an integrated approach to understand the carbon balance in plants.

A conceptual understanding on how the vegetation's carbon (C) balance is determined by source activity and sink demand is important to predict its C uptake and sequestration potential now and in the future. We have gathered trajectories of photosynthesis and growth as a function of environmental conditions described in the literature and compared them with current concepts of source and sink control. There is no clear evidence for pure source or sink control of the C balance, which contradicts recent hypotheses.