Daijun Liu

Genome size (GS) varies widely across plant lineages, yet its ecological consequences remain unclear. Here, we first examined how GS and climatic variables relate to the size of the reproductive unit and biogeochemical niche (i.e., elemental hypervolume) in bryophytes and tracheophytes (vascular plants). GS is positively associated with pollen and seed size in vascular plants but does not influence spore size in bryophytes. Moreover, GS was positively related to elemental flexibility in bryophytes but not in vascular plants, whereas climatic factors showed the opposite pattern. Elemental and climatic hypervolumes are coupled in vascular plants but decoupled in bryophytes. Overall, regardless of whether GS is an adaptive trait or not, GS can impose ecological and physiological constraints through lineage-specific effects on propagule size and physiological flexibility, reflecting the distinct evolutionary pathways followed by bryophytes and vascular plants during the colonization of land.

Mortality, canopy die-off and forest carbon sink decline. Forest adaptation and resistance to drought stress largely rely on hydraulic diversity – the variety and range of hydraulic traits that regulate water use under drought conditions. Yet, how hydraulic diversity emerges within temperate forests and links to forest growth remains poorly resolved. To fill these gaps, we use eight hydraulic traits relating to stomatal closure, structural demand management, water storage, hydraulic resistance and rooting depth to quantify hydraulic diversity within forests, explore how it varies across temperate regions and explore its relationship with forest stem growth using the USA forest inventory data. A total of 31,304 forest plots were aggregated at a 1° grid-cell resolution and hydraulic diversity (721 metacommunities; those with fewer than three tree species are excluded) was quantified as the hypervolume size along the first two axes of principal component analysis (PCA). We found that higher diversity values were observed in the regions of the eastern USA while lower diversity values were found in the western and central USA and boreal regions. The variation in strategy diversity in temperate forests aligns mostly with changes along the acquisitive – conservative axis, spatial hydraulic diversity within temperate forest metacommunities indicates summer precipitation is more crucial than other climate variables. Interestingly, forests with low diversity are widely distributed across the full range of summer precipitation, suggesting that factors beyond water availability – such as temperature – may play an important role, particularly in the Pacific coast of Northern America. Moreover, we observed there is a positive relationship between hydraulic diversity and stem growth across the USA forest metacommunities. Our results provide a foundation for understanding forest hydraulic diversity and improving the accuracy in predicting forest carbon sink potential under a warmer and drier conditions.

Mosquitoes are major vectors of human diseases, and their geographic expansion is primarily driven by the unintentional, human mediated introduction beyond their native ranges. Despite the substantial public health implications and rising numbers of disease outbreaks, a global picture of the introduction trends and the resulting range expansions of mosquitoes is missing. Here, we present a comprehensive and up-to-date compilation and analysis of reported first records of human disease vector mosquitoes worldwide. We show that 45 mosquito species (~25% of those known to transmit human pathogens) have been introduced worldwide, with 28 species having established in at least one region. From the 1950’s onwards, the introduction of new species has increased sharply, with 12 species recorded for the first time outside their native range since 2000 alone. Initially, most introduced species were native to Africa, but over time, Asian species have become more dominant. North America, Australia and Europe remain the main recipients. Our results highlight the role of global trade and transportation in mosquito spread and emphasizes the need for international cooperation to control their spread and potential threat to public health.

Life‐history strategies emerge from eco‐evolutionary constraints, where organisms allocate limited resources to growth, survival, and reproduction, resulting in trade‐offs such as the growth–survival trade‐off. There is still a limited understanding of whether and how disturbance regimes and successional stages might mediate such trade‐offs, with potential consequences for species population dynamics and community assembly. Here, we investigate how disturbances shape the growth–survival trade‐off by comparing early and late‐successional forest stands across the eastern United States. Using large‐scale sampling to capture the realised niche of 68 temperate species, we estimated species‐specific mortality probabilities under zero growth (a proxy for resource‐poor environments) applying a Bayesian multilevel modelling framework. We tested trade‐offs between these estimates and species' maximum growth capacity (a proxy for resource‐rich environments), within and across early and late‐successional stands. Overall, we found a weak growth–survival trade‐off among temperate tree species ( R ² = 0.07). No clear evidence of this trade‐off was found in early successional stands ( R ² = 0.02), while late‐successional stands showed a relatively stronger—though still weak—positive association between species' maximum growth and mortality under zero growth conditions ( R ² = 0.17). Disturbances therefore seem to mediate a filtering of tree life‐history strategies. Consequently, an increase in disturbance rates or changes in their regime could disrupt the growth–survival trade‐off in temperate forests. Synthesis : Life‐history strategies arise from eco‐evolutionary constraints and can lead to trade‐offs like tree growth and survival. While temperate tree species in late‐successional or low‐disturbance‐frequency forests do show a growth–survival trade‐off, this trade‐off is weak and was not found in early successional or high‐disturbance‐frequency stands, nor across all stages combined. Our findings highlight a role of disturbances in filtering life‐history strategies and their potential impact on forest dynamics and global carbon cycling but also a need to better understand the mediating processes of tree demographic trade‐offs.

Summary: Plant biogenic volatile organic compounds (BVOCs) play a critical role in atmospheric chemistry by forming ozone and secondary organic aerosols, making them key agents in regulating air quality and influencing climate. However, current models usually rely on limited site‐specific data and indirect inputs, introducing significant uncertainties in BVOC predictions. We propose remote sensing of photosynthetic optical signals, such as the carotenoid‐sensitive photochemical reflectance index (PRI) and Chl/carotenoid index (CCI) and sun‐induced fluorescence (SIF), to help reduce these uncertainties. These indices are functionally linked, albeit indirectly for SIF, to isoprenoid BVOC emissions via carotenoid biosynthesis. In this Viewpoint, we explore the potential of this connection to estimate and constrain BVOC emissions at multiple scales. We synthesize key aspects, recent advances, and research uncertainties, and propose empirical and scaling roadmaps for integrating optical signals with BVOCs, highlighting their connectivity under abiotic stress (e.g. drought, heat) and across seasonal dynamics. This integration represents a critical step toward reducing model uncertainties, improving large‐scale BVOC monitoring, and enhancing our understanding of their role in atmospheric chemistry and climate. By providing a more comprehensive framework for linking plant physiological processes to atmospheric chemistry, this approach strengthens our ability to predict ecosystem responses to climate change.

Due to climate change, severe-drought events have become increasingly commonplace across Europe in recent decades, with future projections indicating that this trend will likely continue, posing questions about the continued viability of European forests. Observations from the most recent pan-European droughts suggest that these types of “hotter droughts” may acutely alter the carbon balance of European forest ecosystems. However, substantial uncertainty remains regarding the possible future impacts of severe drought on the European forest carbon sink. Dynamic vegetation models can help to shed light on such uncertainties; however, the inclusion of dedicated plant hydraulic architecture modules in these has only recently become more widespread. Such developments intended to improve model performance also tend to add substantial complexity, yet the sensitivity of the models to newly introduced processes is often left undetermined. Here, we describe and evaluate the recently developed mechanistic plant hydraulic architecture version of LPJ-GUESS and provide a parameterization for 12 common European forest tree species. We quantify the uncertainty introduced by the new processes using a variance-based global sensitivity analysis. Additionally, we evaluate the model against water and carbon fluxes from a network of eddy covariance flux sites across Europe. Our results indicate that the new model is able to capture drought-induced patterns of evapotranspiration along an isohydric gradient and manages to reproduce flux observations during drought better than standard LPJ-GUESS does. Further, the sensitivity analysis suggests that hydraulic process related to hydraulic failure and stomatal regulation play the largest roles in shaping the model response to drought.

Summary: Environmental changes and their effects are among the most pressing topics of today's ecological research. Shrublands, although widespread across the globe, remain understudied in this respect. We conducted a global meta‐analysis of 81 shrubland sites subjected to experimental warming, shifts in precipitation (e.g. increased precipitation and drought), and nitrogen addition to quantify seven types of vegetation responses, including density and cover, species diversity, shrub proportion, and ecosystem functions. Our results indicated that the magnitude of responses varied depending on the vegetation metrics and treatment conditions. Specifically, aboveground biomass (AGB) was most sensitive to warming, increased precipitation, and nitrogen addition, while density was most responsive to drought treatment. Short‐term treatments (1–5 yr) generally elicited stronger responses than long‐term ones (> 5 yr), particularly under drought. High sensitivity to changes in climate and nitrogen addition was observed at extremely arid sites (aridity index < 0.2), and water availability strongly mediated sensitivity variation. Surprisingly, many vegetation metrics revealed no association between sensitivity variability and site water availability. Our research offers a global perspective on shrubland vegetation responses to environmental changes, highlighting the importance of water availability in sustaining shrubland biodiversity and functioning under future conditions.

Due to climate change severe drought events have become increasingly commonplace across Europe in recent decades with future projections indicating that this trend will likely continue, posing questions about the continued viability of European forests. Observations from the most recent pan-European droughts suggest that these types of "hotter droughts" may acutely alter the carbon balance of European forest ecosystems. Yet, substantial uncertainty remains regarding the possible future impacts of severe drought on the European forest carbon sink. Dynamic vegetation models can help to shed light on such uncertainties, however, the inclusion of dedicated plant hydraulic architecture modules in these has only recently become more widespread. Such developments intended to improve model performance also tend to add substantial complexity, yet, the sensitivity of the models to newly introduced processes is often left undetermined. Here, we describe and evaluate the recently developed mechanistic plant hydraulic architecture version of LPJ-GUESS and provide a parameterization for 12 common European forest tree species. We quantify the uncertainty introduced by the new processes using a variance-based global sensitivity analysis. Additionally, we evaluate the model against water and carbon fluxes from a network of eddy covariance flux sites across Europe. Our results indicate that the new model is able to capture drought-induced patterns of evapotranspiration along an isohydric gradient and manages to reproduce flux observations during drought better than standard LPJ-GUESS. Further, the sensitivity analysis suggests that hydraulic process related to hydraulic failure and stomatal regulation play the largest roles in shaping model response to drought.

Due to climate change severe drought events have become increasingly commonplace across Europe in recent decades with future projections indicating that this trend will likely continue, posing questions about the continued viability of European forests. Observations from the most recent pan-European droughts suggest that these types of "hotter droughts" may acutely alter the carbon balance of European forest ecosystems. Yet, substantial uncertainty remains regarding the possible future impacts of severe drought on the European forest carbon sink. Dynamic vegetation models can help to shed light on such uncertainties, however, the inclusion of dedicated plant hydraulic architecture modules in these has only recently become more widespread. Such developments intended to improve model performance also tend to add substantial complexity, yet, the sensitivity of the models to newly introduced processes is often left undetermined. Here, we describe and evaluate the recently developed mechanistic plant hydraulic architecture version of LPJ-GUESS and provide a parameterization for 12 common European forest tree species. We quantify the uncertainty introduced by the new processes using a variance-based global sensitivity analysis. Additionally, we evaluate the model against water and carbon fluxes from a network of eddy covariance flux sites across Europe. Our results indicate that the new model is able to capture drought-induced patterns of evapotranspiration along an isohydric gradient and manages to reproduce flux observations during drought better than standard LPJ-GUESS. Further, the sensitivity analysis suggests that hydraulic process related to hydraulic failure and stomatal regulation play the largest roles in shaping model response to drought.