Multiple climate change stressors reduce the emergence success of gravel-spawning fish species and alter temporal emergence patterns.

Climate change, with its profound effects on stream sediment, hydrological, and temperature dynamics, will exacerbate impacts on habitat conditions for many species, particularly those with vulnerable early life stages relying on the hyporheic zone, such as gravel-spawning fishes. Due to the complex and interactive nature of multiple stressor effects, we employed large-scale outdoor mesocosms to systemically test how the reproductive success of three gravel-spawning fish species brown trout (Salmo trutta), nase, (Chrondrostoma nasus) and Danube salmon (Hucho hucho) was affected by individual and combined effects of warming (+3-4 °C), fine sediment (increase in <0.85 mm by 22 %) and low-flow (eightfold discharge-reduction). Fine sediment had the most detrimental effect on emergence rate and fry length in all three species, reducing the emergence rate to zero in brown trout, 9 % in nase, and 4 % in Danube salmon. The emergence mortality caused by fine sediment surpassed that of hatching distinctly, suggesting that negative effects due to hypoxia were considerably exacerbated by entombment. Warming had only minor effects as a single stressor, but low flow reduced emergence rates of the spring spawning species nase and Danube salmon by 8 and 50 %, respectively. In combined treatments including fine sediment, however, the emergence success of all three species responded strongly negatively, even in the cyprinid species nase, which showed little interactive effects between stressors regarding hatching success. Warming and fine sediment also led to the earlier emergence of fry, implying a risk of asynchrony with available food resources. This study dramatically shows that climate change can have deleterious impacts on the reproductive success of gravel-spawning fish species, irrespective of taxonomic or ecological traits.

Climate change increases flowering duration, driving phenological reassembly and elevated co-flowering richness.

Changes to flowering phenology are a key response of plants to climate change. However, we know little about how these changes alter temporal patterns of reproductive overlap (i.e. phenological reassembly). We combined long-term field (1937-2012) and herbarium records (1850-2017) of 68 species in a flowering plant community in central North America and used a novel application of Bayesian quantile regression to estimate changes to flowering season length, altered richness and composition of co-flowering assemblages, and whether phenological shifts exhibit seasonal trends. Across the past century, phenological shifts increased species' flowering durations by 11.5 d on average, which resulted in 94% of species experiencing greater flowering overlap at the community level. Increases to co-flowering were particularly pronounced in autumn, driven by a greater tendency of late season species to shift the ending of flowering later and to increase flowering duration. Our results demonstrate that species-level phenological shifts can result in considerable phenological reassembly and highlight changes to flowering duration as a prominent, yet underappreciated, effect of climate change. The emergence of an autumn co-flowering mode emphasizes that these effects may be season-dependent.

Bioindicator aquatic insects at risk from climate change in a biodiversity hotspot.

Climate change can affect biological assemblages by shifting their species' geographic range and changing species richness. Aquatic insects represent more than half of the freshwater animal species but have been neglected mainly in climate change assessments, particularly in tropical ecosystems. Among the aquatic insect taxa, Ephemeroptera, Plecoptera, and Trichoptera (EPT) are well-known bioindicators of environmental changes and encompass an essential metric for rivers and streams' biomonitoring. Here, we use ecological niche models to project the impact of climate change on the distribution range and richness of EPT in the Atlantic Forest biodiversity hotspot. We found EPT to be at high risk from future climate change, with Plecoptera as the order of greatest concern. We projected range contraction of ca. 90 % of the analyzed EPT genera, resulting in a reduction in the richness of EPT genera under future climatic conditions. We projected >50 % contraction in the distribution of 50 % of Plecoptera, ≈14 % of Trichoptera, and ≈7 % of Ephemeroptera genera. The remaining climatically suitable regions in the Atlantic Forest are concentrated in the high-altitude areas, which may act as climate refuges for EPT biodiversity in the future. The projected changes in EPT's distribution range and richness may impact biomonitoring programs conducted in tropical ecosystems. Restricting EPT's geographic distribution may undermine its potential as a bioindicator and influence the composition of EPT assemblages at reference sites, which may lead to shifting baseline conditions. We reinforce the importance of considering future climatic conditions when planning long-term biomonitoring and priority areas for conservation.

Prediction of future microplastic accumulation in agricultural soils.

This study shows the general exponential rise in microplastic accumulation in agricultural soils, with fertilizer application speeding up this increase, and future predictions of microplastic concentrations. Utilizing data from the Broadbalk winter wheat experiment at Rothamsted Research, UK, from 1846 to 2022, Poisson regression models were applied to microplastic counts under different soil treatments, including farmyard manure, inorganic fertilizers, and control conditions. A mass conversion factor was applied to obtain the w/w relationship. Results indicated a significant annual increase in microplastic concentrations across all treatments, with fertilized soils showing a notably higher accumulation rate. Our study forecasts that, in 50 and 100 years from now, soils treated with fertilizers are expected to reach microplastic concentrations of 168.9 mg kg-1 (95% CI: 60.32-473.09) and 1159 mg kg-1 (95% CI: 200.49-6699.8) respectively, levels converging on those used in many experiments. This highlights the urgent need for strategies to mitigate microplastic pollution in agricultural fields. The results also help to choose predicted concentrations in global change experiments, as well as to motivate further research to explore the mechanisms of microplastic accumulation and the integration of these insights into broader agricultural and ecological models to guide sustainable practices and environmental conservation.

Forest floor environment overrules global change treatment effects on understorey communities in a mesocosm experiment.

Light availability profoundly influences plant communities, especially below dense tree canopies in forests. Canopy disturbances, altering forest floor light conditions, together with other environmental changes such as climate change, nitrogen deposition and legacy effects from previous land-use will simultaneously impact forest understorey communities. Yet, knowledge on the individual effects of these drivers and their potential interactions remains scarce. Here we performed a forest mesocosm experiment to assess the influence of warming, illumination (simulating canopy opening), nitrogen deposition and soil land-use history (comparing ancient and post-agricultural forest soil) on understorey community composition trajectories over a 7-year period. Strikingly, understorey communities primarily evolved in response to the deeply shaded ambient forest conditions, with experimental treatments exerting only secondary influences. The overruling trajectory steered all mesocosms towards slow-colonizing forest specialist communities dominated by spring geophytes with lower nutrient-demand. The illumination treatment and, to a lesser extent, warming and agricultural land-use legacy slowed down this trend by advancing fast-growing resource-acquisitive generalist species. Warm ambient temperatures induced thermophilization of plant communities in all treatments, including control plots, towards higher dominance of warm-adapted species. Nitrogen addition accelerated this thermophilization process and increased the community light-demand signature. Land-use legacy effects were limited in our study. Our findings underscore the essential role of limited light availability in preserving forest specialists in understorey communities and highlight the importance of maintaining a dense canopy cover to attenuate global change impacts. It is crucial to integrate this knowledge in forest management adaptation to global change, particularly in the face of increasing demands for wood and wood products and intensified natural canopy disturbances.

Mycorrhization enhances plant growth and stabilizes biomass allocation under drought.

Plants and their symbionts, such as arbuscular mycorrhizal (AM) fungi, are increasingly subjected to various environmental stressors due to climate change, including drought. As a response to drought, plants generally allocate more biomass to roots over shoots, thereby facilitating water uptake. However, whether this biomass allocation shift is modulated by AM fungi remains unknown. Based on 5691 paired observations from 154 plant species, we conducted a meta-analysis to evaluate how AM fungi modulate the responses of plant growth and biomass allocation (e.g., root-to-shoot ratio, R/S) to drought. We found that AM fungi attenuate the negative impact of drought on plant growth, including biomass production, photosynthetic performance and resource (e.g. nutrient and water) uptake. Accordingly, drought significantly increased R/S in non-inoculated plants, but not in plants symbiotic with established AM fungal symbioses. These results suggest that AM fungi promote plant growth and stabilize their R/S through facilitating nutrient and water uptake in plants under drought. Our findings highlight the crucial role of AM fungi in enhancing plant resilience to drought by optimizing resource allocation. This knowledge opens avenues for sustainable agricultural practices that leverage symbiotic relationships for climate adaptation.

Shipping traffic through the Arctic Ocean: Spatial distribution, seasonal variation, and its dependence on the sea ice extent.

The reduction in sea ice cover with Arctic warming facilitates shipping through remarkably shorter shipping routes. Automatic identification system (AIS) is a powerful data source to monitor Arctic Ocean shipping. Based on the AIS data from an online platform, we quantified the spatial distribution of shipping through this area, its intensity, and the seasonal variation. Shipping was heterogeneously distributed with power-law exponents that depended on the vessel category. We contextualized the estimated exponents with the analytical distribution of a transit model in one and two dimensions. Fishing vessels had the largest spatial spread, while narrower shipping routes associated with cargo and tanker vessels had a width correlated with the sea ice area. The time evolution of these routes showed extended periods of shipping activity through the year. We used AIS data to quantify recent Arctic shipping, which brings an opportunity for shorter routes, but likely impacting the Arctic ecosystem.

Land use modulates resistance of grasslands against future climate and inter-annual climate variability in a large field experiment.

Climate and land-use change are key drivers of global change. Full-factorial field experiments in which both drivers are manipulated are essential to understand and predict their potentially interactive effects on the structure and functioning of grassland ecosystems. Here, we present 8 years of data on grassland dynamics from the Global Change Experimental Facility in Central Germany. On large experimental plots, temperature and seasonal patterns of precipitation are manipulated by superimposing regional climate model projections onto background climate variability. Climate manipulation is factorially crossed with agricultural land-use scenarios, including intensively used meadows and extensively used (i.e., low-intensity) meadows and pastures. Inter-annual variation of background climate during our study years was high, including three of the driest years on record for our region. The effects of this temporal variability far exceeded the effects of the experimentally imposed climate change on plant species diversity and productivity, especially in the intensively used grasslands sown with only a few grass cultivars. These changes in productivity and diversity in response to alterations in climate were due to immigrant species replacing the target forage cultivars. This shift from forage cultivars to immigrant species may impose additional economic costs in terms of a decreasing forage value and the need for more frequent management measures. In contrast, the extensively used grasslands showed weaker responses to both experimentally manipulated future climate and inter-annual climate variability, suggesting that these diverse grasslands are more resistant to climate change than intensively used, species-poor grasslands. We therefore conclude that a lower management intensity of agricultural grasslands, associated with a higher plant diversity, can stabilize primary productivity under climate change.

Increased ecological land and atmospheric CO2 dominate the growth of ecosystem carbon sinks under the regulation of environmental conditions in national key ecological function zones in China.

Increased ecological land (IEL) such as forests and grasslands can greatly enhance ecosystem carbon sinks. Understanding the mechanisms for the magnitude of IEL-induced ecosystem carbon sinks is crucial for achieving carbon neutrality. We estimated the impact of IEL, specifically the increase in forests and grasslands, as well as global changes including atmospheric CO2 concentration, nitrogen deposition, and climate change on net ecosystem productivity (NEP) in National Key Ecological Function Zones (NKEFZs) in China using a calibrated ecological process model. The NEP in NKEFZs in China was calculated to be 119.4 Tg C yr-1, showing an increase of 42.6 Tg C yr-1 from 2001 to 2021. Compared to the slight contributions of climate change (-8.0%), nitrogen deposition (11.5%), and reduction in ecological land (-3.5%), the increase in NEP was primarily attributed to CO2 (66.5%) and IEL (33.5%). Moreover, the effect of IEL (14.8 Tg C yr-1) surpassed that of global change (13.1 Tg C yr-1) in the land use change zone. The IEL-induced NEP is significantly associated with CO2 fertilization, regulated by precipitation and nitrogen deposition. The high values of IEL-induced NEP occurred in areas with precipitation exceeding 800 mm and nitrogen deposition exceeding 25 kg N ha-1 yr-1. We recommend prioritizing the expansion of ecological land in areas with sufficient water and nutrients to enhance CO2 fertilization, while avoiding increasing ecological land in regions facing unfavorable climate change conditions. This study serves as a foundation for comprehending the NEP response to ecological restoration and global change.

Arbuscular mycorrhizal fungi attenuate negative impact of drought on soil functions.

Although positive effects of arbuscular mycorrhizal (AM) fungi on plant performance under drought have been well documented, how AM fungi regulate soil functions and multifunctionality requires further investigation. In this study, we first performed a meta-analysis to test the potential role of AM fungi in maintaining soil functions under drought. Then, we conducted a greenhouse experiment, using a pair of hyphal ingrowth cores to spatially separate the growth of AM fungal hyphae and plant roots, to further investigate the effects of AM fungi on soil multifunctionality and its resistance against drought. Our meta-analysis showed that AM fungi promote multiple soil functions, including soil aggregation, microbial biomass and activities of soil enzymes related to nutrient cycling. The greenhouse experiment further demonstrated that AM fungi attenuate the negative impact of drought on these soil functions and thus multifunctionality, therefore, increasing their resistance against drought. Moreover, this buffering effect of AM fungi persists across different frequencies of water supply and plant species. These findings highlight the unique role of AM fungi in maintaining multiple soil functions by mitigating the negative impact of drought. Our study highlights the importance of AM fungi as a nature-based solution to sustaining multiple soil functions in a world where drought events are intensifying.

Listening to animal behavior to understand changing ecosystems.

Interpreting sound gives powerful insight into the health of ecosystems. Beyond detecting the presence of wildlife, bioacoustic signals can reveal their behavior. However, behavioral bioacoustic information is underused because identifying the function and context of animals' sounds remains challenging. A growing acoustic toolbox is allowing researchers to begin decoding bioacoustic signals by linking individual and population-level sensing. Yet, studies integrating acoustic tools for behavioral insight across levels of biological organization remain scarce. We aim to catalyze the emerging field of behavioral bioacoustics by synthesizing recent successes and rising analytical, logistical, and ethical challenges. Because behavior typically represents animals' first response to environmental change, we posit that behavioral bioacoustics will provide theoretical and applied insights into animals' adaptations to global change.

Sustainable bioenergy contributes to cost-effective climate change mitigation in China.

Bioenergy development is critical for achieving carbon neutrality. Biomass residues from agriculture, forest, and livestock manure provide substantial bioenergy resources in China, but their availability, climate, and economic impacts have not been evaluated systematically. Here we assess biomass sustainability, bioenergy potential, greenhouse gas emissions (GHG) reduction, and cost-effectiveness using an integrated data-modeling approach. Nationally, only 27% of biomass can be used for sustainable bioenergy production, but can contribute to significant climate change mitigation with optimized regional utilization. The annual GHG reduction can reach 1.0 Gt CO2e for bioenergy, or 1.4 Gt CO2e for bioenergy with carbon capture and storage (BECCS), which is comparable to total terrestrial ecosystem carbon sinks in China. The abatement cost varies regionally but is lower than many other carbon removal technologies. Our findings reveal region-specific bioenergy pathways that contribute to carbon neutrality, and encourage future assessments to explore factors including technological advances and carbon markets.

Path analysis for controlling climate change in global aviation.

The aviation industry's emissions have had a significant impact on global climate change. This study focuses on carbon emission trading schemes, sustainable aviation fuels (SAFs), and hydrogen energy, as vital means for the aviation industry to reduce emissions. To evaluate the climate effects of global routes under four scenarios (24 sub-scenarios) until 2100, this study proposes the Aviation-FAIR (Aviation-Finite Amplitude Impulse Response) method. The findings reveal that while CO2 emissions and concentrations are significant, other emissions, such as N2O and CH4, have a greater effective radiative forcing (ERF) and contribute significantly to climate change. Moreover, SAFs are more effective in mitigating airline pollutant emissions than relying solely on carbon trading schemes. The effectiveness of hydrogen fuel cells may be hindered by technical limitations compared to hydrogen turbine engines. The findings of this study provide reference for the global aviation industry to adopt emission reduction measures.

Land-cover change in Cuba and implications for the area of distribution of a specialist's host-plant.

Changes in land cover directly affect biodiversity. Here, we assessed land-cover change in Cuba in the past 35 years and analyzed how this change may affect the distribution of Omphalea plants and Urania boisduvalii moths. We analyzed the vegetation cover of the Cuban archipelago for 1985 and 2020. We used Google Earth Engine to classify two satellite image compositions into seven cover types: forest and shrubs, mangrove, soil without vegetation cover, wetlands, pine forest, agriculture, and water bodies. We considered four different areas for quantifications of land-cover change: (1) Cuban archipelago, (2) protected areas, (3) areas of potential distribution of Omphalea, and (4) areas of potential distribution of the plant within the protected areas. We found that "forest and shrubs", which is cover type in which Omphalea populations have been reported, has increased significantly in Cuba in the past 35 years, and that most of the gained forest and shrub areas were agricultural land in the past. This same pattern was observed in the areas of potential distribution of Omphalea; whereas almost all cover types were mostly stable inside the protected areas. The transformation of agricultural areas into forest and shrubs could represent an interesting opportunity for biodiversity conservation in Cuba. Other detailed studies about biodiversity composition in areas of forest and shrubs gain would greatly benefit our understanding of the value of such areas for conservation.

Testing the evolutionary potential of an alpine plant: Phenotypic plasticity in response to growth temperature far outweighs parental environmental effects and other genetic causes of variation.

Phenotypic plasticity and rapid evolution are fundamental processes by which organisms can maintain their function and fitness in the face of environmental changes. Here we quantified the plasticity and evolutionary potential of an alpine herb Wahlenbergia ceracea. Utilising its mixed-mating system, we generated outcrossed and self-pollinated families that were grown in either cool or warm environments, and that had parents that had also been grown in either cool or warm environments. We then analysed the contribution of environmental and genetic factors to variation in a range of phenotypic traits including phenology, leaf mass per area, photosynthetic function, thermal tolerance, and reproductive fitness. The strongest effect was that of current growth temperature, indicating strong phenotypic plasticity. All traits except thermal tolerance were plastic, whereby warm-grown plants flowered earlier, grew larger, produced more reproductive stems compared to cool-grown plants. Flowering onset and biomass were heritable and under selection, with early flowering and larger plants having higher relative fitness. There was little evidence for transgenerational plasticity, maternal effects, or genotype-by-environment interactions. Inbreeding delayed flowering and reduced reproductive fitness and biomass. Overall, we found that W. ceracea has the capacity to respond rapidly to climate warming via plasticity, and the potential for evolutionary change.

Cyanobacteria in the Anthropocene: Synanthropism forged in an era of global change.

The Anthropocene has driven a transformative era where human activities exert unprecedented influence on Earth's biosphere. Consequently, synanthropic organisms, adept at thriving in human-modified environments, have emerged. While well studied in terrestrial ecosystems, the presence and ecological importance of synanthropic species in aquatic ecosystems, specifically among cyanobacteria, are less understood. Cyanobacteria blooms, notorious for their detrimental effects on ecosystems and human health, are increasing in frequency and intensity globally. In this perspective, we explore the evidence supporting this rise of cyanobacteria blooms, emphasizing the roles of human-induced eutrophication and climate change on select cyanobacteria genera. Cyanobacteria are not a monolith, with certain genera showing an observable increase within anthropogenically modified environments. We propose the establishment of a new sub-branch of phycology that explicitly investigates the ecology and physiology of synanthropic cyanobacteria. Understanding the intricate interactions between synanthropic species and human populations is imperative for managing human-altered ecosystems and conserving freshwater resources, particularly in the face of increasing global water insecurity. PRACTITIONER POINTS: The rise in cyanobacteria blooms is driven by a small subset of human-adapted genera-synanthropic cyanobacteria. Research is needed to characterize synanthropic cyanobacteria, which will aid in developing tailored management approaches. A paradigm shift from domesticating to "rewilding" landscapes and modifying behaviors to facilitate cohabitation are solutions to reducing risks.

Limiting Resources Define the Global Pattern of Soil Microbial Carbon Use Efficiency.

Microbial carbon (C) use efficiency (CUE) delineates the proportion of organic C used by microorganisms for anabolism and ultimately influences the amount of C sequestered in soils. However, the key factors controlling CUE remain enigmatic, leading to considerable uncertainty in understanding soil C retention and predicting its responses to global change factors. Here, we investigate the global patterns of CUE estimate by stoichiometric modeling in surface soils of natural ecosystems, and examine its associations with temperature, precipitation, plant-derived C and soil nutrient availability. We found that CUE is determined by the most limiting resource among these four basic environmental resources within specific climate zones (i.e., tropical, temperate, arid, and cold zones). Higher CUE is common in arid and cold zones and corresponds to limitations in temperature, water, and plant-derived C input, while lower CUE is observed in tropical and temperate zones with widespread limitation of nutrients (e.g., nitrogen or phosphorus) in soil. The contrasting resource limitations among climate zones led to an apparent increase in CUE with increasing latitude. The resource-specific dependence of CUE implies that soils in high latitudes with arid and cold environments may retain less organic C in the future, as warming and increased precipitation can reduce CUE. In contrast, oligotrophic soils in low latitudes may increase organic C retention, as CUE could be increased with concurrent anthropogenic nutrient inputs. The findings underscore the importance of resource limitations for CUE and suggest asymmetric responses of organic C retention in soils across latitudes to global change factors.

Human-modified habitats imperil ornamented dragonflies less than their non-ornamented counterparts at local, regional, and continental scales.

Biologists have long wondered how sexual ornamentation influences a species' risk of extinction. Because the evolution of condition-dependent ornamentation can reduce intersexual conflict and accelerate the fixation of advantageous alleles, some theory predicts that ornamented taxa can be buffered against extinction in novel and/or stressful environments. Nevertheless, evidence from the wild remains limited. Here, we show that ornamented dragonflies are less vulnerable to extinction across multiple spatial scales. Population-occupancy models across the Western United States reveal that ornamented species have become more common relative to non-ornamented species over >100 years. Phylogenetic analyses indicate that ornamented species exhibit lower continent-wide extinction risk than non-ornamented species. Finally, spatial analyses of local dragonfly assemblages suggest that ornamented species possess advantages over non-ornamented taxa at living in habitats that have been converted to farms and cities. Together, these findings suggest that ornamented taxa are buffered against contemporary extinction at local, regional, and continental scales.

Stability in change: building a stable ecological security pattern in Northeast China under climate and land use changes.

Climate change and land use change caused by human activities have a profound impact on ecological security. Simulating the spatio-temporal changes in ecosystem service value and ecological security patterns under different carbon emission scenarios in the future is of great significance for formulating sustainable development policies. This study quantified the four major ecosystem services (habitat quality, water retention, soil erosion, and carbon storage) in Northeast China (NC), identified ecological source areas, and constructed a stable ecological security pattern. The results show that the spatial patterns of soil erosion, carbon storage, water retention, and habitat quality, the four major ecosystem services in NC, are relatively stable in the next 30 years, and there is no significant difference from the current spatial pattern distribution. The SSP1-2.6 carbon emission scenario is a priority model for the development of NC in the next 30 years. In this carbon emission scenario, the NC has the largest ecological resources (191,177 km2) and the least comprehensive resistance value (850.006 × 10-4). At the same time, the relative resistance of the corridor in this scenario is the smallest, and the area of the mandatory reserve pinch points is the least. The ecological corridors in the SSP1-2.6 scenario form a network distribution among the ecological sources, connecting several large ecological sources as a whole. This study fills the knowledge gap in building a stable ecological security pattern in NC under the background of global change, and provides a scientific basis for the decision-making of regional ecological security and land resource management.