Shifts in insect and pathogen pressure with climate change present a potential threat to forest health, carbon sequestration and biodiversity. Here we evaluate climatic effects on insect and pathogen incidence across North America and forecast their future trends under climate scenarios. Using Bayesian hierarchical regression fit to records on more than 1 million trees, we show that warming and drought jointly exacerbate insect and disease incidence in historically colder and wetter regions, while reducing incidence in warmer and drier regions. Models allowing contemporary climate effects to depend on historical climate context better predict observed insect and disease incidence than models assuming quadratic functions of contemporary climate alone. Climate effects on incidence further vary among host species, mediated by tree climatic niches and functional traits, and differ across insect and pathogen taxa. Using ensemble climate projections, we forecast that under the Shared Socioeconomic Pathway 2-4.5 scenario, insect and pathogen incidence will increase across, respectively, 58% and 52% of forest land over the coming decades, with the largest impacts at high latitudes. Incorporating the variability of climate impacts across space and taxa, our work will help in predicting climate-driven insect and pathogen risk for North American forests.
Road development is a major driver of forest degradation worldwide, accelerating habitat fragmentation, biodiversity loss and carbon emissions. Although these consequences have been documented in tropical forests, the spatiotemporal dynamics and ecological impacts of road expansion in boreal intact forest landscapes (IFLs) remain poorly understood, particularly for the central-eastern Siberian IFLs, an ~1.71 million km2 wilderness and carbon sink. To address this gap, we analysed 20,480 Landsat satellite images from 2000 to 2023, and found a 1.6-fold increase in road area and length across this region. Road expansion, spatially linked to logging and mining activities, occupied ~1,046 km2 of IFLs, intensified forest fragmentation 4.3-fold and increased IFL edges within 30 m of roads 1.2-fold. Between 2010 and 2023 alone, road expansion directly contributed to 39.1 megatonnes of aboveground biomass loss. These findings highlight the urgent need for improved road planning and policies that balance economic development with boreal forest conservation.
Tree diversity declines and shifts in mycorrhizal dominance may have cascading effects on multitrophic diversity. Whether the effects are additive or synergistic and consistent across taxa and functional groups is unclear. Here we test how microorganisms and invertebrates spanning multiple trophic levels, both above- and belowground, respond to experimental manipulation of tree species richness and mycorrhizal type in a young forest stand (the MyDiv experiment in Germany). Tree diversity increased belowground abundance and taxonomic richness of microorganisms and lower-trophic-level nematodes, cascading to meso- and macrofauna predators, whereas aboveground effects were limited to foliar fungi and soil-surface omnivores. Mycorrhizal type strongly structured belowground food webs and influenced aboveground predators, but mixtures showed only additive effects. For most trophic groups, diversity responses were similar across mycorrhizal types. Tree diversity and mycorrhizal type effects were mediated by leaf quality, canopy complexity and nutrient availability. Our results highlight tree diversity and mycorrhizal type as potentially distinct drivers of multitrophic biodiversity, primarily governing belowground bottom-up effects.
Emerging evidence shows that responses to deforestation can differ both across species and among populations of the same species. The reasons underlying these complex patterns are unclear, and this lack of clarity is a barrier to accurate monitoring and prediction of biodiversity change. Using data from 2,262 bird species across 7,326 sites from all forested continents, we show that between-species and within-species variations in responses to forest cover are mediated by temperature. Populations in warmer macroclimates tend to decline in incidence in deforested landscapes because hotter microclimates push them closer to their species' realized upper thermal tolerance limits. By contrast, populations in cooler macroclimates tend to be less affected by or even benefit from deforestation, as microclimatic temperatures are pushed closer to more optimal temperatures. Our findings offer an empirically grounded framework for biodiversity models that move beyond fixed species responses and incorporate interactions between temperature and land-use change.
Natural regeneration is a cost-effective alternative to tree planting for restoring degraded and converted tropical forests, contributing to climate mitigation and biodiversity recovery. However, global variation in its costs and benefits remains poorly quantified, limiting the ability of restoration programmes to strategically leverage its full potential. Here we assess this variation by integrating data on costs and ecological benefits across the tropics, spanning 7.49 million km2 of land with biophysical potential for natural forest regeneration. If completely regenerated, this additional forested area could accumulate approximately 9.57 Gt C over 30 years and reduce the overall extinction risk of forest-dependent species by about 31% relative to a baseline. We show that Indonesia, Madagascar, Philippines, México and Malaysia have the largest areas with high carbon and biodiversity benefits at low costs, which we refer to as 'holistic hotspots' for natural regeneration. We find that cost-effective areas with high carbon or high biodiversity benefits alone show different spatial patterns from holistic hotspots. These tradeoffs in achieving both benefits reduce the area of holistic hotspots to 9.67% of the entire study region. The cost-benefit maps we provide can enable decision-makers to improve their spatial planning and investment to achieve their forest restoration goals.
Building a high-integrity biodiversity credit market requires recognition of Indigenous Peoples and Local Communities as stewards of nature. Including culturally salient species as a metric in the measurement and monitoring of biodiversity credits — with the consent and guidance of Indigenous and local authorities — may be one pathway towards this pursuit.
The functions of ecosystems emerge from dynamic environments characterized by spatiotemporal heterogeneity, especially in the distribution of nutrients and organisms. This heterogeneity results in the emergence of biological hotspots, localized regions with disproportionate contributions to ecosystem functioning and biodiversity globally. While traditional hotspot approaches (for example, biodiversity hotspots) rely on static boundaries of high species endemism, trophic hotspots are highly dynamic, emerging from the localized concentration, mobilization and propagation of energy or limiting nutrients across landscapes through the foraging movements of diverse consumer taxa. Here we synthesize theory across community, foraging and food web ecologies to present trophic hotspots as a useful entry point towards studying and understanding cross-scale processes in ecology. We contend that the mechanisms that generate trophic hotspots, from marine upwellings and mineral licks to mass animal migrations, result from the same fundamental processes across ecosystems. Importantly, these hotspots reflect a critical form of spatiotemporal heterogeneity that contributes to the maintenance of function in the face of perturbations (that is, resilience). Finally, we argue that trophic hotspots represent valuable focal points for the proactive conservation and management of ecological systems in a rapidly changing world.
Predicting which non-native plant species will become established and where is critical for conserving and managing biodiversity. Theory suggests that the mycorrhizal strategy of non-native plants may predict their establishment success. Here we combine a global dataset of 440,788 vegetation plots with data on plant native status and mycorrhizal type to assess mycorrhizal strategy of non-native plants. The mycorrhizal strategy of non-native plants varies strongly across biomes. Across grassland and desert biomes, non-native species are more frequently non-mycorrhizal than native species, whereas in other biomes non-native species are more likely to be mycorrhizal, most commonly arbuscular-mycorrhizal. Disturbance type and intensity are key predictors of mycorrhizal strategy of non-native species, as mycorrhizal species are favoured by landscape modification and non-mycorrhizal species by natural and human-caused disturbance events. Facultatively mycorrhizal species are consistently under-represented among non-native plants compared with natives, suggesting that symbiotic flexibility does not confer an advantage for non-natives as previously expected. Our study shows that non-native mycorrhizal strategy varies across biogeographical contexts and disturbance, highlighting the need for region-specific prevention and management approaches to plant species introductions.
Recent changes in alpine vegetation are often attributed to climate warming, particularly community composition shifts towards more warmth-associated species, or thermophilization. Here we assess the link between thermophilization and warming across 53 European mountain summits. We combine long-term macroclimatic and microclimatic temperature time series with vegetation surveys in 724 permanent plots, monitored over 21 years, to evaluate a possible thermophilization signal and relate it to rates of change in 10 temperature metrics. We find evidence of both thermophilization of alpine plant communities and an increase in temperatures. However, although these two trends are related when averaged across mountain regions, their relationship is weak at the individual plot scale, especially when considering microclimatic temperature metrics. Instead, substrate conditions and particularly the availability of thermophilic colonizers in the surrounding vegetation have a major influence on plot-level thermophilization rates. We conclude that the response of plant communities to climate change strongly depends on the abiotic and biotic context, and intensified monitoring efforts are needed to reduce the resulting uncertainties.
Centromeric and pericentromeric regions of most eukaryotic genomes are highly repetitive and strongly recombination-suppressed, confounding efforts to resolve genetic variation, population structure and phenotypic associations. Pepper (Capsicum annuum) centromeres are nearly devoid of satellite repeats, facilitating assembly and population-level comparison of centromeric regions. Here we integrate 9 near-complete genome assemblies, CENH3 ChIP-seq profiles from 26 diverse accessions, and resequencing and phenotypic data from ~400 cultivated and wild accessions to investigate population-level diversity and phenotypic relevance of pepper peri/centromeric regions. Functional centromere positions are largely fixed on 8 of 12 chromosomes, whereas the remaining 4 carry distinct centromeric epialleles shaped mainly by centromere repositioning and pericentromeric inversions. Pepper centromeres are embedded within ultra-long centromere-spanning haplotype (cenhap) blocks, ranging from 29.8 to 112.9 Mb and collectively covering 23.96% of the genome; each block contains only 1-4 major haplotypes. Some cenhaps may act as supergene-like units and are strongly associated with fruit traits, probably because recombination-suppressed intervals harbour multiple fruit-related genes, including OFP and F-box genes. F2 segregation assays further reveal transmission distortion of chromosomes carrying alternative cenhaps. Together, these findings highlight peri/centromeric regions as underrecognized reservoirs of agronomically important variation.
A wide range of microorganisms produce storage biopolymer polyhydroxyalkanoates (sPHAs) as carbon and energy reserves. However, only bacteria and fungi are known to degrade microbial sPHAs, using enzymes called polyhydroxyalkanoate depolymerases (PHADs). Here we show that some animals also have PHADs that can degrade sPHAs. We discovered a PHAD in the gutless oligochaete Olavius algarvensis, a marine worm that gains nutrition by digesting bacterial symbionts, including a dominant symbiont in which sPHAs account for up to 42% of cellular carbon stores. Enzyme assays, combined with mass spectrometry, confirmed that heterologously expressed O. algarvensis PHAD degraded sPHAs into hydroxyalkanoate monomers that can enter conserved metabolic pathways. Imaging of mRNA showed that PHAD was expressed in the oligochaete epidermis, the site of symbiont digestion. We further identified PHADs in more than 66 gut-bearing animal species from nine phyla and 19 protist species from three major supergroups, suggesting that the last common ancestor of metazoans possessed PHADs. Functional assays confirmed that PHADs from phylogenetically distant animal lineages spanning aquatic and terrestrial environments degrade sPHAs. These findings reveal a previously unrecognized pathway by which protists and animals can access microbial carbon reserves, with broad relevance given the widespread occurrence of sPHAs across ecosystems.
Global changes are leading to widespread species redistribution. Comprehensive assessments of range shift dynamics and their drivers are difficult, partly due to the variation in range shift detection over space and taxa. Here we compile documented range shift records for 1,758 butterfly species from 105 countries and territories, representing ~10% of the known diversity of these insects. Most species (80%) experienced range expansions, and most range shifts (79%) were associated with climate change and extreme weather events. A substantial proportion of species in our dataset contracted their ranges (27%) or shifted along elevational gradients (22%). We report widespread horizontal range expansions and contractions across tropical countries, with less evidence for elevational range shifts. We show that a clearer picture of range shift dynamics emerged only through the combination of different types of data, with expert assessments and non-English studies alleviating potential biases. Our findings of climate-driven range shifts call for concerted efforts to improve inclusive data monitoring and conservation efforts, especially for tropical countries, where human-induced land-use changes exert additional critical pressure.
In response to increasing human pressures on biodiversity, conservation targets have been set to reduce these pressures and halt biodiversity decline. However, consequences of these objectives on common species are rarely studied. We analyse the effect of a range of drivers related to climate, land use and land-use intensity on 265 common bird and 144 common butterfly species from more than 20,000 sites between 2000 and 2021 across 27 European countries. We use land use and land-use intensity scenarios produced previously using the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) Nature Futures Framework and climate change scenarios to project biodiversity drivers in Europe up to 2050. We translate these driver changes into abundance variations for common bird and butterfly species and for multi-species indicators used to monitor common biodiversity status in Europe. The projected trends relatively improve, while still declining for birds, notably farmland species, under the scenarios meeting conservation objectives, with few effects on butterflies. No scenario shows a stop or a reversal in the average decline in abundance of bird and butterfly species. Our results therefore question the common biodiversity future under current conservation policies and highlight the need for other anticipatory frameworks not implicitly based on a growing need for natural resources.
Mature forests are often assumed to approach carbon saturation, yet their role in continued carbon accumulation remains uncertain. Here we show that, across the conterminous USA, carbon accumulation in mature forests, covering ~72% of forest area, is systematically underrepresented by current satellite-derived biomass estimates relative to lidar, forest inventories and ecosystem models. Satellite estimates indicate near-neutral biomass changes over recent decades, whereas forest inventories estimate an increase of 102 TgC yr-1. Repeat lidar and forest inventory measurements reveal widespread structural and carbon growth, including in tall forests. By contrast, satellite estimates fail to capture growth beyond canopy closure, showing little biomass increase once canopy height exceeds ~16 m. This asymmetric bias preferentially detects losses over gains yielding a weaker inferred land carbon sink. These findings reveal a critical observational gap in carbon dynamics in mature forests, suggesting that the land carbon sink may be systematically underestimated and highlighting the need for Earth observations sensitive to forest structure and their integration with forest inventories and ecosystem models.
