ABSTRACT Aim We tested how climate–growth relationships, temporal coherence and responses to compound climate extremes vary across a regional elevational gradient occupied by Pinus flexilis . Location Greater Yellowstone Ecoregion, northwestern Wyoming, USA. Time Period Dated tree‐ring material spans 514–2020 ce , with detailed analyses focused on the past millennium. Major Taxa Studied Limber pine ( Pinus flexilis James). Methods We developed three millennial‐length ring‐width chronologies from high‐, mid‐ and low‐elevation sites. We compared radial growth with instrumental and reconstructed climate, quantified shared and elevation‐dependent growth patterns using PCA and moving‐window analyses, and evaluated growth responses to compound hot‐dry and cool‐wet extremes. Results Growth at all elevations was moisture sensitive and declined during warm summer conditions, indicating that heat amplified water limitation across the gradient. The chronologies shared a broad hydroclimatic signal, but the high‐ and low‐elevation sites often differed in growth magnitude and in the timing of growth responses. High‐elevation Wolf Knob temporarily decoupled from the dominant growth pattern during cool Little Ice Age conditions, whereas low‐elevation Outlaw Ridge showed the most persistent growth suppression following hot‐dry extremes. Main Conclusions Across the sampled ecological amplitude in the GYE, P. flexilis growth reflects both shared hydroclimatic variability and elevation‐specific constraints. Future warming may reduce cold limitation near upper treeline in some years, but is likely to intensify moisture limitation and drought legacy effects at lower elevations.
ABSTRACT Aim Newly documented records are widely used as historical evidence for species redistribution, especially where continuous monitoring is unavailable. However, they are often summarized as range expansion or directional shifts, without testing whether they deviate from random additions to incomplete biodiversity baselines. Here, we ask whether newly documented bird records reveal structured distributional knowledge accumulation, shaped by prior distributions, species traits and habitat context. Location China. Taxon Birds. Methods We compiled seven national bird checklists spanning 1955 to 2023 and analysed 2258 newly documented subregional records. Using nullmodel‐based metrics, we compared the proximity and northward displacement of new records with random expectations. We then related these spatial patterns to species traits and tested whether new records occurred in land‐cover contexts matching species' primary habitat preferences. Results New records accumulated unevenly across taxa, time and zoogeographical regions. They occurred significantly closer to prior distributions than expected, and this proximity was stronger in species with restricted distributions and narrower habitat breadths. Migratory species were distributed farther north than expected under the null model during most of the study period, especially among species with broader distributions and greater ecological flexibility. While resident species were generally distributed farther south than expected. Habitat analyses further showed that new records were more often located in land‐cover contexts matching species' primary habitats, both in current landcover composition and temporal land‐cover change. Main Conclusions Long‐term changes in documented bird distributions in China cannot be reduced to simple range expansion or poleward displacement. Repeated national checklists reveal spatial, trait and habitat patterns in new records, highlighting a structured process of distributional knowledge accumulation in an incomplete biodiversity baseline. Our framework helps distinguish random additions to incomplete biodiversity baselines from structured distributional knowledge accumulation, especially where continuous standardised monitoring is limited.
ABSTRACT Aim Extreme climatic events (ECEs) are increasingly recognized as major drivers of insect declines, yet remain rarely incorporated into biodiversity projections. Butterflies may be especially sensitive to prolonged ECEs because they are short‐lived ectotherms, while voltinism can influence their capacity to absorb climatic shocks. We assessed how the frequency of prolonged ECEs may reshape butterfly climatic suitability and richness patterns across Italy and whether responses vary among biomes and voltinism classes. Location Italy. Time Period Baseline (1971–2000) and mid‐century (2041–2070). Major Taxa Studied Diurnal butterflies (Papilionoidea). Methods We derived spatially explicit indices of hot, cold, dry and wet spells from EURO‐CORDEX climate projections and used them to build ensemble species distribution models for 199 butterfly species. We mitigated sampling bias with a target‐group pseudo‐absence approach and defined ecologically meaningful calibration areas based on occupied biomes. We projected changes in climatic suitability and richness under Representative Concentration Pathway (RCP) 2.6, a mitigation scenario, and RCP8.5, a high‐emission scenario, and compared responses among biomes and voltinism classes. Results Projected suitability changes were predominantly negative across all biomes and consistently stronger under RCP8.5 than under RCP2.6. Univoltine species were most negatively affected, whereas bivoltine and multivoltine species showed broader and more heterogeneous responses. Mediterranean and Temperate Broadleaf assemblages showed marked suitability declines and widespread richness losses under RCP8.5. Temperate Conifer assemblages showed smaller percentage suitability declines but greater richness losses, suggesting that even moderate suitability reductions may translate into strong impacts in montane ecosystems. These patterns also reflected biome‐specific changes in ECE frequencies, although scenarios generally indicated more frequent hot spells and fewer cold spells across biomes. Main Conclusions Future ECEs may substantially reshuffle butterfly assemblages across Italy, with impacts varying among biomes and voltinism classes. Explicitly integrating spell‐based ECE indices into biodiversity projections may improve assessments of climate‐change impacts on insects and inform proactive conservation planning.
ABSTRACT Aim Groundwater ecosystems host a highly diverse and specialized biodiversity; however, current knowledge remains limited, partly due to the low accessibility of subterranean environments. We aimed to delineate Areas of Endemism (AoEs) for European groundwater copepods, concurrently developing a reproducible, conservation‐oriented workflow to individuate areas of high endemicity under sparse data availability. Location Europe. Taxon Crustacea: Copepoda. Methods We took advantage of the EGCop dataset, retaining 5709 occurrences across 467 obligate groundwater‐dwelling species after data filtering for taxonomic uncertainty. AoEs were delineated using a grid‐free, density‐based clustering approach (CLUENDA, DBSCAN‐based) across 60 parameter combinations. A consensus procedure was applied to identify robust AoEs, namely those emerging from ≥ 95% of parameter combinations. We also developed a species‐level Endemicity Score (ES) as a function of spatial dispersion of occurrence records. Based on ES, we derived three AoE‐level metrics, respectively representing raw, richness‐weighted and density‐weighted endemicity. Results We identified 17 robust AoEs across Europe (i.e., areas consistently supported across different parameter combinations), largely associated with karst regions and historically stable hydrogeological systems. These AoEs varied widely in extent, species richness and endemicity. A total of 91 point endemics (i.e., species known only from a single locality) were recorded within the identified AoEs. Endemicity patterns differed among metrics, with some areas maximizing total endemicity and others showing higher richness‐weighted or density‐weighted scores. Nonetheless, narrow‐ and point‐endemic taxa consistently shaped the observed spatial patterns of endemicity. Main Conclusions European groundwater ecosystems are structured into distinct centres of endemism driven by hydrogeological compartmentalization, long‐term isolation and limited dispersal. The high frequency of point endemics implies that local habitat loss may cause irreversible loss of unique lineages. By integrating grid‐free clustering, endemicity weighting and sensitivity analysis, our framework provides a reproducible and conservation‐relevant tool for identifying priority areas under uncertainty, with potential applications across other sparsely sampled subterranean taxa.
ABSTRACT Aim Climate change and anthropogenic disturbances are driving biodiversity loss across multiple functional groups and spatial scales, potentially weakening the ability of ecosystems to sustain multiple functions simultaneously. However, it remains unclear how diversity across functional groups regulates ecosystem multifunctionality (EMF) across spatial scales, particularly in mountain forests with strong climatic gradients. Location Southeastern China. Taxon Woody plants. Methods Here, we assembled data on seven functional groups, including trees, shrubs, herbs, bacteria, pathogenic fungi, saprotrophic fungi and symbiotic fungi, and 10 ecosystem functions representing supporting, provisioning and regulating services. Within the Hill–Chao numbers framework, we quantified the diversity of each functional group and partitioned EMF at the larger spatial scale (γ‐EMF) into its α and β components. We then synthesized the diversity measures of all functional groups (except trees) into a single composite diversity measure across functional groups. We used a multiscale perspective to evaluate how tree diversity regulates EMF through multidiversity across functional groups at different spatial scales. Results We found that α‐ and β‐diversity increased γ‐EMF through their positive effects on α‐EMF and β‐EMF, respectively. Specifically, tree diversity can promote EMF across spatial scales both directly and indirectly by enhancing diversity across multiple functional groups. The α‐ and β‐diversity across multiple functional groups had stronger positive effects on α‐ and β‐EMF, respectively, than diversity within any single functional group. Additionally, elevation influenced EMF across spatial scale by reducing diversity across functional groups at multiple spatial scales. Main Conclusions Our results highlight that maintaining higher diversity across multiple functional groups is critical for sustaining EMF at both local and broader spatial scales in mountain forests. By integrating diversity across multiple functional groups and spatial scales, our study advances understanding of the patterns and mechanisms linking biodiversity and EMF in mountain forest ecosystems and highlights the necessity of a holistic conservation strategy that explicitly considers multiple functional groups.
