Limited Range Research Articles

Environmental variability across space and time drives the recolonization pattern of a historically persecuted large carnivore

Wildlife populations are not static. Intrinsic and extrinsic factors affect individuals, which lead to spatiotemporal variation in population density and range. Yet, dynamics in density and their drivers are rarely documented, due in part to the inherent difficulty of studying long-term population-level phenomena at ecologically meaningful scales. We studied the spatiotemporal density dynamics in a recolonizing large carnivore population, the wolverine Gulo gulo, across the Scandinavian Peninsula over nine years. We fitted open-population spatial capture-recapture models to noninvasive genetic sampling data collected across Norway and Sweden to estimate annual density surfaces and their drivers. This approach allowed us to model sex-specific changes in wolverine density and the effect of landscape-level environmental determinants over time. Our results revealed that, as wolverines successfully recolonized many parts of their historical range in Scandinavia, the relationship with spatial determinants of density has changed over time. We also found support for sex-specific responses of the Scandinavian wolverine to the environmental determinants of density and differences in the temporal dynamics of their relationships, indicating disproportionate recolonization ability and anthropogenic pressures. We observed significant changes in the relationship of female wolverine density with several determinants during the study period, suggesting still ongoing expansion of female wolverines whereas males might have already reached the range limits. These findings show that the Scandinavian wolverine population is still recovering from centuries of persecution and severe range contraction. Our study sheds light on the dynamics and challenges of recolonizing large carnivores in human-dominated landscapes across time and space.

Multi-decade northward shift of loggerhead sea turtle pelagic habitat as the eastern North Pacific Transition Zone becomes more oligotrophic

The North Pacific Transition Zone (NPTZ) is known as a global marine hotspot for many endangered and commercially significant highly mobile marine species. In the last few decades, the region has undergone unprecedented physical and biological transformations in response to climate variability and change. Although it is anticipated that many highly mobile species will need to adapt and shift their distributions, current predictions have relied on short-term data sets or modeled simulations. This has left a critical gap in our understanding of long-term (decadal or longer) change and species’ responses within the NPTZ. Here, we integrate nearly 3 decades of satellite tracking data from a climate sentinel, the juvenile North Pacific loggerhead sea turtle (Caretta caretta), with concurrent observations of sea surface temperature (SST) and chlorophyll-a concentrations to examine higher trophic level response to climate-induced changes within the eastern bounds of the NPTZ. Between 1997–2024, the NPTZ has warmed by 1.6°C and experienced an approximately 19% decline in mean surface chlorophyll-a concentration, a proxy for reduced productivity, resulting in a 28% (1.65 million km2) increase in total oligotrophic habitat in the eastern NPTZ. Over the same period, the average latitude of loggerhead sea turtle foraging habitat in the NPTZ has shifted northwards by 450–600 km. This represents a distributional shift rate of 116–200km/decade. In most years both the southern and northern range limits for the loggerhead turtle have shifted northward in tandem, indicating a habitat range shift rather than a range expansion. Our findings reveal significant physical and biological change to the NPTZ over the last quarter century and the first empirical evidence illustrating the substantial spatial response of a highly mobile megafaunal species. As the NPTZ continues to become more oligotrophic, these insights can provide vital information for dynamic conservation and management strategies within this critically important ecosystem.

Advanced IoT-integrated parking systems with automated license plate recognition and payment management

Urban parking management is a growing challenge with increasing vehicle numbers and limited parking space. Traditional methods often fail during peak hours, leading to inefficiencies, unauthorized usage, and revenue losses. For instance, a parking lot designed for 300 vehicles often exceeds 90% occupancy during peak times, creating congestion and billing inaccuracies. This research proposes an automated system integrating sensors, image processing, and database management to address these issues. A single camera monitors multiple parking slots, with predefined coordinates linked to IR sensors for dual verification. Image processing algorithms, including Optical Character Recognition (OCR), enable accurate license plate recognition. Testing under real-world conditions showed 95% accuracy in daylight, 90% in low light, and 93% for plates at 45-degree angles. Detection accuracy reached 88% at distances of 1.5–3 m, ensuring reliable operation even at the camera’s range limits. Occupancy tracking achieved less than a 5% error margin compared to manual methods, while the fare calculation module reduced billing errors by 90%, enhancing efficiency and revenue. The system’s scalable design supports applications in parking management, toll collection, and traffic monitoring. By improving vehicle detection, occupancy tracking, and billing accuracy, this solution addresses critical challenges in urban parking and contributes to smarter city infrastructure.

Dispersive Solid Phase Extraction Using Folic Acid Coupled with a Modified Glassy Carbon Electrode for Electrochemical Sensing of Favipiravir in Urine and Water Samples

An acid-base reaction-based dispersive solid-phase extraction approach was developed for extracting favipiravir before its determination using an electrochemical sensor. The analyte was extracted from the samples using folic acid as an adsorbent. Cu@MoO2 nanoparticles were synthesized by chemically reducing CuMoO4 with NaBH4 and nitrogen-rich carbon (N-C) was prepared from safranine-O dyes. The characterized Cu@MoO2/N-C composites were used as an electrode modifier. The linear range and detection limit of the favipiravir were found to be 0.01-10 µM and 0.7 nM, respectively. The developed system was applied to determine favipiravir in urine and water samples, with recoveries of 101-102% and 97-99%, respectively.

Assessment of greenness, blueness, and whiteness profiles of a validated HPLC-DAD method for quantitation of Donepezil HCl and Curcumin in their laboratory prepared co-formulated nanoliposomes

White and Green Analytical Chemistry are innovative approaches in analytical chemistry that prioritize both sustainability and efficiency. Together, these approaches aim to advance scientific research while minimizing environmental impact and enhancing safety. This integration of environmental consciousness into analytical practices represents a significant step forward in achieving sustainable scientific progress. In the present study, a sensitive eco-friendly HPLC-DAD method was carried out and validated to allow concurrent determination of Donepezil HCl (DPZ) and Curcumin (CUR) in their pure form and laboratory made nano-liposome formulation. Optimum seperation was accomplished by utilising Zobrax Eclipse Plus C18 column (4.6*100 mm,5 μm) with gradient elution of the mobile phase composed of 0.02 M phosphate buffer at pH 3.2 and ethanol at flow rate of 1.5 ml/min. A diode array detector (DAD) was implemented for detection at 273 nm and 435 nm for DPZ and CUR, respectively, with the column oven set at 40 °C. The method was validated according to ICH specifications in terms of accuracy, precision, linearity range, detection and quantification limit. The calibration plots were linear with correlation coefficients (r2) = 0.999 over the range (0.1–100 µg/ml) and (0.1–100 µg/ml) for DPZ and CUR, successively. The validated HPLC-DAD approach was adopted to analyse both medications in laboratory prepared nano-liposomal formulation in which the analytes were successfully quantified with good recovery values and no disrubtion from the added excipients. The investigation of whiteness, blueness, and greenness metrics revealed a major benefit of the suggested approach over previous reported ones.

American beech mortality in stands recently infected by beech bark disease: implications for partial cutting

Beech bark disease is a major concern for northern hardwood forest management that affects most of the American beech range in North America. In infected stands, mitigating effects of the disease and promoting more resistant beech populations for natural regeneration relies heavily on our ability to identify high-risk trees and adapt tree marking for partial harvesting. We monitored several individual characteristics, including external signs of disease, on 871 beech trees in recently infected northern hardwood stands at the northern range limit of American beech in Canada, to assess their ability to predict mortality over an eight-year period. At the stand level, the mortality rate over the study period was 29.3%, while the uninfected rate was 16.6%. At the tree level, the diameter, the levels of Neonectria perithecia coverage on the stem, crown dieback, and the level of canker coverage on the bark had the greatest capacity to predict individual short-term mortality. Therefore, tree markers should first select trees with a diameter > 20 cm that are affected by any sign or symptom of the disease, followed by smaller trees with > 10% coverage of Neonectria perithecia or crown dieback > 25%, and lastly, trees with > 50% coverage of canker.

Study on automated guided vehicle collision avoidance mechanism with external computer vision

In industrial automation, safely operating Automated Guided Vehicles (AGVs) in dynamic environments is challenging. Traditional collision avoidance methods, which rely on technologies like LiDAR (Light Detection and Ranging), have limitations in detection range, accuracy, and cost. This study introduces a new method called the Collision Avoidance System with External Computer Vision (CAECV). CAECV uses two cameras which are equipped on the wall in the factory to detect obstacles, and AGV don’t need to equip any obstacle detection sensors. The detection algorithm, combining YOLOv8 with an attention mechanism, excels at identifying obstacles. The system then converts image coordinates to global coordinates using inverse perspective mapping for precise obstacle localization. Experimental comparisons with traditional TIM laser scanning radar show that CAECV outperforms in detection range, response time, accuracy, and cost. CAECV offers a broader detection range, quicker response, and lower error rates. As more AGVs are deployed, CAECV becomes significantly more cost-effective than LiDAR-based systems. Moreover, CAECV can be integrated with LiDAR systems to enhance AGV obstacle avoidance. CAECV represents a scalable, accurate, and economical advancement in AGV collision avoidance technology for modern industrial use.

Micro-ring wavelength selective switch device based on contra-DC

This paper presents, to our knowledge, a novel micro-ring wavelength selective switch device based on a contra-directional coupler (contra-DC), which utilizes the transparent window formed by the contra-DC to select the single resonant wavelength of the micro-ring resonator, avoiding the limitation of free spectral range and realizing the function of wavelength selection/switching. The desired wavelength switching function is achieved by changing the crystal state of the Ge2Sb2Te5 (GST) loaded on the micro-ring resonator. When the device is in the on state, the desired wavelength signal is selectively output from the drop port of the bus waveguide; when the device is in the off state, light is output from the through port. By modifying the GST crystal state, selective routing of light can be achieved, which can be used in optical interconnection networks. The simulation is performed using a 3D finite-difference method. The wavelength selection device achieves a 3 dB bandwidthof 1.6 nm with a side lobe suppression ratio of 20 dB at a length of 230 µm; the switching device achieves the extinction ratio of about 14.7 dB and a side lobe suppression ratio of 18.2 dB between the on/off states.

Prohibited Mountains and Forests in Late Imperial China

This essay explores the various types of spaces, primarily montane forested areas, where human access was restricted, either conditionally or entirely, during late imperial times. The range of restrictions always included felling trees, but often also encompassed other forms of extraction from local ecosystems. Based on the motivations for setting up and regulating such zones, it proposes a typology that includes imperial parks and graves, sacred sites, military exclusion zones, and certain forested commons. Based on some commonalities between these types, it concludes by reflecting on the place of notions of sacrality in local policies that directly impacted forested areas.

Impacts of limits to adaptation on population and community persistence in a changing environment.

A key issue in predicting how ecosystems will respond to environmental change is understanding why populations and communities are able to live and reproduce in some parts of ecological and geographical space, but not in others. The limits to adaptation that cause ecological niches to vary in position and width across taxa and environmental contexts determine how communities and ecosystems emerge from selection on phenotypes and genomes. Ecological trade-offs mean that phenotypes can only be optimal in some environments unless these trade-offs can be reshaped through evolution. However, the amount and rate of evolution are limited by genetic architectures, developmental systems (including phenotypic plasticity) and the legacies of recent evolutionary history. Here, we summarize adaptive limits and their ecological consequences in time (evolutionary rescue) and space (species' range limits), relating theoretical predictions to empirical tests. We then highlight key avenues for future research in this area, from better connections between evolution and demography to analysing the genomic architecture of adaptation, the dynamics of plasticity and interactions between the biotic and abiotic environment. Progress on these questions will help us understand when and where evolution and phenotypic plasticity will allow species and communities to persist in the face of rapid environmental change.This article is part of the discussion meeting issue 'Bending the curve towards nature recovery: building on Georgina Mace's legacy for a biodiverse future'.

Development of a Novel Electrochemical Immunosensor for Rapid and Sensitive Detection of Sesame Allergens Ses i 4 and Ses i 5

Due to their lipophilicity and low content, the major sesame oleosin allergens, Ses i 4 and Ses i 5, are challenging to identify using conventional techniques. Then, a novel unlabeled electrochemical immunosensor was developed to detect the potential allergic activity of sesame oleosins. The voltammetric immunosensor was constructed using a composite of gold nanoparticles (AuNPs), polyethyleneimine (PEI), and multi-walled carbon nanotubes (MWCNTs), which was synthesized in a one-pot process and modified onto a glass carbon electrode to enhance the catalytic current of the oxygen reduction reaction. The oleosin antibody was then directed and immobilized onto the surface of the electrode, which had been modified with streptavidin (SPA), through the fragment crystallizable (Fc) region of the antibody. Under optimized conditions, the immunosensor exhibited a linear response within a detection range of 50 to 800 ng/L, with detection limits of 0.616 ng/L for Ses i 4 and 0.307 ng/L for Ses i 5, respectively. The immunosensor demonstrated excellent selectivity and stability, making it suitable for the quantification of sesame oleosins. The comparative analysis of various detection methods for sesame allergens was conducted, revealing that the immunosensor achieved a wide detection range and low limit of detection (LOD). Compared to traditional enzyme-linked immunosorbent assay (ELISA), the immunosensor successfully quantified the allergenicity potential of Ses i 4 and Ses i 5 in roasted sesame seeds at temperatures of 120 °C, 150 °C, and 180 °C. This innovative method offers a new perspective for the rapid quantification of sesame oleosins in foods and real-time monitoring of allergic potential, providing significant advancements in the field of food allergy detection.

Developmental plasticity does not improve performance during a species interaction: Implications for species turnover.

Species interactions can contribute to species turnover when the outcomes of the interactions are context dependent (e.g., change along environmental gradients). Plasticity may change this dynamic by altering the environmental tolerances of the species interacting. Here, we explored how the competitive interaction between two euryhaline fish, Poecilia reticulata and Poecilia picta, is influenced by acute and developmental responses to salinity. In Trinidad, P. reticulata is confined to freshwater despite being tolerant of brackish water. P. reticulata may fail to occupy brackish water because of reduced tolerance to salinity or because P. picta competitively excludes them, and developing in brackish water could alter the dynamics of either scenario. To test this, we compared the salinity tolerances of both species in the absence of competition, reared P. reticulata individuals in freshwater or brackish water, and tested the consequences of developmental plasticity in experiments in which P. reticulata competed against conspecifics or P. picta during acute exposure to freshwater or brackish water. We found that (1) P. reticulata has a weaker salinity tolerance than P. picta; (2) P. reticulata that developed in freshwater perform best when competing against P. picta in freshwater but perform poorly when competing against P. picta in brackish water, suggesting the species interaction is context dependent; and (3) developing in brackish water did not benefit P. reticulata in brackish water. Our results suggest that P. reticulata's freshwater range limit is in part a product of a lower salinity tolerance leading to a decrease in competitive performance in brackish water. Adaptive plasticity has been suggested to be a crucial part of the colonization process, yet nonadaptive plastic responses as found here can limit range expansion and reinforce range limits.

Management of Labral Tears in the Hip: A Consensus Statement.

Inconsistencies in the workup of labral tears in the hip have been shown to result in a delay in treatment and an increased cost to the medical system. To establish consensus statements among Canadian nonoperative/operative sports medicine physicians via a modified Delphi process on the diagnosis, nonoperative and operative management, and rehabilitation and return to play (RTP) of those with labral tears in the hip. A consensus statement. A total of 40 sports medicine physicians (50% orthopaedic surgeons) were selected for participation based on their level of expertise in the field. Experts were assigned to 1 of 4 balanced working groups defined by specific subtopics of interest. Consensus, strong consensus, and unanimous consensus were defined as achieving 80% to 89%, 90% to 99%, and 100% agreement with a proposed statement, respectively. There was a unanimous consensus that several prognostic factors-including age, pain severity, dysplasia, and degenerative changes-should be taken into consideration with regard to the likelihood of surgical success. There was strong agreement that the cluster of symptoms of anterior groin pain, pain in hyperflexion, and sharp catching pain with rotation make a diagnosis of a labral tear more likely, that radiographs-including a minimum of a standing anteroposterior pelvis and 45° Dunn view-should be obtained in all patients presenting with a suspected labral tear, that a diagnostic injection should be performed if there is uncertainty that the pain is intra-articular in origin, and that a minimum of 6 months should elapse after surgical treatment before reinvestigation for persistent symptoms. Overall, 76% of statements reached a unanimous/strong consensus, thus indicating a high level of agreement between nonoperative sports medicine physicians and orthopaedic surgeons on the management of labral tears in the hip. The statements that achieved unanimous consensus included the timing of RTP after surgery, prognostic factors affecting surgical success, and the timing to begin sport-specific training after nonoperative management. There was no consensus on the use of orthobiologics for nonoperative management, indications for bilateral surgery, whether the postoperative range of motion and weightbearing restrictions should be employed, and whether postoperative hip brace usage is required.

The PSO-IFAH optimization algorithm for transient electromagnetic inversion.

As a non-contact method, the transient electromagnetic (TEM) method has the characteristics of high efficiency, small impact of device, no limitation of site range, and high resolution, and is a hot topic in current research. However, the research on the refined data processing method of TEM is lag, which seriously restricts the application in superficial engineering investigation and is a key problem that needs to be solved urgently. The particle swarm optimization (PSO) algorithm and firefly algorithm (FA) were successful swarm intelligence algorithms inspired by nature. However, the accuracy and efficiency of the algorithm restrict its further development. In this paper, the particle moving velocity of FA algorithm is defined according to the concept of particle moving velocity in PSO algorithm, so as to improve the local fast convergence ability of FA algorithm. On this basis, the appropriate velocity of particle movement is improved, so that the improved algorithm can overcome the oscillation problem around the optimal solution and improve the computational efficiency. And finally, an improved PSO-IFA hybrid optimization algorithm (PSO-IFAH) was proposed in the paper. The proposed algorithm can exploit the strong points of both PSO and FA algorithm mechanisms. A typical layered model was established, and the PSO algorithm, FA algorithm, and PSO-IFAH algorithm were applied to inversion calculations. The results show that the PSO-IFAH algorithm improves calculation accuracy by more than 80% and efficiency by over 60% compared to the PSO and FA algorithms, respectively. The PSO-IFAH algorithm also exhibits high inversion accuracy and stability, with superior anti-noise properties compared to the other algorithms. When implemented in ground TEM measurement data processing, the PSO-IFAH algorithm enhances the resolution of anomalies and low-resistance details, aligning well with actual excavation results. This highlights the algorithm's capability to depict underground electrical structures and karst developments accurately, thereby improving the precision of TEM data processing and interpretation.

A chemically modified DNAzyme-based electrochemical sensor for binary and highly sensitive detection of reactive oxygen species.

Reactive oxygen species (ROS) play a critical role in regulating various physiological processes. To gain a comprehensive understanding of their distinct functions in different physiological events, it is imperative to detect binary ROS simultaneously. However, the development of the sensing method capable of binary ROS detection remains a significant challenge. In this study, we address this challenge by integrating chemically modified DNAzyme probes with a functionalized metal-organic framework (MOF) to create an efficient electrochemical sensing platform for the binary detection of ROS. ROS targets would activate the DNAzyme cleavage activity by removing the phenylboronate (BO) and phosphorothioate (PS) modifications, leading to the controlled release of doxorubicin (DOX) and methylene blue (MB) enclosed within MOF nanocomposites. This process generates two distinct voltammetric current peaks, with their potentials and intensities reflecting the identity and concentration of the ROS targets. The sensor demonstrates simultaneous detection of multiple ROS (H2O2 and HClO) produced by cancer cells with high sensitivity across a broad linear range of 1 to 200 nM and a low detection limit in the sub-nanomolar range. The design strategies behind the developed ROS sensing system could also be exploited to create other biosensors with highly sensitive and binary detection to promote clinical research and revolutionize disease diagnostics.

Hydrogen flammability and explosion concentration limits for a wide temperature range

Hydrogen flammability and explosion concentration limits for a wide temperature range

Active site-inspired multicopper laccase-like nanozymes for detection of phenolic and catecholamine compounds.

Phenolic compounds are typical organic pollutants which cause severe human health problems due to their teratogenesis, carcinogenesis, neurotoxicity, immunotoxicity and endocrine disruption. Natural laccase is a multicopper oxidase existing in bacteria, plants, and insects, which can accelerate the transformation of phenolic compounds to their less hazardous oxidized products under mild conditions without harmful byproducts. Despite eco-environmentally friendly property of laccase, it still faces constraints of widespread application attribute to its high cost, complex preparation, and vulnerability. Therefore, exploring laccase mimics with high catalytic activity attracts a lot of attention and endeavors. In this research, copper-based nanozymes were prepared with coordination of copper ions and imidazole for mimicking the active sites of natural laccase via solvothermal method. The obtained Cu-based (Cu-Im) nanozymes exhibited multiple redox valence states of Cu and laccase-mimicking coordination structures, which endow Cu-Im with high laccase-like activity. During the process of catalytic oxidation reactions, singlet oxygen and superoxide anions generated from oxygen. Encouraged by the catalytic property, Cu-Im was utilized in degradation and detection of phenolic and catecholamine compounds. The catalytic degradation of compounds by Cu-Im showed good conversion and substrate versatility, which can be used as a kind of potential materials for phenolic pollutant degradation and remediation. Simultaneously, colorimetric sensors of phenols and catecholamines based on Cu-Im in solution system and POCT pad platform were constructed which indicated wide linear range and low limit of detection for both detection strategies. The Cu-Im-based sensor was a promising method for sensitive, fast, convenient, and qualitative-quantitative colorimetric analysis of phenols and catecholamines. The outcomes of this research elucidate Cu-Im is a satisfactory substitute for natural laccase, which will have broad application prospects in laccase-related fields, such as environmental recovery, pollution monitoring, and diagnosis of neurological diseases etc.

An active-conductive layer stacked sensor platform for real-time detection of heavy metal ions

The development of electrochemical sensors with high sensitivity and accuracy is crucial for the detection of low-concentration heavy metal ions (HMIs) such as Pb(II) and Hg(II), which remains challenging. To address this issue, MgFe-layered double hydroxide (MgFe-LDH) is synthesized as an active layer on the conductive layer SnO2 loaded with nickel foam (NF) with the assistance of oxygen vacancies (OVs) to form an active-conductive layer stacked sensor. The results show that MgFe-LDH@SnO2/NF exhibits superior sensitivity (Pb(II): 417 μA/μM; Hg(II): 986 μA/μM), wider linear range (1.1–2.2 μM) and lower limits of detection (Pb(II): 1.21 nM; Hg(II): 3.7 nM). The high performance of our sensor is attributed to the improved ability to adsorb HMIs via OV reduced binding energy as well as the promoted rapid electron transport via SnO2 reduced charge transfer resistance, as evidenced by density functional theory and electrochemical measurements. Particularly, by combining the newly proposed tiny electrochemical detection network (ECDNet-tiny) and WeChat mini program, we have built a real-time detection platform for Pb(II) and Hg(II) pollution categories and concentrations, which shows high accuracy (0.98) and recovery rate (91.6 %-106.8 %) in the detection of actual water samples. The qualitative and quantitative calculations of electrochemistry is innovatively implemented by deep learning. Besides, smartphones could display detection results transmitted from cloud servers. Thus, this work provides a new sensor platform to improve the sensitivity, accuracy, and intelligence of detecting quintessential HMIs.

Electrochemical Detection and Characterization of Caffeine in Selected Tea Samples using Polyglycine Modified Carbon Paste Electrode

Glycine was electro-polymerized against a carbon paste electrode (CPE) to produce a polymer film via the electro-oxidation process comprising amino (-NH2) and carboxylic (-COOH) groups, by a cyclic voltammetric. The electrochemical oxidation of caffeine was examined in 0.2 M phosphate buffer solution (PBS). The Polyglycine modified Carbon Paste Electrode (PGMCPE) demonstrates greater electrocatalytic activity for caffeine as compared to the unmodified CPE (UNMCPE). This made it suitable for analyzing caffeine owing to its increased electrode surface area and/or improved electron transport at the electrode surface. By varying the concentration range from 0.05 to 0.9 mM, the relationship between peak current and caffeine concentration was studied and this produced a correlation coefficient of R2 = 0.9987. This method was extremely capable of evaluating caffeine concentrations. Square wave voltammetry (SWV) was utilized to assess the caffeine in tea samples. The sample was analyzed with square wave voltammetry and was made easier with an ideal pH of 12.0. Additionally, the caffeine levels in a tea sample were successfully measured using the linear range and detection limit, and the results showed a good limit of detection (LOD) in comparison to previous literature.

Local conditions have greater influence than provenance on sugar maple (Acer saccharum Marsh.) frost hardiness at its northern range limit.

In temperate and boreal ecosystems, trees undergo dormancy to avoid cold temperatures during the unfavorable season. This phase includes changes in frost hardiness, which is minimal during the growing season and reaches its maximum in winter. Quantifying frost hardiness is important to assess the frost risk and shifts of species distribution under a changing climate. We investigate the effect of local conditions and intra-specific variation on frost hardiness in sugar maple (Acer saccharum Marsh.). Seedlings belonging to seven provenances from the northern area of the species' range were planted at two sites in Quebec, Canada. LT50, i.e., the lethal temperature for 50% of the cells, was measured monthly with the Relative Electrolyte Leakage (REL) method on branches and buds from September 2021 to July 2022. LT50 varied between -4°C in summer (July) and-68°C in winter (February). Autumnal acclimation rates (September to early December) and mid-winter frost hardiness (December to early March) were similar in both sites. Samples in the southern site deacclimated faster than in the northern site between March and July, because of a warmer and earlier spring. No difference in frost hardiness was detected between provenances. Our results suggest that the frost hardiness trait is similar within the northern part of the sugar maple distribution, with local weather conditions having a greater influence than provenance. We demonstrate that LT50 in sugar maple can exceed -55°C, far below the minimum temperatures occurring in winter at the northern limit of the species. In order to minimize the risk of damage from extreme frost events exceeding tree frost hardiness, a careful evaluation of site characteristics is more important than provenance selection. Other factors should also be considered within the context of changing climate, in particular the phenology of maple and avoidance of late frost in spring.