Mean Annual Temperature Research Articles

Grazing exclusion promotes soil organic carbon accumulation in Tibetan grasslands with lower temperatures

BackgroundGrazing exclusion is a practical approach to restore vegetation in degraded grasslands and enhance soil organic carbon (SOC) sequestration. However, the dynamics and drivers of SOC in grasslands after grazing exclusion have not been well documented, especially in ecosystems with cold climates.MethodsHere, we established 14 paired treatments (grazing exclusion vs. free-grazing) along a 600-km transect in the northeastern zone of the Qinghai-Tibet Plateau. After six years, we analyzed vegetation biomass dynamics and measured the soil physicochemical properties and organic C concentration across three depths (0–10, 10–20, and 20–30 cm).ResultsGrazing exclusion significantly increased above- and belowground biomass (139.85% and 43.30%, respectively), pH (1.38%), total phosphorus (3.29%), nitrate nitrogen (18.03%), and ammonium nitrogen (17.81%), but significantly decreased soil bulk density (2.43%) and clay content (10.49%), particularly in 0–30 cm. Specifically, SOC concentrations positively responded to grazing exclusion (0–10 cm) in 9 of the 14 sites evaluated. The effects of grazing exclusion on SOC concentrations were significantly higher in areas with a mean annual temperature (MAT) below 0 °C compared to those in sites with a high MAT (> 0 °C). The SOC concentrations significantly correlated with the mean annual precipitation (MAP) in both treatments, but these correlations diminished with increasing soil depth. Ridge regression analysis showed that soil chemical properties (e.g., total nitrogen and phosphorus) positively influenced SOC accumulation, while MAT negatively influenced it after grazing exclusion. Path analysis further revealed that MAT indirectly regulated SOC dynamics via soil chemical properties.ConclusionsOur study highlights that grazing exclusion results in an asynchronous SOC and plant biomass accumulation and may be more beneficial for SOC sequestration in Qinghai-Tibet Plateau grasslands with lower temperatures. Also, humid climates promote SOC concentration in alpine grasslands. These results could help develop management practices and policies that promote sustainable grassland management.

Spatio-temporal trends in the frost regime reveal late frost exposure to white spruce (Picea glauca [Moench] Voss) persists in northeastern America

Abstract The characteristics of the frost regime (intensity, frequency, and timings) contributed to shaping tree species adaptations and distribution as well as ecosystem productivity and functions. However, climate change increased the variability in extreme events; therefore, the different characteristics of the frost regime may diverge under climate change. Using the BioSim 11 software, we simulated daily air temperature at 512 locations over Eastern Canada between 1901-2021 to determine how the spatio-temporal trends in the frost regime varied over this complex landscape and if spatio-temporal trends in extreme climatic events such as frosts are stronger compared to changes in aggregated climate variables such as mean annual temperature and growing degree-days. We also used an eco-physiological model to conduct a study case focussing on white spruce to determine if trees are currently more exposed to growing season frosts than they were in the past by modelling the timings of budburst using the thermal time model. Our results showed that, at 353 sites, the day of the year of the last frost in spring (minimum daily air temperature < 0 °C) occurred, on average, earlier by seven days during 2001-2021 compared to 1901-1920, whereas it occurred, on average, later by five days at 159 sites. The average temporal trends in frost occurrence were similar in magnitude to the average trends in aggregated climate variables; however, their variances were larger compared to the aggregated climate metrics, showing that the frost regime does not change uniformly throughout our study area. Our study case also revealed that white spruce remains exposed to late frosts of low and intermediate intensities (minimum daily air temperature < 0; < -2 °C) compared to the past but is almost not exposed to late frosts of high intensity (minimum daily air temperature < -4 °C). Since extreme events such as late frosts diverge in their response to climate change compared to aggregated climate variables, the mean annual temperature is not sufficient to predict how climate change will impact ecosystems through frost regimes.

Spatial and climatic drivers of β‐diversity in assemblages of angiosperm genera across the world

Abstract β‐diversity quantifies the change in taxonomic and phylogenetic composition between areas. It can be partitioned into two additive components (turnover and nestedness). Geographic distance, which reflects dispersal limitation, and climatic distance, which reflects environmental filtering, are major drivers of β‐diversity, but few studies have assessed their relative importance to β‐diversity at a global scale. Here, we investigate the relationship of β‐diversity of angiosperm genera in regional floras worldwide to climatic conditions within regions and to geographic and climatic distances between regions. We found that (1) current climate has a stronger effect on phylogenetic turnover than does Quaternary climate change; (2) of the current climate variables examined, mean annual temperature is the strongest driver of phylogenetic turnover, followed by precipitation seasonality; (3) regions with high precipitation seasonality have high phylogenetic β‐diversity and phylogenetic turnover; and (4) at a global scale, the variation in phylogenetic turnover explained jointly by geographic and climatic distances is, on average, much larger than that explained uniquely by either distance, but that geographic distance explains more variation in phylogenetic turnover than climatic distance. Synthesis. These results reveal the synergistic role of geographic isolation and climatic filtering in determining the composition of floras worldwide, with less influence of Quaternary climate changes.

Predicting the habitat suitability and species richness of plants of Great Himalayan National Park under different climate change scenarios.

This study elucidates the distribution of plants in Great Himalayan National Park (GHNP), India, in current and different future climate change scenarios. The distribution of plants and habitat suitability in GHNP due to climate change was analyzed by MaxEnt, species distribution model (SDM) algorithm. In this study, species presence records were retrieved through field survey and published literature. We have projected the distribution of 44 plant species using MaxEnt and tested whether GHNP is performing well in conserving the plant species. Initially, we have constructed a model for each species and created the habitat suitability map from average of ascii files and later we added the maps of all species in order to make binary map to show the species richness in the selected climate scenarios. The model was created using the HADGEM-2 global circulation model in 2050 and 2070years by using climate change situations of RCP 2.6 and RCP 8.5. The area under curve (AUC) values in the final models of 44 plant species were in the range 0.70-0.97 that indicates statistically significant results. The model identified precipitation of driest month followed by altitude and annual mean temperature as most determining variables in the distribution of plants of GHNP in selected climate scenarios. In the present study, we found that overall suitable habitat increased for nine species, decreased for thirty-four, and unchanged for one plant species in terms of percent area change from current to future scenarios. So these nine species were found to be more adaptable towards changing climate than the other plant species in this study. The species richness was high in western and southwestern parts of GHNP in the current scenario, however under future climatic scenarios, species richness shows a decreasing trend. Based on our findings, it can be concluded that GHNP should be prioritized for conserving the plant species.

Potential to recover a record of Holocene climate and sea ice from Müller Ice Cap, Canada

Abstract Müller Ice Cap sits on Umingmat Nunaat (Axel Heiberg Island), Nunavut, Canada, ~ 80°N. Its high latitude and elevation suggest it experiences relatively little melt and preserves an undisturbed paleoclimate record. Here, we present a suite of field measurements, complemented by remote sensing, that constrain the ice thickness, accumulation rate, temperature, ice-flow velocity, and surface-elevation change of Müller Ice Cap. These measurements show that some areas near the top of the ice cap are more than 600 m thick, have nearly stable surface elevation, and flow slowly, making them good candidates for an ice core. The current mean annual surface temperature is −19.6 °C, which combined with modeling of the temperature profile indicates that the ice is frozen to the bed. Modeling of the depth-age scale indicates that Pleistocene ice is likely to exist with measurable resolution (300–1000 yr m−1) 20–90 m from the bed, assuming that Müller Ice Cap survived the Holocene Climatic Optimum with substantial ice thickness (~400 m or more). These conditions suggest that an undisturbed Holocene climate record could likely be recovered from Müller Ice Cap. We suggest 91.795°W, 79.874°N as the most promising drill site.

Late-Holocene hydroclimatic change and its effect on human activity at Xiada Co on the western Tibetan Plateau

The scarcity of paleoclimate records in the western Tibetan Plateau (TP) hinders our understanding of how environmental evolution affects past human population, agriculture, and animal husbandry. Here, we utilized a range of materials to investigate the impact of climate change on human activities in the Xiada Co basin on the western TP during the Late-Holocene. We presented a continuous compound-specific hydrogen isotope record of sedimentary leaf waxes (δ2Hwax) from a sediment core of Xiada Co, and compared it to XRF core-scanning elements, brGDGT-based mean annual air temperature (MAAT) record, and fecal stanol-based human population proxy record from the same sediment core, as well as archeological evidence from the TP. The δ2Hwax exhibited a sustained increasing trend during the period from 4700 to 900 cal yr BP, followed by a generalized decrease in δ2Hwax values during 900–0 cal yr BP. The multi-proxy analysis of Xiada Co sediments revealed that the δ2Hwax values mainly reflect changes in the ISM precipitation, and are also influenced to some extent by glacier meltwater. Furthermore, a warm and humid climate condition was conducive to human habitation. Appropriate adaptation strategies, such as the herding of cold-tolerant and dry-tolerant sheep and the cultivation of barley in the western TP, led to a surge in population density during 3400–2900 cal yr BP, despite the slightly deteriorated climate background. This study confirmed the importance of choosing the right adaptive strategies to cope with climate change for human survival and development on the Tibetan Plateau.

Shifting cold regions streamflow regimes in North America affect flood frequency analysis

ABSTRACT Over threshold flood events in seventy years of data from 202 reference hydrometric stations in Canada and the United States were separated into nival, mixed, and pluvial flood types. While Mann-Kendall trend tests showed few significant trends in flood magnitude, significant changes in flood type fraction were found over time, with annual mean temperature, and with annual precipitation. Nival events decreased in frequency over the seventy-year period in 16% of sites, while mixed and pluvial events increased (5%, 12%). These changes indicate a shift from nival events towards more pluvial dominated systems. Fewer significant changes in flood type fraction were found with analysis against four climate indices. Flood frequency analysis using a combined distribution approach with the three flood types resulted in larger magnitude design flow estimates (median increase of 20 – 30 %) in comparison with the results from considering the data to be a single population.

Macro- and micro-geographic genetic variation in early fitness traits in populations of maritime pine (Pinus pinaster Ait.).

Assessing adaptive genetic variation and its spatial distribution is crucial to conserve forest genetic resources and manage species' adaptive potential. Macro-environmental gradients commonly exert divergent selective pressures that enhance adaptive genetic divergence among populations. Steep micro-environmental variation might also result in adaptive divergence at finer spatial scales, even under high gene flow, but it is unclear how often this is the case. Here, we assess genetic variation in early fitness traits among distant and nearby maritime pine (Pinus pinaster Ait.) populations, to investigate climatic factors associated with trait divergence, and to examine trait integration during seedling establishment. Open pollinated seeds were collected from seven population pairs across the European species distribution, with paired populations spatially close (between <1 km up to 21 km) but environmentally divergent. Seeds were sown in semi-natural conditions at three environmentally contrasting sites, where we monitored seedling emergence, growth and survival. At large spatial scales, we found significant genetic divergence among populations in all studied traits, with certain traits exhibiting association with temperature and precipitation gradients. Significant trait divergence was also detected between pairs of nearby populations. Besides, we found consistent trait correlations across experimental sites, notably heavier seeds and earlier seedling emergence were both associated with higher seedling survival and fitness over two years in all experimental conditions. We identified mean annual temperature and precipitation seasonality as potential drivers of P. pinaster population divergence in the studied early-life traits. Populations genetically diverge also at local spatial scales, potentially suggesting that divergent natural selection can override gene flow along local-scale ecological gradients. These results suggest the species exhibits substantial adaptive potential that has allowed it to survive and evolve under contrasting environmental conditions.

MaxEnt modeling of Klebsiella pneumoniae: predicting future distribution and evaluating the risk for public health

Klebsiella pneumoniae is a Gram-negative bacterium known for causing infections such as pneumonia, urinary tract infections, and bloodstream infections in humans. Its increasing drug resistance poses a significant threat. Understanding the effects of climate change on this bacterium is crucial to managing its impacts effectively. In this study, we employed MaxEnt modeling to explore the current and future distribution of K. pneumoniae under different climate change scenarios for 2050 and 2070. Our models utilized 280 valid occurrence points and 19 bioclimatic variables, with Mean Annual Temperature and Mean Annual Precipitation being the most influential variables. The models demonstrated high accuracy, with an AUC of 0.889. Our findings revealed that K. pneumoniae has a cosmopolitan distribution, with the highest suitability observed in Southeastern Asia, Central Africa, and Southern Europe. Future predictions indicated an apparent expansion of its range across almost all continents, particularly in the RCP 8.5 2070 scenario. Results have crucial implications for epidemiology, as they enable the identification of current and potential future disease hotspots and geographical patterns. This knowledge can inform the development of effective infection control strategies. Furthermore, it provides valuable insights for decision-makers and policymakers in allocating resources efficiently for medical control and prevention strategies.

Expert elicitation of state shifts and divergent sensitivities to climate warming across northern ecosystems

Northern regions are warming faster than the rest of the globe. It is difficult to predict ecosystem responses to warming because the thermal sensitivity of their biophysical components varies. Here, we present an analysis of the authors’ expert judgment regarding the sensitivity of six ecosystem components – permafrost, peatlands, lakes, snowpack, vegetation, and endothermic vertebrates – across northern landscapes ranging from boreal to polar biomes. We identified 28 discontinuous component states across a 3700 km latitudinal gradient in northeastern North America and quantified sensitivity as the transition time from an initial to a contrasting state following a theoretical step change increase in mean annual air temperature of 5 °C. We infer that multiple interconnected state shifts are likely to occur within a narrow subarctic latitudinal band at timescales of 10 to more than 100 years, and response times decrease with latitude. Response times differ between components and across latitudes, which is likely to impair the integrity of ecosystems.

Long-term Holocene warming trend in Southern China revealed by corrected pollen data

Holocene temperature changes and their forcings serve as pivotal references for current and future warming trends. However, significant discrepancies exist between proxy reconstructions and model simulations of Holocene temperature evolution. Pollen evidence, often central to these discrepancies, have been criticized for potentially reflecting human influence rather than pure temperature variations, complicating our understanding of Holocene temperature changes. Our study focuses on southern China, a region with pronounced discrepancies between models and proxies. We introduce and validate a novel methodology to isolate genuine temperature signals from pollen data. This approach employs an arboreal pollen-based temperature index and correct biases inherent in raw pollen data using the Regional Estimates of Vegetation Abundance from Large Sites (REVEALS) model. Applying this method, we present a new winter/annual temperature record for the past 10,000 years based on two fossil pollen data from the Luoxiao Mountains. Simultaneously, we reconstruct the historical impact of human activities in the region. Our temperature records reveal a sustained warming trend during the Holocene, closely matching model-simulated mean annual temperatures (R = 0.97), and temperature reconstructions based on branched glycerol dialkyl glycerol tetraethers from regional terrestrial and marine archives. In contrast, uncorrected pollen data indicate a cooling trend during the late Holocene, coinciding with significant human impact since approximately 3 ka BP. Our analysis and regional comparison with existing temperature records indicate that such contrasting temperature trends stem from a human-induced cooling bias, particularly pronounced in uncorrected pollen data. We infer that the early to middle Holocene warming was due to various factors, while late Holocene warming was predominantly driven by local annual insolation changes. Our findings challenge previously widely identified late-Holocene cooling trends based on uncorrected pollen data, demonstrating that the correction of pollen data can effectively mitigate human-induced cooling biases in temperature reconstructions. This study confirms the accuracy of climate models in simulating a Holocene warming trend, both temporally and spatially, at least in southern China.

Cross-continental comparison of plant reproductive phenology shows high intraspecific variation in temperature sensitivity

Abstract The success of plant species under climate change will be determined, in part, by their phenological responses to temperature. Despite the growing need to forecast such outcomes across entire species ranges, it remains unclear how phenological sensitivity to temperature might vary across individuals of the same species. In this study, we harnessed community science data to document intraspecific patterns in phenological temperature sensitivity across the multicontinental range of six herbaceous plant species. Using linear models, we correlated georeferenced temperature data with 23,220 plant phenological records from iNaturalist to generate spatially-explicit estimates of phenological temperature sensitivity across the shared range of species. We additionally evaluated the geographic association between local historic climate conditions (i.e. mean annual temperature and interannual variability in temperature) and the temperature sensitivity of plants. We found that plant temperature sensitivity varied substantially at both the interspecific and intraspecific level, demonstrating that phenological responses to climate change have the potential to vary both within and among species. Additionally, we provide evidence for a strong geographic association between plant temperature sensitivity and local historic climate conditions. Plants were more sensitive to temperature in hotter climates (i.e., regions with high mean annual temperature), but only in regions with high interannual temperature variability. In regions with low interannual temperature variability, plants displayed universally weak sensitivity to temperature, regardless of baseline annual temperature. This evidence suggests that pheno-climatic forecasts may be improved by accounting for intraspecific variation in phenological temperature sensitivity. Broad climatic factors such as mean annual temperature and interannual temperature variability likely serve as useful predictors for estimating temperature sensitivity across species’ ranges.

Factors contributing to organelle genomes size variation and the intracellular DNA transfer in Polygonaceae

The use of complete organelle genomes, including chloroplast and mitochondrial genomes, is a powerful molecular method for studying biological evolution and gene transfer. However, in the case of Polygonaceae, an important family with numerous edible, medicinal, and ornamental species, the mitochondrial genomes of only three species have been sequenced and analyzed. In this study, we present the mitochondrial and chloroplast genomes of two important Tibetan medicinal plants, Bistorta viviparum and B. macrophyllum. All the organelle genomes are assembled into a single circular structure and contain a common set of 32 protein-coding genes (PCGs). Some genes such as rps2 and ndhF were found to have high nucleotide polymorphism (Pi) in the chloroplast genomes, while cox1, mttB and rps12 showed pronounced Pi values in the mitochondrial genomes. Furthermore, our analysis revealed that most chloroplast genes and mitochondrial PCGs in Polygonaceae plants are under purifying selection. However, a few genes, including the chloroplast gene psaJ and the mitochondrial genes ccmFc, atp8 and nad4, showed positive selection in certain Polygonaceae plants, as indicated by a Ka/Ks ratio greater than one. Structural variation analysis revealed a wealth of differences between the mitochondrial genomes of five Polygonaceae species, with a particularly notable large-scale inversion observed between Reynoutria japonica and Fallopia aubertii. Furthermore, an analysis of the homologous sequences in the chloroplast and mitochondrial genomes revealed that the rps7 has been transferred from the chloroplast to the mitochondrial genome in all five Polygonaceae species. Finally, ecological niche models were constructed for B. viviparum and B. macrophyllum, indicating that mean annual temperature and altitude are the main climatic factors influencing the distribution of both species. Although the current distribution of B. viviparum is significantly wider than that of B. macrophyllum, projections suggest that the optimal growth ranges of both species will expand in the future, with B. macrophyllum potentially exceeding B. viviparum. This study not only contributes to the plastid genome database for Polygonaceae plants, but also provides theoretical insights into the adaptive evolution of these plants.

Performance Evaluation of CMIP6 Climate Model Projections for Precipitation and Temperature in the Upper Blue Nile Basin, Ethiopia

The projection and identification of historical and future changes in climatic systems is crucial. This study aims to assess the performance of CMIP6 climate models and projections of precipitation and temperature variables over the Upper Blue Nile Basin (UBNB), Northwestern Ethiopia. The bias in the CMIP6 model data was adjusted using data from meteorological stations. Additionally, this study uses daily CMIP6 precipitation and temperature data under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios for the near (2015–2044), mid (2045–2074), and far (2075–2100) periods. Power transformation and distribution mapping bias correction techniques were used to adjust biases in precipitation and temperature data from seven CMIP6 models. To validate the model data against observed data, statistical evaluation techniques were employed. Mann–Kendall (MK) and Sen’s slope estimator were also performed to identify trends and magnitudes of variations in rainfall and temperature, respectively. The performance evaluation revealed that the INM-CM5-0 and INM-CM4-8 models performed best for precipitation and temperature, respectively. The precipitation projections in all agro-climatic zones under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios show a significant (p &lt; 0.01) positive trend. The mean annual maximum temperature over UBNB is estimated to increase by 1.8 °C, 2.1 °C, and 2.8 °C under SSP1-2.6, SSP2-4.5, and SSP5-8.5 between 2015 and 2100, respectively. Similarly, the mean annually minimum temperature is estimated to increase by 1.5 °C, 2.1 °C, and 3.1 °C under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. These significant changes in climate variables are anticipated to alter the incidence and severity of extremes. Hence, communities should adopt various adaptation practices to mitigate the effects of rising temperatures.

Altitude and ground brightness explain interpopulation variation in dorsal coloration in a lizard

Abstract Non-signaling functions of coloration include thermoregulation (thermal melanism hypothesis), protection against ultraviolet radiation (photoprotection hypothesis), and concealment from predators (crypsis hypothesis). We investigated whether dorsal coloration in 19 populations of spiny-footed lizards, Acanthodactylus erythrurus, across the Iberian Peninsula varies according to these functions. We captured adult males and females in each population and calculated standardized dorsum brightness estimates from photographs. We also calculated standardized ground luminosity estimates and gathered information on latitude, altitude, mean annual temperature, and mean annual solar radiation for each location. Males showed a higher percentage of black coloration and a more contrasted dorsum than females, suggesting different selection pressures on dorsal coloration in both sexes. Furthermore, males showed a darker dorsum and a higher percentage of black coloration at higher altitudes and when the ground was darker. In contrast, females exhibited a darker dorsum only when the ground was darker and a higher percentage of black coloration only at higher altitudes. We also observed that the variation of dorsum luminosity within males and the variation of dorsum luminosity among females within populations were both positively related to the variation of ground luminosity among different points within locations. Latitude, temperature, and solar radiation were not significantly related to dorsal coloration in either sex. Our results support the photoprotection and crypsis hypotheses in males and, to some extent, in females, whereas the thermal melanism hypothesis is weakly supported in both sexes. These findings suggest that there is local adaptation in the dorsal coloration of the spiny-footed lizard.

Distribution of Najadaceae Species in Trans-Baikal Area Due to Climatic Factors

According to data of the late 20th century in the Trans-Baikal and Baikal areas, the family Najadaceae is represented by four species known in few localities: Caulinia flexilis (4 localities), C. minor (3), and Najas major (3), N. marina (4). All of them are annuals, r-strategists, which are characterized by fluctuations in abundance. Since the 21st century, these species have been found in 20 more localities, mainly situated within the Baikal Depression. In 2015, when performing monitoring studies of aquatic flora, three more new localities of Caulinia flexilis, C. minor, and Najas major were found in the basin of the Amur River. Distribution maps of the Najadaceae species in the region were compiled, and the ecological characteristics of their habitats were given. In Trans-Baikal area, since the middle of the 20th century, warming has occurred due to an increase in the average annual temperature. For the last 70 years, aridization has increased in southern regions, which changes the habitat conditions in waterbodies. Findings of these Najadaceae species in Trans-Baikal area coincided with the periods of increase in mean annual air temperatures and with local minimums of precipitation. An increase in the number of findings of the Najadaceae species since the beginning of the 21st century, both in Trans-Baikal area and in other regions of Russia, has been occurring against the background of an increase in the average annual air temperature. In Trans-Baikal area, the trend of increasing of temperatures in the warm season since the beginning of the 21st century is favorable for these species and may contribute to their further distribution.

The Effect of Climate Change on Indicator Wetland Insects: Predicting the Current and Future Distribution of Two Giant Water Bugs (Hemiptera: Belostomatidae) in South Korea.

Giant water bugs (Hemiptera: Belostomatidae) are top predators in wetland ecosystems, serving as biological indicators of the health of lentic ecosystems and as effective biological control agents for freshwater snails and mosquitoes. This study aimed to predict the current and future distribution of two Korean giant water bugs, Appasus japonicus and Diplonychus esakii, under three climate change scenarios, contributing to the sustainable management of wetland ecosystems in South Korea. Using MaxEnt models, we employed seven climatic and three non-climatic variables to investigate the habitat preferences and distribution patterns of the species. The results revealed that A. japonicus is likely to experience a northward range contraction due to climate change, while D. esakii is predicted to expand its distribution northward without losing its current range. These responses may lead to occupancy turnover between the two species, potentially driving reassembly in aquatic organism community. Elevation was the primary factor influencing the distribution of A. japonicus, whereas annual mean temperature was the most informative variable for D. esakii, both factors derived under the current climate conditions. These findings suggest that both species are highly sensitive to climate change, with potential range shifts toward higher latitudes and elevations. This study provides insights into how climate change could impact two giant water bugs, thereby supporting future efforts to manage and conserve wetland ecosystems in this country.

Establishment of characteristic fingerprint of volatile components in Batocera horsfieldi (Coleoptera: Cerambycidae) host plants and correlation analysis with climatic factors.

Batocera horsfieldi is the primary stemboring pest of timber forests and economic forests in China, belonging to the Coleoptera Cerambycidae. In this study, gas chromatography-mass spectrometry was used to analyze the volatile components in the supplementary feeding hosts and oviposition hosts of B. horsfieldi, and characteristic fingerprints were constructed. A total of 168 compounds were detected, primarily consisting of terpenes, hydrocarbons, and aldehydes, with 75, 23, and 14 compounds, respectively. Hierarchical cluster analysis and principal component analysis yielded consistent results. The similarity evaluation results showed that the similarity range between healthy poplar tree bark and healthy poplar leaves was the highest, reaching 0.953-0.98, and 10 common peaks were identified. The analysis of the correlation with climatic factors shows that most compounds are positively correlated with mean annual humidity, mean annual temperature, mean annual minimum temperature, and mean annual maximum temperature. Only caryophyllene and alpha-guaiene are negatively correlated with temperature-related climatic factors. Pathway analysis also reveals differences in the direct effects of different compounds. These analytical results provide a theoretical basis for further studying the selection mechanism of B. horsfieldi on hosts and offer theoretical guidance for identifying plant-derived attractants with biological activity.

THE IMPACT OF EXTREME WEATHER EVENTS OF PROJECTED CANADIAN REGIONAL CLIMATE MODEL DATA ON FLEXIBLE PAVEMENT

This paper presents findings about the influence of projected data from the Canadian regional climate model on the performance of flexible pavement, building upon the results from previous work where the data was generated and published, in which a general trend of decreasing the design life was observed. Projected temperature is the most important extreme climate impact on flexible roads. Adopting a conservative approach demonstrated that two extreme events of Maximum Mean Annual Air Temperature (MMAAT) and Maximum Summer Average Air Temperature (MSAAT) resulted in significant reduction of 25 years road design life. The observed trend indicates a severity range of 7% to 15% in terms of design service life loss when considering events every year compared to every five years. The findings revealed a reduction in pavement design life by 34%, 50%, 73%, and 90% for historical, short, intermediate, and long-term life cycles in the city of Windsor, respectively.

Geographical variation and genetic diversity of Parashorea chinensis germplasm resources.

Parashorea chinensis is a rare monodominant species in southwest China known for its production of high-quality timber, is facing decline due to its narrow distribution, human interference and habitat destruction. However, there are no reports on genetic diversity and geographical variation of phenotypic traits of P. chinensis. In this study, phenotypic characters and genetic diversity of 15 germplasms resources from five provenances in southwest China were investigated, and their relationships with geographical and environmental factors was discussed. Our results revealed a rich phenotypic diversity among the germplasms, with variation coefficients ranging from 3.63% to 45.49%. Among the studied germplasms, NP03 from Napo and ML02 from Mengla region exhibited superior phenotypic traits. Notably, NP03 also demonstrated the highest genetic diversity. Genetic differentiation analyses including genetic differentiation coefficient (0.6264) and gene flow (0.3736) illustrated that genetic variation was most prevalent among populations. Furthermore, redundancy analysis showed that temperature related factors (maximum air temperature, annual mean temperature and minimum air temperature) significantly affected phenotypic variation. Similarly, altitude, longitude, latitude, annual mean precipitation and the minimum air temperature significantly impacted the level of genetic diversity. The molecular variation of the natural population of P. chinensis followed a certain geographical pattern. Our finding indicated abundant phenotypic variation among P. chinensis germplasms. However, populations exhibited low levels of genetic diversity alongside high genetic differentiation, potentially contributing to the species' rarity. Based on our results, NP03 and ML02 germplasm could be used as the parents for breeding superior germplasm of P. chinensis. Overall, this study provides valuable insights into germplasm diversity and conservation, genetic improvement, and utilization of P. chinensis.