Major Climatic Zones Research Articles

Comprehensive performance analysis of cascade refrigeration system with two-stage compression for industrial refrigeration

The cascade refrigeration system with two-stage compression (CRST) with R1150/R717 as the refrigerant group was studied to replace the three-stage cascade refrigeration system (TCRS) with R1150/R41/R717 as the refrigerant group, aiming to improve the operational efficiency of the industrial refrigeration system in the temperature range of −120°C to −80°C. This paper selected typical cities in five major climatic zones in China to analyze the coefficient of performance (COP), annual total power consumption, and seasonal energy efficiency ratio (SEER) of CRST and TCRS under different climatic conditions based on compressor discharge temperature, compressor input power, COP, and thermodynamic perfectibility. According to the results, the compressor input power of CRST is 1.45–1.61 kW lower than that of TCRS. CRST improved by 7.0%–11.7% in terms of COP and thermodynamic perfectibility. The seasonal performance analysis compared the CRST and TCRS operating in five different climate zones; the SEER of CRST increased by 26.3%–29.2%. CRST has a significant energy-saving effect, with an annual total power consumption of 8.6%–10.2% lower than that of TCRS. Finally, in the evaporation temperature range of −120°C to −80°C, the technical scheme of using CRST to replace TCRS in different climate zones is entirely feasible.

An extensive analysis of Codon usage pattern, Evolutionary rate, and Phylogeographic reconstruction in Foot and mouth disease (FMD) serotypes (A, Asia 1, and O) of six major climatic zones of India: A comparative study

Foot and mouth disease (FMD) is a major economically important viral disease of cloven-hoofed livestock globally. The FMD virus (FMDV) spreads widely in confined, cool, and humid climatic conditions. Being an RNA virus, FMDV is genetically unstable, and its genome evolution is highly influenced by mutational pressure. The climatic and environmental conditions have a significant impact on mutational pressure. The present study is a primary effort to establish a comprehensive relationship between climatic factors and the molecular evolutionary pattern of serotypes FMDV circulating in India. In this study, isolates of three serotypes (A, Asia 1, and O) were selected from six major climatic zones of India (Montane, Humid subtropical, Tropical wet and dry, Tropical wet, Semi-arid and Arid). Based on the full genome nucleotide sequence data, the codon usage bias, evolutionary and phylogeographic analysis was carried out. The study revealed that the codon use bias indicators in the FMDV serotypes differed significantly depending on the climatic zones. It implies that the selection and mutational pressure influence the codon usage pattern indices, with mutational pressure taking precedence in determining the codon usage bias of the FMDV genome. The tMRCA was estimated to be 1977, 1956, and 1953 for Indian FMD virus serotype-A, Asia 1, and O respectively which is around 32, 60, and 61 years before its actual identification in the field. Based on the evolutionary rates the serotype O is evolving rapidly compare to other serotypes in India. Virus transmission across the region was evident from the phylogeographic analysis. The integrated analysis of codon usage bias, evolutionary rate, and phylogeography analysis signifies the major role of mutational and selection pressure, implying that the FMD virus co-evolution and adaptations are highly influenced by climatic/environmental factors.

Performance comparison of the single-refrigerant cascade refrigerating system

In the food refrigeration industry, the single-stage compression refrigerating system cannot meet the operating conditions of a high-pressure ratio when the evaporating temperature decreases. The cascade refrigerating system (CRS) is an alternative technical solution to solving the mentioned problem. This paper studied single-refrigerant pairs used in CRS. The single-refrigerant pairs R32/R32, R125/R125, R1270/R1270, R143a/R143a, R404A/R404A, R407A/R407A, R410A/R410A, and R507A/R507A were adopted to evaluate their operating characteristics compared with those of the traditional R23/R404A CRS. The operation adaptability of the compressor, the optimal operating parameters, the coefficient of performance (COP), and the seasonal energy efficiency ratio (SEER) were analyzed under different single-refrigerant pairs. The results show that the COP of the traditional CRS can be improved by using single-refrigerant pairs. The COP of R32/R32, R125/R125, R1270/R1270, R143a/R143a, R404A/R404A, R410A/R410A, and R507A/R507A were improved by 19.48%, 8.08%, 21.54%, 14.33%, 11.00%, 15.64%, and 12.11%, respectively. In addition, the SEER of the single-refrigerant CRS was higher than that of R23/R404A CRS. This could reduce energy consumption and save energy in typical cities in five major climatic zones of China. Considering COP, flammability, and safety, the application of R1270/R1270 and R32/R32 in a CRS with a low refrigerant charge is recommended. Meanwhile, R410A/R410A may be used in a CRS with a large refrigerant charge. These results provide a theoretical basis for the application of the single-refrigerant CRS.

Quantifying the influence of 2D and 3D urban morphology on the thermal environment across climatic zones

Urban heat islands (UHIs) exert a substantially negative impact on human health and urban sustainability. The role of two-dimensional (2D) landscape patterns in UHIs are well documented; while the effects and contributions of three-dimensional (3D) urban structures remain unclear, especially across different climatic zones. Here we investigated the relationship between 2D/3D urban morphology and the urban thermal environment in summer and winter during the day and at night in 62 representative large cities across four major climate zones in China. First, we extracted the seasonal surface regional heat island intensity (SRHII) using the MODIS 8-Day land surface temperature product. Subsequently, we constructed 25 2D and five 3D urban features and explored their relative importance and respective roles in UHIs in different climatic contexts. Results show that: (1) significant differences (p < 0.05) exist in SRHII between various climate zones; cities with a humid subtropical climate experience temperatures approximately 2 °C higher during the day in summer compared to those with the other climate types. (2) 3D urban features can effectively improve the interpretation of urban features for SRHII, with an average optimization level of 21%. (3) Urban trees have a higher cooling effect than other green spaces, whereas tall buildings can also reduce the UHI effect. (4) On summer days, equal proportions of tree to building volume provide the greatest cooling effects. This study provides new insights into the effect of 3D urban characteristics on SRHII and has promising implications for climate resilience planning and heat-related risk management

Feasibility and retrofit guidelines towards net-zero energy buildings in tropical climates: A case of Ghana

Constructing and retrofitting buildings into net-zero energy has become an important strategy for reducing greenhouse gas emissions; however, its implementation remains a critical challenge, particularly with existing buildings retrofit. This study investigates the feasibility and proposes retrofit guidelines that achieve net-zero energy targets for existing buildings in a tropical climate. A two-storey residential building, a typical archetype model in Ghana, was analyzed systematically using parametric simulation. The calibrated model was used to determine energy efficiency interventions and renewable energy potential for achieving Net-Zero Energy Building (NZEB) across four major climate zones. The results showed that passive design strategies such as natural ventilation, sun-shading, daylighting, and envelope airtightness transformed the case building with an Energy Use Intensity (EUI) of 136–138 kWh/m2/yr to 68–70 kWh/m2/yr, therefore reducing 48–50% of total energy demand. Subsequently, a solar PV system was scaled to cover the remaining energy needs with a payback period of 6–10 years, thus transforming the building into NZEB and even to “net-positive energy” (i.e., building generating more energy than it consumes). The study demonstrates that it is feasible to achieve the NZEB target in existing residential buildings in the tropical climate of Ghana. This study’s novelty is that it offers retrofit interventions and adequate retrofit guidelines for renovating residential buildings into NZEBs.

Quantifying the Trends and Variations in the Frost-Free Period and the Number of Frost Days across China under Climate Change Using ERA5-Land Reanalysis Dataset

Understanding the spatio-temporal variations in the frost-free period (FFP) and the number of frost days (FD) is beneficial to reduce the harmful effects of climate change on agricultural production and enhancing agricultural adaptation. However, the spatio-temporal variations in FFP and FD and their response to climate change remain unclear across China. To investigate the impact of climate change on FFP and FD, the trends and variations in FFP and FD across China from 1950 to 2020 were quantified using ERA5-Land, a reanalysis dataset with high spatial and temporal resolution. The results showed that ERA5-Land has good applicability in quantifying the trends and variations in FFP and FD across China under climate change. The spatial distribution of multi-year average FFP and FD across China showed significant latitudinal zonality and altitude dependence, i.e., FFP decreased with increasing latitude and altitude, while FD increased with increasing latitude and altitude. As a result of climate warming across China, the FFP showed an increasing trend with an increase rate of 1.25 d/10a and the maximum increasing rate of FFP in the individual region was 6.2 d/10a, while the FD showed a decreasing trend with a decrease rate of 1.41 d/10a and the maximum decreasing rate of FD in the individual region was −6.7 d/10a. Among the five major climate zones in China, the subtropical monsoon climate zone (SUMZ) with the greatest increasing rate of 1.73 d/10a in FFP, while the temperate monsoon climate zone (TEMZ) with the greatest decreasing rate of −1.72 d/10a in FD. In addition, the coefficient of variation (Cv) of FFP showed greater variability at higher altitudes, while the Cv of FD showed greater variability at lower latitudes in southern China. Without considering the adaptation to temperature of crops, a general increase in FFP and a general decrease in FD were both beneficial to agricultural production in terms of FFP and FD promoting a longer growing period and reducing frost damage on crops. This study provides a comprehensive understanding of the trends and variations in FFP and FD under climate change, which is of great scientific significance for the adjustment of the agricultural production layout to adapt to climate change in China.

COSMOS-Europe: a European network of cosmic-ray neutron soil moisture sensors

Abstract. Climate change increases the occurrence and severity of droughts due to increasing temperatures, altered circulation patterns, and reduced snow occurrence. While Europe has suffered from drought events in the last decade unlike ever seen since the beginning of weather recordings, harmonized long-term datasets across the continent are needed to monitor change and support predictions. Here we present soil moisture data from 66 cosmic-ray neutron sensors (CRNSs) in Europe (COSMOS-Europe for short) covering recent drought events. The CRNS sites are distributed across Europe and cover all major land use types and climate zones in Europe. The raw neutron count data from the CRNS stations were provided by 24 research institutions and processed using state-of-the-art methods. The harmonized processing included correction of the raw neutron counts and a harmonized methodology for the conversion into soil moisture based on available in situ information. In addition, the uncertainty estimate is provided with the dataset, information that is particularly useful for remote sensing and modeling applications. This paper presents the current spatiotemporal coverage of CRNS stations in Europe and describes the protocols for data processing from raw measurements to consistent soil moisture products. The data of the presented COSMOS-Europe network open up a manifold of potential applications for environmental research, such as remote sensing data validation, trend analysis, or model assimilation. The dataset could be of particular importance for the analysis of extreme climatic events at the continental scale. Due its timely relevance in the scope of climate change in the recent years, we demonstrate this potential application with a brief analysis on the spatiotemporal soil moisture variability. The dataset, entitled “Dataset of COSMOS-Europe: A European network of Cosmic-Ray Neutron Soil Moisture Sensors”, is shared via Forschungszentrum Jülich: https://doi.org/10.34731/x9s3-kr48 (Bogena and Ney, 2021).

Discordant phylogeographic patterns between the tortoise tick Hyalomma aegyptium and their Testudo graeca hosts

Tortoise ticks, Hyalomma aegyptium, are considered so strongly associated with their hosts that they are even used as indirect indicators for them. In such a case, a robust pattern of congruence between host and parasite could be expected, with phylogeographic breaks within the host being reflected in their parasites. We sequenced two mitochondrial partial gene regions (12S rRNA and Cytochrome Oxidase 1) from ticks across northern Africa and Anatolia, and compared patterns of variation with those identified in its main host, Testudo graeca. Two distinct haplogroups were identified, both of which were found distributed across much of northern Africa. This pattern does not reflect the known variation within the host, which has multiple, geographically disjunct subspecies in this region, but rather the major climatic zones. This relationship can be explained by adaptive processes to environmental conditions influenced by the climate, as well as by the spatial structure of the communities of tick potential hosts in larval and nymphal stages. Extensive anthropogenic movement of tortoises may also obscure congruence patterns between H. aegyptium ticks and their hosts.

Dynamic simulation of hydrogen-based zero energy buildings with hydrogen energy storage for various climate conditions

Solar energy systems are an effective way to meet the needs of zone heating, cooling, electricity, and domestic hot water. However, to reach sustainability, and energy storage unit should be considered for installation. In this study, two combined cooling, heating and power (CCHP) systems are simulated and studied using TRNSYS software; both using natural gas engine generators and photovoltaics as prime movers and a hydrogen fuel cell/electrolyzer storage unit, one with absorption chiller and another with compression chiller cooling. For the study, a residential building is modeled for three major populated climate zones of the United States of America, namely, Hot-humid, mixed-humid and cold using DesignBuilder and EnergyPlus software. The energy demand for its HVAC operation and domestic electricity is obtained and used for system simulation in TRNSYS software. Due to choosing actual equipment for the CCHP arrangement, precise economic and environmental models are designed to further evaluate the possibility of execution of the system. The results show that absorption chiller-equipped CCHP has better performance both environmentally and economically. In addition, the outcome shows that the suggested systems show less favorability to be utilized in hot humid climate zones.

An Extensive Analysis of Codon Usage Pattern, Evolutionary Rate and Phylogeographic Reconstruction in Foot and Mouth Disease (Fmd) Serotypes (a, Asia 1 and O) of Six Major Climatic Zones of India: A Comparative Study

An Extensive Analysis of Codon Usage Pattern, Evolutionary Rate and Phylogeographic Reconstruction in Foot and Mouth Disease (Fmd) Serotypes (a, Asia 1 and O) of Six Major Climatic Zones of India: A Comparative Study

An Extensive Analysis of Codon Usage Pattern, Evolutionary Rate and Phylogeographic Reconstruction in Foot and Mouth Disease (Fmd) Serotypes (a, Asia 1 and O) of Six Major Climatic Zones of India: A Comparative Study

An Extensive Analysis of Codon Usage Pattern, Evolutionary Rate and Phylogeographic Reconstruction in Foot and Mouth Disease (Fmd) Serotypes (a, Asia 1 and O) of Six Major Climatic Zones of India: A Comparative Study

Spatial differentials in malaria infection among children aged 6 to 59 months in Burkina Faso

Malaria is endemic in Burkina Faso with an upsurge in the rainy season. It is the leading cause of morbidity and mortality in health facilities in the country. Children, especially those aged 6-59 months, constitute the most vulnerable segment of the population. Three major climatic zones modulate its transmission in Burkina Faso and thus create strong spatial disparities. Based on 2017-2018 data from the Burkina Faso Malaria Indicator Survey (EIPBF), this study aims to contribute to the improvement of knowledge on the influence of individual and contextual factors on the spatial differentials of malaria infection in children aged 6-59 months in Burkina Faso. To verify this objective, at the descriptive level the chi2 test will be examined between the malaria attack of the child and each of the independent variables on the one hand, and on the other hand, the profile of the children suffering from malaria will be drawn up thanks to factor analysis and classification. At the explanatory level, this will be possible thanks to the multi-level analysis method. From a multi-level analysis, the results reveal that individual factors have more impact on childhood malaria infection than community factors. These have more impact than family factors. If in the meso-endemic zone, the most important explanatory factors are the place of residence and the age of the child, in the hypo-endemic zone, it is the age of the mother. While for the hyper-endemic zone, religion ranks first. Malaria control interventions should primarily target children aged 24 to 59 months living in rural areas in the meso-endemic zone. In hyper and hypo endemic areas, these interventions should focus on Christian mothers or mothers of other religions and mothers aged 15 to 24 years. Keywords: Child, spatial differentials, malaria, endemic zone, Burkina Faso.

Divergent Causes of Terrestrial Water Storage Decline Between Drylands and Humid Regions Globally

AbstractDeclines in terrestrial water storage (TWS) exacerbate regional water scarcity and global sea level rise. Increasing evidence has shown that recent TWS declines are substantial in ecologically fragile drylands, but the mechanism remains unclear. Here, by synergizing satellite observations and model simulations, we quantitatively attribute TWS trends during 2002–2016 in major climate zones to three mechanistic drivers: climate variability, climate change, and direct human activities. We reveal that climate variability had transitory and limited impacts (&lt;20%), whereas warming‐induced glacier loss and direct human activities dominate the TWS loss in humid regions (∼103%) and drylands (∼64%), respectively. In non‐glacierized humid areas, climate variability generated regional water gains that offset synchronous TWS declines. Yet in drylands, TWS losses are enduring and more widespread with direct human activities, particularly unsustainable groundwater abstraction. Our findings highlight the substantive human footprints on the already vulnerable arid regions and an imperative need for improved dryland water conservation.

Aerosol-modulated heat stress in the present and future climate of India

Heat stress is one of the leading natural causes of mortality in India. Aerosols can potentially impact heat stress by modulating the meteorological conditions via radiative feedback. However, a quantitative understanding of such an impact is lacking. Here, using a chemical transport model, Weather Research Forecasting model coupled with chemistry, we show that high aerosol loading in India was able to mask the heat stress (quantified by the wet bulb globe temperature (WBGT)) by 0.3 °C–1.5 °C in 2010 with a regional heterogeneity across the major climate zones in India. However, the cooling effect of aerosol direct radiative forcing is partially compensated by an increase in humidity. To understand the potential impact of air quality improvement (i.e. reducing aerosol load) on heat stress in the future, WBGT was projected for 2030 under two contrasting aerosol emission pathways. We found that heat stress would increase by >0.75 °C in all the climate zones in India except in the montane zone under the RCP4.5 scenario with a bigger margin of increase in the mitigation emission pathway relative to the baseline emission pathway. On the contrary, under the RCP8.5 scenario, heat stress is projected to increase in limited regions, such as the tropical wet and dry, north-eastern part of the humid sub-tropical, tropical wet, and semi-arid climate zone in peninsular India. Our results demonstrate that aerosols modulate heat stress and, therefore, the heat stress projections in India and anywhere else with high aerosol loading should consider aerosol radiative feedback.

Renewable energy and energy storage to offset diesel generators at expeditionary contingency bases

Expeditionary contingency bases (non-permanent, rapidly built, and often remote outposts) for military and non-military applications represent a unique opportunity for renewable energy. Conventional applications rely upon diesel generators to provide electricity. However, the potential exists for renewable energy, improved efficiency, and energy storage to largely offset the diesel consumed by generators. This paper introduces a new methodology for planners to incorporate meteorological data for any location worldwide into a planning tool in order to minimize air pollution and carbon emissions while simultaneously improving the energy security and energy resilience of contingency bases. Benefits of the model apply not just to the military, but also to any organization building an expeditionary base—whether for humanitarian assistance, disaster relief, scientific research, or remote community development. Modeling results demonstrate that contingency bases using energy efficient buildings with batteries, rooftop solar photovoltaics, and vertical axis wind turbines can decrease annual generator diesel consumption by upward of 75% in all major climate zones worldwide, while simultaneously reducing air pollution, carbon emissions, and the risk of combat casualties from resupply missions.

A New Method to Estimate Heat Exposure Days and Its Impacts in China

Understanding the spatiotemporal trends of temperature in the context of global warming is significant for public health. Although many studies have examined changes in temperature and the impacts on human health over the past few decades in many regions, they have often been carried out in data-rich regions and have rarely considered acclimatization explicitly. The most frequent temperature (MFT) indicator provides us with the ability to solve this problem. MFT is defined as the longest period of temperature throughout the year to which a human is exposed and therefore acclimates. In this study, we propose a new method to estimate the number of heat exposure days from the perspective of temperature distribution and MFT, based on the daily mean temperature readings of 2142 weather stations in eight major climate zones in China over the past 20 years. This method can be used to calculate the number of heat exposure days in terms of heat-related mortality risk without the need for mortality data. We estimated the distribution and changes of annual mean temperature (AMT), minimum mortality temperature (MMT), and the number of heat exposure days in different climate zones in China. The AMT, MMT, and number of heat exposure days vary considerably across China. They all tend to decrease gradually from low to high latitudes. Heat exposure days are closely related to the risk of heat-related mortality. In addition, we utilized multiple linear regression (MLR) to analyze the association between the risk of heat-related mortality and the city and its climatic characteristics. Results showed that the number of heat exposure days, GDP per capita, urban population ratio, proportion of elderly population, and climate zone were found to modify the estimate on heat effect, with an R2 of 0.71. These findings will be helpful for the creation of public policies protecting against high-temperature-induced mortalities.

A mathematical description of evaporative cooling potential for perishables storage in India

Post-harvest losses of fruit and vegetables in India, estimated to be around 30 %, can cause major economic disaster for smallholder farmers. A significant part of these losses occur due to lack of appropriate cold storage facilities, high temperatures, and low RH of ambient air especially during summer months. The high capital required and lack of uninterrupted power supply makes it difficult for farmers to build cold stores and existing cold storages are not distributed equitably and do not have sufficient capacity to serve India's 100 million smallholder farmers. One cooling option is the relatively inexpensive evaporatively cooled (EC) storage, which was designed to enable farmers to avert distress sale and get a fair price for produce. An EC storage, termed the Pusa EC room, was built using novel construction materials including fabric walls and insulative blocks and evaluated year-round over a period of 5 years (2017–2021) using respiratory and senescence responses of amaranth (Amaranthus spp.) to storage temperatures. Wetting of the fabric walls yielded cooling of the structure interior during the daytime, but not at nighttime. As a result of lowered temperatures, storage life was predicted to be nearly doubled relative to storage at ambient temperatures during the warm and dry spring and summer weeks, however it was not improved appreciably when the ambient temperature declined and RH increased during late summer, fall, and winter. The estimated daily reduction in respired CO2 for the leafy amaranth, used here as a model plant, was governed by a simple mathematical expression using wet bulb depression of temperature relative to ambient. The predictive equation can be applied to any plant material for which the metabolic response to temperature is defined and permits convenient estimation of the benefits of evaporative cooling, potentially anywhere on the globe. This relationship was used for predicting storage-life improvement for many cities of major climate zones in India using data retrieved from website https://en.climate-data.org. EC room benefits were projected to be highest for warmer, drier climates, as would be expected; however, regional climate classifications were not always found to be a good guide for siting EC rooms due to local and microclimate variability.

Impacts of temperature and humidity changes on air‐conditioning design load under the climate change conditions in different climate zones of China

AbstractMeteorological parameters, as the important basis for improving building energy efficiency, will show apparent changes under climate change conditions. In this study, outdoor design temperature and humidity for air‐conditioning system in 12 cities, representing major climatic zones of China, were analysed to determine the impacts of temperature and humidity on the design load of air‐conditioning system. The results showed that outdoor design temperature largely increased during the last few decades and relative humidity apparently decreased except for two cities belonging to the severe cold and hot summer and cold winter climate zones. The increase in temperature and decrease in humidity have made obvious changes in the design load of air‐conditioning system. The design loads for cooling increased 1.8%–10% in these selected cities during 1991–2017 compared with 1961–1990. By contrast, the design loads for dehumidification decreased 0.8%–7% in 1991–2017 relative to 1961–1990. When the cooling and dehumidification were considered together, the design loads changed from −1.5% to 4.1% in the two periods, depending on cities or climate zones. These results demonstrated that, under the condition of climate change, the combined changes of humidity and temperature rather than temperature alone should be fully considered to determine the design capacity of air‐conditioning system, especially for temperature and humidity independent control (THIC) air‐conditioning system, to save energy and improve indoor comfort.

Impacts of forest loss on local climate across the conterminous United States: Evidence from satellite time-series observations

Forest disturbances alter land biophysics. Their impacts on local climate and land surface temperature (LST) cannot be directly measured by comparing pre- and post-disturbance observations of the same site over time (e.g., due to confounding such as background climate fluctuations); a common remedy is to compare spatially-adjacent undisturbed sites instead. This space-for-time substitution ignores the inherent biases in vegetation between two paired sites, interannual variations, and temporal dynamics of forest recovery. Besides, there is a lack of observation-based analyses at fine spatial resolutions capable of capturing spatial heterogeneity of small-scale forest disturbances. To address these limitations, here we report new satellite analyses on local climate impacts of forest loss at 30 m resolution. Our analyses combined multiple long-term satellite products (e.g., albedo and evapotranspiration [ET]) at 700 sites across major climate zones in the conterminous United States, using time-series trend and changepoint detection methods. Our method helped isolate the biophysical changes attributed to disturbances from those attributed to climate backgrounds and natural growth. On average, forest loss increased surface albedo, decreased ET, and reduced leaf area index (LAI). Net annual warming—an increase in LST—was observed after forest loss in the arid/semiarid, northern, tropical, and temperate regions, dominated by the warming from decreased ET and attenuated by the cooling from increased albedo. The magnitude of post-disturbance warming was related to precipitation; climate zones with greater precipitation showed stronger and longer warming. Reduction in leaf or LAI was larger in evergreen than deciduous forests, but the recovery in LAI did not always synchronize with those of albedo and ET. Overall, this study presents new evidence of biophysical effects of forest loss on LST at finer spatial resolutions; our time-series method can be further leveraged to derive local policy-relevant ecosystem climate regulation metrics or support model-based climate-biosphere studies.

Middle Pleistocene Variations in the Diet of Equus in the South of France and Its Morphometric Adaptations to Local Environments

Equus is a very sensitive genus which has expanded over a large area and lived in Europe despite the climatic instability of the Pleistocene. Its persistence and abundance are helpful in understanding and describing environmental and climatic regional parameters. In this study, we present the result of dental mesowear and microwear analysis and post-cranial skeleton biometry on Equus populations located in two regions in the South of France from ten sites, corresponding to twelve assemblages dated from MIS 12 to MIS 5. The areas refer to two major climatic zones: the oceanic or subcontinental climate for the South West of France, and the Mediterranean for the South East. The first objective of this study is to integrate and compare biometric data, dental wear, and other already-published environmental proxies. The goal is to discuss the validity of horse body shape adaptations on a small geographical scale. The second objective is to describe the impact of environmental features on the horse population through time in the two regions. We observe that the Equus diet was quite diverse, according to microwear analysis which shows adaptations according to seasonal variations. However, they remained mostly grazers over a long period of time. Estimated body mass of Equus in the localities studied here varies from a mean of 468 up to a mean of 570 kg, but these variations failed to be correlated with the diet, the climatic period, or the geographical position of the horse population, probably because of the sample size or the restricted time-span or geographical scale. However, the conformation of the metapodials and the width of the third phalanges may have been linked with environmental and behavioural parameters. The width of the third phalange may be correlated with the recurrence of the snow cover, while the robustness of the metapodial co-occurs with a humid climate. Also, diet may influence the conformation of the bones, since the tall and slender horses seem to be preferentially grazers all year long and seasonally browser horses are tall and robust. Seasonally mixed-feeder horses, all coming from the Mediterranean area, were found to be smaller, perhaps in relation to a less productive environment. The correspondence of the dietary and morphometrical data could suggest high pressure on the horse population, which caused rapid body adaptation. Thus, the combination of these different proxies allows us to suggest more accurate large mammal paleoenvironmental reconstructions.