De Martonne Index Research Articles

Aridity in the Iberian Peninsula (1960–2017): distribution, tendencies, and changes

Aridity is a climatic characteristic that has a significant impact on many aspects of life, mainly in agriculture but also in other economic sectors, and temperature and precipitation are the variables by which the effects of aridity can be measured. It is necessary to know its distribution and trend in different climate change scenarios. The Iberian Peninsula presents a strong contrasting climate, comprising both humid and very dry regions. Forty-five climatic time series were used to perform a spatial and temporal analysis and to identify possible points of trend change in annual aridity for the period from 1960 to 2017. Two indices were considered: the De Martonne Index (IDM) and the Food and Agriculture Organisation (FAO) Index (IF). By means of ordinary kriging, maps of spatial, temporal, and trend distributions were made. The trends of the aridity indices, annual temperature, and annual precipitation were analysed by applying the techniques of the modified Mann-Kendall test and Sen’s estimator; furthermore, to identify gaps of years in the series, the Buishand range test was used. The results showed a significant average annual temperature increase at all stations. Although annual precipitation decreased across the board, this decrease was not significant. Semi-arid was the dominant class, although the study area showed great variability, i.e. from extremely humid areas to arid zones. Forty-one out of the 45 series presented increasing aridity during the study period, although the trend was significant in only 16 of the series. From the Buishand range test for both aridity indices, the results revealed a noteworthy changing point for IDM and for IF. Although the changing point was variable, it was concentrated around the late 1970s and early 1980s, and from that period, the aridity tendency was dependent on the analysed series.

The economic impacts of climate change on agriculture in Iran: ‎a CGE model analysis

ABSTRACTIn the following, the impacts of climate change on agricultural sector are analyzed through partial ‎equilibrium model and the effects of climate change scenarios on this section will be measured ‎separately. To this end, the data of value added, labor and capital in the agricultural sector between ‎‎1991 and 2014 are derived from the Central Bank and National Statistics Portal. De Martonne ‎index, which represents the climatic condition, is estimated using precipitation and temperature data ‎extracted from the Meteorological Organization of Iran sector between 1991 and 2014. The current study measured the effects of climate change on the agricultural sector in Iran. For this purpose, the function of agricultural sector production, which is affected by climate (temperature and precipitation), was estimated using the ARDL approach; then, the effect of climate change on the agricultural sector was evaluated in the framework of the SAM model. Different scenarios were applied. In general, it can be concluded that improving the climate will increase the country‘s economic potential and reduce costs, while adverse climate conditions will worsen the country‘s economic situation and, consequently, increase costs.

Evolution in Time (1980-2014) of Drought Based on Several Computation Indexes. Case Study of Banloc, Romania

Drought is a major issue that humanity confronts with and due to its vast ramifications, it is also most difficult to solve. Being a natural phenomenon, it has various manifestations which scalars have categorized into meteorological, agricultural, hydrological, environmental and others, in order to better define and understand this phenomenon. Several drought indices have been proposed by different scholars for measuring it which take rainfall, temperature, sun shining and other features into account. This of course, led to a variety of interpretations which makes the phenomenon even more difficult to size up and quantify its devastating effects on a longterm scale. The seven indexes this paper makes use of, for calculating drought are: N. Topor index, De Martonne index, Domuta hydroheliothermal index, Selianinov hydrothermal index, Palfai drought index and Lang rain index. In this paper, the case study conducted for Banloc in the 1980-2014 period reveals alternating wet and dry periods which do not pose any threat of aridization or desertification soon. However, a constant monitoring is imposed for these phenomena not to occur, made by the authorized law enforcement together with specialists from various fields.

Comparison of the climate indices based on the relationship between yield loss of rain-fed winter wheat and changes of climate indices using GEE model

Climate change is one of the most important meteorological phenomena that has had a lot of impacts on different sections with different spatial scales. In recent decades, climate changes affected by various factors especially human activities have had various impacts in different sections such as melting glaciers, various flood occurrence, occurrence of different droughts and etc. UNEP aridity Index (UNEP) and Modified De-Martonne index (MDM) are two more used indices to evaluate climate conditions in various regions of the world. In this paper; 1) the temporal trend of changes in climate conditions based on UNEP and MDM indices using climatological data (from 1967 to 2017) of 16 meteorological stations using parametric and non-parametric statistical tests were evaluated 2) the accuracy of UNEP and MDM indices were compared to assess climate conditions, based on the correlation between mentioned indices and percent of annual yield loss (AYL) in rain-fed winter wheat using simple and multiple Generalizes Estimation Equation (GEE) methods (for help managers to select more suitable and more accurate index to assess climate condition). Results showed, based on UNEP and MDM indices, climate indices in 93.75% and 87.5% of stations had a decreasing trend, but decreasing trend only in 56.25% and 50% of stations were significant at 5% level (respectively). The evaluation of the accuracy of UNEP and MDM indices showed that, in all stations, |B| coefficients between calculated AYL and UNEP and MDM indices and R2 coefficients between simulated AYL using AquaCrop model and predicted AYL using simple and multiple GEE methods in UNEP aridity index were more than MDM index. So, it is recommended to use UNEP aridity index to assess the climate conditions in different regions.

Trend assessment of climate changes in Iran

In this paper, according to the data of 40 stations in Iran during 1967-2014, the trend of climate changes and its severity are evaluated. A consistent correlation is highlighted for trends of De Martonne index as indicator of climate change and temperature rise in some stations. Based on the results of the temperature analysis, 70% of the country has become warmer, 3% has become colder and 27% has faced without significant changes. The precipitation in the 30.5% of the country has been decreased and 69.5% of the country didn’t show any significant changes. About the climate changes derived from climate index: 38.6 % of the area of the country has become drier and 61.4% of the area didn’t show any significant changes. A hazard classification for climate change was used showing 21% of the country under without or no change class, 22% under moderate class, 37.2% under severe class and 19.5% under very severe class. These results correspond to more desertification, frequency and intensity of droughts and observing lost lakes during the last decades in the study area.

Using present and past climosequences to estimate soil organic carbon and related physical quality indicators under future climatic conditions

This research aimed at testing the use of present and past climosequences to estimate soil organic carbon (SOC) and related physical quality indicators under future climatic conditions. The influence of climate on soil features was studied for four combinations of typical Mediterranean soil types and cropping systems, placed along climosequences of the past (P1: 1961–1990), present (P2: 1981–2010) and future (P3: 2021–2050). The four test areas were located in Italy, each one characterized by the same soil typology and cropping system, placed on similar morphological position and parent material, wide enough to cross climatic boundaries. Legacy soil profiles that were sampled in the P1 time-period were re-sampled in 2010–2011, to check for possible variations in soil characteristics. Besides SOC content and stock (Cstock), we examined some physical quality indicators for which the existence of relations with SOC is well-known, namely soil compaction and soil crusting susceptibility, soil erodibility, and soil loss by water erosion.Among several climatic indexes, the de Martonne index (IDM) resulted the most correlated with SOC. The IDM vs. SOC relationship was significant and not different in both P1 and P2 climosequences, highlighting the temporal stability of the relation between climate and SOC content. In the Vertisols of Sicily, cultivated under cereals, the P3 climosequence predicted a SOC reduction of more than 11%. This will lead to an increase of soil erodibility, susceptibility to compaction, and surface crust formation. On the contrary, in the Luvisols under forage crops of the Po Plain, a substantial Cstock increase (28.8%) is expected, with a consequent improvement in soil physical indicators. For the Luvisols under meadows of Sardinia, an increase in erosion of 13.5% is expected, because of increased precipitation volume (7.4%) and aggressiveness. In the Andosols under olive trees of Campania there is a predicted reduction in the Cstock (−6.3%) and an associated increase in soil loss (4.6%), while no marked variation is expected for the other soil physical indicators.We can conclude that climosequences are a useful tool to predict the future dynamics of some soil physical characteristics affected by climate change. Cstock and soil loss by water erosion are expected to change significantly under future climatic conditions, while minor changes are observed for erodibility, compaction and crusting susceptibility, even when SOC variations are significant. In the climosequences, the considered soil physical quality indicators resulted proportionally more affected by the cropping system than by the climate and, within the same cropping system, more variable according to the climate than the time. This outcome confirms the fundamental role of soil physics in controlling the resilience of the soil system to climate change.

The assessment of aridity in Leskovac basin, Serbia (1981-2010)

In the paper, the aridity is defined on the basis of four climate indices: De Martonne's index of aridity, Lang’s Rain Factor and Gracanin’s Rain factor for the vegetation period and hydrothermal coefficient of Seljaninov. While the annual value of the drought index (IDM) shows humid characteristics, the monthly values show the variability of the conditions. The summer months (July and August) are classified as semi-arid months, while the winter months (December–February) are extremely humid. The spatial distribution of the isoarids indicates that the northern part of the basin has the characteristics of a semiarid climate, while the southeastern parts are more humid. The analysis of mean annual values of the drought index indicates in semiarid conditions (1990 and 2000), but also the humid conditions (2005 and 2009). A positive linear trend indicates that there is a tendency towards humid conditions. The significance test confirms the existence of a statistically significant trend. During the vegetation period, semi-arid conditions are present (July–August). April is slightly humid, and October is moderately arid. The Lang’s Rain Factor (KFg) characterizes basin climate as semiarid, while the Gracanin rain factor for the vegetation period (KFm) indicates a moisture deficit in the summer months. Hydrothermal coefficient Seljaninova (HTC) indicates a lack of moisture in July and August. Vegetation period is characterized as insufficiently humid. Irrigation is one of the most important measures for solving drought problems, since the yield varies from year to year.

Evaluation of the hydroclimatic extremes in the upper Hron River basin, Slovakia

This paper deals with the occurrence of hydroclimatic extremes in the upper Hron River basin in Slovakia in 1951/61–2010. Select trends in hydroclimatic parameters in 1931/61–2010 are also studied. Emphasis is placed on the occurrence, frequency, and seasonality of dry episodes and flood events. The de Martonne index, the relative precipitation index, base flow index, low flow index, linear regression, the Mann-Kendall test and IHA software were used in the analyses. Mann-Kendall test pointed to significant changes in runoff of the upper Hron River basin. The annual runoff has decreased. Changes in minimums and maximums have had a fundamental influence on this decrease, particularly in the cold half year. Major changes occurred in Q1, QMax, Q75pct and 1-day, 3-day and 7-day maximum values. Approximately since the 1980s there has been a decrease in discharge events equal to or greater than one-year flood Q1. Events where discharges were equal or greater than Q5 occurred only in the first period 1951–1980 (in 1954 and 1974). The de Martonne index, the relative precipitation index and the low flow index show similar results, the longest aboveaverage period of annual values reached from 2007 to 2010 and the longest below-average period from 1990 to 1993.

Recent changes in continentality and aridity conditions over the Middle East and North Africa region, and their association with circulation patterns

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 69:25-43 (2016) - DOI: https://doi.org/10.3354/cr01389 Recent changes in continentality and aridity conditions over the Middle East and North Africa region, and their association with circulation patterns Ahmed M. El Kenawy1,2,*, Matthew F. McCabe1, Sergio M. Vicente-Serrano3, Sayed M. Robaa4, Juan I. Lopez-Moreno3 1Water Desalination and Reuse Center, Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology 23955-6900, Saudi Arabia 2Department of Geography, Mansoura University, Mansoura 35516, Egypt 3Instituto Pirenaico de Ecología, Spanish National Research Council (IPE-CSIC), Zaragoza, 50059, Spain 4Department of Astronomy, Space Science and Meteorology, Faculty of Science, Cairo University 12613, Egypt *Corresponding author: kenawy@mans.edu.eg ABSTRACT: A long-term (1960-2013) assessment of the variability of continentality and aridity conditions over the Middle East and North Africa (MENA) region was undertaken. Monthly gridded temperature and precipitation data from the Climate Research Unit (CRU) (TS3.22 version) were used to compute the Johansson Continentality Index (JCI) and the Marsz Oceanity Index (MOI). In addition, the De Martonne index and the Pinna index were employed to assess recent changes in aridity conditions. All indices revealed a statistically significant increase in continental influences over the region, particularly in the Nile Basin and the Fertile Crescent. For aridity, the results suggested a generally statistically insignificant increase, with the most rapid changes occurring over the most humid regions (i.e. the Ethiopian Highlands and the Fertile Crescent). In order to explain the observed changes in the continentality and aridity conditions, we assessed the relationship between aridity and continentality indices and a wide range of large-scale circulation patterns. Results indicate that the spatial variability of continentality (as well as aridity) was closely coupled with the Atlantic modes of variability, e.g. the Eastern Atlantic pattern and the Atlantic Meridional Mode, compared to those of the Mediterranean Sea and the Indian Ocean. The results of this work highlight change processes in 2 important climate features in one of the hottest regions on Earth. Improving our understanding of the spatio-temporal characteristics of climate continentality and aridity has implications for a diversity of socio-political, economic, hydrological, and ecological activities in the MENA region. KEY WORDS: Continentality · Aridity · Precipitation · Temperature · Circulation patterns · Middle East and North Africa · MENA Full text in pdf format PreviousNextCite this article as: El Kenawy AM, McCabe MF, Vicente-Serrano SM, Robaa SM, Lopez-Moreno JI (2016) Recent changes in continentality and aridity conditions over the Middle East and North Africa region, and their association with circulation patterns. Clim Res 69:25-43. https://doi.org/10.3354/cr01389 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 69, No. 1. Online publication date: May 30, 2016 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2016 Inter-Research.

Relación clima-vegetación: adaptaciones de la comunidad del jarillal al clima semiárido, Parque Nacional Lihué Calel, provincia de La Pampa, Argentina

The study of vegetation from the Geography perspective focuses on the analysis of the spatial distribution and on the factors affecting it. One of these factors is the climate, which determines the characteristics of the vegetation and, on a larger scale, of the communities. The aim of this paper is to analyze the climate-vegetation relationship by studying adaptations of the jarillal community regarding the semiarid climate in the Lihué Calel National Park, Argentina.Therefore, this contribution is concerned with the knowledge of the characteristics of the environment in order to understand how vegetation responds to certain phenomena, so management of protected areas will be more suitable. Lihué Calel National Park is a national protected area located in the south-center of La Pampa province, Argentina. According to Cabrera (1976) the area belongs to the floristic province of “monte” and the climate is warm and dry.In the interest to achieve the goals of this paper, Thornthwaite and Mather's water balance was done. The data was collected from a weather station that belongs to the national park, for the period 1995-2010. Emberger's pluviothermic coefficient, Lang's rainfall index, De Martonne's aridity index and Currey's continentality index were analyzed. In addition, ten stands or plots of vegetation were placed to determine the floristic composition and the vegetation physiognomy. Then, plants species were identified as individuals and their adaptive responses were also analyzed. In conclusion, the survey verified that semi-arid climate conditions determine the morphology and the appearance of jarillal.Climate analysis shows that for the period 1995-2010 the average annual temperature is 16.2° C and reveals that thermal summers and winters are well differentiated. Large water deficit is defined, because water balance indicates that the evapotranspiration exceeds precipitation during every month of the year. According to Thornthwaite's criteria, the area is a semiarid climate type. With the analysis of other bioclimatic indices, more information is obtained: Lang's index value is 25.7 (arid), Emberger's index is 41.8 (semiarid), De Martonne's index is 15.9 (that refers to a semi-arid climate) and, at last, Currey's index certified the existence of a continental climate because the result was 1.16.Vegetation was surveyed and the result was quite interesting: 1 508 individuals that belong to 33 species. The percentage is: shrubs 57.6%, grasses 36.4% and Trees 6.1%. Most of them were evergreen and only some deciduous. The distribution of vegetation in Lihué Calel responds to the semi-arid conditions. Some adaptations were observed like the development of the deep root system with an horizontal pattern in order to absorb the water from the soil, the loss of leafs in the unfavorable season, the replacement of leaves by thorns, small resinous leaves, leaf tilting and extensive roots, among others.The dominant plant of the jarillal is Larrea divaricata and it is considered as a xerofite plant. The process indicates that when stomata are open, transpiration rates increase; when they are closed, transpiration rates decrease. The Cactaceae family is represented by two species: Opuntia puelchana and Cereus aethiop. They are considered succulent plants that keep humidity inside. During rainy periods they absorb large amounts of water that they then use during the dry periods.These types of studies are relevant to understand how plants adapt to different environmental events, whether they are natural and/or anthropogenic. As a reference, in 2003, major fires occurred inside the National Park and they affected 7 000 hectares. The resinous leaves of the jarilla helped to propagate the fire all around the place. The next phase of the investigation process will be related to the physiological and morphological properties, through chemical analysis, so the adaptation of vegetation can be tested. With these new studies, the final purpose will be reached: good practice for plant conservation.

Análisis de la sequía y desertificación mediante índices de aridez y estimación de la brecha hídrica en Baja California Sur, noroeste de México

In Baja California Sur (bcs), Mexico, dry-semi warm and warm climates prevail associated to an extreme trend of diurnal temperatures and the environmental dryness. In this State, the maximum summer t exceeds 40° C and the minimum varies from 5 to 12° C, with a minimal for the State of 2° C in winter, at the top of the Sierra de La Laguna; only Los Cabos region has a warm humid climate. Because precipitation in the state is low, oscillating from 310 mm in the southern area of the state to 120 mm per year in the northern portion, predictions and scenarios under climate conditions point to an intensification of droughts. The aim of this work was to carry out a comparative analysis of trends of temperature, precipitation and hydro-environmental aridity among contrasting localities of bcs, by means of the application of Aridity Indexes and the determination of the Standardized Water Gap (bhe), through a numerical scale modification of the De Martonne Index. With the values of temperature and precipitation for the different climate change scenarios for four weather stations, the indicators Hydro Environmental Availability Index (idha) and Hydro Environmental Drought Index (isha) were calculated to determine their trend and the consequent bhe, an innovative quantification of water deficit, which is proposed in this paper. The maximum value of bhe (10 units), indicating prevalence of drought, is observed from February to June in almost the entire state. Results suggest that bhe tend to increase and intensify under climate change conditions, which is more evident from the South towards the North of the State. According to the trends of the indexes idha, isha and bhe, under six scenarios of climatic change for four regions of bcs, bhe can be estimated with a major significance for the region Gustavo Díaz Ordaz-Vizcaíno, Mulegé County, in the North of the State, where may reach a value bhemax = 10 and bhemin = 7.23, values which suggest extreme dryness, corresponding to the maximum values among localities. We conclude that the analysis of trends in PP and t and their integration into bi-parametric indicators are a reliable tool for the construction of scenarios and climate change trends.

Aridity Variability in the Last Five Decades in the Dobrogea Region, Romania

The present study constitutes a climatic approach of aridity trend analysis in the south-eastern part of Romania (Dobrogea region), over the past five decades. The analysis is based on a series of investigations on the temporal trends of certain climatic parameters that play a key role in a territory's climatic variability, such as temperature, precipitation, and potential evapotranspiration. In this respect, a series of aridity index trends (De Martonne Index, UNEP Index, and Water Deficit Index), recorded between 1961 and 2009, was analyzed, using climatic parameters provided by eight weather stations in the Dobrogea region. While the results showed that the last five decades were generally characterized by an upward climatic aridity trend (increasing temperatures and potential evapotranspiration in all considered instances), there are certain regional differences due to precipitation regime variations (higher rainfall values were recorded at four weather stations). In terms of maximum aridity conditions, the study reveals that the most critical aridity index values were reported in 1990, 2000, 2001, 2003, and 2008, especially at the weather stations located in the northern part of the Dobrogea region. The situation is slightly different in the central-southern part, where the results indicated an aridity trend decline coupled with an increase of annual precipitation amounts, especially between 1995 and 2009.

A survey of temperature and precipitation based aridity indices in Iran

In arid and semi-arid lands with warm climates, aridity and associated water scarcity is more severe because of greater populations and associated water use. The goal of this study was to explore the spatial and temporal variations of the de Martonne and Pinna aridity indices over Iran based on temperature and precipitation data from 41 stations for 40 years (1966–2005). The spatially interpolated maps of the aridity indices were prepared using the Ordinary Kriging technique in a GIS environment. The arid and semi-arid regions cover about 88% of Iran according to the de Martonne index, while about 96% of the country's areas are classified as dry and semi-dry based on the Pinna index. A strong relationship was found between the values of the de Martonne and Pinna indices, confirming their similar spatial distribution. Around 63% of the two indices series had a decreasing tendency. The significant decreasing trends of the aridity indices were observed mainly in the western and northwestern regions of the country. The relative changes of the aridity indices at the stations with significant decreasing trends were in the range of 18%–54%.

Changes in the forest ecosystems in areas impacted by aridization in south-western Romania.

BackgroundIn the past few decades, global climate change has accentuated the intensification of aridization in South-Western Romania, with direct and indirect consequences on the quality of forest ecosystems. In addition to qualitative deterioration, the quantitative changes brought about by intensive anthropic deforestation have created the conditions for a decline in the size of forest areas on vast tracts of land. The paper aims to analyze the qualitative and quantitative changes in the forest ecosystems in South-Western Romania, changes due to the synergic context of the global climate changes and the anthropic pressures of the past three decades. In order to capture the evolution of aridization in the study area, specific aridization indexes have been calculated, such as the De Martonne index and the UNEP aridity index. 1990 and 2011 satellite images have been used in order to quantify the qualitative changes.ResultsThe results obtained indicated that, in the past two decades, the quality of the biomass declined as a result of the increase in the climatic aridity conditions (De Martonne si UNEP aridity index, indicating in the last decades, annual values under 15 mm/°C, and under 0.5 mm/mm, that means that the values situated under these thresholds, describe arid and semi-arid climate conditions). Also, the uncontrolled logging across vast surfaces caused the loss of forest ecosystems by 7% in the overall study area, during the last three decades.ConclusionsThe severe effects of aridization meant, first of all, a significant decline in the quality of the ecosystem services supplied by forests. In the absence of viable actions to correct the present situation, the extremely undesirable consequences of an ecological and social nature will arise in the near future.

Soil degradation, landscape and climate variations in a Mediterranean agro-forest system (Thriasio, Greece): proposal for a desertification indicator using time series analysis

As a contribution to soil degradation and desertification monitoring in the northern Mediterranean basin, the present study investigates long-term climate variations in the traditional agro-forest system of Thriasio Plain (Greece) by examining month average temperature, precipitation, relative humidity, Standardised Precipitation Index (SPI) and de Martonne index time series between 1958 and 2011. In the last twenty years, the area experienced an increased anthropogenic pressure due to urbanisation and industrialisation processes. Results indicate a moderate trend towards a warmer and drier climate with a slight increase in the range of the observed values for precipitation and temperature. Relative humidity decrease by 0.1% per year at both year and month base. Results point out the complexity of climate variations at the local scale and the importance of air humidity trends depending on rainfall and temperature regimes in the Mediterranean basin.

Evolution of meteorological drought characteristics in Vietnam during the 1961–2007 period

The drought conditions over the seven sub-climatological regions in Vietnam are examined using three meteorological drought indices: de Martonne J, PED, and Standardized Precipitation Index (SPI). According to the seasonal probabilities of drought occurrence estimated by the de Martonne index, droughts mainly occur between November and March in all the sub-regions. The PED index and the SPI index generally show high probabilities of drought occurrence from April to August and from May to October, respectively. In the southern sub-regions of Vietnam, droughts more frequently occur in El Nino years and wet conditions are more frequently observed in La Nina years. However, such El Nino–Southern Oscillation influences are not clearly observed in the northern sub-regions. During 1961–2007, droughts significantly increased in the northern part of Vietnam. In the southern regions, PED shows increasing drought conditions while J and SPI show decreasing drought trends for almost all the stations.

The impact of the drought on the main crops cultivated in Northeastern Bulgaria

Drought is one of the consequences of a reduction of rainfall over a long period of time. Often a number of meteorological elements as high temperatures, strong winds and low relative humidity occurs in conjunction with the drought. These facts make drought very strongly expressed. The present paper aims to analyze the intensity and the seasonal differences of meteorological drought in Northeastern Bulgaria and to characterize the drought impact on the main crops cultivated in the study area. The tendencies of the seasonal and the annual air temperatures and precipitation are investigated. Drought periods are revealed on the base of precipitation anomalies and the drought indices as Standartized Precipitation Index (SPI) and De Martonne Index. The driest years for the period 1961 – 2011 have been established. The production of the main crops in the study area is analyzed on the background of climate change. The information from climate models is used in order to describe future climate and to make the recommendations for crop cultivation in relation to climate impact.

Aridity in Vojvodina, Serbia

For investigating aridity in Vojvodina, two parameters were used: the De Martonne aridity index and the Pinna combinative index. These indices were chosen as the most suitable for the analysis of climate in Vojvodina (a region in northern part of Serbia). Also, these indices were calculated from data obtained from 10 meteorological stations for the period from 1949 to 2006. The spatial distribution of the annual and seasonal De Martonne and the Pinna combinative indices as well as the mean monthly values of the De Martonne index and aridity trends of these indices are presented. There were two, four, and five types of climate on a yearly, seasonal, and monthly basis in Vojvodina, according to the De Martonne climate classification which consists of a total of seven types. In addition, semi-humid and humid climate types were represented in the region, on a yearly basis. The winter season was dominated by wetter types of climate, while the summer season was characterized by drier ones. During the spring and autumn seasons, there were types of climate which range between both aforementioned types. Two out of three climate types, which can be identified using the Pinna combinative index, were registered in Vojvodina region. The most dominant climate type was the semidry Mediterranean with formal Mediterranean vegetation, while the humid type was only identified in one small part of southwestern Vojvodina. The calculated values of both aridity indices showed that there were no annual trends. Therefore, it can be considered that there were no recent aridity changes during the observed period. For paleoclimate, the general story is more complex. The lack of aridity trends in the recent period from 1949 to 2006 supports the fact that Vojvodina has very well preserved loess–palaeosol sequences from the Middle and Late Pleistocene, which indicates that crucial point for their preservation was caused by the weak aridity variability in the region.

Déterminisme climatique des années de croissance extrême chez le chêne sessile dans la moitié nord de la France

The growth response of sessile oak to extreme climatic years has been investigated from 1914 to 1993 using extreme years growth, i.e. pointer years. 31 mature and pure stands were cored in northern France (720 trees), under varied climates, from oceanic to semi-continental conditions. The analysis has highlighted similarities in growth characteristics throughout the study area : abrupt growth changes depend mainly on summer temperatures and precipitations (from May to July), narrow rings generally correlate with warm and dry climate (1921, 1976, 1989). Narrow rings also occur with strong winter frosts (1956). Pointer years analysis has allowed to define 2 main regions in northern France, with specific responses to extreme climatic events : plots in north-western France (from Brittany to Champagne) under oceanic climate, with a decennial pointer years frequency around 0,2 strongly correlated with summer De Martonne Index, and plots in north-east France (Lorraine, Alsace, Franche-Comté) under semi-continental climate, with higher frequency (around 0,3), depending on both summer and winter conditions.

Basal metabolism is correlated with habitat productivity among populations of degus ( Octodon degus)

Several competing hypotheses attempt to explain how environmental conditions affect mass-independent basal metabolic rate (BMR) in mammals. One of the most inclusive is the hypothesis that associates BMR with food habits, including habitat productivity. The effects of food habits have been widely investigated at the interspecific level, and variation between individuals and populations has been largely ignored. Intraspecific analysis of physiological traits has the potential to compensate for many pitfalls associated with interspecific analyses and serve as a useful approach for evaluating hypotheses regarding metabolic adaptation. Here we tested the effects of climatic variables (mean annual rainfall = PP, mean annual temperature = T A), net primary productivity (NPP) and the de Martonne index (DMi) of aridity on mass-independent BMR among four populations of the caviomorph rodent Octodon degus along a geographic gradient in Chile. BMR was measured on animals maintained in a common garden acclimation set-up, thus kept under the same environment and diet quality for at least 6 months. Mass-independent BMR was significantly different among degu populations showing a large intraspecific spread in metabolic rates. A very large fraction of interpopulational variability in mass-independent BMR was explained by NPP, PP and DMi. Our results were conclusive about the effects of habitat productivity on setting the level of mass-independent BMR at the intraspecific–interpopulational level.