Search Results (24)

Aridity represents a fundamental climatic constraint governing water resources, ecosystem functioning, and agricultural systems in transitional climate zones. This study examines the spatial organization and temporal variability of aridity and thermal continentality in North Macedonia using observational records from 13 meteorological stations distributed across contrasting altitudinal and physiographic settings. The analysis is based on homogenized monthly and annual air temperature and precipitation series covering the period 1991–2020. Aridity and continentality were quantified using the Johansson Continentality Index (JCI), the De Martonne Aridity Index (I_DM), and the Pinna Combinative Index (I_P). Temporal consistency and trend behavior were evaluated using Pettitt’s nonparametric change-point test, linear regression, the Mann–Kendall test, and Sen’s slope estimator. Links between aridity variability and large-scale atmospheric circulation were examined using correlations with the North Atlantic Oscillation (NAO) and the Southern Oscillation Index (SOI). The results show a spatially consistent and statistically significant increase in mean annual air temperature, with a common change point around 2006, while precipitation displays strong spatial variability and limited temporal coherence. Aridity patterns display a strong altitudinal control, with extremely humid to very humid conditions prevailing in mountainous western regions and semi-humid to semi-dry conditions dominating lowland and southeastern areas, particularly during summer. Trend analyses do not reveal statistically significant long-term changes in aridity or continentality over the study period, although low-elevation stations exhibit weak drying tendencies. A moderate positive association between I_DM and I_P (r = 0.66) confirms internal consistency among aridity indices, while summer aridity shows a statistically significant relationship with the NAO. These results provide a robust climatic reference for North Macedonia, establishing a first climatological baseline of aridity conditions based on multiple indices applied to homogenized observations, and contributing to regional assessments of hydroclimatic variability relevant to climate adaptation planning. Full article

This study presents an integrated analysis of climate-driven phenology and infestation dynamics of the invasive oak lace bug (Corythucha arcuata) in foothill oak ecosystems of Rășinari, Romania. Using reconstructed microclimatic data for 2024–2025, systematic field monitoring, degree-day (GDD) modeling, and the De Martonne aridity index, we assessed the combined effects of thermal accumulation and hydric stress on multigenerational development. Results indicate that warm springs and sustained summer temperatures enabled the completion of two full generations (G₁–G₂) in both years, while recurrent late-summer aridity intensified foliar vulnerability and accelerated nymphal development. A third generation (G₃) was initiated but remained incomplete due to declining autumn temperatures and photoperiod constraints. Strong habitat-specific differences were observed: exposed forest-edge stands exhibited the highest damage levels (up to 90%), whereas closed-canopy stands benefited from microclimatic buffering. The combined GDD–aridity framework showed close agreement with observed phenological transitions, providing a robust tool for identifying high-risk infestation periods. Climatic projections for 2026 suggest further advancement of generational timing under continued warming and increasing aridity. These findings highlight the growing climatic suitability of foothill oak ecosystems for C. arcuata and support the development of early-warning systems and adaptive strategies for sustainable oak forest management. Full article

Mixed stands enhance climate resilience and ecosystem service provision through functional diversity, but their productivity depends on intra- and interspecific competition, forest structure, stand density, and site conditions. In this study, we analyzed the effects of competition and aridity on the growth of European beech (Fagus sylvatica L.) in mixed and pure stands, using data from 38 plots of the Italian National Forest Inventory (NFI, 2015). To understand the variables influencing European beech growth, tree-level basal area increment models were applied, incorporating different competition structures (intraspecific, interspecific, size-symmetric, and size-asymmetric) and aridity index (De Martonne). Results showed that size-asymmetric intraspecific competition negatively affected European beech growth, highlighting low self-tolerance, especially in pure stands where growth was lower than in mixed stands. In mixed stands, European beech growth was shaped by size-dependent competition and the relative dominance of coexisting species, benefiting from size-asymmetric and hindered by size-symmetric interactions. Additionally, European beech growth was shaped by aridity and stand structure (Gini coefficient and density), with drought sensitivity mitigated in mixed stands and enhanced growth in structurally diverse, low-density stands. This study highlights how species interactions, aridity, and stand structure jointly shape tree growth, underscoring their importance for climate-adaptive forest management. Full article

Viticulture in the Iberian Peninsula is increasingly threatened by climate change, particularly rising temperatures and prolonged droughts. This study evaluates the ability of the De Martonne Index (DMI), a simple climatic aridity index based solely on temperature and precipitation, to serve as a proxy for vineyard health over a 30-year period (1993–2022). Vineyard health was assessed using the Vegetation Health Index (VHI), derived from satellite remote sensing data. DMI values were computed from bias-corrected ERA5-Land data, and VHI composites were generated from NOAA satellite imagery. Vineyard-specific outputs were isolated using land cover datasets, and a contingency analysis compared drought classifications from both indices. Results show a strong spatio-temporal correspondence between low DMI values and reduced VHI, with agreement rates for severe/extreme drought conditions reaching up to 56% under the most restrictive DMI thresholds. In the analyzed period, years such as 1995, 1997, 2005, 2009, and 2012, showed over 20% of vineyard areas affected by moderate-to-severe/extreme drought. The spatial analysis revealed that northern and northwestern regions of the peninsula experienced less drought stress, while central and southern areas were more frequently affected. This approach demonstrates that the DMI alone can provide a reliable assessment of vineyard health, potentially enabling its direct use with seasonal forecasts, which are generally available for temperature and precipitation, to anticipate drought impacts and support adaptation in viticulture. The proposed methodology is scalable and transferable to other crops and regions, serving as a tool for climate adaptation strategies in viticulture. Full article

Understanding long-term precipitation variability is essential for assessing the climate’s impact on sensitive ecosystems, particularly in regions of high environmental value, such as the Danube Delta Biosphere Reserve (DDBR). This study examines the temporal dynamics of monthly precipitation in the Danube Delta, Romania, spanning the period from 1965 to 2019. Three approaches were used to analyze climatic variability: Change Point detection (CPD) to identify shifts in precipitation regimes, the De Martonne Index (I_M) to assess aridity trends, and the Standardized Precipitation Index (SPI) to evaluate drought conditions across annual and monthly scales. Using robust monthly precipitation and temperature datasets from the Sulina meteorological station, CPD analysis revealed statistically significant structural breaks in precipitation trends, suggesting periods of altered climate behavior likely associated with broader regional or global climate changes. I_M values indicated mostly hyper-aridity and aridity at monthly and annual scales, respectively. No monotonic trend was found in this index during the analyzed segments, as emphasized by the Mann–Kendall (MK) test. SPI values provided further evidence of variability in the precipitation regime, highlighting a transition toward more extreme hydrological conditions in the region. The combined use of these indices offers a comprehensive view of the evolution of climatic conditions in the Danube Delta. The findings underscore the growing vulnerability of this unique wetland ecosystem to climatic variability, supporting the need for adaptive water management strategies in the face of anticipated future changes. Full article

Rostov Oblast is one of the key grain-producing regions in Russia, accounting for 6% of the total grain production. However, it faces an increasing risk of climate aridization, which requires an accurate scientific assessment to ensure the food security of the country. The present study analyzes the spatial and temporal dynamics of climate aridification in the Rostov region for the period 1951–2054. This analysis is based on ERA5 reanalysis data and CMIP6 forecast models (MPI-ESM1-2-HR, CanESM5, BCC-CSM2-MR). The analysis indicates that the annual mean temperature in the region has increased by 2–3 °C since the 1950s, reaching 12 °C in 2023. At the same time, precipitation shows significant interannual variability with no detectable long-term trend. Spatial analysis reveals a stable meridional temperature gradient and zonality of precipitation distribution. The southeastern parts of the region are characterized by the highest degree of aridification. Projection models indicate further warming (+1.5–3 °C by 2054) and increasing contrasts between western (wetter) and eastern (drier) areas. Projections derived from the CMIP6 models indicate an intensification of aridification, accompanied by a decrease in the De Martonne index of 15–25% by the year 2054. The area of territories with arid climates is expected to increase from 30% to 40%. The most vulnerable regions will be in the southeast part of Rostov Oblast, where the De Martonne index values are predicted to decrease to less than 10. The potential increase in temperature and evapotranspiration, coupled with spatial differentiation, could pose significant risks to the sustainability of the agro-industrial complex, particularly in the southeastern part of the region. Full article

Based on long-term observations of the water discharge (WD) from 1878 to 2018, the main trends and patterns of its change in the basin of one of the largest rivers in the east of the East European Plain, the Vyatka River, were revealed using a set of standard statistical procedures and a graphical analysis of the WD probability curves. Three main phases of the annual river WD were identified, corresponding to the periods 1878–1929, 1930–1977, and 1978–2018. The first and third periods were characterized by increased WD (by 22–23%) relative to the medium period, and the differences in the average annual WD characteristics between these periods were statistically significant. It is also noteworthy that the difference in the average annual WD between the first and last periods of increased WD was very small and statistically insignificant. A gradual increase in the share of the so-called normal annual WD and a decrease in the abnormal (including extreme) annual WD were noted from 1878–1929 to 1978–2018 in the predominantly northern half of the river basin. At the same time, in the predominantly southern half of the basin, according to the analysis of only the periods 1930–1977 and 1978–2018, the so-called normal and abnormal WD remained almost unchanged; only a slight increase in positive anomalies of the WD was noted. Increased intra-annual variability in the WD was characteristic of the period of its reduced average annual value. Between the three identified periods, a gradual reduction in the water runoff coefficient was observed during the warm (mainly summer) season in the Vyatka River basin. The specified long-term variability in the water discharge of the Vyatka River was chiefly due to long-term changes in climatic factors, primarily the ratio of the air temperature and precipitation, expressed as the De Martonne aridity index. The duration of the principal cycle of these changes was 82 years. An additional contribution could also have been made by the widespread reduction in cropland in the study region in recent decades. The obtained results can be preliminarily considered representative of the entire southern sector of the boreal forest zone (taiga zone) of the east of the East European Plain. Full article

Environmental conditions can control the structure and composition of plant communities by changing the direction and intensity of plant–plant interactions. In extreme arid regions, accompanied by water and soil nutrient limitation, positive shrub–herb interactions may vary along an aridity gradient, leading to changes in the ecological consequences of shrub encroachment. We investigated the vegetation and soil within 60 shrub patches and their paired interspaces at 20 sites from the northeast to southwest desert steppe of Inner Mongolia, China, encroached by the Caragana microphylla shrub. The results show that aridity, soil organic matter (SOM), and soil total phosphorus (TP) were the main factors driving shrub–herb interactions. The positive shrub–herb interaction first increased and then decreased with increasing aridity (in the range of De Martonne Index (DMI) 0.54 to 1.85). The DMI indirectly affected shrub–herb interaction through TP, and the facilitation of shrubs on herbs coverage and biomass increased with the increase in TP. The SOM can directly affect the shrub–herbs interaction, and the facilitation of shrubs on herb diversity decreases with the increase in SOM. Our results indicate that the shrub–herb interaction changes along the environmental stress gradient; in general, shrubs have a positive effect on herbaceous communities along the aridity gradient. This study underscores the positive effects of shrubs on vegetation restoration in desert steppes, and changing environmental conditions by increasing precipitation, increasing TP content, and reducing SOM content can enhance the facilitation of shrub on herbs to accelerate the ecological restoration of degraded desert steppe. Full article

Drought poses a significant risk in many parts of the world, especially in regions reliant on agriculture. Evaluating this risk is an essential step in preventing and reducing its impact. In this context, we assess the drought intensity at six sites in Constanța County (Romania) using the de Martonne aridity index. The risk of aridity and vulnerability to drought were evaluated by the Drought Hazard Index (DHI) and Drought Risk Index (DRI), computed based on the Standardized Precipitation Index (SPI). The de Martonne index indicates a variation between the slightly arid and semi-arid climates for Adamclisi station, with periodic changes from semi-arid to arid. At Cernavodă station, we notice a passage from an arid period towards a moderately humid one (in 2005), followed by a movement in the opposite direction to the limit of the arid zone (in 2011), and a return inside the “limits” of the semi-arid to moderately arid climate. A similar variation for 2000–2018 is noticed at Medgidia, Hârșova, and Mangalia. DRI classifies two stations in the low risk to drought category and one in the moderate risk to drought class. The other two locations experience a high or very high risk of drought. The drought intensities varied in the intervals 0.503–1.109 at Constanța, 0.473–1.363 at Mangalia, 0.511–1.493 at Adamclisi, 0.438–1.602 at Hârșova, 0.307–1.687 at Medgidia, and 0.463–1.307 at Cernavodă, and the prolonged drought periods were over 99 months at all stations. Full article

Drought is a major problem in the world and has become more severe in recent decades, especially in arid and semi-arid regions. In this study, a Google Earth Engine (GEE) app has been implemented to monitor spatiotemporal drought conditions over different climatic regions. The app allows every user to perform analysis over a region and for a period of their choice, benefiting from the huge GEE dataset of free and open data as well as from its fast cloud-based computation. The app implements the scaled drought condition index (SDCI), which is a combination of three indices: the vegetation condition index (VCI), temperature condition index (TCI), and precipitation condition index (PCI), derived or calculated from satellite imagery data through the Google Earth Engine platform. The De Martonne climate classification index has been used to derive the climate region; within each region the indices have been computed separately. The test case area is over Iran, which shows a territory with high climate variability, where drought has been explored for a period of 11 years (from 2010 to 2021) allowing us to cover a reasonable time series with the data available in the Google Earth Engine. The developed tool allowed the singling-out of drought events over each climate, offering both the spatial and temporal representation of the phenomenon and confirming results found in local and global reports. Full article

Aridity conditions in semi-arid lands with warm climates are key variables that must be assessed to properly manage water and plan to minimise the threat of desertification. This study analyses the spatial distribution of aridity in Extremadura, southwestern Spain, using the De Martonne aridity index (I_DM), considering a historical reference period (1971–2005) and three-time intervals: 2006–2035 (near future), 2036–2065 (mid-century) and 2066–2095 (end of the century). Projections were computed using a set of ten global climate model (GCM) and regional climate model (RCM) combinations under two representative concentration pathways (RCPs), RCP4.5, an intermediate anthropogenic radiative forcing scenario, and RCP8.5, a fossil-intensive emission scenario. Progressive strengthening of aridity conditions over Extremadura was evident until the end of the century, mainly under the RCP8.5 scenario. From the predominance of the Mediterranean aridity class in the south of the region during the reference period, semi-arid conditions will soon spread across this zone, occupying most of it during mid-century and later. In the north of Extremadura, less arid conditions will be reduced to the highest elevations, increasing the Mediterranean and semi-arid categories, particularly under the RCP8.5 scenario. Consequently, the projected increase in aridity conditions in Extremadura will make this region more vulnerable to climate change. Policies devoted to adapting to the expected conditions and controlling aridity in vulnerable areas will be necessary to mitigate the negative impacts, with significant environmental and socio-economic implications in the region. Full article

Aridity is a key determinant of agriculture worldwide due to rising temperatures, rainfall variability, and drought frequency and intensity, amongst other factors. The De Martonne aridity index is particularly useful to evaluate the spatial and temporal variations in aridity in agricultural regions for characterising the climate of these areas and evaluating their susceptibility to climate change. From the mean precipitation and maximum–minimum daily temperature values recorded at 108 weather stations over 32 years (1989–2020) in Extremadura (southwest Spain), spatial analysis of aridity was performed at different grapevine growth stages. The present study aimed to (1) determine the mean aridity conditions in Extremadura according to year and growth stage and (2) assess aridity in six grapevine-growing areas of Ribera del Guadiana de Extremadura (Spain) protected designation of origin (PDO). To visualise aridity patterns, maps were generated using a geographic information system and a multivariate regression geostatistical algorithm (ordinary kriging). The climate of Extremadura is primarily Mediterranean at the annual scale, and aridity widely varies from extremely humid at the dormancy stage to arid at the berry development and ripening stages. This variation shapes the conditions of the studied grapevine-growing region. Furthermore, large differences were noted amongst the sub-areas of the Rivera del Guadiana PDO at the initial and final grapevine growth stages, requiring differential crop management. In addition, analysis according to growth stage allowed us to identify the most vulnerable areas and periods to climate change and potential grapevine-growing areas highly suitable for this climate. Full article

The Mediterranean vegetation belt on the eastern Adriatic covers an area of nearly 15,000 km². It is comprised of forest stands that can be divided into three vegetation zones based on the presence of certain plant species within each: sub-Mediterranean, eu-Mediterranean, and steno-Mediterranean. The dominant ecological factors result in the domination of specific tree species within the floral composition between these vegetation zones. The aim of this study was to collect climate data from 38 weather stations over a 30-year period to compare climate data and bioclimate properties in the area of these three vegetation zones. The results confirmed statistically significant differences between the main climatic elements and most bioclimatic indices between the vegetation zones. Cooler and more humid conditions were found in the sub-Mediterranean zone, warmer and somewhat drier conditions in the eu-Mediterranean zone, and particularly pronounced warm and dry conditions in the steno-Mediterranean zone. However, the analysis of the main components for researching climate parameters showed that the mean annual air temperature, average minimum air temperature of the coldest month of the year and continentality index, length of the dry season, and de Martonne aridity index contribute the most to the grouping of vegetation in forest stands in the Mediterranean vegetation belt of the eastern Adriatic. Full article

The recent climate change scenarios show significant increases in temperature and extreme drought events in Southern and Eastern Europe by the end of the 21st century, which will have a serious impact on forest growth and adaptation, and important consequences for forest management. The system of provenance regions, according to the OECD Scheme and EU Directive, was thought to encourage the use of the local seed sources, under the concept ‘local is the best’. However, climate is changing faster than some species or populations can adapt or migrate, which raises some uncertainties with respect to the future performance of local populations. In Romania, as in other countries, the delimitation of provenance regions is based on geographical, ecological and vegetation criteria. The aim of this study is to evaluate: (1) the climate change that has occurred at the level of the provenance regions; (2) which regions will be most vulnerable to climate change; (3) which forest types will be the most vulnerable in a certain region; and (4) changes in the climatic envelope of forest species. Several climatic parameters and an ecoclimatic indices have been calculated and analyzed at the level of provenance regions, subregions and ecological sectors (forest types) in Romania, during the period 1951–2020. The results highlight a general shift towards warmer and drier conditions in the last 30 years, the mean annual temperature increasing with 0.3–1.1 °C across the provenance subregions. The De Martonne aridity index for the vegetation season shows that 86% of the ecological sectors fell into the arid and semiarid categories, which indicates a very high degree of vulnerability for forest species. On the Lang rainfall index, forest steppe climatic conditions occurred in all pure or mixed pedunculate oak forests, thermophile oak species, meadow forests, poplar and willow, Turkey oak and Hungarian oak forests. The Ellenberg coefficient highlights that the warming process is more evident along the altitude and the degree of vulnerability increase at lower altitude or at the edge of species distribution. The climate envelopes of many forest species have already shifted to another ecosystem’s climate. This paper presents the importance of re-delineation the provenance regions for the production and deployment of forest reproductive materials according to the climate change occurred in the last decades, as a fundamental tool for an adaptive forest management. Full article

Urbanization and climate change are two inevitable megatrends of this century. Knowledge about the growth responses of urban trees to climate is of utmost importance towards future management of green infrastructure with the aim of a sustainable provision of the environmental ecosystem services. Using tree-ring records, this study analyzed growth response to climate by stem diameter at breast height (DBH) of 1178 trees in seven large cities worldwide, including Aesculus hippocastanum L. in Munich; Platanus × hispanica Münchh. in Paris; Quercus nigra L. in Houston; Quercus robur L. in Cape Town; Robinia pseudoacacia L. in Santiago de Chile, Munich, and Würzburg; and Tilia cordata Mill. in Berlin, Munich, and Würzburg. Climate was characterized following the de Martonne aridity index (DMI). Overall, trees showed an 8.3% lower DBH under arid than humid climate at the age of 100. Drought-tolerant tree species were overall not affected by climate. However, R. pseudoacacia showed a lower diameter when growing in semi-dry than humid climate. In contrast, drought-sensitive tree species were negatively affected by arid climate. Moreover, the effect of drought years on annual diameter increment was assessed. P. × hispanica and R. pseudoacacia appeared as the most drought-resistant species. The highest sensitivity to drought was detected in T. cordata and Q. robur. A. hippocastanum and Q. nigra showed a lower diameter growth during drought events, followed by a fast recovery. This study’s findings may contribute to a better understanding of urban tree growth reactions to climate, aiming for sustainable planning and management of urban trees. Full article