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During the 2015–2016 El Niño, the Amazon basin released almost one gigaton of carbon (GtC) into the atmosphere due to extreme temperatures and drought. The link between the drought impact and recovery of the total carbon pools and its biogeochemical drivers is still unknown. With satellite-constrained net carbon exchange and its component fluxes including gross primary production and fire emissions, we show that the total carbon loss caused by the 2015–2016 El Niño had not recovered by the end of 2018. Forest ecosystems over the Northeastern (NE) Amazon suffered a cumulative total carbon loss of ∼0.6 GtC through December 2018, driven primarily by a suppression of photosynthesis whereas southeastern savannah carbon loss was driven in part by fire. We attribute the slow recovery to the unexpected large carbon loss caused by the severe atmospheric aridity coupled with a water storage deficit during drought. We show the attenuation of carbon uptake is three times higher than expected from the pre-drought sensitivity to atmospheric aridity and ground water supply. Our study fills an important knowledge gap in our understanding of the unexpectedly enhanced response of carbon fluxes to atmospheric aridity and water storage deficit and its impact on regional post-drought recovery as a function of the vegetation types and climate perturbations. Our results suggest that the disproportionate impact of water supply and demand could compromise resiliency of the Amazonian carbon balance to future increases in extreme events.

ABSTRACT Aim Location Taxon Methods Results Main Conclusions The aim of this study is to infer the geographic dispersal paths and the environmental conditions that shaped the historical biogeography of Brachistosternus scorpions in South America. We evaluated the role that altitude and aridity had on the geographic distance that each species dispersed from the location of the genus common ancestor. Based on the previous studies, we evaluated the hypothesis postulating that species geographic expansion was promoted by arid conditions in high altitudes.South America.Brachistosternus genus.We integrated two methodological approaches in this study, the phylogenetic Geographical model and the Conductance model, considering the uncertainty associated with the phylogenetic relationship and the species classification. The Geo model infers the locations of ancestral species in a phylogenetic tree, assuming a spherical space and using samples of georeferenced locations for every species as input data. It allows us to estimate the species dispersal routes and distances from the location of the genus common ancestor. The Conductance model is based on the circuit theory and infers the geographic route and distance of least resistance between an origin and destination point. We defined the origin as the location of the genus common ancestor obtained from the Geo model and a destination point as the current geographic location of each species. This model infers the geographic routes with the least cost of resistance for dispersal in a landscape of varying altitude and aridity. Finally, we evaluated the correlation between the two dispersal distances each species have moved from the location of the common ancestor, that is, the distance inferred from the Geo model and from the Conductance model.The Geo model shows that Brachistosternus's geographical origin was most likely along the coast of south Peru, and central Chile. From this location, extant species dispersed thorough routes ranging from 873 to 2800 km in average. The Conductance model that considers the routes with least resistance to elevation and aridity simulated dispersal distances that are highly correlated with the species dispersal distances obtained from the Geo model.We revealed the geographic dispersal routes, with the least resistance to the pressures imposed by changes in altitude and aridity, that 55 species of scorpions have probably followed in the last 30 million years in South America. These geographic routes that went along the Andean Mountains and the arid zones of South America shaped the current spatial distribution of the genus Brachistosternus. [ABSTRACT FROM AUTHOR]

Plants synthesize a broad array of specialized chemical compounds that mediate their interactions with the surrounding environment. Some of this chemical diversity is functional and subject to natural selection, but the factors underlying chemical evolution at the intraspecific level remain largely unknown. Here, we combined chemical, environmental and genetic data to investigate the effect of aridity on the expression of chemotypes in the invasive shrub Senecio pterophorus. We studied the variation in pyrrolizidine alkaloids (PAs), a group of specialized metabolites widespread across the families Boraginaceae, Asteraceae and Fabaceae, from native populations spanning a cline of aridity and from three cross‐continental introductions, under natural and common garden conditions. We examined whether the relationship between chemistry and aridity was compatible with a process of adaptive differentiation using a method that partitions the variance and covariance by controlling for the population neutral genetic structure. We found a consistent shift from retrorsine‐like to seneciphylline‐like compounds under increasing aridity in both natural and controlled conditions in coherence with the biosynthetic pathways. This pattern was independent of the neutral genetic structure and occurred along the environmental gradient in the native range and in a convergent manner in all nonnative regions, which suggests adaptive differentiation in response to aridity. Our findings show that the diversity of PAs in S. pterophorus has been partially shaped by aridity. Investigating how abiotic factors influence chemical evolution is key to elucidating the plant responses in future climate scenarios and the cascading effects on other trophic levels. [ABSTRACT FROM AUTHOR]

Drought poses a serious threat to Sudan, causing water shortages, crop failures, hunger, and conflict. The relationships between Indo-Pacific teleconnections and drought events in Sudan are examined based on the Standardized Precipitation Index (SPI), anomalies, Empirical Orthogonal Function (EOF), correlation, composite analysis, sequential Mann–Kendall test, and MK-trend test during the period of 1993–2022. The results of the SPI-1 values indicate that the extreme drought in Sudan in 2004 was an exceptional case that affected the entire region, with an SPI-1 value of −2 indicating extremely dry conditions. In addition, Sudan experienced moderate to severe drought conditions for several years (1993, 2002, 2008, 2009 and 2015). The Empirical Orthogonal Function showed that the first EOF mode (42.2%) was the dominant variability mode and had positive loading over most of the country, indicating consistent rainfall variation in the central, eastern, and western regions. Correlation analysis showed a strong significant relationship between June–September rainfall and Indian Ocean sea surface temperature (SST) (r ≤ 0.5). Furthermore, a weak positive influence of the Indian Ocean Dipole (IOD) on JJAS precipitation was observed (r ≤ 0.14). Various time lags in the range of ±12 months were examined, with the highest correlation (0.6) found at 9 month among the time lags of ±12 months. This study contributes to a better understanding of drought dynamics and provides essential information for effective drought management in Sudan. Further research is needed to explore the specific mechanisms driving these interactions and to develop tailored strategies to mitigate the impacts of drought events in the future. [ABSTRACT FROM AUTHOR]

Premise: Increasing aridity in the Mediterranean region affects ecosystems and plant life. Various anatomical changes in plants help them cope with dry conditions. This study focused on anatomical differences in leaves and xylem of five co‐occurring Mediterranean plant species namely Quercus calliprinos, Pistacia palaestina, Pistacia lentiscus, Rhamnus lycioides, and Phillyrea latifolia in wet and dry sites. Methods: Stomatal density, stomatal length, leaf mass area, lamina composition, percentage of intercellular air spaces, and mesophyll cell area in leaves of plants in wet and dry sites were analyzed. Xylem anatomy was assessed through vessel length and area in branches. Results: In the dry site, three species had increased stomatal density and decreased stomatal length. Four species had increased palisade mesophyll and reduced air space volume. In contrast, phenotypic changes in the xylem were less pronounced; vessel length was unaffected by site conditions, but vessel diameter decreased in two species. Intercellular air spaces proved to be the most dynamic anatomical feature. Quercus calliprinos had the most extensive anatomical changes; Rhamnus lycioides had only minor changes. All these changes were observed in comparison to the species in the wet site. Conclusions: This study elucidated variations in anatomical responses in leaves among co‐occurring Mediterranean plant species and identified the most dynamic traits. Understanding these adaptations provides valuable insights into the ability of plants to thrive under changing climate conditions. [ABSTRACT FROM AUTHOR]

The influence of climate on deep-time plant-insect interactions is becoming increasingly well known, with temperature, CO2 increases (and associated stoichiometric changes in plants), and aridity likely playing a critical role. In our modern climate, all three factors are shifting at an unprecedented rate, with uncertain consequences for biodiversity. To investigate effects of temperature, stoichiometry (specifically that of nitrogen), and aridity on insect herbivory, we explored insect herbivory in three modern floral assemblages and in 39 fossil floras, especially focusing on eight floras around a past hyperthermal event (the Paleocene-Eocene Thermal Maximum) from Bighorn Basin (BB). We find that higher temperatures were associated with increased herbivory in the past, especially among BB sites. In these BB sites, non-N2-fixing plants experienced a lower richness but higher frequency of herbivory damage than N2-fixing plants. Herbivory frequency but not richness was greater in BB sites compared with contemporaneous, nearby, but less arid sites from Hanna Basin. Compared with deep-time environments, herbivory frequency and richness are higher in modern sites, suggesting that current accelerated warming uniquely impacts plant-insect interactions. Overall, our work addresses multiple aspects of climate change using fossil data while also contextualizing the impact of modern anthropogenic change on Earth's most diverse interactions. [ABSTRACT FROM AUTHOR]

Climate‐vegetation interaction assessments often focus on vegetation response to concurrent climatic perturbations, seldom on the time‐lag effect of climate. Here we employ global satellite observations, climate data records and CO2 flux measurements to calculate the time‐lag of vegetation response to climate. We analyze the time‐lags of various climate variables under distinct environmental conditions to gain insight into how the long‐term climatic regimes and tree cover influence the time‐lag effects. Our findings reveal that terrestrial ecosystems characterized by arid and cold climates show more concurrent climate‐vegetation interactions than other ecosystems. Whereas areas with higher tree cover and humid ecosystems with both high mean annual temperature and precipitation show substantial time‐lag response of vegetation to climate by up to 6 months. Since the global climate‐vegetation interaction is dominated by time‐lag effects, incorporating these effects is paramount to improve our understanding of vegetation dynamics under a changing climate. Plain Language Summary: When studying how climate affects vegetation, many studies usually focus on immediate plant responses, without considering the long‐term effects of climate. In our study, we used satellite data to look at how plant photosynthesis and growth changed over time in response to concurrent and past climates. We found that in dry and cold areas, plants respond quickly to changes in climate. But in regions with high tree cover and humid climate, plant responses to climate can take up to 6 months. Understanding these delays is crucial for predicting how vegetation will respond as the climate changes around the world. Key Points: Terrestrial ecosystems with higher tree cover respond to climate perturbation more slowly than grasslands and croplandsTemperature consistently has more significant impacts on vegetation in the longer term than VPD and soil moistureArid and cold ecosystems show shorter time‐lag responses of vegetation to climate [ABSTRACT FROM AUTHOR]

Exploring the response of spatial and temporal characteristics of ecological quality change to aridity on the Qinghai–Tibet Plateau (QTP) can provide valuable information for regional ecological protection, water resource management, and climate change adaptation. In this study, we constructed the Remote Sensing Ecological Index (RSEI) and Standardized Precipitation Evapotranspiration Index (SPEI) based on the Google Earth Engine (GEE) platform with regional characteristics and completely analyzed the spatial and temporal variations of aridity and ecological quality on the QTP in the years 2000, 2005, 2010, 2015, and 2020. Additionally, we explored the responses of ecological quality to aridity indices at six different time scales. The Mann–Kendall test, correlation analysis, and significance test were used to study the spatial and temporal distribution characteristics of meteorological aridity at different time scales on the QTP and their impacts on the quality of the ecological environment. The results show that the ecological environmental quality of the QTP has a clear spatial distribution pattern. The ecological environment quality is significantly better in the south-east, while the Qaidam Basin and the west have lower ecological environment quality indices, but the overall trend of environmental quality is getting better. The Aridity Index of the QTP shows a differentiated spatial and temporal distribution pattern, with higher Aridity Indexes in the north-eastern and south-western parts of the plateau and lower Aridity Indexes in the central part of the plateau at shorter time scales. Monthly, seasonal, and annual-scale SPEI values showed an increasing trend. There is a correlation between aridity conditions and ecological quality on the QTP. The areas with significant positive correlation between the RSEI and SPEI in the study area were mainly concentrated in the south-eastern, south-western, and northern parts of the QTP, where the ecological quality of the environment is more seriously affected by meteorological aridity. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Location Time Period Major Taxa Studied Methods Results Main Conclusions Termites are a crucial group of macroinvertebrates regulating rates of deadwood decomposition across tropical and subtropical regions. When examining global patterns of deadwood decay, termites are treated as a homogenous group. There exist key biogeographical differences in termite distribution. One such clear distinction is the distribution of fungus‐growing termites (FGT, subfamily Macrotermitinae). Considering that climate will have shaped termite distribution and ecosystem processes, we evaluate the roles of termite distribution (presence of FGT) and climate (aridity) on global patterns in deadwood decay.Between 46° N‐43° S and 175° E‐85° W.Present (between 2016 and 2021).Termites (Blattodea: Termitoidae).We add salient data to an existing global dataset on deadwood decomposition, including new data from five existing sites and seven additional African sites. We analyse a dataset spanning six continents, 16 countries and 102 experimental sites. Firstly, we evaluate climatic differences (mean annual temperature, mean annual precipitation and mean annual aridity) between sites with and without FGT. Secondly, using aridity as a single comparative climate metric between sites that accounts for temperature and precipitation differences, we examine the interaction between FGT and aridity on global patterns of termite deadwood discovery and decay through multivariate logistic and linear regressions.Termite‐driven decay and wood discovery increased with aridity; however, responses differed between FGT and NFGT sites. Wood discovery increased with aridity in FGT sites only, suggesting a greater role of FGT to deadwood decay in arid environments. On average, both termite discovery and decay of deadwood were approximately four times greater in regions with FGT compared with regions without FGT.Termite discovery and decay of deadwood is climate dependent, and higher decay may be through greater discovery of deadwood in FGT sites. Inclusion of biogeographical differences in termite distribution could potentially alter current and future global estimates of deadwood turnover. [ABSTRACT FROM AUTHOR]

ABSTRACT Aim Location Time Period Major Taxa Studied Methods Results Main Conclusions To describe worldwide distribution of mammalian cradles and museums using the rates of phylogenetic lineage turnover as a surrogate. Additionally, we investigated the influences of current water–energy dynamics, climate instability, past climate changes and elevational ranges on the distribution of these evolutionary zones.Global.Current.Terrestrial mammals.We developed a new methodology that consists of calculating the spatial phylogenetic turnover for non‐overlapping temporal segments of phylogenetic trees. By calculating the relative turnover in each tree segment, we quantified the rate of accumulation of phylogenetic turnover through time. We depicted cold and hotspots of rates of lineage turnover using bivariate maps and examined the effects of environmental factors using a path model.The distributions of cradles and museums of biodiversity are primarily driven by water–energy dynamics. Environments with higher water availability than energetic demand predominantly act as cradles, as seen in tropical rainforests, while xeric‐like environments predominantly serve as museums. Conversely, regions undergoing higher historical climate changes become cradles, such as in higher northern latitudes, while climatically stable areas function as museums. Mountains play a dual role, acting as both cradles and museums by generating new lineages along their elevation bands while simultaneously providing climate refuges for ancient mammal lineages.Our findings demonstrate that cradles and museums are not merely a dichotomy but exist along an evolutionary continuum. Furthermore, they reveal how spatial patterns of mammalian cradles and museums are intricately shaped by biogeographical processes governed by environmental forces. Uncovering these hidden effects provides insights into the ecological mechanisms by which ongoing climate changes continually shape evolutionary assemblages over time. [ABSTRACT FROM AUTHOR]

Improved understanding of mosquito–plant feeding interactions can reveal insights into the ecological dynamics of pathogen transmission. In wild malaria vectors Anopheles gambiae s.l. and An. funestus group surveyed in selected dryland ecosystems of Kenya, we found a low level of plant feeding (2.8%) using biochemical cold anthrone test but uncovered 14-fold (41%) higher rate via DNA barcoding targeting the chloroplast rbcL gene. Plasmodium falciparum positivity was associated with either reduced or increased total sugar levels and varied by mosquito species. Gut analysis revealed the mosquitoes to frequently feed on acacia plants (~ 89%) (mainly Vachellia tortilis) in the family Fabaceae. Chemical analysis revealed 1-octen-3-ol (29.9%) as the dominant mosquito attractant, and the sugars glucose, sucrose, fructose, talose and inositol enriched in the vegetative parts, of acacia plants. Nutritional analysis of An. longipalpis C with high plant feeding rates detected fewer sugars (glucose, talose, fructose) compared to acacia plants. These results demonstrate (i) the sensitivity of DNA barcoding to detect plant feeding in malaria vectors, (ii) Plasmodium infection status affects energetic reserves of wild anopheline vectors and (iii) nutrient content and olfactory cues likely represent potent correlates of acacia preferred as a host plant by diverse malaria vectors. The results have relevance in the development of odor-bait control strategies including attractive targeted sugar-baits. [ABSTRACT FROM AUTHOR]

African savannah elephants (Loxodonta africana) are key ecosystem engineers that migrate over large spatiotemporal scales foraging as they require copious amounts of food and water across habitable landscapes. Therefore a need to understand movement patterns arises in relation to vegetation type and landscape variability, moreso in forage depauparate arid areas such as Gonarezhou National Park (GNP) in Zimbabwe. The objectives of this study were to: (i) assess the performance of vegetation indices in modelling the distribution of African savannah elephants, and (ii) model future landscape variability in Gonarezhou National Park (GNP) in Zimbabwe. Maximum entropy (MaxEnt) algorithm was used to explore the relationship between vegetation indices and distribution of African savannah elephants in the GNP. The Soil Adjusted Vegetation Index (SAVI) performs better relative to other indices in modelling the distribution of African savannah elephants across all habitat types in the GNP. Cellular automata‐Artificial Neural Network (CA‐ANN) showed a significant future decrease (Kruskal Anova; p < 0.05) in landscape suitable to sustain large populations of African savannah elephants in the GNP by the year 2083. Future remote sensing reveals directional insights into the future consequences of current landscape management for African savannah elephant conservation which is a crucial in the sustainability of climate threatened arid protected areas such as the GNP. [ABSTRACT FROM AUTHOR]

Mediterranean ecosystems are predicted to undergo longer and more intense summer droughts. The mechanisms underlying the response of herbaceous communities to such drier environments should be investigated to identify the resilience thresholds of Mediterranean rangelands. A 5‐year experiment was conducted in deep and shallow soil rangelands of southern France. A rainout shelter for 75 days in summer imposed drier and warmer conditions. Total soil water content was measured monthly to model available daily soil water. Aboveground net primary production (ANPP), forage quality, and the proportion of graminoids in ANPP were measured in spring and autumn. Plant senescence and plant cover were assessed in summer and spring, respectively. The experimental years were among the driest ever recorded at the site. Therefore, manipulated summer droughts were drier than long‐term ambient conditions. Interactions between treatment, community type, and experimental year were found for most variables. In shallow soil communities, spring plant cover decreased markedly with time. This legacy effect, driven by summer plant mortality and the loss of perennial graminoids, led to an abrupt loss of resilience when the extreme water stress index exceeded 37 mm 10 day−1, characterized by a reduction of spring plant cover below 50% and a decreased ANPP in rainy years. Conversely, the ANPP of deep soil communities remained unaffected by increased summer drought, although the presence of graminoids increased and forage nutritive value decreased. This study highlights the role of the soil water reserve of Mediterranean plant communities in modulating ecosystem responses to chronically intensified summer drought. Communities on deep soils were resilient, but communities on shallow soils showed a progressive, rapid, and intense degradation associated with a loss of resilience capacity. Notably, indexes of extreme stress were a better indicator of tipping points than indexes of integrated annual stress. Considering the role of soil water availability in other herbaceous ecosystems should improve the ability to predict the resilience of plant communities under climate change. [ABSTRACT FROM AUTHOR]

Understanding plant adaptive strategies to aridity is crucial for ecological research, particularly in the current context of climate change and increasing drought. This study focuses on the intraspecific phenotypic variation of the wild olive (Olea europaea subsp. europaea var. sylvestris), one of the most emblematic species of the Mediterranean Basin, widely distributed in Morocco. The research is based on measuring nine leaf and plant-size related traits in 130 trees across 13 populations under varying climate conditions and vegetation covers. The study explores the adaptive strategies of wild olive trees in response to increasing aridity and aridification. The results indicate that the nine traits exhibit significant covariation trends along environmental gradients, reflecting plant strategies related to resource acquisition, resource investment, and water use. Wild olive trees demonstrate substantial intraspecific variation both among and within populations in response to these environmental gradients. Climate, altitude, and vegetation cover together explain 93.8% of the trait covariations. The study elucidates the mechanisms underlying the adaptive strategies of wild olive trees to cope with stressful conditions. The findings suggest that wild olive trees adapt to stressful environments by adopting a conservative strategy, characterized by lower resource investment and higher water-use efficiency. This research underscores the importance of considering intraspecific variation in plant responses to environmental stressors and demonstrates the utility of trait-based approaches in understanding plant strategies under such conditions. [ABSTRACT FROM AUTHOR]

Twenty-five years after planting, we measured the survival, growth and reproduction of 153 Quercus ilex plantations promoted by the afforestation programme of the European Union's Common Agricultural Policy in agricultural fields in the east of the Iberian Peninsula, as a function of climatic aridity and stand characteristics related to water supply and competition among trees for water. Using field sampling, we found that, on average, 80% of the trees in plantations survived, more than 55% had already produced acorns and the tallest tree in each field exceeded 4 m, which are all higher values than those reported for forest plantations of this species in the same area and which represent the overcoming of the limitations imposed by climatic aridity on the natural regeneration of the species. A small proportion of the variation in all success variables was explained by water-related plantation characteristics, such as planting density, drought intensity in the year after planting, and soil permeability. However, climatic aridity only influenced the proportion of reproductive trees, but not the other variables of plantation success. However, most of the variation in planting success variables was linked to who owned the field, which nursery produced the seedlings, and the year of planting. Our results support the idea that the deep soils of agricultural fields counteract the negative effect of climatic aridity on plant performance, but that it is necessary to standardise nursery and planting practices, adapt planting density to the environmental characteristics of the site and provide irrigation supply in the early years to ensure the success of future plantations. [ABSTRACT FROM AUTHOR]

Land degradation is a global problem of mankind, the greatest contribution to which belongs to aridity and soil erosion. The social consequences of land degradation are extremely important, but poorly conceptualized issues. This makes it difficult to create effective research programs to study them. The article provides an overview of the issues under consideration. An expert study was conducted to identify a problem field in the field of studying the social consequences of land degradation. By interviewing nine recognized scientific experts in the field of land degradation studies, the most reliable judgments were identified, which served as a basis for highlighting the main forms of manifestation of the social consequences of land degradation. Private research concepts were compiled, which consist in highlighting the position of each expert on the main consequences of land degradation. As a result, a generalized expert model of the problem field of the social consequences of land degradation was formed. According the model all experts note the interdisciplinary nature of the study of the issues under consideration, which are placed at the intersection of environmental, economic, and social problems. The overwhelming majority of experts noted the direct nature of the effect of land degradation on the formation of social consequences. Thanks to the integration of individual ideas, it was possible to identify characteristics for which there are discrepancies. This provides an opportunity for a broader study of the social consequences of land degradation. However, there is an expert opinion that the social consequences are rather indirect and are realized through resource problems. Some experts draw attention to the fact that there are the extreme forms of land degradation that significantly increases the manifestation of social consequences. According to experts, land degradation can lead to change in social status, a decrease in the recreational potential of land, hunger, a change in life expectancy and loss of jobs, increased stratification of society, changes in the cost of housing and a change in the type of land use, reduction in the use of land for agricultural needs, and changes in people's attitudes to more individualistic ones. It was also noted that the use of products from degraded lands could lead to an increase in cancer incidence in the region. Conceptualization and identification of these problems could help to focus efforts in the field of studying the social problems of land degradation. [ABSTRACT FROM AUTHOR]

Mouse‐like rodents often take cover in natural shelters or burrow underground where they build simple nests. A few species build extensive shelters above ground, called lodges, mounds or houses. Here, we present the first phylogenetically controlled comparative study on the ecological factors of habitat heterogeneity, environmental aridity and fire risk related to nesting habits in mouse‐like rodents (Myomorpha, 326 genera). Twenty species from seven genera were found to build lodges, and they mainly occur in arid environments with low fire risk. Most lodge‐building species (14 out of 20) belong to the pack rats (genus Neotoma), which in phylogeny only represent one event of evolution of lodge building and therefore limit the statistical power of the phylogenetically controlled analysis. The Bayesian phylogenetic mixed‐effects models show a phylogenetic signal of 0.43 for 515 Myomorpha species. Under this moderate to strong phylogenetic relatedness, we did not find specific factors being associated to the evolution of sheltering habit in Myomorpha. We suggest studying the importance of aridity combined with low fire risk for lodge building on the species level, for example, by studying the limits of species distribution ranges depending on these factors. [ABSTRACT FROM AUTHOR]

Simple Summary: Climate change will cause a reduction in the provision of goods and services of Mediterranean forests, including those of stone pine (Pinus pinea), an economically important species. We used a dendrochronological approach to address climate impact on the growth of stone pine natural stands and plantations. Our results indicate that increasingly arid conditions will affect both natural stands and plantations in native and exotic countries. Adaptive management will be essential to ensure the maintenance of the stands and their multifunctionality. Pinus pinea is an important Mediterranean species due to its adaptability and tolerance to aridity and its high-quality pine nuts. Different forest types located in Mediterranean native and non-native environments provide the opportunity to perform comparative studies on the species' response to climate change. The aims of this study were to elucidate growth patterns of the species growing in native and exotic habitats and to analyze its response to climatic fluctuations, particularly drought, in both geographical contexts. Understanding stone pine (Pinus pinea) growth responses to climate variability in native and exotic habitats by comparing natural stands and plantations may provide useful information to plan adequate management under climate change. By doing so, we enhance the understanding of P. pinea's adaptability and provide practical approaches to its sustainable management. In this study, we reconstructed and compared the stem radial growth of seven stone pine stands, two in southern Spain and five in central–southern Chile, growing under different climatic conditions. We quantified the relationships between growth variability and climate variables (total rainfall, mean temperature, and SPEI drought index). Growth was positively correlated with autumn rainfall in plantations and with autumn–winter rainfall in natural stands. Growth was also enhanced by high autumn-to-spring rainfall in the driest Chilean plantation, whereas in the wettest and coolest plantation, such correlation was found in winter and summer. A negative impact of summer temperature was found only in one of the five Chilean plantations and in a Spanish site. The correlation between SPEI and tree-ring width indices showed different patterns between and within countries. Overall, exotic plantations showed lower sensitivity to climate variability than native stands. Therefore, stone pine plantations may be useful to assist in mitigating climate change. [ABSTRACT FROM AUTHOR]

Gypsum ecosystems occur in arid and semi-arid areas, where evaporation is intense and annual precipitation is low and insufficient to leach the gypsum. They host sparse and scattered vegetation, composed of species specialized in this soil type. In Cyprus, gypsophilous vegetation is part of the priority habitat *1520 Iberian gypsum steppes (Gypsophiletalia) characterized by Campanula fastigiata, Gypsophila linearifolia, and Teucrium salaminium. Despite the ecological importance of gypsophilous vegetation, its distribution and ecology in Cyprus is still understudied. This study aimed to provide the first comprehensive account of the gypsum communities, focusing on the distribution of gypsophytes in relation to the substrate and the floristic composition of gypsum soils. Floristic inventory was carried out in 27 sites with gypsum soil. Biophysical information and data about human impact were also recorded. A total of 97 taxa were identified, including three gyspophile species, two gypsoclines, 20 gypsovags, and 72 waifs. A new endemic Rostraria hadjikyriakou was recorded in five locations. The known geographical distribution of gypsophilous vegetation has been updated. For 35% of the sites, gypsophilous vegetation was recorded for the first time while none of the characteristic gypsophilous species was found in the western part of the island. [ABSTRACT FROM AUTHOR]

The analysis of the ASTC1 sediment core from the south Aegean Sea region offers critical insights into the complex interplay of geological and climatic factors over the Holocene period. The data reveals fluctuating climatic conditions during the last 8.7 ka as seen through the elemental concentrations obtained by XRF core scanning combined with a qualitative mineral analysis within a robust chronological framework. Short-term fluctuations in both Ti/Al and Zr/Si ratios suggest brief oscillations of increased aridity which partially coincide with the Holocene "Rapid Climate Change" events (RCCs). Among them, the most pronounced in our record are those centered between 8.5–8 ka, 3–2.5 ka (Greek Dark Ages), and 0.6–0.3 ka (Little Ice Age). The arid and humid events identified in the sediment record align with major archaeological periods in Greece, suggesting a potential influence of climatic conditions on the development and decline of civilizations in the region. Moreover, a general arid trend as of 6 ka toward the present was evidenced in our record and aligns with other high-resolution climatic data from the Northern Hemisphere, suggesting climatic teleconnections. Spectral analysis of the ASTC1 record reveals cyclical climate patterns with periodicities of approximately 2500, 1200, and 550 years, which coincide with the Bond and Hallstatt cycles. The phase relation of these cycles in our record, the Greenland ice record, and the North Atlantic Drift ice indices show that colder conditions in the higher latitudes are expressed as events of enhanced aridity in our record and generally in the lower latitudinal regions. [ABSTRACT FROM AUTHOR]

Soil microbial necromass carbon (MNC) contributes to the long-term stability of soil organic carbon (SOC). However, the response of MNC across aridity gradients remains unclear, especially in vulnerable alpine ecosystems. Here, we examined alpine grasslands from 180 sites spanning a 3,500 km aridity gradient on the Tibetan Plateau to investigate how MNC abundance and composition (contributions of bacterial and fungal necromass carbon) vary with climate. MNC was variable, ranging from 0.55 to 26.95 g kg−1 soil, with higher content observed in humid and dry-subhumid regions than in arid and semiarid regions in the Western Tibetan Plateau. Soil properties were the dominant drivers of MNC, with soil fertility (cation exchange capacity and total phosphorus) and weathering products (clay, silt and iron/aluminum oxides) facilitating MNC accumulation, while a negative correlation was observed between MNC and soil pH. A pivotal aridity threshold of 0.60 underpinned a non-linear decrease in MNC with increasing aridity across soil condition gradients; MNC was negatively correlated with aridity below this threshold and showed no correlation beyond it. Given this pivotal aridity threshold, we delineated the drivers of MNC under conditions of low (aridity < 0.6) versus high (aridity > 0.6) aridity. In low-aridity conditions, MNC accumulation was governed by aridity, soil fertility, weathering products, and pH, whereas in high-aridity conditions, the interplay between soil properties and temperature took precedence. Species richness enhanced carbon accumulation from microbial residues under low-aridity conditions more so than under high-aridity conditions, with fungal necromass carbon consistently being a higher contributor to SOC than bacterial necromass carbon, particularly in humid regions. These findings highlight aridity-driven divergence in MNC and propose that conserving plant diversity may mitigate the adverse effects of aridification on MNC under low-aridity conditions in alpine grasslands. [ABSTRACT FROM AUTHOR]

Despite hosting ∼16% of the global freshwater and almost 50% of water resources in South America, Brazilian catchment‐scale relationships between drivers and streamflow are still poorly understood. Here, we used streamflow signatures and attributes of 735 catchments from the Catchment Attributes for Brazil data set to investigate the dominant hydrological processes for the catchments. We also assess how catchments group based on hydrologic behavior similarities and analyze which climatic/landscape attributes control the streamflow variability. To classify and group the catchments, we used the k‐means method optimized by the Elbow approach, along with a Principal Component Analysis. Uncertainty on catchment grouping was checked by k‐fold cross‐validation. Then, we used a recursive feature elimination using the random forest technique to assess the most influential catchment attributes to the hydrological signatures. Our results revealed six similarity groups, which followed mainly an aridity gradient ranging from the wettest to the driest, but also seasonality. The climate is the primary driver of hydrological behavior for the water‐limited groups, highlighting the influence and importance of the atmospheric demand in several Brazilian catchments. High soil storage capacity in energy‐limited catchments associated with high precipitation led to high discharge all year due to the subsurface fluxes' contribution. Our findings may be useful to improve streamflow predictability and hydrological behavior identification by further understanding hydrological similarities and their signatures due to catchment landscape characteristics. Further, by employing an easily reproducible methodology and clear metrics to weigh uncertainty, our study provides a significant step toward establishing a catchment‐scale common classification system. Key Points: We analyzed catchment‐scale relationships between streamflow and its drivers by clustering the catchments based on hydrological similaritySix catchment groups emerged following mainly an aridity gradient, from the wettest to the driest, and seasonalityClimate controls the hydrological behavior of water‐limited catchments, while landscape characteristics control energy‐limited catchments [ABSTRACT FROM AUTHOR]

Downed woody debris is important for biodiversity, forest regeneration, and carbon, nutrient, and water cycling, and past studies have examined how the coarse fraction is affected by climate or harvesting. In a field study in Douglas-fir dominated forests, we expand existing knowledge by investigating the interacting effects of climate and harvesting on downed woody debris of all sizes. Across a 900-km long latitudinal gradient in British Columbia, we found that coarse woody debris (CWD, >7.5 cm diameter) in humid climates contained 700% greater carbon stocks, had 500% greater volume, and was more diverse than in arid climates. Pre- and post-harvest, small and fine woody debris comprised a higher proportion of total woody debris carbon stocks in arid than moist climates, especially after clearcutting and seed tree treatments. Harvesting generally decreased total CWD volume, but it was not depleted on any site. Harvesting substantially reduced the volume of large, highly decomposed CWD except at the two most arid sites, and losses of large CWD increased with increasing tree removal. These losses were accompanied by a pulse of fresh, small diameter CWD and SWD which are short-term organic nutrient sources but have less habitat value than larger pieces and contribute to fuel loads. Because CWD was less abundant in arid than humid mature forests, care must be taken on arid sites to avoid its depletion during harvesting, especially clearcutting, where future woody debris inputs will not occur for decades. [ABSTRACT FROM AUTHOR]

The grasslands in high-latitude areas are sensitive to climate warming and drought. However, the drought stress effect on the long-term variability of grassland productivity at the continental scale still hinders our understanding. Based on aboveground net primary production (ANPP) surveys, satellite remote sensing Normalized Difference Vegetation Index (NDVI), and meteorological data, we comprehensively analyzed three Aridity metrics and their effect on ANPP in Eurasian grassland from 1982 to 2020. Our results showed that the ANPP had an overall uptrend from 1982 to 2020, increasing most in the Tibetan Plateau alpine steppe subregion (TPSSR). Among three Aridity indicators, vapor pressure deficit (VPD) had an overall uptrend, while the trend of Aridity and soil moisture (SM) was insignificant from 1982 to 2020. Soil drought had negative effects on ANPP for all Eurasian grassland, while the atmospheric VPD had a positive effect on ANPP for TPSSR and the Mongolian Plateau steppe subregion (MPSSR), but a negative effect for the Black Sea–Kazakhstan steppe subregion (BKSSR) which was the driest subregion. SM had been the predominant driving factor for the interannual variability of ANPP in MPSSR since 1997. The increasing VPD had facilitated grassland productivity in alpine grasslands due to its cascading effect with an increasing temperature after 2000. The cascading effects networks of climate factors—drought factors (VPD, Aridity, and SM)—ANPP (CDA–CENet) indicated that SM was the predominant driving factor of the interannual variability of ANPP in MPSSR and BKSSR, and the dominance of SM had enhanced after the year 1997. The inhibitory effect of VPD on ANPP transformed into a facilitating effect after 1997, and the facilitating effect of SM is weakening in TPSSR. [ABSTRACT FROM AUTHOR]

Disturbances can produce a spectrum of short‐ and long‐term ecological consequences that depend on complex interactions of the characteristics of the event, antecedent environmental conditions, and the intrinsic properties of resistance and resilience of the affected biological system.We used Hurricane Harvey's impact on coastal rivers of Texas to examine the roles of storm‐related changes in hydrology and long‐term precipitation regime on the response of stream invertebrate communities to hurricane disturbance.We detected declines in richness, diversity and total abundance following the storm, but responses were strongly tied to direct and indirect effects of long‐term aridity and short‐term changes in stream hydrology. The amount of rainfall a site received drove both flood duration and flood magnitude across sites, but lower annual rainfall amounts (i.e. aridity) increased flood magnitude and decreased flood duration. Across all sites, flood duration was positively related to the time it took for invertebrate communities to return to a long‐term baseline and flood magnitude drove larger invertebrate community responses (i.e. changes in diversity and total abundance). However, invertebrate response per unit flood magnitude was lower in sub‐humid sites, potentially because of differences in refuge availability or ecological‐evolutionary interactions. Interestingly, sub‐humid streams had temporary large peaks in invertebrate total abundance and diversity following recovery period that may be indicative of the larger organic matter pulses expected in these systems because of their comparatively well‐developed riparian vegetation.Our findings show that hydrology and long‐term precipitation regime predictably affected invertebrate community responses and, thus, our work underscores the important influence of local climate to ecosystem sensitivity to disturbances. [ABSTRACT FROM AUTHOR]

Three Cenchrus species (C. biflorus, C. ciliaris, and C. orientalis) were collected from different ecological regions in the Punjab and Khyber Pakhtoonkhwa during July to September 2020 to evaluate tolerance to multiple abiotic stresses (aridity, salinity, and cold). Growth and biomass production was the maximum in C. biflorus, C. ciliaris, and C. orientalis under aridity stress. Aerenchyma formation and vascular tissue increased significantly in roots under aridity. In C. ciliaris, aerenchyma formation was recorded under cold stress. Root vascular tissue was higher under normal conditions (26.7%) and aridity (30.4%) stress in C. ciliaris. Stem parenchyma (29.1%) and vascular tissues (35.5%) showed an increase in C. biflorus under aridity, while mechanical tissue (33.6%) increased significantly under salinity stress. In C. biflorus and C. ciliaris, extensive sclerification was recorded in the stelar region under aridity stress. The stem radius of C. orientalis was greatest under salinity (27.0%) and cold (29.1%) stress, while parenchyma tissue was smaller (12.1%) under cold stress. Leaf thickness generally increased under abiotic stresses, and the maximum (43.0%) thickness was recorded in C. biflorus under aridity stress. Cenchrus biflorus, C. ciliaris, and C. orientalis showed strong association among morphological and leaf anatomical traits under aridity stress. Cenchrus orientalis showed high sclerification outside the vascular bundles of the leaf sheath. In saline conditions, vascular bundles were sclerified and enlarged. In and outside the vascular bundles of leaf blades, extensive sclerification was observed under cold stress conditions. Modifications in structural and functional traits were critical for the ecological success of Cenchrus species for survival in multiple environmental stresses. [ABSTRACT FROM AUTHOR]

This review presents a comprehensive examination of recent advancements in utilizing multi-date satellite data to analyze spatial and temporal variations in seasonal and inter-annual surface water dynamics within arid environments of Africa. Remote sensing offers continuous, precise, and long-term datasets for surface water research. Various sensors with differing spatial resolutions are discussed, with high-resolution multispectral sensors providing superior spatial resolution but at higher costs. Conversely, dualsensor approaches, incuding optical sensors (Sentinel-2 and Landsat), radar satellites (Sentinel-1 and RADARSAT) and UAVs were investigated. The review further examines the efficiency and applicability of traditional algorithms such as the modified normalized difference water index (MNDWI), normalized difference water index (NDWI), and automated water extraction index (AWEI) in detecting and delineating surface water resources. Additionally, machine learning (ML) algorithms, including support vector machines (SVM), Random Forest (RF), deep learning and emerging methodologies like recurrent tranformer networks, have been explored. Therefore, we recommend that future research endeavours focus on leveraging high-resolution satellite imagery and integrating physical models with deep learning techniques, artificial intelligence, and online big data processing platforms to improve surface water mapping capabilities. [ABSTRACT FROM AUTHOR]

In this study, the aridity index (AI) based on gridded climate data was validated for defining aridity and classifying aridity zones in Iraq through comparison with the results obtained by the station-based aridity index. Gauge-based gridded climate data taken from Climatic Research Unit Timeseries (CRU TS) were used to determine the annual value of four aridity indices (Lang, De Martonne, Ernic and UNEP AI) over the period 1998-2011. The results showed that the aridity distribution maps derived using grid-based aridity indices were reasonably close to those found using station-based ones. The four aridity indices properly identified similar aridity (dryness) classifications in both the station-based and grid-based aridity maps. The area percentage of each aridity class predicted by grid-based AIs was also compared with that obtained by the station-based AIs. The results showed that the variances between the area percentages predicted by grid-based AIs and those estimated using station-based AIs are fairly slight. The Lang AI exhibited the least variance (0.4%) while the De Martonne AI had the biggest variance (-4.8%). Despite these minor variances, it is however possible to conclude that the grid-based aridity index classified the aridity zones of Iraq as properly as the station-based aridity index did. [ABSTRACT FROM AUTHOR]

Mediterranean plants are facing increased periods of drought, potentially jeopardizing their survival. Despite the known influence of intraspecific variability on plants’ responses to the environment, most studies focus on differences between species and overlook short distances. Following the observation of three nearby populations of Quercus ilex and Cistus salviifolius inheriting different sets of drought-related functional traits in common garden, we tested if these populations could perform differently under water stress. We observed drought responses on plantlets from both species, measuring key physiological traits such as gas exchanges and spectrometric indexes. Our results show similar responses from populations of C. salviifolius while Q. ilex had high intraspecific variability, with increased drought-resistance in plants hailing from dry provenances, reflected by improved water use efficiency, photosynthetic capacity, and reduced metabolic response to stress. These observations support the idea that, despite the short distances, neighbouring plant populations can adapt differently to drought, changing the way they withstand climate and its changes.

Urbanization creates novel ecosystems comprised of species assemblages and environments with no natural analogue. Moreover, irrigation can alter plant function compared to non-irrigated systems. However, the capacity of irrigation to alter functional trait patterns across multiple species is unknown but may be important for the dynamics of urban ecosystems. We evaluated the hypothesis that urban irrigation influences plasticity in functional traits by measuring carbon-gain and water-use traits of 30 tree species planted in Southern California, USA spanning a coastal-to-desert gradient. Tree species respond to irrigation through increasing the carbon-gain trait relationship of leaf nitrogen per specific leaf area compared to their native habitat. Moreover, most species shift to a water-use strategy of greater water loss through stomata when planted in irrigated desert-like environments compared to coastal environments, implying that irrigated species capitalize on increased water availability to cool their leaves in extreme heat and high evaporative demand conditions. Therefore, irrigated urban environments increase the plasticity of trait responses compared to native ecosystems, allowing for novel response to climatic variation. Our results indicate that trees grown in water-resource-rich urban ecosystems can alter their functional traits plasticity beyond those measured in native ecosystems, which can lead to plant trait dynamics with no natural analogue.

This article explores the upper boundary of tree cover in drylands, specifically in arid and humid savannas. The researchers use data from the BIODESERT survey to test predictions made by Holdo & Nippert. The results show that the upper boundary on tree cover increases with mean annual precipitation up to a certain threshold, and then declines beyond that threshold. The study supports the mechanisms proposed by Holdo & Nippert, but also identifies some differences in the observed patterns. The findings suggest that factors such as competition for water, light limitation, and grazing can influence tree cover in savannas, and that future global change scenarios may further modify these mechanisms. [Extracted from the article]

Rising temperatures, increasing hydroclimate variability and intensifying disturbance regimes increase the risk of rapid ecosystem conversions. We can leverage multi‐proxy records of past ecosystem transformations to understand their causes and ecosystem vulnerability to rapid change.Prior to Euro‐American settlement, northern Indiana was a mosaic of prairie, oak‐dominated forests/woodlands and beech‐dominated hardwood forests. This heterogeneity, combined with well‐documented but poorly understood past beech population declines, make this region ideal for studying the drivers of ecosystem transformations.Here, we present a new record from Story Lake, IN, with proxies for vegetation composition (pollen), fire (charcoal) and beech intrinsic water use efficiency (δ13C of beech pollen; δ13Cbeech). Multiple proxies from the same core enable clear establishment of lead–lag relationships. Additionally, δ13Cbeech enables direct comparisons between beech population abundance and physiological responses to changing environments. We compare Story Lake to a nearby lake‐level reconstruction and to pollen records from nearby Pretty and Appleman Lakes and the distal Spicer Lake, to test hypotheses about synchrony and the spatial scale of governing processes.The 11.7 ka sediment record from Story Lake indicates multiple conversions between beech‐hardwood forest and oak forest/woodland. Beech pollen abundances rapidly increased between 7.5 and 7.1 ka, while oak declined. Oak abundances increased after 4.6 ka and remained high until 2.8 ka, indicating replacement of mesic forests by oak forest/woodland. At 2.8 ka, beech abundances rapidly increased, indicating mesic forest reestablishment. Beech and oak abundances correlate with charcoal accumulation rates but beech abundance is not correlated with δ13Cbeech.Fluctuations in beech abundances are synchronous among Story, Appleman and Pretty Lakes, but asynchronous between Story and Spicer Lakes, suggesting regulation by local‐scale vegetation‐fire‐climate feedbacks and secondarily by regional‐scale drivers.Holocene forest composition and fire dynamics appear to be closely co‐regulated and may be affected by local to regional climate variations. The importance of extrinsic drivers and positive/negative feedbacks changes over time, with higher ecoclimate sensitivity before 2.8 ka and greater resilience afterwards.Synthesis: Overall, oak‐ and beech‐dominated ecosystems were highly dynamic over the Holocene, with multiple ecosystem conversions driven by shifting interactions among vegetation, hydroclimate and fire regime. [ABSTRACT FROM AUTHOR]

The oxygen and hydrogen isotopic composition (δ18O, δ2H) of plant tissues are key tools for the reconstruction of hydrological and plant physiological processes and may therefore be used to disentangle the reasons for tree mortality. However, how both elements respond to soil drought conditions before death has rarely been investigated. To test this, we performed a greenhouse study and determined predisposing fertilization and lethal soil drought effects on δ18O and δ2H values of organic matter in leaves and tree rings of living and dead saplings of five European tree species. For mechanistic insights, we additionally measured isotopic (i.e. δ18O and δ2H values of leaf and twig water), physiological (i.e. leaf water potential and gas-exchange) and metabolic traits (i.e. leaf and stem non-structural carbohydrate concentration, carbon-to-nitrogen ratios). Across all species, lethal soil drought generally caused a homogenous 2H-enrichment in leaf and tree-ring organic matter, but a low and heterogenous δ18O response in the same tissues. Unlike δ18O values, δ2H values of tree-ring organic matter were correlated with those of leaf and twig water and with plant physiological traits across treatments and species. The 2H-enrichment in plant organic matter also went along with a decrease in stem starch concentrations under soil drought compared with well-watered conditions. In contrast, the predisposing fertilization had generally no significant effect on any tested isotopic, physiological and metabolic traits. We propose that the 2H-enrichment in the dead trees is related to (i) the plant water isotopic composition, (ii) metabolic processes shaping leaf non-structural carbohydrates, (iii) the use of carbon reserves for growth and (iv) species-specific physiological adjustments. The homogenous stress imprint on δ2H but not on δ18O suggests that the former could be used as a proxy to reconstruct soil droughts and underlying processes of tree mortality. [ABSTRACT FROM AUTHOR]

Global warming is one of the most pressing challenges of our time, contributing to climate change effects and with far-reaching implications for built environments. The main aim of this study is to assess the extent to which Annaba city, Algeria, as part of the Mediterranean region, is affected by global climate change and its broader influences. The study investigated climatic shifts in Annaba city, using a multi-step methodology integrating data collection and analysis techniques. Data collection included 23 years of climate data (2000–2023) from Annaba's meteorological station, on-site measurements of microclimatic variations, and a questionnaire survey. The collected data underwent four main analyses: a time series analysis to describe climate parameters over 23 years, a statistical analysis to predict potential future climatic conditions (2024–2029) and the correlation of various climatic variables using specialized bioclimate tools to highlight seasonal variability, a spatial study of the urban heat island (UHI) phenomenon and perceived climatic shifts, and an analysis of extreme weather events characterizing heat atmospheric events in the context of urban climate change in the Mediterranean region. The findings revealed a consistent warming trend in Annaba city, with prolonged extreme climate conditions observed, particularly in the last four years (2020–2023). Significant temperature fluctuations were emphasized, notably in July 2023, with record-breaking maximum temperatures reaching 48.2 °C, the hottest on record with an increase of 3.8 °C, and presenting challenges amplified by the urban heat island effect, causing temperature differentials of up to 6 °C within built-up areas. Projections for 2029 suggest a tendency towards heightened aridity with a significant shift towards a new climate seasonality featuring two distinct main seasons—moderate and hot challenging. The abrupt disruption of calm weather conditions in Annaba on 24 July 2023 highlighted the influence of atmospheric circulation within the Mediterranean region featured for both anticyclones and atmospheric blocking phenomena on local weather patterns. [ABSTRACT FROM AUTHOR]

Venus is Earth's sister planet, with similar mass and density but an uninhabitably hot surface, an atmosphere with a water activity 50–100 times lower than anywhere on Earths' surface, and clouds believed to be made of concentrated sulfuric acid. These features have been taken to imply that the chances of finding life on Venus are vanishingly small, with several authors describing Venus' clouds as "uninhabitable," and that apparent signs of life there must therefore be abiotic, or artefactual. In this article, we argue that although many features of Venus can rule out the possibility that Earth life could live there, none rule out the possibility of all life based on what we know of the physical principle of life on Earth. Specifically, there is abundant energy, the energy requirements for retaining water and capturing hydrogen atoms to build biomass are not excessive, defenses against sulfuric acid are conceivable and have terrestrial precedent, and the speculative possibility that life uses concentrated sulfuric acid as a solvent instead of water remains. Metals are likely to be available in limited supply, and the radiation environment is benign. The clouds can support a biomass that could readily be detectable by future astrobiology-focused space missions from its impact on the atmosphere. Although we consider the prospects for finding life on Venus to be speculative, they are not absent. The scientific reward from finding life in such an un-Earthlike environment justifies considering how observations and missions should be designed to be capable of detecting life if it is there. [ABSTRACT FROM AUTHOR]

Based on the daily meteorological observation data of seven meteorological stations in southern Tibet from 1980 to 2021 (April October), the temporal and spatial variation characteristics and influencing factors of aridity index (AI) in the growing season of major grain producing areas in Tibet were studied by using climate tendency rate, Mann-Kendal test, Morlet wavelet analysis, GIS hybrid interpolation method, Pearson correlation coefficient, contribution rate analysis and other methods. The results showed that the average Al in the main grain producing areas of Tibet was 1.7, which belonged to the semi-arid area, and the overall trend was decreasing (humidifying) (-0.036/10 a). The linear decreasing trend was different in different regions, and the area around Lhatse County was the most significant (-0.26/10 a). Al had no obvious abrupt change, and had long- and medium-term fluctuation characteristics of 24 years, 6 years. The spatial dis- tribution was uneven, and had the characteristics of 'shrinking arid area and expanding humid area'. The contribution rates of the main climate influencing factors of Al varied in different regions. In general, the contribution rates after quantification was as follows: precipitation (34.9%) > relative humidity (28.4%) > sun- shine (19.9%) > maximum temperature (12.4%). [ABSTRACT FROM AUTHOR]

Drylands, comprising semi‐arid, arid, and hyperarid regions, cover approximately 41% of the Earth's land surface and have expanded considerably in recent decades. Even under more optimistic scenarios, such as limiting global temperature rise to 1.5°C by 2100, semi‐arid lands may increase by up to 38%. This study provides an overview of the state‐of‐the‐art regarding changing aridity in arid regions, with a specific focus on its effects on the accumulation and availability of carbon (C), nitrogen (N), and phosphorus (P) in plant–soil systems. Additionally, we summarized the impacts of rising aridity on biodiversity, service provisioning, and feedback effects on climate change across scales. The expansion of arid ecosystems is linked to a decline in C and nutrient stocks, plant community biomass and diversity, thereby diminishing the capacity for recovery and maintaining adequate water‐use efficiency by plants and microbes. Prolonged drought led to a −3.3% reduction in soil organic carbon (SOC) content (based on 148 drought‐manipulation studies), a −8.7% decrease in plant litter input, a −13.0% decline in absolute litter decomposition, and a −5.7% decrease in litter decomposition rate. Moreover, a substantial positive feedback loop with global warming exists, primarily due to increased albedo. The loss of critical ecosystem services, including food production capacity and water resources, poses a severe challenge to the inhabitants of these regions. Increased aridity reduces SOC, nutrient, and water content. Aridity expansion and intensification exacerbate socio‐economic disparities between economically rich and least developed countries, with significant opportunities for improvement through substantial investments in infrastructure and technology. By 2100, half the world's landmass may become dryland, characterized by severe conditions marked by limited C, N, and P resources, water scarcity, and substantial loss of native species biodiversity. These conditions pose formidable challenges for maintaining essential services, impacting human well‐being and raising complex global and regional socio‐political challenges. [ABSTRACT FROM AUTHOR]

Canopy structural complexity is a key emergent property of forest ecosystems that directly relates to their ability to store carbon, cycle water and nutrients, and provide habitat for biodiversity. However, we lack a general framework for quantifying the structural complexity of forest canopies, and it remains to be seen if there are simple rules that explain the huge variation in canopy structure that we observe across the world's forests.A leading candidate for characterizing differences in structural complexity among forest ecosystems are fractal scaling laws, or measures of statistical self‐similarity. If forest canopies were fractal in nature, their structural attributes could be distilled into a single coefficient—their fractal dimension—which could then be used to directly compare structural differences within and across biomes.To test this idea, we used airborne laser scanning (ALS) data acquired across nine landscapes in Australia that span a huge environmental gradient and include everything from dry shrublands, tropical savannas, dense rainforests, to 90 m tall Mountain Ash forests. Using the ALS data, we built high‐resolution 3D canopy height models of each landscape so that we could quantify how closely they followed fractal scaling laws, based on a comprehensive set of fractal dimension estimators.Across all ecosystem types, fractal scaling assumptions were consistently violated, with clear and systematic differences between real‐world forest canopies and simulated fractal surfaces. However, deviations from fractality did vary predictably among sites, with forests in less arid environments, dominated by tall trees with large crowns, exhibiting a higher degree of self‐similarity across scales.Synthesis: Our study conclusively shows that canopy surfaces are not fractal beyond the scale of individual tree crowns. Nevertheless, we still observed ecologically meaningful and generalisable patterns in forest structure across scales, which closely reflect biophysical and physiological constraints on tree size and architecture. These patterns point the way towards a more general framework for characterizing ecological complexity. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyze the ecogeographical distribution of poisonous plants in floristic regions of Kazakhstan and identify the effect of arid conditions on their distribution. In total, the 51 most toxic vascular plant species belonging to 34 families were identified in the republic. Cartographic analysis showed that the lesser part of these species are confined to plain floristic regions in northern deserts; while mountain steppe regions have the greater part of toxic species. The largest numbers of poisonous plant species were recorded in the following floristic regions: Western Tien Shan, Tarbagatai, and Altai; the smallest numbers, in Mangyshlak, Northern and Southern Ustyurt, and Buzachi. [ABSTRACT FROM AUTHOR]

Abstract During the 2015–2016 El Niño, the Amazon basin released almost one gigaton of carbon (GtC) into the atmosphere due to extreme temperatures and drought. The link between the drought impact and recovery of the total carbon pools and its biogeochemical drivers is still unknown. With satellite‐constrained net carbon exchange and its component fluxes including gross primary production and fire emissions, we show that the total carbon loss caused by the 2015–2016 El Niño had not recovered by the end of 2018. Forest ecosystems over the Northeastern (NE) Amazon suffered a cumulative total carbon loss of ∼0.6 GtC through December 2018, driven primarily by a suppression of photosynthesis whereas southeastern savannah carbon loss was driven in part by fire. We attribute the slow recovery to the unexpected large carbon loss caused by the severe atmospheric aridity coupled with a water storage deficit during drought. We show the attenuation of carbon uptake is three times higher than expected from the pre‐drought sensitivity to atmospheric aridity and ground water supply. Our study fills an important knowledge gap in our understanding of the unexpectedly enhanced response of carbon fluxes to atmospheric aridity and water storage deficit and its impact on regional post‐drought recovery as a function of the vegetation types and climate perturbations. Our results suggest that the disproportionate impact of water supply and demand could compromise resiliency of the Amazonian carbon balance to future increases in extreme events.

Downed woody debris is important for biodiversity, forest regeneration, and carbon, nutrient, and water cycling, and past studies have examined how the coarse fraction is affected by climate or harvesting. In a field study in Douglas-fir dominated forests, we expand existing knowledge by investigating the interacting effects of climate and harvesting on downed woody debris of all sizes. Across a 900-km long latitudinal gradient in British Columbia, we found that coarse woody debris (CWD, >7.5 cm diameter) in humid climates contained 700% greater carbon stocks, had 500% greater volume, and was more diverse than in arid climates. Pre- and post-harvest, small and fine woody debris comprised a higher proportion of total woody debris carbon stocks in arid than moist climates, especially after clearcutting and seed tree treatments. Harvesting generally decreased total CWD volume, but it was not depleted on any site. Harvesting substantially reduced the volume of large, highly decomposed CWD except at the two most arid sites, and losses of large CWD increased with increasing tree removal. These losses were accompanied by a pulse of fresh, small diameter CWD and SWD which are short-term organic nutrient sources but have less habitat value than larger pieces and contribute to fuel loads. Because CWD was less abundant in arid than humid mature forests, care must be taken on arid sites to avoid its depletion during harvesting, especially clearcutting, where future woody debris inputs will not occur for decades.

The investigation of the genetic variability of barley varieties is particularly important in the context of a changing climate and the need to ensure agricultural productivity in the face of environmental challenges. The purpose of the study was to assess the tolerance of barley varieties to soil salinity in order to identify the most productive and adapted varieties. To achieve this goal, the salt tolerance of barley varieties was diagnosed and varieties that showed high resistance to salinity were identified. As a result of a study of 45 varieties of barley, it was found that 37 of them showed salt tolerance, but as they grew, some of them could not cope with salinization and stopped their development. Of these 37 varieties, 13 genotypes were selected, which had real salt tolerance and continued to grow and develop under stressful conditions, having the ability to give a satisfactory yield in comparison with the standard variety. These varieties are successfully used as testers in hybrid crosses and have a combination of useful characteristics, which makes them valuable for agricultural practice. The study also showed that different characteristics have different degrees of genetic variability. Thus, according to the data obtained, the number of grains in the ear and the weight of 1000 grains have high genetic variability, indicating the importance of genetic factors in their formation. These characteristics play a key role in the selection of plants to increase the yield and quality of grain. The results obtained are of practical importance for agricultural producers, as they can more accurately choose barley varieties that are most suitable for local conditions. This contributes to an increase in yield and product quality, which is important for ensuring food security and economic efficiency of agriculture

Drought poses a serious threat to Sudan, causing water shortages, crop failures, hunger, and conflict. The relationships between Indo-Pacific teleconnections and drought events in Sudan are examined based on the Standardized Precipitation Index (SPI), anomalies, Empirical Orthogonal Function (EOF), correlation, composite analysis, sequential Mann–Kendall test, and MK-trend test during the period of 1993–2022. The results of the SPI-1 values indicate that the extreme drought in Sudan in 2004 was an exceptional case that affected the entire region, with an SPI-1 value of −2 indicating extremely dry conditions. In addition, Sudan experienced moderate to severe drought conditions for several years (1993, 2002, 2008, 2009 and 2015). The Empirical Orthogonal Function showed that the first EOF mode (42.2%) was the dominant variability mode and had positive loading over most of the country, indicating consistent rainfall variation in the central, eastern, and western regions. Correlation analysis showed a strong significant relationship between June–September rainfall and Indian Ocean sea surface temperature (SST) (r ≤ 0.5). Furthermore, a weak positive influence of the Indian Ocean Dipole (IOD) on JJAS precipitation was observed (r ≤ 0.14). Various time lags in the range of ±12 months were examined, with the highest correlation (0.6) found at 9 month among the time lags of ±12 months. This study contributes to a better understanding of drought dynamics and provides essential information for effective drought management in Sudan. Further research is needed to explore the specific mechanisms driving these interactions and to develop tailored strategies to mitigate the impacts of drought events in the future.

Exploring the response of spatial and temporal characteristics of ecological quality change to aridity on the Qinghai–Tibet Plateau (QTP) can provide valuable information for regional ecological protection, water resource management, and climate change adaptation. In this study, we constructed the Remote Sensing Ecological Index (RSEI) and Standardized Precipitation Evapotranspiration Index (SPEI) based on the Google Earth Engine (GEE) platform with regional characteristics and completely analyzed the spatial and temporal variations of aridity and ecological quality on the QTP in the years 2000, 2005, 2010, 2015, and 2020. Additionally, we explored the responses of ecological quality to aridity indices at six different time scales. The Mann–Kendall test, correlation analysis, and significance test were used to study the spatial and temporal distribution characteristics of meteorological aridity at different time scales on the QTP and their impacts on the quality of the ecological environment. The results show that the ecological environmental quality of the QTP has a clear spatial distribution pattern. The ecological environment quality is significantly better in the south-east, while the Qaidam Basin and the west have lower ecological environment quality indices, but the overall trend of environmental quality is getting better. The Aridity Index of the QTP shows a differentiated spatial and temporal distribution pattern, with higher Aridity Indexes in the north-eastern and south-western parts of the plateau and lower Aridity Indexes in the central part of the plateau at shorter time scales. Monthly, seasonal, and annual-scale SPEI values showed an increasing trend. There is a correlation between aridity conditions and ecological quality on the QTP. The areas with significant positive correlation between the RSEI and SPEI in the study area were mainly concentrated in the south-eastern, south-western, and northern parts of the QTP, where the ecological quality of the environment is more seriously affected by meteorological aridity.

Salinity is an important water quality parameter that affects ecosystem health and the use of freshwaters for industrial, agricultural, and other beneficial purposes. Although a number of studies have investigated the variability and trends of salinity in rivers and streams, the effects of floods on salinity across a wide range of watersheds have not been determined. Here, we examine this question by utilizing long-term observational records of daily streamflow and specific conductance (SC; a proxy for salinity) in addition to catchment characteristics for 259 United States Geological Survey (USGS) monitoring sites in the contiguous United States spanning a wide range of climatic, geologic and hydrologic conditions. We used a combination of statistical methods, random forest machine learning models, and information-theoretic causal inference algorithms to determine the response of SC to floods and the factors that impact salinity changes within sites (intra-site variability) and across sites (inter-site variability). Our results show that changes to SC during flood events exhibited substantial variability ranging from a 100% decrease to 34% increase relative to the long-term mean. We found that dilution is the prevailing mechanism that decreases SC levels during floods for most sites, but other mechanisms caused an increase of SC for 6.1% (n = 5521) of flood events. Our analysis revealed that antecedent conditions of SC in the few days preceding the flood are the most important factor in explaining intra-site variability. The response of salinity to floods also varied considerably across sites with different characteristics, with a notable effect of urbanization in temperate climates resulting in increased dilution of SC, and mining in arid climates, which adversely increases SC levels. Overall, we find that the combined effect of aridity and anthropogenic factors is of primary importance in determining how salinity responds to floods, and it bears strongly on water quality conditions in a future world - one in which floods are expected to increase in frequency and intensity, concurrent with shifting aridity patterns and increasing urbanization.