Search

This study analyzes the temporal patterns of rainfed cereal phenology extracted from the GIMMS NDVI3g dataset in the main cereal-growing regions under a Mediterranean climate in Spain, Portugal, France and Italy during the period 1982–2022. The series before and after the beginning of the 21st century were analyzed separately. Phenological parameters were extracted using the modified dynamic threshold method, and their trends were analyzed. Correlation analyses were performed to study the relationships among these parameters and to analyze the influence of hydroclimatic variables on the start (SOS) and end (EOS) of the growing season. Results showed a temporal reversal in phenological trends between both study periods, coinciding with the global warming hiatus. In the first period (1982–2002), SOS and EOS advanced (−7.5 and −3.1 days, respectively), and the length of growing season (LOS) increased. However, during the second stage (2003–2022), SOS and EOS were delayed (7.5 and 1.7 days, respectively), and LOS decreased. Similar dynamics were observed for the influence of the hydroclimatic variables on SOS and EOS, stronger in the first period and weaker in the second. This study provides valuable information on the phenological dynamics of rainfed cereals that may be useful for their management and planning in climate change scenarios. [ABSTRACT FROM AUTHOR]

Summary: Understanding the capacity of temperate trees to acclimate to limited soil water has become essential in the face of increasing drought risk due to climate change. We documented seasonal – or phenological – patterns in acclimation to water deficit stress in stems and leaves of tree species spanning the angiosperm phylogeny.Over 3 yr of field observations carried out in two US arboreta, we measured stem vulnerability to embolism (36 individuals of 7 Species) and turgor loss point (119 individuals of 27 species) over the growing season. We also conducted a growth chamber experiment on 20 individuals of one species to assess the mechanistic relationship between soil water restriction and acclimation.In three‐quarters of species measured, plants became less vulnerable to embolism and/or loss of turgor over the growing season. We were able to stimulate this acclimatory effect by withholding water in the growth chamber experiment.Temperate angiosperms are capable of acclimation to soil water deficit stress, showing maximum vulnerability to soil water deficits following budbreak and becoming more resilient to damage over the course of the growing season or in response to simulated drought. The species‐specific tempo and extent of this acclimatory potential constitutes preadaptive climate change resilience. [ABSTRACT FROM AUTHOR]

Addressing impacts of flash droughts (FDs) on the water‐food nexus requires a understanding of FD mechanisms and drivers at the watershed level. Examining climatic drivers, dry and wet spell lengths from 1980 to 2019, we analyzed FD spatial and temporal characteristics, emphasizing areal extent, onset time, and duration. Our findings reveal substantial variations in FDs among different watersheds. Notably, watersheds in the Southern Hemisphere are witnessing expanding, faster‐developing, and longer‐lasting FDs, aligning with climate variations in precipitation and temperature. Additionally, at the watershed scale, the onset and duration of FDs are more influenced by the intensity (magnitude and variability) of climatic drivers than the average length of wet and dry periods. FD‐extents, however, correlate with both climatic conditions and wet and dry periods, underscoring watershed connectivity. Ultimately, our results underscore the necessity for research to comprehend the interplay between FDs and watershed characteristics and how it manifests in overall water resource management. Plain Language Summary: Flash droughts (FDs), which are sudden and severe dry periods, are causing problems for our water and food systems and making it harder to prepare for disasters. To address these challenges effectively, it is crucial to gain a thorough understanding of the underlying mechanisms and factors driving FDs at the watershed level. In this study, we looked at climatic patterns alongside the lengths of dry and wet periods spanning from 1980 to 2019. Our primary focus was on three key aspects: the extent of FDs, when they begin, and how long they persist. Our research findings demonstrate considerable variations in FDs occurrences across different regions. Notably, in the Southern Hemisphere, FDs are expanding rapidly, developing more swiftly, and enduring for extended periods, closely mirroring shifts in precipitation and temperature patterns. Interestingly, the onset and duration of FDs seem to depend more on the intensity of climatic factors than on how long it's been dry or wet. The expansion of FDs in a region is linked to both the climatic and dry/wet periods, emphasizing the geophysical connectivity within a watershed. Key Points: Watersheds in tropical, temperate climates, and with savanna and grassland land cover are more susceptible to flash droughts (FDs)FDs extents are affected by intraannual precipitation variability, but not by intraannual air temperature variabilityThe onset and duration of FD at the watershed scale are influenced more by climate variables, than average wet/dry spell periods [ABSTRACT FROM AUTHOR]

[Display omitted] A troubling feedback loop, where drier soil contributes to hotter climates, has been widely recognized. This study, drawing on climate model simulations, reveals that maintaining current global soil moisture levels could significantly alleviate 32.9% of land warming under low-emission scenarios. This action could also postpone reaching critical warming thresholds of 1.5 °C and 2.0 °C by at least a decade. Crucially, preserving soil moisture at current levels could prevent noticeable climate change impacts across 42% of the Earth's land, a stark deviation from projections suggesting widespread impacts before the 2060s. To combat soil drying, afforestation in mid-to-low latitude regions within the next three decades is proposed as an effective strategy to increase surface water availability. This underscores the substantial potential of nature-based solutions for managing soil moisture, benefiting both climate change mitigation and ecological enhancement. [ABSTRACT FROM AUTHOR]

Organic peat soils occupy relatively little of the global land surface area but store vast amounts of soil carbon in northern latitudes where climate is warming at a rapid pace. Warming may result in strong positive feedbacks of carbon loss and global climate change driven by microbial processes if warming alters the balance between primary productivity and decomposition. To elucidate effects of warming on the microbial communities mediating peat carbon dynamics, we explored the abundance of broad microbial groups and their source of carbon (i.e. old carbon versus more recently fixed photosynthate) using microbial lipid analysis (δ13C PLFA) of peat samples under ambient temperatures and before/after initiation of experimental peat warming (+ 2.25, + 4.5, + 6.75, and + 9 °C). This analysis occurred over a profile to 2 m depth in an undrained, ombrotrophic peat bog in northern Minnesota. We found that the total microbial biomass and individual indicator lipid abundances were stratified by depth and strongly correlated to temperature under ambient conditions. However, under experimental warming, statistically significant effects of temperature on the microbial community were sporadic and inconsistent. For example, 3 months after experimental warming the relative abundance of Gram-negative bacterial indicators across depth combined and > 50 cm depth and Gram-positive bacterial indicators at 20–50 cm depth showed significant positive relationships to temperature. At that same timepoint, however, the relative abundance of Actinobacterial indicators across depth showed a significant negative relationship to temperature. After 10 months of experimental warming, the relative abundance of fungal biomarkers was positively related to temperature in all depths combined, and the absolute abundance of anaerobic bacteria declined with increasing temperature in the 20–50 cm depth interval. The lack of observed response in the broader microbial community may suggest that at least initially, microbial community structure with peat depth in these peatlands is driven more by bulk density and soil water content than temperature. Alternatively, the lack of broad microbial community response may simply represent a lag period, with more change to come in the future. The long-term trajectory of microbial response to warming in this ecosystem then could either be direct, after this initial lag time, or indirect through other physical or biogeochemical changes in the peat profile. These initial results provide an important baseline against which to measure long-term microbial community and carbon-cycling responses to warming and elevated CO2. [ABSTRACT FROM AUTHOR]

Climate change significantly affects crop production and is a threat to global food security. Conventional tillage (CT) is the primary tillage practice in rain-fed areas to conserve soil moisture. Despite previous research on the effect of tillage methods on different cropping systems, a comparison of tillage methods on soil water storage, crop yield and crop water use in wheat (Triticum aestivum) and maize (Zea mays) under different soil textures, precipitation and temperature patterns is needed. We reviewed 119 published articles and used meta-analysis to assess the effects of three conservation tillage practices (NT, no-tillage; RT, reduced tillage; ST, subsoil tillage), on precipitation storage efficiency (PSE), soil water storage at crop planting (SWSp), grain yield, evapotranspiration (ET) and water use efficiency (WUE) under varying precipitation and temperature patterns and soil textures in dryland wheat and maize, with CT as the control treatment. Conservation tillage methods increased PSE, SWSp, grain yield, ET and WUE in both winter wheat-fallow and spring maize cropping systems. More precipitation water was conserved in fine-textured soils than in medium-textured and coarse-textured soils, which improved ET. Conservation tillage increased soil water conservation and yield under high mean annual precipitation (MAP) and moderate mean annual temperature (MAT) conditions in winter wheat. However, soil water conservation and yield were greater under MAP <400 mm and moderate MAT. We conclude that conservation tillage could be promising for increasing precipitation storage, soil water conservation and crop yield in regions with medium to low MAPs and medium to high MATs. [ABSTRACT FROM AUTHOR]

Agricultural production across the African continent is subjected to various effects of climate variability. One of the main staple foods in Sub-Saharan Africa is maize. However, limited scientific research has recently focused on understanding the possible effects of hydro-climatic variability on maize production. The aim of the present work was to contribute to policy and climate adaptation, thus reducing the vulnerability of maize production to climate change over Equatorial Africa. This study firstly examined long-term trends of precipitation (PRE), soil moisture (SM), actual evapotranspiration (E), and potential evapotranspiration (Ep), as well as surface air temperatures, including the minimum (TMIN) and maximum (TMAX). Secondly, the relationship between maize production and these climate variables was quantified for 18 Equatorial African countries (EQCs) over 1980−2021. To assess the linear trends, Mann–Kendall and Sen's slope tests were used to quantify the magnitude of the hydro-climatic variable trends at the 5% significance level, and Pearson's correlation coefficient was used to evaluate the relation of these climate parameters with the maize production. The annual mean PRE declined at 0.03 mm day−110a−1. Other climate variables increased at different rates: SM at 0.02 mmday−110a−1, E at 0.03 mm day−110a−1, Ep at 0.02 mm day−1 10a−1, TMIN and TMAX at 0.01 °C day−110a−1. A regional analysis revealed heterogeneous significant wet–dry and warm–cool trends over the EQCs. While, spatially, dry and warm climates were observed in the central to eastern areas, wet and warm conditions dominated the western regions. Generally, the correlations of maize production with the E, Ep, TMAX, and TMIN were strong (r > 0.7) and positive, while moderate (r > 0.45) correlations of maize production with PRE and SM were obvious. These country-wide analyses highlight the significance of climate change policies and offer a scientific basis for designing tailored adaptation strategies in rainfed agricultural regions. [ABSTRACT FROM AUTHOR]

Evapotranspiration affects uncertain changes in volumetric soil moisture content (θ) of earth surface, which is considerably controlled by temporal variability of weather parameters like rainfall and ambient temperature. Accurate measurement of temporal variation and spatial distribution of θ in a particular land is very challenging. Numerical modelling with any suitable computer code might be useful in such cases. Thus, Hydrus 2D modelling of θ variation in the soil at Odisha University of Agriculture and Technology (OUAT) in Bhubaneswar is undertaken as main objective of present study to investigate soil moisture dynamics in top surface layer. For the study, the θ in OUAT land was measured daily by 5 TM water content sensor for the duration of two years spanning from January 2021 to December 2022. Meteorological data for these 2 years are collected from a nearby weather station at OUAT and used for calculating evapotranspiration (ET) based on five different well known ET models. Soil hydraulic parameters of OUAT land were also evaluated by laboratory investigation. The evapotranspiration so calculated along with precipitation and materials properties were then assigned as the inputs in Hydrus 2D simulations. The simulated results are found to be in good agreement with field observations. It is proven by Pearson's coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE) which are found to be 0.83 and 0.84 respectively. The soil moisture simulation was the most accurate only when measured soil parameters along with atmospheric boundary involving Penman-Monteith (PM) ET model were considered as model inputs. [ABSTRACT FROM AUTHOR]

Ongoing climate change is likely to put increased selection pressures on the phenology of plants, yet for many species their abilities to respond to environmental cues are unknown. The present research focuses on using herbarium specimens to examine how 14 native plant species in Alberta have adjusted or adapted to changes in temperature and precipitation over the past century. We specifically investigate the impact of flowering-time responses and determine (1) whether herbaria collections contain sufficient evidence of these phenological responses to climate in plant species in Alberta, and (2) whether the responses are dependent on the typical moisture regime of their habitat. We compared plants from mesic and xeric habitats in terms of their phenological responses to air temperature and precipitation. In this study, the taxonomic relationships between the species were considered by selecting 14 species representing seven different angiosperm orders (one pair of species for each order). By collating data on the peak flowering date over the past century using preserved specimens, we found that on average, species from xeric habitats are more responsive to temperature, but not precipitation. This tendency might be explained by the thermal properties of mesic habitats, a finding that may lead to ways to predict the degree to which environmental cues will govern flowering. [ABSTRACT FROM AUTHOR]

In the Arctic region, microbial degradation poses a significant threat to the preservation of archaeological deposits, actively consuming irreplaceable cultural and environmental records. In this study we assess the potential effects of the last 40 years of climate change on organic archaeological deposits within the UNESCO World Heritage area Kujataa in South Greenland. We use the dynamic process-oriented model, CoupModel to simulate soil temperatures and soil moisture contents at four archaeological sites in the area. The results show that the organic deposits have experienced a substantial warming the last 40 years, which combined with decreasing soil moisture contents creates a dangerous combination that can accelerate the degradation of organic materials. Currently, there are 583 archaeological sites registered within the area. Our findings highlight that the current climatic conditions are not conducive to organic preservation. The greatest risk of degradation lies within the relatively dry continental inland areas of the study region, where all Norse Viking Age settlements are situated. However, even at the "cold" and "wet" outer coast, the combined effects of rising summer temperatures and declining soil moisture levels may already be exerting a noticeable impact. [ABSTRACT FROM AUTHOR]

Soil moisture (SM) is essential for sustaining services from Earth's critical zone, a thin-living skin spanning from the canopy to groundwater. In the Anthropocene epoch, intensive afforestation has remarkably contributed to global greening and certain service improvements, often at the cost of reduced SM. However, attributing the response of SM in deep soil to such human activities is a great challenge because of the scarcity of long-term observations. Here, we present a 37 y (1985 to 2021) analysis of SM dynamics at two scales across China's monsoon loess critical zone. Site-scale data indicate that land-use conversion from arable cropland to forest/grassland caused an 18% increase in SM deficit over 0 to 18 m depth (P < 0.01). Importantly, this SM deficit intensified over time, despite limited climate change influence. Across the Loess Plateau, SM storage in 0 to 10 m layer exhibited a significant decreasing trend from 1985 to 2021, with a turning point in 1999 when starting afforestation. Compared with SM storage before 1999, the relative contributions of climate change and afforestation to SM decline after 1999 were -8% and 108%, respectively. This emphasizes the pronounced impacts of intensifying land-use conversions as the principal catalyst of SM decline. Such a decline shifts 18% of total area into an at-risk status, mainly in the semiarid region, thereby threatening SM security. To mitigate this risk, future land management policies should acknowledge the crucial role of intensifying land-use conversions and their interplay with climate change. This is imperative to ensure SM security and sustain critical zone services. [ABSTRACT FROM AUTHOR]

Changes in climate and grazing intensity influence plant-community compositions and their functional structure. Yet, little is known about their possible interactive effects when climate change mainly has consequences during the growing season and grazing occurs off growing season (dormant season grazing). We examined the contribution of trait plasticity to the immediate responses in the functional structure of plant community due to the interplay between these two temporally disjunct drivers. We conducted a field experiment in the northern Mongolian steppe, where climate was manipulated by open-top chambers (OTCs) for two growing seasons, increasing temperature and decreasing soil moisture (i.e., increased aridity), and grazing was excluded for one dormant season between these two growing seasons. We calculated the community-weighted mean (CWM) and the functional diversity (FD) of six leaf traits. Based on a variance partitioning approach, we evaluated how much of the responses in CWM and FD to OTCs and dormant season grazing occur through plasticity. The interactive effect of OTCs and the dormant season grazing were detected only after considering the role of trait plasticity. Overall, OTCs influenced the responses in CWM more than in FD, but the effects of OTCs were much less pronounced where dormant season grazing occurred. Thus, warming (together with decreased soil moisture) and the elimination of dormant season grazing could interact to impact the functional trait structure of plant communities through trait plasticity. Climate change effects should be considered in the context of altered land use, even if temporally disjunct. [ABSTRACT FROM AUTHOR]

The increasing impact of global climate change has resulted in adversity stresses, like salt and drought, gradually becoming the main factors that limit crop growth. Hemp, which contains numerous medicinal active components and multiple bioactive functions, is widely used in the agricultural, industrial, and medical fields, hence promoting the rapid development of related industries. Arbuscular mycorrhizal fungi (AMF) can establish a symbiotic relationship with 80% of vascular plants. This symbiosis promotes host plant growth, regulates plant physiology and biochemistry, facilitates secondary metabolite synthesis, and enhances resistance to abiotic stresses. However, the effects of salt stress, drought stress, and AMF interaction in hemp are not well understood. In this study, to investigate this, we performed a study where we cultured hemp that was either inoculated or uninoculated with Funneliformis mosseae and determined changes in effective colonization rate, growth, soluble substances, photosynthesis, fluorescence, ions, and secondary metabolites by cultivating hemp under different concentrations of NaCl (0 mM, 100 mM, and 200 mM) and different soil moisture content (45%, 25%, and 15%). The results showed that salt, drought stress, or salt–drought interaction stress all inhibited colonization rate after stress, plant growth, mainly due to ion toxicity and oxidative damage. Inoculation with F. mosseae effectively alleviated plant growth inhibition under 100 mM NaCl salt stress, drought stress, and salt–drought interaction stress conditions. It also improved osmoregulation, photosynthetic properties, fluorescence properties, and ion homeostasis, and promoted the accumulation of secondary metabolites. However, under 200 mM NaCl salt stress conditions, inoculation with F. mosseae negatively affected plant physiology, biochemistry, and secondary metabolite synthesis, although it did alleviate growth inhibition. The results demonstrate that there are different effects of salt–drought interaction stress versus single stress (salt or drought stress) on plant growth physiology. In addition, we provide new insights about the positive effects of AMF on host plants under such stress conditions and the effects of AMF on plants under high salt stress. [ABSTRACT FROM AUTHOR]

Scientists widely agree that anthropogenically driven climate change significantly impacts vegetation growth, particularly in floodplain areas, by altering river flow and flood regimes. This impact will accelerate in the future, according to climate change projections. For example, in Australia, climate change has been attributed to a decrease in winter precipitation in the range of 56% to 72.9% and an increase in summer from 11% to 27%, according to different climate scenarios. This research attempts to understand vegetation responses to climate change variability at the floodplain level. Further, this study is an effort to enlighten our understanding of temporal climate change impacts under different climate scenarios. To achieve these aims, a semi-distributed hydrological model was applied at a sub-catchment level to simulate the Leaf Area Index (LAI). The model was simulated against future time series of climate data according to Global Climate Model (GCM) projections. The time series data underwent a non-parametric Mann–Kendall test to detect trends and assess the magnitude of change. To quantify the model's performance, calibration and validation were conducted against the Moderate Resolution Imaging Spectroradiometer (MODIS) LAI. The calibration and validation results show Nash–Sutcliffe efficiency (NSE) values of 0.85 and 0.78, respectively, suggesting the model's performance is very good. The modeling results reveal that the rainfall pattern fluctuates under climate projections within the study site, in which vegetation tends to be more vibrant during the warmer seasons. Moreover, the modeling results highlighted increases in the average projected future winter temperatures, which can help vegetation growth during winter. The results of this study may be employed for sustainable floodplain management, restoration, land-use planning, and policymaking, and help floodplain communities better prepare for and respond to changing flood patterns and related challenges under a future changing climate. [ABSTRACT FROM AUTHOR]

[Objective] The aims of this study are to analyze the spatiotemporal differentiation and variation of soil moisture in the Mongolian Plateau, and to quantify the influence of key driving factors, so as to provide a theoretical basis for regional ecological restoration and sustainable ecosystem development. [Methods] Based on the ERA5 soil moisture data, the spatial differentiation and changes of soil moisture at the depth of 0—289 cm in the Mongolian Plateau from 2000 to 2020 were revealed, and the impacts of different environmental factors such as meteorology, normalized difference vegetation index (NDVI), terrestrial water storage anomaly (TWSA), soil texture, and topography were further quantified. [Results] (1) From 2000 to 2020, soil moisture in the Mongolian Plateau displayed a distribution characteristic of high level in the northeast and low level in the southwest. From shallow to deep layers, the soil moisture presented a change trend of no significant increase (0—28 cm), no significant decrease (28—100 cm) and significant decrease (100—289 cm) . (2) There were 58.5%, 76.7%, 91.3%, and 98.8% of the regions with Hurst index greater than 0.5. The change trend of soil moisture in most regions in the future will be the same as in the past. The drying of soil moisture in the northwestern Mongolian Plateau and central Inner Mongolia may further aggravate. (3) Temperature, TWSA, precipitation, and NDVI were the dominant environmental factors affecting the spatial distribution of soil moisture. Most of the factor interactions showed a bi-factor enhancement effect, and the spatial differentiation of soil moisture in the Mongolian Plateau was the result of the joint action of multiple factors. (4) The changes in surface and subsurface soil moisture were mainly positively affected by precipitation, and the dominant control areas accounted for 98.7% and 94.8% of the total vegetated area of the plateau, respectively. The main control areas of precipitation and TWSA on soil moisture at the layer of 28—100 cm concentrated in areas covered by forestland and grassland, with the dominant area accounting for 38.7% and 38.8%, respectively. The decrease in TWSA was the main driving force leading to the drying of soil moisture in the layer of 100—289 cm, with the main dominant area accounting for 58.6%. The increase in water consumption by vegetation and the increase in temperature dominantly controlled the changes in soil moisture in layer of 100—289 cm in 16.2% and 14.8% of the plateau, respectively. [Conclusion] The spatial and temporal differentiation and change patterns of soil moisture are obvious, and the main driving forces of soil moisture at each depth are different. This is of great significance to the ecological restoration of the Mongolian Plateau and the sustainable development of the ecosystem. In the future, the impact of human activities on it should be analyzed in depth. [ABSTRACT FROM AUTHOR]

Grasslands, which encompass 40% of terrestrial ecosystems, hold global significance for food production, carbon storage and other ecosystem services. However, grasslands across the biosphere are becoming increasingly exposed to both wet and dry precipitation extremes resulting from climate change.Therefore, understanding how grasslands will respond to precipitation extremes is a pressing issue for managing changes to biodiversity and ecosystem service provision.Here, we use experimental manipulations of precipitation (50% increase and 50% decrease in growing‐season precipitation) over 6 years to investigate the stability and resistance of both productivity and community diversity in a calcareous grassland community.We found that decreased growing‐season precipitation led to reductions in mean productivity (25% decrease in peak above‐ground biomass) and its temporal stability (54% increase in the coefficient of variation of biomass across years). Productivity losses were more pronounced for graminoids and legumes, but this was not reflected in species per cent cover. Community composition was resistant to the precipitation manipulations, with no clear differences in overall community compositional turnover, dissimilarity or biodiversity indices. There was also no detectible effect of increased precipitation on productivity or community composition, which may indicate a lack of efficacy of the irrigation treatment in increasing soil moisture. Finally, the precipitation manipulations had no effect on temporal trends of community change, with an overall increase in richness and shift in grassland community composition across the study period independent of treatment.Synthesis. While the diversity and composition of this calcareous grassland was resistant to precipitation extremes (at least in the short term), sustained reductions in growing‐season precipitation reduced productivity and its temporal stability, particularly for graminoids and legumes. Therefore, we highlight that different properties of grasslands can vary in their responses to changes in precipitation. [ABSTRACT FROM AUTHOR]

The evolutionary dynamics of tree species are influenced by their specific climatic environments, and their ability to persist is determined by adaptive strategies such as broad climate tolerance, phenotypic plasticity or genetic differentiation. Biogeographical predictions indicate that populations located at the edges of their ranges are more likely to experience heightened vulnerability to climatic fluctuations due to approaching tolerance limits. However, if local phenotypic acclimation or genetic adaptation has taken place, trees near the edge of their range could demonstrate comparable sensitivity to freeze and drought as the rest of the sampled population. Nevertheless, there remains uncertainty regarding the extent of developmental and evolutionary adjustments in climate sensitivity across the entire ranges of many tree species.Here, we document the biogeography of tree growth sensitivity to freeze and soil water and vapour pressure deficits during 1950–2018 using an extensive multi‐species tree‐ring dataset of 35,784 trees at 4535 sites covering boreal, temperate conifer and temperate deciduous forests of Canada. We quantify the relationships between tree radial growth increment and seasonal climate variables and explore factors driving the observed patterns of annual growth and climate sensitivity such as species, regional climate and local site conditions, and tree age and size.Freeze and drought had widespread impacts on tree growth that were contingent on the presence of focal species in interaction with tree size. An indirect growth thermal limitation towards cold/wet edges, occurring through the site moisture conditions, was observed in seven widespread species (e.g. Picea glauca, Picea mariana and Larix laricina). Moreover, six species had negative drought impacts more strongly expressed towards their warm/dry edges (e.g. Abies balsamea, Betula papyrifera and Pseudotsuga menziesii). However, widespread Picea, Pinus and Populus species showed no indication of increased sensitivity to soil water conditions at these edges.Synthesis. Our findings support the idea of evolutionary or acclimatization adjustments in the development of populations in response to long‐term climate conditions experienced in their respective locations. This underscores the importance of incorporating phenotypic and genomic data into future analyses of climate change impacts, which would enhance our ability to predict potential ecological shifts. [ABSTRACT FROM AUTHOR]

Climate change has been intensifying soil drying and rewetting cycles, which can alter the soil microbiome structure and activity. Here we hypothesized that a soil drying-rewetting cycle enhances biodegradation and, hence, decreases the effectiveness of nitrification inhibitors (NIs). The effectiveness of DMPP (3,4-Dimethylpyrazole phosphate) and MP + TZ (3-Methylpyrazol and Triazol) was evaluated in 60-day incubation studies under a drying and rewetting cycle relative to constant low and high soil moisture conditions (40% and 80% water-holding capacity, WHC, respectively) in two different textured soils. The measurements included (i) daily and cumulative N2O-N emissions, (ii) soil NH4+-N and NO3−-N concentrations, and (iii) the composition of bacterial soil communities. Application of DMPP and MP + TZ reduced the overall N2O-N emissions under drying-rewetting (-45%), as well as under 40% WHC (-39%) and 80% WHC (-25%). DMPP retarded nitrification and decreased N2O-N release from the sandy and silt loam soils, while MP + TZ mitigated N2O-N production only from the silt loam soil. Unexpectedly, between days 30 and 60, N2O-N emissions from NI-treated soils increased by up to fivefold relative to the No-NI treatment in the silt loam soil at 80% WHC. Likewise, the relative abundance of the studied nitrifying bacteria indicated that the NIs had only short-term effectiveness in the silt loam soil. These results suggested that DMPP and MP + TZ might trigger high N2O-N release from fine-textured soil with constant high moisture after this short-term inhibitory effect. In conclusion, DMPP and MP + TZ effectively reduce N2O-N emissions under soil drying and rewetting. [ABSTRACT FROM AUTHOR]

Climate change impacts drive warmer winters, reduced snowfall, and forest fires. In 2020, a wildfire scorched about 1508 hectares of black pine (Pinus nigra Arnold) forests in Türkiye. Whether the combined effects of lack of snow and forest fires significantly alter winter soil respiration (Rs) and soil temperature remains poorly understood. A field experiment was conducted in the postfire and undisturbed black pine forests during the winter to quantify Rs rates as affected by lack of snow and forest fire. We applied four treatments: snow‐exclusion postfire (SEPF), snow postfire (SPF), snow‐exclusion‐undisturbed forest (SEUF), and snow undisturbed forest (SUF). The SEPF exhibited the significantly lowest mean Rs rates (0.71 μmol m−2 s−1) compared to the SPF (1.02 μmol m−2 s−1), SEUF (1.44 μmol m−2 s−1), and SUF (1.48 μmol m−2 s−1). The Rs also showed significant variations with time (p <.0001). However, treatments and time revealed no statistically significant interaction effects (p =.6801). Total winter Rs (January–March) ranged from 4.47 to 4.59 Mt CO2 ha−1 in the undisturbed forest and 2.20 to 3.16 Mt CO2 ha−2 in the postfire site. The Rs showed a significantly positive relationship (p <.0001) with the soil (0.59) and air (0.46) temperatures and a significantly negative relationship (p =.0017) with the soil moisture (−0.20) at the 5 cm depth. In contrast, the Rs indicated a negative but not statistically significant relationship (p =.0932) with the soil moisture (−0.16) at the 10 cm soil depth. The combined effects of lack of snow and forest fire significantly decreased Rs, thus conserving the soil's organic carbon stocks and reducing the CO2 contribution to the atmosphere. In contrast, a warmer winter significantly increased Rs rates in the undisturbed forest, suggesting an acceleration of soil organic carbon losses and providing positive feedback to climate change. [ABSTRACT FROM AUTHOR]

The high-resolution temporal records (1738–2018 CE) of the dendrochronological analysis on Cedrus deodara from Uttarakhand and Himachal Pradesh in the western Himalayan region were generated. An analysis of the association between the Normalized Difference Vegetation Index (NDVI) and tree-ring radial growth indicated a significant positive relationship from April to July. The association between tree rings and other hydroclimatic variables was used to further evaluate this relationship. Based on the observation, mean April–July NDVI variability since 1790 CE was reconstructed based on the regional tree-ring chronology. Comparisons of the reconstructed NDVI with gridded precipitation, drought records, and proxy-based hydroclimatic reconstructions revealed a consistent agreement over a large spatial domain extending beyond the study region. We observed a correlation between the region's NDVI browning (reduction) and past droughts and famines. Comparison has been made to the regional proxy-based hydroclimatic reconstruction and stable oxygen isotope datasets with the present NDVI reconstruction. This revealed the commonalities in the regional hydroclimatic scenario recorded in these data sets over the last few centuries. This first tree-ring-based NDVI reconstruction from the western Himalayas infers regional climate-vegetation dynamics during the past two centuries. This reconstruction provides valuable input for modeling vegetation dynamics for predicting vegetation changes due to climate variations in the western Himalaya. [ABSTRACT FROM AUTHOR]

Simple Summary: The Platycladus orientalis is a coniferous gymnosperm tree species widely distributed in China and the fFar east of Russia. It has been widely introduced and cultivated in East and South Asia. Plant abscisic acid increases and affects stomatal behavior during soil drought, and prolonged drought-induced stomatal closure definitely affects the soluble sugar content of plants. We found significant correlations between gas exchange and abscisic acid content, as well as the soluble sugar content of Platycladus orientalis under different moisture conditions, as a result of increased drought stress in Platycladus orientalis due to ongoing global climate change. This helps us to reveal the mechanism of plant adaptation to drought–rehydration under different drought treatments. To uncover the internal mechanisms of various drought stress intensities affecting the soluble sugar content in organs and its regulation by endogenous abscisic acid (ABA), we selected the saplings of Platycladus orientalis, a typical tree species in the Beijing area, as our research subject. We investigated the correlation between tree soluble sugars and endogenous ABA in the organs (comprised of leaf, branch, stem, coarse root, and fine root) under two water treatments. One water treatment was defined as T1, which stopped watering until the potted soil volumetric water content (SWC) reached the wilting coefficient and then rewatered the sapling. The other water treatment, named T2, replenished 95% of the total water loss of one potted sapling every day and irrigated the above-mentioned sapling after its SWC reached the wilt coefficients. The results revealed that (1) the photosynthetic physiological parameters of P. orientalis were significantly reduced (p < 0.05) under fast and slow drought processes. The photosynthetic physiological parameters of P. orientalis in the fast drought–rehydration treatment group recovered faster relative to the slow drought–rehydration treatment group. (2) The fast and slow drought treatments significantly (p < 0.05) increased the ABA and soluble sugar contents in all organs. The roots of the P. orientalis exhibited higher sensitivity in ABA and soluble sugar content to changes in soil moisture dynamics compared to other organs. (3) ABA and soluble sugar content of P. orientalis showed a significant positive correlation (p < 0.05) under fast and slow drought conditions. During the rehydration stage, the two were significantly correlated in the T2 treatment (p < 0.05). In summary, soil drought rhythms significantly affected the photosynthetic parameters, organ ABA, and soluble sugar content of P. orientalis. This study elucidates the adaptive mechanisms of P. orientalis plants to drought and rehydration under the above-mentioned two water drought treatments, offering theoretical insights for selecting and cultivating drought-tolerant tree species. [ABSTRACT FROM AUTHOR]

Semi-arid regions are strongly dependent on the rainfall regime. Yet season identification is still ambiguous and clear definitions are lacking regarding which variables and criteria should be used. The objective of this work is to establish a method for hydrological season partitioning in the semi-arid Caatinga biome in northeastern Brazil considering precipitation, soil moisture and vegetation. The following four periods were employed for this purpose: (i) dry–rainy transition, (ii) rainy season, (iii) rainy–dry transition and (iv) dry season. The method was applied to the Aiuaba experimental basin (AEB) from 2003 to 2022. We observed a large inter-annual variability in the duration of seasons and a tendency for the rainy–dry transition season to increase, facts that may indicate changes in the hydrological regime of the region. This novel combination of precipitation, soil moisture, and vegetation data for identification of hydrological seasons within the Caatinga biome allows a detailed seasonal hydrological behaviour analysis. [ABSTRACT FROM AUTHOR]

As a region susceptible to the impacts of climate change, evaluating the temporal and spatial variations in ecological environment quality (EEQ) and potential influencing factors is crucial for ensuring the ecological security of the Tibetan Plateau. This study utilized the Google Earth Engine (GEE) platform to construct a Remote Sensing-based Ecological Index (RSEI) and examined the temporal and spatial dynamics of the Tibetan Plateau's EEQ from 2000 to 2022. The findings revealed that the RSEI of the Tibetan Plateau predominantly exhibited a slight degradation trend from 2000 to 2022, with a multi-year average of 0.404. Utilizing SHAP (Shapley Additive Explanation) to interpret XGBoost (eXtreme Gradient Boosting), the study identified that natural factors as the primary influencers on the RSEI of the Tibetan Plateau, with temperature, soil moisture, and precipitation variables exhibiting higher SHAP values, indicating their substantial contributions. The interaction between temperature and precipitation showed a positive effect on RSEI, with the SHAP interaction value increasing with rising precipitation. The methodology and results of this study could provide insights for a comprehensive understanding and monitoring of the dynamic evolution of EEQ on the Tibetan Plateau amidst the context of climate change. [ABSTRACT FROM AUTHOR]

Species-specific tree traits substantially impact precipitation partitioning, soil infiltration, retention, and overall water management. With the changing climate, the evidence of drought-induced tree mortality is increasing, indicating the need for a shift to more resilient species. Therefore, the knowledge of tree species' effect on soil–water management is needed. We used a total of 54 stations for monitoring the soil moisture regimes of silt loam soil in Central Bohemia under three common and different tree species (spruce, larch, and beech). For the dry and warm part of the year 2022, the soil moisture in winter and early spring was significantly lowered by high canopy interception and gradually depleted by early spring transpiration of evergreen spruce, where mean values were more than 15% lower than for beech. Since March, the soil moisture under spruce was already below the limit of easily available water. In contrast, the deciduous beech and larch did not show a significant decrease until the foliage emergence in early May. The beech stands showed the highest soil moisture levels, which we attributed to a more effective water recharge mechanism induced by its structural traits. This adaptive strategy is vital as soil–water storage is critical for coping with climate change. In general, the results show a distinct advantage in the water recharge ability of deciduous trees and that the selection of tree species can distinctly affect soil moisture conditions, especially during drought periods in areas characterized by tight hydrological balance. [ABSTRACT FROM AUTHOR]

Global climate change is expected to increase the frequency and intensity of extreme droughts. Researching tree growth responses to drought helps assess the potential of forest adaptation and ecological stability under changing climate conditions. Here, we investigated tree growth resilience components (resistance, recovery, and resilience) to extreme drought events of two mainly distributed species, Pinus tabulaeformis and Picea wilsonii, on the Gannan Plateau, the Eastern Tibetan Plateau. Tree-ring width data from 510 trees at 20 plots along the elevation gradients were employed to analyze the tree resilience components at the individual tree level. The results showed that P. tabulaeformis had a lower growth resistance and a higher recovery capacity to drought than P. wilsonii, which might be related to the different strategies for combating drought of the two species. In addition, the tree growth response of P. tabulaeformis to drought changed significantly along the elevation gradient due to its higher drought sensitivity than that of P. wilsonii. Overall, the long-term correlation between tree growth and drought index, tree size, and soil water content had implications for tree growth resistance, recovery, and resilience. Given the observed differences in tree growth resistance to drought among different species and environmental conditions, a well-thought-out and tailored strategy would better support forest management on the Gannan Plateau. [ABSTRACT FROM AUTHOR]

Agricultural flash droughts are high-impact phenomena, characterized by rapid soil moisture dry down. The ensuing dry conditions can persist for weeks to months, with detrimental effects on natural ecosystems and crop cultivation. Increases in the frequency of these rare events in a future warmer climate would have significant societal impact. This study uses an ensemble of 10 Coupled Model Intercomparison Project (CMIP) models to investigate the projected change in agricultural flash drought during the 21st century. Comparison across geographical regions and climatic zones indicates that individual events are preceded by anomalously low relative humidity and precipitation, with long-term trends governed by changes in temperature, relative humidity, and soil moisture. As a result of these processes, the frequency of both upper-level and root-zone flash drought is projected to more than double in the mid- and high latitudes over the 21st century, with hot spots developing in the temperate regions of Europe, and humid regions of South America, Europe, and southern Africa. [ABSTRACT FROM AUTHOR]

We demonstrate an indirect, rather than direct, role of quasi-resonant amplification of planetary waves in a summer weather extreme. We find that there was an interplay between a persistent, amplified large-scale atmospheric circulation state and soil moisture feedbacks as a precursor for the June 2021 Pacific Northwest "Heat Dome" event. An extended resonant planetary wave configuration prior to the event created an antecedent soil moisture deficit that amplified lower atmospheric warming through strong nonlinear soil moisture feedbacks, favoring this unprecedented heat event. [ABSTRACT FROM AUTHOR]

We review results from field experiments that simulate drought, an ecologically impactful global change threat that is predicted to increase in magnitude, extent, duration and frequency. Our goal is to address, from primarily an ecosystem perspective, the questions 'What have we learned from drought experiments?' and 'Where do we go from here?'.Drought experiments are among the most numerous climate change manipulations and have been deployed across a wide range of biomes, although most are conducted in short‐statured, water‐limited ecosystems. Collectively, these experiments have enabled ecologists to quantify the negative responses to drought that occur for most aspects of ecosystem structure and function. Multiple meta‐analyses of responses have also enabled comparisons of relative effect sizes of drought across hundreds of sites, particularly for carbon cycle metrics. Overall, drought experiments have provided strong evidence that ecosystem sensitivity to drought increases with aridity, but that plant traits associated with aridity are not necessarily predictive of drought resistance. There is also intriguing evidence that as drought magnitude or duration increases to extreme levels, plant strategies may shift from drought tolerance to drought escape/avoidance.We highlight three areas where more drought experiments are needed to advance our understanding. First, because drought is intensifying in multiple ways, experiments are needed that address alterations in drought magnitude versus duration, timing and/or frequency (individually and interactively). Second, drivers of drought may be shifting—from precipitation deficits to rising atmospheric demand for water—and disentangling how ecosystems respond to changes in hydrological 'supply versus demand' is critical for understanding drought impacts in the future. Finally, more attention should be focussed on post‐drought recovery periods since legacies of drought can affect ecosystem functioning much longer than the drought itself.We conclude with a call for a fundamental shift in the focus of drought experiments from those designed primarily as 'response experiments', quantifying the magnitude of change in ecosystem structure and function, to more 'mechanistic experiments'—those that explicitly manipulate ecological processes or attributes thought to underpin drought responses. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The ability of plants to adjust to the adverse effects of climate change is important for their survival and for their contribution to the global carbon cycle. This is particularly true in the Mediterranean region, which is among the regions that are most vulnerable to climate change. Here, we carried out a 2-year comparative ecophysiological study of ecosystem function in two similar Eastern Mediterranean forests of the same tree species (Pinus halepensis Mill.) under mild (Sani, Greece) and extreme (Yatir, Israel) climatic conditions. The partial effects of key environmental variables, including radiation, vapor pressure deficit, air temperature and soil moisture (R g, D , T and soil water content (SWC), respectively), on the ecosystems' CO2 and water vapor fluxes were estimated using generalized additive models (GAMs). The results showed a large adjustment between sites in the seasonal patterns of both carbon and water fluxes and in the time and duration of the optimal period (defined here as the time when fluxes were within 85% of the seasonal maximum). The GAM analysis indicated that the main factor influencing the seasonal patterns was SWC, while T and D had significant but milder effects. During the respective optimal periods, the two ecosystems showed strong similarities in the fluxes' responses to the measured environmental variables, indicating similarity in their underlying physiological characteristics. The results indicate that Aleppo pine forests have a strong phenotypic adjustment potential to cope with increasing environmental stresses. This, in turn, will help their survival and their continued contribution to the terrestrial carbon sink in the face of climate change in this region. [ABSTRACT FROM AUTHOR]

Question: Climate change intensifies global and regional water cycles, leading to changes in both the magnitude and timing of precipitation. Precipitation use efficiency (PUE) plays a crucial role in measuring the response of above‐ground net primary productivity (ANPP) to precipitation changes. However, little is known about how changes in precipitation during different periods affect PUE. Methods: Using a manipulation precipitation experiment in a semi‐arid steppe, we simulated a 60% increase and decrease in precipitation during the early (April–June), late (July–September), and entire (April–September) growing seasons across 2015–2021 to examine the effects of changes in precipitation timing on PUE. Results: The results showed that: (1) decreased precipitation in the late growing season (DLP) and whole growing season (DWP) stimulated PUE by an average of 0.14 and 0.12 g m−2 mm−1 yr−1 respectively, whereas increased precipitation in the late growing season (ILP) and whole growing season (IWP) suppressed PUE by an average of 0.11 and 0.09 g m−2 mm−1 yr−1 respectively. By contrast, neither decreased nor increased precipitation in the early growing season affected PUE; (2) the increased PUE under DLP was primarily attributed to the increase of PUE in grass (GR) and annuals and biennials (AB), whereas the elevation of PUE under DWP was mainly due to an increase of PUE in AB. By contrast, the reduction of PUE under ILP was mainly caused by a decline of PUE in GR; (3) changes in evapotranspiration and leaf dry matter content (LDMC) explained the variation of PUE in AB while changes of PUE in GR was mainly due to the alteration of soil water content and LDMC. Conclusions: These results suggest that precipitation during the late growing season has a crucial influence on PUE, highlighting the importance of evapotranspiration and LDMC in regulating ecosystem productivity in the semi‐arid steppe. [ABSTRACT FROM AUTHOR]

Projections of West African Monsoon (WAM) precipitation are uncertain. To address this, an improved understanding of the mechanisms driving WAM precipitation change is needed to shed light on inter-model differences and aid model development. The full forcing of increased CO2 can be decomposed into different components such as the impact of ocean warming, or the direct radiative effect of increased CO2. This paper investigates such a decomposition, analysing the effect of a uniform 4K ocean warming whilst keeping atmospheric CO2 concentrations constant. The analysis highlights several mechanisms acting to decrease WAM precipitation over a range of timescales, from days after the abrupt ocean warming, to the long-term equilibrium response. The initial decrease in WAM precipitation is caused by warming and enhanced convection over the ocean, stabilising the atmosphere inland and disrupting the monsoon inflow at low levels. Later in the response (after about 5 days), the WAM precipitation is reduced through a strengthening of the shallow circulation over West Africa, associated with changes in the large-scale temperature gradients and a local warming of the atmosphere related to a soil moisture feedback mechanism over the Sahel. Finally, from around 20 days after the SST increase, the WAM precipitation is also reduced through changes in specific humidity gradients that lead to increased potency of dry air advection into the monsoon rainband. The analysis concludes by demonstrating that the processes affecting precipitation in the early stages of the response are also relevant to the long-term equilibrium response. [ABSTRACT FROM AUTHOR]

Climate change and human activities lead to freshwater shortage, soil salinization, and food security crises in arable land. To explore the natural and irrigation factors on soil water and salt movement, this study quantitatively analyzed the dynamic characteristics of soil water and salt movement under precipitation, groundwater irrigation, and brackish water irrigation conditions for the next 30 years using Hydrus-1D model-based parameters obtained from the winter wheat–summer maize rotation experiments in the Yellow River Irrigation District. The results showed that precipitation was the key factor of climate change affecting soil water and salt migration, especially in the 0–20 cm soil layer. Under both SSP585 and SSP245 climate scenarios, rainfall in normal and wet years promoted salt leaching up to 1 m below the surface soil. But in dry years, salt washing treatment was required for the tillage layer to prevent salt accumulation. The higher the groundwater level was, the higher the soil water and salt content was in the 0–100 cm soil layer. In this soil layer, a 2 m groundwater level contributed 30% to wheat water needs, while a 3 m groundwater level contributed 18%, and no significant contribution was observed for a 4 m groundwater level. The salinity of the soil profile showed an overall increasing trend with irrigation using 1–3 g/L brackish water for 30 years. However, the salinity in the 0–100 cm soil layer was below the salt tolerance threshold of winter wheat and summer maize with salts accumulated in the 1–2 m soil layer. Considering the salinization of the root zone and crop water needs, it is recommended that the safe groundwater level for brackish water irrigation should be 3 m in the study region. This study provides scientific reference for groundwater–farmland ecosystems to utilize brackish water and treat saline–alkali lands. [ABSTRACT FROM AUTHOR]

Microbes inhabiting deep soil layers are known to be different from their counterpart in topsoil yet remain under investigation in terms of their structure, function, and how their diversity is shaped. The microbiome of deep soils (>1 m) is expected to be relatively stable and highly independent from climatic conditions. Much less is known, however, on how these microbial communities vary along climate gradients. Here, we used amplicon sequencing to investigate bacteria, archaea, and fungi along fifteen 18‐m depth profiles at 20–50‐cm intervals across contrasting aridity conditions in semi‐arid forest ecosystems of China's Loess Plateau. Our results showed that bacterial and fungal α diversity and bacterial and archaeal community similarity declined dramatically in topsoil and remained relatively stable in deep soil. Nevertheless, deep soil microbiome still showed the functional potential of N cycling, plant‐derived organic matter degradation, resource exchange, and water coordination. The deep soil microbiome had closer taxa–taxa and bacteria–fungi associations and more influence of dispersal limitation than topsoil microbiome. Geographic distance was more influential in deep soil bacteria and archaea than in topsoil. We further showed that aridity was negatively correlated with deep‐soil archaeal and fungal richness, archaeal community similarity, relative abundance of plant saprotroph, and bacteria–fungi associations, but increased the relative abundance of aerobic ammonia oxidation, manganese oxidation, and arbuscular mycorrhizal in the deep soils. Root depth, complexity, soil volumetric moisture, and clay play bridging roles in the indirect effects of aridity on microbes in deep soils. Our work indicates that, even microbial communities and nutrient cycling in deep soil are susceptible to changes in water availability, with consequences for understanding the sustainability of dryland ecosystems and the whole‐soil in response to aridification. Moreover, we propose that neglecting soil depth may underestimate the role of soil moisture in dryland ecosystems under future climate scenarios. [ABSTRACT FROM AUTHOR]

Aim: Earth observation‐based estimates of land–atmosphere exchange of carbon are essential for understanding the response of the terrestrial biosphere to climatic change and other anthropogenic forcing. Temperature, soil water content and gross primary production are the main drivers of ecosystem respiration (Reco), and the main aims of this study are to develop an Reco model driven by long‐term global‐scale Earth observations and to study Reco spatiotemporal dynamics 1982–2015. Location: Global scale. Time Period: 1982–2015. Major Taxa Studied: Terrestrial ecosystems. Methods: We parameterized and applied a global Reco model for 1982–2015 using novel Earth observation‐based data. We studied the relationships between Reco measured at field sites globally and land surface temperature, gross primary production and soil water content. Trends 1982–2015 were quantified, and the contributions from terrestrial regions to the spatiotemporal variability were evaluated. Results: The Reco model (LGS‐Reco) captured the between‐site and intra‐ and interannual variability in field‐observed Reco and soil respiration well in comparison with other Earth observation‐based products. The global annual Reco was on average 105.6 ± 2.3 Pg C for 1982–2015, which is close to 105 Pg C according to residuals of the carbon exchange processes within the global carbon budgets. The trend in global terrestrial Reco 1982–2015 was 0.19 ± 0.02 Pg C y−1, with the strongest positive trends found in cropland areas, whereas negative trends were primarily observed for savannah/shrublands of Southern Africa and South America. Trends were especially strong during the eighties and nineties, but substantially smaller 1998–2015. Main Conclusions: The LGS‐Reco model revealed a substantial increase in global Reco during recent decades. However, the growth rates of global Reco were slower during 1998–2015, partially explaining the reduced growth rates of atmospheric CO2 during this period. The LGR‐Reco product may be an essential source for studying carbon sources and sinks and functioning of the Earth system. [ABSTRACT FROM AUTHOR]

The interplay between metal contamination and climate change may exacerbate the negative impact on the soil microbiome and, consequently, on soil health and ecosystem services. We assessed the response of the microbial community of a heavy metal-contaminated soil when exposed to short-term (48 h) variations in air temperature, soil humidity or ultraviolet (UV) radiation in the absence and presence of Enchytraeus crypticus (soil invertebrate). Each of the climate scenarios simulated significantly altered at least one of the microbial parameters measured. Irrespective of the presence or absence of invertebrates, the effects were particularly marked upon exposure to increased air temperature and alterations in soil moisture levels (drought and flood scenarios). The observed effects can be partly explained by significant alterations in soil properties such as pH, dissolved organic carbon, and water-extractable heavy metals, which were observed for all scenarios in comparison to standard conditions. The occurrence of invertebrates mitigated some of the impacts observed on the soil microbial community, particularly in bacterial abundance, richness, diversity, and metabolic activity. Our findings emphasize the importance of considering the interplay between climate change, anthropogenic pressures, and soil biotic components to assess the impact of climate change on terrestrial ecosystems and to develop and implement effective management strategies. [ABSTRACT FROM AUTHOR]

Characterizing soil salinity at the regional scale remains challenging despite decades of effort in soil mapping. Using satellite remote sensing, an effort has been made to identify the coastal saline soils in India. The study made use of the OLI sensor of the Landsat-8 satellite. The images were downloaded from the USGS EarthExplorer website. For multi-temporal studies, absolute radiometric calibration was done to minimize the impacts of changing atmospheric conditions, solar inclination and sensor view angle. Images were categorized using unsupervised classification, while a ground survey and Google Earth data were used for ground truthing. Three indices, namely normalized difference vegetation index (NDVI), salinity index (SI), and canopy response salinity index (CRSI), were used to identify soil salinity regions. For testing the vegetation index with soil salinity, 192 georeferenced soil samples from the Indian Sundarbans were collected. A relationship was developed between NDVI, SI and square of CRSI (CRSISQR) with ECe (electrical conductivity of saturation paste extract) and EC1:2 (1: 2; soil: water). For the coastal region, soils with CRSISQR < 0.16 were considered to be influenced by salinity since the relationship between ECe and CRSISQR had a maximum R² (0.50). It has been estimated that India has 12.94 lakh ha of saline soil within arable lands in all the coastal districts, and Gujarat (5.28 lakh ha), West Bengal (5.08 lakh ha), and Andhra Pradesh (1.06 lakh ha) were identified as the top three-salinity affected coastal states in the country. [ABSTRACT FROM AUTHOR]

The paper presents the study of bread wheat's chlorophyll content and grain yield traits under changing environmental conditions -- optimal water supply and simulated water-deficit conditions. Selecting 15 wheat cultivars from different regions (Russia, Kazakhstan, Kyrgyzstan, Tajikistan, Turkey, and CIMMYT) based on economically valuable characteristics became the specimens for the presented study that evaluated the SPAD indicators in correlation with the grain yield in bread wheat and determined the vital role of genotypes, environments, and genotype by environment interaction effects. The relationship between chlorophyll content and yield parameters under different growing conditions was also well-defined. The results revealed that ecosystems had more influence on the chlorophyll content than the wheat genotypes. Several wheat cultivars with soil moisture tolerance have gained identification, along with the correlation coefficient between chlorophyll content and grain yield under varied environmental conditions of water supply. The study validated the role of genotypes and environments in the manifestation of responses to stress conditions. [ABSTRACT FROM AUTHOR]

The impact of global climate change is a challenge to the sustainability of many ecosystems, including soil systems. However, the performance of soil properties under future climate was rarely assessed. Therefore, this study was carried out to evaluate selected soil processes under climate change using an agri-environmental modeling approach to Sri Lanka. The Agricultural Production Systems Simulator (APSIM) model was used to simulate soil and plant-related processes using recent past (1990–2019) and future (2041–2070) climates. Future climate data were obtained for a regional climate model (RCM) under representative concentrations pathway 4.5 scenarios. Rainfalls are going to be decreased in all the tested locations under future climate scenarios while the maximum temperature showcased rises. According to simulated results, the average yield reduction under climate change was 7.4%. The simulated nitrogen content in the storage organs of paddy declined in the locations (by 6.4–25.5%) as a reason for climate change. In general, extractable soil water relative to the permanent wilting point (total available water), infiltration, and biomass carbon lost to the atmosphere decreased while soil temperature increased in the future climate. This modeling approach provides a primary-level prediction of soil dynamics under climate change, which needs to be tested using fieldwork. [ABSTRACT FROM AUTHOR]

Aims: Silicon (Si) is an essential element for siliceous organisms, including macrophytes, phytoplankton, and diatoms. Coastal wetlands are critical for bridging the river-estuary-ocean continuum to drive the biogeochemical Si cycles. However, it remains unclear about the contents and distribution patterns of bioavailable Si in soils under various scenarios, and their environmental controls in coastal wetlands. Methods: We conducted a nationwide sampling campaign across ca. 5000 km of coastal wetlands, covering temperate, subtropical, and tropical climates in China, and quantified plant available Si (ASi) using calcium chloride extractable Si (Si-CaCl2). Results: S. alterniflora invasion did not significantly influence ASi content. In contrast, ASi content in the subtropical zone was higher than in the both temperate (medium) and tropical zones (lowest). ASi content was significantly positively correlated with nutrients (i.e., soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP)), soil water content (SWC), clay and silt contents, but negatively with soil bulk density (BD) and sand content. ASi content, in detail, increased with increasing pH (pH < 7) but decreased with increasing pH (pH > 7), showing a quadratic function relationship. Conclusions: ASi in coastal wetlands was predominately directly influenced by pH, particle size, and nutrients of coastal soil, while vegetation compositions and plant-derived lignin (Λ8) inputs illustrated a minor effect on ASi patterns. Mean annual temperature (MAT) and precipitation (MAP) indirectly regulated ASi content via affecting soil geochemistry and nutrients distribution. Taken together, ASi distribution are mostly controlled by primary pedogenesis and specific weathering processes in China's coastal wetlands. [ABSTRACT FROM AUTHOR]

The paper presents a physically based mathematical model of the key hydrophysical processes of runoff formation at a catchment point over a long-term period. The model describes the freezing and thawing of soil, the formation and melting of the snow cover, the migration of moisture to the freezing front and the infiltration of rain and melt moisture, evaporation from snow, soil cover, vegetation, and water surface. Average daily values of meteorological parameters are used as initial information for mathematical modeling. The relevance of the study is caused by a need to reveal the main links between the processes of vertical heat and moisture exchange in soil and the environmental factors that determine their climate-driven nature. Using observational data from water balance stations, numerical experiments and an analysis of the influence of long-term variability of the key meteorological factors on evaporation from the land and water surface and on vertical moisture flows in soil were carried out. [ABSTRACT FROM AUTHOR]

Elevated temperature and frequent drought events under global climate change may seriously affect soil respiration. However, the underlying mechanism of the effects of warming and drought on soil respiration is not fully understood in the context of the Loess Plateau. This study examined the response of soil respiration (Rs) to multiple factors, including warming (W), drought (P), and their interaction (WP), in the semi-arid grassland of the Loess Plateau in Northwest China. The research period was from May to November 2022, with an open-top heating box used for warming and a rain shelter used for drought. The results showed the following: (1) Rs ranged from 1.67 μmol m−2 s−1 to 4.77 μmol m−2 s−1, with an average of 3.36 ± 0.07 μmol m−2 s−1. The cumulative soil carbon flux ranged from 500.97 g C·m−2 to 566.97 g C·m−2, and the average cumulative soil respiration was 535.28 ± 35.44 g C·m−2. (2) Warming increased Rs by 5.04 ± 3.11%, but drought inhibited Rs by 3.40 ± 3.14%, and the interaction between warming and drought significantly reduced soil respiration by 11.27 ± 3.89%. (3) The content of particulate organic carbon (POC), dissolved organic carbon (DOC), soil organic carbon (SOC), and readily oxidized carbon (ROC) decreased with the increased soil depth. ROC after W and WP treatments was significantly higher than that of the control, and POC after P treatment was significantly higher than CK (p < 0.05). (4) The seasonal variation of soil respiration was positively correlated with soil temperature, soil water content, plant height, and leaf area index (p < 0.05), but the response rules differed during different regeneration periods. Soil water content; soil water content and leaf area index; and soil water content, soil temperature, and leaf area index were the factors that regulated the variation in soil respiration in the first, second, and third regeneration periods, respectively. These results clearly showed the limiting effect of drought stress on the coupling between temperature and soil respiration, especially in semi-arid regions. Collectively, the variations in soil respiration under warming, drought, and their interactions were further regulated by different biotic and abiotic factors. Considering future warming, when coupled with increased drought, our findings indicate the importance of considering the interactive effects of climate change on soil respiration and its components in arid and semi-arid regions over the next decade. [ABSTRACT FROM AUTHOR]

This article explores the application of thermodynamic perturbations to a historical midlatitude, wintertime, rain-on-snow flood event to evaluate how similar events may evolve under different climate forcings. In particular, we generate a hindcast of the 1996 Mid-Atlantic flood using an ensemble of 14-km variable-resolution simulations completed with the U.S. Department of Energy's global Energy Exascale Earth System Model (E3SM). We show that the event is skillfully reproduced over the Susquehanna River Basin (SRB) by E3SM when benchmarked against in situ observational data and high-resolution reanalyses. In addition, we perform five counterfactual experiments to simulate the flood under preindustrial conditions and four different levels of warming as projected by the Community Earth System Model Large Ensemble. We find a nonlinear response in simulated surface runoff and streamflow as a function of atmospheric warming. This is attributed to changing contributions of liquid water input from a shallower initial snowpack (decreased snowmelt), increased surface temperatures and rainfall rates, and increased soil water storage. Flooding associated with this event peaks from around +1 to +2 K of global average surface warming and decreases with additional warming beyond this. There are noticeable timing shifts in peak runoff and streamflow associated with changes in the flashiness of the event. This work highlights the utility of using storyline approaches for communicating climate risk and demonstrates the potential nonlinearities associated with hydrologic extremes in areas that experience ephemeral snowpack, such as the SRB. [ABSTRACT FROM AUTHOR]

Simple Summary: In this paper, the differences in carbon sequestration microbial communities in different wetland types and their main influencing factors are investigated. It was found that Proteobacteria was the dominant group of carbon sequestration microorganisms in the marsh wetland and river source wetland, and Cyanobacteria was the dominant group of carbon sequestration microorganisms in the lakeside wetland. The α diversity, relative abundance of Proteobacteria and total carbon content of the marsh wetland were the highest, followed by the river source wetland and lakeside wetland. The soil temperature and moisture and the total carbon content were the most important factors affecting the structures of carbon-sequestering microbial communities. Compared with the riverhead and lakeside wetlands, the marsh wetland has the highest carbon storage. The soil carbon storage in the Qinghai–Tibet Plateau wetlands is affected by microbiota and wetland types, but the response mechanisms of carbon sequestration microorganisms on the Qinghai–Tibet Plateau to different wetland types are still poorly described. To explore the differences in carbon sequestration microbial communities in different wetlands and the main influencing factors, this study took a marsh wetland, river source wetland and lakeside wetland of Qinghai Lake as the research objects and used high-throughput sequencing to study the functional gene, cbbL, of carbon sequestration microorganisms. The results showed that the dominant bacterial group of carbon sequestration microorganisms in marsh and river source wetlands was Proteobacteria, and the dominant bacterial group in the lakeside wetland was Cyanobacteria. The alpha diversity, relative abundance of Proteobacteria and total carbon content were the highest in the marsh wetland, followed by the river source wetland, and they were the lowest in the lakeside wetland. In addition, the physical and chemical characteristics of the three wetland types were significantly different, and the soil temperature and moisture and total carbon content were the most important factors affecting the community structures of carbon-sequestering microorganisms. There was little difference in the total nitrogen contents between the marsh wetland and river source wetland. However, the total nitrogen content was also an important factor affecting the diversity of the carbon sequestration microbial community. In summary, the wetland type significantly affects the process of soil carbon sequestration. Compared with the riverhead and lakeside wetlands, the marsh wetland has the highest carbon storage. [ABSTRACT FROM AUTHOR]

Groundwater and climate interact in a two-way manner. Precipitation ultimately controls groundwater recharge and, conversely, groundwater may influence climate through evapotranspiration. Yet very few global climate models or Earth system models actually simulate groundwater flows. And while the expected impacts of climate change on groundwater resources are the subject of a growing concern, global-scale groundwater–climate feedbacks have received very little attention so far. Here we show that the integration of unconfined aquifers in a global climate model can regionally affect the climate change signal on temperatures and precipitation. We assess the impact of groundwater under preindustrial and 4xCO2 conditions (after climate stabilization). In both cases, we find that groundwater has a cooling and a wetting effect in certain regions of the world. In eastern Europe, both these impacts are stronger in the warmer climate (4xCO2 forcing) where the presence of groundwater reduces the frequency of summer heatwaves by 40%, compared to a 15% reduction in the preindustrial world. This work constitutes one of the very first global assessments of the potential feedbacks of groundwater on climate change. Our results support the idea that groundwater should be represented in global climate models and Earth system models, as it does indeed play an active role in the climate system. [ABSTRACT FROM AUTHOR]

Tundra soils are one of the world's largest organic carbon stores, yet this carbon is vulnerable to accelerated decomposition as climate warming progresses. The landscape‐scale controls of litter decomposition are poorly understood in tundra ecosystems, which hinders our understanding of the global carbon cycle. We examined the extent to which the thermal sum of surface air temperature, soil moisture and permafrost thaw depth influenced litter mass loss and decomposition rates (k), and at which spatial thresholds an environmental variable becomes a reliable predictor of decomposition, using the Tea Bag Index protocol across a heterogeneous tundra landscape on Qikiqtaruk–Herschel Island, Yukon, Canada. We found greater green tea litter mass loss and faster decomposition rates (k) in wetter areas within the landscape, and to a lesser extent in areas with deeper permafrost active layer thickness and higher surface thermal sums. We also found higher decomposition rates (k) on north‐facing relative to south‐facing aspects at microsites that were wetter rather than warmer. Spatially heterogeneous belowground conditions (soil moisture and active layer depth) explained variation in decomposition metrics at local scales (< 50 m2) better than thermal sum. Surprisingly, there was no strong control of elevation or slope on litter decomposition. Our results reveal that there is considerable scale dependency in the environmental controls of tundra litter decomposition, with moisture playing a greater role than the thermal sum at < 50 m2 scales. Our findings highlight the importance and complexity of microenvironmental controls on litter decomposition in estimates of carbon cycling in a rapidly warming tundra biome. [ABSTRACT FROM AUTHOR]

Summary: Accounting for water limitation is key to determining vegetation sensitivity to drought. Quantifying water limitation effects on evapotranspiration (ET) is challenged by the heterogeneity of vegetation types, climate zones and vertically along the rooting zone.Here, we train deep neural networks using flux measurements to study ET responses to progressing drought conditions. We determine a water stress factor (fET) that isolates ET reductions from effects of atmospheric aridity and other covarying drivers. We regress fET against the cumulative water deficit, which reveals the control of whole‐column moisture availability.We find a variety of ET responses to water stress. Responses range from rapid declines of fET to 10% of its water‐unlimited rate at several savannah and grassland sites, to mild fET reductions in most forests, despite substantial water deficits. Most sensitive responses are found at the most arid and warm sites.A combination of regulation of stomatal and hydraulic conductance and access to belowground water reservoirs, whether in groundwater or deep soil moisture, could explain the different behaviors observed across sites. This variety of responses is not captured by a standard land surface model, likely reflecting simplifications in its representation of belowground water storage. [ABSTRACT FROM AUTHOR]

This study presents a long‐term assessment of the impact of projected climate change on selected agro‐climatic indicators in Poland. The analysis was based on an ensemble of six bias‐corrected EURO‐CORDEX projections covering the period from 2006 to 2100 under Representative Concentration Pathways: RCP4.5 and 8.5, and partly on simulations of an agro‐hydrological Soil and Water Assessment Tool model. The indicators included growing season (length, beginning, and ending date), growing degree days, frost days, accumulated frost, and planting and harvest timing. The study focused on four major crops cultivated in Poland, namely spring barley, rapeseed, maize silage, and potato. The analysis revealed a significant future increase in precipitation and mean temperature in Poland reaching +10.3% and 3.4°C by the end of century, respectively. Warmer conditions will significantly accelerate the beginning of the growing season (by up to 24 days) and delay its ending (by up to 18 days), consequently significantly extending its length throughout the country (by up to 42 days). A decrease is projected in potential soil moisture deficit by up to 26 mm by the end of century in the high‐end emission scenario. A significant advancement (by up to 30 days) in planting timing is projected for the future for all crops under consideration. A significant increase in growing degree days (by up to 760°C‐days) will also advance the harvest timing (by up to 54 days). The projected temperature increase over the winter season will result in a significant decrease in frost days (by 56 days) and accumulated frost (by 375°C‐days), which may lead to an increased presence of pests. This study can provide a scientific basis for assessing the future risks to the local agriculture from climate change and will be beneficial in planning adaption and mitigation actions for food security at the national and local scale. [ABSTRACT FROM AUTHOR]

Tunisia needs judicious water allocation to mitigate drought. Remote sensing tools, such as Sentinel-1 and Sentinel-2, can be used to estimate soil water status and monitor changes in soil moisture and vegetation cover. The study area covers the Kairouan governorate in the center of Tunisia, (35°40′33.29″ N, 10°5′30.26″ E), which is characterized by a flat relief (plain) covering an area of 6800 Km2 and belonging to the 'upper arid bioclimatic stage'. The study proposes a formula called "ER" to estimate soil water status from Sentinel-1 data, two color composition images to control changes in soil moisture and vegetation cover, and unsupervised ISODATA and k-means classifications to monitor the impact of climate change and land use. The data used are nine Sentinel-1 images and twelve Sentinel-2 images downloaded from the Copernicus platform at the dates given. The VV and VH Sentinel-1 GRD Level1 products were selected at different dates based on the daily precipitation amount (PA) of the studied region: PA > 55 mm,18.5 mm < PA < 33.5 mm, PA < 10 mm and PA = 0 mm for Sentinel-2, with results collected on 29/01, 23/2, 25/03, 24/04, 16/05, 11/05, 05/06, 13/06, 23/07, 24/08, 18/09 and 11/10 in 2019. For Sentinel-1, the dates of acquisition of images were 24/01, 23/02, 25/03, 12/04, 24/05, 12/06, 27/07, 15/09 and 09/10 in 2019. We chose cloudless images and we chose close dates for the two sentinels, which correspond to the dates of our field visit carried out in June and October 2019. Validation was carried out using two main criteria: (i) the measured mean precipitation deviation over successive months (EP) and (ii) the three reference land cover types (LC): cereals (LC1), fallow land (LC2) and bare soil (LC3). For this case study, three cases of EP were considered: (1) no precipitation (EP ≤ 0), (2) low precipitation (0 < EP ≤ 20 mm), and (3) high precipitation (EP > 20 mm). The results showed that, considering the VH polarization, we obtain ER < 0 for LC3 and ER ≈ 0 for the LC1 and LC2 terrestrial cultures when EP ≤ 0; ER > 0 for LC3 and ER ≈ 0 for the LC1 and LC2 terrestrial cultures when (0 < EP ≤ 20 mm); and ER > 0 for all LCs and the value increases with high rainfall. We validated these ER results using image composition and classified images. [ABSTRACT FROM AUTHOR]

Latent heat released during orographic precipitation over the Western Ghat (WG) Mountain drives the Indian Summer Monsoon. Instrumental data record a considerable spatiotemporal variation of rainfall amount along the mountain. Although Indian teak (Tectona grandis LF) samples from WG have been used earlier for reconstructing past monsoon rainfall, the effect of rainfall variation on the annual ring growth pattern along the mountain has not been extensively studied yet. To address this issue, tree-ring width data series from three locations—Dahanu (1763 -1985), Nagerhole (1703–2016), and Tekkedy (1785–2003) are presented in this study. The locations are situated along WG from north to south. Monthly mean rainfall data obtained from the nearest observatories show a decreasing (increasing) rainfall amount from north to south during summer monsoon (pre and post-monsoon). We obtain a significant positive correlation between ring width indices and monsoon rainfall and a negative correlation with summer (especially May) temperature suggesting a contrasting response of summer temperature and monsoon rain on teak growth. The correlation between rainfall and ring width varies from southern to northern WG (both in significance level and the number of months with significant correlation). While the southernmost location exhibits positive (significant) correlations for both pre and summer monsoon months, the correlations are found for only two summer monsoonal months in the northernmost location. This spatial correlation trend reflects the variation of the pre-monsoon to monsoon rainfall ratio observed in our study locations. This observation is further substantiated by soil moisture-ring width relationship. Furthermore, our study shows that ring width indices respond to a variation of western equatorial Pacific sea surface temperature and vapor pressure deficit. Our study, therefore, suggests that the Indian teak samples can be used for understanding regional and seasonal scale rainfall/soil moisture variation along the WG and teleconnection studies. [ABSTRACT FROM AUTHOR]

Relative humidity (RH) is projected to increase over ocean but decrease over land under anthropogenic warming. The land RH decrease was previously attributed to ocean influences on land changes. Here, we show that interactive soil moisture (SM) is necessary and may be sufficient for anthropogenic warming to reduce the land RH. The land RH decrease is absent in simulations with realistic land‐ocean geometry but fixed SM, and present in simulations with interactive SM but no oceans or changes in precipitation minus evaporation. The land RH decrease is coupled to the SM decline and the latter could be understood as a natural response of interactive SM to anthropogenic warming. Specifically, prior to adjustments in SM and RH, evaporation would increase by ∼6% K−1 following the Clausius–Clapeyron relation, outpacing the radiatively constrained ∼2% K−1 precipitation increase. This prior imbalance depletes SM and consequently reduces RH through the coupling between SM and RH. Plain Language Summary: As a measure of air wetness, relative humidity (RH) is projected to decrease over land under anthropogenic warming, contributing to increasing evaporative demand and intensifying droughts, heatwaves and wildfires. The land RH decrease was previously attributed to influences from ocean, but here we propose an alternative explanation. We first show that the land RH decrease is coupled with the soil moisture (SM) decline. Then, by excluding interactive SM and ocean influences respectively in warming simulations, we illustrate that interactive soil moisture (i.e., soil moisture is fed by precipitation minus evaporation and can in turn affect evaporation through moisture availability) is necessary and may be sufficient to produce a drier land under anthropogenic warming. A conceptual understanding of this declined SM and RH is provided based on theoretical evaporation equations. Key Points: We propose a new explanation for the projected decrease in land relative humidity under anthropogenic warmingComplex and idealized simulations show that interactive soil moisture (SM) is necessary and sufficient for anthropogenic warming to dry the landInteractive SM allows prior imbalance in evaporation and precipitation increases to dry the land independent of ocean influence [ABSTRACT FROM AUTHOR]