Reduced Soil Moisture Research Articles

Stochastic processes drive the dynamic assembly of bacterial communities in Salix matsudana afforested soils.

This study investigates the dynamic shifts in soil bacterial communities within a Salix matsudana afforested ecosystem transitioning from agricultural land. Understanding the temporal variability in bacterial diversity and community structures is crucial for informing forest management and conservation strategies, particularly in regions undergoing afforestation. We employed high-throughput sequencing across three distinct months (August, September, and October) to analyze the temporal variability in bacterial community composition and diversity. Network analysis was utilized to identify keystone species and assess community stability under varying environmental conditions, including fluctuations in temperature and precipitation. We uncover significant temporal variability in bacterial diversity and community structures, which are closely tied to fluctuations in temperature and precipitation. Our findings reveal the abundance of the dominant bacterial phyla, such as Actinobacteria and Proteobacteria, which did not change overall, highlighting the stability and resilience of the microbial community across seasonal transitions. Notably, the increasing similarity in community composition from August to October indicates a reduction in species turnover, likely driven by more homogeneous environmental conditions. Through comprehensive network analysis, we identify the pivotal role of keystone species, particularly the human pathogen Nocardia, in maintaining community stability under reduced soil moisture. The observed variations in community connectivity underscore the microbial community's resilience and adaptability to seasonal shifts, with higher stability in August and October contrasting with the instability observed in September. These results underscore the complex interplay between stochastic and deterministic processes in bacterial community assembly, significantly shaped by prevailing environmental conditions. The insights gained from this research have far-reaching implications for forestry management and conservation strategies, particularly in regions undergoing similar afforestation efforts.

Enhancement of soybean tolerance to water stress through regulation of nitrogen and antioxidant defence mechanisms mediated by the synergistic role of salicylic acid and thiourea

Water stress (WS) poses a significant threat to global food and energy security by adversely affecting soybean growth and nitrogen metabolism. This study explores the synergistic effects of exogenous salicylic acid (SA, 0.5 mM) and thiourea (TU, 400 mg L−1), potent plant growth regulators, on soybean responses under WS conditions. The treatments involved foliar spraying for 3 days before inducing WS by reducing soil moisture to 50% of field capacity, followed by 2 weeks of cultivation under normal or WS conditions. WS significantly reduced plant biomass, chlorophyll content, photosynthetic efficiency, water status, protein content, and total nitrogen content in roots and leaves. Concurrently, it elevated levels of leaf malondialdehyde, H2O2, proline, nitrate, and ammonium. WS also triggered an increase in antioxidant enzyme activity and osmolyte accumulation in soybean plants. Application of SA and TU enhanced the activities of key enzymes crucial for nitrogen assimilation and amino acid synthesis. Moreover, SA and TU improved plant growth, water status, chlorophyll content, photosynthetic efficiency, protein content, and total nitrogen content, while reducing oxidative stress and leaf proline levels. Indeed, the simultaneous application of SA and TU demonstrated a heightened impact compared to their separate use, suggesting a synergistic interaction. This study underscores the potential of SA and TU to enhance WS tolerance in soybean plants by modulating nitrogen metabolism and mitigating oxidative damage. These findings hold significant promise for improving crop productivity and quality in the face of escalating water limitations due to climate change.

Seasonal soil moisture thresholds inhibit bacterial activity and decomposition during drought in a tallgrass prairie

Soil moisture reductions during drought often inhibit soil microbial activity and inhibit decomposition rates by reducing microbial biomass or by altering microbial communities. Evidence suggests that soil water must drop below a critical threshold to inhibit microbial activity. Thus, it is likely that the seasonal timing of drought will determine the extent to which belowground processes are adversely impacted by drought. Specifically, the effects of drought might be minimal during cool, wet periods typical of late spring but dramatic during hot summer months with high evapotranspiration rates that lower soil moisture levels below the critical threshold. Here, we present results from a study designed to quantify the effect of drought on soil microbial abundance, community composition, and soil water diffusion across four months, and to then assess how drought impacts the microbial decomposition of leaf matter. We imposed a season‐long drought in a Wisconsin tallgrass prairie and measured soil moisture, bacterial composition and abundance, microbial respiration, and decomposition rates throughout the growing season. Bacterial communities varied considerably among dates, but drought did not affect either bacterial abundance or community composition. Microbial respiration declined significantly during periods of drought when soil pores likely became hydrologically isolated, ultimately reducing cumulative microbial respiration by 10%. The reduction in microbial activity in drought treatments caused a 50% decline in the decomposition of refractory material. Our study highlights that sublethal effects of drought on microbial communities, occurring only when soil moisture declined below a tolerance threshold, can have large impacts on microbial carbon release or decomposition, highlighting the need to incorporate such measures into future studies.

Moss crusts mitigate the negative impacts of shrub mortality on the nutrient multifunctionality of desert soils

AbstractThe distribution of biological soil crusts (BSCs) and shrubs in temperate deserts often forms a common landscape surface feature. As climate change continues, desert shrubs experience varying rates of mortality, which can have severe negative impacts on soil structure and function. However, it remains uncertain whether moss crusts, prevalent beneath shrub canopies, can mitigate the effects of shrub mortality on soil nutrient environments. Therefore, this study focuses on the Gurbantunggut Desert, a typical temperate desert in northern China, with a primary focus on the dominant shrubs, Ephedra przewalskii, and the advanced stage of moss crust development within BSCs. We collected soil samples from bare sand and moss crusts under living shrubs and dead shrubs and analyzed them for their carbon, nitrogen, phosphorus, and potassium contents. Additionally, we calculated soil nutrient multifunctionality, which measures a soil's ability to sustain multiple ecosystem services simultaneously, to provide a comprehensive assessment of the effects of shrub mortality on soil nutrient function. Our results indicate that shrub mortality led to reductions in soil moisture, pH, electrical conductivity, and levels of carbon, nitrogen, phosphorus, and potassium in exposed sand compared to the sand under living shrubs. However, the presence of moss crusts significantly alleviated the adverse effects of shrub mortality on soil carbon, nitrogen, phosphorus, and potassium levels. The nutrient multifunctionality index of the moss crust only decreased by 4%, while bare sand experienced a 67% reduction following shrub mortality. Standard error of the mean analysis results revealed that when shrubs and crusts coexisted, the impact of shrubs on soil nutrient multifunctionality was much stronger than that of the moss crust. Specifically, total nutrient content was the most influential factor driving changes in soil nutrient multifunctionality. In conclusion, in desert ecosystems with declining shrubs, moss crusts can mitigate the reduction in soil nutrient contents caused by shrub degradation, thereby maintaining soil stability and nutrient multifunctionality as a viable substitute.

Cascading effects of earthworm invasion increase graminoid density and rodent grazing intensities.

Human-mediated dispersal of non-native earthworms can cause substantial changes to the functioning and composition of ecosystems previously earthworm-free. Some of these earthworm species have the potential to "geoengineer" soils and increase plant nitrogen (N) uptake. Yet the possible consequences of increased plant N concentrations on rodent grazing remains poorly understood. In this study, we present findings from a common garden experiment with two tundra communities, meadow (forb dominated) and heath (shrub dominated), half of them subjected to 4 years of earthworm presence (Lumbricus spp. and Aporrectodea spp.). Within four summers, our earthworm treatment changed plant community composition by increasing graminoid density by, on average, 94% in the heath vegetation and by 49% in the meadow. Rodent winter grazing was more intense on plants growing in soils with earthworms, an effect that coincided with higher N concentrations in plants, indicating a higher palatability. Even though earthworms reduced soil moisture, plant community productivity, as indicated by vegetation greenness (normalized difference vegetation index), was not negatively impacted. We conclude that earthworm-induced changes in plant composition and trophic interactions may fundamentally alter the functioning of tundra ecosystems.

Disturbance reduces the moss‐dominated biocrust inhibition on infiltration and improves soil moisture storage within the Loess Plateau, China

Various factors influence biocrust effects on infiltration and soil moisture. On China's Loess Plateau, well‐developed moss‐dominated biocrusts reduce infiltration and suppress shrub growth, however, the interrelationships between rainfall conditions and disturbance management to alleviate these impacts are unknown. In a semiarid watershed on the Loess Plateau, we applied two forms of disturbance, scarification (controlled harrowing) and compaction (simulated grazing), at four intensity levels (control‐intact, light, moderate, and heavy) to well‐developed moss‐dominated biocrusts and a bare soil (BS) for comparisons to form eight treatments with three replications. Rainfall intensity and depth, soil moisture, run‐off, and sediment yield were measured during the rainy season (July–October). In total, well‐developed biocrusts did not significantly affect infiltration but reduced soil moisture at depths of 120–180 cm (p < 0.05), and disturbance increased infiltration and deep soil moisture beneath biocrusts (p < 0.05). Rainfall conditions changed the effects of biocrusts and disturbance. Under long, low‐intensity rainfall, moss‐dominated biocrust infiltration was slightly greater than BS, but scarification increased infiltration and compaction reduced it (p < 0.001). Under short, high‐intensity rainfall, biocrusts reduced infiltration, and disturbance intensity increased infiltration and sediment yields (p < 0.001). Light grazing or using light or moderate scarification improves well‐developed moss‐dominated biocrust infiltration in the pastures during May–June before the rainy season during July–October on the Loess Plateau, while avoiding increased soil erosion.

Cultivar-specific dynamics: unravelling rhizosphere microbiome responses to water deficit stress in potato cultivars

BackgroundGrowing evidence suggests that soil microbes can improve plant fitness under drought. However, in potato, the world’s most important non-cereal crop, the role of the rhizosphere microbiome under drought has been poorly studied. Using a cultivation independent metabarcoding approach, we examined the rhizosphere microbiome of two potato cultivars with different drought tolerance as a function of water regime (continuous versus reduced watering) and manipulation of soil microbial diversity (i.e., natural (NSM), vs. disturbed (DSM) soil microbiome).ResultsWater regime and soil pre-treatment showed a significant interaction with bacterial community composition of the sensitive (HERBST) but not the resistant cultivar (MONI). Overall, MONI had a moderate response to the treatments and its rhizosphere selected Rhizobiales under reduced watering in NSM soil, whereas Bradyrhizobium, Ammoniphilus, Symbiobacterium and unclassified Hydrogenedensaceae in DSM soil. In contrast, HERBST response to the treatments was more pronounced. Notably, in NSM soil treated with reduced watering, the root endophytic fungus Falciphora and many Actinobacteriota members (Streptomyces, Glycomyces, Marmoricola, Aeromicrobium, Mycobacterium and others) were largely represented. However, DSM soil treatment resulted in no fungal taxa and fewer enrichment of these Actinobacteriota under reduced watering. Moreover, the number of bacterial core amplicon sequence variants (core ASVs) was more consistent in MONI regardless of soil pre-treatment and water regimes as opposed to HERBST, in which a marked reduction of core ASVs was observed in DSM soil.ConclusionsBesides the influence of soil conditions, our results indicate a strong cultivar-dependent relationship between the rhizosphere microbiome of potato cultivars and their capacity to respond to perturbations such as reduced soil moisture. Our study highlights the importance of integrating soil conditions and plant genetic variability as key factors in future breeding programs aiming to develop drought resistance in a major food crop like potato. Elucidating the molecular mechanisms how plants recruit microbes from soil which help to mitigate plant stress and to identify key microbial taxa, which harbour the respective traits might therefore be an important topic for future research.

Variations in Summer Surface Air Temperature Over the Eastern Tibetan Plateau: Connection With Barents‐Kara Spring Sea Ice and Summer Arctic Oscillation

AbstractVariations in surface air temperature on the eastern Tibetan Plateau (TP‐SAT) during boreal summer, related to Barents‐Kara spring sea ice and summer Arctic Oscillation (AO), are investigated using observations and ERA‐5 reanalysis data during 1979–2018. Results show that the primary mode of summer eastern TP‐SAT (SAT_EOF1) is characterized by the consistent warming pattern with larger values over the northeastern TP, which is linked with the anticyclonic circulation located in the northeastern flank of the TP. This anticyclone enhances westward water vapor transport, warm temperature advection, and causes descending over the eastern TP, Descending further results in deceased middle level cloud cover and increased solar radiation, accordingly, favoring the eastern TP warming. Further statistical analysis reveals a robust connection between Barents‐Kara spring sea ice, summer AO and SAT_EOF1. Moreover, anticyclonic anomaly located in the northeastern region of the TP acts as an important driver of this consistent warming pattern over the eastern TP, which is modulated by two individual Rossby wave trains from the northwestern Russia and northwestern Atlantic. The spring sea ice in Barents‐Kara could cause decreased precipitation and reduced soil moisture in northwestern Russia during following summer, which further induces the Eurasian‐like teleconnection and affects the anticyclonic anomaly situated in the northeastern flank of the TP, thereby favoring eastern TP warming. In addition, from northwestern Atlantic to northeastern region of the TP, the Rossby wave train is mainly affected by summer AO, with positive AO causing anticyclonic anomaly over northeast of the TP, thus contributing to the TP warming.

Plant litter loss exacerbates drought influences on grasslands.

Plant litter is known to affect soil, community, and ecosystem properties. However, we know little about the capacity of litter to modulate grassland responses to climate change. Using a 7-yr litter removal experiment in a semiarid grassland, here we examined how litter removal interacts with a 2-yr drought to affect soil environments, plant community composition, and ecosystem function. Litter loss exacerbates the negative impacts of drought on grasslands. Litter removal increased soil temperature but reduced soil moisture and nitrogen mineralization, which substantially increased the negative impacts of drought on primary productivity and the abundance of perennial rhizomatous graminoids. Moreover, complete litter removal shifted plant community composition from grass-dominated to forb-dominated and reduced species and functional group asynchrony, resulting in lower ecosystem temporal stability. Our results suggest that ecological processes that lead to reduction in litter, such as burning, grazing, and haying, may render ecosystems more vulnerable and impair the capacity of grasslands to withstand drought events.

Impacts of aboveground litter and belowground roots on soil greenhouse gas emissions: Evidence from a DIRT experiment in a pine plantation

Plant detritus alteration may influence soil greenhouse gas emissions, but the direction, extent and mechanisms remain uncertain. Here we conducted a DIRT (Detritus Input and Removal Treatment) experiment in a Pinus sylvestris var. mongolica plantation in Saihanba (Hebei Province, China), manipulating aboveground litter (L-: litter removal, L: normal litter, L+: litter doubling) and belowground roots (R-: root removal, R: with root) resulting in six treatments. We measured CO2, N2O, and CH4 fluxes during 2019 and 2020 growing seasons, along with soil physicochemical, enzymatic and microbial variables. Our findings revealed that soil CO2 and N2O emissions increased with litter input, while CH4 uptake decreased. The absence of roots decreased soil CO2 emission and CH4 uptake but increased N2O emission. Aboveground litter enhanced the carbon cycling variables, such as extractable organic carbon (EOC), the ratio of soil extractable organic carbon to extractable total nitrogen (EOC:ETN), soil carbon mineralization rate (Cmin), and peroxidase activity (PER), resulting in increased CO2 emission. In contrast, the absence of roots increased the nitrogen cycling variables, such as soil extractable total nitrogen (ETN), nitrate nitrogen content (NO3−-N), the ratio of soil extractable organic carbon to extractable total nitrogen (EOC:ETN), soil net nitrogen mineralization rate (Nmin), and the abundance of ammonia-oxidizing bacteria (AOB), leading to increased N2O emission. Moreover, soil CH4 uptake was mainly influenced by soil microclimate: aboveground litter input reduced CH4 uptake by lowering soil temperature, while belowground roots benefited CH4 uptake via reducing soil moisture by water uptake. Taken together, our study suggests that soil CO2, N2O, and CH4 emissions (or uptake) are influenced by both aboveground and belowground plant inputs through various pathways. While aboveground litter input promotes the emissions of greenhouse gasses, the mitigating effect of belowground roots on N2O and CH4 partially offsets the increment of CO2 emission in this plantation.

Intensification of heatwaves in Central Asia from 1981 to 2020 – Role of soil moisture reduction

Heatwaves pose increasing threats on water resources for ecosystems and human consumption especially in arid region, such as Central Asia (CA). As the hinterland of Eurasia, water scarcity and land degradation in CA have increased its vulnerability to heatwaves. While the frequency of heatwaves has been examined, more heatwave metrics such as timing are less known, possible influences of soil moisture on heatwave changes in this region are not fully understood. Using reanalysis and observational datasets, here we examine the spatial–temporal changes of heatwaves in CA during 1981–2020 and the role of various associated factors including soil moisture. The results show that the extreme heatwaves occurred more frequently in northwestern Kazakhstan. Temporally, heatwaves have been intensifying with significant increases in frequency (0.10 events/year), intensity (0.81 °C/year), and duration (0.08 days/year) since the 1980 s, and these trends have accelerated since 1997. The first yearly heatwave event tended to occur earlier in more recent decades, indicating an advanced heatwave season. We also found that the heatwave occurrences were significantly correlated with hydro-meteorological factors. In northwestern of CA, extreme heatwaves are exacerbated by a rapid decrease in soil moisture resulting from reduced precipitation and increased solar net radiation in this area. Our findings provide a scientific basis for understanding the mechanisms and predictions of heatwave in arid regions from the climate change perspective.

Microhabitat requirements of the uncompahgre fritillary butterfly (Boloria improba acrocnema) and climate change implications

The Uncompahgre fritillary butterfly (Boloria improba acrocnema Gall LF, Sperling FAH (1980) A new high altitude species of Boloria from southwestern Colorado (Nyphalidae), with a discussion of phenetics and hierarchical decisions. J Lepidopterists’ Soc 34:230–252 1980) was listed as federally endangered in 1991 and is considered a habitat indicator for alpine ecosystem health. They are found on patches of Salix nivalis in isolated habitats of the San Juan Mountains, Colorado, USA. Here, we estimated historical B. i. acrocnema abundance from annual distance sampling (2003–2020) at seven sub-colonies and sampled current (July 2021) measurements of herbaceous coverage, soil moisture content, and slope, aspect, and elevation at 700 sample sites. We used regression models to test the effects of these microhabitat characteristics on historical abundance. Our results show that increases in slope from 11° to 31°, individual coverage of five alpine plant species (S. nivalis, Geum rossii, Phacelia sericea, Noccaea fendleri, and Lewisia pygmaea), and soil moisture content between 0.09 m3/m3 and 0.38 m3/m3 positively influence butterfly abundance. However, increases in elevation, bare ground coverage, and presence of Salix planifolia, Aster alpinus, Antennaria media, and Androsace chamaejasme were correlated with lower abundance estimates.Implications for insect conservation Effects of climate change which decrease coverage of these alpine plant species, allow encroachment of lower elevation species, or reduce soil moisture will decrease B. i. acrocnema abundance. These results emphasize the extinction risk of B. i. acrocnema due to range limitations and prolonged drought conditions in the Western U.S. By defining additional resource requirements of B. i. acrocnema, we can model climate effects on survivorship and consider nearby microhabitats that may be habitable by this endangered species.

Soil microbial diversity and network complexity drive the ecosystem multifunctionality of temperate grasslands under changing precipitation

Soil microbiomes play a critical role in regulating ecosystem multifunctionality. However, whether and how soil protists and microbiome interactions affect ecosystem multifunctionality under climate change is unclear. Here, we transplanted 54 soil monoliths from three typical temperate grasslands (i.e., desert, typical, and meadow steppes) along a precipitation gradient in the Mongolian Plateau and examined their response to nighttime warming, decreased, and increased precipitation. Across the three steppes, nighttime warming only stimulated protistan diversity by 15.61 (absolute change, phylogenetic diversity) but had no effect on ecosystem multifunctionality. Decreased precipitation reduced bacterial (8.78) and fungal (22.28) diversity, but significantly enhanced soil microbiome network complexity by 1.40. Ecosystem multifunctionality was reduced by 0.23 under decreased precipitation, which could be largely attributed to the reduced soil moisture that negatively impacted bacterial and fungal communities. In contrast, increased precipitation had little impact on soil microbial communities. Overall, both bacterial and fungal diversity and network complexity play a fundamental role in maintaining ecosystem multifunctionality in response to drought stress. Protists alter ecosystem multifunctionality by indirectly affecting microbial network complexity. Therefore, not only microbial diversity but also their interactions (regulated by soil protists) should be considered in evaluating the responses of ecosystem multifunctionality, which has important implications for predicting changes in ecosystem functioning under future climate change scenarios.

Safflower (Carthamus tinctorius L.) crop adaptation to residual moisture stress: conserved water use and canopy temperature modulation are better adaptive mechanisms.

Oilseeds with high productivity and tolerance to various environmental stresses are in high demand in the food and industrial sectors. Safflower, grown under residual moisture in the semi-arid tropics, is adapted to moisture stress at certain levels. However, a substantial reduction in soil moisture has a significant impact on its productivity. Therefore, assessing genetic variation for water use efficiency traits like transpiration efficiency (TE), water uptake, and canopy temperature depression (CTD) is essential for enhancing crop adaptation to drought. The response of safflower genotypes (n = 12) to progressive soil moisture depletion was studied in terms of water uptake, TE, and CTD under a series of pot and field experiments. The normalised transpiration rate (NTR) in relation to the fraction of transpirable soil water (FTSW) varied significantly among genotypes. The genotypes A-1, Bhima, GMU-2347, and CO-1 had higher NTR-FTSW threshold values of 0.79 (R2 = 0.92), 0.74 (R2 = 0.96), 0.71 (R2 = 0.96), and 0.71 (R2 = 0.91), respectively, whereas GMU-2644 had the lowest 0.38 (R2 = 0.93). TE was high in genotype GMU-2347, indicating that it could produce maximum biomass per unit of water transpired. At both the vegetative and reproductive stages, significant positive relationships between TE, SPAD chlorophyll metre reading (SCMR) (p < 0.01) and CTD (p < 0.01) were observed under field conditions by linear regression. The genotypes with high FTSW-NTR thresholds, high SCMR, and low CTD may be useful clues in identifying a genotype's ability to adapt to moisture stress. The findings showed that the safflower genotypes A-1, Bhima, GMU-2347, and CO-1 exhibited an early decline and regulated water uptake by conserving it for later growth stages under progressive soil water depletion.

PENGARUH DURASI IRIGASI TETES TERHADAP REDUKSI LENGAS TANAH PADA LAHAN POLYBAG

Soil moisture is an important factor needed by plants for growth, and therefore the amount of soil moisture that can be stored depends on the type of soil or the composition of the soil-forming materials. Compost is one of the nutrients that is often used in the manufacture of planting media on land in the form of polybags, and the amount of compost composition on the soil is thought to greatly affect the ability to store water in the media, both the size and duration of storage. This study aims to examine the effect of using compost on storage of irrigation water in the form of soil moisture and how long it can be stored. in three-storey drip irrigation. The main data analyzed is soil moisture data (w) and the results of the analysis and discussion and conclusions are drawn descriptively. The results of the analysis show that the initial soil moisture content in the range of 19% -25%, can be given additional soil moisture by irrigation of about 12%. The average daily decrease in soil moisture that occurs in soil variation 1 (70%: 30% ) is 3% -4.4% and in soil variation 2 (50%: 50%), the average moisture reduction is around 3% -6%, soil moisture reduction in variation 2 is greater than soil variation 1 for all floors.

Hydrological effects of vegetation restoration in karst areas research: Progress and challenges

Vegetation restoration is an important way to improve karst ecosystems. Currently, research on the hydrological effects of vegetation restoration in karst areas has made great progress. However, the results obtained from the relevant studies have some limitations and uncertainties. Thus, this paper summarizes the research progress on the effects of karst vegetation restoration on five aspects: soil moisture, evapotranspiration, surface and subsurface runoff, water use efficiency and utilization strategies, and runoff generation and sink processes. The research showed that the existing studies’ evidence of the influence of vegetation restoration on runoff is still contradictory, with some suggesting that vegetation restoration can reduce soil moisture and runoff value, and others saying it can increase it. Furthermore, the ability of different types of vegetation to recover from water deficits varies across time scales, so focusing on spatial and temporal variations in evapotranspiration in karst regions is important. This article investigates water use efficiency in karst areas, as it is mainly controlled by vegetation types, climatic conditions, human activities and geological conditions, meaning the hydrogeological structure of karst has a very fundamental influence on water use efficiency in that region, we also investigate the effects of subsurface conditions in karst areas on the runoff generation and sink process as well as the type and stage of vegetation restoration, and geological factors affect vegetation restoration. Studies on the hydrological effects of vegetation restoration, however, are based on the relationship with a single element, describing its spatial and temporal variability, and they do not sufficiently quantify the reaction principles. This article also analyzes the problems and challenges in current studies, and proposes a combination of geophysical detection, establishing a dynamic model of the co-evolution of karst ecohydrology and surface karst zone mean with fieldwork to further verify the scientific validity of the results.

Effects of simulated precipitation gradients on nutrient resorption in the desert steppe of northern China.

Changes in rainfall induced by climate change will likely influence the utilization of water resources and affect the nutrient cycle in plants in the water-limited desert steppe. In order to understand the response of nitrogen and phosphorus resorption characteristics of plant leaves to precipitation changes, this study compared the nitrogen (N) resorption efficiency, phosphorus (P) resorption efficiency and influencing factors of plants in a desert steppe through water treatment experiments. A 4-year field experiment was performed to examine the response and influencing factors of nitrogen (N) and phosphorus resorption efficiency of five dominant plants in Stipa breviflora desert steppe to simulated precipitation change in Inner Mongolia, with four simulated precipitation gradients including reducing water by 50%, natural precipitation, increasing water by 50%, increasing water by 100%. Compared with natural precipitation, increasing water by 100% significantly increased soil moisture, and significantly increased the aboveground biomass of S. breviflora, C. songorica, A. frigida, decreased the N concentrations in green leaves of S. breviflora, Cleistogenes songorica, Artemisia frigida, Kochia prostrata, decreased the N concentrations in senesced leaves of C. songorica, decreased the P concentrations in green leaves of K. prostrata and Convolvulus ammannii, decreased the NRE of S. breviflora. NRE was significantly negatively correlated with N concentration in senesced leaves, and PRE was significantly negatively correlated with P concentration in senesced leaves. Increasing water indirectly reduces NRE by reducing plant leaf green leaves nitrogen concentration, and decreasing water indirectly reduces PRE by reducing soil moisture.

A comparative analysis of agronomic water-use efficiency and its proxy measures as derived from key morpho-physiological and supportive quantitative genetics attributes of perennial ryegrass under imposed drought.

Water-use efficiency (WUE) is an under-researched but very important drought tolerance trait in forage breeding. This research estimated quantitative genetic parameters of morpho-physiological traits linked to agronomic water-use efficiency (WUEA) and its proxy measures based on δ13C (WUEi) or gas exchange (evapotranspiration, WUEAET, or stomatal conductance WUEASC) of genotypes from half-sib families of Lolium perenne L. (PRG) in a simulated summer drought cycle. Principal component analysis (PCA) of trait data distinguished a group of PRG genotypes where high WUEA and dry matter yield was associated with deep rooting, leaf hydration at more negative leaf osmotic and water potential, and reduced soil moisture depletion. Plants with this trait association sustained net assimilation and postdefoliation regrowth in drought. However, WUEi, WUEASC, and WUEAET were poorly correlated with most traits of interest at p < .05. Another PCA revealed a weak association between WUEA and its proxy measures under conditions tested. Quantitative genetic parameters including high estimates of narrow-sense heritability () of WUEA and related traits emphasized the genetic potential of the key trait combination for selecting PRG for improved drought tolerance. Research findings highlight the relative importance of WUEA and its proxy measures in the broad definition of PRG drought tolerance for breeding purposes.

How Unusual Is the 2022 European Compound Drought and Heatwave Event?

AbstractThe 2022 Compound Drought and Heatwave (CDHW) caused widespread crop damage, water shortages, and wildfires across Europe. Our study analyzed this event’s severity and return period (RP) and compared it with past mega CDHWs in Europe. The hardest‐hit areas were Iberian Peninsula, France, and Italy, where temperatures exceeded 2.5°C above normal, and severe droughts persisted from May to August. Using a Bayesian approach, we estimated the RP for the 2022 CDHW event, which was unprecedented in Northern Italy, Iberian Peninsula, and western parts of France, with RPs of 354, 420, and 280 years, respectively. The reduced soil moisture due to precipitation deficits and high temperatures contributed to the persistence and severity of drought, creating a positive feedback loop where dry soils led to even drier conditions. In light of our findings, it is evident that global warming poses increased risks of severe CDHW events, which are likely to increase.

Dynamics of physical properties of soils and humus reserves in salted soils under desertification

The dynamics of the physical properties and reserves of humus in saline soils of an arid semi-desert zone is presented. The basis for the research was observational data for 2010-2022. in a typical hilly landscape of the Astrakhan region. A grid of 100 × 100 m was laid. Soil studies were carried out at the grid nodes along the sampling layers. We studied the change in physical properties (soil moisture; salt content according to the amount of dense residue; soil density; filtration coefficient; soil porosity; moisture reserve), humus reserves and salt state of saline soils under desertification. Comparative analysis showed that negative changes have taken place in the study area and it can be stated that the processes of soil degradation and desertification are intensively developing. It has been established that in the soil layer of 0–40 cm there was a significant reduction in soil moisture reserves against the background of an increase in maximum air and soil surface temperatures, as well as changes in the hydrological regime because of the embankment of the territory. Dehumification processes are observed. The most clearly negative trend was revealed for meadow solonchaks. The change in the hydrological regime of the territory because of embankment contributes to an increase in the areas of automorphic soils in the landscape and a reduction in the areas of meadow soils. An increase in the degree of salinity and compaction was recorded for automorphic zonal soils. The physical destruction of the Baer's hills exacerbates the processes of degradation and the development of desertification in such conditions.