Changes In Precipitation Patterns Research Articles

Change in precipitation pattern over South Asia in response to the trends in regional warming and free-tropospheric aerosol loading

Spatial and temporal shifts in rainfall patterns over South Asia and the adjoining Seas during the pre-monsoon season have been observed over the past 2 decades from 2000 to 2019. Aerosol particles suspended above the boundary layer are a contributing factor to these changes. These particles not only alter cloud characteristics, but also diminish the lapse rate, thereby suppressing convective activity, leading to precipitation anomalies. Over the past 2 decades, high-rainfall regions have experienced declining rainfall, while low-rainfall regions have received increased rainfall. Coinciding with notable anomalies in precipitation, contrasting trends in aerosol optical depth, particularly due to absorbing aerosols in the elevated regions of the atmosphere, are seen. Apart from aerosols, several factors are considered that are critical in modifying precipitation patterns over the study region, such as water vapor content, convective processes, and lower-level relative humidity. We observed a potential transport of excess water vapor by ambient circulation from the oceanic regions having reduced rain, such as Bay of Bengal and the Arabian Sea, to higher latitudes enabling precipitation anomaly at distant locations.

Natural Aerosols, Gaseous Precursors and Their Impacts in Greece: A Review from the Remote Sensing Perspective

The Mediterranean, and particularly its Eastern basin, is a crossroad of air masses advected from Europe, Asia and Africa. Anthropogenic emissions from its megacities meet over the Eastern Mediterranean, with natural emissions from the Saharan and Middle East deserts, smoke from frequent forest fires, background marine and pollen particles emitted from ocean and vegetation, respectively. This mixture of natural aerosols and gaseous precursors (Short-Lived Climate Forcers—SLCFs in IPCC has short atmospheric residence times but strongly affects radiation and cloud formation, contributing the largest uncertainty to estimates and interpretations of the changing cloud and precipitation patterns across the basin. The SLCFs’ global forcing is comparable in magnitude to that of the long-lived greenhouse gases; however, the local forcing by SLCFs can far exceed those of the long-lived gases, according to the Intergovernmental Panel on Climate Change (IPCC). Monitoring the spatiotemporal distribution of SLCFs using remote sensing techniques is important for understanding their properties along with aging processes and impacts on radiation, clouds, weather and climate. This article reviews the current state of scientific know-how on the properties and trends of SLCFs in the Eastern Mediterranean along with their regional interactions and impacts, depicted by ground- and space-based remote sensing techniques.

Effects of changes in precipitation patterns and stream flow on stream DOC and [formula omitted] concentrations in a headwater catchment in a subtropical region of southern China

Study regionThe Guantian headwater watershed is located in the subtropical region of South China. Study focusThis study examined how changes in precipitation and consequent shifts in streamflow affect dissolved organic carbon (DOC) and nitrate (NO3−) concentrations in a headwater stream. New hydrological insights for the regionThe results indicate that stream DOC and NO3− concentrations decrease from spring to winter (0.16 mg/L/month for DOC and 0.18 mg/L/month for NO3−) and have a generally positive relationship with streamflow (p < 0.05). Changes in precipitation-concentration, precipitation-amount and consequent shifts in streamflow remarkably affect stream DOC and NO3− concentrations. When precipitation events are more heavily concentrated (when precipitation concentration index (PCI) changed from 12.81 to 18.33) from May to July, the stream DOC and NO3− concentrations tend to increase from May to July but decrease before and after this period. In addition, an increase in precipitation-amount tends to increase stream DOC and NO3− concentrations before the occurrence of peak flow and in the dry period from September to December, but decreases them in the wet period from June to September. When the precipitation-amount decreases, the trend of the change in concentration is exactly the opposite. These findings suggest that stream DOC and NO3− concentrations in the headwater stream are highly chemodynamic: they are transport-limited before the occurrence of high flow and in the dry period from September to December, while they are supply-limited in the June-September period.

Key drivers of vulnerability to rainfall flooding in New Orleans

IntroductionFuture urban stormwater flood risk is determined by the confluence of both climate-driven changes in precipitation patterns and the effectiveness of flood mitigation systems, such as urban drainage and pump systems. This is especially true in coastal cities protected by levee systems like New Orleans, where even present-day rainfall would be enough to cause serious flooding in the absence of extensive stormwater drainage and pumping. However, while the uncertainties associated with climate change have been well studied, uncertainties in infrastructure performance and operation have received less attention.MethodsWe investigated how these interrelated sets of uncertainties drive flood risk in New Orleans using a Robust Decision Making (RDM) approach. RDM is a framework for Decision Making Under Deep Uncertainty (DMDU) that leverages simulation models to facilitate exploration across many possible futures and the identification of decision-relevant scenarios. For our work, we leveraged a detailed Storm Water Management Model (SWMM) representation of the New Orleans urban stormwater management system to examine flood depths across the city when faced with different levels of future precipitation, sea-level rise, drainage pipe obstruction, and pumping system failure. We also estimated direct flood damage for each neighborhood in the city for this scenario ensemble. These damage estimates were then subjected to vulnerability analysis using scenario discovery—a technique designed to determine which combinations of uncertainties are most stressful to the system in terms of an outcome of interest (excess flood damage).ResultsOur results suggest that key drivers of vulnerability depend on geographic scale. Specifically, we find that possible climate-driven precipitation increases are the most important determinant of vulnerability at the citywide level. However, for some individual neighborhoods, infrastructure operation challenges under present day conditions are a more significant driver of vulnerability than possible climate-driven precipitation increases.

Tree species mixing effects on the radial growth of Pinus massoniana and Castanopsis hystrix: A comparison between even-aged and uneven-aged stands

The establishment of mixed-species forests with complex structures and high biodiversity has emerged as a key approach for enhancing productivity and maintaining the stability of plantation forests. However, how the mixing effect changes with stand development and climate variation is still unclear. Additionally, little is known about how the mixing effects vary between even- and uneven-aged mixed planting strategies based on the same species combinations and site conditions. In this study, we used dendrochronological methods to reconstruct 37 years of annual growth series for even-aged mixed plantations (EMs) and uneven-aged mixed plantations (UEMs) of Pinus massoniana and Castanopsis hystrix, as well as their respective monocultures at the individual tree (286 trees in total) level. We found that in EMs, the growth of P. massoniana and C. hystrix was 20.8 % lower and 26.2 % higher than those of their monocultures, respectively. However, the growth of P. massoniana remained unchanged during the first 17 years of mixing, after which it was significantly suppressed by C. hystrix. The growth of P. massoniana and C. hystrix in the UEMs was 20.8 % and 26.2 % lower than that in their monocultures, respectively. Remarkably, the mixing effect on the growth of P. massoniana shifted from suppression to promotion after 30 years of mixing. Furthermore, the relative growth of P. massoniana in the UEMs increased with dry season precipitation. These results indicate that transforming pure plantations into uneven-aged mixed plantations may be a crucial forest management strategy for enhancing tree growth and to improving adaptation to future precipitation pattern changes. However, in EMs, thinning should be conducted before fast-growing, shade-intolerant species experience intense light competition.

Evaluating the potential of recycled water use for irrigation in southern Maryland: impact on groundwater conservation and crop yield

ABSTRACT Climate change and rainfall variability are driving many farmers to adopt irrigation, who were historically within rain-dependent regions, to sustain crop productivity. In the Mid-Atlantic region, irrigation in agriculture has grown since the 1980s due to rising temperatures and changes in precipitation patterns. Dry summers and uneven seasonal rainfall have necessitated a shift toward irrigation, particularly in Maryland's Coastal Plain. However, high dependence on confined groundwater for irrigation around this area has strained aquifers. To mitigate this strain, exploring alternative water sources is now important. This study investigates the viability of utilizing treated wastewater from plants as an irrigation substitute in Maryland's Coastal Plain. Using the Soil and Water Assessment Tool, the research evaluates crop productivity and irrigation needs under various climate scenarios. Results indicate that recycled water from nearby treatment plants can meet crop water requirements during wet years and partially during moderate and dry years, reducing aquifer reliance by 56 and 30%, respectively. This framework aims to boost yields while conserving freshwater resources. By serving as a decision support tool, stakeholders can assess the feasibility of recycled water for irrigation, thereby potentially reducing strain on confined aquifers.

Long-term effects of early life rainfall shocks on foundational cognitive skills: Evidence from Peru

Global warming is changing precipitation patterns, particularly harming communities in low-and-middle income countries (LMICs). Whilst the long-term effects of being exposed to rainfall shocks early in life on school-achievement tests are well-established, there is little population-based evidence from LMICs on the mechanisms through which these shocks operate. Executive functions (EFs) are key for children’s learning abilities. This paper analyses the effects of early exposure to rainfall shocks on four foundational cognitive skills (FCSs), including EFs that have been found to be key predictors of educational success. These skills were measured via a series of tablet-based tasks administered in Peru as part of the Young Lives longitudinal study (YLS). We combine the YLS data with gridded data on monthly precipitation to generate monthly, community-level rainfall shock estimates. The key identification strategy relies on temporary climatic shocks being uncorrelated with other latent determinants of FCSs development. Our results show significant negative effects of early life exposure to rainfall shocks on EFs—especially, on working memory—measured in later childhood. We also find evidence of rainfall shocks decreasing households’ abilities to invest in human capital, which may affect both FCSs and domain-specific test scores. Finally, there is suggestive, but not conclusive, evidence that a conditional-cash-transfer program providing poor households with additional financial resources might partially offset the effects of the rainfall shocks.

Response of stomatal density and size in Betula ermanii to contrasting climate conditions: The contributions of genetic and environmental factors.

As plant distribution and performance are determined by both environmental and genetic factors, clarifying the contribution of these two factors is a key for understanding plant adaptation and predicting their distribution under ongoing global warming. Betula ermanii is an ideal species for such research because of its wide distribution across diverse environments. Stomatal density and size are crucial traits that plants undergo changes in to adapt to different environments as these traits directly influence plant photosynthesis and transpiration. In this study, we conducted a multi-location common garden experiment using B. ermanii to (1) clarify the contribution of both environmental and genetic factors to the variation in stomatal density and size of B. ermanii, (2) demonstrate the differences in the plasticity of stomatal density and size among B. ermanii populations, and (3) understand how stomatal density and size of B. ermanii would respond to increased temperature and changing precipitation patterns. Genetic factors played a more significant role in stomatal size than environmental factors, suggesting that B. ermanii struggles to adjust its stomatal size in response to a changing environment. Our results also revealed a positive correlation between stomatal size plasticity and original habitat suitability, indicating that in B. ermanii populations in harsh environments exhibit lower adaptability to environmental shifts. Although stomatal density and size of B. ermanii showed the significant responses to increased temperature and shifting precipitation patterns, the response ranges of stomatal density and size to the environmental factors varied among populations. Our findings highlighted the interplay between genetic and environmental factors in determining the intraspecific variation in stomatal density and size in B. ermanii. This indicated that certain populations of B. ermanii exhibit limited stomatal plasticity and adaptability, which could directly affect photosynthesis and transpiration, suggesting potential population-specific fitness implications for B. ermanii under future climate change.

The Responses of Soil Nitrogen Transformations to Rainfall Reduction Mainly Occurred in the Early Growing‐Season in a Temperate Meadow

AbstractDrought is expected to increase in temperate regions in the coming decades due to global climate change and will strongly affect nitrogen (N) transformation and balance. However, the underlying mechanisms (soil microenvironment vs. biotic community) of rainfall reduction induced changes in soil N transformation rates, and whether the responses of soil N transformation rates to rainfall reduction vary over time remains poorly understood. In this study, we experimentally examined rainfall reduction effects on soil N transformation rates over two (the second and third experimental years) growing‐seasons in a temperate meadow. We applied four treatments: ambient rainfall, 30%, 50%, and 70% reduction in rainfall. Our findings demonstrated that, 70% rainfall reduction significantly decreased the average net N mineralization and nitrification rates by 68.4% and 72.0%, respectively. Soil nitrous oxide emission was profoundly varied between the experimental years, with it was sensitive no only to changes in annual precipitation amount, but also to seasonal distribution, the highest emissions appeared at the early growing‐season. Moreover, plant diversity, microbial biomass, and soil NO3−‐N content mainly regulated soil N transformation rates in response to rainfall reduction in the greater annual precipitation year; but soil N transformation rates were mainly controlled by soil water content in the less annual precipitation year. We suggest that to accurately project future ecosystem functions and improving the prediction of N cycling responses to changing precipitation patterns, stronger focus should be allocated not only to changes in precipitation amounts, but also to inter‐ and intra‐annual differences in precipitation distribution.

Abrupt reduction in shipping emission as an inadvertent geoengineering termination shock produces substantial radiative warming

Human activities affect the Earth’s climate through modifying the composition of the atmosphere, which then creates radiative forcing that drives climate change. The warming effect of anthropogenic greenhouse gases has been partially balanced by the cooling effect of anthropogenic aerosols. In 2020, fuel regulations abruptly reduced the emission of sulfur dioxide from international shipping by about 80% and created an inadvertent geoengineering termination shock with global impact. Here we estimate the regulation leads to a radiative forcing of +0.2±0.11\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$+0.2\\pm 0.11$$\\end{document}Wm−2 averaged over the global ocean. The amount of radiative forcing could lead to a doubling (or more) of the warming rate in the 2020 s compared with the rate since 1980 with strong spatiotemporal heterogeneity. The warming effect is consistent with the recent observed strong warming in 2023 and expected to make the 2020 s anomalously warm. The forcing is equivalent in magnitude to 80% of the measured increase in planetary heat uptake since 2020. The radiative forcing also has strong hemispheric contrast, which has important implications for precipitation pattern changes. Our result suggests marine cloud brightening may be a viable geoengineering method in temporarily cooling the climate that has its unique challenges due to inherent spatiotemporal heterogeneity.

Centennial-scale cooling-induced megadroughts in Myanmar's tropical arid region over the past 8000 years

The future impact of global warming on tropical arid regions is unclear due to uncertainties about the correlation between rising temperatures and changes in precipitation patterns. A critical factor is the reliability of the sedimentary chronologies. Hence, to better understand the potential long-term consequences of climatic warming or cooling for tropical arid regions we compared a pollen record from the annually-laminated sediments of a crater lake in Myanmar with ice core records of the Siberian High, both of which have an annual resolution. Our findings reveal that over the past 8000 years, the Myanmar region experienced six significant drought events, three of which coincided precisely with intensifications of the Siberian High-pressure system. Furthermore, five out of these six events were synchronous with the North Atlantic Bond events within the limit of the dating uncertainties. Conversely, warm periods were associated with increased precipitation along with relatively short-lived drought events. Our findings suggest that regardless of the El Niño intensity, a cooling trend in the Northern Hemisphere may result in persistent extreme drought conditions in arid tropical regions. Therefore, as well as the environmental implications of global warming, it is also important to address the potential hazards associated with cooling, especially in arid tropical regions. To facilitate effective disaster management and to develop strategies for climate change mitigation, it is crucial to better understand the complex relationship between temperature fluctuations and drought. Overall, our findings are a reminder of the importance of not ignoring the potential disasters that may arise from cooling trends while focusing exclusively on warming.

Identification of drought tolerant inbred lines and assessment of combining ability in maize (Zea mays L.)

AbstractMaize is an important agricultural crop ensuring food and nutritional security throughout the globe. It is highly sensitive to many of the biotic and abiotic stresses, and among them, drought is the most severe abiotic stress limiting maize production. Climate change tends to worsen this scenario by changing precipitation patterns and decreasing water availability. Hence, the present study was undertaken to identify drought‐tolerant inbred lines under well‐irrigated and managed stress conditions in the field toward developing drought‐resilient maize hybrids. The initial in vitro screening of 65 agronomically elite maize inbred lines was undertaken at 15%, 20%, and 25% polyethylene glycol (PEG) concentrations. Subsequently, the 15 inbreds selected for their promising performance under varying concentrations of PEG were evaluated in the pot (100%, 60%, and 40% of field capacity [FC]) and managed field experiments (moisture stress). Various physiological, biochemical, and yield attributing traits were measured among the inbreds to assess their drought tolerance potential. The analysis of variance in the pot and field experiments indicated significant genotypic differences among the inbreds and genotype × treatment interaction for different traits considered. In the pot experiment, the phenotypic correlation analysis showed a significant positive association of shoot fresh weight with plant height (r = .71), number of leaves (r = .58), relative water content (r = .60), root fresh weight (r = .58), shoot dry weight (r = .60), and SPAD meter readings under (r = .71) moisture stress condition. In the field experiment, the grain yield had a significant positive association with plant height, relative water content, SPAD before stress, ear length, ear girth, kernel rows per ear, kernels per row, and per day productivity under stress. Proline accumulation in inbreds during stress was found to be higher compared to nonstress conditions. The inbred lines CML 505, CML 444, CML 451, CML 504, QM 11408, and MAI 214 were promising for most of the drought tolerance imparting traits. These six inbreds along with four inbreds having low DRI (SKV 50, MAI E2‐163, MAI 16, and MAI E2‐241) were crossed in half diallel manner, and crosses involving low × high or high × low DRI inbreds showed higher grain yield. The current study also revealed the need of combining various physiological and yield attributing traits in drought breeding programmes.

Shoreline retreat and beach nourishment are projected to increase in Southern California

Sandy beaches in Southern California are experiencing rising coastal erosion due to changes in precipitation patterns and urban growth. As a result, beach nourishment is necessary for mitigation. In our study, we forecast the rates of shoreline retreat and the required volumes of sand nourishment to mitigate it for the coming decades. We employ photogrammetric multi-decadal shoreline positioning and Digital Shoreline Analysis System methods to measure and predict the coastal evolution of the Gulf of Santa Catalina in Southern California. This region is hypothesized to be globally representative of other semi-arid sandy coasts facing similar hydroclimatic and anthropogenic challenges. Our findings indicate that Southern California’s shoreline retreat rates for sandy beaches will increase from the present average value of ~−1.45 to −2.12 meters per year in 2050 and to −3.18 meters per year in 2100. Consequently, the annual volume of sand required for beach nourishment could triple by 2050, increasing from the present-day amount of ~1223 to ~3669 cubic meters per year per kilometer. However, the associated cost for this nourishment will grow five times, exacerbating several coastal communities’ economic and logistical pressures. Similar trends are emerging globally, with semi-arid developing nations already grappling with coastal hazards and may struggle to manage the escalating costs of curbing beach nourishment.

Architecture and history of uranium-bearing Palaeocene–Eocene strata deposited on the eastern margin of the Peri-Tethys (Chu-Sarysu Basin, south Kazakhstan)

Deciphering the facies and architecture of alluvial successions provides invaluable insights into the interplay of tectonics, climate, eustasy, and autogenic processes affecting terrestrial sedimentary systems. The stratigraphic response of fluvial systems to variations in discharge and sediment-supply regimes is now well-understood and is tied to changes in climate, precipitation patterns, or sediment sources. The uraniferous Chu-Sarysu Basin in south Kazakhstan occupies the tectonically stable Turan Platform on the eastern margin of the Peri-Tethys, and the study of its Palaeocene–Eocene sedimentary fill offers an opportunity to unravel eustatic and climatic controls that drove the architecture of reservoirs hosting economically important deposits. The stratigraphic succession comprises two multistorey, laterally extensive, sheet-like sandstone bodies floored by prominent erosion surfaces and interpreted as the deposits of channel belts. These packages are interstratified with floodplain, coastal-wetland, and marine-embayment complexes reflecting major extra-channel belt avulsions and marginal-marine incursions on the low-gradient alluvial plain. The stratal architecture was controlled by changes in accommodation likely induced by well-documented sea-level changes in the Peri-Tethys during the Palaeogene, which permitted the development of a chronostratigraphic framework. Eustatic variations culminated in the widespread flooding of the Turan Platform in the middle Eocene, reflected by transgressive lags above a wave ravinement surface capping terrestrial and marginal-marine deposits. Marked changes in fluvial facies, floodplain styles, and inferred channel planforms between Palaeocene and Eocene strata suggest a climatic overprint on river discharge and sedimentation. Upper Palaeocene meandering channel deposits encased in well-drained floodplain strata are indicative of perennial discharge under a semi-arid climate, whereas lower Eocene low-sinuosity channel fills, displaying evidence for transcritical flows and abundant in-situ vegetation, point to intermittent runoff patterns consistent with a humid and seasonal climate. An evolution in atmospheric moisture at the Palaeocene–Eocene boundary from arid to humid conditions has been reported across the Tethys region, and linked to global climatic perturbations of the Palaeocene–Eocene Thermal Maximum.

CROP IMPROVEMENT THROUGH DIFFERENT MEANS TO ADDRESS CLIMATE CHANGE AND FOOD SECURITY

This study evaluated several crop development techniques in addition to the effects of climate change on productivity in agriculture. Climate affects agricultural productivity and the distribution of crops worldwide. Given the current and projected variations in temperature, precipitation, and carbon dioxide concentrations, it is unclear whether agroecosystems will be able to produce enough food to meet the world's needs. Crop output, water productivity, and soil water balance are frequently altered by climate change. Soil moisture content and groundwater levels will be affected by the immediate effects of global warming-induced changes in temperature and precipitation patterns. Agricultural output is affected by several factors, such as crop variety, growing circumstances, soil deterioration, and water availability. Modern agricultural systems use genetics, biotechnology, plant breeding, environmental monitoring, and adjustments to management techniques to adapt to climate change. On the other hand, without a more thorough approach to agricultural systems, development cannot proceed. A strategy like this would mean growing amounts of a wider variety of superior crops and advancing equity, sustainability, nutrition, and food security in the future.

A Detailed Examination of Türkiye's Projected Precipitation and Growth Season Trends under Climate Change Condition

This study presents a comprehensive analysis of Türkiye's changing precipitation patterns and growing season dynamics in the context of global warming, utilizing the Coupled Model Intercomparison Project Phase 5 (CMIP5) and various Representative Concentration Pathway (RCP) scenarios. In light of global warming, this study provides a thorough analysis of Türkiye's evolving precipitation patterns and growing season dynamics using multiple RCP scenarios and CMIP5. The research aims to fill a crucial gap in climate research by combining historical data and future projections to assess Türkiye's precipitation path under different greenhouse gas emission scenarios. The study employs linear regression for trend analysis and uses data from the Climate Change Knowledge Portal (CCKP), with a focus on precipitation data from 1986 to 2100. According to various RCP scenarios, this study’s findings show a considerable variation in precipitation trends over the 21st century. The RCP 8.5 scenario predicts a significant decrease in precipitation, which would present difficulties for the management of water resources and agricultural productivity. In contrast, the least severe RCP 2.6 pathway shows a fairly stable pattern of precipitation. Complex seasonal hydrological responses to climate change are revealed by monthly precipitation analysis; RCP8.5 predicts an increase in the frequency of periods of drought and heavy precipitation events. The impact of these changes in precipitation on Türkiye's agricultural growing seasons was further investigated in this study. In high-emission scenarios, there was an initial tendency towards longer growing seasons, which were subsequently followed by shorter ones. This suggests that although global warming might initially result in an extended growing season, it might ultimately cause a reduction in it, particularly in situations where mitigation efforts are minimal. The need for adaptable strategies that can respond to long-term climate trends as well as seasonal variability was highlighted by this research. It draws attention to the fact that to mitigate the effects of climate variability, informed policy decisions and integrated resource management are essential. The results highlight the need for quick action to lower the risks associated with water and highlight the potential advantages of intensive mitigation efforts in stabilizing and extending growing seasons.

Disinfection by-product formation potential in response to variability in dissolved organic matter and nutrient inputs: Insights from a mesocosm study

Changes in rainfall patterns driven by climate change affect the transport of dissolved organic matter (DOM) and nutrients through runoff to freshwater systems. This presents challenges for drinking water providers. DOM, which is a heterogeneous mix of organic molecules, serves as a critical precursor for disinfection by-products (DBPs) which are associated with adverse health effects. Predicting DBP formation is complex due to changes in DOM concentration and composition in source waters, intensified by altered rainfall frequency and intensity. We employed a novel mesocosm approach to investigate the response of DBP precursors to variability in DOM composition and inorganic nutrients, such as nitrogen and phosphorus, export to lakes. Three distinct pulse event scenarios, mimicking extreme, intermittent, and continuous runoff were studied. Simultaneous experiments were conducted at two boreal lakes with distinct DOM composition, as reflected in their color (brown and clear lakes), and bromide content, using standardized methods. Results showed primarily site-specific changes in DBP precursors, some heavily influenced by runoff variability. Intermittent and daily pulse events in the clear-water mesocosms exhibited higher haloacetonitriles (HANs) formation potential linked to freshly produced protein-like DOM enhanced by light availability. In contrast, trihalomethanes (THMs), associated with humic-like DOM, showed no significant differences between pulse events in the brown-water mesocosms. Elevated bromide concentration in the clear mesocosms critically influenced THMs speciation and concentrations. These findings contribute to understanding how changing precipitation patterns impact the dynamics of DBP formation, thereby offering insights for monitoring the mobilization and alterations of DBP precursors within catchment areas and lake ecosystems.

Nutrition addition alleviates negative drought effects on Quercus acutissima seedlings

Changing precipitation patterns have exacerbated severe drought events, causing tree die-off and forest mortality. Nutrition addition, as a critical method for forest management, may alleviate negative drought effects. Therefore, we set up a two-factor orthogonal experiment to study the responses of the leaf structural traits of Quercus acutissima to nutrition addition under drought stress. Leaf structural traits, including leaf morphological traits, leaf mass, and leaf nutrition traits, were measured under nine water and nutrition addition treatments. Two-way analysis of variance was used to detect the main effect and interaction of water and nutrition addition on leaf structural traits, principal component analysis was used to screen key traits. Our results show that drought had a unique and decisive effect on leaf length, leaf width, and leaf center, while leaf thickness only depended on nutrition addition. Conversely, no treatments changed the leaf length-width ratio and leaf nitrogen-phosphorus ratio. Besides, nutrition addition alleviated negative drought effects on leaf area, leaf saturated mass, leaf dry mass, leaf nitrogen content, leaf phosphorus content, leaf volume, specific leaf area, and leaf dry-matter content. According to the principal component 1 (54.83%), we screened seven key traits from leaf structural traits, including leaf area, leaf saturated mass, leaf dry mass, leaf nitrogen content, leaf volume, specific leaf area, and leaf dry-matter content, to effectively capture changes in leaf structural traits. Our results demonstrate that under drought stress, nutrition addition enhanced soil nutrition availability, increased leaf nitrogen and leaf phosphorus content, and finally alleviated negative drought effects. Thus, nutrition addition is crucial for plants to get through drought and for forest ecological restoration under global climate change.

Projected Changes in Extreme Precipitation Patterns across Algerian Sub-Regions

Extreme precipitation events play a crucial role in shaping the vulnerability of regions like Algeria to the impacts of climate change. To delve deeper into this critical aspect, this study investigates the changing patterns of extreme precipitation across five sub-regions of Algeria using data from 33 model simulations provided by the NASA Earth Exchange Global Daily Downscaled Climate Projections (NEX-GDDP-CMIP6). Our analysis reveals a projected decline in annual precipitation for four of these regions, contrasting with an expected increase in desert areas where annual precipitation levels remain low, typically not exceeding 120 mm. Furthermore, key precipitation indices such as maximum 1-day precipitation (Rx1day) and extremely wet-day precipitation (R99p) consistently show upward trends across all zones, under both SSP245 and SSP585 scenarios. However, the number of heavy precipitation days (R20mm) demonstrates varied trends among zones, exhibiting stable fluctuations. These findings provide valuable foresight into future precipitation patterns, offering essential insights for policymakers and stakeholders. By anticipating these changes, adaptive strategies can be devised to mitigate potential climate change impacts on crucial sectors such as agriculture, flooding, water resources, and drought.

Effects of nitrogen and water addition on ecosystem carbon fluxes in a heavily degraded desert steppe

Changes in global precipitation patterns and increased nitrogen (N) deposition have important effects on the dynamics of the carbon (C) cycle in grassland ecosystems. Long-term overgrazing caused heavy degradation of grasslands and more than 60 % of China’s natural grasslands experienced moderate to severe degradation. To elucidate the effects of increasing precipitation and N deposition on C fluxes in a desert steppe ecosystem, experiments with nitrogen and water addition were conducted with four treatments, i.e., control (CK), N addition (N), water addition (W), combined addition of N and water (NW), in a Stipa breviflora desert steppe that had been heavily degraded. The ecosystem CO2 fluxes, including gross ecosystem productivity (GEP), net ecosystem CO2 exchange (NEE), and ecosystem respiration (ER), were determined using the closed chamber method during the growing seasons (May–October) of 2019 and 2020. Our results showed that water and nitrogen addition did not change the patterns of the seasonal dynamics of the ecosystem CO2 fluxes, indicating that water is the main limiting factor of CO2 fluxes in the studied desert steppe ecosystem. Precipitation increase (both W and NW treatments) stimulated all three components of the ecosystem CO2 fluxes, but N addition alone enhanced NEE and GEP while had no significant effects on ER, indicating water-induced increase of GEP was caused by both NEE and ER while N-induced increase of GEP was mainly caused by increases of NEE. Water addition can increase the effectiveness of N addition, but there was little interaction between the two factors. Soil moisture was more significantly correlated than soil temperature with ecosystem CO2 fluxes, and water addition could further enhance the correlation of ecosystem CO2 fluxes with soil temperature and moisture. Overall, ecosystem CO2 fluxes are more sensitive to the precipitation increase than to the N addition. These findings indicate that water supply will play more important role in ecosystem productivity of the desert steppe under the predicted scenarios of precipitation increase and increasing N deposition, which also provides scientific evidence for the restoration of those degraded desert steppe induced by overgrazing can not be achieved simply by increasing soil N availability.