Prolonged Drought Research Articles

The Sugarcane ScPetC Gene Improves Water-Deficit and Oxidative Stress Tolerance in Transgenic Tobacco Plants

Water deficit is the main limiting factor constraining sugarcane productivity, and its impact is expected to increase due to climate changes. During prolonged drought periods, most plants become extremely vulnerable to ROS accumulation, which can severely damage their photosynthetic apparatus. The PetC gene, encoding a Rieske FeS protein (ISP), has been shown to regulate the electron transport chain and protect photosystems (PSs) under drought conditions in some plant species. In sugarcane, transcriptome analysis revealed that ScPetC is repressed during drought stress in the field. In this study, we have overexpressed ScPetC in tobacco plants and evaluated its role in water-deficit tolerance. Our results indicate that the ScPetC protein structure is conserved when compared to other species. ScPetC overexpression reduced the negative impact of water deficit on plant development. This effect was associated with a positive impact on ScPetC quantum efficiency and the electron transport rate of PSII, the photosynthetic rate, and water use efficiency. The total chlorophyll content under water deficit was higher in plants overexpressing ScPetC, and this was correlated with less chlorophyll degradation from oxidative damage. Together, these results demonstrate that ScPetC confers tolerance to water deficit and oxidative stresses, making it a candidate gene for crop improvement.

Nexus between Indigenous Knowledge Systems and Adaptation to Climate Change Strategies by Farmers in Kajiado County, Kenya

Indigenous knowledge (IK) has played an important role in adaptation to climate change in traditional agricultural communities. These approaches have been shown to be more effective when integrated with scientifically developed strategies. In this study, a perception survey questionnaire was used to find out whether there is a nexus between IK systems and the uptake of modern Climate Change Adaptation Strategies (CCAS) among farmers in Kajiado County, Kenya. A mixed research approach that involved the use of household questionnaire surveys, key informant interviews, focus group discussions (FGD), and observations was used to obtain data. The two theories, namely the Situated Learning Theory (SLT) and the Theory of Planned Behavior (TPB), formed the basis for illustrating the relationship between variables, while the Model of Private Proactive Adaptation to Climate Change (MPPACC) was the key theoretical model employed. A total of 382 small-scale rural household representatives randomly selected from 3 Kajiado sub-counties were the principal respondents. The key informants included officers in the departments of agriculture, environment, meteorology, trade, and industry, as well as local administration and village elders. Statistical tools such as chi-square, correlation, and binary logistic regression analysis were used to determine associations. Thematic analysis of data collected from key informants and focus group discussions (FGD) was conducted to triangulate the survey results. Farmers' awareness of climate change, risk perceptions of impacts, existing locally developed approaches to climate change adaptation, and perceptions of CCAS were the main areas of investigation. The majority of farmers (85%) indicated that prolonged drought was the main extreme event that affected their farming activities. Of the indicators observed, drought (X2 = 13.861, p =.000) was perceived as the greatest risk associated with climate change to their agricultural productivity. Their IK adaptation strategies resulted from their interactions with the effects of drought on their livelihoods over the years. Farmers who were nomadic (IK practitioners) were not willing to apply for CCAS. For example, they were 72% less likely to increase their irrigated cropped area and 79% less likely to increase the number of better livestock breeds. Among the CCAS approaches, water resource management was the only preferred strategy. This particular finding shows that climate change policies can be easily adopted by indigenous farming communities if they are developed around an issue that matches their socio-ecological priorities. Without taking into account the prevailing social, cultural, and geo-environmental context of specific communities, the adoption of CCAS by farmers would be significantly affected. The study recommends that integrating indigenous agricultural knowledge into climate change adaptation policies enhances community resilience. Aligning adaptation strategies with local responses enriches farmer knowledge and boosts resilience against climate change impacts. Effective climate change adaptation plans should incorporate local weather prediction, environmental conservation, and proven community-based strategies, especially in water resource management for arid and semi-arid pastoralist communities.

Spatiotemporal Variabilities in Evapotranspiration of Alfalfa: A Case Study Using Remote Sensing METRIC and SSEBop Models and Eddy Covariance

Prolonged drought exacerbated by climate change in the Mesilla Valley, one of the major agricultural areas of New Mexico, USA, is causing a shortage of surface water from the Rio Grande for irrigation. Farmers in the Valley are using groundwater for irrigation and complementing it with limited surface water from the river (Rio Grande). Managing irrigation water better is vital to sustaining agriculture in the Valley. Remote sensing (RS)-based crop evapotranspiration (ETa) models offer significant advantages over traditional methods. The ET maps generated by these RS models provide valuable information that can be used to manage irrigation water and crops in water-scarce areas. This study used METRIC and SSEBop RS models to map the ET of alfalfa on a private farm that is managed as commonly practiced in the Valley. The integrated ET values of the two models are compared to those of the ETa measured using the eddy covariance method. The comparison showed that 91.55% of the variability in SSEBop ETa estimates can be explained by the variability in the METRIC ETa estimates, and the variability in eddy covariance ETa can explain 93.07% of the variability in METRIC ETa and 86.01% in the SSEBop Eta estimates. Both METRIC and SSEBop reflected the ETa of alfalfa during full growth and harvesting periods. However, the absolute percent mean relative difference (MRD) of ET was higher for two out of three cuttings by SSEBop (>32%) compared to those for METRIC and eddy covariance. The spatiotemporal variabilities in crop ET estimates using METRIC and SSEBop showed a need to improve on-farm irrigation conveyance and on-the-field irrigation efficiency. Overall, RS models can provide spatiotemporal maps of ET that can be used for decision-making to manage irrigation water better and improve crop yield on a field, farm, and regional scale.

Diel and seasonal mixing patterns and water quality dynamics in a multipurpose tropical semiarid reservoir.

Eutrophication has become a recurrent concern in reservoirs worldwide. This problem is intensified in tropical semiarid regions, where the reservoirs have high seasonal and annual variability of water level and volume. Therefore, an extensive understanding of the diel variation of water quality key-parameters can help improve management of such reservoirs. This study focuses on Castanhão reservoir with the largest multipurpose dam in the Brazilian semiarid. Its main water uses are irrigation, fish farming, and human supply. The reservoir faced a decline in water quality due to a prolonged drought period. While previous research has predominantly emphasized the seasonal dynamics of thermal and chemical stratification, our investigation provides diel assessments of multiple water quality parameters, including nutrient concentrations and phytoplankton abundance. Our primary objective is to compare seasonal and diel variations in stratification and nutrient distribution within the reservoir. Key findings reveal a diel cycle of thermal stratification, primarily during dry season, driven by higher wind speeds. This is corroborated by a significant negative correlation between wind speed and the relative water column stability index. In contrast, during the rainy season, the reservoir experiences continuous thermal stratification due to inflowing water being warmer than the reservoir's water temperature. Notably, a significant negative correlation between total phosphorus and chlorophyll-a, along with a two-fold increase of this nutrient throughout the day during the rainy season, underscores the influence of the phytoplankton community dynamics on the diel nutrient variation. Chemical stratification of dissolved oxygen occurred during dry and rainy seasons, indicating that even during the dry season, where there is no significant inflow, the internal nutrient loading can also significantly impact the water quality of a reservoir. This study advances the understanding of diel water quality dynamics in tropical semiarid reservoirs, shedding light on both climatic and anthropogenic influences on water resources.

Gamma amino butyric acid (GABA) application modulated the morpho-physiological and yield traits of fragrant rice under well-watered and drought conditions

BackgroundChanging climate is causing erratic rainfall and prolonged drought periods, thus posing serious threats to crop productivity. Owing to severity of drought events, it is imperative to take proactive measures to enhance the resilience of drought sensitive crops like rice. Therefore, the present study was carried out to improve the drought stress tolerance in rice through gamma amino butyric acid (GABA) application.MethodsThe experiment was included four GABA concentrations i.e., 0 mM as control, 1 mM, 1.5 mM, and 2 mM, two water levels i.e., 100% and 50% field capacity (referred as FC100 for well-watered and FC50 for drought conditions, respectively), and two fragrant rice cultivars i.e., Super Basmati and Basmati-515.ResultsThe findings unveiled a comprehensive improvement in various parameters with GABA application in fragrant rice under both well-watered (FC100) and water-limited (FC50) conditions, compared to the control. Specifically, GABA induced enhancements were observed in plant height, root length, fresh weight, dry weight, total soluble protein content, and total free amino acid content across both cultivars. Moreover, GABA application significantly improved peroxidase (POD) and catalase (CAT) enzyme activities, alongside elevating anthocyanin levels, while concurrently reducing H2O2 contents in both FC100 and FC50 treatments. Furthermore, the positive impact of GABA extended to morphological traits, with notable increases in panicle length, total tillers and productive tillers per hill, branch and grain numbers per panicle, and 1000-grain weight for Super Basmati and Basmati 515 cultivars under both water regimes, compared to Ck. Similarly, the grain yield increased by 31.01% and 27.32% under FC100 and 36.85% and 27.71% under FC50 in Super Basmati and Basmati-515, respectively, in response to GABA application, compared to Ck. Additionally, principal component analysis (PCA) revealed significant variances attributed to Dim1 and Dim2, with 86.1% and 4.0% of the variance, respectively, across three bi-plots encompassing rice cultivars, water levels, and GABA treatments. Notably, all tested indices, except for H2O2 and non-productive tillers per hill, exhibited positive correlations amongst themselves and with rice yield, further emphasizing the beneficial effects of GABA application on fragrant rice under well-watered and drought conditions.ConclusionsGABA significantly improved fragrant rice performance under both well-watered (FC100) and water-limited (FC50) conditions. Moreover, integrating GABA application into rice cultivation practices could not only improve the crop resilience to drought stress but also potentially benefiting the future food and nutritional security globally. However, however; further research is needed to understand the cellular and molecular mechanisms of the functionality of GABA in fragrant rice, particularly under drought conditions.

Influence of plant growth-promoting bacteria on leaf carbon and nitrogen metabolism of two drought-stressed neotropical tree species: a metabolomic approach.

Deforestation of Atlantic Forest has caused prolonged drought events in the last decades. The need for reforestation is growing, and the development of native seedlings that are more tolerant to drought stress is necessary. A biotechnological tool that improves plant tolerance is the use of plant growth-promoting bacteria (PGPB) as inoculants. Two species of PGPB were inoculated in drought-stressed seedlings of two neotropical tree species that have been used in environmental restoration programs: Cecropia pachystachya and Cariniana estrellensis. Biometrical, physiological, and metabolomic parameters from carbon and nitrogen pathways were evaluated. We found that the PGPB positively influenced photosynthesis and growth parameters in both trees under drought. The enzymes activities, the tricarboxylic acid cycle intermediates, the amino acids, and protein contents were also influenced by the PGPB treatments. The results allowed us to find the specific composition of secondary metabolites of each plant species. This study provides evidence that there is not a single mechanism involved in drought tolerance and that the inoculation with PGPB promotes a broad-spectrum tolerance response in Neotropical trees. The inoculation with PGPB appears as an important strategy to improve drought tolerance in Atlantic Forest native trees and enhance environmental restoration programs' success. MAIN CONCLUSION: The association with plant growth-promoting bacteria improved the tolerance to drought in Neotropical trees through biochemical, physiological, and biometrical parameters. This can enhance the success of forest restoration programs.

Herpetofauna of Laguna Blanca National Park, Argentinean Patagonia: species list and conservation status

Laguna Blanca National Park (LBNP) is located in the mid-west of Neuquén Province, Argentina. It was created in 1940 with the aim of conserving the nesting and breeding habitats of an important diversity of birds. Until now, there have been no exclusive works that address the herpetofauna present. The aim of this article is to provide an updated inventory of reptile and amphibian species in LBNP. We used four sources of information to create the species list: 1) data coming from field observations; 2) specimens deposited in herpetological collections; 3) scientific literature review; 4) online biodiversity databases. We confirm the occurrence of 18 species of herpetofauna in LBNP, including 13 reptiles and 5 amphibians. We also included six species with probable presence according to the range of distribution and habitat similarity. We added the conservation status of the national and international lists for each species. Five species are in some threat category at the national (Vulnerable, Endangered) or international level (Endangered, Critically Endangered). Seven taxa are listed as “Species of Vertebrates of Special Value” by the Administración de Parques Nacionales. Despite being protected within a national park, the herpetofauna present face threats such as prolonged drought events, habitat modification due to the presence of livestock, introduced exotic species, and emerging diseases. Conservation efforts are imperative to protect these species and mitigate their threats.

Impact of Toumeyella parvicornis outbreak in Pinus pinea L. forest of Southern Italy: First detection using a dendrochronological, isotopic and remote sensing analysis

Climate change is expected to affect forests' growth and functioning and to increase their vulnerability to stressors such as prolonged drought and pest outbreaks. Identifying vulnerable forest stands and predicting tree decline is critical for timely management interventions to preserve forests integrity and associated ecosystem services. This study combined dendrochronological and isotopic analyses with satellite remote sensing to detect early warning signs of forest decline in a Pinus pinea L. stand in southern Italy affected by one of the first outbreak of the pine parasite Toumeyella parvicornis reported in Italy. Furthermore, through a comparative study of the analysis techniques, this research aimed to identify the most effective data processing strategies for detecting tree dieback of this species. Satellite analysis revealed a gradual decline in vegetation indices (NDVI, EVI, EVI2) of the stand from 2015 onwards, which coincided with the onset of defoliation due to the pest outbreak. The decline in defoliation intensified in 2020, leading to a severe tree carbon deficit and subsequent mortality of the pine stand in 2023. In comparison, indices such as EVI and EVI2 have been shown to be more sensitive than NDVI in detecting changes in canopy cover. The inclusion of the NDMI index provided important information on the moisture dynamics of the stand. Dendrochronological analyses complemented remote sensing data: a strong decrease in growth was observed from 2020 onwards, undemanding a tipping point for the Pinus pinea stand, which led to tree mortality in 2023. The study highlighted the higher sensitivity of detrended chronologies such as BAI and TRW-I in detecting signs of forest dieback compared to raw tree-ring data. Moreover, intrinsic water use efficiency (WUEi) analysis provided insight into the eco-physiological dynamics underlying pine tree decline, revealing lower tree water retention induced by defoliation. Finally, correlations between growth and WUEi data with meteorological variables highlighted how defoliation increased the vulnerability of trees to the effects of climate, influencing their ability to recover after the pest attack. In conclusion, the combination of these analysis methods provided a detailed and comprehensive overview of tree species dieback due to new invasive pest. Our findings providing valuable insights into the eco-physiological dynamics and early detection of signs of tree decline, useful for planning effective forest management strategies to counteract the diffusion of Toumeyella parvicornis across Italy and Europe.

Test inferences and link function selection in dynamic beta modeling of seasonal hydro-environmental time series with temporary abnormal regimes

We consider the modeling and forecasting of hydro-environmental time series subject to seasonal fluctuations and prolonged droughts. Abnormally dry periods have become more frequent as a result of climate change. We use a class of dynamic beta models which is tailored for doubly-bounded data. We examine two important aspects of this class of models: the accuracy of hypothesis tests based on asymptotic approximations and the choice of link function. In particular, we show that two commonly used tests can yield inaccurate inferences if the estimation of the null model is done on the basis of the maximum number of individual conditional log-likelihoods, and we introduce a new model selection criterion for selecting the model’s link function. Based on tests and the new criterion, we model the useful volumes of three Brazilian hydroelectric power plant water reservoirs. These time series exhibit seasonal fluctuations and contain abnormally dry periods due to intense and prolonged droughts. In-sample predictions and out-of-sample forecasts are produced and compared to those obtained with well known alternative approaches.

Response of the water level of the Balkash Lake to the distribution of meteorological and hydrological droughts under the conditions of climate change

ABSTRACT Hydrological droughts occur due to a variety of hydrometeorological phenomena, such as lack of precipitation, reduced snow cover and high evaporation. The values of these factors vary depending on the climate and the severity of drought events. Droughts caused by a lack of precipitation and continuing in the warm season have a longer periodicity. This important statement raises the question of whether climate change may exacerbate the phenomenon of drought. Therefore, understanding changes in the formation of hydrological droughts is key to foreseeing possible changes in the future. This scientific study analyzes the spread of hydrometeorological droughts in the Ile-Balkash basin using standardized precipitation indices and the drought index of river runoff. Lake Balkash plays an important role in the hydrological cycle and is a valuable freshwater resource, especially in dry years. Prolonged droughts in the area have serious consequences, including deterioration of water quality and loss of wetlands, which are important to the ecological system and migratory birds. The analysis shows that during the period of instrumental observations, several extreme hydrological droughts were observed in this area, (1943–1946, 1973–1975 and 1983–1987), which emphasizes the relevance and importance of scientific research on the problem of drought.

Green hydrogen exports in New Zealand and Chile can improve electricity supply security if configured as local energy insurance

Extreme weather events, for example, prolonged droughts, are increasingly stressing electricity systems and threatening the achievement of energy transition goals. At the same time, countries such as Chile and New Zealand are developing strategies to export renewable energy through green hydrogen. This paper economically evaluates the use of future green hydrogen exports as strategic storage under the logic of energy insurance, based on the assumption that Chile and New Zealand will adopt a hydrogen economy. Our first contribution is to compare the marginal costs of re-electrified green hydrogen, for different scenarios, to the value of lost load in New Zealand and Chile. We then determine the marginal cost of energy produced from green hydrogen based on projected production, transportation, and re-electrification costs for the year 2030. Finally, we estimate the eventual penalties that exporters would incur in the case of breaking their contracts and the overall resulting system costs of using hydrogen for system security. We found that re-electrifying hydrogen can be competitive with conventional technologies at 3 USD/kg. At 1.5 USD/kg, hydrogen is more competitive than fossil fuel-based technologies, for both New Zealand and Chile. Thus, in 2030, it could make economic sense for New Zealand and Chile to use hydrogen as a strategic reserve. The system cost of the proposed insurance scheme in 2030 ranges from 0.53 to 1.76 USD/MWh, which is small compared to total electricity costs. These values can be used for power system expansion and operation planning.

Water Reuse in the Hill Country: Lessons from Existing Reuse Facilities in Texas and Opportunities to Advance Reuse in Comal County

The Greater Edwards Aquifer Alliance outlines the opportunities present in the Texas Hill Country to use recycled water to alleviate the burdens placed on the Edwards and Trinity aquifers by focusing on the present state of recycled water use in Comal County, Texas. The impacts of population growth, prolonged drought, and wastewater disposal on water sources in Comal County are analyzed along with current sources of water reuse to show where recycled water can be utilized effectively. Reclaimed water systems in seven municipalities across Texas are analyzed as case studies to provide examples for further implementation. Water reuse is integral to protecting water supplies and ensuring counties in the Hill Country can adequately protect the health, safety, and quality of life of current and future residents. Water reuse is a vastly underutilized tool in the effort to manage water supplies in the Hill Country, and there are a variety of authorization, financing, and implementation opportunities present in the region to take better advantage of this resource.

KEBIJAKAN FISKAL ZAMAN ABU BAKAR AS-SIDDIQ DAN UMAR BIN KHATTAB

The objective of this article is to elucidate the fiscal policy system and its obstacles during the caliphates of Abu Bakr as-Siddiq and Umar Bin Khattab. In the realm of economics, fiscal policy is a tool for regulating a country's economic system by managing state revenues and expenditures to ensure economic stability and prosperity. This article employs a literature study method. The results indicate that under Abu Bakr, fiscal policy prioritized zakat as the main source of state revenue and included tax collection from non-Muslims. Challenges during his reign included rebellions that disrupted economic activities and groups unwilling to pay zakat, leading to reduced state revenues. Under Umar Bin Khattab's leadership, fiscal policy focused on the development of the Baitul Mal institution, regulation of land ownership, and enforcement of zakat, ushr, khums, non-Muslim alms, kharaj, Fai', and jizyah. All state revenues were allocated for the welfare of Muslims and development projects. A significant economic challenge during Umar's reign was the Ramadah year crisis, caused by a prolonged drought.

Modeling the impacts of extreme climate scenarios on soil acidity (pH and exchangeable aluminum) in Abbay River Basin, Ethiopia

The Abbay River Basin faces the looming threat of extreme climate events, including prolonged droughts and erratic rainfall patterns, which can significantly affect soil health and fertility. This study aimed to explore the influence of extreme climate conditions on soil pH and exchangeable aluminum, aiming to promote sustainable agricultural practices in Ethiopia. The Africa Soil Information Service (ASIS) provided datasets on soil pH and exchangeable aluminum. The European Copernicus Climate Change Data Store was used to download historical and future datasets of extreme climatic indices from 1980 to 2010 and 2015–2050, respectively. The Coupled Model Intercomparison Project Phase 6 model ensemble was used to predict future climate impacts under three shared socioeconomic scenarios: SSP1-2.6, SSP2-4.3, and SSP5-8.5. Data extraction, quality control, and clustering were conducted before analysis, and the model was validated for its accuracy and reliability in predicting soil parameter changes. An artificial neural network model was utilized to predict the effects of extreme climate indices on soil pH and exchangeable aluminum concentrations. The model was designed to accurately and reliably predict changes in soil parameters. This study compared the changes in soil pH and aluminum concentrations using paired t tests. The model's diagnostic results indicated a significant impact of extreme climate scenarios on soil pH and exchangeable aluminum. Extreme climate factors such as heavy precipitation and cooler night time temperatures significantly contribute to soil acidification and an increase in aluminum concentration. Under the SSP1-2.6 and SSP2-4.5 emission scenarios, soil pH levels are expected to increase by 8.38 % and 3.79 %, respectively. These changes in soil pH are expected to have significant impacts on the exchangeable aluminum content in the soil, with increases of 37 % and 5.38 %, respectively, under the same emission scenarios. However, the SSP5.8 scenario predicted a 45 % increase in exchangeable aluminum and a 9.36 % decrease in soil pH. Therefore, this study significantly enhances our understanding of the influence of climate change on soil health. The development of strategies to mitigate climate change impacts on agriculture in the region must consider the effects of extreme climate indices.

Caracterization of the edaphic factor in which within the Straseni forestry entity

The article presents a comparative study of the vegetation conditions (geomorphological aspects, soils) for the central area of the Republic of Moldova (RM) also called „Central Forests”. The prolonged droughts require a different way of managing both forestry and agriculture. Through this study, we aim to identify comparatively the edaphic conditions in 1985 and 2021, how they evolved over time, but also the capacity of the trees to accommodate over time. The forest soils of the Republic of Moldova have been studied less, with the exception of those in the middle of the Republic of Moldova, which also protected areas, have been more often visited with scientific research (A. Ursu 2005).

ANALYSIS OF RAINFALL IN INDONESIA USING A TIME SERIES-BASED CLUSTERING APPROACH

Indonesia has a tropical climate and has two seasons: dry and rainy. Prolonged drought can cause drought disasters, and rain can cause floods and landslides. According to information from the Meteorology, Climatology, and Geophysics Agency (BMKG), natural disasters such as floods and landslides due to heavy rains have been a severe problem in Indonesia for the past five years. Different regional characteristics can affect the intensity of rain that falls in every province in Indonesia. It can be grouped to determine which provinces have similar characteristics to natural disasters due to rainfall. Later, it can provide information to the government and the public so that they are more aware of natural disasters. So, it is necessary to research and classify provinces in Indonesia for rainfall with cluster analysis. The data used is secondary rainfall data taken from the official BMKG website. Cluster analysis of rainfall in 34 provinces in Indonesia used hierarchical and non-hierarchical methods in this study. The approach that is used in this research limits our clustering of the data. Further research with a machine learning approach is recommended. For the clustering method, the agglomerative hierarchical method includes single, average, and complete linkage. The non-hierarchical method includes k-medoids and fuzzy c-means. The cluster analysis results show that the dynamic time warping (DTW) distance measurement method with the average linkage method has the most optimal cluster results with a silhouette coefficient value of 0.813.

Hydrological response of Andean catchments to recent glacier mass loss

Abstract. The impacts of the accelerated glacier retreat in recent decades on glacier runoff changes are still unknown in most Andean catchments, increasing uncertainties in estimating water availability. This particularly affects the outer tropics and Dry Andes, heavily impacted by prolonged droughts. Current global estimates overlook climatic and morphometric disparities, which significantly influence model parameters, among Andean glaciers. Meanwhile, local studies have used different approaches to estimate glacier runoff in a few catchments. Improving 21st-century glacier runoff projections relies on calibrating and validating models using corrected historical climate inputs and calibrated parameters across diverse glaciological zones. Here, we simulate glacier evolution and related runoff changes between the periods 2000–2009 and 2010–2019 across 786 Andean catchments (11 282 km2 of glacierized area, 11° N to 55° S) using the Open Global Glacier Model (OGGM). TerraClimate atmospheric variables were corrected using in situ data, getting a mean temperature bias by up to 2.1 °C and enhanced monthly precipitation. Glacier mass balance and volume were calibrated, where melt factor and the Glen A parameter exhibited significant alignment with varying environmental conditions. Simulation outcomes were validated against in situ data in three documented catchments (with a glacierized area > 8 %) and monitored glaciers. Our results at the Andes scale reveal an average reduction of 8.3 % in glacier volume and a decrease of 2.2 % in surface area between the periods 2000–2009 and 2010–2019. Comparing these two periods, glacier and climate variations have led to a 12 % increase in mean annual glacier melt (86.5 m3 s−1) and a decrease in rainfall on glaciers of −2 % (−7.6 m3 s−1) across the Andes, with both variables comprising the glacier runoff. We confirmed the utility of our corrected regional simulations of glacier runoff contribution at the catchment scale, where our estimations align with previous studies (e.g., Maipo 34° S, Chile) as well as provide new insights on the seasonal glaciers' largest contribution (e.g., La Paz 16° S, Bolivia) and new estimates of glacier runoff contribution (e.g., Baker 47° S, Chile).

Unstable State of Hydrologic Regime and Grain Yields in Northern Kazakhstan Estimated with Tree-Ring Proxies

Changes in the hydrologic regime impose great challenges for grain production. We investigated the impact of dry and wet extremes on the recent losses of crops in Severo-Kazakhstanskaya Oblast (SKO), where 25% of Kazakhstan’s wheat is produced. We reconstructed the Palmer Drought Severity Index (June–August PDSI) and average grain yields (with an explained variance of 48% and 44%, respectively) using five tree ring width chronologies. The extended history of the moisture variability and yields of spring wheat, oats, and barley shows the strong impact of hydrology, rather than the heat, on the grain production. We defined three distinctive hydrologic regimes in SKO: (1) 1886–1942, (2) 1943–1977, (3) 1978–2023. The early regime had fewer drought events, including some that covered a single year. Their duration increased up to 3 years in the second period. The latest regime is an extreme mode of hydrologic variability with events abruptly switching from extremely dry to extremely wet conditions (called “whiplash”). The 21st century regime signifies that the intensified and prolonged decade-long drought transitioned into pluvial condition. The new regime created sizable instability for grain producers. This crop yield reconstruction denotes the potential of the tree-ring proxy for understanding the impact of climate change on the agriculture and food security of Central Asia.

Assessing climatic response and drought resilience in growth of Pinus tabulaeformis Carr. and Tsuga chinensis Pritz. on the southern slope of the Qinling Mountains

Climate anomalies have significant impacts on forest productivity and tree mortality worldwide, leading to ecological disturbances. Understanding the climate-growth relationship and species-specific responses to climate and drought events are crucial for developing effective conservation strategies for tree growth. However, studies on such issues are scarce in the Qinling Mountains (QLM), a significant geo-ecological boundary for climate, vegetation distribution, and river systems in China. This study focuses on the southern slope of the QLM, where we developed tree-ring-width chronologies for Pinus tabulaeformis Carr. and Tsuga chinensis Pritz. in the same habitat, and analyzed their response to climate and two extreme drought events. Both species were found to have a positive correlation with temperature, but their responses to precipitation and scPDSI differed. Specifically, P. tabulaeformis showed a negative correlation with precipitation and scPDSI, while T. chinensis exhibited a positive correlation with precipitation. These differences in response may be attributed to species-specific preferences and interspecific competition between the two coniferous species. Results of the 31-year sliding correlation analysis and K-S test analysis, which aimed to explore the dynamic relationship between chronologies and their most limiting climate factors, demonstrated that both P. tabulaeformis and T. chinensis have experienced a qualitative change in their response patterns to certain climatic factors. Under the backdrop of warming climate, the response of P. tabulaeformis to the maximum temperatures from June to September of the previous year has diminished to a non-response; the response to precipitation from July to September of the previous year, although still significantly negatively correlated, has seen a decrease in significance. In contrast, T. chinensis has exhibited an increasing sensitivity to precipitation from September of the previous year to June of the current year. Study on resistance (Rt), recovery (Rc), and resilience (Rs) of tree growth to drought events revealed that P. tabuliformis and T. chinensis did not exhibit a negative response to the transient drought event in 1933 AD. However, when faced with the prolonged and severe drought event in 1941–1944 AD, both species experienced a decline in growth. It was observed that T. chinensis displayed weaker drought tolerance compared to P. tabuliformis and was more susceptible to the negative impacts of drought conditions. These findings suggest that forest management in the context of climate change should be species-specific, and more effort is needed for species with weaker drought resistance in the QLM, such as T. chinensis.

Improved tomato development by biochar soil amendment and foliar application of potassium under different available soil water contents

The use of carbonaceous materials such as biochar has been considered an innovative solution in agriculture, especially to mitigate dry events caused by climate change. Biochar can improve water holding capacity, physical and chemical properties of soil, and increase the productivity of agricultural systems. However, underlying physiological mechanisms remain poorly understood. Mineral supplementation with potassium nitrate (KNO3) via foliar application is another promising strategy in agricultural management under irrigation deficit. Thus, we investigated the combined effects of biochar and foliar application of KNO3 on growth, yield, and physiology of tomato plants under different irrigation regimes. Results did not indicate a synergistic effect of biochar and foliar application of KNO3. Biochar application alleviated tomato plant stress under deficit irrigation, with plants showing better functioning of photosynthetic apparatus, higher yield, and better fruit quality, as well as increased water use efficiency. Coffee husk biochar (K-rich feedstock) fully met the tomato plant’s demand for K and partially met the demand for some other elements (P, Mg, Fe, Zn, Mn, and Cu). Although positive effects of KNO3 application was verified for some physiological and fruit quality components, overall, foliar application of KNO3 did not improve tomato yield. It is concluded that biochar soil amendment can be a promising practice to increase yield and quality of tomato fruits under deficit irrigation. Therefore, biochar-based fertilizer can be an alternative K source that also provides stable carbon to soil and helps to mitigate stress caused by prolonged drought.