Water Availability Research Articles

Does the response of Rubisco and photosynthesis to elevated [CO2] change with unfavourable environmental conditions?

Climate change due to anthropogenic CO2 emissions affects plant performance globally. To improve crop resilience, we need to understand the effects of elevated CO2 concentration (e[CO2]) on CO2 assimilation and Rubisco biochemistry. However, the interactive effects of e[CO2] and abiotic stress are especially unclear. This study analyses the CO2 effect on photosynthetic capacity under different water availability and temperature conditions in 42 different crop species, varying in functional group, photosynthetic pathway and phenological stage. We analysed close to 3000 data points extracted from 120 published manuscripts. For C3 species, e[CO2] increases net photosynthesis and intercellular [CO2], while reducing stomatal conductance and transpiration. Vmaxc, Rubisco in vitro extractable maximal activity and content also decrease with e[CO2] in C3 species, while C4 crops are less responsive to e[CO2]. The interaction with drought and/or heat stress does not significantly alter these photosynthetic responses, indicating that the photosynthetic capacity of stressed plants responds to e[CO2]. Moreover, e[CO2] has strong effect on the photosynthetic capacity of grasses mainly in the final stages of development. This study provides insight into the intricate interactions within the plant photosynthetic apparatus under the influence of climate change, enhancing the understanding of mechanisms governing plant responses to environmental parameters.

Be prepared: how does discontinuous hydration in Tabebuia heterophylla seeds induce stress tolerance in seedlings?

Discontinuous hydration and dehydration (HD) cycles refer to controlled imbibition followed by dehydration before seed germination. Here, we investigated whether the level of imbibition before HD cycles affects the physiology of Tabebuia heterophylla seeds and seedlings. Seeds were imbibed for 10 h (T1; phase I of imbibition) or 35 h (T2; phase II), dehydrated, and progressively rehydrated one to four times (HD cycles). Germination and biochemical parameters (membrane integrity; total soluble, reducing, and nonreducing (NRS) sugars; proteins, amino acids, proline, H2O2, catalase, ascorbate peroxidase, and glutathione reductase activity) were quantified at the last rehydration step of each cycle. Biometric and biochemical parameters (including pigments) were analysed in seedlings 60 days after germination. HD cycles at T1 led to reduced seed germination and greater plasma membrane damage, higher enzyme activity (catalase and glutathione reductase) and accumulation of NRS, total amino acids, and proline compared to the controls and T2 treatment. Cellular damage became more severe with more HD cycles. HD cycles at T2 synchronized germination regardless of the number of cycles and also had a priming effect. T2 seeds had less NRS, total amino acids, and proline content than T1. HD cycles at T1 produced seedlings with higher carotenoid and total chlorophyll content than controls and T2, while seedlings from HD cycles at T2 had higher amounts of osmoprotectants. HD cycles at T2 benefited seeds and seedlings more than at T1. This suggests that the physiological and biochemical effects of HD cycles in seeds modulate seedling plasticity, depending on water availability, potentially promoting increased tolerance to recurrent droughts that will be intensified with ongoing climate changes.

GIS-based method for assessing the viability of solar-powered irrigation

To attain food security, sub-Saharan Africa needs to increase its use of irrigation to improve agricultural productivity and resilience to climate change-induced droughts and erratic rain patterns. Stand-alone solar-powered irrigation systems are a promising technology to power irrigation where grid electrification is unavailable. However, these systems’ economic viability and sustainability are affected by spatially varying factors such as climate, water availability, and solar potential, making it challenging to plan their roll-out. This study addresses the planning challenge by developing a novel open-source reproducible geospatial methodology to determine irrigation water demand, peak power demand, life cycle cost, and locations where solar-powered irrigation systems would be cheaper than alternative off-grid irrigation technologies. The method considers spatial–temporal data for meteorological conditions, soil quality, water distance and depth, solar resource potential, technology efficiency and local equipment and fuel costs. Maize cultivation in Kenya is taken as a case study to demonstrate the method. We find the median peak irrigation water demand in Kenya to be 65,000 l/ha/day and the median peak power demand to be 2.6 kW/ha. The levelized cost of solar-powered irrigation systems ranges from US$ 0.09/kWh to US$ 0.25/kWh, making solar irrigation cheaper than diesel-powered irrigation in all Kenyan regions. The results from the method offer valuable insights to governments, farmers and investors on where water use regulations are required for sustainable water use, where subsidies and innovative financial models are needed for the affordability of solar irrigation and where alternative uses of energy from the solar systems beyond irrigation are possible.

Impact of graphene incorporation on the oxygen evolution reaction of Co-Fe-based electrocatalysts synthesized via one-step electrodeposition

The oxygen evolution reaction (OER) presents a major challenge for water splitting due to its slow kinetics. In this study, Co-Fe-Gr nanocomposite coatings were developed on carbon steel via electrodeposition using graphene (Gr) at concentrations of 0.02, 0.04, and 0.06 g/L to enhance OER performance. The sample with 0.02 g/L Gr exhibited a unique cauliflower-like morphology with aligned cobalt, as revealed by FE-SEM, leading to an increased electrochemical surface area. This optimal nanocomposite (Co-Fe-Gr (0.02 g/L)) demonstrated a low overpotential of 88 mV at 10 mA cm2, high stability (4.2 mF cm⁻2), and low resistance (R = 7.5 Ω cm⁻2). Additionally, it showed a small Tafel slope of 6.6 mV/dec and maintained stability after 12 h. A turnover frequency (TOF) of 73.6 s⁻1 indicated that graphene doping significantly reduced the adsorption energy of intermediates, greatly enhancing OER activity for efficient water splitting applications.

Evaluation of Mediterranean perennials for extensive green roofs in water-limited regions: A two-year experiment

Extensive green roofs (EGRs) play a crucial role in urban environments, offering numerous environmental, economic, and social benefits. However, their performance largely depends on plant selection and adaptation to local climatic conditions. This study investigates the suitability of six perennial Euro-Mediterranean species for EGRs in Mediterranean and semi-arid regions, under different water regimes. A two-year experimental analysis was conducted in Rome (Italy) assessing flowering and mortality rates. Results revealed species-specific responses to irrigation levels, with notable performances observed in Thymus serpyllum, Saponaria ocymoides, and Teucrium chamaedrys, showcasing resilience to water stress. Conversely, Lavandula stoechas and Cerastium tomentosum exhibited sensitivity to water availability, emphasizing the importance of species selection for EGRs. No species completely adhered to the expected flowering period, but showed a general tendency of anticipation, and sometimes an extended flowering period, with some differences between the species. The study underscores the complexity of plant-environment interactions and highlights the need for diversified species composition to enhance EGR functionality and resilience.

Effect of rock phosphate direct application on tropical legumes under different soil types of Sudan Savanna

ABSTRACT Direct application of low-grade rock phosphate (RP) is a less expensive alternative than the application of chemical phosphorus (P) for small holders relying on nutrient-deficient weathered soils. However, the effect of RP application on growth and yield is unstable for different crop species and soil water conditions. To identify legume species effective for RP direct application, five tropical legumes (cowpea, groundnut, bambara nut, mung bean, and soybean) were tested under two soil types with different water-holding capacities in Sudan Savanna; Lixisols and Plinthosols. The experiment was conducted under three conditions of P treatment, namely, RP application, triple super phosphate (TSP) application, and no phosphorus fertilizer application (0P). Under RP treatment, higher grain yield was obtained in Lixisols, which had a higher water-holding capacity. However, the yield increase was suppressed in the year with more rainfall owing to drastic changes in the soil moisture content, which caused excessive soil moisture stress during vegetative growth periods. Among the five legume species, cowpea and groundnut showed higher grain yields under the RP treatment than did other species. RP application increased shoot biomass but caused small changes in the shoot P and N concentrations. Soybean in Plinthosols had the highest yield ratio of RP/0P, but the absolute yield was low because of the insufficient soil water availability caused by the low water-holding capacity. RP direct application can assist shoot growth and yield, but it rarely compensates for basal yield differences between soil types and among legume species.

Physicochemical and sensory quality of high antioxidant fruit leather of red dragon fruit and watermelon rind enriched with seaweed

Fruit, as a source of antioxidants and phenolic compounds, is perishable. It also has an underutilized component. Fruit leather has a long shelf life in the form of thin sheets with a distinctive texture. This study aimed to investigate the effect of seaweed (Eucheuma cottonii) addition on the physicochemical and sensory quality of fruit leather made from the combination of red dragon fruit and watermelon rind. The physicochemical quality was characterized by measuring the critical quality parameters of fruit leathers, including proximate analysis, water activity, total phenol, antioxidant activity, texture, and organoleptic analysis. The statistical analysis of phenolic compound activity, antioxidant activity, vitamin C, moisture content, carbohydrates, and water activity (aw) was conducted using a one-way ANOVA test, while the analysis of ash content, protein, fat, tensile strength, elongation, and organoleptic properties was performed using the Kruskal–Wallis test. Increasing seaweed concentration significantly increased moisture, ash, protein, vitamin C, total phenol, water activity, and elongation but decreased fat content. Furthermore, the increase in seaweed concentration reduced liking toward taste and color significantly but increased texture liking. The best product was the F2 product with 10% seaweed. F2 has the following attributes: 11.07% of moisture content, 2.34% of ash, 1.53% of protein, 0.19% of fat, 84.86% of carbohydrate, 8.17 mg/100 g of vitamin C, 0.41 of water activity, 0.54 N/m2 of tensile strength, 22.22% of elongation, 107.39 ppm of IC50, 1.66 mg/GAE g of total phenolics.

Effect of the Bioprotective Properties of Lactic Acid Bacteria Strains on Quality and Safety of Feta Cheese Stored under Different Conditions

Lately, the inclusion of additional lactic acid bacteria (LAB) strains to cheeses is becoming more popular since they can affect cheese’s nutritional, technological, and sensory properties, as well as increase the product’s safety. This work studied the effect of Lactiplantibacillus pentosus L33 and Lactiplantibacillus plantarum L125 free cells and supernatants on feta cheese quality and Listeria monocytogenes fate. In addition, rapid and non-invasive techniques such as Fourier transform infrared (FTIR) and multispectral imaging (MSI) analysis were used to classify the cheese samples based on their sensory attributes. Slices of feta cheese were contaminated with 3 log CFU/g of L. monocytogenes, and then the cheese slices were sprayed with (i) free cells of the two strains of the lactic acid bacteria (LAB) in co-culture (F, ~5 log CFU/g), (ii) supernatant of the LAB co-culture (S) and control (C, UHT milk) or wrapped with Na-alginate edible films containing the pellet (cells, FF) or the supernatant (SF) of the LAB strains. Subsequently, samples were stored in air, in brine, or in vacuum at 4 and 10 °C. During storage, microbiological counts, pH, and water activity (aw) were monitored while sensory assessment was conducted. Also, in every sampling point, spectral data were acquired by means of FTIR and MSI techniques. Results showed that the initial microbial population of Feta was ca. 7.6 log CFU/g and consisted of LAB (>7 log CFU/g) and yeast molds in lower levels, while no Enterobacteriaceae were detected. During aerobic, brine, and vacuum storage for both temperatures, pathogen population was slightly postponed for S and F samples and reached lower levels compared to the C ones. The yeast mold population was slightly delayed in brine and vacuum packaging. For aerobic storage at 4 °C, an elongation in the shelf life of F samples by 4 days was observed compared to C and S samples. At 10 °C, the shelf life of both F and S samples was extended by 13 days compared to C samples. FTIR and MSI analyses provided reliable estimations of feta quality using the PLS-DA method, with total accuracy (%) ranging from 65.26 to 84.31 and 60.43 to 89.12, respectively. In conclusion, the application of bioprotective LAB strains can result in the extension of feta’s shelf life and provide a mild antimicrobial action against L. monocytogenes and spoilage microbiota. Furthermore, the findings of this study validate the effectiveness of FTIR and MSI techniques, in tandem with data analytics, for the rapid assessment of the quality of feta samples.

Exploring oligosaccharide effects on wheat starch gelatinization: Mechanisms and oligosaccharide structural perspectives

Controlling the gelatinization of starch is vital for achieving desired food design, and sugars and oligosaccharides (OSs) have a significant impact on the gelatinization temperature (Tgel) of starch. This study delved into the effects of sucrose, maltotetraitol, and ten glucose-based OSs with different glycosidic linkage patterns, degrees of polymerization (DP), and linear or cyclic structures on the Tgel of wheat starch. The objective of this study was to uncover the underlying mechanisms by which OSs alter Tgel to support the design and use of OSs for sugar reduction in baked goods. Findings underscore the notable impact of both OS concentration and type on Tgel. Increases in OS concentration resulted in Tgel elevation, closely linked to changes in water activity and effective water volume fraction (φw,eff). Among the same DP OSs, a higher effective number of hydroxyl groups available for hydrogen bonding per unit volume of the solute (NOH,S/Vs) corresponded to increased Tgel, indicating higher hydroxyl density in OSs leads to an increased number of hydrogen bond formation between OSs and starch that stabilizes the structure. Of particular note is that isomaltose (α-1,6 linkage) significantly elevated the Tgel more than the other DP2 OSs, trehalose (α-1,1 linkage), kojibiose (α-1,2 linkage), and maltose (α-1,4 linkage), even with low NOH,S/Vs. This underscores the importance of OS structural flexibility in antiplasticizing starch. The study enriches our understanding of how OSs influence starch Tgel relative to the effects of sucrose, emphasizing the roles of intermolecular hydrogen bonding and OS structural flexibility in elevating starch Tgel in a manner which is beneficial for maintaining the texture and structural properties of reduced-sugar baked goods.

Impacts of Wildfires on Groundwater Recharge: A Comprehensive Analysis of Processes, Methodological Challenges, and Research Opportunities

Increasing wildfire activity has led to complex ecosystem consequences, with direct effects on the subsystems that affect the presence and movement of water. Although studies have investigated the cascading effects of wildfires on the water balance, our understanding of broad-scale groundwater modifications post fire remains unclear. This review aims to elucidate fire-induced shifts in the water balance, their causal factors, and their potential effects on groundwater recharge. By scrutinizing prior research examples that modeled post-fire recharge scenarios, the review highlights persistent knowledge gaps. The challenge of quantifying and integrating fire-induced alterations in precipitation, wind, and land temperature patterns into recharge projection models is specifically addressed. Despite these gaps, post-fire values of hydrologically meaningful parameters such as leaf area index (LAI), curve number (CN), and near-surface saturated hydraulic conductivity (KST) have been identified. Simulating post-fire recharge via the extrapolation of these values requires the consideration of site-specific conditions, vegetation recovery, and ash removal. It frequently results in a reduced interception and increased surface runoff, while evapotranspiration remains dependent on site-specific factors and often dictates groundwater recharge estimates. Although post-fire recharge simulations are inherently complex and imprecise, their growing application can guide land-use alterations and support policy implementation that considers fire-induced water availability changes.

Global Distribution of Mammalian Cradles and Museums is Driven by Past Climate Dynamics and Present Water–Energy Balance

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

Growing the portfolio: circular economy through water reuse in Iran

In Iran, water scarcity is increasing due to the rapid growth in economy and population, but also due to waste and overuse. Marginal water resources (unutilized water of lower quality) can provide important options to augment water supply or replace freshwater use. In this way, they can reconcile the seemingly opposing views of water development and water management. Encouraging reuse and circulation of marginal water can enhance water availability and conserve freshwater. This paper analyses water reuse options and policies in Iran. It explains policy constraints based on the type of water for reuse and compares the water reuse policies in Iran to regional experiences. Such a contextualization of Iran’s policies from a regional perspective provides opportunities for mutual learning and lessons for policy reforms. For Iran, there is a need for investments and comprehensive reuse policies. New water sources need to be appropriately identified, treated, delivered and accepted by end-users and society.

High-Capacity Zinc Anode Enabled by a Recyclable Biomass Bamboo Membrane Separator.

Aqueous zinc ion batteries have gained attention as viable energy storage systems, yet the occurrence of detrimental side reactions and Zn dendrite formation undermines the efficiency of Zn anodes. Controlling water activity have proven to be an effective strategy in mitigating these challenges. However, strategies such as electrolyte design and electrode protection layer show weakness to varying degrees. Here, a new oxygen-functionalized biomass bamboo membrane separator (denoted as BM) is proposed to restrain the activity of water molecules. This BM separator features a unique, multi-tiered 2D interlayer that facilitates rapid ion diffusion. Additionally, the oxygen functional groups of the BM separator can form hydrogen bonds with water molecules, effectively transforming water molecules from a free state to a bound state. Consequently, the Zn/Zn asymmetric coin cell using BM can work at the ultrahigh rate and capacity of 30 mA cm-2 and 30mAhcm-2 for more than 80h while its counterparts using glass fibercan barely work. Moreover, full cells using BM separator exhibited a capacity retention of 89.7% after 1000 cycles at 10Ag-1. This study reveals the important influence of water-limited activity on Zn anode protection and provides an avenue for the design of novel separator.

Beyond the Border: Exploring the Complex Dynamics of Water Tensions Between India and China

This paper explores the historical context and current dynamics of the transboundary water issues between India and China. Both countries share multiple transboundary river basins, with the Brahmaputra River being one of the most significant. The importance of the Brahmaputra River to both nations goes beyond just providing resources. It has implications for national security, regional stability, and human livelihoods. However, China's upstream control over the river and its extensive dam-building projects have raised concerns in downstream India and Bangladesh about potential impacts on water availability, agriculture, and livelihoods. The river system is critical for the socioeconomic well-being of millions of people, yet the competing demands for water resources have led to geopolitical tensions. The paper highlights China's strategic use of water resources, including plans for large-scale dams, which India views as a potential threat to its water security. It also underscores the importance of a nuanced understanding of hydropolitics, emphasizing the need for human security, particularly water security, in addressing these challenges. It argues that while "water wars" are unlikely, "water tensions" are significant and must be addressed through comprehensive bilateral agreements and collaborative efforts.

Magma storage conditions of Lascar andesites, central volcanic zone, Chile

Abstract. Lascar volcano, located in northern Chile, is among the most active volcanoes of the Andean Central Volcanic Zone (CVZ). Its activity culminated in the last major explosive eruption in April 1993. Lascar andesites which erupted in April 1993 have a phase assemblage composed of plagioclase, clinopyroxene, orthopyroxene, Fe–Ti oxides, and rhyolitic glass. To better constrain storage conditions and mechanisms of magmatic differentiation for andesitic magmas in a thick continental crust, crystallization experiments were performed in internally heated pressure vessels at 300 and 500 MPa, in the temperature (T) range of 900–1050 °C, at various water activities (aH2O) and oxygen fugacities (logfO2 between QFM+1.5 and QFM+3.3 at aH2O =1; QFM is quartz–fayalite–magnetite oxygen buffer). The comparison of experimental products with natural phase assemblages, phase compositions, and whole-rock compositions was used to estimate magma storage conditions and to reconstruct the magma plumbing system. We estimate that Lascar two-pyroxene andesitic magmas were stored at 975±25 °C, 300±50 MPa, and logfO2 of QFM+1.5±0.5, under H2O-undersaturated conditions with 2.5 wt % to 4.5 wt % H2O in the melt. The geochemical characteristics of the entire suite of Lascar volcanics indicates that a fractionating magmatic system located at a depth of 10–13 km is periodically replenished with less evolved magma. Some eruptive stages were dominated by volcanic products resulting most probably from the mixing of a mafic andesitic magma with a felsic component, whereas compositional variations in other eruptive stages are better explained by crystal fractionation processes. The relative importance of these two mechanisms (mixing vs. crystal fractionation) may be related to the amount and frequency of magma recharge in the reservoir.

Physicochemical and microbiological analyzes of Tetragonisca angustula, Melipona mondury and Scaptotrigona postica honey from the first public meliponary in Marília City (São Paulo – Brazil)

Native stingless bees (NSBs) are widely distributed in Brazilian territory. They are responsible for pollinating plants, maintaining biodiversity, and producing honey, a natural and therapeutic sweetener, used by different populations. This study aimed to identify physical, chemical, and microbiological characteristics of honey samples collected during the first harvesting of Tetragonisca angustula, Melipona mondury, and Scaptotrigona postica bees kept in the first public meliponary situated in Marília, São Paulo state, Brazil. Samples were collected directly from NSB’s hives in the meliponary and sequentially matured in plastic bottles with airlock valves, duringn 90 days, in the Physicochemical Analyzes Laboratory at Fatec Marília. Subsequently, analyzes were carried out to determine pathogenic and spoilage microorganisms. In addition, analyzes to determine free acidity, reducing sugars, total soluble solids, apparent sucrose, humidity, insoluble solids, pH, water activity, and hydroxymethylfurfural were performed. Results showed the presence of molds and yeasts. Nevertheless, because the values agreed with the current legislation and the pathogenic and deteriorating contaminants were absent in the honey samples, one may suggest that they were brought to the hive by bees, since floral nectaries are their normal habitats. The physicochemical parameters, with the exception of reducing sugars, agreed with other scientific studies and reinforced the proposal for technical regulation, considering the absence of specific national legislation for NSB’s honey. Therefore, it is considered relevant to establish regulations for NSB’s honey to define identity and standard requirements to guarantee safe consumption and direction for scientific studies in the area.

Evaluation of Pedotransfer Functions to Estimate Soil Water Retention Curve: A Conceptual Review

The soil water retention curve (SWRC) is a vital soil property used to evaluate the soil’s water holding capacity, a critical factor in various applications such as determining soil water availability for plants, soil conservation and management, climate change adaptation, and mitigation of flood risks. Estimating SWRC directly in the field and laboratory is a time-consuming and laborious process and requires numerous instruments and measurements at a specific location. In this context, various estimation approaches have been developed, including pedotransfer functions (PTFs), over the past three decades to estimate soil water retention and its associated properties. Despite the efficiencies, PTFs and semi-physical approach-based models often have several limitations, particularly in the dry range of the SWRC. PTFs-based modeling has become a key research topic due to readily available soil data and cost-effective methods for deriving essential soil parameters, which enable more efficient decision-making in sustainable land-use management. Therefore, advancement and adjustment are necessary for reliable estimations of the SWRC from readily available data. This article reviews the evaluation of the current and past PTFs for estimating the SWRC. This study aims to evaluate PTF techniques and semi-physical approaches based on soil texture, bulk density, porosity, and other related factors. Additionally, it also assesses the performance and limitations of various common semi-physical models proposed and developed by Arya and Paris, Haverkamp and Parlange, the Modified Kovács model by Aubertin et al., Chang and Cheng, Meskini-Vishkaee et al., Vidler et al., and Zhai et al. This assessment will be effective for researchers in this field and provide valuable insight into the importance of new PTFs for modeling SWRC.

Assessment of groundwater quality and its vulnerability for safe drinking purpose

ABSTRACT Groundwater is a main resource of drinking water in several parts of India. Its degradation poses a significant risk to water availability and human health, highlighting the importance of regularly evaluating groundwater quality in these regions. Thus, the significant aim of this study is to examine and map groundwater quality and its vulnerability for drinking purposes using the EWQI, PIG, and GOD methods. The quality of groundwater in the study area is found to be generally alkaline in nature. More than 20% of samples exceeded the desirable limit of TH. Correlations of major ions revealed that groundwater samples were distributed in the areas of silicate weathering and dolomite dissolution. The EWQI values vary from 33.74 to 62.22, with an average value of 41.54. The spatial distribution diagrams of hydrochemical parameters and EWQI represent poor water quality in southern and southern-western areas. The PIG ranged from 0.49 to 0.84, with an average value of 0.59. Moreover, the GOD method indicates that the southern part of the region has moderate vulnerability and demonstrates that groundwater level is the significant factor for the calculation of groundwater vulnerability.

Seed functional ecology in Brazilian rock outcrop vegetation: an integrative synthesis.

Rock outcrop vegetation is distributed worldwide and hosts a diverse and unique flora that evolved under harsh environmental conditions. Unfortunately, seed ecology in such ecosystems has received little attention, especially regarding seed traits, germination responses to abiotic factors and the potential role of phylogenetic relatedness on such features Here, we provide the first quantitative and phylogenetically-informed synthesis of the seed functional ecology of Brazilian rock outcrop vegetation, with a particular focus on quartzitic and ironstone campo rupestre. Using a database of functional trait data, we calculated the phylogenetic signal of seven seed traits for 371 taxa and tested whether they varied among growth forms, geographic distribution, and microhabitats. We also conducted meta-analyses that included 4,252 germination records for 102 taxa to assess the effects of light, temperature, and fire-related cues on the germination of campo rupestre species and explored how the aforementioned ecological groups and seed traits modulate germination responses. All traits and germination responses showed a moderate-to-strong phylogenetic signal. Campo rupestre species responded positively to light and had maximum germination between 20-25 ºC. The effect of temperatures beyond this range was moderated by growth form, species geographic distribution, and microhabitat. Seeds exposed to heat shocks above 80 °C lost viability, but smoke accelerated germination. We found a moderating effect of seed mass for in responses to light and heat shocks, with larger, dormant seeds tolerating heat better but less sensitive to light. Species from xeric habitats evolved phenological strategies to synchronise germination during periods of increased soil water availability. Phylogenetic relatedness plays a major role in shaping seed ecology of Brazilian rock outcrop vegetation. Nevertheless, seed traits and germination responses varied significantly between growth forms, species geographic distribution and microhabitats, providing support to the regeneration niche hypothesis and the role of functional traits in shaping germination in these ecosystems.

Local neighborhood affects stem rehydration under drought: evidence from mixtures of European beech with two different conifers.

Mixed-species forests are, for multiple reasons, promising options for forest management in Central Europe. However, the extent to which interspecific competition affects tree hydrological processes is not clear. High-resolution dendrometers capture sub-daily variations in stem diameter; they can simultaneously monitor stem growth (irreversible changes in diameter) and water status (reversible changes) of individual trees. Using the information on water status, we aimed to assess potential effects of tree species mixture, expressed as local neighborhood identity, on night-time rehydration and water stress. We deployed 112 sensors in pure and mixed forest stands of European beech, Norway spruce, and Douglas fir on four sites in north-western Germany, measuring stem diameter in 10-minute intervals for a period of four years (2019-2022). In a mixture distribution model, we used environmental variables, namely soil matric potential, atmospheric vapor pressure deficit, temperature, precipitation, and neighborhood identity to explain night-time rehydration, measured as the daily minimum tree water deficit (TWDmin). TWDmin was used as a daily indicator of water stress and the daily occurrence of sufficient water supply, allowing for stem growth (potential growth). We found that species and neighborhood identity affected night-time rehydration, but the impacts varied depending on soil water availability. While there was no effect at high water availability, increasing drought revealed species-specific patterns. Beech improved night-time rehydration in mixture with Douglas fir, but not in mixture with spruce. Douglas fir however, only improved rehydration at a smaller share of beech in the neighborhood, while beech dominance tended to reverse this effect. Spruce was adversely affected when mixed with beech. At species level and under dry conditions, we found that night-time rehydration was reduced in all species, but beech had a greater capacity to rehydrate under high to moderate soil water availability than the conifers, even under high atmospheric water demand. Our study gives new insights into neighborhood effects on tree water status and highlights the importance of species-specific characteristics for tree-water relations in mixed-species forests. It shows that drought stress of European beech can be reduced by admixing Douglas fir, which may point towards a strategy to adapt beech stands to climate change.