A critical review on the active anti-viral metabolites of bioprospecting traditionally used plant species from semi-arid regions of the subcontinent.

Plants are crucial medicinal resources, with 80 % of people relying on them for primary healthcare. The search for natural antiviral compounds is increasing, especially in semi-arid ecosystems where abiotic stress promotes the production of beneficial secondary metabolites. This review highlights semi-arid plants with the potential as functional foods to combat viral diseases and other illnesses. Literature was searched in databases like ScienceDirect to gather information on novel compounds from stress-tolerant semi-arid plant species. These compounds have potential uses in treating viral infections and other health issues such as diabetes and high blood pressure. The review screened 61 semi-arid plants known for their antiviral metabolites. Eight plants were identified with novel antiviral compounds. Key metabolites include agathisflavone, pectic arabinogalactan, azadirachtin, aloin, aloe-emodin, aloesaponarin I, allicin, terpenoids, chlorogenic acids, curcumin, chromones, ß-sitosterol, lupeol, oleuropein, carissol, ß-amyrin, and ∆-9-tetrahydrocannabinol. Stress-tolerant semi-arid plants are significant sources of metabolites for treating infectious diseases and boosting immune systems. Further research on these metabolites in animal models is needed to verify their efficacy for treating human diseases during endemic and pandemic outbreaks, such as COVID-19.

Examining the complex dynamics influencing acute malnutrition in Turkana and Samburu counties: Study protocol.

Acute malnutrition in children under 5 years is persistent in Eastern Africa's arid and semiarid lands. This study aimed to identify the drivers of acute malnutrition in Turkana and Samburu counties, Kenya. This was a population-based longitudinal mixed-methods observational study. Qualitative and quantitative data were collected at Wave 1, but only quantitative data were collected during follow-up. Participants were a representative sample of children and their primary caregivers from households with children under 3 years at Wave 1. Anthropometric measurements of all children under 5 years in the sampled households were taken at Wave 1 (May to July 2021), and one child under 3 years was randomly selected for follow-up about every 4 months over 2 years for six data collection waves. The study also collected data on sociodemographics; child feeding practices and morbidity; household water and food insecurity; shocks; coping strategies, social safety nets and economic safeguards; water, sanitation and hygiene; women's decision-making and food consumption. Qualitative data were collected through community dialogues, focus group discussions, in-depth interviews, photovoice and key informant interviews with mothers and fathers with children under 5 years, community leaders, county officials and staff of nongovernmental organisations. Data collection is complete and analysis is ongoing. The analysis includes thematic analysis of qualitative data and descriptive and multi-variable regression analyses of quantitative data.

Diversity Patterns of Plant Communities along an Elevational Gradient in Arid and Semi-Arid Mountain Ecosystems in China.

Quantitative classification and ordination are instrumental in improving our understanding of plant community patterns and facilitating effective conservation efforts in national mountain ecosystems worldwide. However, there has been a lack of relevant research focused on arid and semi-arid mountain ecosystems. This study aims to address this gap by investigating the Ningxia Helan Mountain National Nature Reserve (located in Northwest China). We conducted a comprehensive study on the patterns of plant communities and their association with environmental factors across a broad elevation range from 1200 m a.s.l. to 2600 m a.s.l. Our findings revealed the presence of 121 angiosperm species across 41 families, with vegetation classified into six distinct groups through two-way indicator species analysis (TWINSPAN) along the elevational gradient. Notably, the communities of Ulmus, Prunus, and Stipa in the middle elevation range exhibited the highest Shannon-Wiener (SW) and Simpson (SN) diversity indices, and these indices followed a single-peak pattern with increasing elevation. Canonical correspondence analysis (CCA) further revealed six distinct yet interrelated plant communities, revealing elevation (ELE) and the biological aridity index (BK) as the most influential environmental factors influencing plant communities' distribution. This understanding is critically important for biodiversity conservation and the management of ecosystems in arid and semi-arid mountain ecosystems.

Road corridors vegetation in the semi-arid region: functional trait diversity and dynamics.

Road corridor vegetation plays a vital role in maintaining ecosystem stability and providing essential ecological services, particularly in semi-arid regions where environmental conditions are challenging. In this study, we investigated the functional traits of native and non-native plant species along the N5 highway corridor in the semi-arid region of Punjab, Pakistan. The methodology involved extensive field surveys and systematic sampling of herbaceous vegetation, followed by detailed measurements of functional traits diversity. We classified 38 plant species into native and non-native categories and analyzed their distribution, life forms, leaf spectra, and flowering phenology. Our results revealed distinct patterns in the functional traits of native and non-native species, with non-native species exhibiting larger plant heights, leaf sizes, and leaf surface areas compared to native species. Additionally, native species displayed greater root and stem biomass, indicative of adaptations to nutrient-poor soils and water-limited environments. The findings suggest that non-native species possess traits associated with rapid growth and resource acquisition, enabling them to outcompete native vegetation and establish dominance in roadside ecosystems. These results provide valuable insights for understanding the ecological implications of non-native species and designing effective management strategies to mitigate their impacts on native biodiversity and ecosystem resilience in semi-arid regions.

Ulva lactuca blooms through the eyes of fishers: Threats to vulnerable coastal communities.

Eutrophication intensifies Harmful Macroalgae Blooms (HMBs) in coastal environments, reducing habitat suitability for organisms and creating significant challenges for small-scale artisanal fishers. Leveraging fishers' memories, we analyzed over 20 years of data on Ulva lactuca blooms and their effects on fishing activities and fish resources in a tropical semi-arid region of Brazil. We estimated the timing, seasonality, and impacts of these bloom episodes on fish catches, fishing gears, and fishery revenues. Since 2010, blooms have become more frequent, particularly during dry seasons in shallow estuaries, likely exacerbated by nutrient enrichment, extended water residence time, and inadequate wastewater treatment. Net-based gear is particularly affected, with fish catches decreasing by up to sevenfold during bloom seasons, leading to income losses of approximately 50 %. Addressing eutrophication through active public policies on effluent treatment is crucial to mitigating economic impacts on vulnerable communities and managing future blooms, which are expected to worsen with climate change.

Microclimatic effects of tree shelters on the early establishment and resilience of seeded acorns vs. outplanted seedlings.

Little is known about the effects of tree shelters on the early response of oak seedlings produced by acorn seeding. In this paper, we explore the effects on holm oak (Quercus ilex L. subsp. ballota (Desf.) Samp.) seedlings of the microenvironment created by the tree shelters and the restoration method (seeding vs. outplanting) in terms of emergence, survival, growth, and resilience after harvesting. For this purpose, seedling height [H], root collar diameter [RCD], number of leaves, and aerial biomass were monitored. We made two sowings of acorns in February 2017 and February 2018, together with a seedling outplanting in February 2018 in a common garden site in semiarid SE Spain. In total, 600 acorns were randomly sowed and 300 nursery-grown seedlings were outplanted and studied until 2022. Mother tree and initial acorn mass were also monitored as additional variables in the analyses. Tree shelters consisted of closed plastic Tubes, Mixed tubes, Cork shelters, Tiles, and a Control with no shelter. Emergence rate was positively influenced by the Tube shelter (86%) as compared to the Control (64%), and especially by the initial acorn mass. By contrast, mother tree or year of sowing seemed to have no effect. The survival rate for the emerged acorns (88%) was statistically similar to that of outplanted seedlings (91%), and was unaffected by mother tree, tree shelter, or acorn mass. In terms of growth, the slenderness ratio (H:RCD) was considerably higher in seedlings from directly seeded acorns than for those that were outplanted. With the exception of Tile, all the shelters showed a higher slenderness ratio than the Control, especially the Tube shelter, which also showed a lower number of leaves and a lower aboveground dry biomass than the Control, Cork, and Tile shelters. Virtually no interactions were observed between the mother tree and the tree shelter. At harvesting, all the growth-related parameters were still strongly dependent on the acorn mass and the initial seedling features recorded after the first growing season. Resprouting rate and growth were also highly dependent on the acorn mass and the plant features at the beginning of the experiment and at harvesting. In summary, we did not find evidence to support tree shelters to improve the microclimate of holm oak seedlings both seeded or outplanted. Direct acorn seeding can be as successful as outplanting of nursery-grown seedlings. Selection of heavy acorns from mothers with a high germination and emergence rate is highly advisable.

Substituting partial chemical nitrogen fertilizers with organic fertilizers maintains grain yield and increases nitrogen use efficiency in maize.

Introduction: Long-term application of excessive nitrogen (N) not only leads to low N use efficiency (NUE) but also exacerbates the risk of environmental pollution due to N losses. Substituting partial chemical N with organic fertilizer (SP) is an environmentally friendly and sustainable fertilization practice. However, the appropriate rate of SP in rainfed maize cropping systems in semi-arid regions of China is unknown. Methods: Therefore, we conducted a field experiment between 2021 and 2022 in a semi-arid region of Northern China to investigate the effects of SP on maize growth, carbon and N metabolism (C/NM), and NUE. The following treatments were used in the experiment: no N application (CK), 100% chemical N (SP0, 210 kg N ha-1), and SP substituting 15% (SP1), 30% (SP2), 45% (SP3), and 60% (SP4) of the chemical N. The relationship between these indicators and grain yield (GY) was explored using the Mantel test and structural equation modeling (SEM). Results and discussion: The results found that the SP1 and SP2 treatments improved the assimilates production capacity of the canopy by increasing the leaf area index, total chlorophyll content, and net photosynthetic rate, improving dry matter accumulation (DMA) by 6.2%-10.6%, compared to the SP0 treatment. SP1 and SP2 treatments increased total soluble sugars, starch, free amino acids, and soluble protein contents in ear leaves via increasing the enzymatic reactions related to C/NM in ear leaves during the reproductive growth stage compared with SP0 treatment. The highest plant nitrogen uptake (PNU) and nitrogen recovery efficiency were obtained under the SP2 treatment, and the GY and nitrogen agronomic efficiency were higher than the SP0 treatment by 9.2% and 27.8%. However, SP3 and SP4 treatments reduced DMA and GY by inhibiting C/NM in ear leaves compared to SP0 treatment. Mantel test and SEM results revealed that SP treatments indirectly increased GY and PNU by directly positively regulating C/NM in maize ear leaves. Therefore, in the semi-arid regions, substituting 30% of the chemical N with SP could be considered. This fertilizer regime may avoid GY reduction and improve NUE. This study provides new insights into sustainable cultivation pathways for maize in semi-arid regions.

Direct and Legacy Effects of Varying Cool-Season Precipitation Totals on Ecosystem Carbon Flux in a Semi-Arid Mixed Grassland.

In the semi-arid grasslands of the southwest United States, annual precipitation is divided between warm-season (July-September) convective precipitation and cool-season (December-March) frontal storms. While evidence suggests shifts in precipitation seasonal distribution, there is a poor understanding of the ecosystem carbon flux responses to cool-season precipitation and the potential legacy effects on subsequent warm-season carbon fluxes. Results from a two-year experiment with three cool-season precipitation treatments (dry, received 5th percentile cool-season total precipitation; normal, 50th; wet, 95th) and constant warm-season precipitation illustrate the direct and legacy effects on carbon fluxes, but in opposing ways. In wet cool-season plots, gross primary productivity (GPP) and ecosystem respiration (ER) were 103% and 127% higher than in normal cool-season plots. In dry cool-season plots, GPP and ER were 47% and 85% lower compared to normal cool-season plots. Unexpectedly, we found a positive legacy effect of the dry cool-season treatment on warm-season carbon flux, resulting in a significant increase in both GPP and ER in the subsequent warm season, compared to normal cool-season plots. Our results reveal positive legacy effects of cool-season drought on warm-season carbon fluxes and highlight the importance of the relatively under-studied cool-growing season and its direct/indirect impact on the ecosystem carbon budget.

Data from multi-scaled measurements for soil, hydraulic, vegetative, and meteorological variables in the Xilin River Basin, Inner Mongolia.

The grazed grasslands of Inner Mongolia offer a critical research setting for studying the impacts of long-term grazing on soil, hydraulic, vegetative, and meteorological variables, and potentially contribute to examine threshold responses to grazing activity or climate dynamics in colder Eurasian temperate grasslands. The dataset consists of long-term observations of soil temperature and moisture, as well as other related parameters across three scales: pedon, field, and catchment scale. This includes: i) At the pedon scale, data collection was conducted on five sites: long-term grazing exclusion since 1979 (UG79), short-term grazing exclusion since 1999 (UG99), continuous grazing (CG), heavy year-round grazing (HG), and moderate winter grazing (WG), from May 2004 to August 2008. Profiled soil moisture at depths of 5, 20, and 40 cm was continuously monitored using theta-probes, while soil temperature at depths of 2, 8, 20, 40, and 100 cm was monitored using Platinum ground temperature probes. Since 2016, newly automated monitoring instruments were also used for continuous monitoring of soil temperature and moisture at depths of 10, 30, 50, 70, and 100 cm at the UG79, UG99, and CG sites. ii) At the field scale, during the growth period from 2004 to 2008, a regular sampling grid (about 100 points) was established in all five sites using differential GPS and UTM systems. Soil water content, water drop penetration time, shear strength, and hydraulic conductivity were measured once per week/month. At the beginning, soil organic carbon concentration, bulk density, soil texture, and plant parameters were also taken at each grid point. iii) At the catchment scale, a field sampling scheme was designed, using land use and soil type as stratification variables. A total of 30 sampling points were selected. At each sampling point, detailed soil surveys were conducted to measure soil profile characteristics, including soil colour, texture, structure, and chemical elements. Additionally, some soil hydrological properties were recorded on site. This dataset offers critical insights into the factors influencing livestock carrying capacity in Mongolian grasslands. The integration of these data types can substantially enhance our understanding and management of these ecosystems.

Evaluating the spatiotemporal patterns of drought characteristics in a semi-arid region of Limpopo Province, South Africa.

Drought is a complex phenomenon resulting from below-average rainfall and is characterized by frequency, duration, and severity, occurring at a regional scale with dire consequences, especially in semiarid environments. This study used the Reconnaissance Drought Index (RDI) to assess drought severity in two district municipalities in Limpopo Province. Rainfall and air temperature data from 12 stations covering 1970-2020 were obtained from the Agricultural Research Council. The calculation of RDI relies on the monthly accumulation ratio of total rainfall to potential evapotranspiration (PET). For this study, PET was estimated using the Hargreaves and Samani temperature-based approach. The RDI results showed a high spatial-temporal variation in drought characteristics over the study area. All stations experienced extreme drought conditions in different years, with the maximum drought severity (-3.40) occurring from 2002-2003 in the western parts of the study area, indicating extreme drought. Furthermore, the results revealed continuous drought conditions over various periods, including severe droughts between 1995 and 1998 and between 2014 and 2016, with the severity varying between mild and moderate drought conditions. The results reveal notable but nonuniform drought patterns as the climate evolves, with potential implications for water availability and livelihoods. The study's findings underscore the significance of adopting multidimensional approaches to drought assessment that encompass meteorological and hydrological factors to inform strategies for adaptive water management and policy formulation in the face of a changing climate.

Seed production capacity and viability of pasture legumes under the influence of phosphorus management.

Seed production of a forage legume in the natural pastures reflects its ability to reseed and enrich the pasture. This study aimed at improving the productivity and nutritional value of pastures through enhancement the ability of leguminous species to restore pastures under phosphorus management. A field study was conducted at the research station of Farako-Bâ, Burkina Faso. Treatments included two legumes (Aeschynomene histrix and Stylosanthes hamata) and two levels of phosphorus application (Po = 0 and P1 = 100 kg P ha1). The experimental design was a split-plot arrangement with legumes as the main treatment and Phospohorus application as the sub-treatment. Results showed that the phosphorus application had a significant effect on the seed production of the two legumes, whereby A. histrix seed production of was significantly higher than that of S. hamata with or without phosphorus application (P < 0.05). Seed production was 566.92 kg/ha and 299.08 kg/ha for A. histrix, S. hamata, respectively. The fertility of A. histrix seeds (92.49 %) is very significantly higher than those of S. hamata (62.07 %) (P < 0.01). Phosphorus only improved seed weight of S. hamata (P < 0.05), unlike A. histrix, where this improvement was not statistically significant. In view of these results, A. histrix and S. hamata can be strongly recommended for the enrichment of Sudanian natural pastures.

Effect of replacing ground corn with cactus pear Nopalea cochenillifera (L.) on feed intake and digestibility, water intake, milk production and composition in Holstein × Gyr cows.

The objective of this study was to evaluate the intake and digestibility of nutrients, production and composition of milk, and water intake of lactating dairy cows fed standard diets in which ground corn (C) was replaced by up to 100% in the diet by cactus pear (CP). Eight Girolando cows (½ Gyr x ½ Holstein), 3rd calf multiparous, with 60 to 80 days of lactation and an average weight of 450.0 ± 30.0 kg, were randomly distributed in a double Latin square (4 × 4). Four experimental diets were evaluated: (100% C + 0% CP), (66.6% C + 33.3% CP), (33.3% C + 66.6% CP), and (0% C + 100% CP). There was a difference (P < 0.05) in the intake of CP and EE (kg.day- 1), with a quadratic effect and a linear reduction, respectively, with substitution. The maximum CP intake of 3.05 kg.day- 1 was found at 46.07% and EE intake fell by 3.81 g for each percentage unit of cactus pear added to the diet. There was a quadratic difference (P < 0.05) for DM intake in %BW and g.kg BW0,75, with maximum values of 3.97%BW and 186.8 g.kg BW0,75 with the substitution of 54.83 and 53.17%, respectively. There was a quadratic effect (P < 0.05) for the intake of NDF in %BW, with the maximum intake of 1.3% at the 74.69% substitution level. There was a linear reduction (P < 0.05) in the digestibility of DM, NDF, and TDN, and for the other nutrients there was no substitution effect (P > 0.05). There was no difference (P > 0.05) in milk production and composition. There was a linear reduction (P < 0.05) in water intake. Cactus pear can be used in a promising way to replace ground corn up to 100% in the diet of lactating dairy cows.

Eddy covariance measurements reveal a decreased carbon sequestration strength 2010-2022 in an African semiarid savanna.

Monitoring the changes of ecosystem functioning is pivotal for understanding the global carbon cycle. Despite its size and contribution to the global carbon cycle, Africa is largely understudied in regard to ongoing changes of its ecosystem functioning and their responses to climate change. One of the reasons is the lack of long-term in situ data. Here, we use eddy covariance to quantify the net ecosystem exchange (NEE) and its components-gross primary production (GPP) and ecosystem respiration (Reco) for years 2010-2022 for a Sahelian semiarid savanna to study trends in the fluxes. Significant negative trends were found for NEE (12.7 ± 2.8 g C m2 year-1), GPP (39.6 ± 7.9 g C m2 year-1), and Reco (32.2 ± 8.9 g C m2 year-1). We found that NEE decreased by 60% over the study period, and this decrease was mainly caused by stronger negative trends in rainy season GPP than in Reco. Additionally, we observed strong increasing trends in vapor pressure deficit, but no trends in rainfall or soil water content. Thus, a proposed explanation for the decrease in carbon sink strength is increasing atmospheric dryness. The warming climate in the Sahel, coupled with increasing evaporative demand, may thus lead to decreased GPP levels across this biome, and lowering its CO2 sequestration.

Outdoor thermal sensation scale through biometeorological assessment for semi-arid climate.

Extreme temperatures in urban areas cause discomfort leading to a rise in health risks, like heat-related mortality (hyperthermia). It is, hence, important to have a comfortable thermal environment. Assessing outdoor thermal comfort is challenging and complicated due to its dependencies on biometeorological and psychological factors. This study investigates the outdoor thermal comfort in Ahmedabad, a city with semi-arid climate in India through biometeorological measurements and thermal comfort surveys. The study carried out thermal comfort surveys of 1620 subjects spread across the city in 2022-23 covering all the seasons. The temperature and relative humidity were in the range of 21.6 °C to 44.9 °C and 8 to 86% respectively. About 43% of the subjects felt thermally comfortable during the survey. Based on the survey results, the annual neutral Physiological Equivalent Temperature (PET) obtained was 27.5 °C, and the comfortable PET range was between 21.1 °C and 33.9 °C which covers a wide range. Neutral PET for summer and winter seasons obtained were similar, which indicates winters are getting milder and people of Ahmedabad are getting more adaptive towards warmer temperature. These results hold special significance as there is limited research on outdoor thermal comfort in such climate zone of India.

Water periods impact the structure and metabolic potential of the nitrogen-cycling microbial communities in rivers of arid and semi-arid regions.

This study examined the influence of water periods on river nitrogen cycling by analysing nitrogen functional genes and bacterial communities in the Qingshui River, an upstream tributary of the Yellow River in China. Nitrate nitrogen predominated as inorganic nitrogen during the low-flow seasons, whereas salinity was highest during the high-flow seasons. Overall, the functional gene abundance increased with decreasing water volume, and nitrogen concentrations were determined by various specific gene groups. The relative abundance of bacteria carrying these genes varied significantly across water periods. The abundance of Pseudomona, Hydrogenophaga (carrying narGHI and nirB genes), and Flavobacterium (carrying nirK, norBC, and nosZ genes) significantly increased during the low-flow seasons. Nitrogen transformation bacteria exhibited both symbiotic and mutualistic relationships. Microbial network nodes and sizes decreased with decreasing water volume, whereas modularity increased. Additionally, the water period affected the functional microbial community structure by influencing specific environmental factors. Among them, SO42- primarily determined the denitrification, dissimilatory nitrate reduction to ammonium, and assimilatory nitrate reduction to ammonium communities, whereas NO2--N and Mg2+ were the main driving factors for the nitrogen-fixing and nitrifying communities, respectively. These findings have substantial implications for better understanding the reduction in river nitrogen loads in arid and semi-arid regions during different water periods.

Climate change, culture and health: Indigenous resilience, a study from Turkana County, Kenya.

Climate change and recurring droughts-induced effects on health are becoming an increasingly main global, cultural and public health burden. The heaviest health burden leans on the fragile socio-economic systems among the remote agro-pastoral communities, living in the arid and semi-arid lands (ASALs). Previous studies underlined the indispensability of indigenous knowledge (IK) for resilience-driven disaster risk reduction (DRR) strategies. However, more attention has been drawn towards the necessity of IK in weather forecasts, with less emphasis on its indispensability to alleviate health burden associated with climate change and droughts. We explored the contextual application of IK-based adaptation and related complementarity aspects for culturally relevant and sustainable DRR strategies for the nomadic agro-pastoral communities in Lopur, Turkana, Kenya. Relying on a descriptive qualitative study in phenomenological approach, purposive sampling and focus group discussions with key community influencers, a thematic analysis was conducted for an in-depth understanding and interpretation of data patterns. The contextualised insights revealed the growing vulnerability as a result of the disconnect between modern interventions, IK and the newly adopted environmental degrading coping tactics. Policy-wise, the findings portrayed the necessity for cultural integration and incorporation of indigenous knowledge-based strategies and systems for reinforced information dissemination, accessibility and acceptability for droughts preparedness and response. Contribution: This study underlined the existing room for scientific exploration of the already existing indigenous knowledge-based solutions for food and water insecurity, towards improved resilience for the vulnerable communities experiencing inequitable climate change calamities in the ASALs.

Deterministic processes influence bacterial more than fungal community assembly during the development of biological soil crusts in the desert ecosystem.

Biological soil crusts (biocrusts) constitute a crucial biological component of the soil surface in arid and semi-arid ecosystems. Understanding the variations in soil microbial community assembly across biocrust successional stages is essential for a deeper comprehension of microbial biodiversity and desert ecosystem functioning. However, knowledge about the mechanisms of microbial community assembly and the factors influencing its development remains limited. In this study, we utilized amplicons sequencing to assess the compositions of bacterial and fungal communities in bare sand and three types of biocrusts (light cyanobacterial biocrusts, dark cyanobacterial biocrusts, and moss crusts). Subsequently, we analyzed the ecological processes shaping microbial community composition and structure, along with the influencing factors. Our results revealed a significant increase in bacterial diversity and no significant changes in fungal diversity during biocrust development. The relative abundances of the copiotrophic bacteria (e.g., Actinobacteria, Acidobacteria, and Bacteroidetes) showed significant increases, while oligotrophic bacteria (e.g., Proteobacteria and Firmicutes) decreased over time. Moreover, the relative abundances of Ascomycota, which exhibit strong resistance to adverse environmental conditions, significantly decreased, whereas Basidiomycota, known for their ability to degrade lignin, significantly increased throughout biocrust development. Additionally, stochastic processes (dispersal limitation and drift) predominantly drove the assemblies of both bacterial and fungal communities. However, the relative importance of deterministic processes (homogeneous selection) in bacterial assembly increased during biocrust development. Structural equation modeling indicated that bacterial community assembly was primarily related to soil water content, whereas fungal community assembly was primarily related to total organic carbon. These findings provide a scientific foundation for investigating the formation and development of biocrusts, and further insights into the conservation and sustainable management of biocrust resources under future climate change scenarios.

Intensified river salinization alters nitrogen-cycling microbial communities in arid and semi-arid regions of China.

Freshwater salinization is receiving increasing global attention due to its profound influence on nitrogen cycling in aquatic ecosystems and the accessibility of water resources. However, a comprehensive understanding of the changes in river salinization and the impacts of salinity on nitrogen cycling in arid and semi-arid regions of China is currently lacking. A meta-analysis was first conducted based on previous investigations and found an intensification in river salinization that altered hydrochemical characteristics. To further analyze the impact of salinity on nitrogen metabolism processes, we evaluated rivers with long-term salinity gradients based on in situ observations. The genes and enzymes that were inhibited generally by salinity, especially those involved in nitrogen fixation and nitrification, showed low abundances in three salinity levels. The abundance of genes and enzymes with denitrification and dissimilatory nitrate reduction to ammonium functions still maintained a high proportion, especially for denitrification genes/enzymes that were enriched under medium salinity. Denitrifying bacteria exhibited various relationships with salinity, while dissimilatory nitrate reduction to ammonium bacterium (such as Hydrogenophaga and Curvibacter carrying nirB) were more inhibited by salinity, indicating that diverse denitrifying bacteria could be used to regulate nitrogen concentration. Most genera exhibited symbiotic and mutual relationships, and the highest proportion of significant positive correlations of abundant genera was found under medium salinity. This study emphasizes the role of river salinity on environment characteristics and nitrogen transformation rules, and our results are useful for improving the availability of river water resources in arid and semi-arid regions.

Analysis of canopy interception characteristics and influencing factors in typical artificial forest in the Loess Plateau semi-arid region.

Interception loss (IL) is an important process in the hydrological cycle within semi-arid forest ecosystems, directly affecting the amount of effective rainfall. However, the factors influencing IL during individual rainfall events remain to be quantified. This study collected rainfall, vegetation, and interception data during the 2022 and 2023 growing seasons in a typical black locust forest within the Zhifanggou watershed. It employed the Random Forest Regression (RFR) and back-propagation neural network (BPNN) methods to quantitatively evaluate the contribution rates of various factors to the IL and interception loss percentage (ILP). The IL among the 48 effective rainfall events was 172.05 mm, accounting for 19.54% of the rainfall amount. IL and ILP increased as the distance from the trunk decreased. During all rainfall events, both IL and ILP were significantly negatively correlated with the leaf area index (LAI) and canopy cover (CC); IL is significantly positively correlated with total rainfall (TR) and rainfall intensity (RI), while ILP is significantly negatively correlated with TR, RI, and rainfall duration (RD). The BPNN and RFR results indicated that rainfall, canopy, and tree characteristics contributed 43.06%, 44.79%, and 12.15% to IL, respectively, and 57.27%, 34.09%, and 8.63% to ILP, respectively. TR, CC, and LAI represented the primary influencing factors. Rainfall and canopy characteristics were the main factors affecting IL (ILP). As rainfall event magnitude increases, canopy contributions to IL and ILP decrease. In semi-arid areas, managing forest canopies to control IL helps address water imbalances in ecosystems.

Functional Activity of the Antioxidant System of Artemisia Genus Plants in the Republic of Buryatia (Russia) and Its Significance in Plant Adaptation.

Plants are sessile organisms and any changes in environmental factors activate various responses and defense mechanisms. Artemisia plants widely inhabit harsh conditions of arid and semiarid ecosystems. Using two species-a subshrub, Artemisia frigida, and an annual-biennial herb, Artemisia scoparia-the functioning of the antioxidant system of plants in semiarid territories have been examined. The activity of enzymatic antioxidants and the content of non-enzymatic antioxidants in both species as well as the antiradical activity of their extracts have been shown. Although the plants were collected in areas differing in moisture supply, the activity of enzymatic antioxidants and the content of non-enzymatic antioxidants corresponds to their physiological level, within the range of the norm of reaction, in wormwood. Consequently, conditions of differing moisture deficiency do not cause a specific biochemical response at the level of the antioxidant system in the studied species, which confirms their adaptability to these conditions. Meanwhile, A. frigida plants show greater morphological and biochemical plasticity than A. scoparia under changing growth conditions. Both species contain tissue monoterpenoids and sesquiterpenoids, the emission of which provides additional protection against high temperatures and drought. Their composition and contents of phenolic components illustrates the differences in adaptation between perennial and annual plants.