Variation In Water Availability Research Articles

Investigation of the seasonal microbiome of Anopheles coluzzii mosquitoes in Mali.

The poorly understood mechanisms of dry season persistence of Anopheles spp. mosquitoes through the dry season in Africa remain a critical gap in our knowledge of Plasmodium disease transmission. While it is thought that adult mosquitoes remain in a dormant state throughout this seven-month dry season, the nature of this state remains unknown and has largely not been recapitulated in laboratory settings. To elucidate possible connections of this state with microbial composition, the whole body microbiomes of adult mosquitoes in the dry and wet seasons in two locations of Mali with varying water availability were compared by sequencing the 16S ribosomal RNA gene. These locations were a village near the Niger River with year-round water sources (N’Gabakoro, “riparian”), and a typical Sahelian area with highly seasonal breeding sites (Thierola Area, “Sahelian”). The 16S bacterial data consisted of 2057 sequence variants in 426 genera across 184 families. From these data, we found several compositional differences that were seasonally and spatially linked. Counter to our initial hypothesis, there were more pronounced seasonal differences in the bacterial microbiome of riparian, rather than Sahelian areas. These seasonal shifts were primarily in Ralstonia, Sphingorhabdus, and Duganella spp. bacteria that are usually soil and water-associated, indicating these changes may be from bacteria acquired in the larval environment, rather than adulthood. In Sahelian dry season mosquitoes, there was a unique intracellular bacteria, Anaplasma, which likely was acquired through non-human blood feeding. Cytochrome B analysis of blood meals showed greater heterogeneity in host choice of An. coluzzii independent of season in the Thierola area compared to N’Gabakoro (77.5% vs. 94.6% human-origin blood meal, respectively), indicating a relaxation of anthropophily. Overall, this exploratory study provides valuable indications of spatial and seasonal differences in bacterial composition which help refine this difficult to study state.

Growth responses of Lantana (Lantana camara L.) varieties to varying water availability and light conditions

The Journal of the National Science Foundation of Sri Lanka publishes the results of research in all aspects of Science and Technology. The journal also has a website at http://www.nsf.gov.lk/. 2021 Impact Factor: 0.682The JNSF provides immediate open access to its content on the principle that making research freely available to the public supports a greater global exchange of knowledge.Cover :Leatherback (a), green (b - adult & f - hatchling), hawksbill (c) and olive ridley (d) turtles who nest in Sri Lankan beaches, green turtle crawl marks (e) and by-catch of sea turtles in fisheries (c & d)Photo credits: SJ Perera (a & c), WPN Perera (b & e), K Ekaratne (d & f)

Hydraulic traits and tree-ring width in Larix sibirica Ledeb. as affected by summer drought and forest fragmentation in the Mongolian forest steppe

Wood-anatomical traits determining the hydraulic architecture of Larix sibirica in the drought-limited Mongolian forest steppe at the southern fringe of the boreal forest respond to summer drought, but only weakly to variations in microclimate that depend on forest stand size. Siberian larch (L. sibirica Ledeb.) is limited by summer drought and shows increasing mortality rates in the Mongolian forest steppe. The climate sensitivity of stemwood formation increases with decreasing forest stand size. The trees’ hydraulic architecture is crucial for drought resistance and thus the capability to deal with climate warming. We studied whether hydraulic traits were influenced by temporal or forest size-dependent variations in water availability and were related to tree-ring width. Hydraulic traits (tracheid diameter, tracheid density, potential sapwood area-specific hydraulic conductivity) of earlywood were studied in stemwood series of 30 years (1985–2014) and were related to climate data. Tree-ring width was measured for the same period. Trees were selected in stands of four different size classes with increasing drought exposure with decreasing stand size. Tracheid diameters and hydraulic conductivity decreased with decreasing late summer precipitation of the previous year and were positively correlated with tree-ring width. Forest stand size had only weak effects on hydraulic traits, despite known effects on stemwood increment. Decreasing tracheid diameters and thus hydraulic conductivity are a drought acclimation of L. sibirica in the Mongolian forest steppe. These acclimations occur as a response to drought periods but are little site-dependent with respect to stand size.

Rhizobacteria improve sugarcane growth and photosynthesis under well‐watered conditions

AbstractMorpho‐physiological changes caused by particular plant growth‐promoting rhizobacteria were evaluated in sugarcane plants under varying water availability. Under well‐watered conditions, we have found one rhizobacteria isolate (IAC‐RBcr5) able to enhance root dry matter and photosynthesis of sugarcane plants. The IAC‐RBcr5 genome was sequenced and high similarity was found with Pseudomonas putida GB‐1. Based on increased root system size of inoculated plants, we hypothesised that sugarcane plants inoculated with IAC‐RBcr5 would have improved performance under water deficit. Although IAC‐RBcr5 had improved plant leaf CO2 assimilation under water shortage, inoculation caused reduction of biomass accumulation in sugarcane. The negative influence of water deficit on shoot growth rate and root traits such as volume, area, diameter, length and specific root area was higher in plants treated with IAC‐RBcr5 as compared to non‐inoculated ones. However, rhizobacteria‐induced improvements in leaf and root proline contents would represent a strategy for storing carbon and nitrogen during low water availability and helping both organisms to resume their metabolism after rehydration. In conclusion, we found and identified a rhizobacterium able to improve growth and photosynthesis of sugarcane plants. Such benefit for plant growth was lost under low water availability as a likely consequence of increased carbon‐energy demand by rhizobacteria and their sensitivity to drought.

Modelling the water energy nexus: should variability in water supply impact on decision making for future energy supply options?

Abstract. Many countries, like South Africa, Australia, India, China and the United States, are highly dependent on coal fired power stations for energy generation. These power stations require significant amounts of water, particularly when fitted with technology to reduce pollution and climate change impacts. As water resources come under stress it is important that spatial variability in water availability is taken into consideration for future energy planning particularly with regards to motivating for a switch from coal fired power stations to renewable technologies. This is particularly true in developing countries where there is a need for increased power production and associated increasing water demands for energy. Typically future energy supply options are modelled using a least cost optimization model such as TIMES that considers water supply as an input cost, but is generally constant for all technologies. Different energy technologies are located in different regions of the country with different levels of water availability and associated infrastructure development and supply costs. In this study we develop marginal cost curves for future water supply options in different regions of a country where different energy technologies are planned for development. These water supply cost curves are then used in an expanded version of the South Africa TIMES model called SATIM-W that explicitly models the water-energy nexus by taking into account the regional nature of water supply availability associated with different energy supply technologies. The results show a significant difference in the optimal future energy mix and in particular an increase in renewables and a demand for dry-cooling technologies that would not have been the case if the regional variability of water availability had not been taken into account. Choices in energy policy, such as the introduction of a carbon tax, will also significantly impact on future water resources, placing additional water demands in some regions and making water available for other users in other regions with a declining future energy demand. This study presents a methodology for modelling the water-energy nexus that could be used to inform the sustainable development planning process in the water and energy sectors for both developed and developing countries.

Opportunities for Joint Water–Energy Management: Sensitivity of the 2010 Western U.S. Electricity Grid Operations to Climate Oscillations

Abstract The increasing interconnectedness of energy and water systems makes it important to understand how interannual variations in water availability—and climate oscillations—could potentially impact the electric grid operations. The authors assess the vulnerability of the current western U.S. grid to historical climate variability using multiple energy and water system models. A 55-yr-long natural water availability benchmark is combined with the 2010 level of water demand from an integrated assessment model to drive a large-scale water management model over the western United States. The regulated flow at hydropower and thermoelectric power plants is then translated into boundary conditions for electricity generation in a production cost model. This analysis focuses on assessing regional interdependencies and the impact of interannual changes in water availability on power system operations, including reliability, cost, and carbon emissions. Results for August grid operations—when stress on the grid is often highest—show a range of sensitivity in production cost (–8% to +11%) and carbon emissions (–7% to +11%), as well as a 1-in-10 chance that electricity demand will exceed estimated supply. The authors also show that operating costs are lower under neutral El Niño–Southern Oscillation (ENSO) conditions than under other ENSO phases; carbon emissions are highest under La Niña conditions, especially in California; and the risk of brownouts may be higher under neutral and negative ENSO conditions. These results help characterize the grid’s performance under historical climate variations, are useful for seasonal and multiyear planning of joint water–electricity management, and can be used to support impact, adaptation, and vulnerability analyses.

Effect of Epichloë gansuensis endophyte and transgenerational effects on the water use efficiency, nutrient and biomass accumulation of Achnatherum inebrians under soil water deficit

This study explored the effects of Epichloe gansuensis endophyte on water use efficiency (WUE), nutrient content and biomass accumulation of Achnatherum inebrians (drunken horse grass, DHG) under varying water availability. It also examined possible transgenerational effects (TGE) on above indicators. DHG with (EI) and without endophyte (EF), from seed of plants of the same seed-line that had been grown in Yuzhong (YZ-D, relatively dry) and Xiahe (XH-W, relatively wet), were grown under limited water conditions (LWC). Plant height, leaf number and chlorophyll content were monitored dynamically. After 10 weeks, the biomass, photosynthetic indexes and C, N, P content of plants was determined. The endophyte increased plant height and chlorophyll content, but decreased plant leaf number, and the CO2 concentration, while increasing other photosynthetic indexes. The biomass, N and P content were higher in EI than EF plants of the YZ-D DHG, but not the C content and root weight. However, there were almost no significant affects on these factors between EI and EF plants of the XH-W DHG. The endophyte enhanced WUE and maintained the growth of plants under LWC by improving photosynthetic efficiency and promoting nutrient absorption. However, TGE also affected this process.

Ecosystem Tipping Points Due to Variable Water Availability and Cascading Effects on Food Security in Sub‐Saharan Africa

The frequency, duration, and magnitude of extreme weather events such as droughts, floods, and variation in rainfall onset and cessation periods will continue to increase. Such stress may result in significant shifts in the functioning of ecosystems. As climate change affects the capacity of ecosystems to mitigate the effects of extreme events such as drought and floods, leading to disruptions in water supply and food production, or to the destruction of infrastructure, human well‐being is ultimately impacted. Chief among those impacts are those on the four dimensions of food security: food availability, accessibility, utilization, and stability. An interesting channel of impacts is through the observed and forecasted increase in the variability of water availability. This is said to cause uncertainty in agricultural production resulting in reduced productivity, food insecurity, weak economic growth and the widespread food poverty in Africa today. Due to overreliance on rain‐fed agriculture in Sub‐Saharan Africa, people usually engage in both temporary and permanent migration after consecutive years of bad harvests and reduced incomes from agriculture with migration acting as an adaptation strategy to climatic shocks. Food value chains can be significantly affected, something that the paper identifies as an area that requires further research mainly on the resilience of food value chains to water variability.

Geographical variation in the standard physiology of brushtail possums (Trichosurus): implications for conservation translocations.

Identifying spatial patterns in the variation of physiological traits that occur within and between species is a fundamental goal of comparative physiology. There has been a focus on identifying and explaining this variation at broad taxonomic scales, but more recently attention has shifted to examining patterns of intra-specific physiological variation. Here we examine geographic variation in the physiology of brushtail possums (Trichosurus), widely distributed Australian marsupials, and discuss how pertinent intra-specific variation may be to conservation physiology. We found significant geographical patterns in metabolism, body temperature, evaporative water loss and relative water economy. These patterns suggest that possums from warmer, drier habitats have more frugal energy and water use and increased capacity for heat loss at high ambient temperatures. Our results are consistent with environmental correlates for broad-scale macro-physiological studies, and most intra-generic and intra-specific studies of marsupials and other mammals. Most translocations of brushtail possums occur into Australia's arid zone, where the distribution and abundance of possums and other native mammals have declined since European settlement, leading to reintroduction programmes aiming to re-establish functional mammal communities. We suggest that the sub-species T. vulpecula hypoleucus from Western Australia would be the most physiologically appropriate for translocation to these arid habitats, having physiological traits most favourable for the extreme Ta, low and variable water availability and low productivity that characterize arid environments. Our findings demonstrate that geographically widespread populations can differ physiologically, and as a consequence some populations are more suitable for translocation to particular habitats than others. Consideration of these differences will likely improve the success and welfare outcomes of translocation, reintroduction and management programmes.

Spatio-Temporal Variation of Water Availability in a River Basin under CORDEX Simulated Future Projections

In the present study, spatio-temporal variability of hydrological components under climate change is analysed over Wainganga River basin, India. In order to address the climate change projection, hydrological modelling is carried out using a macro scale, semi-distributed three (3)-Layer Variable Infiltration Capacity (VIC-3 L) model. The high-resolution (0.5o × 0.5o) meteorological variables are divided into multiple periods to calibrate and validate the VIC-3 L model. The future projections (2020–2094) of the water balance components are achieved using the high resolution hydrological variables from the COordinated Regional Downscaling EXperiment (CORDEX) dataset under Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. The uncertainty associated with the multi-model projections are evaluated using Reliability Ensemble Averaging (REA) and the bias correction is accomplished with non-parametric quantile mapping. A probabilistic based areal drought index is also computed for different scenarios using Standardized Precipitation Evapotranspiration Index (SPEI). From the results, it is observed that amount of rainfall, evapotranspiration, and runoff has increased over the basin with no change in the spatial pattern. However, temporal variability is noticed with an increasing trend for rainfall and runoff in the non-monsoon season than the monsoon. Streamflow is expected to increase significantly, especially for medium to low flows (those occurring between 0.2 and 0.9 probability of exceedance in a Flow Duration Curve). In addition, the area under the drought condition has decreased under the projected climate scenarios.

Growth and ursolic acid content of pearl grass (Hedyotis corymbosa) on variations in water availability

Abstract. Anam K, Mudyantini, Rakhmawati R. 2017. Growth and ursolic acid content of pearl grass (Hedyotis corymbosa) on variations in water availability. Cell Biol Dev 1: 55-62. The purpose of this study is to determine how different water sources affect the growth and levels of ursolic acid in pearl grass (Hedyotis corymbosa (L.) Lam.). A factorial, completely randomized design (CRD) with a single factor of five replications each was used for the experiment. Water stress conditions were created by providing different levels of water availability in the growing media, namely 40, 60, 80, and 100% field capacity (control). The plants were given the treatment for 8 weeks. Plant growth, including the number of leaves, fresh and dry weight, and plant ursolic acid content, were all measured in this study. The data were analyzed using analysis of variance (ANOVA), and the DMRT test at the 5% test level was used to determine the significant difference between treatments. The results showed that the water availability treatment significantly affected the number of leaves, fresh weight, and dry weight, but it did not affect the ursolic acid content in plants. The treatment with the lowest water availability (40% KL) produced low yields on growth parameters and ursolic acid levels. Ursolic acid levels were lowest under drought stress conditions (40% KL), while they were highest under excess water conditions (100% KL).

Physiological Plasticity Is Important for Maintaining Sugarcane Growth under Water Deficit.

The water availability at early phenological stages is critical for crop establishment and sugarcane varieties show differential performance under drought. Herein, we evaluated the relative importance of morphological and physiological plasticity of young sugarcane plants grown under water deficit, testing the hypothesis that high phenotypic plasticity is associated with drought tolerance. IACSP95-5000 is a high yielding genotype and IACSP94-2094 has good performance under water limiting environments. Plants were grown in rhizotrons for 35 days under three water availabilities: high (soil water matric potential [Ψm] higher than -20 kPa); intermediate (Ψm reached -65 and -90 kPa at the end of experimental period) and low (Ψm reached values lower than -150 kPa). Our data revealed that morphological and physiological responses of sugarcane to drought are dependent on genotype and intensity of water deficit. In general, IACSP95-5000 showed higher physiological plasticity given by leaf gas exchange and photochemical traits, whereas IACSP94-2094 showed higher morphological plasticity determined by changes in leaf area (LA) and specific LA. As IACSP94-2094 accumulated less biomass than IACSP95-5000 under varying water availability, it is suggested that high morphological plasticity does not always represent an effective advantage to maintain plant growth under water deficit. In addition, our results revealed that sugarcane varieties face water deficit using distinct strategies based on physiological or morphological changes. When the effectiveness of those changes in maintaining plant growth under low water availability is taken into account, our results indicate that the physiological plasticity is more important than the morphological one in young sugarcane plants.

Forage Options for Dairy Farms with Reduced Water Availability in the Southern Murray Darling Basin of Australia

The dairy industry in the southern Murray Darling Basin region of Australia is a major consumer of irrigation water because rainfall is low relative to evapotranspiration and the industrys relies heavily on irrigated temperate pastures and fodder crops. Water reforms, and potential climate change scenarios for this region suggest that there will be an overall decline in rainfall and water available for irrigation in the future. For the irrigated dairy industry to remain economically viable, there is a need for dairy farmers to improve the water productivity (WP) of their forage systems and to be able to respond to year-to-year, and within year, variation in water availability. Researchers and dairy farmers are evaluating strategies to increase WP. These include: (i) selecting better-adapted species for current and predicted climatic conditions; (ii) using species that can survive and still be productive under reduced irrigation and then recover when full irrigation is restored; (iii) modifying irrigation strategies to reduce water use whilst maintaining WP; and (iv) grazing management strategies that facilitate the survival during, and recovery after, periods of moisture stress. This review will examine these strategies and discusses their potential to optimise forage production from irrigation water inputs so that the dairy industry in the southern Murray Darling Basin remains viable in the future.

Climate change impacts analysis on hydrological processes in the Weyib River basin in Ethiopia

The study aims to examine the variation of hydrological processes (in terms of mean annual, seasonal, and monthly) under changing climate within the Weyib River basin in Ethiopia at both basin and sub-basin level using ArcSWAT hydrologic model. The climate change impacts on temperature and precipitation characteristics within the basin have been studied using GFDL-ESM2M, CanESM2, and GFDL-ESM2G models for RCP8.5, RCP4.5, and RCP2.6 scenarios from coupled model inter-comparison project 5 (CMIP5) which have been downscaled by SDSM. The results revealed that the mean annual temperature and precipitation reveal a statistically significant (at 5% significant level) increasing trend in the nine ESM-RCP scenarios for all the future time slices. The mean annual actual evapotranspiration, baseflow, soil water content, percolation, and water availability in the stream exhibit a rise for all the ESMs-RCP scenarios in the entire basin and in all the sub-basins. However, surface runoff and potential evapotranspiration show a decreasing trend. The mean annual water availability increases between 9.18 and 27.97% (RCP8.5), 3.98 and 19.61% (RCP4.5), and 11.82 and 17.06% (RCP2.6) in the entire basin. The sub-basin level analysis reveals that the annual, seasonal, and monthly variations of hydrological processes in all the sub-basins are similar regarding direction but different in magnitude as compared to that of the entire basin analysis. In addition, it is observed that there is a larger monthly and seasonal variation in hydrological processes as compared to the variation in annual scale. The net water availability tends to decline in the dry season; this might cause water shortage in the lowland region and greater increases in an intermediate and rainy seasons; this might cause flooding to some flood prone region of the basin. Since the variation of water availability among the sub-basins in upcoming period is high, there is a scope of meeting agriculture water demand through water transfer from sub-basin having more available water in small area to the sub-basin having less available water in a larger agricultural area.

Spatial Variation in Seasonal Water Poverty Index for Laos: An Application of Geographically Weighted Principal Component Analysis

Water poverty, defined as insufficient water of adequate quality to cover basic needs, is an issue that may manifest itself in multiple ways. Extreme seasonal variation in water availability, such as in Laos, located in Monsoon Asia, results in large differences in water poverty conditions between dry and wet seasons. In this study, seasonal Water Poverty Indices (WPI) are developed for 8215 villages in Laos. WPI is a multidimensional composite index integrating five dimensions of water: resource availability, access to safe water, capacity to manage the resource, its use and environmental requirements. Principal Component Analysis (PCA) and Geographically Weighted PCA (GWPCA) were used to examine drivers of water poverty and to derive different weighting schemes. Three major drivers were identified: poverty, commercial/subsistence agriculture and village location. The least water poor areas are located around the capital city and along the Mekong River Valley while the highest water poverty is found in sparsely populated mountainous areas. Wet season WPI is on average more than 12 index points higher than in the dry season, but in some villages monsoon rain does not improve the situation. The results indicate large spatial and temporal differences in WPI within Laos. In analysis of WPI components, a mean–variance scaled PCA is recommended due to its capacity for uncovering processes driving water poverty. Extending to GWPCA is recommended when information on local differences is of interest.

Abiotic niche partitioning and negative density dependence drive tree seedling survival in a tropical forest.

In tropical tree communities, processes occurring during early life stages play a critical role in shaping forest composition and diversity through differences in species' performance. Predicting the future of tropical forests depends on a solid understanding of the drivers of seedling survival. At the same time, factors determining spatial and temporal patterns of seedling survival can play a large role in permitting species coexistence in diverse communities. Using long-term data on the survival of more than 45 000 seedlings of 238 species in a Neotropical forest, we assessed the relative importance of key abiotic and biotic neighbourhood variables thought to influence individual seedling survival and tested whether species vary significantly in their responses to these variables, consistent with niche differences. At the community level, seedling survival was significantly correlated with plant size, topographic habitat, neighbourhood densities of conspecific seedlings, conspecific and heterospecific trees and annual variation in water availability, in descending order of effect size. Additionally, we found significant variation among species in their sensitivity to light and water availability, as well as in their survival within different topographic habitats, indicating the potential for niche differentiation among species that could allow for species coexistence.

Assessing the effects of adaptation measures on optimal water resources allocation under varied water availability conditions

Human activities and climate change have altered the spatial and temporal distribution of water availability which is a principal prerequisite for allocation of different water resources. In order to quantify the impacts of climate change and human activities on water availability and optimal allocation of water resources, hydrological models and optimal water resource allocation models should be integrated. Given that increasing human water demand and varying water availability conditions necessitate adaptation measures, we propose a framework to assess the effects of these measures on optimal allocation of water resources. The proposed model and framework were applied to a case study of the middle and lower reaches of the Hanjiang River Basin in China. Two representative concentration pathway (RCP) scenarios (RCP2.6 and RCP4.5) were employed to project future climate, and the Variable Infiltration Capacity (VIC) hydrological model was used to simulate the variability of flows under historical (1956–2011) and future (2012–2099) conditions. The water availability determined by simulating flow with the VIC hydrological model was used to establish the optimal water resources allocation model. The allocation results were derived under an extremely dry year (with an annual average water flow frequency of 95%), a very dry year (with an annual average water flow frequency of 90%), a dry year (with an annual average water flow frequency of 75%), and a normal year (with an annual average water flow frequency of 50%) during historical and future periods. The results show that the total available water resources in the study area and the inflow of the Danjiangkou Reservoir will increase in the future. However, the uneven distribution of water availability will cause water shortage problems, especially in the boundary areas. The effects of adaptation measures, including water saving, and dynamic control of flood limiting water levels (FLWLs) for reservoir operation, were assessed and implemented to alleviate water shortages. The negative impacts from the South-to-North Water Transfer Project (Middle Route) in the mid-lower reaches of the Hanjiang River Basin can be avoided through the dynamic control of FLWLs in Danjiangkou Reservoir, under the historical and future RCP2.6 and RCP4.5 scenarios. However, the effects of adaptation measures are limited due to their own constraints, such as the characteristics of the reservoirs influencing the FLWLs. The utilization of storm water appears necessary to meet future water demand. Overall, the results indicate that the framework for assessing the effects of adaptation measures on water resources allocation might aid water resources management, not only in the study area but also in other places where water availability conditions vary due to climate change and human activities.

Floodplain ecosystem dynamics under extreme dry and wet phases in semi‐arid Australia

Abstract Ecological networks are a cornerstone of ecological theory, offering an integrated approach to understanding food webs and ecosystem dynamics required for restoration and conservation ecology. We investigated ecological network dynamics in a large floodplain undergoing extreme variation in water availability, with drought and subsequent flooding representing a resource pulse. We used structural equation models to quantify ecological network dynamics for the Lowbidgee floodplain (Australia), based on surveys over 5 years while the floodplain transitioned from extremely dry (2009, 2010) to wet (2011) and post‐wet (2013, 2014) conditions. We identified significant associations of species and trophic guilds with inundation at the site and floodplain scale, which allowed us to quantify the strength of biotic interactions within the network and the stability of interactions under differing patterns of resource availability. At the floodplain scale, most taxa responded strongly in distribution and abundance to the 2011 resource pulse, a widespread flood, but this response did not persist during subsequent years of moderate floods. In contrast, fish species, both native and exotic, responded strongly only in the post‐wet period. At the fine spatial scale (i.e., sites), complex responses were observed, with only waterbirds, frogs and tadpoles positively associated with inundation, while fish species showed a range of associations with fine‐scale inundation. Biotic interactions within sites, across all trophic guilds, were predominately overridden by inundation and water temperature, mediated by strong associations with aquatic vegetation. Stratifying the ecological network to dry, wet and post‐wet periods highlighted varying associations of taxa with fine‐scale inundation, generally responding synchronously to resource pulses, with relatively weak biotic interactions. Associations with site‐scale inundation were strongest during the post‐wet period for fishes and frogs. Only Litoria spp. (Hylidae) tadpoles, waterbirds and aquatic vegetation had positive associations with site‐scale inundation during the dry period. We conclude that responses of trophic guilds are largely dependent on the way they interact with their environment at particular spatial and temporal scales. Our investigation of this ecological network reinforced the importance of hydrological drivers over biotic interactions, with clear implications for the management of environmental flows, particularly in systems recovering from long‐term flow alteration. Management efforts should focus environmental flows to promote specialist species (e.g., southern bell frog, Litoria raniformis) and Murray hardyhead (Craterocephalus fluviatilis: Atherinidae), waterbirds and aquatic vegetation over the more generalist fish species that have established because of the loss of the natural flow regime.

Nitrogen deposition combined with elevated precipitation is conducive to maintaining the stability of the soil fungal diversity on the Stipa baicalensis steppe

Changes in nitrogen (N) deposition and precipitation can strongly influence grassland ecology. However, the combined effects of N and water addition on soil fungal genetic diversity, and especially the underlying influencing factors, are not well understood. We investigated the response of soil fungal α diversity to experimental N and water addition in a northern Chinese steppe. We found that N addition alone exceeding N100 (100 kg N·ha−1·yr−1) significantly increased soil fungal α diversity. However, when water was added, soil fungal diversity did not significantly change following N enrichment. Structural equation modelling (SEM) results indicated that N addition increased soil fungal α diversity, while N addition combined with irrigation maintains soil fungal diversity that would otherwise be enhanced by N addition. This results from reversing the correlation between soil fungal diversity and plants\\\\soil physicochemical properties. Our results provide evidence that the effects of N deposition regarding soil fungal diversity might be overestimated if we ignore variations in water availability.

Residual Fertilizer, Crop Sequence, and Water Availability Impact Rotational Nitrogen Balances

Inter‐seasonal N carryover increased subsequent crop N recovery. Increases in yield and N uptake after pea were partly attributed to higher N supply. The benefit of pea preceding winter wheat increased with increasing available water. Constructed rotation N balances incorporated inter‐seasonal changes in soil N supply. Rotational N use was modeled across a range of water‐limited environments. Accounting for multiple N sources provides an opportunity to improve rotational nitrogen use efficiency (rNUE) relative to single seasons. The project objectives were to assess the residual effects of fertilizer on subsequent crop yields and N recovery, attribute differences in winter wheat (Triticum aestivum L.) yield due to changes in N supply following pea (Pisum sativum L.), examine changes in N balances and grain yields across varying water availability, and develop and apply a multi‐year regression model that assesses changes in rotational N balances in water‐limited cropping systems. Fifty to 160 kg N ha−1 were unaccounted for following spring canola (Brassica napus L.) harvest, and excessive fertilization led to increases in post‐harvest residual N and crop residue N. Subsequent crops accumulated 10 to 15 kg more grain N ha−1, when following fertilized canola, while rotational apparent fertilizer N recovery ranged from 3 to 15%, primarily in the second year. The residual effect of fertilization was only attributed to residual soil N since net N mineralization was not statistically affected. Economic optimal yields of winter wheat were almost 900 kg ha−1 greater following pea than wheat due to elevated soil N supply and other rotational effects, increasing with water availability. A method of analyzing rotational N use is presented that integrates the effects of year‐to‐year changes in N supply across a range of yields, from which N balances may be constructed based on the emerging relationships among yield potential and soil and plant N processes.