Drought has been a major cause of agricultural disaster, yet how it affects the vulnerability of maize and wheat production in combination with several co-varying factors (i.e., phenological phases, ...agro-climatic regions, soil texture) remains unclear. Using a data synthesis approach, this study aims to better characterize the effects of those co-varying factors with drought and to provide critical information on minimizing yield loss. We collected data from peer-reviewed publications between 1980 and 2015 which examined maize and wheat yield responses to drought using field experiments. We performed unweighted analysis using the log response ratio to calculate the bootstrapped confidence limits of yield responses and calculated drought sensitivities with regards to those co-varying factors. Our results showed that yield reduction varied with species, with wheat having lower yield reduction (20.6%) compared to maize (39.3%) at approximately 40% water reduction. Maize was also more sensitive to drought than wheat, particularly during reproductive phase and equally sensitive in the dryland and non-dryland regions. While no yield difference was observed among regions or different soil texture, wheat cultivation in the dryland was more prone to yield loss than in the non-dryland region. Informed by these results, we discuss potential causes and possible approaches that may minimize drought impacts.
Satellite based remote sensing offers one of the few approaches able to monitor the spatial and temporal development of regional to continental scale droughts. A unique element of remote sensing ...platforms is their multi-sensor capability, which enhances the capacity for characterizing drought from a variety of perspectives. Such aspects include monitoring drought influences on vegetation and hydrological responses, as well as assessing sectoral impacts (e.g., agriculture). With advances in remote sensing systems along with an increasing range of platforms available for analysis, this contribution provides a timely and systematic review of multi-sensor remote sensing drought studies, with a particular focus on drought related datasets, drought related phenomena and mechanisms, and drought modeling. To explore this topic, we first present a comprehensive summary of large-scale remote sensing datasets that can be used for multi-sensor drought studies. We then review the role of multi-sensor remote sensing for exploring key drought related phenomena and mechanisms, including vegetation responses to drought, land-atmospheric feedbacks during drought, drought-induced tree mortality, drought-related ecosystem fires, post-drought recovery and legacy effects, flash drought, as well as drought trends under climate change. A summary of recent modeling advances towards developing integrated multi-sensor remote sensing drought indices is also provided. We conclude that leveraging multi-sensor remote sensing provides unique benefits for regional to global drought studies, particularly in: 1) revealing the complex drought impact mechanisms on ecosystem components; 2) providing continuous long-term drought related information at large scales; 3) presenting real-time drought information with high spatiotemporal resolution; 4) providing multiple lines of evidence of drought monitoring to improve modeling and prediction robustness; and 5) improving the accuracy of drought monitoring and assessment efforts. We specifically highlight that more mechanism-oriented drought studies that leverage a combination of sensors and techniques (e.g., optical, microwave, hyperspectral, LiDAR, and constellations) across a range of spatiotemporal scales are needed in order to progress and advance our understanding, characterization and description of drought in the future.
•Multi-sensor observations provide advantages in addressing knowledge gaps.•Drought related remote sensing datasets are identified for multi-sensor studies.•Key drought phenomena and mechanisms benefiting from multi-sensors are highlighted.•Recent advances for multi-sensor drought monitoring models are synthesized.•Challenges and opportunities using multi-sensors for drought studies are provided.
The establishment of the university English teaching evaluation system is to give full play to the guiding, diagnostic, and feedback role of evaluation, to realize the evaluation for teaching ...evaluation for learning, and to promote the overall development of students. In this paper, the drivers and pressures of teachers and students in the process of English teaching are taken as the basis of evaluation, and the evaluation index system of university English teaching is established in combination with the DPSIR model. Taking the English teaching data of Chinese universities from 2010 to 2023 as the research object, the entropy weighting method was used to calculate the weights of evaluation indexes, and the TOPSIS comprehensive evaluation model was combined to explore the comprehensive development level of university English teaching. The obstacle degree model was used to analyze the obstacle degree of university English teaching evaluation. It was found that the weight of the driving force subsystem in the evaluation system of university English teaching was 0.2036. The level of university English teaching increased nearly 1.3 times between 2010 and 2023. The highest cumulative degree of obstacle was the mean score of final English grades (R1), whose average degree of obstacle reached 18.15%. The construction of a university English teaching evaluation system requires teachers to optimize their teaching methods and enrich the teaching content so as to promote the internalization of students’ English knowledge and ensure a scientific and reasonable English teaching evaluation system.
With the continuous development of industry, environmental problems continue to worsen, of which the environmental problems caused by the traditional aviation industry are particularly serious, but ...there are many problems with electric aircraft that have not been solved. Therefore, this paper explores the realization of electric aviation by using advanced battery technology and nanomaterials. The study found that there are a variety of advanced battery technologies and nanomaterials that contribute to the realization of electric aviation, among which Multi-walled carbon nanotubes(MWCNT)/ graphene-based composite phase change material technology has considerable potential. It has excellent battery thermal management performance and excellent high-power density. However, MWCNT/ graphene-based composite phase change material technology also has shortcomings at present, such as the production process is complex and difficult to mass produce. Although there are still many challenges, this paper believes that these challenges will be solved to enable electric aviation using advanced battery technology and nanomaterials.
Abstract
Despite the growing interest in predicting global and regional trends in vegetation productivity in response to a changing climate, changes in water constraint on vegetation productivity ...(i.e., water limitations on vegetation growth) remain poorly understood. Here we conduct a comprehensive evaluation of changes in water constraint on vegetation growth in the extratropical Northern Hemisphere between 1982 and 2015. We document a significant increase in vegetation water constraint over this period. Remarkably divergent trends were found with vegetation water deficit areas significantly expanding, and water surplus areas significantly shrinking. The increase in water constraints associated with water deficit was also consistent with a decreasing response time to water scarcity, suggesting a stronger susceptibility of vegetation to drought. We also observed shortened water surplus period for water surplus areas, suggesting a shortened exposure to water surplus associated with humid conditions. These observed changes were found to be attributable to trends in temperature, solar radiation, precipitation, and atmospheric CO
2
. Our findings highlight the need for a more explicit consideration of the influence of water constraints on regional and global vegetation under a warming climate.
The maintenance of soil health in agro-ecosystems is essential for sustaining agricultural productivity. Through its positive impacts on various soil physical and biological processes, cover cropping ...can be an important component of sustainable agricultural production systems. However, the practice of cover cropping can be complex, and possible trade-offs between the benefits and side effects of cover crops have not been examined. To evaluate these benefits and potential trade-offs, we quantitatively synthesized different ecosystem services provided by cover crops (e.g., erosion control, water quality regulation, soil moisture retention, accumulation of soil organic matter and microbial biomass, greenhouse gas (GHG) emission, weed and pest control, as well as yield of the subsequent cash crop) using data from previous publications. We used a simple indicator (δ), defined as the ratio of an observed variable (i.e., ecosystem service) under cover crop and under fallow condition, to evaluate the impacts of cover crops on a given ecosystem service. Our results showed that cover crops provided beneficial ecosystem services in most cases, except for an increase in GHG emission (δCO2 = 1.46 ± 0.47 and δN2 O = 1.49 ± 1.22; x¯ ± SD) and in pest (nematode) incidence (δnematode abundance = 1.29 ± 1.61). It is also important to highlight that, in some cases, tillage could offset the extent of ecosystem service benefits provided by cover crops. Based on this synthesis, we argue that cover crops should be incorporated into modern agricultural practices because of the many environmental benefits they offer, particularly the maintenance of soil and ecosystem health. More importantly, there was generally an increase in cash crop yield with cover cropping (δyield = 1.15 ± 0.75), likely due to improvement in various soil processes. Despite its benefits, the complexity of cover crop management should not be overlooked, and site-specific factors such as climate, soil type, cover crop species and tillage practices must be considered in order to optimize the benefits of cover cropping. In addition to crop yield, detailed economic analyses are needed to calculate the direct (e.g., reduction in the amount of chemical fertilizer) and indirect monetary benefits (e.g., the improvement of soil quality) of cover crops. Such a comprehensive analysis could serve as incentive for producers to integrate cover crops into their management practices.
The appearance of the oldest pottery in the world is a major focus of Early Neolithic archaeology. So far, most discoveries of early pottery have occurred in South China, North China, the Russian Far ...East, Japan and Korea. The discovery of very thick, low-fired, fibre-tempered pottery dated from around 10,000 BP at the Houtaomuga Site, in Jilin Province, fills an important gap in the distribution of early pottery in northeast China. Based on multi-disciplinary research and an important series of dates, this article establishes the chronology of the early pottery remains discovered at the Houtaomuga Site and their morphological and technical characteristics, and sheds light on their function. Finally, the authors compare them to the other early pottery sherds discovered in the surrounding region, and throughout East Asia, in order to discuss the significance of this discovery and its implications for the subsistence mode developed in the northwest of the Jilin Province at the very beginning of the Neolithic.
Food legume crops play important roles in conservation farming systems and contribute to food security in the developing world. However, in many regions of the world, their production has been ...adversely affected by drought. Although water scarcity is a severe abiotic constraint of legume crops productivity, it remains unclear how the effects of drought co-vary with legume species, soil texture, agroclimatic region, and drought timing. To address these uncertainties, we collected literature data between 1980 and 2014 that reported monoculture legume yield responses to drought under field conditions, and analyzed this data set using meta-analysis techniques. Our results showed that the amount of water reduction was positively related with yield reduction, but the extent of the impact varied with legume species and the phenological state during which drought occurred. Overall, lentil (Lens culinaris), groundnut (Arachis hypogaea), and pigeon pea (Cajanus cajan) were found to experience lower drought-induced yield reduction compared to legumes such as cowpea (Vigna unguiculata) and green gram (Vigna radiate). Yield reduction was generally greater when legumes experienced drought during their reproductive stage compared to during their vegetative stage. Legumes grown in soil with medium texture also exhibited greater yield reduction compared to those planted on soil of either coarse or fine texture. In contrast, regions and their associated climatic factors did not significantly affect legume yield reduction. In the face of changing climate, our study provides useful information for agricultural planning and research directions for development of drought-resistant legume species to improve adaptation and resilience of agricultural systems in the drought-prone regions of the world.
Evapotranspiration (ET) is an important component of the global hydrological cycle. However, to what extent transpiration ratios (T/ET) are controlled by vegetation and the mechanisms of global‐scale ...T/ET variations are not clear. We synthesized all the published papers that measured at least two of the three components (E, T, and ET) and leaf area index (LAI) simultaneously. Nonlinear relationships between T/ET and LAI were identified for both the overall data set and agricultural or natural data subsets. Large variations in T/ET occurred across all LAI ranges with wider variability at lower LAI. For a given LAI, higher T/ET was observed during later vegetation growing stage within a season. We developed a function relating T/ET to the growing stage relative to the timing of peak LAI. LAI and growing stage collectively explained 43% of the variations in the global T/ET data set, providing a new way to interpret and model global T/ET variability.
Key Points
We reported the practical upper limit of vegetation control on T/ETFor a given leaf area, higher T/ET ratios occurred in the latter growing stage within a seasonGrowing stage and LAI explain 43% of the global T/ET variability
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