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This study investigates the utility of plant δ¹3C natural labeling in predicting the impacts of environmental shifts on carbon cycling within ecosystems, particularly focusing on paddy fields treated with maize (Zea maysL.) residues and biochar. Specifically, it examines how soil δ¹3C and the sources of soil organic carbon (SOC), respond in paddy fields (which cultivate C3plants like rice) when amended with maize residues, maize biochar, and silica‐enriched biochar (derived from C4plants). Conducted in the Fuzhou paddy fields, the experiment included control groups and treatment groups with maize residue (4 t ha⁻¹), maize biochar (4 t ha⁻¹), and silicon‐modified maize biochar (4 t ha⁻¹) during both the early and late rice growth periods. The results indicate that all soil treatments increased soil δ¹3C. The application of maize residues notably affected the δ¹3C of the upper soil profile (0–15 cm) differently from the deeper layers (15–30 cm), and it increased soil organic C more than biochar or silicon‐modified maize biochar. Soil available P (AP) and pH emerged as significant factors linking δ¹3C, influencing rice yield through changes in soil physicochemical properties. Unlike maize residues, which reduced rice yields, applications of biochar and silicon‐modified maize biochar increased rice yields. The latter, which was particularly effective in lowering SOC decomposition rates and addressing rice's silica needs, emerged as the preferred option. The study highlights maize biochar and silicon‐modified maize biochar as sustainable alternatives to maize residues for rice cultivation, enhancing soil fertility, carbon pool stability, and yields. New management of crop residues to improve crop soil quality in paddy fields is studied.New management of crop residues to improve rice yield is studied.The suitability of use of δ13C labeling methods for this type of research is determined.The relationship between diverse soil physicochemical properties with changes in soil organic carbon contents and quality is studied.The use of excessive industrial fertilizers should be avoided.

Resource demand by soil microorganisms critically influences microbial metabolism and then influences ecosystem resilience and multifunctionality. The ecological remediation of abandoned tailings is a topic of broad interest, yet our understanding of microbial metabolic status in restored soils, particularly at the aggregate scale, remains limited. This study investigated microbial resources within soil aggregates from revegetated tailings and applied a vector model of ecoenzymatic stoichiometry to examine how different vegetation patterns (grassland, forest, or bare land control) impact microbial resource limitation. Five-year vegetation restoration significantly elevated carbon (C) and nitrogen (N) concentrations and their stoichiometric ratios in soil aggregates (approximately 2-fold), although these increases were not translated to in the microbial biomass and its stoichiometry. The activities of C- and phosphorus (P)-acquiring extracellular enzymes in these aggregates increased substantially postvegetation, with the most pronounced escalation in macroaggregates (>0.25 mm). The vector model results indicated soil microbial metabolism was colimited by C and P, most acutely in microaggregates (<0.25 mm). This colimitation was exacerbated by monotypic vegetation cover but mitigated under diversified vegetation cover. Soil nutrient stoichiometric ratios in vegetation restoration controlled microbial resource limitation, overshadowing the impact of heavy metals. Our findings underscore that optimizing resource allocation within soil aggregates through strategic revegetation can enhance microbial metabolism in tailings, which advocates for the implementation of diverse vegetation covers as a viable strategy to improve the ecological development of degraded landscapes.

The rising frequency of infectious diseases under climate change poses an emerging threat to environmental and agricultural sustainability by consuming large quantities of materials. The demand for crops to produce personal protective equipment (PPE) competes for land and fertilizers, leads to cropland expansion, and accelerates climate change, but the ecological impacts remain unclear. Here we explore the impacts of pandemics on global warming, agricultural production, and biodiversity loss in an Earth system model by developing relationships between consumption of PPE and the rate of infection during COVID-19. Meeting the demand for PPE would increase production of cotton lint, corn, and natural rubber, which accelerates global warming by 0.2°C with 1.8% additional species losses by 2100. Our results suggest that the risks of public health, food security, climate change, and ecological integrity have been connected to each other, which should be considered when predicting the impacts of future pandemics.

The carbon (C), nitrogen (N) and phosphorus (P) stoichiometry of plant-soil systems is crucial to drive nutrient cycling in arid ecosystems. Although precipitation changes are increasingly affecting nutrient cycling with important feedbacks to ecosystem function, however, a mechanistic understanding of how the stoichiometry in plant-soil systems responds to precipitation changes in arid grasslands is still lacking. We conducted a 7-year field experiment with manipulative precipitation (ambient, ± 20%, ± 40% and ± 60%) to examine the effect of increased precipitation and drought on the stoichiometry of plant, litter, soil and soil microbe in an arid grassland in northern China. We also quantify the roles of plant composition, diversity and functional traits, soil properties and soil microbial diversity in determining the stoichiometry in plant-soil systems. Increased precipitation or drought did not affect soil stoichiometry. Increased precipitation increased litter C but drought decreased plant and litter C:N. Further, drought increased plant and litter N and microbial C content, as well as plant C:P and N:P, litter N:P and microbial C:N and C:P. Drought effects on C:P and N:P in plant and litter and on microbial C:N were mediated by leaf N content, while the effects on plant C:P and N:P were mediated by leaf C content. Additionally, plant height regulated the drought effects on microbial C:P. C:N:P stoichiometry in plant, litter and soil microbe is more sensitive to drought than increased precipitation and plant functional traits are critical for predicting nutrient cycling in arid grasslands under future drought scenarios.

Mature xerophytes access groundwater and minimize the risk of water and nutrient deficits in arid environments. However, how their young seedlings respond to the availability of water and nutrients before they reach groundwater is largely unknown. We investigated the effects of different drought regimes (controlled, medium-drought (MD), and severe-drought (SD)] and nitrogen (N; with or without) addition on biomass and physio-biochemical responses in Alhagi sparsifoliaseedlings. Both drought stresses significantly increased superoxide dismutase (O2•−), hydrogen peroxide (H2O2), malondialdehyde, and oxidized-glutathione in leaves and roots, thereby impairing growth and metabolism. Furthermore, there is a significant accumulation of fructose and glucose, but lower sucrose and starch, possibly due to higher sucrose synthase, α-amylase, β-amylase and hexokinase but lower sucrose phosphate synthase and fructokinase. Drought-stressed seedlings also displayed higher abscisic and, jasmonic acids, strigolactones, glucose-6-phosphate dehydrogenase (G-6-PDH), phosphoenolpyruvate carboxylase, O2•−-H2O2-scavenging enzymes, but lower gibberellin, cytokinin, and indole-acetic acid. However, N-addition quantifies the productivity of drought-stressed seedlings by improving the leaf relative water content (LRWC), biomass, chlorophyll-a, sucrose-synthesizing enzymes (SPP and SPS), and hormones. It also increased the G-6-PDH in stressed seedlings to satisfy the need for NADPH and reduced the sucrose and starch degrading enzymes, leading to higher starch and sucrose levels. Upregulation of O2•−-H2O2-scavenging enzymes under N-supply reduced lipid peroxidation and improved the ascorbate–glutathione redox states. N addition might be an effective strategy to improve drought resistance in A. sparsifoliaseedlings to manage and conserve its vegetation in hyper-arid conditions in the face of future climate change.

The soil priming effect (PE), defined as the modification of soil organic matter decomposition by labile carbon (C) inputs, is known to influence C storage in terrestrial ecosystems. However, how chronic nutrient addition, particularly in leguminous and non-leguminous forests, will affect PE through interaction with nutrient (e.g., nitrogen and phosphorus) availability is still unclear. Therefore, we collected soils from leguminous and non-leguminous subtropical plantations across a suite of historical nutrient addition regimes. We added 13C-labeled glucose to investigate how background soil nutrient conditions and microbial communities affect priming and its potential microbial mechanisms. Glucose addition increased soil organic matter decomposition and prompted positive priming in all soils, regardless of dominant overstory tree species or fertilizer treatment. In non-leguminous soil, only combined nitrogen and phosphorus addition led to a higher positive priming than the control. Conversely, soils beneath N-fixing leguminous plants responded positively to P addition alone, as well as to joint NP addition compared to control. Using DNA stable-isotope probing, high-throughput quantitative PCR, enzyme assays and microbial C substrate utilization, we found that positive PE was associated with increased microbial C utilization, accompanied by an increase in microbial community activity, nutrient-related gene abundance, and enzyme activities. Our findings suggest that the balance between soil available N and P effects on the PE,  was dependent on rhizosphere microbial community composition. Furthermore, these findings highlight the roles of the interaction between plants and their symbiotic microbial communities in affecting soil priming and improve our understanding of the potential microbial pathways underlying soil PEs.

China’s goal to achieve carbon (C) neutrality by 2060 requires scaling up photovoltaic (PV) and wind power from 1 to 10–15 PWh year−1(refs. 1–5). Following the historical rates of renewable installation1, a recent high-resolution energy-system model6and forecasts based on China’s 14th Five-year Energy Development (CFED)7, however, only indicate that the capacity will reach 5–9.5 PWh year−1by 2060. Here we show that, by individually optimizing the deployment of 3,844 new utility-scale PV and wind power plants coordinated with ultra-high-voltage (UHV) transmission and energy storage and accounting for power-load flexibility and learning dynamics, the capacity of PV and wind power can be increased from 9 PWh year−1(corresponding to the CFED path) to 15 PWh year−1, accompanied by a reduction in the average abatement cost from US$97 to US$6 per tonne of carbon dioxide (tCO2). To achieve this, annualized investment in PV and wind power should ramp up from US$77 billion in 2020 (current level) to US$127 billion in the 2020s and further to US$426 billion year−1in the 2050s. The large-scale deployment of PV and wind power increases income for residents in the poorest regions as co-benefits. Our results highlight the importance of upgrading power systems by building energy storage, expanding transmission capacity and adjusting power load at the demand side to reduce the economic cost of deploying PV and wind power to achieve carbon neutrality in China.

Global net land carbon uptake or net biome production (NBP) has increased during recent decades1. Whether its temporal variability and autocorrelation have changed during this period, however, remains elusive, even though an increase in both could indicate an increased potential for a destabilized carbon sink2,3. Here, we investigate the trends and controls of net terrestrial carbon uptake and its temporal variability and autocorrelation from 1981 to 2018 using two atmospheric-inversion models, the amplitude of the seasonal cycle of atmospheric CO2concentration derived from nine monitoring stations distributed across the Pacific Ocean and dynamic global vegetation models. We find that annual NBP and its interdecadal variability increased globally whereas temporal autocorrelation decreased. We observe a separation of regions characterized by increasingly variable NBP, associated with warm regions and increasingly variable temperatures, lower and weaker positive trends in NBP and regions where NBP became stronger and less variable. Plant species richness presented a concave-down parabolic spatial relationship with NBP and its variability at the global scale whereas nitrogen deposition generally increased NBP. Increasing temperature and its increasing variability appear as the most important drivers of declining and increasingly variable NBP. Our results show increasing variability of NBP regionally that can be mostly attributed to climate change and that may point to destabilization of the coupled carbon–climate system.

At present, a variety of vaccines have been approved, and existing antiviral drugs are being tested to find an effective treatment for coronavirus disease 2019 (COVID-19). However, no standardized treatment has yet been approved by the World Health Organization. The virally encoded chymotrypsin-like protease (3CLpro) from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which facilitates the replication of SARS-CoV in the host cells, is one potential pharmacological target for the development of anti-SARS drugs. Online search engines, such as Web of Science, Google Scholar, Scopus and PubMed, were used to retrieve data on the traditional uses of medicinal plants and their inhibitory effects against the SARS-CoV 3CLpro. Various pure compounds, including polyphenols, terpenoids, chalcones, alkaloids, biflavonoids, flavanones, anthraquinones and glycosides, have shown potent inhibition of SARS-CoV-2 3CLproactivity with 50% inhibitory concentration (IC50) values ranging from 2–44 µg/mL. Interestingly, most of these active compounds, including xanthoangelol E (isolated from Angelica keiskei), dieckol 1 (isolated from Ecklonia cava), amentoflavone (isolated from Torreya nucifera), celastrol, pristimerin, tingenone and iguesterin (isolated from Tripterygium regelii), tannic acid (isolated from Camellia sinensis), and theaflavin-3,3′-digallate, 3-isotheaflav1in-3 gallate and dihydrotanshinone I (isolated from Salvia miltiorrhiza), had IC50values of less than 15 µg/mL. Kinetic mechanistic studies of several active compounds revealed that their mode of inhibition was dose-dependent and competitive, with Kivalues ranging from 2.4–43.8 μmol/L. Given the significance of plant-based compounds and the many promising results obtained, there is still need to explore the phytochemical and mechanistic potentials of plants and their products. These medicinal plants could serve as an effective inexpensive nutraceutical for the general public to help manage COVID-19.

The potential of mitigation actions to limit global warming within 2 °C (ref. 1) might rely on the abundant supply of biomass for large-scale bioenergy with carbon capture and storage (BECCS) that is assumed to scale up markedly in the future2–5. However, the detrimental effects of climate change on crop yields may reduce the capacity of BECCS and threaten food security6–8, thus creating an unrecognized positive feedback loop on global warming. We quantified the strength of this feedback by implementing the responses of crop yields to increases in growing-season temperature, atmospheric CO2concentration and intensity of nitrogen (N) fertilization in a compact Earth system model9. Exceeding a threshold of climate change would cause transformative changes in social–ecological systems by jeopardizing climate stability and threatening food security. If global mitigation alongside large-scale BECCS is delayed to 2060 when global warming exceeds about 2.5 °C, then the yields of agricultural residues for BECCS would be too low to meet the Paris goal of 2 °C by 2200. This risk of failure is amplified by the sustained demand for food, leading to an expansion of cropland or intensification of N fertilization to compensate for climate-induced yield losses. Our findings thereby reinforce the urgency of early mitigation, preferably by 2040, to avoid irreversible climate change and serious food crises unless other negative-emission technologies become available in the near future to compensate for the reduced capacity of BECCS.

Anthropogenic inputs of nitrogen (N) and phosphorus (P) to terrestrial ecosystems alter soil nutrient cycling. However, the global‐scale responses of soil P fractions to N and P inputs and their underlying mechanisms remain elusive. We conducted a global meta‐analysis based on 818 observations of soil P fractions from 99 field N and P addition experiments in forest, grassland, and cropland ecosystems ranging from temperate to tropical zones. Our global meta‐analysis revealed distinct responses of soil P fractions to N and P enrichment. For studies using the Chang and Jackson inorganic (Pi) method, we found that high N addition promoted the transformation of immobile Pi fractions into Ferrum/Aluminum‐bound Pi and available Pi in surface soils through soil acidification. However, this acid‐induced transformation of Pi fractions by N addition was observed only in Calcium‐rich soils, while in acidic soils, further acidification led to increase P binding. In contrast, additions of P alone or combined with N significantly increased all soil Pi fractions. Regarding the Hedley P fractions, N addition generally decreased labile organic P by enhancing soil acid phosphatase activity. The responses of other P fractions were influenced by soil pH, fertilization rates, ecosystem type, and other factors. P addition increased most soil P fractions. Overall, both P fractionation methods consistently demonstrate that N inputs deplete soil P and accelerate P cycling, while P inputs increase most soil P fractions, alleviating P limitation. These findings are crucial for predicting the effects of future atmospheric N and P deposition on P cycling processes. Human activities have increased the amount of nitrogen (N) and phosphorus (P) in the environment, which has led to changes in the soil nutrients cycle. This study examined the global‐scale responses of soil P fractions to N and P inputs using a data set from 99 field experiments worldwide. The findings revealed distinct responses of soil P fractions to N and P enrichment. High N input resulted in the transformation of immobile inorganic P (Pi) fractions into available Pi in surface soils. This transformation was observed in calcium‐rich soils due to soil acidification. In contrast, in acidic soils, the acidification led to increased Pi binding. Moreover, N input generally decreased labile organic P, potentially by enhancing soil enzyme activity. Addition of P alone or combined with N significantly increased soil P fractions. These findings have important implications for predicting the effects of future N and P deposition on P cycling processes in the terrestrial ecosystems and understanding the impacts of nutrient enrichment on soil carbon storage and eutrophication. Nitrogen inputs can accelerate phosphorus (P) transformation in Calcium‐rich soils but promote P binding in acidic soilsSoil acidification reduces inorganic P bioavailability by increasing the P fixation of Ferrum and Alumiium oxidePhosphorus input increases soil labile, moderately labile, and occluded inorganic P, enhancing soil available P Nitrogen inputs can accelerate phosphorus (P) transformation in Calcium‐rich soils but promote P binding in acidic soils Soil acidification reduces inorganic P bioavailability by increasing the P fixation of Ferrum and Alumiium oxide Phosphorus input increases soil labile, moderately labile, and occluded inorganic P, enhancing soil available P

Imbalanced anthropogenic inputs of nitrogen (N) and phosphorus (P) have significantly increased the ratio between N and P globally, degrading ecosystem productivity and environmental quality. Lakes represent a large global nutrient sink, modifying the flow of N and P in the environment. It remains unknown, however, the relative retention of these two nutrients in global lakes and their role in the imbalance of the nutrient cycles. Here we compare the ratio between P and N in inflows and outflows of more than 5,000 lakes globally using a combination of nutrient budget model and generalized linear model. We show that over 80% of global lakes positively retain both N and P, and almost 90% of the lakes show preferential retention of P. The greater retention of P over N leads to a strong elevation in the ratios between N and P in the lake outflow, exacerbating the imbalance of N and P cycles unexpectedly and potentially leading to biodiversity losses within lakes and algal blooms in downstream N-limited coastal zones. The management of N or P in controlling lake eutrophication has long been debated. Our results suggest that eutrophication management that prioritizes the reduction of P in lakes—which causes a further decrease in P in outflows—may unintentionally aggravate N/P imbalances in global ecosystems. Our results also highlight the importance of nutrient retention stoichiometry in global lake management to benefit watershed and regional biogeochemical cycles.

Assessing global progress on human adaptation to climate change is an urgent priority. Although the literature on adaptation to climate change is rapidly expanding, little is known about the actual extent of implementation. We systematically screened >48,000 articles using machine learning methods and a global network of 126 researchers. Our synthesis of the resulting 1,682 articles presents a systematic and comprehensive global stocktake of implemented human adaptation to climate change. Documented adaptations were largely fragmented, local and incremental, with limited evidence of transformational adaptation and negligible evidence of risk reduction outcomes. We identify eight priorities for global adaptation research: assess the effectiveness of adaptation responses, enhance the understanding of limits to adaptation, enable individuals and civil society to adapt, include missing places, scholars and scholarship, understand private sector responses, improve methods for synthesizing different forms of evidence, assess the adaptation at different temperature thresholds, and improve the inclusion of timescale and the dynamics of responses.

Coastal reservoirs are potentially CH4emission hotspots owing to their biogeochemical role as the sinks of anthropogenic carbon and nutrients. Yet, the fine-scale spatial variations in CH4concentrations and fluxes in coastal reservoirs remain poorly understood, hampering an accurate determination of reservoir CH4budgets. In this study, we examined the spatial variability of diffusive CH4fluxes and their drivers at a subtropical coastal reservoir in southeast China using high spatial resolution measurements of dissolved CH4concentrations and physicochemical properties of the surface water. Overall, this reservoir acted as a consistent source of atmospheric CH4, with a mean diffusive flux of 16.1 μmol m–2h–1. The diffusive CH4flux at the reservoir demonstrated considerable spatial variations, with the coefficients of variation ranging between 199 and 426% over the three seasons. The shallow water zone (comprising 23% of the reservoir area) had a disproportionately high contribution (56%) to the whole-reservoir diffusive CH4emissions. Moreover, the mean CH4flux in the sewage-affected sectors was significantly higher than that in the nonsewage-affected sectors. The results of bootstrap analysis further showed that increasing the sample size from 10 to 100 significantly reduced the relative standard deviation of mean diffusive CH4flux from 73.7 to 3.4%. Our findings highlighted the role of sewage in governing the spatial variations in reservoir CH4emissions and the importance of high spatial resolution data to improve the reliability of flux estimates for assessing the contribution of reservoirs to the regional and global CH4budgets.

Climate change is expected to alter the frequency and intensity of drying and rewetting cycles, impacting water availability and consequently soil nutrient availability. However, the effects of these fluctuations on the chemical speciation and bioavailability of phosphorus (P) in soil with or without desert species remain uncertain. We conducted a pot experiment involving bare soil and two desert species (Alhagi sparsifoliaand Calligonum mongolicum) to determine the short-term impacts of drought (no water supply), drying-rewetting-1 (D-RW1, high frequency of low water amounts), and drying-rewetting-2 (D-RW2, low frequency of high-water amounts) treatments on soil Hedley-P pools, plant P concentration and biomass accumulation. Results demonstrated that the presence of plants significantly increased soil labile-P and organic P (Po) concentrations by 60–150% and 1–68%, respectively, compared to bare soil. Both D-RW1 and D-RW2 treatments significantly increased soil dissolved organic carbon concentration by 2–35% relative to the drought treatment. Moreover, soil resin-P and NaHCO3-Pi concentrations under Alhagi sparsifoliain D-RW1 treatment significantly increased by 31% and 75%, respectively, when compared to the drought treatment, with NaHCO3-Po and NaOH-Po concentrations under D-RW2 treatment rising by 14% and 32%, respectively. Furthermore, D-RW2 treatment significantly increased leaf P concentration and biomass compared to D-RW1 and drought treatments. Overall, compared to drought treatment, frequent low-intensity drying-rewetting cycles enhanced soil Pi turnover, whereas infrequent high-intensity drying-rewetting cycles increased Po turnover and P bioavailability. These findings will inform better water management strategies for desertification restoration in hyper-arid desert ecosystems.

•Acidification suppresses microbial N retention by reducing its biomass and activity.•Role of SOM in N retention is elusive as altered SOM leaching and mineralization.•Damage of lattice of 2:1 minerals reduces soil retention of fixed NH4+.•Macroaggregate breakup and microaggregate binding of SOM diversely alter N retention.•Acid-tolerant plants produce high-N but low degradable litter to enhance N retention.

•Plants respond differently to repeated stress than to a single stress•Alhagi sparsifoliaadapts different strategies to cope with drought stress•Drought-primed seedlings had a lower oxidative status than non-primed•Stress memory helped A. sparsifoliaseedlings to overcome subsequent stress

Microplastics (MPs) contamination presents a significant global environmental challenge, with its potential to influence soil carbon (C) dynamics being a crucial aspect for understanding soil C changes and global C cycling. This meta-analysis synthesizes data from 110 peer-reviewed publications to elucidate the directional, magnitude, and driving effects of MPs exposure on soil C dynamics globally. We evaluated the impacts of MPs characteristics (including type, biodegradability, size, and concentration), soil properties (initial pH and soil organic C [SOC]), and experimental conditions (such as duration and plant presence) on various soil C components. Key findings included the significant promotion of SOC, dissolved organic C, microbial biomass C, and root biomass following MPs addition to soils, while the net photosynthetic rate was reduced. No significant effects were observed on soil respiration and shoot biomass. The study highlights that the MPs concentration, along with other MPs properties and soil attributes, critically influences soil C responses. Our results demonstrate that both the nature of MPs and the soil environment interact to shape the effects on soil C cycling, providing comprehensive insights and guiding strategies for mitigating the environmental impact of MPs.

Dissimilatory nitrate/nitrite reduction processes play an important role in controlling nitrogen loading in river environments. However, the relative importance of climatic temperature regime and biogeochemical controls to dissimilatory nitrate/nitrite reduction processes remains unclear. We used nitrogen isotope tracer approach to investigate geographical variabilities of denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) in river sediments from temperate to tropical climates of China. Denitrification, anammox, and DNRA varied greatly across the climatic gradient, with potential rates of 1.47–25.7, 0.54–3.4, and 0.15–7.17 nmol N g−1h−1, respectively. Mean measured rates throughout the sampling sites were 9.73 nmol N g−1h−1for denitrification, 1.29 nmol N g−1h−1for anammox, and 1.61 nmol N g−1h−1for DNRA. Denitrification and DNRA rates increased significantly from temperate to tropical climates, while no significantly spatial difference was observed for anammox rates along the climatic gradient. Mean annual temperature, total organic carbon, dissolved organic carbon, pH, NH4+, NO3–, C/N, Fe2+, and functional genes were the crucial factors affecting denitrification, anammox, and DNRA. High dissolved organic carbon and NO3–availability determined nitrogen removal capacity in river sediments. Mean annual temperature was the most important factor explaining the geographical variances of denitrification and DNRA, while the critical predictor of anammox variance was sediment pH along the climatic gradient. Our results highlight that biogeochemical controls and climatic temperature regime are important coregulators affecting the geographical variabilities of dissimilatory nitrate/nitrite reduction processes in river sediments at the continental‐scale variation. Denitrification and DNRA rates increased from temperate to tropical climatesDenitrification, anammox, and DNRA rates correlated with sediment characteristicsTemperature explained mostly variances of denitrification and DNRA, and sediment variables were the critical predictors of anammox variance

Microorganisms are major drivers of elemental cycling in the biosphere. Determining the abundance of microbial functional traits involved in the transformation of nutrients, including carbon (C), nitrogen (N), phosphorus (P) and sulfur (S), is critical for assessing microbial functionality in elemental cycling. We developed a high-throughput quantitative-PCR-based chip, Quantitative microbial element cycling (QMEC), for assessing and quantifying the genetic potential of microbiota to mineralize soil organic matter and to release C, N, P and S. QMEC contains 72 primer pairs targeting 64 microbial functional genes for C, N, P, S and methane metabolism. These primer pairs were characterized by high coverage (average of 18–20 phyla covered per gene) and sufficient specificity (>70% match rate) with a relatively low detection limit (7–102 copies per run). QMEC was successfully applied to soil and sediment samples, identifying significantly different structures, abundances and diversities of the functional genes (P<0.05). QMEC was also able to determine absolute gene abundance. QMEC enabled the simultaneous qualitative and quantitative determination of 72 genes from 72 samples in one run, which is promising for comprehensively investigating microbially mediated ecological processes and biogeochemical cycles in various environmental contexts including those of the current global change.

Hydroxylamine (NH2OH) is an important intermediate of nitrification and can contribute to nitrous oxide (N2O) production through abiotic and biotic pathways. NH2OH concentrations and associated biogeochemical controls in estuarine water and sediments remain poorly understood. Here, we investigated spatial and seasonal variability of NH2OH concentrations in water and sediments and determined the correlation between NH2OH and N2O in the Min River Estuary off southeast China. NH2OH concentrations in water and sediments ranged from 0.22 to 140 nmol N L−1and from 0.17 to 9.22 μmol N kg−1, respectively. High differences in NH2OH concentrations between sediments and water could drive diffusion of NH2OH from sediments to water. NH2OH concentrations were significantly higher in warm than in cold seasons, suggesting that NH2OH production is highly dependent on temperature. Upper estuary (urban section) showed higher NH2OH concentrations in water and sediments, followed by lower and middle estuary. Temperature, dissolved oxygen, and pH were the major factors driving spatial and seasonal variability in NH2OH concentrations. Water dissolved N2O concentrations and air‐water N2O fluxes varied between 1.52 and 55.9 nmol N L−1and between −57.7 and 78.7 nmol N m−2h−1, respectively, with switches from net sinks in spring to net sources of N2O emissions in other seasons. Although N2O concentrations and fluxes were linearly correlated with water NH2OH concentrations, the contribution of NH2OH to N2O production could not be addressed. Therefore, the dynamics of NH2OH concentrations are a useful tool to assess potential production and consumption pathways of N2O in estuarine and coastal ecosystems. Hydroxylamine (NH2OH) can produce nitrous oxide (N2O) through abiotic and biological processes in estuarine and coastal environments. This study investigated seasonal and spatial variability of NH2OH concentrations in water and sediments and determined the correlation between N2O and NH2OH concentrations in the Min River Estuary off southeast China. NH2OH concentrations in water and sediments varied significantly across the seasons and along this estuary, with higher concentrations in warm seasons and in upper estuary. High temperature could cause low dissolved oxygen and low pH that stimulate nitrification to produce more NH2OH and NO2−, which increased NH2OH oxidation and nitrifier‐denitrification to yield more N2O. N2O concentrations and fluxes were significantly related to NH2OH concentrations, suggesting that NH2OH could be a relevant source of N2O emissions. This study shows the effect of NH2OH production in the emissions of N2O, providing insights which can be used to better constrain the projections on future emissions of this gas in estuarine environments. Hydroxylamine concentrations in water and sediments were significantly higher in warm than in cold seasonsAmmonium and temperature were the major drivers of spatiotemporal variability in hydroxylamine concentrationsHydroxylamine and nitrous oxide concentrations in water and sediments were strongly correlated Hydroxylamine concentrations in water and sediments were significantly higher in warm than in cold seasons Ammonium and temperature were the major drivers of spatiotemporal variability in hydroxylamine concentrations Hydroxylamine and nitrous oxide concentrations in water and sediments were strongly correlated

Plastic film mulching and urea nitrogen fertilization are widely used in agricultural ecosystems, but both their long-term use may leave a negative legacy on crop growth, due to deleterious effects of plastic and microplastic accumulation and acidification in soil, respectively. Here, we stopped covering soil with a plastic film in an experimental site that was previously covered for 33 years and compared soil properties and subsequent maize growth and yield between plots that were previously and never covered with the plastic film. Soil moisture was about 5–16% higher at the previously mulched plot than at the never-mulched plot, but NO3–content was lower for the former when with fertilization. Maize growth and yield were generally similar between previously and never-mulched plots. Maize had an earlier dough stage (6–10 days) in previously mulched compared to never-mulched plots. Although plastic film mulching did add substantial amounts of film residues and microplastic accumulation into soils, it did not leave a net negative legacy (given the positive effects of the mulching practice in the first place) for soil quality and subsequent maize growth and yield, at least as an initial effect in our experiment. Long-term urea fertilization resulted in a pH decrease of about 1 unit, which bring a temporary maize P deficiency occurring in early stages of growth. Our data add long-term information on this important form of plastic pollution in agricultural systems.

Organic cultivation methods would be a good alternative to conventional cultivation, avoiding the use of industrial fertilizer and reducing the risk of eutrophication, but its impacts on soil elemental composition and stoichiometry warrants to be clearly stated. This study was conducted to determine the effects of long‐term organic cultivation on soil elemental composition, stoichiometry, and C storing capacity and CO2emissions in the plant‐soil systems of jasmine (Jasminumspp.) and tea [Camellia sinensis(L.) Ktze.] plantations in Fujian and other regions in China. We examined the impact of organic cultivation on the concentrations, contents and stoichiometric relationships among C, N, P, and K. Organic cultivation was associated with lower plant N and P concentrations, and P mineralomasses and with higher total plant C/N, C/P, C/K, and N/P ratios and higher soil N and P concentrations and contents at some depths. Organic cultivation was thus associated with a shift of P from plants to soil and with a higher nutrient‐use efficiency in biomass production, mainly of P. Soil CO2emissions were higher under organic cultivation, but the soil was able to accumulate more C with no changes in C storage in plant biomass, suggesting that organic cultivation could increase the overall C sequestration, thereby mitigating climate change and enhancing soil nutrient content. Our results thus showed that the organic cultivation of jasmine and tea in Fujian can improve soil fertility and C accumulation, reduce the use of industrial fertilizers and phytosanitary products, and improve product quality without loss of economical profits. Core Ideas Jasmine and tea cultivation have a long history in Fujian and other regions in ChinaWe explored their organic cultivation for the future viability of these cropsOrganic cultivation increased nutrient‐use efficiencySoil was able to accumulate more C under organic cultivationOrganic cultivation improved soil fertility without affecting economic profits Jasmine and tea cultivation have a long history in Fujian and other regions in China We explored their organic cultivation for the future viability of these crops Organic cultivation increased nutrient‐use efficiency Soil was able to accumulate more C under organic cultivation Organic cultivation improved soil fertility without affecting economic profits

Long‐term patterns of dissolved oxygen (DO) in estuarine and coastal waters remain poorly understood. Here we summarized DO concentrations and analyzed the crucial drivers of hypoxia in northwestern and southern Hong Kong and Mirs Bay over the past three decades. Deoxygenation was weak in the bottom water in northwestern Hong Kong, although DO was consistently undersaturated, whereas the annual minimum DO in the bottom water exhibited a significant decrease in southern Hong Kong (−0.06 ± 0.01 mg L−1yr−1) and Mirs Bay (−0.10 ± 0.02 mg L−1yr−1). Seasonal hypoxia in the bottom water was accompanied by supersaturated DO and high Chl‐a in surface waters of southern Hong Kong, indicating a crucial role of local extensive productivity in the oxygen depletion of the bottom water. The rapid deoxygenation was also attributed to the water stratification preventing oxygen replenishment in southern Hong Kong and the predeoxygenation of bottom water retained in Mirs Bay. The dissolved inorganic nitrogen concentrations have increased from 1 to 3 mg N L−1, which increased the primary productivity contributing to the decrease in water DO over the past three decades. Therefore, these results suggest that biological oxygen consumption and seasonal stratification are mainly driving the formation and maintenance of hypoxia in the Pearl River Estuary and adjacent areas. We compared dissolved oxygen (DO) concentrations and the driving factors of hypoxia between northwestern and southern Hong Kong and Mirs Bay. Deoxygenation was weak in the bottom layer in northwestern Hong Kong, although the DO was consistently undersaturated, whereas a rapid decrease in the annual minimum DO was observed in the bottom layer in southern Hong Kong and Mirs Bay. The seasonal DO depletion and/or hypoxia in the bottom water was accompanied by supersaturated DO and high Chl‐a in surface water in southern Hong Kong, indicating local excessive productivity in triggering oxygen depletion. The predeoxygenation of bottom water and long water residence time have contributed to the deoxygenation in Mirs Bay. Water stratification could exacerbate hypoxia by preventing oxygen replenishment from the surface to the bottom layers. The upwelling water from the South China Sea and/or Kuroshio contributed inappreciably to the significant deoxygenation in southern Hong Kong and Mirs Bay. These results suggest that enhanced productivity and oxygen consumption, combined with stratification and currents, are increasingly driving hypoxia in the Pearl River Estuary and adjacent areas. Nutrients, physical and biological factors affected seasonal fluctuation of DO around Hong Kong watersThe annual minimum dissolved oxygen has declined over a period of 30 yearsMirs Bay will become a potential zone of hypoxia in the Pearl River Estuary Nutrients, physical and biological factors affected seasonal fluctuation of DO around Hong Kong waters The annual minimum dissolved oxygen has declined over a period of 30 years Mirs Bay will become a potential zone of hypoxia in the Pearl River Estuary

A 6‐yr experiment in drought manipulation was conducted in a Quercus ilexL. Mediterranean forest to simulate the drought conditions projected for the coming decades. We investigated the effects of those drought conditions on soil urease, protease, and β‐glucosidase activities and the changes in C and N stocks in soil, leaves, and leaf litter. Elimination of runoff and rainfall resulted in lower soil water content than in control soils in autumn, winter, and spring (27, 61, and 53%, respectively). In soils subjected to runoff plus partial rainfall elimination, urease activities were reduced by 25% in autumn, winter, and spring; soil protease activities by 33% in winter and spring; and β‐glucosidase by 25 to 30% in summer and spring. Drought reduced the C/N ratio of the leaf litter of the dominant species, Q. ilex, by 11%, indicating a decrease in N remobilization before leaf fall. We therefore did not observe an increase in the C/N concentration ratio in litter and soil as we had expected. Drought decreased N availability in spring, the growing season, by reducing soil NO3−concentration. The reduction in enzyme activities in the drought‐affected soils was mainly due to the prolonged decrease in water availability and, to a lesser extent, to current soil water availability, mainly in summer, and to changes in the nutritional quality of the enzyme substrate. The observed drop in soil enzyme activity can contribute to a decrease in the amount of N liberated and consequently to a decline in the plant N capture, which was observed in some community species such as Arbutus unedoL.

Abstract: We tested in the field the hypothesis that the specialist butterfly Euphydryas aurinia (Lepidoptera: Nymphalidae, Melitaeinae) lays eggs on leaves of Lonicera implexa (Caprifoliaceae) plants with greater iridoid concentrations. We conducted our investigations in a Mediterranean site by analyzing leaves with and without naturally laid egg clusters. There were no significant differences in iridoid glycoside concentrations between leaves from plants that did not receive eggs and the unused leaves from plants receiving eggs, a fact that would seem to indicate that E. aurinia butterflies do not choose plants for oviposition by their iridoid content. However, the leaves of L. implexa that bore egg clusters had dramatically greater (over 15-fold) concentrations of iridoid glycosides than the directly opposite leaves on the same plant. These huge foliar concentrations of iridoids (15% leaf dry weight) may provide specialist herbivores with compounds that they either sequester for their own defense or use as a means of avoiding competition for food from generalist herbivores. Nevertheless, it may still be possible that these high concentrations are detrimental to the herbivore, even if the herbivore is a specialist feeder on the plant.

Abstract:We manipulated nutrient availability and competing vegetation to investigate the phenotypic plasticity of leaf morphology and nutrient content of saplings and seedlings of the evergreen holm oak Quercus ilexsubsp. ballotain response to nutrient pulses. Different factorial experimental designs were established with N and/or P pulse fertilization as factors in a field experiment in Catalonia (northeast Spain) and with P fertilization, soil type, and competitive situation as factors in a pot experiment. In the field, P fertilization decreased leaf mass per area (LMA) 9–13% in the 3 y following the fertilization application. No significant effect was observed from variations in N supply in any leaf cohort. In the pot experiment, P fertilization increased the leaf size, pre-dawn leaf water content, and root growth and decreased the LMA. P fertilization strongly increased P leaf concentrations, as in the field experiment. Neighbour competition induced increases in LMA in the second leaf cohort and in leaf density and size in both leaf cohorts; it also reduced root growth and tended to increase P leaf concentrations. Soil type had a significant effect on individual leaf area, leaf mass, and LMA, the latter being higher in siliceous soils than in calcareous and artificial soils. The pattern of change in leaf thickness across the different soil types was the opposite of that for leaf P concentrations, P contents per unit of leaf area, and leaf density. These results point to a morphological leaf plasticity in response to P availability, competitive situation, and soil type. The relations between the changes in leaf morphology, leaf nutrient content, root growth, and pre-dawn leaf water content changed depending on the factor that induced them. However, leaf morphological traits changed in combination with other plant traits such as root growth and nutrient contents in order to balance resource availability and production capacity under different environmental conditions, such as changing degrees of neighbour competition or water availability. This plasticity of sclerophyllous leaf traits in response to nutrient pulses makes Quercus ilexsubsp. ballotawell suited to adapt to the unpredictable changes and stress situations likely to result from current and immediate future climate and other changes in the Mediterranean region.

The global socio‐economic and agricultural expansion is accompanied by large inputs of nitrogen (N) and phosphorus (P) on land and by a serious alteration of the water cycle and water quality. The Mediterranean basin represents a paradigmatic region to study the entangled nutrient and water challenges because the region, where many of the world's climatic and socio‐economic gradients are present, is predicted to suffer severe water stress in the coming decades yet at the same time agricultural intensification and population are increasing in many rim countries. We here describe the biogeochemical budgets of N and P in 549 river basins for the 2000–2009 period, analyzing how the climatic gradient and water management practices affect the fluxes of N and P and their stoichiometric ratios. Average land inputs are 3,600 kg N km−2yr−1and 470 kg P km−2yr−1, with a significant variation between basins (>100 times) closely related to the stage of agricultural intensification. Moreover, the combination of aridity and water regulation can strongly alter the final balances, not only by changing the export of nutrients by rivers (riverine export is ca. 10% for N and 8% for P in arid basins), but also decoupling the N:P ratios between terrestrial and freshwater compartments. We show how climatic features affect the export of N and P by rivers throughout a broad range of conditions, from wet temperate to aridIn arid environments water management plays a key role increasing inland retention, particularly for NThe association between climate and water management affects asymmetrically the fluxes of N and P and the N:P ratios in water and soils We show how climatic features affect the export of N and P by rivers throughout a broad range of conditions, from wet temperate to arid In arid environments water management plays a key role increasing inland retention, particularly for N The association between climate and water management affects asymmetrically the fluxes of N and P and the N:P ratios in water and soils

Lockdown measures are essential to containing the spread of coronavirus disease 2019 (COVID-19), but they will slow down economic growth by reducing industrial and commercial activities. However, the benefits of activity control from containing the pandemic have not been examined and assessed. Here we use daily carbon dioxide (CO2) emission reduction in China estimated from statistical data for energy consumption and satellite data for nitrogen dioxide (NO2) measured by the Ozone Monitoring Instrument (OMI) as an indicator for reduced activities consecutive to a lockdown. We perform a correlation analysis to show that a 1% day−1decrease in the rate of COVID-19 cases is associated with a reduction in daily CO2emissions of 0.22% ± 0.02% using statistical data for energy consumption relative to emissions without COVID-19, or 0.20% ± 0.02% using satellite data for atmospheric column NO2. We estimate that swift action in China is effective in limiting the number of COVID-19 cases <100,000 with a reduction in CO2emissions of up to 23% by the end of February 2020, whereas a 1-week delay would have required greater containment and a doubling of the emission reduction to meet the same goal. By analyzing the costs of health care and fatalities, we find that the benefits on public health due to reduced activities in China are 10-fold larger than the loss of gross domestic product. Our findings suggest an unprecedentedly high cost of maintaining activities and CO2emissions during the COVID-19 pandemic and stress substantial benefits of containment in public health by taking early actions to reduce activities during the outbreak of COVID-19.