AbstractFuture phosphorus (P) shortages could seriously affect terrestrial productivity and food security. We investigated the changes in topsoil available P (AP) and total P (TP) in China's forests, grasslands, paddy fields, and upland croplands during the 1980s–2010s based on substantial repeated soil P measurements (63,220 samples in the 1980s, 2000s, and 2010s) and machine learning techniques. Between the 1980s and 2010s, total soil AP stock increased with a small but significant rate of 0.13 kg P ha−1 year−1, but total soil TP stock declined substantially (4.5 kg P ha−1 year−1) in the four ecosystems. We quantified the P budgets of soil–plant systems by harmonizing P fluxes from various sources for this period. Matching trends of soil contents over the decades with P budgets and fluxes, we found that the P‐surplus in cultivated soils (especially in upland croplands) might be overestimated due to the great soil TP pool compared to fertilization and the substantial soil P losses through plant uptake and water erosion that offset the P additions. Our findings of P‐deficit in China raise the alarm on the sustainability of future biomass production (especially in forests), highlight the urgency of P recycling in croplands, and emphasize the critical role of country‐level basic data in guiding sound policies to tackle the global P crises.

Agricultural soils play a dual role in regulating the Earth's climate by releasing or sequestering carbon dioxide (CO2 ) in soil organic carbon (SOC) and emitting non-CO2 greenhouse gases (GHGs) such as nitrous oxide (N2 O) and methane (CH4 ). To understand how agricultural soils can play a role in climate solutions requires a comprehensive assessment of net soil GHG balance (i.e., sum of SOC-sequestered CO2 and non-CO2 GHG emissions) and the underlying controls. Herein, we used a model-data integration approach to understand and quantify how natural and anthropogenic factors have affected the magnitude and spatiotemporal variations of the net soil GHG balance in U.S. croplands during 1960-2018. Specifically, we used the dynamic land ecosystem model for regional simulations and used field observations of SOC sequestration rates and N2 O and CH4 emissions to calibrate, validate, and corroborate model simulations. Results show that U.S. agricultural soils sequestered Tg CO2 -C year-1 in SOC (at a depth of 3.5 m) during 1960-2018 and emitted Tg N2 O-N year-1 and Tg CH4 -C year-1 , respectively. Based on the GWP100 metric (global warming potential on a 100-year time horizon), the estimated national net GHG emission rate from agricultural soils was Tg CO2 -eq year-1 , with the largest contribution from N2 O emissions. The sequestered SOC offset ~28% of the climate-warming effects resulting from non-CO2 GHG emissions, and this offsetting effect increased over time. Increased nitrogen fertilizer use was the dominant factor contributing to the increase in net GHG emissions during 1960-2018, explaining ~47% of total changes. In contrast, reduced cropland area, the adoption of agricultural conservation practices (e.g., reduced tillage), and rising atmospheric CO2 levels attenuated net GHG emissions from U.S. croplands. Improving management practices to mitigate N2 O emissions represents the biggest opportunity for achieving net-zero emissions in U.S. croplands. Our study highlights the importance of concurrently quantifying SOC-sequestered CO2 and non-CO2 GHG emissions for developing effective agricultural climate change mitigation measures.

AbstractWater governance determines “who gets water, when, and how” in most large river basins. Shifts in water governance regimes from natural to social‐ecological or “hydrosocial” carry profound implications for human wellbeing; identifying regime changes in water governance is critical to navigating social‐ecological transitions and guiding sustainability. We characterized water governance along with the three main aspects—stress, purpose, and allocation—to develop a quantitative integrated water governance index (IWGI) at a basin scale. Applying the IWGI to the rapidly changing Yellow River Basin (YRB) in China clarifies shifts in water governance between massive supply, transformation governance, and adaptation‐oriented regimes. In the YRB, the underlying causes of regime shifts were increasing water supply and demand before the governance transformation and re‐allocation and regulation after the change. The IWGI offers a comprehensive and straightforward approach to linking water governance regimes to sustainability, providing valuable insights into hydrosocial transitions.

The frequency, intensity, and duration of extreme droughts, with devastating impacts on tree growth and survival, have increased with climate change over the past decades. Assessing growth resistance and resilience to drought is a crucial prerequisite for understanding the responses of forest functioning to drought events. However, the responses of growth resistance and resilience to extreme droughts with different durations across different climatic zones remain unclear. Here, we investigated the spatiotemporal patterns in growth resistance and resilience in response to extreme droughts with different durations during 1901-2015, relying on tree-ring chronologies from 2389 forest stands over the mid- and high-latitudinal Northern Hemisphere, species-specific plant functional traits, and diverse climatic factors. The findings revealed that growth resistance and resilience under 1-year droughts were higher in humid regions than in arid regions. Significant higher growth resistance was observed under 2-year droughts than under 1-year droughts in both arid and humid regions, while growth resilience did not show a significant difference. Temporally, tree growth became less resistant and resilient to 1-year droughts in 1980-2015 than in 1901-1979 in both arid and humid regions. As drought duration lengthened, the predominant impacts of climatic factors on growth resistance and resilience weakened and instead foliar economic traits, plant hydraulic traits, and soil properties became much more important in both climatic regions; in addition, such trends were also observed temporally. Finally, we found that most of the Earth system models (ESMs) used in this study overestimated growth resistance and underestimated growth resilience under both 1-year and 2-year droughts. A comprehensive ecophysiological understanding of tree growth responses to longer and intensified drought events is urgently needed, and a specific emphasis should be placed on improving the performance of ESMs.

AbstractOptimal phosphorus (P) levels in lateritic soils are key for sustainable crop production. However, the effect of various fertilizers on soil phosphorus pools, crop phosphorus uptake and crop yields remains unclear. This study investigated the effect of different fertilizer application strategies on plant growth and soil P fractions and determined the contribution of biotic and abiotic factors to insoluble P release. We found that resin‐P, NaHCO3‐P and NaOH‐P represented the primary active P pools in the lateritic soil, contributing 59.8% of the total P in conventional fertilizer application (CF), with Fe/Al‐bound P (NaOH‐P) being 42.1% of the active P pool. Combining Nangbowang (NBW), a microbial organic fertilizer inoculated with Bacillus subtilis (≥2 × 107 million CFU g−1), with reduced chemical fertilizer (NBW + CR) increased soil P availability and promoted the release of Fe/Al‐bound P and residual‐P, decreasing the Fe/Al‐bound P to 21.7%. Soil biological factors mainly influenced the P transformation process. With the consumption of soil active P, NBW bio‐organic fertilizer enhanced the niche filtration of P‐solubilizing bacterial communities (Gemmatimonadetes, Sphingomonas and Halomonas), altered the soil functional microbial community structure and promoted P form conversion. The NBW + CR treatment also enhanced nitrogen and P nutrient uptake by pepper plants (Capsicum annuum), with increased total P concentrations in pepper fruit and stem, and improved crop yield. NBW increased active P concentrations in the soil and promoted Fe/Al‐P release and transformation by impacting autochthonous microbes involved in the conversion of P chemical species. These results can guide the improvement of P availability and release in lateritic red soils using bio‐organic fertilizer.

AbstractThe rapid shrinkage and salinization of the Aral Sea over the last few decades has precipitated an environmental disaster, with widespread implications for people whose livelihoods depend on it. Although debated extensively, few viable strategies have yet been identified for reviving the Aral Sea. Here, we propose a hydro‐eco‐social framework to develop a viable, sustainable solution and explore its feasibility to resolve the Aral Sea problem. Based on eco‐environmental indicators, we contend that it is feasible to raise the Aral Sea by 40 m above the Baltic Sea level, while maintaining salinity levels tolerable for aquatic organisms, simultaneously reducing sandstorm risk by 58%. Basin‐wide water balance under climate change scenarios shows that this level can be supported through management interventions that reduce water usage by 22.0–23.2 km3/year and ensure sufficient recharge into the lake, without compromising socio‐economic opportunities. To implement this solution, we propose establishing a socio‐ecologically aligned water governance network for basin‐scale water management that has potential application for other, similarly declining, major lake systems.

The global crisis in antimicrobial resistance continues to grow. Estimating the risks of antibiotic resistance transmission across habitats is hindered by the lack of data on mobility and habitat-specificity. Metagenomic samples of 6092 are analyzed to delineate the unique core resistomes from human feces and seven other habitats. This is found that most resistance genes (≈85%) are transmitted between external habitats and human feces. This suggests that human feces are broadly representative of the global resistome and are potentially a hub for accumulating and disseminating resistance genes. The analysis found that resistance genes with ancient horizontal gene transfer (HGT) events have a higher efficiency of transfer across habitats, suggesting that HGT may be the main driver for forming unique but partly shared resistomes in all habitats. Importantly, the human fecal resistome is historically different and influenced by HGT and age. The most important routes of cross-transmission of resistance are from the atmosphere, buildings, and animals to humans. These habitats should receive more attention for future prevention of antimicrobial resistance. The study will disentangle transmission routes of resistance genes between humans and other habitats in a One Health framework and can identify strategies for controlling the ongoing dissemination and antibiotic resistance.

AbstractConverting degraded croplands into perennials has been proposed as an effective method of soil N sequestration, however, the dynamics of deep soil N (>100 cm) following cropland conversion are not well understood. In this study, we synthesized 3049 observations to detect the changes in deep soil N content following cropland conversion on the arid and semiarid Loess Plateau. Our results showed that converting croplands into perennials significantly increased the soil N content by an average of 57.4%, 23.1%, and 29.5% in the surface (0–20 cm), subsurface (20–100 cm), and deep (100–200 cm) layers, respectively. The extent of the increase was influenced significantly by the land‐use conversion types and tree species. Specifically, the conversion of croplands into deep‐rooted forests or shrubs, particularly Robinia pseudoacacia and Caragana microphylla, exhibited higher advantages in deep soil N sequestration. Moreover, deep soil N sequestration increased significantly with time since cropland conversion (p < 0.001), and the rates in deep soils were approximately 26.1% and 66.7% of that in 0–20 and 20–100 cm soils, respectively. In the long term, converting croplands into forests and shrubs showed higher potential for deep soil N sequestration. Linear regression analysis showed that the changes of deep soil N sequestration were influenced significantly by initial soil N content (p < 0.001) and humidity index (p < 0.001), with the slopes in >100 cm layers being 2 to 3 times than that in the top meter, indicating higher sensitivity in deep soils. Overall, this study provides evidence that converting degraded croplands into perennials may contribute to deep soil N accumulation in N‐limited regions, which could potentially alleviate N limitation and sustain long‐term ecosystem carbon sequestration.

AbstractAimContinental comparisons of migration strategies within and between populations of single species are rare but can be insightful to understand key environmental factors shaping differences in migration systems. We investigated differences in stopover networks and migration strategies between three separate Eurasia Greater White‐fronted Geese (GWFG) Anser albifrons populations to better understand how each overcomes the different topographic challenges faced along their migration routes during spring and autumn.LocationEurasia.TaxonBirds.MethodsUsing 106 (autumn) and 65 (spring) tracks from tagged GWFG from three Eurasian populations (Baltic‐North Sea [BNS] in the west; East Asia Continental [EAC] and West Pacific [WP] in the east), we generated stopover networks, calculated network metrics, quantified migration parameters and compared variation between populations and seasons.ResultsBNS showed largest network size, shortest average geodesic distance in both seasons, shortest migration distances, most stopover sites, longest stopover duration and shortest step length. EAC showed longest migration distance and second maximal flight length (>1600 km). WP showed shortest migration durations and longest maximal flight length (>2500 km). Summering ground arrival dates did not differ between populations. Autumn migration duration was shorter and migration speed faster than in spring in all populations.Main ConclusionsWe infer lack of obvious ecological barriers to BNS geese shapes their frequent stopovers of short duration. In contrast, EAC geese face two major ecological barriers (3100 km boreal forest, high mountains, dense human settlement and ocean) and WP geese must pass c. 2400 km of forest, mountains and ocean along their migration corridors, necessitating longer staging and migration segments of greater duration. We conclude that, despite almost identical body plan, all populations respond to radically different topographic challenges, adapting to meet these using different movement strategies, balancing migration schedule and fat accumulation patterns with availability and quality of stopovers.

Global warming has significantly affected terrestrial ecosystems. Biomass and C:N:P stoichiometry of plants and soil is crucial for enhancing plant productivity, improving human nutrition, and regulating biogeochemical cycles. However, the effect of warming on the biomass and C:N:P stoichiometry of different components (plant, leaf, stem, root, litter, soil, and microbial biomass) in various terrestrial ecosystems remains uncertain. We conducted a comprehensive meta-analysis to investigate the global patterns of biomass and C:N:P stoichiometry responses to warming, as well as interaction relationships based on 1399 paired observations from 105 warming studies. Results indicated that warming had a significant impact on various aspects of plant growth, including an increase in plant biomass (+16.55%), plant C:N ratio (+4.15%), leaf biomass (+16.78%), stem biomass (+23.65%), root biomass (+22.00%), litter C:N ratio (+9.54%) and soil C:N ratio (+5.64%). However, it also decreased stem C:P ratio (-23.34%), root C:P ratio (-12.88%), soil N:P ratio (-14.43%) and soil C:P ratio (-16.33%). The magnitude of warming was the primary drivers of changes of biomass and C:N:P stoichiometry. By establishing the general response curves of changes in biomass and C:N:P ratios with increasing temperature, we demonstrated that warming effect on plant, root, and litter biomass shifted from negative to positive, whereas that on leaf and stem biomass changed from positive to negative as temperature increased. Additionally, the effect of warming on root C:N ratio, root biomass, and microbial biomass N:P ratios shifted from positive to negative, whereas the effects on plant N:P, leaf N:P, leaf C:P, root N:P ratios, and microbial biomass C:N ratio changed from negative to positive with increasing temperature. Our research can help assess plant productivity and optimize ecosystem stoichiometry precisely in the context of global warming.