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Straw return has been widely used to increase SOC storage globally, but such C accrual is frequently constrained by other nutrients which are needed to maintain soil ecological stoichiometry balance. However, the impact of fertilization on SOC stocks under straw return remains unexplored at broad spatial scales. We constructed a national-scale dataset to explore the fertilization effect on SOC stocks (0–20 cm) under straw return and identified the dominant drivers and pathways in upland and paddy systems across China. On average, straw return enhanced SOC stocks and sequestration rate by 1.74 Mg C ha−1 and 0.27 Mg C ha−1 y−1 relative to straw removal (CK). Yet, straw co-applied with nutrient enrichment further increased SOC stock and sequestration rate by 0.81 Mg C ha−1 and 0.12 Mg C ha−1 y−1, compared to straw return only. These results indicated a general nutrient limitation on SOC sequestration under straw return. The fertilization effect on SOC stocks varied greatly across nutrient enrichment types and cropping systems, with greater soil C gain occurring under balanced fertilization (i.e., NPK) and more in uplands than in paddy fields. In the uplands, SOC sequestration with fertilization was positively correlated with increased belowground biomass. In paddy fields, however, improved biomass with fertilization did not translate into increased SOC accumulation, owing to the co-limitations of soil acidification and initial SOC. We further clarified the differential pathways by which chemical fertilization altered SOC stocks, i.e., productivity pathway in uplands but decomposition pathway in paddy fields. These mechanistic insights on the fertilization control over SOC can help us optimize the context-specific integrated straw and fertilization management strategies for greater SOC sequestration, and also inform the development of soil C projections by incorporating fertilization management into biogeochemical models in agroecosystems. [Display omitted] • Nutrient limitation of SOC stocks under straw return was assessed across China. • Balanced fertilization promoted SOC sequestration under straw return. • SOC gain due to fertilization was much higher in uplands than in paddy fields. • Improved productivity with fertilization did not translate into increased SOC in paddies. • Fertilization modified SOC stocks via differential pathways across cropping systems. [ABSTRACT FROM AUTHOR]

3 Results 3.1 Characteristics of soil total P concentration across the world Our soil total P concentration database included 5275 measurements from 1894 geographically distinct sites and covered 6 continents, all major biomes, and all 12 USDA soil orders in terrestrial ecosystems (Fig. Besides soil total P concentration and site coordinates, we also included climate variables (i.e., MAT and MAP), vegetation type, and soil physiochemical properties (e.g., SOC, soil clay and sand contents, soil pH) in our database whenever available. Soil chronosequences provide a unique opportunity to isolate the effect of soil age from other soil-forming factors on soil P dynamics and have shown that soil age negatively impacts soil total P concentration (Wardle et al., 2004; Delgado-Baquerizo et al., 2020; Vitousek et al., 2010; Walker and Syers, 1976). In terrestrial ecosystems, to a depth of 1 m from the land surface, most of the P is found in the soil (Zhang et al., 2021). [Extracted from the article]

Aim: The carbon sink in tropical forests is a highly uncertain component of the global carbon budget. An understanding of the processes controlling this sink requires better quantification of carbon allocation, stocks and turnover times. Location: Tropical forests. Time period: 2010–2017. Major taxa studied: Tropical forest ecosystem. Methods: We develop a novel data assimilation system using satellite‐based annual above‐ground biomass derived from L‐band vegetation optical depth with 25 km × 25 km grid spacing, together with leaf area, to constrain the 25 km × 25 km carbon allocation patterns of net primary productivity (NPP) into the wood, leaf and root pools, and their turnover times. Our average data‐driven estimates of these variables are broadly consistent with independent ground‐based estimates of NPP allocation and wood turnover from forest inventory plots. Results: In tropical forest, on average, the NPP allocation into wood (0.30 ± 0.04) is significantly higher than that into leaves (0.24 ± 0.07). From the wet to dry tropics, forest NPP allocation into both wood and leaves declines slightly. The turnover times of forest leaf pools exhibit little spatial variation, whereas the turnover times of wood pools in Africa (median and interquartile range: 50.1‐4.0+5.5 years) are slightly longer than those in South America (48.2‐3.3+4.0 years) and Southeast Asia (48.3‐3.1+5.4 years). Our datasets reveal emergent trade‐offs across climatic and vegetation gradients between growth and life span/turnover for both wood and leaves. The spatial gradients of NPP allocation to wood/leaves are associated with canopy height, adjusted by climate condition and nutrient acquisition. The spatial gradients of wood and leaf turnover times are influenced mainly by climate and leaf characteristics. Main conclusions: Our data‐driven estimates of carbon allocation and turnover times provide a basis for more detailed exploration of these mechanisms in field studies. This highlights that improved model representation of carbon allocation and turnover is necessary for more accurate prediction of future carbon dynamics. [ABSTRACT FROM AUTHOR]

Summary: Nocturnal transpiration is widely observed across species and biomes, and may significantly impact global water, carbon, and energy budgets. However, it remains elusive why plants lose water at night and how to model it at large scales.We hypothesized that plants optimize nighttime leaf diffusive conductance (gwn) to balance potential daytime photosynthetic benefits and nocturnal transpiration benefits. We quantified nighttime benefits from respiratory reductions due to evaporative leaf cooling. We described nighttime costs in terms of a reduced carbon gain during the day because of water use at night. We measured nighttime stomatal responses and tested our model with water birch (Betula occidentalis) saplings grown in a glasshouse.The gwn of water birch decreased with drier soil, higher atmospheric CO2, wetter air, lower leaf temperature, and lower leaf respiration rate. Our model predicted all these responses correctly, except for the response of gwn to air humidity. Our results also suggested that the slow decrease in gwn after sunset could be associated with decreasing leaf respiration.The optimality‐based nocturnal transpiration model smoothly integrates with daytime stomatal optimization approaches, and thus has the potential to quantitatively predict nocturnal transpiration across space and time. [ABSTRACT FROM AUTHOR]

In summer 2018, Europe experienced a record drought, but it remains unknown how the drought affected ecosystem carbon dynamics. Using observations from 34 eddy covariance sites in different biomes across Europe, we studied the sensitivity of gross primary productivity (GPP) to environmental drivers during the summer drought of 2018 versus the reference summer of 2016. We found a greater drought-induced decline of summer GPP in grasslands (−38%) than in forests (−10%), which coincided with reduced evapotranspiration and soil water content (SWC). As compared to the 'normal year' of 2016, GPP in different ecosystems exhibited more negative sensitivity to summer air temperature (Ta) but stronger positive sensitivity to SWC during summer drought in 2018, that is, a stronger reduction of GPP with soil moisture deficit. We found larger negative effects of Ta and vapour pressure deficit (VPD) but a lower positive effect of photosynthetic photon flux density on GPP in 2018 compared to 2016, which contributed to reduced summer GPP in 2018. Our results demonstrate that high temperature-induced increases in VPD and decreases in SWC aggravated drought impacts on GPP. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'. [ABSTRACT FROM AUTHOR]

• Land degradation can be reversed by desert-oasis protection systems. • Protection increased plant cover, soil nutrients, and diminished wind erosion. • Soil salinity, sodicity, and desiccation increased in well protected plantations. • Protection benefit should be weighed against unintended environmental consequences. Oasis-protection systems are created globally to reverse land degradation in drylands and improve ecosystem condition. This study assessed the effects of a 40-year oasis-protection system on soil physicochemical and plant community properties along a gradient from prohibited grazing to fenced shrublands, to shrub- and tree plantation belts in arid northwestern China. We found that compared with shifting dunes in unprotected desert settings, the wind velocity and sand transportation rate decreased by 75 and 98% when spring storms passed through the most protected shrub- and tree- plantations in the oasis-protection system, respectively. The fraction of silt and clay content, and soil carbon, total nitrogen, and total phosphorus significantly increased along the protection gradient, and reached their highest levels at the most protected belts. Meanwhile, an annual herbaceous plant community developed, and the densities, covers, and biomasses of herbaceous plant species increased with soil nutrients along the gradient. However, a significant increase in soil salinity, sodicity, and desiccation occurred at the shrub- and tree plantation belts, and shrub and tree species introduced in the plantations failed to regenerate after 40 years. Our results demonstrate that the positive effects of oasis-protection systems need to be weighed against the long-term negative consequences of soil salt accumulation and desiccation that can occur in frequently used shrub- and tree plantations, which limits future plant regeneration and ecosystem recovery. [ABSTRACT FROM AUTHOR]

Combating climate change requires unified action across all sectors of society. However, this collective action is precluded by the ‘consensus gap’ between scientific knowledge and public opinion. Here, we test the extent to which the iconic cities around the world are likely to shift in response to climate change. By analyzing city pairs for 520 major cities of the world, we test if their climate in 2050 will resemble more closely to their own current climate conditions or to the current conditions of other cities in different bioclimatic regions. Even under an optimistic climate scenario (RCP 4.5), we found that 77% of future cities are very likely to experience a climate that is closer to that of another existing city than to its own current climate. In addition, 22% of cities will experience climate conditions that are not currently experienced by any existing major cities. As a general trend, we found that all the cities tend to shift towards the sub-tropics, with cities from the Northern hemisphere shifting to warmer conditions, on average ~1000 km south (velocity ~20 km.year-1), and cities from the tropics shifting to drier conditions. We notably predict that Madrid’s climate in 2050 will resemble Marrakech’s climate today, Stockholm will resemble Budapest, London to Barcelona, Moscow to Sofia, Seattle to San Francisco, Tokyo to Changsha. Our approach illustrates how complex climate data can be packaged to provide tangible information. The global assessment of city analogues can facilitate the understanding of climate change at a global level but also help land managers and city planners to visualize the climate futures of their respective cities, which can facilitate effective decision-making in response to on-going climate change. [ABSTRACT FROM AUTHOR]

Predicting hydroclimatic changes on the Tibetan Plateau (TP) is crucial for managing water and ecosystems for the well-being of millions of people. Our understanding of the synoptic conditions on the TP is, however, still limited due to the paucity of meteorological measurements and proxy-based, high-resolution climate reconstructions. Here, we use state-of-the-art dendroclimatological techniques to investigate the paleoclimatic potential of drought-sensitive Picea likiangensis var. balfouriana forests between 4000 and 4500 m asl on the southeastern TP (SETP). The newly developed tree-ring width chronology correlates significantly with yearly changes in regional relative air humidity (RH) (r = 0.85, P < 0.001, 1978–2011). A new 407-year-long reconstruction of RH over the hydrological year from previous year August to July of the year of ring formation shows that, despite the generally humid conditions, four of the ten driest years are observed in the twentieth century with 1983 having been the driest. On the other hand, seven out of the ten most humid years were found in the eighteenth century. Our reconstruction reveals that the Pacific Decadal Oscillation (PDO) is the dominant climate driver at multi-decadal scales, but the relationships are not stable over time, with unknown underlying mechanisms. Although our study demonstrates the importance of the PDO for hydroclimate projections on the TP, caution is advised when considering only its most recent fluctuations. [ABSTRACT FROM AUTHOR]

• The uWUE method was cross–compared with three traditional methods. • Daily T partitioned by the uWUE method well agreed with the SW model. • G c had more significant seasonal variations than G s. • The Jarvis model parameterized with G c performed better than those with G s. • The uWUE method can exclude influences of nonstomatal conductances. Canopy conductance (G c) largely regulates carbon/water cycling and land–atmosphere interactions, but quantifying G c using eddy flux data is limited by the difficulty of partitioning plant transpiration (T) and surface evaporation (E). We introduced an underlying water use efficiency (uWUE) method to partition evapotranspiration (ET) in an oasis maize ecosystem, and cross–compared with the Shuttleworth and Wallace (SW) model, the lysimeter and isotope measurements. We then estimated surface conductance (G s) by ET and G c by T partitioned using the uWUE method, followed by a performance evaluation on the Jarvis model parameterized with both G s and G c. The results showed that T/ET estimated by the uWUE method was close to the isotope method in the peak growing season of 2012, it showed similar seasonal variations with the lysimeter/eddy covariance method and the SW model throughout this growing season. Daily T partitioned by the uWUE method was in good agreement with the SW model from 2012 to 2015 (r2 = 0.91). Additionally, G c had more significant seasonal variations than G s. The Jarvis model parameterized with G c exhibited superior performance than those with G s. Our study suggests that the uWUE method can exclude influences of nonstomatal conductances, and will have great potential to provide more reasonable parameterization for simulation of plant stomata. [ABSTRACT FROM AUTHOR]

Highlights • HBA polymer was first-time introduced for accurate detection of VOSCs in SAW sensor. • The as-prepared sensor exhibits excellent sensitivity (LOD ranging 0.035–0.11 mg/m3). • This sensor also has high selectivity (2.23–49.6 times higher response toward VOSCs). • The sensing mechanism was due to hydrogen bonding between HBA and VOSCs. • DFT was first-time employed to calculate the binding energy of HBA-VOSC systems. Abstract Volatile organic sulfur compounds (VOSCs) pose serious threats to environment and human health, while detection techniques of VOSCs are expensive and complex. Here, this paper first-time reported a hydrogen-bond acidic (HBA) polymer-based surface acoustic wave (SAW) chemical sensor for the detection of four VOSCs (methyl mercaptan, dimethyl sulfide, dimethyl disulfide, and carbon disulfide). The results show that this sensor exhibited both excellent sensitivity (limit of detections ranging from 0.035 to 0.11 mg/m3) with fast response and recovery and high selectivity (2.23–49.6 times higher response than interference vapors) toward VOSCs at room temperature. The good performance is attributed to the hydrogen bonding between the sulfur atom of VOSCs and hydrogen atom of hexafluoroisopropanol (HFIP) groups in polymer chain. Fourier-transform infrared spectroscopy (FTIR) spectrum and first principle calculations were performed to further support this proposed mechanism. [ABSTRACT FROM AUTHOR]

The brushless doubly-fed machine (BDFM) without a brush and slip ring has some advantages of high operation reliability and less maintenance cost, which is very suitable for the ship shaft power generation. In this application, the BDFM mainly works on the stand-alone state, in which the power winding (PW) voltage should be controlled directly. The unbalanced load is a typical working state, which mostly results in the unbalance of PW voltage and affects the normal operation of loads severely. The sensorless control strategy can enhance the operation safety under extreme environment and cut down the cost effectively, which is highly desired to be applied in the BDFM-based ship shaft power generation. In this paper, an improved sensorless phase control strategy is proposed, which can work effectively under the unbalanced load condition. First, the sensorless operation is achieved by controlling the $q$ -component of PW voltage, which can realize the phase control simultaneously. Then, the unbalanced compensation is designed in details. Finally, both simulation and experiments have demonstrated that, by the proposed method, the PW voltage phase can be controlled precisely and the voltage unbalance factor is lower than the permissible level. [ABSTRACT FROM AUTHOR]

This paper proposes a novel control method for an asymmetrical-cascaded-multilevel-converter-based hybrid energy storage system (HESS), which includes one battery and several electrical double-layer capacitors (EDLCs). Traditionally, it is challenging to control the power distribution between different cascaded H-bridges by using different energy storage components as dc sources. In this paper, a feedforward space-vector-modulation (FFSVM) technique is used to distribute the active power between the battery and EDLCs. With the proposed voltage feedforward mechanism, the HESS can flexibly operate in the normal operation mode, the high-power output mode, and the reverse power absorption mode. The principle and effectiveness of the improved FFSVM technique are analyzed. Meanwhile, the state-of-charge-balancing mechanisms are introduced. The simulation results obtained in MATLAB/Simulink as well as the experimental results of a hybrid energy storage test bed based on the proposed system are presented to verify its performance. [ABSTRACT FROM PUBLISHER]

When restoring dryland ecosystems, growing biological soil crust (biocrust) may greatly change the redistribution of rainfall in layered soils. However, ecohydrological modelling studies generally ignore biocrust and thus, the ecohydrological effects of biocrust on restorations remain largely unexplored. Using a long-term restoration case (located in the southeast edge of the Tengger Desert, northern China), we developed an ecohydrological model with explicit consideration of the infiltration in three layered soils (biocrust, shallow and deep sand layers) to investigate influences of biocrust on restoration dynamics in drylands. The proportion of infiltration that reaches ‘annual grass’ (including biocrust and shallow sand layers, 0–30 cm) and ‘shrub’ layers (30–150 cm) with biocrust significantly increased and decreased relative to the values without biocrust, respectively. Meanwhile, biocrust significantly decreased soil water content in deep sand layer, but not in shallow sand layer. As more water was used by transpiration than evaporation, the ecosystem with biocrust reached a final grass-dominated state (high grass cover of 40%, low shrub cover of 4%) rather than a shrub-dominated state (grass cover of 3%, shrub cover of 20%). This study suggests that we need to account for the roles of biocrust on rainfall infiltration to better understand vegetation and restoration dynamics in dryland ecosystems. [ABSTRACT FROM AUTHOR]

Siberia has experienced a pronounced warming over the past several decades, which has induced an increase in the extent of evergreen conifer forest. However, the potential slowing of the trend of increasing surface air temperature (SAT) has produced intense debate since the late 1990s. During this warming hiatus, the Siberian region experienced a significant cooling during the winter season around 10 times that of the Northern Hemisphere (NH) as a whole. This potentially stresses evergreen conifer forests because cooler winters can cause cold-temperature damage and, hence, increase the mortality of young evergreen conifer forests. In this study, the response of Siberian forest composition during the warming hiatus was investigated using satellite observations coupled with model simulations. Observations indicated that from 2001 to 2012, the apparent area of evergreen conifer forest has increased by 10%, while that of the deciduous conifer forest has decreased by 40%. The transition from deciduous to evergreen conifer forest usually occurs through mixed forest or woody savannas as a buffer. To verify the response of evergreen conifer forest, model experiments were performed using an individual-based forest model. Hysteresis of forest change seen in the model simulations indicates that changes in forest composition dynamics under temperature oscillations induced by internal climate variability may not reverse this composition change. As a result, the evergreen conifer forest expansion under climate warming is expected to be a continuing process despite the occurrence of a warming hiatus, exerting far-reaching implications for climate-change-induced albedo shifts in the Siberian forest. [ABSTRACT FROM AUTHOR]

Biochar amendment can alter native soil organic carbon (SOC) mineralization via the priming effect (PE); however, its direction, intensity, and controls over a broad geographic scale are not clear, undermining the predictions of SOC dynamics as impacted by biochar inputs. Here, we synthesized 5,720 measurements of CO 2 effluxes from 329 soil samples with and without 13C/14C labeled-biochar additions to quantify the spatial patterns and temporal dynamics of the PE and assess the underlying environmental drivers. Across all data, biochar amendment has led to a slight but significant positive PE (i.e., 56 mg C kg−1 soil), with stronger PEs in natural ecosystems than in agricultural soils. Negative PE occurred in the short term (i.e., <9 days after biochar addition) and subsequently shifted to a strong positive PE (i.e., 364–966 days) and remained in an insignificant PE thereafter (i.e., >1450 days). Notably, soils from rainfed croplands had the lowest negative PE (−28.76 mg C kg−1 soil). Grass-derived biochar produced at a low pyrolysis temperature (i.e., 300–400 °C) induced the strongest positive PE (244 mg C kg−1 soil). The results of our structural equation model indicated that biochar pyrolysis temperature and soil C:N ratio had the largest negative and direct association with biochar-induced PE, whereas incubation temperature and microbial biomass C exerted the greatest positive and direct effects on the PE. Variance partitioning analyses further revealed that both biochar and soil properties together accounted for 73% of the explained variance in biochar-induced PE. Overall, these results add to our understanding of biochar-induced SOC priming as impacted by different land-use types, soils, and biochar properties. The amendment of wood-derived biochars produced at high pyrolysis temperatures (>500 °C) to rainfed croplands could serve as a promising strategy to achieve maximum soil C sequestration. [Display omitted] • Biochar amendment led to a significant positive priming effect (PE). • Soils from natural ecosystems exhibited stronger PEs than agricultural soils. • Grass-derived biochar produced higher PEs than wood- and crop-derived biochar. • The PEs decreased as biochar pyrolysis temperature and soil C:N ratio increased. • The PEs increased as incubation temperature and microbial biomass C increased. [ABSTRACT FROM AUTHOR]

Accurate estimation of evapotranspiration (ET) is essential for understanding terrestrial energy, water, and carbon cycles. This study proposes a hybrid model integrating in-situ and remote sensing-derived soil moisture (SM) observations and remote sensing leaf area index (LAI) with the Noah-MP model. The ensemble Kalman filter (EnKF) approach updates the leaf biomass and specific leaf area (SLA) by assimilating the remotely sensed LAI. A machine learning (ML) surrogate model is used to integrate multi-site SM profile observations and remote sensing SM products to estimate the three-layer SM. An iterative coupling of two parts implements the hybrid model: optimization of leaf biomass and SLA by assimilation of LAI in the Noah-MP model and simulation of three-layer SM in the ML surrogate model. The performance of the hybrid model is evaluated in the Heihe River Basin (HRB) in northwest China. The estimated ET from the hybrid model is compared with observations from the large aperture scintillometer (LAS) at the Arou, Daman, and Sidaoqiao sites and up-scaled watershed ET over the HRB. The findings indicate that the hybrid model performs well in vegetated areas but underestimates ET in extreme arid deserts. The three-site unbiased root mean squared errors (ubRMSEs) of ET estimates from the hybrid model are 29.06%, 42.76%, and 50.00% lower than Noah-MP at the Arou, Daman, and Sidaoqiao sites, respectively. The coupling of data assimilation (DA) and ML methods can improve vegetation dynamics and SM transport estimation in the Noah-MP model. The hybrid model can take advantage of DA and ML methods and integrate multi-source observations to improve the accuracy of ET estimation. The results also indicate that the ET predictions are more sensitive to root zone SM (0–40 cm) over croplands, grasslands, and shrublands, while the ET simulations are more affected by deeper rooting depths SM (0–100 cm) and groundwater over forests. • The DA and ML methods are used to construct the hybrid model. • Multi-source SM and remotely sensed LAI are integrated into the hybrid model. • The hybrid model ET estimates are validated with LAS and up-scaled watershed ET. • The hybrid model can improve the management of agricultural water resources. [ABSTRACT FROM AUTHOR]

Quantifying soil P fractions is essential for understanding soil P cycling because these fractions are potential sources of bioavailable P. Here, we investigated whether soil P fractions (i.e., labile inorganic P [P], intermediately available P, organic P, occluded P, and apatite P) differed among three tropical forests at different stages of succession (early, middle, and late) in the Dinghushan Biosphere Reserve (DBR), Southern China. We also determined which soil P fractions was closely related to soil microbial and chemical properties in these forests. Soil microbial biomass and chemical properties (except pH, exchangeable Ca, and Mn) were higher in the late successional forest than those in the other two forests. We found that soil organic and occluded P were the dominant fraction in all three forests and together accounted for 78.9, 84.2, and 78.6 % of total P in the early, middle, and late successional forests, respectively. Soil P fractions and acid phosphomonoesterase activity differed significantly among forest successional stages; intermediately available P and organic P (potential sources of labile P) were highest in the late successional forest, occluded P was highest in the middle successional forest, and acid phosphomonoesterase activity significantly increased in middle and late successional forest. Soil labile P fraction and its potential sources (i.e., intermediately available P and soil organic P) were both positively correlated with soil microbial and chemical properties, suggesting that these properties may play critical roles in maintaining high levels of available or potentially available P fractions during this forest succession. Overall, our study indicates that succession in tropical forest ecosystems may not always lead to lower soil P availability. [ABSTRACT FROM AUTHOR]

• The PHM captures the observed Ψ l , sap-flow and ecosystem ET. • Hydraulic sensitivities generally reduce as the water stresses intensify. • Ecosystem water flux and mortality risk are not always coupled. • Hydraulic traits control the stress resistance of desert riparian ecosystems. • Different water stresses have coupled impact on ET and mortality risk. Plant response to soil and atmospheric water stresses is the dominant control of Dryland ecosystem functions, affecting water resources, ecosystem stability and biodiversity. The link between water stresses and plant water status is regulated by plant hydraulics, of which the corresponding impact on plant water use and the susceptibility of Dryland ecosystems remains under-explored. We used a plant hydraulic model to describe hydraulic states and water flux of two species (Populus euphratica and Tamarix ramosissima) in desert riparian ecosystems. We optimized hydraulic parameters and tested the model using observed physiological states and ecosystem water flux. The optimized model was used to evaluate plant hydraulic sensitivity, tree mortality risk, and evapotranspiration under a wide range of water stress scenarios. The model captures the observed leaf water potential, sap-flow and ecosystem evapotranspiration. Our scenario analysis demonstrates that hydraulic sensitivities generally reduce as the water stresses intensify. The results highlight a strong coupled impact of the co-occurrence of soil and atmospheric water stresses on restricting ecosystem water flux and intensifying mortality risk. The assessment of multiple aspects of eco-physiological functions and the stress scenario analysis of desert riparian ecosystems will contribute to a better prediction of ecosystem functions and facilitate resource management under future climate. [ABSTRACT FROM AUTHOR]

Altered drying-rewetting patterns due to climate change may affect soil nitrogen (N) and phosphorus (P) cycling in terrestrial ecosystems. The responses of soil N and P cycling to drying and rewetting cycles can vary with drying-rewetting patterns, experimental methods, ecosystems, and soil types, thus making a synthesis of these studies necessary for understanding mechanisms and predicting future responses to climate change. Here, we compiled data of 1882 observations from 79 studies for a meta-analysis of the responses of soil N and P pools and fluxes to drying and rewetting and how these responses are modified by experimental conditions. Results showed that 1) experimental drying increased NH 4 +, extractable organic nitrogen (EON), and available P in the soil significantly by 22, 27, and 72%, respectively. In contrast, soil NO 3 −, enzymatic activities, microbial biomass, net nitrification, and N 2 O emissions significantly decreased by 37, 13–21, 21–28, 39, and 93%, respectively. 2) Upon rewetting of dried soil, soil EON, extractable organic phosphorus (EOP), net N mineralization, nitrification, phosphatase activity, dissolved organic N leaching, dissolved inorganic P leaching, and N 2 O emissions significantly increased by 59, 27, 19, 15, 12, 60, 116, and 218%, respectively, while soil NO 3 − and NO 3 − leaching significantly decreased by 9 and 74%, respectively. Soil microbial N and P as well as enzymatic activities recovered from drought during the rewetting phase. The mean effect sizes of drying and rewetting generally increased with drying intensity, which was probably also the main reason for greater effect sizes observed in laboratory than in field experiments. Our meta-analysis showed stronger positive responses of available P to drying and rewetting than mineral N, which agreed with greater effect sizes on P than on N leaching. This suggests that drying and rewetting induce an imbalance between N and P, which was more pronounced in soils from forests than from agricultural systems. Overall, these results imply that the expected increase in the frequency and intensity of droughts potentially decouples the cycling of P and N, with consequences for nutrient leaching and the supply of plants and microorganisms with these nutrients. • We compiled data of 1882 observations and conducted a meta-analysis. • Drying and rewetting significantly affected soil N and P pools and fluxes. • Soil microorganisms could recover from drought on rewetting. • There were higher effect sizes of N and P in laboratory than in field. • The responses of soil N and P also depended on soil and land use types. [ABSTRACT FROM AUTHOR]