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A novel multi-combined-step-size normalized subband adaptive filtering algorithm is proposed. Different from the traditional combined-step-size method, by employing a variable mixing parameter on each subband, our designed algorithm is able to combine a large step size with a small one more effectively for each subband. The subband mixing parameters are derived from the variance of the noise-free a priori subband error signals. In this design, a noniterative shrinkage strategy is also utilized to estimate the noise-free a priori subband error signals. Moreover, the mean-square and steady-state performances of the proposed algorithm are studied. Simulation results illustrate that the proposed algorithm outperforms other algorithms mentioned in this paper in terms of tracking capability, convergence speed and steady-state error. [ABSTRACT FROM AUTHOR]

Taking the Giant Panda National Park as an example, this paper uses factor analysis to measure residents' financial awareness and mediating effect models to investigate the influence paths of community governance, financial awareness, and residents' willingness to participate in the construction and development of national parks. Finally, it suggests potential solutions for national park development and biodiversity conservation. The results indicated that financial awareness and community governance levels had a positive effect on residents' willingness to participate, and satisfaction with community governance played a significant partially mediating role in their financial awareness, which in turn influenced their level of willingness. [ABSTRACT FROM AUTHOR]

The rationally structural engineering is an efficient strategy to improve the comprehensive performance of potassium‐ion storage anode materials. In this paper, a hybrid with hollow FeS2 nanoparticles anchored into the 3D carbon skeleton (labeled as H‐FeS2@3DCS) is successfully constructed through two critical steps of in situ chemical deposition and anion‐exchange reaction strategies. In the former, the water‐soluble Na2CO3 crystals are used as hard templates for the preparation of 3DCS, while Fe3+‐containing aqueous solutions are utilized to remove the Na2CO3 templates. Interestingly, the intense collision between Fe3+ and CO32‐ in aqueous solution produces nanoscale Fe(OH)3 colloidal particles, which are firmly anchored into the pores of the carbon skeleton to form a "lotus‐seed"‐like nanostructure. In the latter case, a central void space is created inside the FeS2 nanoparticles due to the different diffusion rates of S‐anions and Fe‐cations during the subsequent sulfidation process. Thanks to this unique composition model, the H‐FeS2@3DCS hybrid not only alleviates the volume expansion efficiently by rationally hollow structure design, but also provides spacious "roads" (3D carbon skeleton) and "houses" (hollow FeS2 nanoparticles) for fast K‐ion transition and storage. As the anode of PIBs and PIHCs, the resultant H‐FeS2@3DCS electrode delivers an obviously enhanced K‐ions storage performance over state‐of‐the‐art. [ABSTRACT FROM AUTHOR]

We study a parallel multi-access edge computing (MEC) system in this work and investigate its energy-efficient resources management. Particularly, the MEC system consists of an edge node and a number of mobile users, where each user has an inelastic computing task with nonnegligible duration of task execution and nonnegligible size of task result. In addition, the MEC system operates in orthogonal frequency division multiple access (OFDMA) wireless networks and can support the transmission as well as the execution of different tasks in parallel. On this basis, we build a nonconvex mixed-integer nonlinear programming (MINLP) problem aiming to minimize the energy consumed by the system. By using the McCormick method and exploring the problem's structural properties, we first equivalently transform it to a manageable convex MINLP problem, and then devise two low-complexity suboptimal algorithms. Finally, numerical results are presented to show the effectiveness of our proposed algorithms. [ABSTRACT FROM AUTHOR]

AbstractIn the post-pandemic era, tourists are increasingly interested in sustainable consumption, particularly focusing on green hotels. Given the ongoing endemic nature of COVID-19, our research explores the effects of tourists’ residential locations, specifically pandemic-affected areas, on their intention to choose green hotels. Drawing on the Protection Motivation Theory, we discuss how and why residential location influences risk perception, which in turn motivates tourists to contribute to environmental protection by opting for green hotels. Results from five experiments suggest that the influence of pandemic areas on green hotel consumption can fluctuate over time. During the initial outbreak, a positive correlation emerges between tourists’ risk perception and their distance from the pandemic’s epicenter. Those residing in marginal areas show greater threat appraisal and stronger intentions toward choosing green hotels than tourists in central areas. However, this relationship is found to reverse during the mitigation and post-pandemic phases. Furthermore, our research reveals that hotels can significantly sway tourists toward green consumption through the strategic use of hope or fear appeals in advertising. These findings enrich the literature on pandemic-related influences on green consumption and offer practical insights for hotel managers and policymakers seeking to promote sustainable travel more effectively in the post-pandemic era. [ABSTRACT FROM AUTHOR]

Template‐assistant design and fabrication of porous carbon electrode materials has experienced great progress throughout the past decades and yielded lots of successes via various gas or solid state templates. Nevertheless, liquid‐state templates are rather rare in preparing porous carbon materials to date. In this work, melting B2O3 beads are used as both templates and a B dopant, leading to unique B, N co‐doping hierarchically porous carbons containing a "bubble pool"‐like skeleton built of interconnected carbon nanobubbles. Notably, an interesting amending effect of doped B atoms on the N‐doped carbon network can be identified for the first time, which creates a "paddy field"‐like hybrid microstructure with the co‐existence of sp2 short‐range order and sp3 defective areas, leading to an ideal model of carbon materials with both good conductivity and high capacity. Together with the rich ion diffusing pathways and the structural integrity of the "bubble pool"‐like skeleton, the resultant electrode delivers a comprehensive K‐ion storage performance. Therefore, the findings demonstrate the unique pore‐making merits of liquid state templates, which may open the door for exploring porous carbons with more innovations of microstructures and functionalities for applications in energy storage and other fields. [ABSTRACT FROM AUTHOR]

Many studies highlight the merits of positive reviews on social networking sites (SNSs), suggesting that consumers tend to consider these to be trustworthy recommendations. This study draws attention to the potential negative effects of luxury hotels' positive reviews on SNSs. We propose that positive reviews may encourage social comparison and trigger feelings of malicious envy, thereby negatively influencing purchase intentions. Results from two experiments show that high similarity between the review writer and readers increases readers' social comparison tendency, which induces malicious envy when the writer is considered undeserving of luxury hotel consumption. This leads to decreased purchase intentions toward the hotel brand mentioned in the review and increased purchase intentions toward competing hotel brands. The findings have implications for buzz marketing strategies seeking to mitigate the risk of eliciting malicious envy on SNSs. [ABSTRACT FROM AUTHOR]

Consumers usually endorse tourism products differently when sharing positive electronic word-of-mouth (eWOM). This research examines the relative persuasiveness of two endorsement styles, that is, explicit endorsement (e.g., "I recommend it") and implicit endorsement (e.g., "I love it"). Drawing on the persuasion knowledge model, we propose that explicit endorsements are less persuasive than implicit endorsements because the former trigger stronger persuasion knowledge. We further argue that source trustworthiness mitigates the persuasion effect difference between the two endorsement styles. This article assesses these hypotheses across different sources (anonymous reviewers, friends, influencers), channels (online community, social commerce platform, social networking app), and products (hotels, restaurants) using secondary data analysis and two experiments. Three studies provide support for our hypotheses. By revealing the relationship between endorsement styles and eWOM persuasiveness, this article provides important implications for implementing effective product endorsement. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC), as a crucial measure of soil quality, is typically low in arid regions due to salinization, which is a global issue. How soil organic carbon changes with salinization is not a simple concept, as high salinity simultaneously affects plant inputs and microbial decomposition, which exert opposite effects on SOC accumulation. Meanwhile, salinization could affect SOC by altering soil Ca2+ (a salt component), which stabilizes organic matter via cation bridging, but this process is often overlooked. Here, we aimed to explore i) how soil organic carbon changes with salinization induced by saline-water irrigation and ii) which process drives soil organic carbon content with salinization, plant inputs, microbial decomposition, or soil Ca2+ level. To this end, we assessed SOC content, plant inputs represented by aboveground biomass, microbial decomposition revealed by extracellular enzyme activity, and soil Ca2+ along a salinity gradient (0.60–31.09 g kg−1) in the Taklamakan Desert. We found that, in contrast to our prediction, SOC in the topsoil (0–20 cm) increased with soil salinity, but it did not change with the aboveground biomass of the dominant species (Haloxylon ammodendron) or the activity of three carbon-cycling relevant enzymes (β-glucosidase, cellulosidase, and N-acetyl-beta-glucosaminidase) along the salinity gradient. Instead, SOC changed positively with soil exchangeable Ca2+, which increased linearly with salinity. These results suggest that soil organic carbon accumulation could be driven by increases in soil exchangeable Ca2+ under salinization in salt-adapted ecosystems. Our study provides empirical evidence for the beneficial impact of soil Ca2+ on organic carbon accumulation in the field under salinization, which is apparent and should not be disregarded. In addition, the management of soil carbon sequestration in salt-affected areas should be taken into account by adjusting the soil exchangeable Ca2+ level. [Display omitted] • Soil organic carbon increased with salinity after 12 years of saline-water irrigation. • Soil organic carbon increased positively with soil exchangeable Ca2+. • Soil exchangeable Ca2+ increased with salinity. • Hydrolytic enzyme activities did not vary significantly with salinity. • Aboveground biomass of Haloxylon ammodendron did not change with salinity. [ABSTRACT FROM AUTHOR]

Soil inorganic carbon (SIC) is of key importance to the global carbon cycle and mitigating climate change. However, decades of agricultural expansion in the drylands have resulted in vast and fragmented agricultural landscapes and have potentially affected SIC. Previous studies investigating the impact of agricultural expansion on SIC have primarily focused on cultivation impacts, while ignoring edge effects from agricultural land boundaries. Here, we combined cultivation impacts with edge effects and fully evaluated the impacts of agricultural expansion on SIC. We conducted spatial statistical and buffer analyses using a SIC distribution map, which was developed using 388 sample points in 0 – 20 cm topsoil over the Sangong River watershed in drylands of China. We found that decades-long agricultural expansion resulted in lower content and higher variability of SIC in topsoil. Specifically, cultivation decreased SIC content by 28.57% (1.64 g kg−1) and increased SIC variability by 95.71% (0.67 g kg−1) in agricultural lands. Edge effects altered SIC content by − 1.95–11.51% (−0.11 to 0.54 g kg−1) and increased SIC variability by 39.14% (0.34 g kg−1) at edges. In addition, we found that fewer sampling points in areas with high SIC variability (e.g., agricultural lands and edges) decreased the estimation accuracy. Our study highlights the need for SIC conservation during dryland agricultural expansion. Also, it suggests that as many sampling points as possible should be set in high variability areas, which is especially useful for accurately estimating SIC distribution in drylands. [Display omitted] • Dryland agricultural expansion dramatically increased the length of agricultural land boundary. • Cultivation and edge effects increased the variability of soil inorganic carbon (SIC). • SIC content decreased with cultivation years. • More sampling points in areas of high variability improve estimation accuracy of SIC distribution. [ABSTRACT FROM AUTHOR]

With the rapid development of artificial intelligence, information system, and mobile technologies, some companies (e.g. airlines) consider fully replacing service employees with self-service technologies (SSTs) to cut down costs and to increase efficiency. However, replacing full services with SSTs sometimes fail to deliver the benefits companies have hoped for: users may feel that they are being forced to use SSTs and show resistance to the new technologies. To investigate why users show resistance, we draw inferences from psychological reactance theory and argue that users may perceive the forced adoption as a threat, which leads to resistance of SSTs. A conceptual model was developed and an empirical study was conducted. The results show that, under a forced situation, users are likely to perceive the forced adoption as a threat to their freedom, causing them to have negative emotions and perceptions towards the SSTs, and, in turn, their adoption intention decreases and switch intention increases. The findings provide insights on why users show resistance to SSTs and highlight the impacts of the motivational state of psychological reactance. [ABSTRACT FROM AUTHOR]

The roles of soil fungal diversity and community composition in regulating soil respiration when above‐ and below‐ground plant carbon (C) inputs are excluded remain unclear. In the present study, we aimed to examine the following. (a) How does the exclusion of above‐ and below‐ground plant C inputs affect soil respiration and soil fungi singly and in combination? (b) Are changes in soil fungal diversity aligned with changes in soil respiration? A field experiment with manipulation of plant C inputs was established in a subtropical forest in southwest China in 2004 with litter removal and tree stem‐girdling to exclude inputs of the above‐ and below‐ground plant C, respectively. In 2009, we measured the rates of soil respiration with an infrared gas analyser and soil fungal community structure using Illumina sequencing. We found that the rates of soil respiration were reduced significantly by litter removal and girdling, by similar magnitudes. However, they were not decreased further by the combination of these two treatments compared to either treatment alone. In contrast, litter removal increased the diversity of soil fungal communities, whereas girdling decreased the abundance of symbiotrophic fungi but increased the abundance of saptrotrophic and pathotrophic fungi. These changes in soil fungal community might initiate CO2 emission from soil C decomposition, offsetting further decline in soil respiration when plant C inputs are excluded. These results revealed that the exclusion of the above‐ and below‐ground plant C inputs led to contrasting soil fungal communities but similar soil function. Our findings suggest that both above‐ and below‐ground plant C are important in regulating soil respiration in subtropical forests, by limiting substrates for soil fungal growth and altering the diversity and composition of the soil fungal community. Highlights: Litter removal and girdling decreased soil respiration by similar magnitudesThe combination of litter removal and girdling did not further decrease soil respirationLitter removal significantly increased species richness of soil fungal communitiesGirdling changed the abundance of functional guilds of soil fungal communities [ABSTRACT FROM AUTHOR]

Aims: This study aimed to evaluate the associations between types of night shift work and different indices of obesity using the baseline information from a prospective cohort study of night shift workers in China. Methods: A total of 3,871 workers from five companies were recruited from the baseline survey. A structured self-administered questionnaire was employed to collect the participants’ demographic information, lifetime working history, and lifestyle habits. Participants were grouped into rotating, permanent and irregular night shift work groups. Anthropometric parameters were assessed by healthcare professionals. Multiple logistic regression models were used to evaluate the associations between night shift work and different indices of obesity. Results: Night shift workers had increased risk of overweight and obesity, and odds ratios (ORs) were 1.17 (95% CI, 0.97–1.41) and 1.27 (95% CI, 0.74–2.18), respectively. Abdominal obesity had a significant but marginal association with night shift work (OR = 1.20, 95% CI, 1.01–1.43). A positive gradient between the number of years of night shift work and overweight or abdominal obesity was observed. Permanent night shift work showed the highest odds of being overweight (OR = 3.94, 95% CI, 1.40–11.03) and having increased abdominal obesity (OR = 3.34, 95% CI, 1.19–9.37). Irregular night shift work was also significantly associated with overweight (OR = 1.56, 95% CI, 1.13–2.14), but its association with abdominal obesity was borderline (OR = 1.26, 95% CI, 0.94–1.69). By contrast, the association between rotating night shift work and these parameters was not significant. Conclusion: Permanent and irregular night shift work were more likely to be associated with overweight or abdominal obesity than rotating night shift work. These associations need to be verified in prospective cohort studies. [ABSTRACT FROM AUTHOR]

Quantifying soil organic carbon ( SOC) decomposition under warming is critical to predict carbon-climate feedbacks. According to the substrate regulating principle, SOC decomposition would decrease as labile SOC declines under field warming, but observations of SOC decomposition under warming do not always support this prediction. This discrepancy could result from varying changes in SOC components and soil microbial communities under warming. This study aimed to determine the decomposition of SOC components with different turnover times after subjected to long-term field warming and/or root exclusion to limit C input, and to test whether SOC decomposition is driven by substrate lability under warming. Taking advantage of a 12-year field warming experiment in a prairie, we assessed the decomposition of SOC components by incubating soils from control and warmed plots, with and without root exclusion for 3 years. We assayed SOC decomposition from these incubations by combining inverse modeling and microbial functional genes during decomposition with a metagenomic technique (GeoChip). The decomposition of SOC components with turnover times of years and decades, which contributed to 95% of total cumulative CO2 respiration, was greater in soils from warmed plots. But the decomposition of labile SOC was similar in warmed plots compared to the control. The diversity of C-degradation microbial genes generally declined with time during the incubation in all treatments, suggesting shifts of microbial functional groups as substrate composition was changing. Compared to the control, soils from warmed plots showed significant increase in the signal intensities of microbial genes involved in degrading complex organic compounds, implying enhanced potential abilities of microbial catabolism. These are likely responsible for accelerated decomposition of SOC components with slow turnover rates. Overall, the shifted microbial community induced by long-term warming accelerates the decomposition of SOC components with slow turnover rates and thus amplify the positive feedback to climate change. [ABSTRACT FROM AUTHOR]

Soil organic carbon ( SOC) dynamics are regulated by the complex interplay of climatic, edaphic and biotic conditions. However, the interrelation of SOC and these drivers and their potential connection networks are rarely assessed quantitatively. Using observations of SOC dynamics with detailed soil properties from 90 field trials at 28 sites under different agroecosystems across the Australian cropping regions, we investigated the direct and indirect effects of climate, soil properties, carbon (C) inputs and soil C pools (a total of 17 variables) on SOC change rate ( r C, Mg C ha−1 yr−1). Among these variables, we found that the most influential variables on r C were the average C input amount and annual precipitation, and the total SOC stock at the beginning of the trials. Overall, C inputs (including C input amount and pasture frequency in the crop rotation system) accounted for 27% of the relative influence on r C, followed by climate 25% (including precipitation and temperature), soil C pools 24% (including pool size and composition) and soil properties (such as cation exchange capacity, clay content, bulk density) 24%. Path analysis identified a network of intercorrelations of climate, soil properties, C inputs and soil C pools in determining r C. The direct correlation of r C with climate was significantly weakened if removing the effects of soil properties and C pools, and vice versa. These results reveal the relative importance of climate, soil properties, C inputs and C pools and their complex interconnections in regulating SOC dynamics. Ignorance of the impact of changes in soil properties, C pool composition and C input (quantity and quality) on SOC dynamics is likely one of the main sources of uncertainty in SOC predictions from the process-based SOC models. [ABSTRACT FROM AUTHOR]

This study used a mixed method to investigate the dual effects of the flow experience provided by tourism live streaming (TLS) on tourists' travel intentions and how such effects vary across different types of destinations. The results reveal that, in contrast to managers' predictions, while flow experience from TLS may boost offline travel through inspiration, it can also increase tourists' concern for substitutability and thereby reduce their travel intentions. Live streamers' expertise positively moderates the positive effect of flow experience on inspiration. Furthermore, the negative impacts are more salient in highly reputable cultural destinations and natural destinations with limited reputation. [ABSTRACT FROM AUTHOR]

Improving predictions of soil organic carbon (SOC) dynamics by multi-compartment models requires validation of turnover times of different SOC pools. Techniques such as laboratory incubation and isotope analysis have been adopted to estimate C turnover times, yet no studies have systematically compared these techniques and assessed the uncertainties associated with them. Here, we tested whether C turnover times of soil fractions were biased by methodology, and how this changed across soil particle sizes and ecosystems. We identified 52 studies that quantified C turnover times in different soil particles fractionated either according to aggregate size ( e.g. , macro- versus micro-aggregates) or according to soil texture ( e.g. , sand versus silt versus clay). C turnover times of these soil fractions were estimated by one of three methods: laboratory incubation (16 studies), δ 13 C shift due to C 3 –C 4 vegetation change (25 studies), and 14 C dating (19 studies). All methods showed that C turnover times of soil fractions generally increase with decreasing soil particle size. However, estimates of C turnover times within soil fractions differed significantly among methods, with incubation estimating the shortest turnover times and 14 C the longest. The short C turnover times estimated by incubation are likely due to optimal environmental conditions for microbial decomposition existing in these studies, which is often a poor representation of field conditions. The 13 C method can only be used when documenting a successive C 3 versus C 4 vegetation shift. C turnover times estimated by 14 C were systematically higher than those estimated by 13 C, especially for fine soil fractions ( i.e. , silt and clay). Overall, our findings highlight methodological uncertainties in estimating C turnover times of soil fractions, and correction factors should be explored to account for methodological bias when C turnover times estimated from different methods are used to parameterize soil C models. [ABSTRACT FROM AUTHOR]

Mineral-associated organic carbon (MOC), that is stabilized by fine soil particles (i.e., silt plus clay, <53 μm), is important for soil organic carbon (SOC) persistence and sequestration, due to its large contribution to total SOC (TSOC) and long turnover time. Our objectives were to investigate how climate, soil type, soil texture, and agricultural managements affect MOC contributions to TSOC in China. We created a dataset from 103 published papers, including 1106 data points pairing MOC and TSOC across three major land use types: cropland, grassland, and forest. Overall, the MOC/TSOC ratio ranged from 0.27 to 0.80 and varied significantly among soil groups in cropland, grassland, and forest. Croplands and forest exhibited significantly higher median MOC/TSOC ratios than in grassland. Moreover, forest and grassland soils in temperate regions had higher MOC/TSOC ratios than in subtropical regions. Furthermore, the MOC/TSOC ratio was much higher in ultisol, compared with the other soil types. Both the MOC content and MOC/TSOC ratio were positively correlated with the amount of fine fraction (silt plus clay) in soil, highlighting the importance of soil texture in stabilizing organic carbon across various climate zones. In cropland, different fertilization practices and land uses (e.g., upland, paddy, and upland-paddy rotation) significantly altered MOC/TSOC ratios, but not in cropping systems (e.g., mono- and double-cropping) characterized by climatic differences. This study demonstrates that the MOC/TSOC ratio is mainly driven by soil texture, soil types, and related climate and land uses, and thus the variations in MOC/TSOC ratios should be taken into account when quantitatively estimating soil C sequestration potential of silt plus clay particles on a large scale. [ABSTRACT FROM AUTHOR]

Organic carbon (C) associated with fine soil particles (<20 μm) is relatively stable and accounts for a large proportion of total soil organic C (SOC). The soil C saturation concept proposes a maximal amount of SOC that can be stabilized in the fine soil fraction, and the soil C saturation deficit (i.e., the difference between current SOC and the maximal amount) is presumed to affect the capacity, magnitude, and rate of SOC storage. In this study, we argue that predictions using current models underestimate maximal organic C stabilization of fine soil particles due to fundamental limitations of using least-squares linear regression. The objective was to improve predictions of maximal organic C stabilization by using two alternative approaches; one mechanistic, based on organic C loadings, and one statistical, based on boundary line analysis. We collected 342 data points on the organic C content of fine soil particles, fine particle mass proportions in bulk soil, dominant soil mineral types, and land use types from 32 studies. Predictions of maximal organic C stabilization using linear regression models are questionable because of the use of data from soils that may not be saturated in SOC and because of the nature of regression itself, resulting in a high proportion of presumed over-saturated samples. Predictions of maximal organic C stabilization using the organic C loading approach fit the data for soils dominated by 2:1 minerals well, but not soils dominated by 1:1 minerals; suggesting that the use of a single value for specific surface area, and therefore a single organic C loading, to represent a large dataset is problematic. In boundary line analysis, only data representing soils having reached the maximal amount (upper tenth percentile) were used. The boundary line analysis estimate of maximal organic C stabilization (78 ± 4 g C kg fraction) was more than double the estimate by the linear regression approach (33 ± 1 g C kg fraction). These results show that linear regression models do not adequately predict maximal organic C stabilization. Soil properties associated with soil mineralogy, such as specific surface area and organic C loading, should be incorporated to generate more mechanistic models for predicting soil C saturation, but in their absence, statistical models should represent the upper envelope rather than the average value. [ABSTRACT FROM AUTHOR]

Labile organic carbon (LOC) is a critical component of soil organic carbon (C) because of its intimate association with soil heterotrophic respiration and role in the decomposition of resistant soil organic matter. In a subtropical moist evergreen broad-leaved forest of southwest China, we examined changes of LOC and its potential turnover time, microbial biomass C (MBC), and soil microbial activity of the organic and the 0-10 cm mineral soil layers with aboveground plant litter and belowground root treatments. In February of 2004, removal of organic layer, root-trenching, and tree-girdling treatments were applied alone and in combination to manipulate plant-C inputs. In 2006, root-trenching and tree-girdling treatments did not significantly change LOC in the organic layer. In the 0-10 cm mineral soil layer, LOC increased substantially due to tree-girdling treatment, especially in the plots of tree-girdling and the combinations of three treatments, but this increase was absent in 2007. Soil MBC in these two layers generally did not change markedly after plant-C inputs manipulations except significant increase under tree-girdling treatment in 2006. The potential turnover times of LOC increased in all plots with the plant-C inputs manipulations. The lack of influence of plant-C inputs manipulations on LOC pools is likely due to high total soil organic C here, while insignificant changes of MBC suggest the soil microbes are not C limited in this forest. The changes of the potential turnover time of LOC imply that the sources of LOC have been shifted from fresh plant litter or root exudates to old soil organic C. Our results suggest that LOC recently derived from plants is preferred by microbes when available, but microbes can also use LOC from soil organic matter when fresh plant C is not available. [ABSTRACT FROM AUTHOR]

Abstract: Soil respiration is a large component of global carbon fluxes, so it is important to explore how this carbon flux varies with environmental factors and carbon inputs from plants. As part of a long-term study on the chemical and biological effects of aboveground litterfall denial, root trenching and tree-stem girdling, we measured soil respiration for three years in plots where those treatments were applied singly and in combination. Tree-stem girdling terminates the flow of carbohydrates from canopy, but allows the roots to continue water and nutrient uptake. After carbon storage below the stem girdles is depleted, the girdled trees die. Root trenching immediately terminates root exudates as well as water and nutrient uptake. Excluding aboveground litterfall removes soil carbon inputs, but allows normal root functions to continue. We found that removing aboveground litterfall and the humus layer reduced soil respiration by more than the C input from litter, a respiration priming effect. When this treatment was combined with stem girdling, root trenching or those treatments in combination, the change in soil respiration was indistinguishable from the loss of litterfall C inputs. This suggests that litterfall priming occurs only when normal root processes persist. Soil respiration was significantly related to temperature in all treatment combinations, and to soil water content in all treatments except stem girdling alone, and girdling plus trenching. Aboveground litterfall was a significant predictor of soil respiration in control, stem-girdled, trenched and stem-girdled plus trenching treatments. Stem girdling significantly reduced soil respiration as a single factor, but root trenching did not. These results suggest that in addition to temperature, aboveground carbon inputs exert strong controls on forest soil respiration. [Copyright &y& Elsevier]

Abstract: Soil microbial activity drives carbon and nutrient cycling in terrestrial ecosystems. Soil microbial biomass is commonly limited by environmental factors and soil carbon availability. We employed plant litter removal, root trenching and stem-girdling treatments to examine the effects of environmental factors, above- and belowground carbon inputs on soil microbial C in a subtropical monsoon forest in southwest China. During the experimental period from July 2006 through April 2007, 2 years after initiation of the treatments, microbial biomass C in the humus layer did not vary with seasonal changes in soil temperature or water content. Mineral soil microbial C decreased throughout the experimental period and varied with soil temperature and water content. Litter removal reduced mineral soil microbial C by 19.0% in the ungirdled plots, but only 4.0% in girdled plots. Root trenching, stem girdling and their interactions influenced microbial C in humus layer. Neither root trenching nor girdling significantly influenced mineral soil microbial C. Mineral soil microbial C correlated with following-month plant litterfall in control plots, but these correlations were not observed in root-trenching plots or girdling plots. Our results suggest that belowground carbon retranslocated from shoots and present in soil organic matter, rather than aboveground fresh plant litter inputs, determines seasonal fluctuation of mineral soil microbial biomass. [Copyright &y& Elsevier]

• Mechanisms that attributed to the soil carbon reduction after converting SR to RP. • Changes in soil moisture, played role in accelerating of SOC decomposition in RP. • Converting SR to RP can increase Q 10 of R h from the original SR SOC. Land-use changes can alter carbon cycling. Soil carbon loss resulting from the conversion of natural forests to rubber plantations (RP) may occur due to changes in litter inputs or in biotic and abiotic environmental conditions. In this study, we conducted a reciprocal soil and litter translocation mesocosm experiment for 15 months in a seasonal rainforest (SR) and RP to elucidate the effect of litter, soil and site conditions on heterotrophic respiration and its temperature sensitivity after land-use conversion. We found that rate of soil heterotrophic respiration (R h) was higher at RP site than at SR site or for SR litter than RP litter with significant interactions between forest site and litter type, and did not differ between SR and RP soils. The Q 10 values of R h did not differ between forest sites, soils, or litter types but were substantially lower when litter was absent and substantially higher when RP soil was incubated in SR site and vice versa. Removal of surface litters led to a reduction of R h by 27-45%. Soil labile organic C pool and microbial biomass were not influenced by litter type or forest site, but were influenced by soil origin, with higher values for SR soil than RP soil. Soil temperature and moisture were not influenced by litter type and soil but differed between forest sites with higher moisture at RP site than SR site. Our results suggested that changes in physical environmental conditions, rather than changes in litter input or soil biochemical properties, attributed to the elevated soil heterotrophic respiration in RP, resulting in soil carbon loss following the tropical land-use changes. [ABSTRACT FROM AUTHOR]

A fundamental challenge in soil macroecology is to understand how microbial community structure shapes ecosystem function along environmental gradients of the land surface at broad spatial scales (i.e. the horizontal dimension). However, little is known about microbial community structure–function relationships in extreme environments along environmental gradients of soil depth at finer spatial scales (i.e. the vertical dimension). Here, we propose a general spatial dimension partitioning approach for assessing the patterns and drivers of soil microbial community structure–function relationships across horizontal and vertical spatial gradients simultaneously. We leveraged a 200‐km desert soil salinity gradient created by a 12‐year saline‐water irrigation in the Tarim basin of Taklamakan Desert. Specifically, using a general linear model, hierarchical variance partitioning, and a path model, we assessed the patterns and key ecological processes controlling spatial turnover in microbial community structure (i.e. β‐diversity) and enzymatic activity relevant to carbon, nitrogen, and phosphorus cycling along soil salinity gradients across study sites (horizontal dimension) and soil depths (vertical dimension). We found a decoupled relationship between soil microbial β‐diversity and enzymatic activity. Differences in soil depth (on the scale of meters) were as important as geographic distance (on the scale of kilometers) in shaping bacterial and fungal β‐diversity. However, the vertical and horizontal turnover in enzymatic activity was largely attributed to an increase in the heterogeneity of soil properties, such as soil texture, water content, and pH. Our findings suggest that dispersal limitation controls microbial community β‐diversity and that environmental heterogeneity, rather than soil salinization, controls enzymatic activity. Taken together, this work highlights that in the face of ongoing environmental alterations, soil depth is an under‐explored spatial dimension that must be considered in soil conservation efforts as a critical factor in determining microbial community structure and function in extreme environments. [ABSTRACT FROM AUTHOR]

Accurate estimate of C inputs to soils is important to improve the prediction of changes in global soil organic carbon (SOC) and SOC transformations in a microbial C cycle. In cropland crop yield are well documented and can be used to estimated C inputs accurately, thus processes in SOC biochemical cycle become critical to predict changes in SOC. We modeled the time series data of SOC stock and crop yield of multiple long-term agricultural trials that represent a range of climate, soil texture and agricultural management (e.g. fertilization and rotation) in China. The soil organic carbon (SOC) model comprised physical size and density fractions, where adsorption to minerals and occlusion in soil aggregates are considered as SOC stabilization mechanisms. Physical fractions contents in the model define soil aggregation state and thus a feedback with C stabilization due to spatial restrictions for microbial attack of occluded SOC.The inverse modeling was done with Nelder-Mead optimization algorithm to estimate the reaction rates of SOC transformations in different physical fractions and carbon use efficiency as a density-dependent function or community-level regulation parameters.The current modeling study with data of long-term SOC dynamics at known SOC inputs and texture allows us to improve the model constraints for estimating biological parameters of microbial decomposition for stable and labile organic matter in physical fractions. Further modeling results may inform us on unknown details of soil biochemical processes. [ABSTRACT FROM AUTHOR]

Improving the prediction of changes in global soil organic carbon (SOC) lies in accurate estimate of C inputs to soils and SOC turnover time. Since C inputs to soils in cropland can be estimated due to well documented data of crop yields, SOC turnover rate becomes critical for accurate prediction of changes in SOC. The laboratory incubation is widely used but cannot well represent the turnover of slow soil C that accounts for the majority of total SOC, while the long-term observation of temporal changes in SOC stock offers an opportunity to estimate the turnover of slow soil C. Using the time series data of SOC stock and crop yield of multiple long-term agricultural trials that represent a range of climate, soil properties (e.g. soil pH, texture, and mineralogy), and agricultural management (e.g. fertilization and rotation) in China, we estimated SOC turnover rates and aimed to identify the primary controls of SOC changes across Chinese cropland. We used the first-order kinetic soil C model and the inverse modeling with Markov chain the Monte Carlo algorithm to estimate the turnover rates of SOC fractions and carbon use efficiency. The preliminary results show that the turnover rate of slow soil C is positively correlated with climate (i.e. mean annual temperature and precipitation) but negatively correlated with the clay content, demonstrating that the clay content is important in regulating SOC turnover rates. Further results will inform us the main controls on SOC turnover in Chinese cropland. [ABSTRACT FROM AUTHOR]

Soil – the largest terrestrial pool of actively-cycling carbon – has the potential to sequester vast amounts of carbon globally. Chemical- and physical-associations of organic matter with mineral surfaces are known to play a critical role in this storage and preservation. However, the maximum capacity of soils to store carbon globally, and the role of mineralogy in driving this limit and its spatial variation, is still unknown. Here we present a comprehensive analysis of mineral-associated carbon and auxiliary variables from sites that span diverse biomes and soil types. We find that soil mineralogical properties dictate the maximum capacity of soils to stabilize organic matter associated with minerals, and that this mineral-associated organic matter accounts for the majority of carbon and nitrogen in soil organic matter. Explicit representations of mineral-organic associations are still lacking in Earth system models, and our findings are essential for informing and parameterizing model formulations at global scales. Our results suggest that most soils contain substantially less carbon than their mineral-associated carbon capacity (i.e., they are below carbon saturation), and that this is particularly evident in deeper soils and in poorly-managed and degraded lands. We calculate the mineralogical limit of low- and high-activity mineral soils to stabilize carbon, and use these empirically-derived limits to estimate the global potential for soil minerals to stabilize carbon. This estimate, and the underlying spatial distribution, provides crucial insights and motivation for targeted soil management and conservation efforts. Increasing soil carbon storage through restoration is a promising avenue for mitigating global emissions with lasting co-benefits. [ABSTRACT FROM AUTHOR]

The large volume expansion induced by K+ intercalation is always a big challenge for designing high‐performance electrode materials in potassium‐ion storage system. Based on the idea that large‐sized ions should accommodate big "houses," a facile‐induced growth strategy is proposed to achieve the self‐loading of MoS2 clusters inside a hollow tubular carbon skeleton (HTCS). Meantime, a step‐by‐step intercalation technology is employed to tune the interlayer distance and the layer number of MoS2. Based on the above, the ED‐MoS2@CT hybrids are achieved by self‐loading and anchoring the well‐dispersed ultrathin MoS2 nanosheets on the inner surface of HTCSs. This unique compositing model not only alleviates the mechanical strain efficiently, but also provides spacious "roads" (hollow tubular carbon skeleton) and "houses" (interlayer expanded ultrathin MoS2 sheets) for fast K+ transition and storage. As an anode of potassium‐ion batteries, the resultant ED‐MoS2@CT electrode delivers a high specific capacity of 148.5 mAh g−1 at 2 A g−1 after 10 000 cycles with only 0.002% fading per cycle. The assembled ED‐MoS2@CT//PC potassium‐ion hybrid supercapacitor device shows a high energy density of 148 Wh kg−1 at a power density of 965 W kg−1, which is comparable to that of lithium‐ion hybrid supercapacitors. [ABSTRACT FROM AUTHOR]

Purpose: Extreme online reviews can have great impacts on consumers' purchase decisions. The purpose of this paper is to investigate when users are more likely to provide extreme ratings. The study draws inference from attitude certainty theory and proposes that review extremity is influenced by the interaction of evaluation duration and product/service types: for hedonic products/services, shorter evaluation duration can foster attitude certainty, leading to higher review extremity; in contrast, for utilitarian products/services, longer evaluation duration can increase attitude certainty, resulting in more extreme reviews. Design/methodology/approach: Three studies were conducted to test the hypotheses: Study 1 is an empirical analysis of 3,000 reviews from an online retailing website; Studies 2 and 3 are two between-subject experiments. Findings: Results from three studies confirm the hypotheses. Study 1 provides preliminary evidence on how review extremity varies in evaluations of different durations and product/service types. Results from Studies 2 and 3 show that for hedonic products/services, the shorter the evaluation duration, the more likely users are to give extreme ratings; however, for utilitarian products/service, the longer the evaluation duration, the more likely users are to give extreme reviews; and attitude certainty plays a mediating role between evaluation duration and review extremity. Originality/value: Findings from this study provide understandings on when a fast rather than a slow evaluation can lead to more extreme reviews. The results also highlight the role of users' attitude certainty in the underlying mechanism. [ABSTRACT FROM AUTHOR]

Soil inorganic carbon (SIC) accounts for 30–70% of the total soil C in global drylands. Despite the slow turnover rate, recent studies indicate that SIC could be altered by land-use change as soil organic C (SOC). Neglecting SIC change could contribute greatly to the uncertainty of soil C dynamics in drylands. However, due to the spatial-temporal variation in SIC, the direction and magnitude of SIC change (rate) induced by land-use change at a large spatial scale is understudied and poorly understood. Here, we used the space-for-time approach to test how the SIC change varied with the duration and type of land-use change and soil depth across China's drylands. We assessed the temporal and spatial variations in the SIC change rate and explored the influencing factors based on a regional dataset comprising 424 pairs of data across North China. We found that the SIC change rate of 0–200 cm after land-use change was 12.80 (5.47‒20.03) g C m−2 yr−1 (mean with 95% confidence interval), which was comparable to the SOC change rate (14.72, (5.27-24.15 g C m−2 yr−1)). Increased SIC occurred only in deep soils (>30 cm) and in the conversion from deserts to croplands or woodlands. In addition, the SIC change rate decreased with the duration of land-use change, implying that quantifying the temporal pattern of SIC change is necessary to accurately estimate SIC dynamics. The SIC change was strongly related to changes in soil water content. The SIC change rate was weakly and negatively correlated with the SOC change rate, and this relationship varied with soil depth. Together, this study highlights that to improve the prediction of soil C dynamics following land-use change in drylands, we should quantify the temporal and vertical patterns of both soil inorganic and organic C changes in the region. [Display omitted] • Inorganic C of deep soils increased after land-use change across China's drylands. • The SIC change rate displayed a decreasing trend with duration of land-use change. • The SIC change rates after land-use change were comparable to the SOC change rates. • SIC changes were negatively and weakly correlated with SOC changes. [ABSTRACT FROM AUTHOR]

Soils are important carbon (C) reservoirs and play a critical role in regulating the global C cycle. Soil water potential (SWP) measures the energy with which water is retained in the soil and is one of the most vital factors that constrain the decomposition of soil organic C (SOC). The measurements for soil water retention curve (SWRC), on which the estimation of SWP depends, are usually carried out above −1.5 MPa (i.e., the wilting point for many plants). However, the average moisture threshold at which soil microbial activity ceases is usually below −10 MPa in mineral soils. Beyond the measurement range, the SWP estimation has to be derived from extrapolating the SWRC, which violates the statistical principle, resulting in possibly inaccurate SWP estimations. To date, it is unclear to what extent the extrapolated SWP estimation deviates from the "true value" and how it impacts the modeling of SOC decomposition. This study combined SWRC measurements down to −43.7 MPa, a 72‐day soil incubation experiment with four moisture levels, and an SOC decomposition model. In addition to the complete SWRC (SWRCall), we fitted two more SWRCs by using measurements above −0.5 MPa (SWRC0.5) and −1.7 MPa (SWRC1.7), respectively, to quantify the deviations of extrapolated SWPs from the complete SWRC. Results showed that extrapolating the SWRC beyond its measurement range significantly underestimated the SWP. Incorporating the extrapolated SWP in the model significantly underestimated the SOC decomposition under relatively dry conditions. With the extrapolated SWP, the model predicted no SOC decomposition in the driest treatment, while the experiment observed a significant CO2 emission. The results emphasize that accurate SWP estimations beyond the wilting point are critically needed to improve the modeling of SOC decomposition. [ABSTRACT FROM AUTHOR]

Highlights: [•] Proteomes of ‘Zaosu’ pear and its early-maturing bud sport were compared. [•] The most proteins were linked to metabolism, oxidative stress and cell structure. [•] XTH and α-Man involved in cell-wall loosening were up-regulation. [•] Glycolysis and photosynthesis-related metabolisms were down-regulation. [Copyright &y& Elsevier]

Straw return as a common and effective management can improve soil carbon (C) sequestration and structure by forming aggregates and aggregate associated C. Quantifying soil aggregation and aggregate associated C is key to predicting soil organic C dynamics using testable models. The relative quantity of C stabilized in soil aggregate is an indicator that can reveal the conversion efficiency of added straw to organic C in aggregate. Straw size is known to alter litter decomposition, but how straw size impacts the dynamics of soil aggregate formation and the relative quantity of C stabilized in soil aggregate after litter addition is not well understood. We conducted an 80-day laboratory incubation with wheat straw addition of two different sizes (1–2 mm and <0.25 mm) to artificial soils of two textures (3 % clay and 7 % clay). The objectives were to examine 1) whether straw size significantly modified litter decomposition and the relative quantity of C stabilized in soil aggregates over time, and 2) what soil physical and biochemical factors determined soil aggregation and the formation of aggregate-associated C over time, such as straw size, soil texture, or enzyme activity. We found that both litter decomposition and the relative quantity of C stabilized in soil aggregates were higher in the treatment with small straw addition than those with large straw addition, but they were not significantly different between two soils with 3 % vs. 7 % clay content. This was due to increased enzyme activities caused by small straw addition, which could enhance dissolved organic C generation and stimulate microbial decomposition. Additionally, the mass proportion of macroaggregate (>2 mm) increased with time while the mass proportion of microaggregate (0.25–2 mm) decreased, suggesting that microaggregate combined to form macroaggregate (>2 mm) in the late stage of incubation (after day 17). Moreover, the relative quantity of C stabilized in microaggregate (<0.053 mm) increased linearly with dissolved organic C, whereas the relative quantity of C stabilized in macroaggregate (>2 mm) increased with the aromaticity of dissolved organic matter as measured by specific ultraviolet absorbance at 254 nm. Together, our findings suggest that straw size remarkably modifies litter decomposition and the relative quantity of C stabilized in soil aggregates by changing the quantity and quality of dissolved organic C at different decomposition stages, whereas small difference in soil clay content has no effects. ● The relative quantity of carbon stabilized in aggregates was higher with small-straw addition than with large-straw addition. ● The relative quantity of carbon stabilized in micro- and macro-aggregates showed opposite trends with time. ● Enzymatic activities were positively related to CO 2 respiration rate after straw addition. ● Dissolved organic C was positively related to the relative quantity of C stabilized in microaggregate (<0.053 mm). ● SUVA 254 was positively related to the relative quantity of C stabilized in large macroaggregate (>2 mm). [ABSTRACT FROM AUTHOR]

• Soil organic carbon (C) content exhibits an increasing trend with elevation (from 481 to 3035 m) in arid regions. • Exchangeable Ca2+ predominantly governs soil organic C content at high elevations. • Amorphous iron is the most important predictor of soil organic C content at low elevations. • Soil Ca2+ competes with iron at high elevations but assists iron at low elevations for organic C stabilization. Elevational gradients offer powerful natural experiments for testing how soil organic carbon (SOC) responds to environmental changes (e.g., climate, plant inputs, and soil geochemistry) across a wide range. Exchangeable calcium (Ca ex) emerges as an important geochemical driving factor of SOC content in arid regions, yet its significance in regulating SOC content across climatic gradients remains poorly understood. Here, we assessed the relative importance of climate variables, plant inputs, and geochemical properties in controlling SOC content along a 2,500-m elevational gradient in the Tianshan Mountains. We explored the roles of Ca ex in regulating the interactions between iron (Fe)-(hydro)oxides and SOC content. We found that soil Ca ex (i.e., Na 2 SO 4 -extracted), likely controlled by biological cycling, was the major contributor to SOC content in cold and wet climatic conditions (1,400–3,035 m a.s.l.), where soils had relatively high Fe o and low pH (5.8‒7.9). In contrast, amorphous Fe, not Ca ex , was the most important regulator for SOC content in warm and dry climatic conditions (481–1,240 m a.s.l.) with Ca-rich and high pH soils (7.6‒9.0). Moreover, the results of partial correlation analysis suggested that Ca ex competed with Fe-(hydro)oxides in modulating SOC content in cold and wet climatic conditions due to low soil pH, but facilitated SOC stabilization by Fe-(hydro)oxides in warm and dry climatic conditions. Although climatic variables and plant inputs were significantly associated with SOC content, our findings indicated that Ca ex and Fe-(hydro)oxides had divergent controls over SOC content across climatic gradients in arid regions, depending on soil pH level. Our study reveals new insights on the potential role of cations in complexation of organic matter with minerals across a wide range of environmental conditions in the field. [Display omitted] [ABSTRACT FROM AUTHOR]

• Electrolyte is optimized for low-temperature LiFePO 4 -graphite battery. • Multi-component solvent system improves the ionic conductivity at low temperature. • Film-forming additives promote the formation of solid electrolyte interface film. • The optimized battery exhibits excellent performance at low temperatures. The design of electrolyte is crucial to improve the low temperature electrochemical performance of the LiFePO 4 -graphite battery. In this paper, by optimizing the solvent composition and introducing film-forming additives in the electrolyte, the low temperature performance of the battery is significantly improved. In detail, the EP (ethyl propionate) solvent with low melting point and low viscosity is added to the original EC (ethylene carbonate)-EMC (ethyl methyl carbonate)-DMC (dimethyl carbonate) solvent systems, which improved the ionic conductivity of the electrolyte, especially at low temperature (−40 °C). On the other hand, the introduction of FEC (fluoroethylene carbonate)/DTD (ethylene sulfate) film-forming agents promotes the formation of SEI (solid electrolyte interface) film, and the SEI is thin and uniform. As a result, the LiFePO 4 -graphite battery exhibits high capacity and long cycle life under low temperature conditions. [ABSTRACT FROM AUTHOR]

Quantifying the upper limit of stable soil carbon storage is essential for guiding policies to increase soil carbon storage. One pool of carbon considered particularly stable across climate zones and soil types is formed when dissolved organic carbon sorbs to minerals. We quantified, for the first time, the potential of mineral soils to sorb additional dissolved organic carbon (DOC) for six soil orders. We compiled 402 laboratory sorption experiments to estimate the additional DOC sorption potential, that is the potential of excess DOC sorption in addition to the existing background level already sorbed in each soil sample. We estimated this potential using gridded climate and soil geochemical variables within a machine learning model. We find that mid- and low-latitude soils and subsoils have a greater capacity to store DOC by sorption compared to high-latitude soils and topsoils. The global additional DOC sorption potential for six soil orders is estimated to be 107 ± 13 Pg C to 1 m depth. If this potential was realized, it would represent a 7% increase in the existing total carbon stock. [ABSTRACT FROM AUTHOR]

Incorporating plant litter into soil can replenish soil organic carbon (SOC) through physical protection mechanisms, such as formation of mineral-organic complexes and aggregates. Meanwhile, plant litter input may stimulate the decomposition of native SOC, known as the priming effect. It remains unclear how these physical protection mechanisms affect the priming effect, which further affects the SOC dynamics. Here, we present a novel model that can predict the dynamics of protected and primed organic carbon in soil and aggregates (PROCAAS). The PROCAAS model assumes that microbial activity will control the dynamics of both aggregate turnover and the priming effect following litter incorporation, and that litter-derived SOC will prime the decomposition of the native SOC pool as they are in the same location and in the same pool, either occluded in soil pores or associated with minerals. The PROCAAS model was well calibrated and validated using independent datasets of aggregate mass proportion and aggregated SOC contents in literature as well as soil respiration and the priming effect measured here during 76-day incubation with and without 13C labeled litter. The model results showed that litter-derived SOC was protected predominantly through occlusion in macroaggregates, while the priming effect was originated mainly from mineral-associated SOC in macroaggregates. The dynamics of priming effect could be explained by the soil structural change from soil disaggregation during litter incorporation, via the formations of macroaggregates and microaggregates within macroaggregates, to the aggregate stability during litter decomposition. Our proof-of-concept model can form the base for incorporating these biophysical mechanisms underlying soil aggregation and the priming effect into future ecosystem models. Image 1 • A new soil carbon model (PROCAAS) was developed. • PROCAAS coupled aggregation, C pool transformation and interactions. • Litter C was mainly protected through occlusion in macroaggregates. • Priming effect led to loss mineral-associated soil carbon in macroaggregates. • Priming dynamics were controlled by disaggregation and aggregation. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) can be defined by measurable chemical and physical pools, such as mineral-associated carbon, carbon physically entrapped in aggregates, dissolved carbon, and fragments of plant detritus. Yet, most soil models use conceptual rather than measurable SOC pools. What would the traditional pool-based soil model look like if it were built today, reflecting the latest understanding of biological, chemical, and physical transformations in soils? We propose a conceptual model-the Millennial model-that defines pools as measurable entities. First, we discuss relevant pool definitions conceptually and in terms of the measurements that can be used to quantify pool size, formation, and destabilization. Then, we develop a numerical model following the Millennial model conceptual framework to evaluate against the Century model, a widely-used standard for estimating SOC stocks across space and through time. The Millennial model predicts qualitatively similar changes in total SOC in response to single factor perturbations when compared to Century, but different responses to multiple factor perturbations. We review important conceptual and behavioral differences between the Millennial and Century modeling approaches, and the field and lab measurements needed to constrain parameter values. We propose the Millennial model as a simple but comprehensive framework to model SOC pools and guide measurements for further model development. [ABSTRACT FROM AUTHOR]

The understanding of soil microbial resource limitation has important implications for belowground nutrient cycling. Climate is a primary factor that regulates microbial resource limitation directly and indirectly. Elevational gradient has been used as a substitution of latitudinal gradient in ecological studies because the former displays a wide range of climate variation as the latter. However, whether the elevational trend of microbial resource limitation follows that of latitudinal pattern is still not well known. Here we aimed to 1) test the elevational patterns (465–3035 m a.s.l.) of microbial carbon (C) and nutrient (P: N) limitations in the Tianshan Mountain by using the enzymatic vector analysis, and 2) examine the importance of microclimate and soil resource in regulating microbial C and P:N limitation along the elevational gradient. We found that microbial C limitation generally decreased and microbial P:N limitation increased with increasing elevation, which were the opposite to those of latitudinal patterns. Our results further indicated that microbial C limitation was primarily controlled by soil microclimate with soil moisture alleviating microbial C limitation in the warm & dry climatic condition (465–1240 m a.s.l.) but intensifying in the cold & wet climatic condition (1400–3035 m a.s.l.). Microbial P:N limitation was mainly regulated by soil available P and by the shared effects of soil microclimate and resource. Moreover, microbial C limitation was negatively correlated with microbial P:N limitation, which implied that soil C and nutrient supplies were strongly coupled. Overall, the spatial changes of microbial resource limitation cannot be simply inferred from latitude to altitude or vice versa, instead we should focus on how the determinants of microbial resource limitation change along these environmental gradients. [ABSTRACT FROM AUTHOR]

Unprecedented levels of nitrogen (N) have been deposited in ecosystems over the past century, which is expected to have cascading effects on microbially mediated soil respiration ( SR). Extracellular enzymes play critical roles on the degradation of soil organic matter, and measurements of their activities are potentially useful indicators of SR. The links between soil extracellular enzymatic activities ( EEAs) and SR under N addition, however, have not been established. We therefore conducted a meta-analysis from 62 publications to synthesize the responses of soil EEAs and SR to elevated N. Nitrogen addition significantly increased glycosidase activity ( GA) by 13.0%, α-1,4-glucosidase ( AG) by 19.6%, β-1,4-glucosidase ( BG) by 11.1%, β-1,4-xylosidase ( BX) by 21.9% and β-D-cellobiosidase ( CBH) by 12.6%. Increases in GA were more evident for long duration, high rate, organic and mixed N addition (combination of organic and inorganic N addition), as well as for studies from farmland. The response ratios ( RRs) of GA were positively correlated with the SR- RRs, even when evaluated individually for AG, BG, BX and CBH. This positive correlation between GA- RR and SR- RR was maintained for most types of vegetation and soil as well as for different methods of N addition. Our results provide the first evidence that GA is linked to SR under N addition over a range of ecosystems and highlight the need for further studies on the response of other soil EEAs to various global change factors and their implications for ecosystem functions. [ABSTRACT FROM AUTHOR]

A NS-C@b-MoS 2 hybrid is readily fabricated with bilayer MoS 2 molecules grafted onto 3D N/S doped carbon capsule skeleton in one tailored spatial-chemical doubly confined mode. The MoS 2 bilayer can expose more S-Mo-S bonds to adsorb K-ions. Together with the support effect of carbon skeleton, consequently, this NS-C@b-MoS 2 hybrid electrode achieves an ultra-fast and ultra-stable potassium-ion storage capability. [Display omitted] • A tailored induced vapour-deposition strategy to construct a MoS 2 /C hybrid. • MoS 2 with bilayer structure can expose more S-Mo-S bonds to adsorb K-ions. • One spatial-chemical doubly confined mode to enhance the MoS 2 bilayer stability. • The assembled PIC deliver an ultra-stable performance up to 65,000 cycles. Few-layers MoS 2 -based materials have a comprehensive advantage in accommodating potassium-ions due to the rich active S-Mo-S sites and rapid ionic dynamics. Unfortunately, the serious self-stacking of MoS 2 molecular layer resulted in insufficient space to buffer the stress/strain caused by K-ions intercalation, which makes MoS 2 -based electrode exhibits low capacitance and poor cyclic stability in practical studies. To solve this, an in situ induced deposition strategy is proposed to construct a MoS 2 /C hybrid (labelled as NS-C@b-MoS 2). In this NS-C@b-MoS 2 hybrid, the MoS 2 molecular with bilayer structure is grafted onto a 3D N/S dual-doping carbon skeleton in one spatial-chemical doubly confined mode. This unique hybrid mode not only expose more S-Mo-S bonds to adsorb K-ions, but also avoid the structural collapse of electrode by spatial-chemical doubly confinement effect of carbon skeleton. Consequently, the resultant NS-C@b-MoS 2 anode delivers a high specific capacity of 451.2 mAh g−1 at 0.1 A g−1 and an ultra-long cycle stability up to 20,000 cycles with only 0.0013 % fading per cycle. Moreover, the assembled NS-C@b-MoS 2 //NSAC potassium-ion capacitor delivers a high energy density of 126.5 Wh kg−1 and retains 55.2 Wh kg−1 after 65,000 cycles at 3800 W kg−1, which over the state-of-the-art reported performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • The OPID approach, could determine an OPtimal Incubation Duration for ongoing incubation experiment. • SOC decomposability were underestimated or overestimated when incubation period was short. • The accuracy of model projections increases with incubation period but diminishes when longer than an optimum. • Model performs better under lower temperature but reversed with increasing incubation period. Laboratory incubation is a commonly used method to measure the decomposition of soil organic carbon (SOC). While incubation experiments are conducted across a wide range of durations that may vary from hours to years, no method is available to determine an optimal duration of the incubation experiment so that SOC decomposition can be best understood. Here we presented a novel approach to determine the optimal duration called OPtimal Incubation Duration (OPID). The OPID approach quantifies information gained from an ongoing incubation experiment and determines the time point when SOC decomposition rates can be well quantified. Statistically, the OPID approach is based on a progressive data assimilation algorithm that iteratively assimilates data from an ongoing incubation experiment into a three-pool first-order SOC decomposition model. Using a published incubation data set under different temperatures as a case study, we first generated synthetic daily data, and then fed the data into the three-pool model iteratively to observe the changes of model performance. We found that the accuracy of model projections increased with incubation period and exhibited a trade-off between initial model performance and the time towards accurate projection among different temperatures of incubation. The optimal incubation duration was 347, 212, and 126 days under incubation temperatures of 15 °C, 25 °C and 35 °C, respectively. Comparing the parameters with which from the synthetic daily data, if the incubation period was shorter than the optimal durations, then the decomposition rate of the fast-turnover pool was underestimated and those of the slow pools were overestimated. Sensitivity analysis indicated that optimal incubation duration was negatively correlated with proportion of slow-turnover carbon pools, turnover rates, and initial carbon content, respectively. Our study suggested that long-term incubation experiments are necessary for capturing the dynamics of slow-turnover carbon pools. However, the additional data may not be helpful for model performance if the incubation duration is longer than the optimum. Our study provides a tool for soil scientists to design more effective incubation experiments. DA: data assimilation; PDA: progressive data assimilation; Cum CO 2 : cumulative CO 2 emission from soil; opt: optimal duration; [ABSTRACT FROM AUTHOR]

[Display omitted] • Microbial specific growth rates, active microorganisms portion and enzyme activity increase with cropland abandonment. • Microbial community shifts from K - to r -strategy with cropland abandonment. • Enzyme production increases with microbial growth and the portion of active microorganisms. • Microbial carbon use efficiency is directly affected by soil organic C content, pH, and the portion of active microorganisms. Microorganisms are critical for litter decomposition, organic carbon (C) and nutrient transformations in soil, corresponding to the vegetation succession. The dynamics of microbial activities and ecological functions during the soil recovery after agricultural land use (post-agricultural restoration) remains unclear. We investigated the effects of vegetation and soil restoration duration on active microbial biomass, microbial growth rates, C use efficiency (CUE, analyzed by 14C glucose utilization), and enzyme activities in three soil types of Russia: Haplic Luvisol in a deciduous forest (chronosequence from 0 to 37 years), Luvic Phaeozem in forest steppe (0–66 years), and Haplic Phaeozem in forest steppe (0–42 years). The microbial CUE (0.66–0.82) decreased during restoration and was highly dependent on soil type: the lowest in Luvisol and the highest in Haplic Phaeozem. The activities of β-1,4-glucosidase, β-1,4-N-acetylglucosaminidase, leucine aminopeptidase, and acid phosphatase increased during post-agricultural restoration. Microbial growth rates and the proportion of active microorganisms increased with restoration, reflecting a shift of microbial community to fast-growing decomposers (mainly r strategists) caused by large litterfall from recovered natural vegetation. The increase of the portion of active microorganisms and microbial growth rates was correlated with activities of enzymes responsible for C, N and P cycling. In conclusion, the post-agricultural restoration activates microorganisms, raises microbial growth, increases enzyme activities and accelerates microbially-mediated C and nutrient turnover. [ABSTRACT FROM AUTHOR]

[Display omitted] • SOM was mostly derived from plant litter rather than microbial residues. • SOM was associated with vermiculite via surface adsorption. • SOM was associated with illite and kaolinite through pore entrapment. • More plant carbohydrates were associated with 2:1 rather than 1:1 clay minerals. • SOM formation efficiency was affected by clay mineral type more than by plant litter type. Plant litters incorporated in soils are decomposed by microorganisms and partially transformed into soil organic matter (SOM) through mineral-organic association and physical protection in soil aggregates. Few studies have linked the effects of clay mineralogy and plant litter quality on controlling the formation efficiency of SOM. Using model soils, the objectives of this study were (1) to determine the effects of clay mineral type and plant litter quality on soil respiration dynamics, and formation efficiency of SOM, physical fractions, and chemical and microbial compositions of SOM at the end of a 120-day incubation; (2) to unravel SOM protection mechanisms and extents by specific clay minerals; and (3) to understand the key role of clay minerals relative to plant litter quality in controlling SOM formation. The changes in X-ray diffraction peak intensity (in terms of peak height) of the clay minerals during incubation and after H 2 O 2 treatment provided evidence for surface adsorption by vermiculite and pore entrapment by kaolinite and illite assemblages. The SOM protection extent parameter, defined based on accumulative soil respiration dynamics, explained well the variation of the formation efficiency of mineral associated SOM (MAOM) and, to a lesser extent, that of occluded particulate SOM (oPOM) in aggregates. 90–96% of plant litter-derived C was protected in the vermiculite material and 33–60% in the pure kaolinite and illite materials. The pure vermiculite material showed the greatest fractions of MAOM and oPOM, the highest relative abundances of O–alkyls and anomeric from carbohydrates in the MAOM fraction. < 1% of plant litter-derived C was transformed into microbial biomass and residues, and fungal residues only were associated with the pure vermiculite material. These results suggested that plant litter incorporated into the soil was decomposed mainly through the ex vivo modification pathway and transformed into SOM through both mineral-organic association and physical protection pathways. Plant litter-derived C was likely protected through mineral-organic association from the earlier stages of decomposition by vermiculite than kaolinite and illite, resulting in more plant carbohydrates associated with vermiculite. Therefore, clay minerals determined SOM formation pathways and played a greater role in controlling SOM formation efficiency than plant litter quality. [ABSTRACT FROM AUTHOR]

• Soil organic carbon (SOC) increased over time in mangrove forest, while not in S. alterniflora sites. • Labile organic carbon (LOC) increased over time in Spartina alterniflora sites. • The proportion of resistant SOC increased over time in mangroves, contributed to SOC stabilization. Labile fractions of soil carbon pools are sensitive to environmental changes, which would influence the stabilization of soil carbon. However, it is unclear whether the dynamics of labile organic carbon (LOC) and soil organic carbon (SOC) are coupled and how they influence each other in coastal wetland. The present work investigated the trends of soil carbon fractions among mangrove and Spartina alterniflora communities with different stand ages (1, 5, 10, and 15 years), at Quanzhou Bay Estuary Wetland Nature Reserve, China. We found that SOC in a mangrove ecosystem increased over time, while there was no significant trend in S. alterniflora dominated ecosystems. The highest LOC of mangrove appeared in 5-year-old communities, and then decreased with stand age. In S. alterniflora communities, content of labile fractions increased with the stand age. These trends indicated different soil carbon dynamics when comparing mangrove and S. alterniflora ecosystems. The development of mangroves promoted accumulation of recalcitrant carbon, while S. alterniflora ecosystems contributed to an increase of labile carbon. This phenomenon is probably caused by the characteristics of vegetation and the hydrological conditions. Mangroves contribute more refractory organic carbon to the soil carbon pool, while accumulation of LOC in S. alterniflora communities may inhibit the stabilization of SOC. Our study on the relationship of LOC and SOC implies that complex interactions occur among soil carbon pools and environmental conditions in coastal wetlands, suggesting soil carbon models should take into account decoupled dynamics of LOC and SOC. [ABSTRACT FROM AUTHOR]

Soil microbial biomass is key to improving the prediction of soil organic carbon (SOC) dynamics by modeling. However, the driving mechanism of microbial biomass of different groups with soil depth is poorly understood across sites. Here, we compiled the biomass of different microbial groups (i.e., fungi, bacteria, gram-positive bacteria G+, and gram-negative bacteria G-) from the surface to a soil depth of 1 m from 71 soil profiles across three continents. We found that the biomass of microbial groups all decreased with soil depth but at different magnitudes, while the relative abundance of microbial groups, except G-, was relatively stable along soil profiles. Soil fungal biomass had a shallower vertical distribution than bacteria, especially G+, with 89% fungi and 76% G+ in the top 10 cm soils. In addition, a greater proportion of microbial biomass (71–89%) compared to SOC (64%) was in the top 10 cm soils, suggesting that microbes and SOC exhibited different vertical distributions. The vertical distributions of microbial biomass of different groups were significantly correlated with SOC and clay content but not with climate, and these distributions were different among land uses, highlighting the great influences of edaphic factors on vertical distributions of microbial biomass. The relationship between microbial biomass and soil depth provides a feasible way to estimate microbial biomass at different soil depths, which can serve as a benchmark to improve the prediction of SOC dynamics of entire soil profile at large scales. [Display omitted] • Absolute biomass not relative abundance of microbes decreases with soil depth. • Fungal biomass has shallower vertical distributions than bacterial biomass. • ~80% microbial biomass and 64% soil organic C are distributed in 0–10 cm soils. • Vertical distributions of microbial biomass are regulated by substrates and clay content. [ABSTRACT FROM AUTHOR]

Saline-sodic soils cover ∼10% of the global land surface and deliver various ecosystem services to human society in the arid/semiarid regions. Flue gas desulfurization gypsum (FGDG), a byproduct from coal-fired power plants, is widely used to ameliorate saline-sodic soils. Here, we aimed to quantify the impacts of FGDG application on multiple soil functions across climatic conditions, management practices, and soil types, and to explore how FGDG application affects plant productivity. We conducted a meta-analysis by compiling 2658 pairs of data points with and without FGDG application from 59 locations across China. We found that FGDG application significantly increased crop yield by 91.2% ± 22.5% (mean ± 95% CI) regardless of local climate and soil type, and improved soil quality by reducing soil exchangeable sodium percentage (ESP) by 37.4% ± 9.6% and pH by 8.1% ± 1.7%. Increases in soil productivity were strongly correlated with decreases in soil ESP and pH, suggesting that increases in soil productivity were due to alleviated stress for plant growth. Meanwhile, some heavy elements (e.g., Hg and Ni) increased after FGDG application, likely imposing threats to soil health. Overall, the FGDG application is effective in improving the quality and productivity of saline-sodic soils across China. Our findings suggest that simultaneous assessment of changes in soil water (e.g., water holding capacity and infiltration), nutrient transformation, soil organic matter dynamics, and microbial communities helps disentangle mechanisms that are responsible for optimizing ecosystem service provided by saline-sodic soils after FGDG amendment application. • FGDG application significantly reduces soil pH and salinity in different magnitudes. • FGDG application significantly increases crop yield and plant seedling emergence. • Enhanced plant productivity after FGDG application is due to reduced soil salinity. • FGDG application may posit negative environmental impacts of saline-sodic soils. [ABSTRACT FROM AUTHOR]

Small changes in soil organic carbon (SOC) may have great influences on the climate-carbon (C) cycling feedback. However, there are large uncertainties in predicting the dynamics of SOC in soil profiles at the global scale, especially on the role of soil microbial biomass in regulating the vertical distribution of SOC. Here, we developed a database of soil microbial biomass carbon (SMBC), SOC, and soil microbial quotient (SMQ = SMBC/SOC) from 289 soil profiles globally, as well as climate, ecosystem types, and edaphic factors associated with these soil profiles. We assessed the vertical distribution patterns of SMBC and SMQ and the contributions of climate, ecosystem type, and edaphic condition to their vertical patterns. Our results showed that SMBC and SMQ decreased exponentially with soil depth, especially within the 0–40 cm soil depth. SOC also decreased exponentially with depth but in different magnitudes compared to SMBC and SMQ. Edaphic factors (e.g. , soil clay content and C/N ratio) had the strongest control on the vertical distributions of SMBC and SMQ, probably by mediating substrate and nutrient supplies for microbial growth in soils. Mean annual temperature and ecosystem types (i.e. , forests, grasslands, and croplands) had weak influences on SMBC and SMQ. In contrast, the vertical distribution of SOC was significantly affected by climate and edaphic factors. Climate and ecosystem types likely simultaneously affected multiple factors that control SMBC, such as the distribution of soil clay and nutrients along soil profiles. Overall, our data synthesis provides quantitative information of how SMBC, SMQ, and SOC changed along soil profiles at large spatial scales and identifies important factors that influence their vertical distributions. The findings can help improve the prediction of C cycling in terrestrial ecosystems by incorporating the contribution of soil microbes in Earth system models. Image 1 • A comprehensive dataset was collected for soil organic C and microbial biomass along soil profiles. • Vertical distributions and main driving factors were assessed. • Soil microbial biomass and its ratio to soil organic C decreased with soil depth at large spatial scales. • Edaphic not climatic conditions drove vertical distributions of soil microbial biomass. • This synthesis highlights the importance of microbial roles in soil C cycling. [ABSTRACT FROM AUTHOR]