Abstract Forests provide a huge carbon pool, a substantial portion of which is stored in above-ground biomass (AGB). Deciduous broadleaf forests in China are an essential component of global deciduous broadleaf forests, yet the impacts of climate and forest attributes on their AGB are not well understood. Using a comprehensive forest inventory database from 772 plots distributed across temperate and subtropical deciduous broadleaf forests in China (23.51°?42.53°N and 104.24°?128.27°E), we applied variance partitioning analysis, model selection analysis and structural equation models to explore how climate and forest attributes (species diversity, community-level functional traits and stand structures) affect AGB in different climatic forests (semi-arid forests, semi-humid forests and humid forests). Community-level functional traits and stand structures together explained a great portion of the variance in AGB. The effect of community-level functional traits was greater than that of stand structures in semi-arid forests and semi-humid forests, but smaller in humid forests. Further analyses showed that community-level maximum tree height, stem density and tree size inequality were important explanatory variables. Although climate and species diversity had minor effects, the direct positive effect of mean annual precipitation (MAP) was still important, especially in semi-arid forests. Synthesis. Community-level functional traits but not species diversity were key drivers of AGB, indicating that tree species diversity loss may not impair AGB substantially in deciduous broadleaf forests in China. Moreover, stand structures also had strong effects on AGB in both semi-arid forests and humid forests, highlighting the importance of structural complexity. In addition, MAP had a direct positive effect on AGB in semi-arid forests and semi-humid forests, and a future increase in drought might potentially reduce carbon storage in these forests.
Global climate change has led to the decline of species and functional diversity in ecosystems, changing community composition and ecosystem functions. However, we still know little about how species with different resource-use strategies (different types of resource usage and plant growth of plants as indicated by the spectrum of plant economic traits, including acquisitive resource-use strategy and conservative resource-use strategy) would change in response to climate change, and how the changes in the diversity of species with different resource-use strategies may influence community-level productivity. Here, using long-term (1982–2017) observatory data in a temperate grassland in Inner Mongolia, we investigated how climate change had affected the species richness (SR) and functional richness (FRic) for the whole community and for species with different resource-use strategies. Specifically, based on data for four traits representing leaf economics spectrum (leaf carbon concentration, leaf nitrogen concentration, leaf phosphorus concentration, and specific leaf area), we divided 81 plant species appearing in the grassland community into three plant functional types representing resource-acquisitive, medium, and resource-conservative species. We then analyzed the changes in community-level productivity in response to the decline of SR and FRic at the community level and for different resource-use strategies. We found that community-level SR and FRic decreased with drying climate, which was largely driven by the decline of diversity for resource-acquisitive species. However, community-level productivity remained stable because resource-conservative species dominating this grassland were barely affected by climate change. Our study revealed distinctive responses of species with different resource-use strategies to climate change and provided a new approach based on species functional traits for predicting the magnitude and direction of climate change effects on ecosystem functions.
Flowering phenology of plants, which is important for reproductive growth, has been shown to be influenced by climate change. Understanding how flowering phenology responds to climate change and exploring the variation of this response across plant groups can help predict structural and functional changes in plant communities in response to ongoing climate change. Here, we used long-term collections of 33 flowering plant species from the Gongga Mountains (Mt. Gongga hereafter), a biodiversity hotspot, to investigate how plant flowering phenology changed over the past 70 years in response to climate change. We found that mean flowering times in Mt. Gongga were delayed in all vegetation types and elevations over the last 70 years. Furthermore, flowering time was delayed more in lowlands than at high elevations. Interestingly, we observed that spring-flowering plants show earlier flowering times whereas summer/autumn plants show delayed flowering times. Non-synchronous flowering phenology across species was mainly driven by changes in temperature and precipitation. We also found that the flowering phenology of 78.8% plant species was delayed in response to warming temperatures. Our findings also indicate that the magnitude and direction of variation in plant flowering times vary significantly among species along elevation gradients. Shifts in flowering time might cause trophic mismatches with co-occurring and related species, affecting both forest ecosystem structure and function.
One of the most important mechanism design policies in college admissions is to let students choose a college major sequentially (college-then-major choice) or jointly (college-major choice). In the context of the Chinese meta-major reforms that transition from college-major choice to college-then-major choice, we provide the first experimental evidence on the information frictions and heterogeneous preferences that students have in their response to the meta-major option. In a randomized experiment with a nationwide sample of 11,424 high school graduates, we find that providing information on the benefits of a meta-major significantly increased students’ willingness to choose the meta-major; however, information about specific majors and assignment mechanisms did not affect students major choice preferences. We also find that information provision mostly affected the preferences of students who were from disadvantaged backgrounds, lacked accurate information, did not have clear major preferences, or were risk loving.
The commercialization of academic patents is a basic means for universities to promote economic growth and upgrade the industrial innovation of enterprises. However, among developing countries, the commercialization rate of university patents is generally low. This study utilizes data from 65 universities which are directly under the Ministry of Education of China to analyze the influencing factors and mechanisms of academic patent commercialization. The findings show that the proportion of associate professors, the size of service staff transforming research and development achievement, and the proportion of basic research funding in universities are positively correlated with the commercialization rate of university patents. In addition, these factors indirectly affect the commercialization of university patents by affecting neighboring universities; that is, there are spatial spillover effects in the commercialization of university patents between neighboring universities. These empirical results indicate that universities can promote the commercialization of university patents by optimizing the structure of faculty, developing the R&D achievement transformation service staff team, and strengthening investment in basic research.
Because of land privatisation and marketisation in rural areas, community-based adaptation to climate change may face new challenges. A field survey conducted on the Qinghai–Tibetan Plateau (QTP) shows that herders with a grassland collective management system (CMS) suffer higher livestock mortality than those with an individual management system (IMS) during the same extreme climatic events, in contrast to previous research findings. This study seeks to explain this contrast. The results show that although local herders have begun to rely on market-related adaptation strategies to cope with climate change, IMS herders are more inclined to rent-in grassland, while CMS herders are more inclined to purchase fodder. The high-cost grassland renting-in strategy reduces livestock mortality and total household economic loss more effectively than purchasing fodder during snow disasters. An important reason for this is that IMS strengthens market concepts and promotes interaction between herders and external markets, especially the grassland rental market, while CMS continues past grazing traditions and maintains traditional social relationships and collective concepts within the community. CMS herders fail to rent-in grassland due to psychological free-riding incentives and scale mismatch. In the face of repeated climatic disasters, however, CMS herders have also begun to overcome various obstacles to entering the grassland rental market through self-organization and are gradually forming a new pathway of adaptation to climate change.
The poor colloidal stability of magnetite nanoparticles (MNPs) limits their mobility and application, so various organic coatings (OCs) were applied to MNPs. Here, a comparative study on the colloidal stability of MNPs coated with acetic (HAc) and polyacrylic acids (PAA) was conducted under varied pH (5.0–9.0) in the presence of different concentrations of cations and anions, as well as humic acid (HA). Comparing the effects of various cations and anions, the stability of both HAc/PAA-MNPs followed the order: Na+ > Ca2+and PO43− > SO42− > Cl−, which could be explained by their adsorption behaviors onto HAc/PAA-MNPs and the resulting surface charge changes. Under all conditions even with more anion adsorption onto HAc-MNPs (0.14–22.56 mg/g) than onto PAA-MNPs (0.04–18.34 mg/g), PAA-MNPs were more negatively charged than HAc-MNPs, as PAA has a lower pHIEP (2.6 ± 0.1) than that of HAc (3.7 ± 0.1). Neither the HAc nor PAA coatings were displaced by phosphate even at considerably high phosphate concentration. Compared with HAc-MNPs, the stability of PAA-MNPs was greatly improved under all studied conditions, which could be due to both stronger electrostatic and additional steric repulsion forces among PAA-MNPs. Besides, under all conditions, Derjaguin-Landau-Verwey-Overbeek (DLVO) explained well the aggregation kinetic of HAc-MNPs; while extended DLVO (EDLVO) successfully predict that of PAA-MNPs, indicating steric forces among PAA-MNPs. The aggregation of HAc/PAA-MNPs was all inhibited in varied electrolyte solutions by HA (2 mg C/L) addition. This study suggested that carboxyl coatings with higher molecular weights and pKa values could stabilize MNPs better due to stronger electrostatic and additional steric repulsion. However, in the presence of HA, these two forces were mainly controlled by adsorbed HA instead of the organic pre-coatings on MNPs.
A compilation of new advances made in the research field of laboratory reaction kinetics in China's Key Development Project for Air Pollution Formation Mechanism and Control Technologies was presented. These advances are grouped into six broad, interrelated categories, including volatile organic compound (VOC) oxidation, secondary organic aerosol (SOA) formation, new particle formation (NPF) and gas-particle partitioning, ozone chemistry, model parameters, and secondary inorganic aerosol (SIA) formation, highlighting the laboratory work done by Chinese researchers. For smog chamber applications, the current knowledge gained from laboratory studies is reviewed, with emphasis on summarizing the oxidation mechanisms of long-chain alkanes, aromatics, alkenes, aldehydes/ketones in the atmosphere, SOA formation from anthropogenic emission sources, and oxidation of aromatics, isoprene, and limonene, as well as SIA formation. For flow tube applications, atmospheric oxidation mechanisms of toluene and methacrolein, SOA formation from limonene oxidation by ozone, gas-particle partitioning of peroxides, and sulfuric acid-water (H2SO4-H2O) binary nucleation, methanesulfonic acid-water (MSA-H2O) binary nucleation, and sulfuric acid-ammonia-water (H2SO4-NH3-H2O) ternary nucleation are discussed.
In-situ catalytic deNOx is a promising NOx control technology for circulating fluidized bed (CFB) boilers. In this application, matching the conditions between the catalyst and gaseous species is crucial. To understand this, a comprehensive computational particle fluid dynamics (CPFD) model was established; flow, combustion, and NOx emission characteristics in an industrial CFB boiler were elaborated; 20 catalysts with various sizes and densities were designed, and their degree of matching with the gaseous species was evaluated. The simulation results indicated that NOx was gradually produced at the bottom of the furnace and attained its maximum concentration at the elevation of secondary air; CO showed a high concentration in the bottom dense-phase zone; and the homogeneous NO-CO reaction is too weak to effectively reduce NOx. With catalyst application, the NO-CO reaction was evidently enhanced and the in-furnace NOx concentration decreased significantly. The 20 evaluated catalysts can be categorized as dipleg deposition, fluidization circulating, furnace suspension, and furnace deposition types. While the last three types of catalysts could match the spatial and temporal distribution of CO and NOx species well, the furnace suspension-type catalyst produced an optimal matching degree and maximum deNOx efficiency.
Unexpected health shocks may bring catastrophic consequences for households. This paper examines the effect of unexpected adverse health shocks on household members' physical and mental health, labor supply, household income and asset, and health behaviors in China by analyzing two nationally representative datasets and adopting a difference-in-differences method augmented with coarsened exact matching. We find that an unexpected health shock results in a discounted out-of-pocket medical expenditure of 16,943 RMB (US$ 2647) over five years for an average household, a reduction of household income per capita of 841 RMB per year (US$ 131, or 6.0% of household annual income per capita), and a loss of net household asset per capita of 13,635 RMB (US$ 2130, or 9.7% of household asset per capita). It raises the probability of an average household applying for public poverty relief allowance by 2.8 percentage points. In addition, we document a strong intra-household spillover effect of health shocks on mental health and health behaviors. A simple back-of-envelope calculation shows that the health shock induces a private cost of 34,966 RMB (US$ 5463) over 5 years for an average household, and incurs a social financial burden of 6066 RMB (US$ 948) in 5 years per household in medical reimbursement and social welfare transfers. At a national scale, the total social burden of health shocks from cardiovascular and cerebrovascular diseases amounts to 1.1 trillion RMB (US$ 172.1 billion) over 5 years.
Achieving efficient degradation of organic pollutants via activation of sulfite is meaningful but challenging. Herein, we have constructed a heterogeneous catalyst system involving Co3O4 and TiO2 nanoparticles to form the p-n heterojunction (Co3O4/TiO2) to degrade acetaminophen (ACE) through photocatalytic activation of sulfite. Specifically, X-ray photoelectron spectroscopy analysis and theoretical calculations provide compelling evidence of electron transfer from Co3O4 to TiO2 at the heterointerface. The interfacial electron redistribution of Co3O4/TiO2 tunes the adsorption energy of HSO3‒/SO32‒ in sulfite activation process for enhanced the catalytic activity. Owing to its unique heterointerface, the degradation efficiency of ACE reached 96.78% within 10 min. The predominant active radicals were identified as •OH, h+, and SOx•− through radical quenching experiments and electron spin resonance capture. Besides, the possible degradation pathway was deduced by monitoring the generated intermediate products. Thereafter, the enhanced roles of well-engineered compositing interface in photocatalytic activation of sulfite for complete degradation of ACE were unveiled that it can improve light absorption ability, facilitate the generation of active species, and optimize reactive pathways. Considering that sulfite is a waste from flue gas desulfurization process, the photocatalytic activation of sulfite system will open up new avenues of beneficial use of air pollutants for the removal of pharmaceutical wastewater.