Southern Regions Of China Research Articles

Multi-timescale assessment of propagation thresholds from meteorological to hydrological drought

Hydrological drought usually lags behind meteorological drought. Obtaining the propagation threshold (PT) from meteorological drought to hydrological drought is important for providing early warnings of hydrological drought. Previous studies have only used single timescales to characterize PT; however, a single timescale cannot accurately describe the propagation attributes from meteorological to hydrological drought because drought has multi-timescale features. In addition, several methods can be used to obtain PT, such as run theory, correlation analysis, and non-linear response methods. However, these methods might produce different estimates of PT. Here, multi-timescale drought indices, namely the Standardized Precipitation Index (SPI) and Standardized Streamflow Index (SSI), were used to represent meteorological drought and hydrological drought. PT estimates at multiple timescales (e.g., 1-month, 3-month, and 12-month) obtained from run theory, correlation analysis, and non-linear response methods were compared, and the possible reasons for differences in the PT estimates are discussed. We conducted a case study of three sub-basins (Xinfengjiang River, Qiuxiangjiang River, and Andunshui River) with low levels of human activity in the Dongjiang River Basin, which is located in a humid region in southern China. We found that estimates of PT differed at different timescales of drought indices and with different methods at the same timescales. Longer timescales of hydrological drought corresponded to larger PT and vice versa. The major cause of this pattern was the fact that different timescales of drought indices showed different response sensitivities to drought events. The PT obtained from run theory was the shortest; thus, run theory can provide conservative warnings to aid drought prevention and mitigation. Our findings can help drought managers select effective tools to manage the early stages of hydrological drought based on meteorological forecasts and thus minimize the negative impacts of hazards posed by drought.

Effect of Different Rates of Nitrogen Fertilization on Crop Yield, Soil Properties and Leaf Physiological Attributes in Banana Under Subtropical Regions of China.

Excessive nitrogen (N) application is widespread in Southern China. The effects of N fertilization on soil properties and crop physiology are poorly understood in tropical red loam soil. We conducted a field experiment to evaluate the effect of nitrogen fertilization rates on physiological attributes (chlorophyll, plant metabolic enzymes, soluble matters) on banana leaves, soil properties (soil enzymes, soil organic matter (SOM), soil available nutrients) as well as banana crop yield in a subtropical region of southern China. The N rates tested were 0 (N0), 145 (N145), 248 (N248), 352 (N352), 414 (NFT), and 455 (N455) g N per plant. The correlations among soil factors, leaf physiological factors and crop yield were evaluated. The results indiated that the high rates of N fertilization (NFT and N455) significantly decreased soil available potassium (K) content, available phosphorus (P) content, glutamine synthetase (GS) activity, and soluble protein and sugar contents compared with lower N rates. The N352 treatment had the highest crop yields compared with higher N rates treatments, followed by the N455 treatment. However, there were no significant differences in crop yields among N fertilization treatments. Factor analysis showed that the N352 treatment had the highest integrated score for soil and leaf physiological factors among all treatments. Moreover, the N352 treatment was the most effective in improving carbon and nitrogen metabolism in banana. Crop yield was significantly and positively linearly correlated with the integrated score (r = 0.823, p < 0.05). Path analysis revealed that invertase, SOM and sucrose synthase (SS) had a strong positive effect on banana yield. Canonical correspondence analysis (CCA) suggested that available K, invertase, acid phosphatase and available P were the most important factors impacting leaf physiological attributes. Cluster analysis demonstrated distinct differences in N application treatment related to variations in soil and leaf factors. This study suggested that excessive N fertilization had a negative effect on soil fertility, crop physiology and yield. The lower N rates were more effective in improving crop yield than higher rates of N fertilization. The N rate of 352 g N per plant (N352) was recommended to reduce excess N input while maintaining the higher yield for local farmers’ banana planting.

Effect of Deep Vertical Rotary Tillage on Soil Properties and Sugarcane Biomass in Rainfed Dry-Land Regions of Southern China

Conventional tillage (CT) is the main agricultural practice for rainfed sugarcane production in China. However, subsoil compaction formed by long-term CT is harmful to soil properties and crop yield. Deep vertical rotary tillage (DVRT) is a novel tillage practice, which can alleviate subsoil compaction and create a more favorable soil environment for crop growth. This study aims to compare the effects of DVRT and CT practices on soil properties and sugarcane characteristics. The results showed that DVRT reduced soil bulk density and increased soil porosity to some extent in the 0–40 cm soil profile. Soil water storage of DVRT was relatively higher compared with CT due to the combined effects of soil water holding capacity and vegetation water consumption. There was significantly higher final aboveground biomass, underground biomass, and plant height from DVRT compared to CT (p &lt; 0.05), but there were no differences in final root length between tillage practices. Compared with CT, DVRT with one and two growth-years significantly increased aboveground biomass by 68.90% and 50.14%, respectively. Generally, the soil properties and sugarcane characteristics were not significantly different between DVRT with different growth years. DVRT is recommended as a tillage practice for sustainable agriculture in rainfed regions.

Bathing and toileting difficulties of older adults in rural China: the role of environment

BackgroundFor older adults, difficulties in bathing and toileting are often the most prevalent in the index of Activities of daily living (ADL). This study aims to examine how environmental factors are associated with difficulty of bathing and toileting among older adults in rural China.MethodThe data are from the 2014 Thousand-Village Survey (TVS), a national survey of Chinese rural residents of old age. The sample consists of 10,689 subjects, 55 years or older, from 536 villages across all provinces of China. Logistic regressions were applied to examine how difficulty of bathing and toileting was related to environmental factors such as geographic location, neighbourhood amenity, and related facilities of bathing and toileting.ResultsOlder adults living in the Southern regions of China had lesser difficulty in bathing and toileting than those living in Northern China, controlling for other confounders. Better neighbourhood conditions also reduced the likelihood of having such disabilities. Persons who bathed indoors without showering facilities, in public facilities, and outdoors were significantly more likely to have bathing disability than those who showered indoors with facility. Rural older adults who used pedestal pans and indoor buckets for toileting were more likely to have toileting disability than those who used indoor squatting facilities.ConclusionEnvironmental barriers were associated with functional disability among older adults in rural China, but the disabled individuals may change their environments to adapt to their functional capabilities. Our findings suggest that it is imperative to promote the use of showering facilities and pedestal pans for toileting in rural China.

Drainage optimization of paddy field watershed for diffuse phosphorus pollution control and sustainable agricultural development

Rice cultivation consumes abundant irrigation water and fertilizer, which has negative environmental effects. Therefore, water and fertilizer use efficiencies need to be enhanced while ensuring yields, to guarantee sustainable production and reduce diffuse pollution. Paddy rice fields are usually connected with ditches and ponds in the dominant rice planting regions in southern China. However, the influence of drainage optimization on sustainable rice production from source (paddy fields) to process (ditches and ponds) is still unclear. Based on a typical rice cultivation region, a two-year field experiment and a long-term watershed simulation were conducted to evaluate the comprehensive effectiveness of optimizing drainage of paddy field watershed. The results showed that 89.23 % of diffuse P loss from paddy fields via surface runoff occurred during the early growth stages, and particulate P was the main form. Increasing the maximum ponding water level (Hmax) of paddy fields reduced surface runoff without yield loss, and diffuse P loss from paddy fields was decreased by more than 27.18 % after increasing Hmax from 50–80 mm to 60–180 mm at various rice growing stages. In addition, the currently unavoidable diffuse P loss from paddy fields could be effectively intercepted by ditches and ponds. When the Manning’s roughness coefficient of ditch was increased from 0.1 to 0.35, the reduction rate of watershed P loss increased from 1.18 % to 16.02 %, while the reduction rate increased from 10.15 % to 16.52 % when the drainage area of ponds was increased by 50 %. Overall, more rainfall, drainage water and diffuse P can be intercepted by drainage optimization in the paddy field watershed, which would decrease irrigation water requirement and increase fertilizer use efficiency. These results highlight the significant effects of optimizing drainage by increasing the earthen levees of paddy fields to 120–180 mm, maintaining vegetation of ditches, and expanding drainage area of ponds. The proposed measures require more farmers’ labour for maintenance. If extensive implementation can be realised, for example with government's incentive policies, this could represent a big step forward in the effective diffuse pollution control and sustainable agricultural development in China and other rice planting countries.

Carbon sequestration benefits of the grain for Green Program in the hilly red soil region of southern China

Soil erosion disturbs not only the global carbon cycle, but it is a complex environmental problem. Revegetation could reduce carbon emission by controlling soil erosion and increase carbon sequestration and accumulation by fixing carbon in vegetation and soil. The Grain for Green Program (GFGP) of China is the largest ecological restoration program in the world closely related to land-use/land-cover change (LUCC). Systematically assessing the carbon sequestration benefit of GFGP is crucial for a better understanding of the effects of implementing GFGP and providing reasonable vegetation management. Therefore, we selected the hilly red soil region (HRSR) of southern China as a study area, which is one of the main ecologically vulnerable areas in China. We assessed the carbon sequestration in the GFGP area of the HRSR using the InVEST (Integrated Valuation of Environmental Services and Tradeoffs) model based on land-use/land-cover datasets during 2000–2015. Our results show that implementing GFGP is conducive to the enhancement of carbon sequestration services. Total carbon sequestration showed an increasing trend at a rate of 15.43% from 2000 to 2015. The most significant change mainly happened in Hunan Province with the shortest implementation time. The carbon sequestration of each carbon pool (namely aboveground biomass, belowground biomass, soil, and dead organic matter) also increased slightly. Additionally, for carbon sequestration, unused land converted to forest land is the most effective LUCC. This study can provide scientific support for the management and implementation of GFGP in the HRSR of China.

Sequence-Related Amplified Polymorphism (SRAP) Markers Based Genetic Diversity and Population Structure Analysis of Oil Palm (Elaeis guineensis Jacq.)

Oil palm (Elaeis guineensis Jacq.) is the key vegetable oil yielded crop and widely distributed in the southern region of China. The present study aimed at analyzing the genetic diversity and population structure of 223 oil palm accessions collected from four provinces of China by using the sequence-related amplified polymorphism (SRAP) markers. A set of 33 SRAP molecular markers were employed to analyze genetic diversity as well as population structure across 223 oil palm accessions. Out of 514 amplified bands, 487 (94.75%) bands were found to be polymorphic. The PIC value (polymorphic information content) of detected bands was from 0.38 to 0.51, with 0.46 of average. The STRUCTURE analysis categorized the 223 oil palm accessions into three subpopulations. The UPGMA based clustering classified them into three major clusters. The correlation between the population subdivisions and the genetic relationships among oil palm accessions was revealed by UPGMA and Bayesian STRUCTURE analyses. The principal coordinate analysis also confirmed a similar grouping of accessions as revealed by the UPGMA dendrogram and STRUCTURE analysis. AMOVA analysis also revealed the variance of 24% among subpopulations and 76% within subpopulations. The present investigation provided valuable information on population structure and genetic diversity of oil palm populations in China for molecular breeding research in oil palm.

Stable isotope fractionation of cadmium in the soil-rice-human continuum

Consumption of rice (Oryza sativa) grain is a major pathway by which humans are exposed to Cd, especially in non-smoking Asian populations. Although the stable isotope signatures of Cd offer a potential tool for tracing its sources, little is known about the isotopic fractionation of Cd across the entire soil-rice-human continuum. Cadmium isotope ratios were determined in field soils, rice grain, and human urine collected from two Cd-contaminated regions in southern China. Additionally, Cd isotopic fractionation in rice plants was investigated using two transgenic plants differing in Cd uptake and accumulation. Analysis of isotope ratios revealed a preferential enrichment of the heavy Cd isotopes from soil to rice grain (δ114/110Cdgrain-soil = +0.40‰) and from grain to urine (δ114/110Cdurine-grain = +0.40‰) in both regions. The first increase was mainly caused by partitioning between the soil solid phase and the soil solution, with heavier Cd preferentially enriching in the soil solution. Within the rice plant, we identified multiple processes that alter the isotope ratio, but the net effect throughout the plant was comparatively small. Cd fractionation in humans is presumably due to the preferential enrichment of heavier Cd isotopes by metal transporters DMT1 and ZIP8 (responsible for the absorption of Cd into body from the foods). These findings provide important insights into the Cd isotopic fractionation through the soil-rice-human continuum and are helpful for tracing the sources of Cd.

Evaluation of Climatic Condition Suitability for Elderly Care Industry Development in Prefecture-Level Cities in China

The demand for elderly care in China is growing, and the elderly care industry has great development prospects. Climatic conditions are important factors that affect the health of elderly individuals and the development of the elderly care industry. This study will have important guiding significance for the layout of China’s elderly care industry. This paper utilizes ArcGIS and the spatial fuzzy comprehensive evaluation method to analyze the climatic suitability for the development of the elderly care industry in China’s four municipalities, the Hong Kong, Macao, and Taiwan regions, and 333 prefecture-level administrative regions based on six factors: temperature, humidity, airflow, air pressure, sunshine, and precipitation. In addition, development suggestions are proposed. The results show the following. (1) The areas with highly suitable climatic conditions for the development of the elderly care industry in China are concentrated in the eastern and southern areas of Southwest China and the southern areas of Central and East China, mainly in the Yangtze and Pearl River Basins. Slightly suitable areas are distributed around highly suitable areas, concentrated in the central and southern regions of China. Low-suitability areas are clustered, including an area spanning northern North China and East China, southern Northeast China, and central Northwest China, and there is another cluster in Xinjiang. The non-suitable area resembles a strip extending from Northeast China along the Inner Mongolia Plateau to the Qinghai-Tibet Plateau. (2) In Central and Southwest China, there are 57 prefecture-level administrative units with highly suitable temperature conditions that can develop an elderly care industry for patients with cardiovascular and cerebrovascular diseases. Twenty-eight prefecture-level administrative regions with comprehensively suitable temperature and humidity conditions scattered throughout the country can develop an elderly care industry for elderly patients suffering from rheumatic and respiratory diseases.

Biogeographic patterns and co-occurrence networks of diazotrophic and arbuscular mycorrhizal fungal communities in the acidic soil ecosystem of southern China

Low soil nutrient availability severely constrains plant growth and productivity in acidic soil ecosystems. Diazotrophs and arbuscular mycorrhizal fungi (AMF) are the important microbial groups that improve the bioavailability of soil nitrogen (N) and phosphorus (P), respectively. Therefore, the objective was to investigate the biogeographic patterns and co-occurrence networks of the diazotrophic and AMF communities in the acidic soil ecosystem. We collected 52 soil samples from four long-term field observation stations with spatial distances of 961.3 km in the acidic soil region of southern China, and analyzed the community composition and biogeographic distributions of the diazotrophs and AMF using high-throughput sequencing of the functional gene amplicons. The variation partition analysis indicated that soil physicochemical factors provided more contributions than geographic distance, sampling stations and land-use types in the assembly of the diazotrophic and AMF community communities. Distance-decay relationships and Mantel tests showed that soil physicochemical factors had remarkable effects on both microbial community structures, whereas geographic distance only significantly affected the diazotrophic community variations. Co-occurrence network analysis revealed that AMF network was more complex and stable than the diazotrophic network. Furthermore, the dominant genera Bradyrhizbium and Glomus might be the more important keystone taxa in the diazotrophic and AMF networks, respectively. These findings suggest that the diazotrophic and AMF communities exhibit different assembly mechanisms and co-occurrence ecological networks in the acidic soil region of southern China, and both community assemblies were mainly driven by soil physicochemical factors.

Gut Microbiota Changes and Their Relationship with Inflammation in Patients with Acute and Chronic Insomnia.

PurposeThe major purpose of this study was to detect the changes in gut microbiota composition and inflammatory cytokines production associated with acute and chronic insomnia. This study also evaluated the relationship between gut microbiota changes and increased inflammatory cytokines in insomnia patients.Patients and MethodsOutpatients with acute and chronic insomnia (aged 26–55 years; n=20 and 38, respectively) and age/gender-matched healthy controls (n=38) were recruited from a southern China region. Participants’ gut microbiome, plasma cytokines, and self-reported sleep quality and psychopathological symptoms were measured.ResultsThe gut microbiomes of insomnia patients compared with healthy controls were characterized by lower microbial richness and diversity, depletion of anaerobes, and short-chain fatty acid (SCFA)-producing bacteria, and an expansion of potential pathobionts. Lachnospira and Bacteroides were signature bacteria for distinguishing acute insomnia patients from healthy controls, while Faecalibacterium and Blautia were signature bacteria for distinguishing chronic insomnia patients from healthy controls. Acute/chronic insomnia-related signature bacteria also showed correlations with these patients’ self-reported sleep quality and plasma IL-1β.ConclusionThese findings suggest that insomnia symptomology, gut microbiota, and inflammation may be interrelated in complex ways. Gut microbiota may serve as an important indicator for auxiliary diagnosis of insomnia and provide possible new therapeutic targets in the field of sleep disorders.

PHYTOCHEMICAL AND PHARMACOLOGICAL ACTIVITIES OF JUSTICIA PROCUMBENS L.: A REVIEW

Justicia procumbens L. is usually known as water willow which belongs to family Acanthaceae growing widely in southern regions of China, Japan, Vietnam, India and Australia. It is one of the important herbal being used in Ayurvedic system of medicine. The plant contains various active compounds like arylnaphthalide and diarylbutane lignans, glycosides, flavonoids. Few pharmacological properties including anti-inflammatory, anti-arthritic, anti-arrhythmic, anti-asthmatic, anti-proliferative, anti-allergic, antibacterial, cytotoxic and anti-HIV activities activity have been reported for this plant. Conventionally, it is used for the treatment of fever, inflammation, cold, cough, asthma, cancer, snake bites etc. The current review is created with an intended to focus on the numerous ethnobotanical and traditional uses as well as the phytochemical and pharmacological report on Justicia procumbens.

New and little-known bees of the genus Sphecodes Latreille, 1804 (Hymenoptera, Apoidea, Halictidae) from Southern and South-Western China

Continuing prior studies on ChineseSphecodes, we here report further records of twelve rarely collected and little known species from mountainous regions of Southern and South-Western China (Xizang, Sichuan, Yunnan). Forty two species are currently known from China, yet until now only two species were known from Southern and South-Western China. We report six entirely new records for China, includingSphecodes discoverlifeiAstafurova &amp;amp; Proshchalykin, 2020,S. fumipennisSmith, 1853,S. montanusSmith, 1879,S. nipponicusYasumatsu &amp;amp; Hirashima, 1951,S. simlaensisBlüthgen, 1924, andS. turneriCockerell, 1916, and another four are new regional records. Two are new species that we describe and illustrate:Sphecodes holgeriAstafurova &amp;amp; Proshchalykin,sp. nov.(Yunnan), andS. tibeticusAstafurova &amp;amp; Niu,sp. nov.(Xizang). The male ofSphecodes sikkimensisBlüthgen, 1927 is described for the first time.

Multi-time scale variability of rainfall erosivity and erosivity density in the karst region of southern China, 1960–2017

Rainfall erosivity, a measure of the potential for soil erosion by water, is an important factor for estimating soil loss. Understanding the variation tendency of rainfall erosivity is especially critical for soil and water conservation in the fragile ecological environment of the karst region in southern China. This study analysed the rainfall erosivity at multiple spatial and temporal scales based on daily rainfall data observed at 223 meteorological stations during the period of 1960–2017. A daily rainfall erosivity model, co-kring interpolation, regression analysis, gravity model and the Mann-Kendall test were applied in the analysis process. The results indicate the following: (i) The mean annual rainfall erosivity is 5130.00 MJ·mm·ha−1·h−1 in southern China, with a range of 3964.24 to 6425.87 MJ·mm·ha−1·h−1, and varies greatly among different provinces. (ii) The magnitude of rainfall erosivity varies unevenly among seasons, with the mean rainfall erosivity in summer being almost 15 times higher than that in winter. (iii) The annual and seasonal rainfall erosivity has increased in the karst region of southern China over the past 58 years, whereas at the province scale, the seasonal trend in rainfall erosivity is more complex, and the trends are not necessarily linear and positive. Furthermore, at the interdecadal scale, there is no regular trend, and the data exhibit considerable variation. (iv) The temporal variation characteristics of erosivity density are basically consistent with those of rainfall erosivity, and the two show a significant high correlation. (v) The gravity centre of annual rainfall erosivity is located in Tongdao County, while the monthly gravity centre has shifted across Guangxi, Hunan and Guizhou. In summary, knowledge of rainfall erosivity patterns is valuable for assessing the risk of soil erosion and formulating countermeasures.

Reducing ammonia volatilization and increasing nitrogen use efficiency in machine-transplanted rice with side-deep fertilization in a double-cropping rice system in Southern China

Ammonia (NH3) volatilization contributes to major nitrogen (N) fertilizer loss in rice fields. Deep fertilization can effectively mitigate NH3 volatilization and increase N use efficiency (NUE) in agroecosystems. However, the effects of machine-transplanted rice with side-deep fertilization (MRSF) on NUE and NH3 volatilization from paddy fields in double-cropping systems are still unknown. In this study, a field experiment was conducted with double-cropping rice fields in two regions in Southern China (Miluo and Yiyang). NH3 volatilization was measured during the rice growing seasons using the continuous airflow enclosed chamber method under different N application rates with MRSF treatments. The results show that NH3 fluxes in rice soil subjected to different N application rates varied. The ratio of total NH3 loss to applied N by conventional fertilization (CF) ranged from 41.2 to 45.3% in the early-season rice (ESR) and from 44.9 to 45.2% in the late-season rice (LSR). Unlike CF treatment, MRSF treatments significantly reduced the cumulative NH3 loss by approximately 24.8–26.9 % in Miluo and 20.1–20.8 % in Yiyang for ESR and by 18.6–23.0 % in Miluo and 20.2–21.8 % in Yiyang for LSR. MRSF treatments increased the content of available N in the soil by 0.2–8.8 % and 0.7–6.6 % in Miluo and Yiyang, respectively. Moreover, this mitigation effect is expected to be more effective with lower N application rates. An NH3 accumulation model described by the Elovich equation was established over the study period; notably, the field observations fitted the calculated values well. MRSF with a 20–30 % reduction in N application rate yielded a higher NUE in terms of N recovery efficiency (NRE), by 11.5–27.9 % and 11.7–23.7 % in Miluo and 8.2–17.0 % and 7.0–25.8 % in Yiyang relative to that of the CF treatment in ESR and LSR, respectively. Overall, MRSF can reduce the N loss through NH3 volatilization while improving content of available N in the soil and NUE; therefore, further maximizing the yield and simplifying fertilization practices for a cleaner rice production in Southern China.

Evaluating pluvial flood hazard for highly urbanised cities: a case study of the Pearl River Delta Region in China

Rapid urbanisation and economic growth in developing Asian countries have exacerbated their exposure to flood hazards, particularly evident in low-lying urban cities that are currently facing increasing risks from extreme precipitations, likely made worse by the impending climate change. We present a set of simplified indices representative of the characteristics of rainfall-run-off process for evaluating pluvial flood hazard using the fuzzy comprehensive evaluation method. The highly urbanised Pearl River Delta (PRD) region in southern China is studied as an example of mapping the regional pluvial flood hazard and assessing the socio-economic exposure at risk. The developed hazard map captures the broad patterns of high flood hazard zones when compared with reported surface water flooding hotspots and the PRD riverine flood map from the 2015 Global Assessment Report. Further analysis on the regional socio-economic profiles suggests that most PRD cities are faced with large flood loss potential, with estimates of approximate 23 million people and 2.4 trillion RMB gross domestic product exposed to high flood hazard. Mega cities Guangzhou and Shenzhen top the ranking with over 20–40% of their dense urban settlements in the high flood hazard zone. This highlights the impact of human activities on the natural surface run-off process, and the need for robust flood hazard assessment for better understanding and design of holistic solutions towards more adequate flood mitigation systems for continuous urbanisation and future climate conditions.

Establishing forest resilience indicators in the hilly red soil region of southern China from vegetation greenness and landscape metrics using dense Landsat time series

Resilience is the capacity of an ecosystem to respond and recover from damage or stress. It can inherently exhibit the cycle and feedback of the disturbed ecosystem recovery process for a specified period. The current availability of dense and consistent time series of satellite images holds the promise of monitoring forest resilience. The aim of this study is to establish forest resilience indicators using dense Landsat time series and assess forest resilience in response to the maximum disturbance magnitude in the hilly red soil region, Hengyang Basin, Southern China. To achieve this, Landsat images of the study area from 1987 to 2017 were collected. Normalized Difference Vegetation Index (NDVI), i.e., proxy of forest green characteristics, number of patch (NP), average patch size (PS), patch perimeter-area ratio (PPAR) and aggregation index (AI), i.e., proxies of forest landscape metrics were calculated from Landsat images. And then elasticity (i.e., the time and rate of recovery), malleability (i.e., degree of deviation from an initial state) and trend (i.e., the pattern of change) as the indicators of forest resilience were constructed. The local space–time Moran’s I (STI) based on NDVI residual space–time Moran’s I (STI) was employed to characterize the forest disturbance and recovery process. The results revealed the following. Firstly, the STI calculated from dense time series NDVI residuals are successful at monitoring the forest disturbance recovery process, regardless of whether changes were dramatic or subtle. Secondly, the most forest disturbances (i.e., > 75%) occurred in the late 1980s and early 1990s. NDVI and landscape metrics also differed in their response to disturbances; NDVI, PPAR and AI are more malleable to disturbance than PS and NP are. Finally, approximately 40% of the disturbed forest had the strong elasticity with a short recovery time (i.e., a year). We conclude that measuring forest resilience via vegetation greenness and landscape metrics using dense time series satellite images is practical as an operational tool for policy makers, landowners, and national park managers. Moreover, insights into ecological dynamics are emerging from capturing the process showing the difference both before and after the change.

Formation and sink of glyoxal and methylglyoxal in a polluted subtropical environment: observation-based photochemical analysis and impact evaluation

Abstract. The dicarbonyls glyoxal (Gly) and methylglyoxal (Mgly) have been recognized as important precursors of secondary organic aerosols (SOAs) through the atmospheric heterogeneous process. In this study, field measurement was conducted at a receptor site in the Pearl River Delta (PRD) region in southern China, and an observation-based photochemical box model was subsequently applied to investigate the production and evolution of Gly and Mgly as well as their contributions to SOA formation. The model was coupled with a detailed gas-phase oxidation mechanism of volatile organic compounds (VOCs) (i.e., Master Chemical Mechanism, MCM, v3.2), heterogeneous processes of Gly and Mgly (i.e., reversible partitioning in aqueous phase, irreversible volume reactions and irreversible surface uptake processes), and the gas–particle partitioning of oxidation products. The results suggested that without considering the heterogeneous processes of Gly and Mgly on aerosol surfaces, the model would overpredict the mixing ratios of Gly and Mgly by factors of 3.3 and 3.5 compared to the observed levels. The agreement between observation and simulation improved significantly when the irreversible uptake and the reversible partitioning were incorporated into the model, which in total both contributed ∼ 62 % to the destruction of Gly and Mgly during daytime. Further analysis of the photochemical budget of Gly and Mgly showed that the oxidation of aromatics by the OH radical was the major pathway producing Gly and Mgly, followed by degradation of alkynes and alkenes. Furthermore, based on the improved model mechanism, the contributions of VOC oxidation to SOA formed from gas–particle partitioning (SOAgp) and from heterogeneous processes of Gly and Mgly (SOAhet) were also quantified. It was found that o-xylene was the most significant contributor to SOAgp formation (∼ 29 %), while m,p-xylene and toluene made dominant contributions to SOAhet formation. Overall, the heterogeneous processes of Gly and Mgly can explain ∼ 21 % of SOA mass in the PRD region. The results of this study demonstrated the important roles of heterogeneous processes of Gly and Mgly in SOA formation and highlighted the need for a better understanding of the evolution of intermediate oxidation products.

Prevalence and health correlates of anaemia among community-dwelling Chinese older adults: the China Health and Retirement Longitudinal Study

ObjectivesTo identify the prevalence of anaemia among older adults in China by sociodemographic and geographical regions, and cross-sectionally examine the associations between anaemia and several geriatric outcomes.DesignCross-sectional study.Setting and participantsParticipants...

Retrotransposon-based genetic variation and population structure of Impatiens macrovexilla Y. L. Chen in natural habitats and the implications for breeding

Impatiens macrovexilla Y. L. Chen is a potential ornamental herbaceous plant originated from a relatively small area of subtropical Karst region in southern China, and natural populations of this species presented strong adaptability to a range of environmental conditions, with strong horticultural characteristics including bright colour, large flowers, early flowering, long flowering, and floriferousness. Overall, these adventive traits are significant for future selective breeding. Using a ‘jumping gene’ based or retrotransposon-based Inter-Primer Binding Site (iPBS) marker system to evaluate the genetic variation of nine I. macrovexilla populations collected from contrasting environments. The electrophoretic patterns of the PCR products produced for all the accessions were applied to evaluate the genetic diversity and differentiation between populations. The genotyping results distinguished all the 91 individual accessions in nine I. macrovexilla populations from varied microclimates, and population G was separated as a particular variety (I. macrovexilla var. yaoshannensis) which agrees with former botanical classifications about this species. Results from the AMOVA analysis showed that the greatest genetic variation (77 %) was observed within populations whilst 23 % was recorded among populations, indicating a wide range of biotypes at each location where germplasm collected. Results from our PCoA analysis, the phylogenetic dendrogram, and the Bayesian clustering analysis showed obvious subdivision among populations analyzed. The genetic relationships for population G (Jinxiu) and population H (Gantang) were the most different from each other and showed the highest genetic distance of 0.254. Characteristics of specific traits for each population and the genetic relationships of these populations could be utilized in optimizing potential parental candidate for cross combinations. Variations of the genetic pattern and the relationships among and within the populations will impact profoundly on our selective breeding of the species in the future.