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We analyzed multidimensional biodiversity (including species diversity, functional diversity, and phylogenetic diversity) of needle-broadleaf mixed forests of Abies fargesii var. faxoniana-Betula spp. and needleleaf forests of A . fargesii var. faxoniana in the subalpine regions of eastern edge of Qinghai-Tibet Plateau. We measured leaf functional traits including leaf area, leaf thickness, leaf dry matter content, and specific leaf area. The results showed that leaf thickness (0.28 mm) and leaf dry matter content (319.86 mg·g -1 ) in the needle-broadleaf mixed forests were significantly lower than in the needleleaf forest (0.39 mm and 371.33 mg·g -1 , respectively), while specific leaf area (192.74 cm 2 ·g -1 ) was significantly higher (100.91 cm 2 ·g -1 ). Leaf area showed no significant difference between the two forest communities (27.88 and 26.63 cm 2 , respectively). The phylogenetic signals of all leaf functional traits were significant, except for leaf thickness. The phylogenetic structure of the needle-broadleaf mixed forests and needleleaf forest communities tended toward divergence. Shannon diversity index, Simpson diversity index, species richness, functional richness, functional dispersion, Rao's quadratic entropy, and phylogenetic diversity in the needle-broadleaf mixed forests were all significantly higher than in the needleleaf forest, and these indices were significantly positively correlated. Competitive exclusion played a major role in the assembly of subalpine forest communities, and species diversity, functional diversity, and phylogenetic diversity exhibited synchrony.

The natural abundance of stable carbon and nitrogen isotopes (δ 13 C and δ 15 N) in leaves can provide comprehensive information on the physiological and ecological processes of plants and has been widely used in ecological research. However, recent studies on leaf δ 13 C and δ 15 N have focused mainly on woody species, few studies have been conducted on herbs in different vegetation types, and their differences and driving factors are still unclear. In this study, we focused on the herbs in subalpine coniferous forests, alpine shrublands, and alpine mea-dows on the eastern Qinghai-Tibet Plateau, and investigated the differences in leaf δ 13 C and δ 15 N of herbs and the driving factors. The results showed that there were significant differences in leaf δ 13 C and δ 15 N values of herbs among different vegetation types, with the highest δ 13 C and δ 15 N values in alpine meadows, followed by alpine shrublands, and the lowest in subalpine coniferous forests. Using variation partitioning analysis, we revealed that differences in leaf δ 13 C and δ 15 N of herbs among various vegetation types were driven by both leaf functional traits and climate factors, with the contribution of leaf functional traits being relatively higher than that of climate factors. Hierarchical partitioning results indicated that mean annual temperature (MAT), chlorophyll content index, leaf nitrogen content per unit area (N area ), and leaf mass per area were the main drivers of leaf δ 13 C variations of herbs across different vegetation types, while the relative importance of N area and MAT for variation in leaf δ 15 N of herbs was much higher than those other variables. There was a strong coupling relationship between leaf δ 13 C and δ 15 N as indicated by the result of the ordinary least squares regression. Our findings could provide new insights into understanding the key drivers of leaf δ 13 C and δ 15 N variations in herbs across different vegetation types.

As the most senstitive plant organs to environmental changes, leaves serve as crucial indicators of plant survival strategies. We measured the morphology, anatomical traits, gas exchange parameters, and chlorophyll fluorescence parameters of Quercus aquifolioides (evergreen broad-leaved) and Sorbus rehderiana (deciduous broad-leaved) at altitudes of 2600, 2800, 3000, 3200 and 3400 m on the eastern edge of the Qinghai-Tibet Plateau, China. We explored the similarity and difference in their responses to altitude change and the ecological adaptation strategy. The results showed that as the altitude increased, leaf dry matter content of Q. aquifolioides decreased, that of S. rehderiana increased, leaf size for both species gradually decreased, and the palisade coefficient of Q. aquifolioides showed a decreasing trend, contrasting with the increasing trend in S. rehderiana . As the altitude increased, the thickness of leaves, palisade tissue, spongy tissue, upper epidermis, and lower epidermis of both species increased significantly, with the increment of 22.4%, 4.9%, 45.1%, 23.3%, 19.6%, and 28.2%, 46.9%, 8.9%, 25.9%, 20.8% at altitude of 3400 m, respectively, compared with the altitude of 2600 m. The gas exchange and chlorophyll fluorescence parameters of S. rehderiana significantly increased with increasing altitude, while Q. aquifolioides showed the opposite trend. Leaf anatomical traits, gas exchange, and chlorophyll fluorescence parameters of both species displayed considerable plasticity. There were significant correlations among most leaf traits and between leaf traits and altitude. The survival strategy of Q. aquifolioides was more conservative in response to altitude changes, while that of S. rehderiana was more active. Both species adapted to different altitudes by adjusting their own traits.

Exploring the resource limitation of soil microbial metabolism is essential to understand ecosystem functions and processes. However, the spatially divergent patterns and drivers of soil microbial nutrient limitation cha-racteristics in montane ecosystems at small scales, especially at the slope aspect scale, are still unclear. In this study, we measured soil enzyme activities involved in carbon (C), nitrogen (N) and phosphorus (P) cycle and quantified the microbial nutrient limitations by enzyme stoichiometry in two representative mountain sites in subalpine region of western Sichuan, including the sunny and shady slopes with different vegetation types (shrubland and forest, respectively) in Miyaluo of Lixian County, and with the same vegetation type (shrubland) in Yakexia of Heishui County. The results showed that soil enzyme activities and their stoichiometric ratios were significantly different between slope aspects in Miyaluo, while the differences were not significant in Yakexia. The stoichiometry ratio of C-, N- and P-acquiring enzymes on the sunny slope of Miyaluo was 1:0.96:0.92, approaching the 1:1:1 ratio at the global scale, but deviated from 1:1:1 on the shady slope of Miyaluo (1:1.39:0.75) and the different slopes of Yakexia (1:1.09:1.35). There was no significant difference in vector length between slope aspects at both sites, indicating no significant effect of slope aspect on the microbial C limitation. The vector angle was significantly higher on the sunny slope (43.6°) than that on the shady slope (28.7°) in Miyaluo, suggesting that the microorganisms were mainly N-limited. Partial least squares path model showed that the vector angle was mainly directly influenced by the soil nutrient ratios. The vector angle ranged from 50.3° to 51.4°, and did not differ between slope aspects in Yakexia. Therefore, differences in vegetation types between slope aspects drove variations in soil enzyme activity and microbial nutrient limitation through soil properties. It would provide a scientific basis for predicting the spatial pattern of soil enzyme activity and microbial nutrient limitation.

The Qinglong Area of Tianfu New District in China is the connection area of Chengdu city, Sichuan Province, which dominantly supports the primary agricultural products for the metropolis. The soil quality, therefore, has been deteriorating in recent decades due to the intensive planting and industrial pollution. Thus, the evaluation of soil quality and the identification of the pollution sources are significant for sustainable soil planting and regulation. To this end, 395 soil samples were collected, and the parameters of pH, soil organic matter (SOM), total potassium (TK), available potassium (AK), total nitrogen (TN), alkali-hydrolyzable nitrogen (AN), total phosphorus (TP), available phosphorus (AP), Se, B, V, Zn, Mn, Mo, Ni, Co, As, Cd, Cr, Cu, Hg, and Pb were analyzed. The results revealed that TN, Se, Hg, and TP were obviously higher than the background value of the Chengdu Economic Zone, and the Cr, Mn, pH, and TK were depleted. The combination of correlation statistics, geostatistics, and positive matrix factorization (PMF) source analysis revealed that heavy metal enrichments were mainly affected by four sources, namely natural sources (32%)>industrial sources (30%)>agricultural sources (25%)>traffic sources (14%). Likewise, the source apportionments were verified regarding topography, industrial boundary, farmer density, and traffic flow. It was estimated that Mo, Co, Ni, and V were affected by slope; the enrichment of Hg and As was the result of agricultural activities; Cd, Mn, Cr, and Zn were affected by industrial waste diffusion; and Pb, Zn, Cu, Cd, and Hg were related to transportation. To a certain extent, agricultural fertilization and pesticide application have partially controlled soil fertility and pollution (Hg and As).

Objectives: This study aimed to evaluate associations between mental distress and COVID-19-related changes in behavioral outcomes and potential modifiers (age, gender, educational attainment) of such associations., Study Design: This was a cross-sectional study., Methods: An online survey using anonymous network sampling was conducted in China from April to May 2020 using a 74-item questionnaire. A national sample of 10,545 adults in 31 provinces provided data on sociodemographic characteristics, COVID-19-related mental distress, and changes in behavioral outcomes. Structural equation models were used for data analyses., Results: After adjusting for covariates, greater mental distress was associated with increased smoking (odds ratio [OR] = 1.42, 95% confidence interval [CI]: 1.20-1.68 and OR = 1.54, 95% CI: 1.31-1.82 per one standard deviation [SD] increase in mental distress) and alcohol consumption (OR = 1.67, 95% CI: 1.45-1.92 and OR = 1.47, 95% CI: 1.24-1.75 per one SD increase in mental distress) among current smokers and drinkers and with both increased and decreased physical activity (ORs ranged from 1.32 to 1.56). Underweight adults were more likely to lose body weight (≥1 kg; OR = 1.63, 95% CI: 1.30-2.04), whereas overweight adults were more likely to gain weight (OR = 1.61, 95% CI: 1.46-1.78) by the same amount. Association between mental distress and change in physical activity was stronger in adults aged ≥40 years (ORs ranged from 1.43 to 2.05) and those with high education (ORs ranged from 1.43 to 1.77). Mental distress was associated with increased smoking in males (OR = 1.60, 95% CI: 1.37-1.87) but not females (OR = 1.11, 95% CI: 0.82-1.51)., Conclusions: Greater mental distress was associated with some positive and negative changes in behavioral outcomes during the pandemic. These findings inform the design of tailored public health interventions aimed to mitigate long-term negative consequences of mental distress on outcomes., (Copyright © 2021 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.)

Objective: China launched its health reform in 2009. This study aimed to assess changes in preventive care utilisation (PCU) and its relationship with the healthcare reform., Design: A cross-sectional study using demographic characteristics, socioeconomic status, environmental factors, and lifestyle and health status data of adults from five waves (2004-2015) of the China Health and Nutrition Survey (CHNS) was conducted. Multilevel mixed-effects logistic regression models were used., Setting: Data were derived from urban and rural communities of nine provinces in China., Participants: Data were obtained from five waves of the CHNS, with 9960 participants in 2004, 9888 in 2006, 10 286 in 2009, 9709 in 2011, and 10 628 in 2015., Outcome: The primary outcome was PCU., Results: PCU in 2004-2015 among adults was 3.29%, 3.13%, 3.77%, 4.95% and 2.73%, respectively. Whether before or after the health reform, having a history of disease and female gender were positive influencing factors of PCU. Before 2009, PCU was significantly associated with gender, income, medical insurance status and region. Age, medical insurance status, history of drinking and education level significantly affected PCU in 2009-2011. Having medical insurance was no longer a positive influencing factor of PCU, while high income had a negative effect on PCU, in 2011-2015., Conclusions: PCU from 2004 to 2015 was low and the health reform in China may lack sustainable effect on PCU. Further studies on how to ensure sustainability of PCU are necessary, and further reforms on preventive care services should be aimed at different ages, rural areas and participants without history of disease., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: To discuss the methods and clinical outcomes of selective tarsometatarsal (TMT) arthrodesis for old Lisfranc injury. Methods: The clinical data of 36 cases with old Lisfranc injury treated by selective arthrodesis from January 2010 to October 2016 in the Department of Orthopedics in Shanghai Sixth People's Hospital were analyzed retrospectively. There were 16 males and 20 females in this group with a mean age of (40±6) years. The information of pre-operative and post-operative X-ray, American Orthopaedics Foot and Ankle Society (AOFAS) midfoot score and pain Visual Analogue Scale (VAS) score was collected. The complications were also recorded. The pre- and post-operative data were compared with t test. Results: The 36 patients got a follow-up for at-least 2 years (averaged (4.3±1.6) years, ranged from 2 to 8 years). The post-operative AOFAS midfoot score was improved from (44±7)(28-60) to (83±7)(76-97)( t= -37.1, P< 0.05), and the VAS score decreased from (6.3±2.5)(5-9) to (1.6±1.3)(0-3)( t= 23.7, P< 0.05). Implant breakage occurred in two patients and the symptom was relieved after the removal of implants. Conclusion: The selective TMT arthrodesis for old Lisfranc injury may relieve the symptoms, improve the function and life quality of patients by restoring the medial arch and midfoot and forefoot alignment.

To better understand the response and adaptation of plants to altitudinal changes, four sites at the altitude of 2200 m, 2500 m, 3100 m and 3400 m on Balang Mountain were selected to test and calculate the eco-physiological parameters in leaves of Betula utilis, including photosynthetic nitrogen use efficiency (PNUE), CO 2 diffusion conductance (stomatal conductance g s and mesophyll conductance g m ) and nitrogen allocation in each component (fractions of leaf nitrogen allocated to Rubisco P R , to bioenergetics P B , to light-harvesting components P L , and to cell wall P CW ). Their changes with altitudinal variations and the relationships between leaf PNUE and the other parameters were analyzed. The results showed that PNUE, P R , and P B of the leaves were relatively higher at 2500 m and 3100 m. With the increases of altitude, g s and g m increased and P L decreased. The correlations between P R , P B and PNUE were significant, indicating that P R and P B were the main factors driving the changes in leaf PNUE in response to altitudinal variations. Besides, the fraction of leaf nitrogen allocated to photosynthetic apparatus (P P ) was relatively higher at 2500 m and 3100 m. With increasing altitude, P CW decreased and the fraction of leaf nitrogen allocated to the other components (P other ) increased, which suggested that B. utilis leaves tended to allocate more nitrogen to the other components instead of the photosynthetic apparatus and cell wall with the increasing altitude to well adapt environmental changes.

Objective: To investigate the Z scores for growth and development, physical fitness, and the relationship between them in preschool children in Yantai City, China, and to provide scientific evidence for health care in children., Methods: A total of 362 children aged 3 to 4 years, whose data were recorded in the National Physical Fitness Survey in Yantai in 2010, were included in the study. Z scores for weight-for-age, height-for-age and body mass index-for-age were calculated. The relationship between Z scores and physical fitness was determined by Pearson's correlation analysis., Results: The mean Z scores were all positive numbers. The prevalence rates of underweight and growth retardation were very low, but that of obesity was relatively high (up to 16.5% in 4-year-old boys). There were differences in physical fitness between children of different ages and between boys and girls (P<0.05). The Z scores showed correlation with some physical fitness indices (P<0.05), but they were not closely correlated as the value of r was not more than 0.30., Conclusions: Z scores for growth and development remain at relatively high levels in preschool children in Yantai. The physical fitness is associated with age and gender in these children. There are weak correlations between Z scores and some physical fitness indices. Effective measures should be taken to adjust dietary habits and promote exercise for children, thus preventing obesity and improving physical fitness.

The concentrations of hexachlorocyclohexane (HCHs), dichlorodiphenyltrichloroethane (DDTs), and polybrominated diphenyl ethers (PBDEs) in muscle, liver and brain of ducks from Baiyangdian Lake were determined by gas chromatography coupled with mass spectrometer (GC/MS). The results showed that the concentrations of HCHs, DDTs and PBDEs in various tissues of ducks were in the range of 0.9-5.0 ng/g wet weight (WW), 0.3-2.8 ng/g (WW) and 0.03-0.65 ng/g (WW), respectively. Statistical analysis indicated that the accumulation of DDTs and PBDEs in muscle, liver and brain was significantly different (p < 0.05), but not with HCHs (p > 0.05). Liver tissues contained the highest DDTs and PBDEs levels, with average concentrations of 2.3 ng/g (WW) and 0.37 ng/g (WW), respectively. Among the HCH isomers and DDT metabolites, beta-HCH was the predominant isomers in liver and brain tissues, and p,p'-DDE was the dominant metabolites of DDTs in various tissues. Among the PBDE congeners, BDE47 and BDE99 were the predominant in various tissues. The different profiles of persistent organohalogen compounds in various tissues of ducks may reflect that the Baiyangdian Lake still subject to the contamination of historically residue for HCHs and DDTs. In addition, the source of PBDEs was partly attributed to the industrial pollution, chemical plants, and sewage discharging.

Based on the investigation in a 4 hm2 Betula-Abies forest plot in sub-alpine area in West Sichuan of China, and by using point pattern analysis method in terms of O-ring statistics, the spatial patterns of dominant species Betula albo-sinensis and Abies faxoniana in different age classes in study area were analyzed, and the intra- and inter-species associations between these age classes were studied. B. albo-sinensis had a unimodal distribution of its DBH frequency, indicating a declining population, while A. faxoniana had a reverse J-shaped pattern, showing an increasing population. All the big trees of B. albo-sinensis and A. faxoniana were spatially in random at all scales, while the medium age and small trees were spatially clumped at small scales and tended to be randomly or evenly distributed with increasing spatial scale. The maximum aggregation degree decreased with increasing age class. Spatial association mainly occurred at small scales. A. faxoniana generally showed positive intra-specific association, while B. albo-sinensis generally showed negative intra-specific association. For the two populations, big and small trees had no significant spatial association, but middle age trees had negative spatial association. Negative inter-specific associations of the two populations were commonly found in different age classes. The larger the difference of age class, the stronger the negative inter-specific association.

Background: The intake of iron is positively related to the risk of diabetes, whilst magnesium intake is inversely related. However, it is unknown whether there is an interaction between dietary magnesium and iron expressed as a ratio and diabetes., Methods: This is a cross-sectional household survey carried out in 2002 in Jiangsu Province, China. A total of 2849 men and women aged >or = 20 years participated (participation rate 89.0%). Iron and magnesium intake was assessed by 3-day weighed food records. Fasting plasma glucose, serum ferritin and haemoglobin were measured., Results: The mean intake of iron and magnesium was 25 mg/day and 332 mg/day, respectively. The prevalence of diabetes was 3.0% in men and 2.6% in women. Magnesium intake was negatively associated with diabetes when adjusted for age and sex, but not in a fully adjusted model. A strong inverse association between magnesium : iron intake ratio and diabetes was observed. In the fully adjusted model, the odds ratios of diabetes across quartiles of magnesium : iron intake ratio were: 1.0, 0.63 [95% confidence interval 0.32-1.25], 0.36 (0.16-0.81) and 0.48 (0.20-1.14) (P for trend 0.038). There was an interaction between central obesity and magnesium : iron ratio., Conclusion: Magnesium : iron intake ratio is an independent risk marker for diabetes in Chinese adults. As this is a cross-sectional study, we cannot establish any causal relationship.

No single hypothesis or theory has been widely accepted for explaining the functional mechanism of global alpine/arctic treeline formation. The present study tested whether the alpine treeline is determined by (1) the needle nitrogen content associated with photosynthesis (carbon gain); (2) a sufficient source-sink ratio of carbon; or (3) a sufficient C-N ratio. Nitrogen does not limit the growth and development of trees studied at the Himalayan treelines. Levels of non-structural carbohydrates (NSC) in trees were species-specific and site-dependent; therefore, the treeline cases studied did not show consistent evidence of source/carbon limitation or sink/growth limitation in treeline trees. However, results of the combined three treelines showed that the treeline trees may suffer from a winter carbon shortage. The source capacity and the sink capacity of a tree influence its tissue NSC concentrations and the carbon balance; therefore, we suggest that the persistence and development of treeline trees in a harsh alpine environment may require a minimum level of the total NSC concentration, a sufficiently high sugar:starch ratio, and a balanced carbon source-sink relationship.

By adopting space as a substitute for time, and based on the approaches of inter-specific association, PCA and optimal division, the restoration stages of various secondary forest communities originated from the natural succession processes of bamboo-dark brown coniferous and moss-dark brown coniferous old-growth forests after clear-cut were quantified at different temporal series (20, 30, 30, 40, 50 and 160-200 years). The results showed that Betula albo-sinensis, Salix rehderiana, Acer mono, A. laxiflorum, Prunus tatsienensis, Hydrangea xanthoneura, Tilia chinensis and Salix dolia were the declining species groups with progressive restoration processes from secondary forest to mature moss and bamboo-dark brown coniferous forests, Sorbus hupehensis, S. koehneana and P. pilosiuscula were the transient species groups, and Abies faxoniana, Picea purpurea, Tsuga chinensis and P. wilsonii were the progressive species groups. During the period of 20-40 years restoration, the secondary forests were dominated by broad-leaved tree species, such as B. albo-sinensis, and the main forest types were moss--B. albo-sinensis forest and bamboo--B. albo-sinensis forest. Through 50 years natural succession, the secondary forests turned into conifer/broad-leaved mixed forest dominated by B. albo-sinensis and A. faxoniana, and the main forest types were moss--B. albo-sinensis--A. faxoniana forest and bamboo--B. albo-sinensis--A. faxoniana forest. The remained 160-200 years old coniferous forests without cutting were dominated by old-growth stage A. faxoniana, and the main forest types were moss--A. faxoniana forest and bamboo--A. faxoniana forest.