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Aphis glycines Matsumura is an important pest of soybean in Asia and North America. Hymenoptera parasitoids play a key role in the control of the soybean aphid. The correct identification of parasitoids is a critical step that precedes the assessment of their potential biological control agents. Accurate identification of the majority of the species attacking the soybean aphid often requires elaborate specimen preparation and expert taxonomic knowledge. In this study, we facilitated the identification of soybean aphid parasitoids by applying a DNA barcoding approach following a preliminary morphological identification. We generated DNA sequence data from the mitochondrial COI gene and the D2 region of 28S rDNA to assess the genetic variation within and between parasitoid species emerging from the soybean aphid in China. Fifteen Hymenoptera parasitoid species belonging to 10 genera of five families were identified with little intra-specific variation (0.09% ± 0.06% for 28S and 0.36% ± 0.18% for COI) and large inter-specific divergence (30.46% ± 3.42% for 28S and 20.4% ± 1.20% for COI). [ABSTRACT FROM AUTHOR]

Soil carbon sequestration was estimated in a conifer forest and an alpine meadow on the Tibetan Plateau using a carbon-14 radioactive label provided by thermonuclear weapon tests (known as bomb-14C). Soil organic matter was physically separated into light and heavy fractions. The concentration spike of bomb-14C occurred at a soil depth of 4 cm in both the forest soil and the alpine meadow soil. Based on the depth of the bomb-14C spike, the carbon sequestration rate was determined to be 38.5 g C/m2 per year for the forest soil and 27.1 g C/m2 per year for the alpine meadow soil. Considering that more than 60% of soil organic carbon (SOC) is stored in the heavy fraction and the large area of alpine forests and meadows on the Tibetan Plateau, these alpine ecosystems might partially contribute to “the missing carbon sink”. [ABSTRACT FROM AUTHOR]

This paper evaluated the MODerate resolution Imaging Spectroradiometer (MODIS) gross primary production (GPP) product (MOD17) by using estimated GPP from eddy-covariance flux measurements over an irrigated winter wheat and maize double-cropping field on the North China Plain in 2003–2004, and an alpine meadow on the Tibetan Plateau in 2002–2003. The mean annual GPP from MOD17 accounted for 1/2–2/3 of the surface estimated mean annual GPP for the alpine meadow, but only about 1/5–1/3 for the cropland. This underestimation was partly attributed to low estimates of leaf area index by a MODIS product (MOD15) because it is used to calculate absorbed photosynthetically active radiation in the MOD17 algorithm. The main reason is that the parameter maximum light use efficiency ( εmax) in the MOD17 algorithm was underestimated for the two biomes, especially for the cropland. Contrasted to the default, εmax was optimized using surface measurements. The optimized εmax for winter wheat, maize and meadow was 1.18, 1.81 and 0.73 g C/MJ, respectively. By using the surface measurements and optimized εmax , the MOD17 algorithm significantly improved the accuracy of GPP estimates. The optimum MOD17 algorithm explained about 82%, 68%, and 79% of GPP variance for winter wheat, maize, and meadow, respectively. These results suggest that it is necessary to adjust the MOD17 parameters for the estimation of cropland and meadow GPP, particularly over cropland. [ABSTRACT FROM AUTHOR]

Biodiversity can stabilise productivity through different mechanisms, such as asynchronous species responses to environmental variability and species stability. Global changes, like intensified drought, could negatively affect species richness, species asynchrony and species stability, but it is unclear how changes in these mechanisms will affect the stability of above‐ground primary productivity (ANPP) across ecosystems.We studied the effects of a 4‐year extreme drought on ANPP stability and the underlying mechanisms (species richness, species asynchrony and species stability) across six grasslands in Northern China. We also assessed the relative importance of these mechanisms in determining ANPP stability under extreme drought.We found that extreme drought decreased ANPP stability, species richness, species asynchrony and species stability across the six grasslands. However, structural equation modelling revealed that species asynchrony, not species richness or species stability, was the most important mechanism promoting stability of ANPP, regardless of drought across the six grasslands.Synthesis. Our results suggest that species asynchrony, not species richness and species stability, consistently buffers ecosystem stability against extreme drought across and within grasslands spanning a broad precipitation gradient. Thus, species asynchrony may be a more general mechanism for promoting stability of ANPP in grasslands in the face of intensified drought. [ABSTRACT FROM AUTHOR]

Grasslands are subject to climate change, such as severe drought, and an important aspect of their functioning is temporal stability in response to extreme climate events. Previous research has explored the impacts of extreme drought and post‐drought periods on grassland stability, yet the mechanistic pathways behind these changes have rarely been studied.Here, we implemented an experiment with 4 years of drought and 3 years of recovery to assess the effects of drought and post‐drought on the temporal stability of above‐ground net primary productivity (ANPP) and its underlying mechanisms. To do so, we measured community‐weighted mean (CWM) of six plant growth and nine seed traits, functional diversity, population stability and species asynchrony across two cold, semiarid grasslands in northern China. We also performed piecewise structural equation models (SEMs) to assess the relationships between ANPP stability and its underlying mechanisms and how drought and post‐drought periods alter the relative contribution of these mechanisms to ANPP stability.We found that temporal stability of ANPP was not reduced during drought due to grasses maintaining productivity, which compensated for increased variation of forb productivity. Moreover, ANPP recovered rapidly after drought, and both grasses and forbs contributed to community stability during the post‐drought period. Overall, ANPP stability decreased during the combined drought and post‐drought periods because of rapid changes in ANPP from drought to post‐drought. SEMs revealed that the temporal stability of ANPP during drought and post‐drought periods was modulated by functional diversity and community‐weighted mean traits directly and indirectly by altering species asynchrony and population stability. Specifically, the temporal stability of ANPP was positively correlated with functional divergence of plant communities. CWMs of seed traits (e.g. seed width and thickness), rather than plant growth traits (e.g. specific leaf area and leaf nutrient content), stabilized grassland ANPP. Productivity of plant communities with large and thick seeds was less sensitive to precipitation changes over time.These results emphasize the importance of considering both the functional trait distribution among species and seed traits of dominant species since their combined effects can stabilize ecosystem functions under global climate change scenarios. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Asexual reproduction plays a fundamental role in the structure, dynamics and persistence of perennial grasslands. Thus, assessing how asexual reproductive traits of plant communities respond to drought may be key for understanding grassland resistance to drought and recovery following drought.Here, we quantified three asexual reproductive traits (i.e. above‐ground tiller abundance, below‐ground bud abundance and the ratio of tillers to buds) during a 4‐year severe drought and a 2‐year drought recovery period in four grasslands that spanned an aridity gradient in northern China. We also assessed the relationship between these traits and the resistance and recovery of above‐ground net primary productivity (ANPP).We found that drought had limited and largely inconsistent effects on asexual reproduction among drought and recovery years and grasslands overall. Drought increased tiller abundance in the first treatment year and reduced bud banks by the fourth treatment year across grasslands. However, neither of the three asexual reproductive traits were correlated with drought resistance of ANPP. Drought legacies differed among the four grasslands with positive, negative and no legacies evident for the three asexual reproductive traits, and no clear relationship with aridity. Bud banks and tiller to bud ratio decreased and increased, respectively, in the first recovery year, but not in the second recovery year. In contrast to drought resistance, community bud abundance was strongly related to recovery, such that communities with higher bud abundance had greater ANPP recovery following drought.Synthesis. These results suggest that asexual reproductive traits may be important drivers of ecosystem recovery after drought, but that variable responses of these asexual reproduction traits during drought complicates predictions of overall grassland responses. [ABSTRACT FROM AUTHOR]

Grasslands are expected to experience droughts of unprecedented frequency and magnitude in the future. Characterizing grassland responses and recovery from drought is therefore critical to predict the vulnerability of grassland ecosystems to climate change. Most previous studies have focused on ecosystem responses during drought while investigations of post‐drought recovery are rare. Few studies have used functional traits, and in particular bud or clonal traits, to explore the mechanisms underlying grassland responses to and recovery from drought.To address this issue, we experimentally imposed a four‐year drought in a C3‐dominated grassland in northeastern China and monitored recovery for 3 years post‐drought. We investigated the immediate and legacy effects of drought on total above‐ground net primary productivity (ANPP), ANPP of functional groups (rhizomatous grasses, bunch grasses and forbs), and how the legacy effects were driven by plant species diversity, clonal traits and vegetative traits.We found that drought progressively reduced total ANPP over the 4‐year period. The reductions in total ANPP in the first and third drought years were caused by the decrease in ANPP of bunch grasses only, while that of the second year was caused by declines in ANPP of bunch grasses and forbs, and the fourth year decline was linked to all three functional groups. The post‐drought recovery of ANPP, which occurred despite the continued loss of plant species diversity, was mainly driven by rapid recovery of rhizomatous and bunch grasses, which compensated for the slow response by forbs. The rapid post‐drought recovery of these grasses can be attributed to their relatively large, intact bud and shoot densities post‐drought, as well as the recovery of plant height and specific leaf area. The rapid recovery of grasses possibly restricted the growth and distribution of forbs, resulting in reduced forb ANPP and, consequently, lower species diversity during the recovery period.Synthesis. These results highlight the potential for positive legacy effects of drought on ANPP as well as the important and complementary roles of plant reproductive and vegetative traits in mediating ecosystem recovery from drought in a C3‐dominated grassland. [ABSTRACT FROM AUTHOR]

Climate change is expected to increase the magnitude and frequency of extreme drought in most grassland ecosystems. Exploring the responses of below‐ground bud banks and their relationships with above‐ground plant structure and drought is need to explain how climate change will impact grassland ecosystems. However, studies on the response of community‐scale bud and shoot densities to experimental drought along an aridity gradient are rare.We experimentally removed 66% of growing season precipitation for 4 years in three temperate grasslands that spanned an aridity gradient in northern China. We quantified the legacy effects of drought on grass, forb and total community below‐ground bud density, above‐ground shoot density and the ratio of bud to shoot density 1 year following treatment.Below‐ground bud density was lowest at the highest aridity site for the entire community, while above‐ground shoot density was highest at the medium aridity site. Below‐ground bud and above‐ground shoot densities were the lowest at the high aridity site for grasses but the highest for forbs at this site. Bud:shoot ratios decreased with increasing aridity for grasses, yet remained constant for forbs along the aridity gradient. Below‐ground bud density in drought plots remained lower than controls a year following drought at each site. Experimental drought did not alter the below‐ground bud bank for grasses but decreased forb bud banks across sites. Experimental drought had little legacy effects on above‐ground shoot density and bud:shoot ratios for grasses, forbs and the total community at each site.Our results suggest that grass and forb bud banks can differ in their responses to both multi‐year drought along an aridity gradient, and that bud limitation for shoot generation may increase as grasslands get drier. Bud bank responses to climate will impact plant community functioning and resilience. Thus, incorporating bud bank dynamics will improve projections of grassland ecosystems under future climate change. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Plant traits are useful proxies of plant strategies and can influence community and ecosystem responses to climate extremes, such as severe drought. Few studies, however, have investigated both the immediate and lagged effects of drought on community‐weighted mean (CWM) plant traits, with even less research on the relative roles of interspecific vs. intraspecific trait variability in such responses.We experimentally reduced growing season precipitation by 66% in two cold‐semi‐arid grassland sites in northern China for four consecutive years to explore the drought resistance of CWM traits as well as their recovery 2 years following the drought. In addition, we isolated the effects of both interspecific and intraspecific trait variability on shifts in CWM traits.At both sites, we observed significant effects of drought on interspecific and intraspecific trait variability which, in some cases, led to significant changes in CWM traits. For example, drought led to reduced CWM plant height and leaf phosphorous content, but increased leaf carbon content at both sites, with responses primarily due to intraspecific trait shifts. Surprisingly, these CWM traits recovered completely 2 years after the extreme drought. Intraspecific trait variability influenced CWM traits via both positive and negative covariation with interspecific trait variability during drought and recovery phases.These findings highlight the important role of interspecific and intraspecific trait variability in driving the response and recovery of CWM traits following extreme, prolonged drought. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Seeds provide the basis of genetic diversity in perennial grassland communities and their traits may influence ecosystem resistance to extreme drought. However, we know little about how drought effects the community functional composition of seed traits and the corresponding implications for ecosystem resistance to drought.We experimentally removed 66% of growing season precipitation for 4 years across five arid and semi‐arid grasslands in northern China and assessed how this multi‐year drought impacted community‐weighted means (CWMs) of seed traits, seed trait functional diversity and above‐ground net primary productivity (ANPP).Experimental drought had limited effects on CWM traits and the few effects that did occur varied by site and year. For three separate sites, and in different years, drought reduced seed length and phosphorus content but increased both seed and seed‐coat thickness. Additionally, drought led to increased seed functional evenness, divergence, dispersion and richness, but only in some sites, and mostly in later years following cumulative effects of water limitation. However, we observed a strong negative relationship between drought‐induced reductions in ANPP and CWMs of seed‐coat thickness, indicating that a high abundance of dominant species with thick seeds may increase ecosystem resistance to drought. Seed trait functional diversity was not significantly predictive of ANPP, providing little evidence for a diversity effect.Our results suggest that monitoring community composition with a focus on seed traits may provide a valuable indicator of ecosystem resistance to future droughts despite inconsistent responses of seed trait composition overall. This highlights the importance of developing a comprehensive seed and reproductive traits database for arid and semi‐arid grassland biomes. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The present investigation is the first to provide information on the formation, process and influence factors for hydrocarbon generation and expulsion potential of the Cuizhuang Formation source rock in the Yuncheng sub‐basin to decipher the reason why no commercial petroleum resources have been found so far. In this study, data from the Jitan‐1 well in the Yuncheng sub‐basin were applied for the Cuizhuang Formation source rock basin modelling and organic geochemical analyses to reconstruct the burial and thermal evolution history and reveal the timing and process of hydrocarbon generation and expulsion. The modelling results indicate that the peak palaeotemperature of the Cuizhuang Formation source rock reached ~205°C in the Middle Carboniferous (~327 Ma) at a maximum burial depth of ~4000 m, when rapid burial subsidence and thermal events played a significant role in increasing thermal maturity. The Cuizhuang Formation generated and expelled small amounts of hydrocarbons from the Early Ordovician until the Middle Carboniferous, starting with the primary kerogen cracking and conversion to oil from the Early to Middle Ordovician (~476–461 Ma), corresponding to the thermal maturity values of 0.55–0.70 %VRo and transformation ratio (TR) <10%. The expulsion of most generated oil (0.70–1.30 %VRo, TR of 10%–90%) started from the Middle Ordovician to the Early Carboniferous (~461–351 Ma), before reaching the secondary cracking of the retained oil into gas (>1.30 %VRo and TR of 90%–100%) from the Early to Middle Carboniferous (~351–327 Ma). Destruction of the initial formation of hydrocarbon reservoirs in the Yuncheng sub‐basin was primarily controlled by the Middle Carboniferous tectonic event with its major uplift‐erosion, resulting in the absence of potential hydrocarbon reservoirs in recent exploration activities in some parts of the Yuncheng sub‐basin. [ABSTRACT FROM AUTHOR]

Aim: Transarterial chemoembolization (TACE) combined with a PD‐1 inhibitor and TACE combined with a PD‐1 inhibitor and lenvatinib have recently been reported as promising treatments to improve the prognosis of hepatocellular carcinoma (HCC) patients. This study aims to compare the efficacy of these two treatments. Methods: A retrospective study was conducted, and patients were recruited from two centers in China. Progression‐free survival (PFS) and overall survival (OS) were compared, and the objective response rate (ORR) and disease control rate (DCR) were evaluated according to the modified Response Evaluation Criteria in Solid Tumors (mRECIST). Treatment‐related adverse events (AEs) were analyzed to assess safety. Results: The median follow‐up for the entire cohort was 11.4 months. Of the 103 patients included in this study, 56 received triple therapy, and 47 received doublet therapy. PFS was significantly higher in the triple therapy group than in the doublet therapy group (mPFS 22.5 vs. 14.0 months, P < 0.001). Similar results were obtained in terms of OS (P = 0.001). The ORR and DCR were also better in the triple therapy group (64.3% vs. 38.3%, P = 0.010; 85.7% vs. 57.4%, P = 0.002). The most common AEs in the triple therapy group were decreased albumin (55.3%), decreased platelet count (51.8%) and hypertension (44.6%). Conclusions: The combination of TACE with a PD‐1 inhibitor and lenvatinib in patients with BCLC stage B HCC might result in significantly improved clinical outcomes with a manageable safety profile compared with TACE with a PD‐1 inhibitor. [ABSTRACT FROM AUTHOR]

Background and Aim: The aim of this study was to investigate the influence of polygenetic polymorphisms, which play a role in the pathogenesis of metabolic syndrome, on the susceptibility to non-alcoholic fatty liver disease (NAFLD) of Chinese people. Methods: The subjects were selected from an epidemiological survey in the Guangdong province of southern China. In each polymorphism study, 50–117 subjects who met the diagnostic criteria of NAFLD and had typical clinical and ultrasonographic findings were placed into the case group. Using a nested case–control design, the same numbers of matched people without NAFLD were included as controls. Single nucleotide polymorphisms (SNP) at nine positions in seven candidate genes were tested. These SNP were found to be associated with the pathogenesis of metabolic syndrome. Genetic analyses were performed using genomic DNA extracted from peripheral blood leukocytes. Polymerase chain reaction–restriction fragment length polymorphism was applied to detect SNP. Results: Most candidate genes' SNP were associated with susceptibility to NAFLD. Some showed positive relationships (increased risk): tumor necrosis factor-α-238, adiponectin-45, leptin-2548, peroxisome proliferator-activated receptors-161 and phosphatidyletha-nolamine N-methyltransferase-175. Other SNP demonstrated a negative association (decreased risk): adiponectin-276 and hepatic lipase-514. Only two were not associated: tumor necrosis factor-α-380 and peroxisome proliferator-activated receptors-γ co-activator-1α-482. Conclusion: Most candidate genes' SNP examined in metabolic syndrome patients were associated with susceptibility to NAFLD. [ABSTRACT FROM AUTHOR]

Summary: The Chinese jujube (Ziziphus jujuba Mill.), a member of the Rhamnaceae family, is an important perennial fruit tree crop of substantial economic, ecological and nutritional value, and is also used as a traditional herbal medicine. Here, we report the resequencing of 493 jujube accessions, including 202 wild and 291 cultivated accessions at >16× depth. Our population genomic analyses revealed that the Shanxi–Shaanxi area of China was jujube's primary domestication centre and that jujube was then disseminated into East China before finally extending into South China. Divergence events analysis indicated that Ziziphus acidojujuba and Ziziphus jujuba diverged around 2.7 Mya, suggesting the interesting possibility that a long pre‐domestication period may have occurred prior to human intervention. Using the large genetic polymorphism data set, we identified a 15‐bp tandem insertion in the promoter of the jujube ortholog of the POLLEN DEFECTIVE IN GUIDANCE 1 (POD1) gene, which was strongly associated with seed‐setting rate. Integrating genome‐wide association study (GWAS), transcriptome data, expression analysis and transgenic validation in tomato, we identified a DA3/UBIQUITIN‐SPECIFIC PROTEASE 14 (UBP14) ortholog, which negatively regulate fruit weight in jujube. We also identified candidate genes, which have likely influenced the selection of fruit sweetness and crispness texture traits among fresh and dry jujubes. Our study not only illuminates the genetic basis of jujube evolution and domestication and provides a deep and rich genomic resource to facilitate both crop improvement and hypothesis‐driven basic research, but also identifies multiple agriculturally important genes for this unique perennial tree fruit species. [ABSTRACT FROM AUTHOR]

Objective: Lactulose is effective in the treatment and prevention of overt hepatic encephalopathy (OHE), but there are limited data on its use on microbiota in relations to minimal hepatic encephalopathy (MHE) recovery. The present study aimed to assess the efficacy of lactulose in recovery of MHE in aspects of cognitive function, quality of life, and impact on intestinal microbiota. Methods: This multicenter, open‐label randomized controlled trial was conducted in 11 teaching hospitals in China. Participants were randomly allocated on a 2:1 basis to receive lactulose (Gp‐L) or no therapy as control (Gp‐NL) for 60 days. The primary endpoint was the MHE reversal rate. Gut microbiota were compared between MHE patients and healthy volunteers, as well as lactulose‐responders and non‐responders. Results: A total of 98 cirrhotic patients were included in the study, with 31 patients in the Gp‐NL group and 67 patients in the Gp‐L group. At day 60, the MHE reversal rate in Gp‐L (64.18%) was significantly higher than that in Gp‐NL (22.58%) (P =.0002) with a relative risk of 0.46 (95% confidence interval 0.32‐0.67). Number needed to treat was 2.4. Further, there was significantly more improvement in physical functioning in Gp‐L (4.62 ± 6.16) than in Gp‐NL (1.50 ± 5.34) (P =.0212). Proteobacteria was significantly higher in MHE patients compared with healthy volunteers (12.27% vs 4.65%, P < .05). Significant differences were found between lactulose responders and non‐responders in Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. Conclusions: Treatment with lactulose significantly improves MHE recovery rate, and gut microbiota change in MHE patients can modulate the effectiveness of this therapy. Chinese Clinical Trial Register (ChiCTR) (ID: ChiCTR‐TRC‐12002342). [ABSTRACT FROM AUTHOR]

Background: The association between smoking and nasopharyngeal carcinoma (NPC) is still uncertain. The aim of this study was to validate smoking effect on NPC and explore if smoking can induce NPC by persistently reactivating EBV in long‐term based on a prospective cohort design. Methods: A NPC screening cohort with 10 181 eligible residents in Sihui city, southern China was conducted from 2008 to 2015. The smoking habit was investigated through the trained interviewers and EBV antibodies (VCA‐IgA, EBNA1‐IgA) as screening markers were tested periodically. New NPC cases were identified through local cancer registry. Cox's regression model was used to estimate the adjusted hazard ratios (aHRs) of smoking on NPC incidence. In the non‐NPC participants, the associations between smoking and EBV seropositivity in different periods were assessed by logistic regression and generalized estimating equations (GEE). Results: With a median of 7.54 years, 71 NPCs were diagnosed ≥1 year after recruitment. Compared with never smokers, the aHRs of developing NPC among ever smokers were 3.00 (95%CI: 1.46‐6.16). Stratified by sex, the HRs of ever smoking were 2.59 (95%CI: 1.07‐6.23) for male and 3.75 (95%CI: 1.25‐11.20) for female, respectively. Among the non‐NPC individuals, ever smoking was not only associated with EBV seropositivity at baseline, but also in the 3‐5 years of follow up, with adjusted odds ratios (aORs) of 1.68 (95%CI: 1.29‐2.18) for VCA‐IgA and 1.92 (95%CI: 1.42‐2.59) for EBNA1‐IgA. Among the smokers who were tested EBV antibodies at least twice, the similar results were obtained using GEE. Conclusion: Smoking could significantly increase the long‐term risk of NPC in southern China, partly by persistently reactivating EBV. [ABSTRACT FROM AUTHOR]

The article reports that alcoholic liver disease (ALD), induced by long-term heavy alcohol consumption, encompasses a progressive clinical-histological spectrum of liver injuries from simple fatty liver to alcoholic hepatitis, hepatic fibrosis and cirrhosis. It notes that hepatitis virus infection exerts a synergistic effect on alcohol-induced liver injury. It adds that ALD could both accelerate the development and progression of liver diseases.

The article reports that non-alcoholic fatty liver disease (NAFLD) is an acquired metabolic stress-induced liver disease associated closely with genetic susceptibility and insulin resistance. It notes that major risk factors for NAFLD include obesity-related high-calorie dietary rich in saturated fat and fructose, and sedentary lifestyles. It adds that increased waist circumference and IR have a strong correlation with NAFLD than increased subcutaneous fat deposit and high body mass index.

Abstract: Ecological stoichiometry connects different levels of biology, from the gene to the globe, by scaling up elemental ratios (e.g. carbon [C], nitrogen [N] and phosphorus [P]). Thus, ecological stoichiometry could be a powerful tool for revealing certain physiological processes of plants. However, C:N:P stoichiometry remains unclear at the community and ecosystem levels, despite it being potentially important for primary productivity. In this study, we measured the C, N and P contents of different plant organs, litter and soil in nine natural forest ecosystems (from cold‐temperate to tropical forests along a 3,700‐km transect in China) to explore C:N:P stoichiometry and the main influencing factors. C:N:P stoichiometry was evaluated for different components in the forest ecosystems (plant community, soil, litter and ecosystem) and, at the community level, for different organs (leaves, branches, trunks and roots) from 803 plant species. The ratios of C:P and N:P decreased with increasing latitude, with spatial patterns being primarily regulated by climate. Interestingly, the homeostasis of N, P and N:P was highest in leaves, followed by branches, roots and trunks, supporting the hypothesis that more active organs have a higher capacity to maintain relatively stable element content and ratios. At the community level, the leaf N:P ratio indicated increasing P limitation in forests of lower latitude (i.e. more southerly) in China's forests. Our findings demonstrate the spatial patterns of C:N:P stoichiometry and the strategies of element distribution among different organs in a plant community, providing important data on C:N:P to improve the parameterization of future ecological models. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Upland forests are traditionally thought to be net sinks for atmospheric methane ( CH4). In such forests, in situ CH4 fluxes on tree trunks have been neglected relative to soil and canopy fluxes., We measured in situ CH4 fluxes from the trunks of living trees and other surfaces, such as twigs and soils, using a static closed-chamber method, and estimated the CH4 budget in a temperate upland forest in Beijing., We found that the trunks of Populus davidiana emitted large quantities of CH4 during July 2014-July 2015, amounting to mean annual emissions of 85.3 and 103.1 μg m−2 h−1 on a trunk surface area basis on two replicate plots. The emission rates were similar in magnitude to those from tree trunks in wetland forests. The emitted CH4 was derived from the heartwood of trunks. On a plot or ecosystem scale, trunk CH4 emissions were equivalent to c. 30-90% of the amount of CH4 consumed by soils throughout the year, with an annual average of 63%., Our findings suggest that wet heartwoods, regardless of rot or not, occur widely in living trees on various habitats, where CH4 can be produced. [ABSTRACT FROM AUTHOR]

After converting cropland to forest, carbon is sequestered in the aggrading biomass of the new forests, but the question remains, to what extent will the former arable soil contribute as a sink for CO2? Quantifying changes in soil carbon is an important consideration in the large-scale conversion of cropland to forest. Extensive field studies were undertaken to identify a number of suitable sites for comparison of soil properties under pasture and forest. The present paper describes results from a study of the effects of first rotation larch on soil carbon in seven stands in an afforestation chronosequence compared with adjacent Korean pine, pasture, and cropland. An adjacent 250-year-old natural forest was included to give information on the possible long-term changes in soil carbon in northeast China in 2004. Soil carbon initially decreased during the first 12 yr before a gradual recovery and accumulation of soil carbon occurred. The initial (0–12 yr) decrease in soil carbon was an average 1.2% per year among case studies, whereas the increase in soil carbon (12–33 yr) was 1.90% per year. Together with the carbon sequestration of forest floors, this led to total soil carbon stores of approximately 101.83 Mg/hm2 over the 33-year chronosequence. Within the relatively short time span, carbon sequestration occurred mainly in tree biomass, whereas soil carbon stores were clearly higher in the 250-year-old plantation (184 Mg/hm2). The ongoing redistribution of mineral soil carbon in the young stands and the higher soil carbon contents in the 250-year-old afforested stand suggest that nutrient-rich afforestation soils may become greater sinks for carbon (C) in the long term. (Managing editor: Ya-Qin Han) [ABSTRACT FROM AUTHOR]