Interpretable machine learning models for predicting 90-day death in patients in the intensive care unit with epilepsy.

PURPOSE: This study aims to develop a machine learning-based model for predicting mortality risk in patients with epilepsy admitted to the intensive care unit (ICU), providing clinicians with an accurate prognostic tool to guide individualized treatment. METHODS: We collected clinical data from clinical databases (MIMIC IV and eICU-CRD) of epilepsy patients 24 h after ICU admission. The clinical characteristics of ICU patients with epilepsy were carefully feature selected and processed. MIMIC IV as the training set and eICU-CRD database as the test set. Six models were developed and validated, and the best LightGBM model was selected by performance comparison and analysed for interpretability. RESULTS: The final cohort comprised 429 patients for training and 1217 for testing. The training set exhibited a 90-day mortality rate of 9.32 %, and the test set had an in-hospital 90-day mortality rate of 4.10 %. Utilizing the LightGBM model, we achieved an AUC of 0.956 in the training set. External validation demonstrated promising results with accuracy of 0.898, precision of 0.975, AUC of 0.781, F1 score of 0.945, highlighting the model's potential for guiding clinical decision-making. Significant factors influencing model performance included the severity of illness, as measured by the OASIS score, and clinical parameters like heart rate and body temperature. CONCLUSION: This study introduces a machine learning-based approach to predict mortality risk in ICU epilepsy patients, offering a valuable tool for clinicians to identify high-risk individuals and devise personalized treatment strategies, thus improving patient prognosis and treatment outcomes.

Flying squirrels use a mortise-tenon structure to fix nuts on understory twigs.

Squirrels of temperate zones commonly store nuts or seeds under leaf litter, in hollow logs, or even in holes in the ground; however, in the humid rainforests of Jianfengling in Hainan, South China, we show that some flying squirrels cache elliptical or oblate nuts by hanging them securely in vegetation. These small flying squirrels were identified as Hylopetes phayrei electilis (G. M. Allen, 1925) and Hylopetes alboniger (Hodgson, 1870), in video clips captured of their behavior around focal nuts. Squirrels chewed grooves encircling ellipsoid nuts or distributed on the bottoms of oblate nuts, and then used these grooves to fix nuts tightly between small twigs 0.1-0.6 cm in diameter that were connected at angles of 25-40°. The grooves carved on the nuts (concave structure) connected with Y-shaped twigs (convex structure) and thus firmly affixed the nuts to the plant in a way similar to a mortise-tenon joint used in architecture and carpentry. Cache sites were on small plants located 10-25 m away from the closest potentially nut-producing tree, a behavior that likely reduces the discovery and consumption of the nuts by other animals. The adaptive squirrel behavior that shapes and fits nuts between twigs seems to be directed at providing more secure storage that increases food supply during dry periods in a humid tropical rainforest. In addition to providing such benefits for the squirrels, we suggest that this behavior also impacts the distribution of tree species in the forest.

The rainy forests of South China are home to Cyclobalanopsis trees whose smooth, elliptical nuts are favoured by many animal species. While doing fieldwork in the Jianfengling nature reserve in the southern province of Hainan, China, researchers came across an unusual sight: many of these nuts had been wedged into the Y-shaped forks between diverging twigs. A closer inspection revealed that a carefully crafted groove on the surface of the nuts helped them to stay wedged and secured between the branches. Which creature was responsible for such a feat? To investigate, Xu et al. set up motion-triggered, infra-red cameras near some of the hoarding sites. They discovered that the culprits were Hylopetes phayrei electilis and Hylopetes alboniger, two small species of flying squirrel that tend to store Cyclobalanopsis nuts to prepare for the dry, cool season. The footage showed that the squirrels first chewed the nuts before inserting them tightly between the branches. In fact, this process appeared to require much care ­ and, potentially, cognitive involvement ­ with the squirrels testing and adjusting their grooves many times until a perfect fit was achieved. Caching sites were usually found 10 to 25 meters away from the nearest Cyclobalanopsis tree, which probably helps to protect the hoards from other animals on the hunt for nuts. Squirrels from temperate regions typically prepare for winter by hiding food in the ground, between logs or inside hollow trees; in humid, tropical forests, however, such caching sites may promote mould, decomposition or germination. In these conditions, securely hanging nuts between branches may prove to be a more suitable strategy. By choosing caching sites that are away from the mother tree, squirrels may also inadvertently help Cyclobalanopsis to expand their range, with forgotten nuts becoming dislodged and sprouting in new locations across the reserve. Overall, these findings shed new light on animal adaptation and cognition, as well as on the forces that help to shape forest ecology.

Long-term phosphorus addition alleviates CO2 and N2O emissions via altering soil microbial functions in secondary rather primary tropical forests.

Tropical forests, where the soils are nitrogen (N) rich but phosphorus (P) poor, have a disproportionate influence on global carbon (C) and N cycling. While N deposition substantially alters soil C and N retention in tropical forests, whether P input can alleviate these N-induced effects by regulating soil microbial functions remains unclear. We investigated soil microbial taxonomy and functional traits in response to 10-year independent and interactive effects of N and P additions in a primary and a secondary tropical forest in Hainan Island. In the primary forest, N addition boosted oligotrophic bacteria and phosphatase and enriched genes responsible for C-, P-mineralization, nitrification and denitrification, suggesting aggravated P limitation while N excess. This might stimulate P excavation via organic matter mineralization, and enhance N losses, thereby increasing soil CO2 and N2O emissions by 86% and 110%, respectively. Phosphorus and NP additions elevated C-mining enzymes activity mainly due to intensified C limitation, causing 82% increase in CO2 emission. In secondary forest, P and NP additions reduced phosphatase activity, enriched fungal copiotrophs and increased microbial biomass, suggesting removal of nutrient deficiencies and stimulation of fungal growth. Meanwhile, soil CO2 emission decreased by 25% and N2O emission declined by 52-82% due to alleviated P acquisition from organic matter decomposition and increased microbial C and N immobilization. Overall, N addition accelerates most microbial processes for C and N release in tropical forests. Long-term P addition increases C and N retention via reducing soil CO2 and N2O emissions in the secondary but not primary forest because of strong C limitation to microbial N immobilization. Further, the seasonal and annual variations in CO2 and N2O emissions should be considered in future studies to test the generalization of these findings and predict and model dynamics in greenhouse gas emissions and C and N cycling.

Development and validation of a nomogram for predicting atrial fibrillation in patients with acute heart failure admitted to the ICU: a retrospective cohort study.

INTRODUCTION: Acute heart failure is a serious condition. Atrial fibrillation is the most frequent arrhythmia in patients with acute heart failure. The occurrence of atrial fibrillation in heart failure patients worsens their prognosis and leads to a substantial increase in treatment costs. There is no tool that can effectively predict the onset of atrial fibrillation in patients with acute heart failure in the ICU currently. MATERIALS AND METHODS: We retrospectively analyzed the MIMIC-IV database of patients admitted to the intensive care unit (ICU) for acute heart failure and who were initially sinus rhythm. Data on demographics, comorbidities, laboratory findings, vital signs, and treatment were extracted. The cohort was divided into a training set and a validation set. Variables selected by LASSO regression and multivariate logistic regression in the training set were used to develop a model for predicting the occurrence of atrial fibrillation in acute heart failure in the ICU. A nomogram was drawn and an online calculator was developed. The discrimination and calibration of the model was evaluated. The performance of the model was tested using the validation set. RESULTS: This study included 2342 patients with acute heart failure, 646 of whom developed atrial fibrillation during their ICU stay. Using LASSO and multiple logistic regression, we selected six significant variables: age, prothrombin time, heart rate, use of vasoactive drugs within 24 h, Sequential Organ Failure Assessment (SOFA) score, and Acute Physiology Score (APS) III. The C-index of the model was 0.700 (95% CI 0.672-0.727) and 0.682 (95% CI 0.639-0.725) in the training and validation sets, respectively. The calibration curves also performed well in both sets. CONCLUSION: We developed a simple and effective model for predicting atrial fibrillation in patients with acute heart failure in the ICU.

Three-dimensional printed lithium iron phosphate coated with magnesium oxide cathode with improved areal capacity and ultralong cycling stability for high performance lithium-ion batteries.

Three-dimensional (3D) printing of Li-ion batteries with unconventional 3D electrodes has attracted considerable attention in recent years. However, fabricating 3D electrodes with high specific capacity, high areal capacity, ultralong cycling stability, and improved rate performance remains a challenge to date. Novel 3D grid-patterned LiFePO4@MgO composite electrodes with thicknesses of 143, 306, and 473 µm were fabricated via 3D printing. The electrochemical performance of half cells was evaluated. The 3D-printed LiFePO4@MgO (143 µm) electrodes exhibit stable specific capacities of 142.8 mAh g-1 @ 1.0 C and 90.3 mAh g-1 @ 10.0 C after 800 and 1700 cycles, respectively. In addition, the 473 µm-thick 3D grid-patterned LiFePO4@MgO achieves an areal capacity of 3.01 mAh cm-2 @ 0.1 C after 20 cycles. The full cells comprised 143 µm-thick 3D-printed LiFePO4@MgO, and 217 µm Li4Ti5O12 electrodes show a capacity of 139.0 mAh g-1 @ 1.0 C after 400 cycles. These results indicate that, this type of thick 3D-printed LiFePO4@MgO electrode achieves high capacity, high-rate capability, and ultralong cycle stability. The outstanding performance ascribes the fast electrolyte infusion of 3D-printed electrodes and the enhanced electronic/ionic transport.

Red blood cell distribution width predicts in-hospital mortality in patients with a primary diagnosis of seizures in the ICU: a retrospective database study.

PURPOSE: The aim of this study was to determine the predictive value of red blood cell distribution width (RDW) in patients with a primary diagnosis of seizures admitted to the intensive care unit (ICU) in terms of in-hospital mortality. METHODS: This was a retrospective study of the eICU Collaborative Research Database of adult patients (aged 18-88 years) with a primary diagnosis of seizures in 2014 and 2015. The prognostic value of RDW was investigated using a receiver operating characteristic (ROC) curve, multiple logistic regression model, and net reclassification index (NRI). RESULTS: We identified 1568 patients who met the inclusion criteria. High RDW was significantly correlated with in-hospital mortality after adjusting for potential confounders with an odds ratio (OR) of 3.513 (95% confidence interval [CI]:1.699-7.266). The area under the ROC curve of RDW for in-hospital mortality was 0.7225. Compared with the prediction of in-hospital mortality using APACHE IV score alone, the continuous NRI with the RDW variable was 0.3507 (95%CI: 0.0584-0.6431, p < 0.05). The length of stay in the ICU of patients with an RDW >14.65% was significantly increased compared to those with normal RDW (log-rank test, p < 0.0001). CONCLUSION: RDW width can be useful for prediction of in-hospital mortality in patients with seizures admitted to the ICU, and it provides additional prognostic value beyond the APACHE IV score alone.

Loss of soil microbial residue carbon by converting a tropical forest to tea plantation.

Land-use change can lead to profound changes in the storage of soil organic carbon (SOC) in the tropics. Soil microbial residues make up the majority of persistent SOC pools, yet the impact of land-use change on microbial residue C accumulation in the tropics is not well understood. Here, we investigated how the conversion of tropical primary montane rainforest to secondary forest and the conversions of secondary forest to Prunus salicina plantation and tea plantation, influence the accumulation of soil microbial residue C (indicated by amino sugars). Our results showed that the secondary forest had a higher SOC than that of the primary forest (+63%), while they had no difference in microbial residue C concentration, indicating a relatively slow microbial-derived C accrual during secondary succession. Moreover, the P. salicina plantation and tea plantation had lower SOC than the secondary forest (-53% and -57%, respectively). A decrease in fungal biomass (-51%) resulted in less fungal and total residue C concentrations in the tea plantation than in the secondary forest (-38% and -35%, respectively), indicating microbial-derived C loss following the forest conversion. The change in microbial residue C depended on litter standing crop rather than soil nutrient and root biomass. Litter standing crop affected microbial residue C concentration by regulating fungal biomass and hydrolytic enzyme activities. Taken together, our results highlight that litter-microbe interactions drive microbial residue C accumulation following forest conversions in the tropics.

Gross ecosystem product accounting of national park: Taking Hainan Tropical Rainforest National Park as an example.

Hainan Tropical Rainforest National Park has the most representative and largest contiguous tropical rainforest in China, which has advantages in exploring the realization mechanism of ecological product value in national parks. Based on the basic framework of "The Technical Guideline on Gross Ecosystem Product (GEP)", we constructed a GEP accounting system in line with the characteristics of tropical rain forest national park, and calculated the GEP of Hainan Tropical Rainforest National Park in 2019. The results showed that the GEP of Hainan Tropical Rainforest National Park in 2019 was 204.513 billion yuan, and the GEP per unit area was 0.046 billion yuan·km-2. Among all the service types, the value of material services was 4.850 billion yuan, accounting for 2.4% of the total GEP in the national park. The ecosystem regulation service value was 168.891 billion yuan, accounting for 82.6%. The value of cultural services was 30.772 billion yuan, accounting for 15.0%. Among different ecosystem types, the unit area value of the tropical rain forest ecosystem represented by mountain rain forest, lowland rain forest, deciduous monsoon forest, and tropical cloud forest was much higher than that of plantation or other ecosystems, indicating the dominant role of tropical rain forest ecosystem in providing ecosystem services. In addition, based on the GEP accounting results of the national park, we put forward relevant suggestions for further exploring the realization path and realization mechanism of ecological product value.

Arbuscular mycorrhizal trees influence the latitudinal beta-diversity gradient of tree communities in forests worldwide.

Arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) associations are critical for host-tree performance. However, how mycorrhizal associations correlate with the latitudinal tree beta-diversity remains untested. Using a global dataset of 45 forest plots representing 2,804,270 trees across 3840 species, we test how AM and EcM trees contribute to total beta-diversity and its components (turnover and nestedness) of all trees. We find AM rather than EcM trees predominantly contribute to decreasing total beta-diversity and turnover and increasing nestedness with increasing latitude, probably because wide distributions of EcM trees do not generate strong compositional differences among localities. Environmental variables, especially temperature and precipitation, are strongly correlated with beta-diversity patterns for both AM trees and all trees rather than EcM trees. Results support our hypotheses that latitudinal beta-diversity patterns and environmental effects on these patterns are highly dependent on mycorrhizal types. Our findings highlight the importance of AM-dominated forests for conserving global forest biodiversity.

Albumin Level at Admission to the Intensive Care Unit Is Associated With Prognosis in Cardiac Arrest Patients.

Aim Cardiac arrest is a global health concern with consistently high mortality. It is also a common condition seen in the intensive care unit (ICU). We aimed to investigate the importance of albumin level on admission, which is a widely available and simple test, to predict in-hospital mortality in cardiac arrest patients. Methods The retrospective study collected data from the eICU Collaborative Research Database. It contains data from 171 hospitals, 276 ICU wards, and 4,529 patients who were treated for cardiac arrest from 2014 to 2015. We analyzed the patients' laboratory results and vital signs during the first 24 hours after admission to the ICU. The primary outcome was in-hospital mortality, and the secondary outcome was the length of ICU stay among survivors. Results In total, 2,414 patients were eligible. After adjusting for severity scores, including the Acute Physiology and Chronic Health Evaluation (APACHE) IV and Sequential Organ Failure Assessment (SOFA) scores, serum albumin was found to be a protective factor for survival (odds ratio of mortality: 0635, 95% confidence interval: 0.458-0.734, P<0.001). Among patients who survived until discharge, those with hypoalbuminemia had a long duration of stay in the ICU (P=0.005). Conclusion The higher albumin level at admission to the ICU was associated with lower mortality in patients with cardiac arrest.

Species packing and the latitudinal gradient in beta-diversity.

The decline in species richness at higher latitudes is among the most fundamental patterns in ecology. Whether changes in species composition across space (beta-diversity) contribute to this gradient of overall species richness (gamma-diversity) remains hotly debated. Previous studies that failed to resolve the issue suffered from a well-known tendency for small samples in areas with high gamma-diversity to have inflated measures of beta-diversity. Here, we provide a novel analytical test, using beta-diversity metrics that correct the gamma-diversity and sampling biases, to compare beta-diversity and species packing across a latitudinal gradient in tree species richness of 21 large forest plots along a large environmental gradient in East Asia. We demonstrate that after accounting for topography and correcting the gamma-diversity bias, tropical forests still have higher beta-diversity than temperate analogues. This suggests that beta-diversity contributes to the latitudinal species richness gradient as a component of gamma-diversity. Moreover, both niche specialization and niche marginality (a measure of niche spacing along an environmental gradient) also increase towards the equator, after controlling for the effect of topographical heterogeneity. This supports the joint importance of tighter species packing and larger niche space in tropical forests while also demonstrating the importance of local processes in controlling beta-diversity.

Association Between Red Cell Distribution Width and Hospital Mortality in Patients with Sepsis.

OBJECTIVE: Sepsis is the leading cause of death in patients admitted to adult intensive care units (ICUs). We aimed to determine the predictive value of red blood cell distribution width (RDW) in patients with sepsis in a large cohort. METHODS: This retrospective observational study used data from the eICU Collaborative Research Database. The prognostic value of RDW was investigated using the receiver operating characteristic (ROC) curve, multiple logistic regression model, integrated discriminatory index (IDI), and net reclassification index (NRI). RESULTS: In total, 9743 patients were included. The area under the ROC curve of the RDW for predicting hospital mortality was 0.631 (95% confidence interval [CI]: 0.616-0.645). Based on the multiple logistic regression model, an RDW of ≥14.5% was correlated with hospital mortality, regardless of Sequential Organ Failure Assessment (SOFA) and Acute Physiology and Chronic Health Evaluation IV (APACHE IV) scores (odds ratio [OR]: 1.838, 95% CI: 1.598-2.119). Using SOFA and APACHE IV scores as reference, the IDI and continuous NRI of RDW for hospital mortality was about 0.3 and 0.014, respectively. CONCLUSIONS: The RDW may be useful in predicting hospital mortality in patients with sepsis, offering extra prognostic value beyond SOFA and APACHE IV scores.

Soil nitrogen concentration mediates the relationship between leguminous trees and neighbor diversity in tropical forests.

Legumes provide an essential service to ecosystems by capturing nitrogen from the atmosphere and delivering it to the soil, where it may then be available to other plants. However, this facilitation by legumes has not been widely studied in global tropical forests. Demographic data from 11 large forest plots (16-60 ha) ranging from 5.25° S to 29.25° N latitude show that within forests, leguminous trees have a larger effect on neighbor diversity than non-legumes. Where soil nitrogen is high, most legume species have higher neighbor diversity than non-legumes. Where soil nitrogen is low, most legumes have lower neighbor diversity than non-legumes. No facilitation effect on neighbor basal area was observed in either high or low soil N conditions. The legume-soil nitrogen positive feedback that promotes tree diversity has both theoretical implications for understanding species coexistence in diverse forests, and practical implications for the utilization of legumes in forest restoration.

The Structure and Species Co-Occurrence Networks of Soil Denitrifying Bacterial Communities Differ Between A Coniferous and A Broadleaved Forests.

Acacia mangium (AM) and Pinus massoniana (PM) are widely planted in tropical regions, whereas their effects on soil microbial communities remain unclear. We did a comprehensive investigation of soil denitrifying bacterial communities in AM and PM monoculture plantations in Southern China based on the high throughput sequencing data of their functional genes: nirK, nirS, and nosZ. The average abundance of nosZ (1.3 × 107) was significantly higher than nirS (5.6 × 106) and nirK (4.9 × 105). Shannon estimator revealed a markedly higher α-diversity of nirS and nosZ communities in PM than in AM plantations. The AM and PM plantations were dominated by different nirS and nosZ taxa belonging to proteobacteria, actinobacteria, thermoleophilia, chloroflexia, and acidobacteria, while the dominant nirK taxa were mainly categorized into proteobacteria in both types of plantations. The structure of nirS and nosZ communities shifted substantially from AM to PM plantations with changes in soil moisture, NH4+, and microbial biomass nitrogen content. The species co-occurrence network of nirK community was better organized in a more modular manner compared to nirS and nosZ communities, and the network keystone species mostly occurred in PM plantations. These results indicated a highly species corporation of nirK community in response to environmental changes, especially in PM plantations. AM and PM plantations can form different soil denitrifying microbial communities via altering soil physicochemical properties, which may further affect soil N transformations.

[Influence of LBP alone or Combined with TRAIL on Apoptosis of MLL Rearranged Leukemic Cells].

OBJECTIVE: To investigate the effect of lycium barbarum polysaccharide (LBP) alone or combined with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) on the apoptosis of leukemia cell lines with MLL gene-rearrangement, and to explore the cell apoptotic pathway after the combined action. METHODS: MLL-ALL cell line KOCL44 and KOCL45 were selected as the research object, then the control and experimental groups were set up. The cell survival rate was measured by the trypan blue dye exclusion method, the cell early apoptosis and expression of death receptors on the cell surface were detected by flow cytometry with Annexin-V/PI double staining. The protein level of caspase-8, BID, caspase-3, caspase-9, BAD, BCL-2, as well as mitochondrial and cytosol Cyto-C were detected by Western blot. RESULTS: LBF combined with TRAIL inhibited the growth of KOCL44 and KOCL-45 cells and showed the synergistic effect, the results of flow cytometry with Amnexiu V/PI double staining were consistent with above-mentioned results. After treatment of KOCL44 and KOCL45 cells with LBF plus TRAIL, the significant expression of DR4 on cell surface was not found, while the expression of DR4 receptor was enhanced significantly, the pro-apoptotic proteins including caspase-8, BID, caspase-3, caspase-9 and BAD were activated significantly and BCL-2 was suppressed significantly with time-dependent manner. The expression of mitochondria cyto-C in KOCL44 and KOCL45 decreased along with prolonging of treatment time (r=-0.95, r=-0.866), while the expression of cytosol cyto-C in KOCL44 and KOCL45 increased along with prolonging of treatment time (r=0.883, r=0.903). CONCLUSION: The combination of LBP and TRAIL significantly increases the apoptosis of KOCL44 and KOCL45, and the LBP and TRAIL can up-regulate the expression of TRAIL death receptor-DR5 on the cell surface, activate the pathway of caspase and mito-chrondia mitachondria, thus enhance the sensitivity of KOCL44 and KOCL45 to TRAIL induced apoptosis through both mitochondrial and apoptotic pathway.

The Composition of Nitrogen-Fixing Microorganisms Correlates With Soil Nitrogen Content During Reforestation: A Comparison Between Legume and Non-legume Plantations.

Numerous reforestation projects have been conducted to improve soil fertility in degraded forests, often causing alterations to the soil microbial communities. However, it remains unclear whether microbial functional groups are affected and how these groups correlate with an increase in the nutrient contents during reforestation. We investigated the abundance and composition of free-living nitrogen-fixing microorganisms (diazotrophs) by quantifying and sequencing the marker gene nifH in bulk soils from five reforestation approaches, including legumes and non-legumes, in subtropical China. The relationships between diazotrophic community attributes and soil nitrogen (N) content [NO3 -, NH4 +, and microbial biomass N (MBN)] were examined under various approaches. Abundance of diazotrophs was highest in the native tree plantation (Schima spp. and Michelia macclurei) and Acacia mangium monoculture (AM), and lowest in the Pinus massoniana monoculture. The diazotrophic abundance correlated positively with soil organic matter and water content while there was a negative correlation to pH. The composition of diazotrophic community differed significantly among the five reforestation approaches examined and was closely correlated with variations in soil pH, NH4 + and water content. Diazotrophic community composition was closely related to soil NH4 + content, whereas abundance was not. The AM contained higher NH4 +, NO3 - and MBN contents than the other reforestation approaches, which may be associated with the indicator species of diazotrophs (Actinobacteria, Proteobacteria, and Firmicutes). However, there were more indicator species of Proteobacteria in the mixed Acacia plantation (Acacia mangium and Acacia crassicarpa) than in AM, which might have contributed to the remarkedly lower N content compared to AM. Overall, the soil N content under reforestation appeared to be more related to the composition of diazotroph community than to the abundance of diazotrophs.

An efficient and cost-effective method for primer-induced nucleotide labeling for massive sequencing on next-generation sequencing platforms.

Next generation sequencing (NGS) technologies play a powerful role in the preparation of large DNA databases such as DNA barcoding since it can produce a large number of sequence reads. Here we demonstrate a primer-induced sample labeling method aiming at sequencing a large number of samples simultaneously on NGS platforms. The strategy is to label samples with a unique oligo attached to the 5'-ends of primers. As a case study, 894 unique pentanucleotide oligoes were attached to the 5'-ends of three pairs of primers (for amplifying ITS, matK and rbcL) to label 894 samples. All PCR products of three barcodes of 894 samples were mixed together and sequenced on a high throughput sequencing platform. The results showed that 87.02%, 89.15% and 95.53% of the samples were successfully sequenced for rbcL, matK and ITS, respectively. The mean ratio of label mismatches for the three barcodes was 5.68%, and a sequencing depth of 30 ×to 40× was enough to obtain reliable sequences. It is flexible to label any number of samples simply by adjusting the length of oligoes. This easy, reliable and cost efficient method is useful in sequencing a large number of samples for construction of reference libraries for DNA barcoding, population biology and community phylogenetics.

Direct and indirect effects of climate on richness drive the latitudinal diversity gradient in forest trees.

Climate is widely recognised as an important determinant of the latitudinal diversity gradient. However, most existing studies make no distinction between direct and indirect effects of climate, which substantially hinders our understanding of how climate constrains biodiversity globally. Using data from 35 large forest plots, we test hypothesised relationships amongst climate, topography, forest structural attributes (stem abundance, tree size variation and stand basal area) and tree species richness to better understand drivers of latitudinal tree diversity patterns. Climate influences tree richness both directly, with more species in warm, moist, aseasonal climates and indirectly, with more species at higher stem abundance. These results imply direct limitation of species diversity by climatic stress and more rapid (co-)evolution and narrower niche partitioning in warm climates. They also support the idea that increased numbers of individuals associated with high primary productivity are partitioned to support a greater number of species.

Contrasting Soil Bacterial Community, Diversity, and Function in Two Forests in China.

Bacteria are the highest abundant microorganisms in the soil. To investigate bacteria community structures, diversity, and functions, contrasting them in four different seasons all the year round with/within two different forest type soils of China. We analyzed soil bacterial community based on 16S rRNA gene sequencing via Illumina HiSeq platform at a temperate deciduous broad-leaved forest (Baotianman, BTM) and a tropical rainforest (Jianfengling, JFL). We obtained 51,137 operational taxonomic units (OTUs) and classified them into 44 phyla and 556 known genera, 18.2% of which had a relative abundance >1%. The composition in each phylum was similar between the two forest sites. Proteobacteria and Acidobacteria were the most abundant phyla in the soil samples between the two forest sites. The Shannon index did not significantly differ among the four seasons at BTM or JFL and was higher at BTM than JFL in each season. The bacteria community at both BTM and JFL showed two significant (P < 0.05) predicted functions related to carbon cycle (anoxygenic photoautotrophy sulfur oxidizing and anoxygenic photoautotrophy) and three significant (P < 0.05) predicted functions related to nitrogen cycle (nitrous denitrificaton, nitrite denitrification, and nitrous oxide denitrification). We provide the basis on how changes in bacterial community composition and diversity leading to differences in carbon and nitrogen cycles at the two forests.

Plant Functional Traits Are the Mediators in Regulating Effects of Abiotic Site Conditions on Aboveground Carbon Stock-Evidence From a 30 ha Tropical Forest Plot.

Understanding the relative contribution of abiotic and biotic factors to the formation of ecosystem functioning across scales is vital to evaluate ecosystem services. Here, we elucidate the effects of abiotic site conditions (i.e., soil and topographic properties) and plant functional traits on variations of stand aboveground carbon (AGC) stock in an old-growth tropical montane rain forest. The response-effect framework in functional ecology is adopted in examining how plant functional traits respond to environmental changes and affect ecosystem functioning. We measured specific leaf area and wood density of 270 woody plant species and estimated stand AGC stocks in a 30-ha forest plot. The relationships among environmental factors (ENVIRONMENT), community-weighted means of functional traits (TRAITS) and stand AGC stocks across nested spatial scales were disentangled by structural equation modeling. The results showed that the stands composed of 'acquisitive' species (high specific leaf area and low wood density) had low AGC, whereas stands composed of 'conservative' species (low specific leaf area and high wood density) had high AGC. TRAITS responded to ENVIRONMENT and affected AGC directly. ENVIRONMENT had an indirect effect on AGC through its direct effect on TRAITS. TRAITS were more important than ENVIRONMENT in driving variations of AGC. The effects of TRAITS on AGC increased, while the effects of ENVIRONMENT on AGC decreased with the increase of spatial scales in the tropical montane rain forest. Our study suggests that plant functional traits are the mediators in regulating effects of abiotic site conditions on ecosystem functions.