Spatial and temporal analysis of beta diversity in the Barro Colorado Island forest dynamics plot, Panama

Background: Ecologists are interested in assessing the spatial and temporal variation in ecological surveys repeated over time. This paper compares the 1985 and 2015 surveys of the Barro Colorado Forest Dynamics plot(BCI), Panama,divided into 1250(20 m × 20 m) quadrats.Methods, spatial analysis: Total beta diversity was measured as the total variance of the Hellinger-transformed community data throughout the BCI plot. Total beta was partitioned into contributions of individual sites(LCBD indices), which were tested for significance and mapped.Results, spatial analysis: LCBD indices indicated the sites with exceptional community composition. In 1985,they were mostly found in the swamp habitat. In the 2015 survey, none of the swamp quadrats had significant LCBDs.What happened to the tree community in the interval?Methods, temporal analysis: The dissimilarity in community composition in each quadrat was measured between time 1(1985) and time 2(2015). Temporal Beta Indices(TBI) were computed from abundance and presence-absence data and tested for significance. TBI indices can be decomposed into B = species(or abundances-per-species) losses and C = species(or abundances-per-species) gains. B-C plots were produced; they display visually the relative importance of the loss and gain components, through time, across the sites.Results, temporal analysis: In BCI, quadrats with significant TBI indices were found in the swamp area, which is shrinking in importance due to changes to the local climate. A published habitat classification divided the BCI forest plot into six habitat zones. Graphs of the B and C components were produced for each habitat group. Group 4(the swamp) was dominated by species(and abundances-per-species) gains whereas the five other habitat groups were dominated by losses, some groups more than others.Conclusions: We identified the species that had changed the most in abundances in the swamp between T1 and T2.This analysis supported the hypothesis that the swamp is drying out and is invaded by species from the surrounding area. Analysis of the B and C components of temporal beta diversity bring us to the heart of the mechanisms of community change through time: losses(B) and gains(C) of species, losses and gains of individuals of various species. TBI analysis is especially interesting in species-rich communities where we cannot examine the changes in every species individually.

Optimal plot design in a multipurpose forest inventory

Background： We explore the factors affecting the optimal plot design （size and type as well as the subsample tree selection strategies within a plot） and their relative importance in defining the optimal plot design in amultipurpose forest inventory. The factors include time used to lay out the plot and to make the tree measurements within the plot, the between-plot variation of each of the variables of interest in the area, and the measurement and model errors for the different variables. Methods： We simulate different plot types and sizes and subsample tree selection strategies on measuredtest areas from North Lapland. The plot types used are fixed-radius, concentric and relascope plots. Weselect the optimal type and size first at plot level using a cost-plus-loss approach and then at cluster level byminimizing the weighted standard error with fixed budget. Results： As relascope plots are ve~/efficient at the plot level for volume and basal area, and fixed-radius plots for stems per ha, the optimal plot type strongly depends on the relative importance of these variables. The concentric plot seems to be a good compromise between these two in many cases. The subsample tree selection strategy was more important in selecting optimal plot than many other factors. In cluster level, the most important factor is the transfer time between plots. Conclusions： While the optimal radius of plots and other parameters were sensitive to the measurement times and other cost factors, the concentric plot type was optimal in almost all studied cases. Subsample tree measurement strategies need further studies, as they were an important cost factor. However, their importance to the precision was not as clear.

A Survey of Mycorrhizal Colonization in the 50-ha Korup Forest Dynamic Plot in Cameroon

A study was carried out in the 50-ha Korup Forest Dynamic Plot in South West Cameroon, to evaluate the diversity of mycorrhizal associations as well as to determine the effect of habitat types on the type of mycorrhizal association. A total of 781 individual trees belonging to 51 families, 165 genera and 252 tree species, were sampled from the four habitat types found in the plot: low drier, hill slope, ridge top and wetland complexes. In each habitat type, all stems ≤ 1 cm depth at breast height had already been tagged, measured, mapped and identified to the species level. Root samples were collected, cleared, stained and examined microscopically for mycorrhizal type. Of the total number of species sampled, 248 (98.41%) formed mycorrhizal associations with only 4 (1.59%) being non mycorrhizal. For mycorrhizal trees, 232 (93.55%) formed exclusively arbuscular mycorrhiza, 10 (4.03%) formed ectomycorrhiza, while 6 (2.42%) formed both ecto- and arbuscular mycorrhiza. The ridge top harbored the least number (152) of mycorrhizal trees while the low drier area harbored the most number (266) of mycorrhizal trees. Although habitat effect was not significant in influencing mycorrhizal colonization of tree species, some tree species did show aggregated patterns in particular habitats.

Assessment of the State of Forests Based on Joint Statistical Processing of Sentinel-2B Remote Sensing Data and the Data from Network of Ground-Based ICP-Forests Sample Plots

The research was carried out on the territory of the Karelian Isthmus of the Leningrad Region using Sentinel-2B images and data from a network of ground sample plots. The ground sample plots are located in the studied territory mainly in a regular manner, laid and surveyed according to the ICP-Forests methodology with some additions. The total area of the sample plots is a small part of the entire study area. One of the objectives of the study was to determine the possibility of using the k-NN (nearest neighbor method) to assess the state of forests throughout the whole studied territory by joint statistical processing of data from ground sample plots and Sentinel-2B imagery. The data of the ground-based sample plots were divided into 2 equal parts, one for the application of the k-NN method, the second for checking the results of the method application. The systematic error in determining the mean damage class of the tree stands on sample plots by the k-NN method turned out to be zero, the random error is equal to one point. These results offer a possibility to determine the state of the forest in the entire study area. The second objective of the study was to examine the possibility of using the short-wave vegetation index (SWVI) to assess the state of forests. As a result, a close statistically reliable dependence of the average score of the state of plantations and the value of the SWVI index was established, which makes it possible to use the established relationship to determine the state of forests throughout the studied territory. The joint use and statistical processing of remotely sensed data and ground-based test areas by the two studied methods make it possible to assess the state of forests throughout the large studied area within the image. The results obtained can be used to monitor the state of forests in large areas and design appropriate forestry protective measures.

Sample Plot Change in the Seventh Review of Continuous National Forest Inventory in Zigui County

The following qualitative conclusions of forest resources in Zigui can be drawn by the research on 73 plots and 5 vegetation plots:forest area is increasing; forest growing stock is increasing; the adjustment of forest category structure is constantly improved; forest quality has been improving; stand structure is optimized continuously; biodiversity has initially appeared.

Coarse woody debris features of a warm temperate deciduous broad-leaved forest,northern China

Stocking and structural composition of a deciduous broad-leaved forest were determined to predict coarse woody debris quantity by quantifying the empirical relationships between these two attributes.The most ecologically significant families by stem density were Salicaceae,Betulaceae,Fagaceae,and Aceraceae.P opulus davidiana was the most dominant species followed by B etula dahurica,Quercus mongolica,and Acer mono.The four species accounted for 69.5%of total stems.Numerous small-diameter species characterized the coarse woody debris showing a reversed J-shaped distribution.The coarse debris of P.davidiana,B.dahurica,and Q.mongolica mainly comprised the 10–20 cm size class,whereas A.mono debris was mainly in the 5–10 cm size class.The spatial patterns of different size classes of coarse woody debris were analyzed using the g-function to determine the size of the tree at its death.The results indicate that the spatial patterns at the 0–50 m scale shifted gradually from an aggregated to a random pattern.For some species,the larger coarse debris might change from an aggregated to a random distribution more easily.Given the importance of coarse woody debris in forest ecosystems,its composition and patterns can improve understanding of community structure and dynamics.The aggregation pattern might be due to density dependence and self-thinning effects,as well as by succession and mortality.The four dominant species across the different size classes showed distinct aggregated distribution features at different spatial scales.This suggests a correlation between the dominant species population,size class,and aggregated distribution of coarse woody debris.

Fine-scale activity patterns of large-and medium-sized mammals in a deciduous broadleaf forest in the Qinling Mountains,China

The composition of animal species and interactions among them are widely known to shape ecological communities and fine-scale(e.g.,<1 km)monitoring of animal communities is essential for understanding the relationships among animals and plants.Although the co-existence of large-and medium-sized species has been studied across different scales,research on fine-scale interactions of herbivores in deciduous broadleaf forests is limited.Camera trapping of large-and medium-sized mammals was carried out over a 1 year period within a 25 ha deciduous broadleaf forest dynamics plot in the Qinling Mountains,China.Fourteen species of large-and medium-sized mammals,including six carnivores,six ungulates,one primate and one rodent species were found.Kernel density estimations were used to analyse the diel or 24 h activity patterns of all species with more than 40 independent detections and general linear models were developed to explore the spatial relationships among the species.The combination of overlapping diel activity patterns and spatial associations showed obvious niche separation among six species:giant panda(Ailuropoda melanoleuca David),takin(Budorcas taxicolor Hodgson),Reeves’s muntjac(Muntiacus reevesi Ogilby),tufted deer(Elaphodus cephalophus Milne-Edwards),Chinese serow(Capricornis milneedwardsii David)and wild boar(Sus scrofa Linnaeus).Long-term fine-scale monitoring is useful for providing information about the co-existence of species and their interactions.The results demonstrate the importance for fine-scale monitoring of animals and plants for improving understanding of species interactions and community dynamics.

Drivers of the differentiation between broad-leaved trees and shrubs in the shift from evergreen to deciduous leaf habit in forests of eastern Asian subtropics

In eastern Asian subtropical forests,leaf habit shifts from evergreen to deciduous broad-leaved woody plants toward higher latitudes.This shift has been largely explained by the greater capacity of deciduous broad-leaved plants to respond to harsh climatic conditions(e.g.,greater seasonality).The advantages of deciduous leaf habit over evergreen leaf habit in more seasonal climates have led us to hypothesize that leaf habits would shift in response to climate changes more conspicuously in forest canopy trees than in forest understory shrubs.Furthermore,we hypothesize that in the forests of the subtropics,plants at higher latitudes,regardless of growth form,would better tolerate seasonal harsh climates,and hence show less differentiation in leaf habit shift,compared to those at lower latitudes.To test these two hypotheses,we modelled the proportion of deciduous broad-leaved species and the incidence of deciduous and evergreen broad-leaved species in woody angiosperm species compositions of ten largesized forest plots distributed in the Chinese subtropics.We found that the rate of leaf habit shift along a latitudinal gradient was higher in forest trees than in forest shrubs.We also found that the differentiation in leaf habit shift between trees and shrubs is greater at lower latitudes(i.e.,warmer climates)than at higher latitudes(i.e.,colder climates).These findings indicate that specialized forest plants are differentially affected by climate in distinct forest strata in a manner dependent on latitudinal distribution.These differences in forest plant response to changes in climate suggest that global climate warming will alter growth forms and geographical distributions and ranges of forests.

Biomass increment and mortality losses in tropical secondary forests of Hainan, China

Secondary forests, created after heavy logging,are an important part of China's forests. We investigated forest biomass and its accumulation rate in 38 plots in a tropical secondary forest on Hainan Island. These secondary forests are moderate carbon sinks, averaging1.96–2.17 t C ha-1 a-1. Biomass increment is largely by medium-sized(10–35 m) trees. Tree mortality accounts for almost 30% of the biomass and plays a negligible role in biomass accumulation estimates. Mortality rate is highly dependent on tree size. For small trees and seedlings, it is related to competition due to elevated irradiance after logging. Regarding prospective biomass and rates of accumulation, recovery is not as rapid as in secondary forests of cleared land. Therefore, tropical forests are susceptible to logging operations and need careful forest management.

The Spatial-Temporal Heterogeneity of Understory Light Availability in a Temperate Forest of North China

The spatial-temporal variation of understory light availability has important influences on species diversity and community assembly.However,the distribution characteristics and influencing factors of understory light availability have not been fully elucidated,especially in temperate deciduous,broad-leaved forests.In this study,the understory light availability was monitored monthly(May–October)in a temperate deciduous,broad-leaved forest in Henan Province,China.Differences in the light availability among different months and habitat types were statistically analyzed using Kruskal–Wallis method,respectively.Partial least squares path modeling(PLS-PM)was used to explore the direct and/or indirect effects of stand structure,dominant species and topographic factors on the light environment.Results showed that there were differences in light environments among the four habitat types and during the studied six months.The PLS-PM results showed that the stand structure and the dominant species were negatively correlated with the light environment,and the path coefficient values were−0.089(P=0.042)and−0.130(P=0.004),respectively.Our result indicated that the understory light availability exhibit a distinct spatial and temporal heterogeneity in temperate deciduous,broad-leaved forest of north China.The characteristics of woody plant community,especially the abundance of one of the dominant plant species,were the important factors affecting the understory light availability.

Application of SWAT99.2 to sensitivity analysis of water balance components in unique plots in a hilly region

Although many sensitivity analyses using the soil and water assessment tool(SWAT) in a complex watershed have been conducted, little attention has been paid to the application potential of the model in unique plots. In addition, sensitivity analysis of percolation and evapotranspiration with SWAT has seldom been undertaken. In this study, SWAT99.2 was calibrated to simulate water balance components for unique plots in Southern China from 2000 to 2001, which included surface runoff, percolation, and evapotranspiration. Twenty-one parameters classified into four categories, including meteorological conditions, topographical characteristics, soil properties, and vegetation attributes, were used for sensitivity analysis through one-at-a-time(OAT) sampling to identify the factor that contributed most to the variance in water balance components. The results were shown to be different for different plots, with parameter sensitivity indices and ranks varying for different water balance components. Water balance components in the broad-leaved forest and natural grass plots were most sensitive to meteorological conditions, less sensitive to vegetation attributes and soil properties, and least sensitive to topographical characteristics. Compared to those in the natural grass plot, water balance components in the broad-leaved forest plot demonstrated higher sensitivity to the maximum stomatal conductance(GSI) and maximum leaf area index(BLAI).

A two-scale approach for estimating forest aboveground biomass with optical remote sensing images in a subtropical forest of Nepal

Forests account for 80%of the total carbon exchange between the atmosphere and terrestrial ecosystems.Thus,to better manage our responses to global warming,it is important to monitor and assess forest aboveground carbon and forest aboveground biomass(FAGB).Different levels of detail are needed to estimate FAGB at local,regional and national scales.Multi-scale remote sensing analysis from high,medium and coarse spatial resolution data,along with field sampling,is one approach often used.However,the methods developed are still time consuming,expensive,and inconvenient for systematic monitoring,especially for developing countries,as they require vast numbers of field samples for upscaling.Here,we recommend a convenient two-scale approach to estimate FAGB that was tested in our study sites.The study was conducted in the Chitwan district of Nepal using GeoEye-1(0.5 m),Landsat(30 m)and Google Earth very high resolution(GEVHR)Quickbird(0.65 m)images.For the local scale(Kayerkhola watershed),tree crowns of the area were delineated by the object-based image analysis technique on GeoEye images.An overall accuracy of 83%was obtained in the delineation of tree canopy cover(TCC)per plot.A TCC vs.FAGB model was developed based on the TCC estimations from GeoEye and FAGB measurements from field sample plots.A coefficient of determination(R2)of 0.76 was obtained in the modelling,and a value of 0.83 was obtained in the validation of the model.To upscale FAGB to the entire district,open source GEVHR images were used as virtual field plots.We delineated their TCC values and then calculated FAGB based on a TCC versus FAGB model.Using the multivariate adaptive regression splines machine learning algorithm,we developed a model from the relationship between the FAGB of GEVHR virtual plots with predictor parameters from Landsat 8 bands and vegetation indices.The model was then used to extrapolate FAGB to the entire district.This approach considerably reduced the need for field data and commercial very high resolution imagery while achieving two-scale forest information and FAGB estimates at high resolution(30 m)and accuracy(R2=0.76 and 0.7)with minimal error(RMSE=64 and 38 tons ha-1)at local and regional scales.This methodology is a promising technique for cost-effective FAGB and carbon estimations and can be replicated with limited resources and time.The method is especially applicable for developing countries that have low budgets for carbon estimations,and it is also applicable to the Reducing Emissions from Deforestation and Forest Degradation(REDD?)monitoring reporting and verification processes.

STUDIES ON FOREST WATER CYCLING

Principal ideas, research approaches and installations in both Liangshui and Maoershan Ecological Stations were diseussed. Significance of comparability and synchronous detennination in research methods were stressed. Comparison analysis was done on the results gained from diferent methods. Adaptive mechanisms of Mongolian oak (Quercus mongolica) to drought and unproductive sites wer expounded through hydrological cycling studies. Surface runoff and flood peak were decreased and the developing processes of flood peak were postponed or delayed because of the presence of huge forest canopy and forest floor. However, the conclusions of forest influences on total runoff,especially in spring and in the dry season t are significant to agricultul practices in notheast China and turned out contrary for satershed sizes or different approaches, which should be studied further.

2018年浙江古田山24公顷亚热带常绿阔叶林动态监测样地林冠结构与地形数据集

林冠结构与地形因子共同影响着森林重要物种资源及生境的时空变化,而针对我国地带性森林生态系统高精度林冠结构和地形数据集极为缺乏。基于近地面遥感平台获取的激光雷达数据,可以获取精确的林冠结构和地形数据。本研究以位于钱江源国家公园核心保护区的24公顷亚热带常绿阔叶林动态监测样地为研究对象,对该区域2018年基于近地面遥感技术获取的激光雷达点云数据进行计算分析及质量控制,获取该样地的林冠结构和地形数据。通过实时动态测量(RTK)的地面数据对数字高程模型(DEM)进行精度检验和验证,表明DEM的高程中误差为0.07米,数据具有较高精度。古田山24公顷亚热带常绿阔叶林动态监测样地为典型的中亚热带低海拔常绿阔叶林,本数据集可以为亚热带常绿阔叶林生物多样性监测和研究提供数据支撑。

Assessment and Inventory of Forest Ecosystems Biodiversity: Case Study for Karelian Isthmus of Leningrad Region, Russia

Regular grid of permanent sample plots (PSP) of ICP-Forests monitoring system was used for forest ecosystems biodiversity assessments and inventory. The supplementary features were added to the PSP structure to conduct biological diversity census: eight sample plots 1 × 1 m for geo-botanical description;two sample plots of 5 × 5 m each for description of the PSP’s undergrowth;one 25 × 25 m plot for coarse woody debris estimations;four soil inventory pits. The total number of PSP amounted to 248. Total data used are as following: 1) 1984 geo-botanical descriptions of vegetation belonging to ground cover layers made on 1 × 1 m sample plots;2) 496 descriptions of undergrowth on 5 × 5 m sample plots;3) 178 descriptions of woody debris on 25 × 25 m sample plots;4) 496 descriptions of soil inventory pits. General statistical indicators characterizing forest land cover diversity were calculated. Statistic indicators of α-diversity for the Karelian Isthmus forest vegetation cover have the following values: 1) m (mean number of species per PSP) = 26 species;2) σ (standard deviation) = 9.5 species;3) v (variation coefficient) = 36.5%;4) Р (deviation amplitude) = 60 – 7 = 53 species. β – diversity of forest ecosystems as well as γ – diversity also was studied on the base of information collected on the same regular grid of sample plots. It appears that sample plots distribution by species diversity gradation is well described by the standard curve of normal distribution for the entire Karelian Isthmus forest (determination coefficient of the curve being 95.2%) as well as for each type of forest. Hence, the criterion (standard) of biodiversity for forest ecosystems can be defined as the mean value of alpha diversity for each forest type group – m;and the standard deviation – σ, as a tool for assessing deviations from the standard. PSP locations are fixed using GPS technology, this allows biodiversity assessments at the same place in the next years for biodiversity trends estimations and consist the frame for systematic biodiversity inventory.

神农架南坡小叶青冈+曼青冈常绿阔叶林物种组成与群落结构

本研究在神农架南坡建立1 hm2的常绿阔叶林动态监测固定样地,分析了该群落的物种组成、区系特征、垂直结构、径级结构和空间分布格局。结果显示,群落物种丰富,共调查到维管植物216种,隶属78科154属,其中胸径≥1 cm的木本植物38科69属107种。区系成分中,热带分布的科、属分别占总科、属数的50.00%和40.58%;温带分布的科、属分别占总科、属数的34.21%和53.63%。常绿树种占比55.14%(59种),落叶树种占比44.86%(48种),其中常绿树种的多度、胸高断面积和重要值占比分别为82.23%、64.79%和73.03%。偶见种占比33.64%(36种),稀有种占比8.41%(9种)。群落垂直结构明显,可分为乔木层、灌木层和草本层,各个层次物种丰富。径级结构呈倒“J”型,属于增长型群落。优势种的空间分布呈现出不同程度的聚集分布。研究表明,该群落的常绿树种重要值明显高于落叶树种,属于小叶青冈(Cyclobalanopsis myrsinifolia Blume)+曼青冈(Cyclobalanopsis oxyodon Miq.)群系,是该区域代表性的常绿阔叶林。区系成分体现出神农架作为中亚热带和北亚热带分界线的特征。群落有着较好的更新能力,呈现向常绿阔叶林顶极群落演替的趋势。

机器学习对H.pylori感染患者的特征变量及预测模型研究

目的 分析H.pylori感染患者感染的危险因素,建立H.pylori感染患者预测模型,为防治H.pylori感染提供参考。方法 选取2021年7至2022年5月在中山市中医院、中山市东凤人民医院、中山市南区医院共1 477例接受H.pylori检测者为研究对象,依据胃镜和~(14)C、~(13)C呼气试验的检测结果,将H.pylori受检人群分为感染组和无感染组,分别进行问卷调查,调查内容包括受检者基本情况、临床表征、慢性基础病、生活和饮食习惯等,共计63个变量。采用单因素及机器学习中的Logistic回归、决策树分析及添加交互项的Logistic回归对H.pylori感染进行多因素分析,并比较3个模型的ROC曲线下的面积、灵敏度、特异度,验证模型的准确性,建立H.pylori感染预测模型,将特征和危险因素建立森林图。结果 Logistic回归分析的AUC为0.7361,灵敏度为0.7615,特异度为0.6034。决策树分析的AUC为0.6528,灵敏度为0.6801,特异度为0.5773。添加交互项后的Logistic回归分析的AUC为0.7388,灵敏度为0.7588,特异度为0.6034。添加交互项的多因素Logistic回归结果显示,有胃胀,口气、口臭,在家煮食午餐,在家无而外出有使用公筷习惯,同居家人有感染,疫情后才使用公筷,居住4~10层楼,同时有胃胀及口气、口臭为模型的显著性变量。结论 胃胀,有口气、口臭,同时有胃胀及口气、口臭,在家煮食午餐,居住的楼层数,外出居家是否使用公筷,是否有使用公筷习惯,家人是否感染H.pylori是感染H.pylori的特征因素,用Logistic回归模型作为主模型进行变量筛选,添加交互后的模型,AUC有所提升,交互项的预测模型对H.pylori感染者预判能力好,运算容易,使用经济、便利,适合区域性推广。

祁连山国家公园青海片区森林大样地生物多样性特征

【目的】通过监测森林大样地植物群落特征的长期动态变化,揭示物种多样性空间格局及维持机制,为该区域的生物多样性保护提供科学依据。【方法】以祁连山区青海云杉林生态系统为研究对象,采用相邻格子法进行大样地乔木植株每木调查,并解析其生物多样性调控因素。【结果】青海云杉林生态系统的乔木总数为35835株,青海云杉和祁连圆柏分别占据57.84%和23.82%。物种丰富度和平均株高分别为3种和10.7 m。Shannon-Wiener指数和Simpson指数分别为0.74和0.43,Shannon-Wiener指数偏低,但Simpson指数较高,存在物种数量集中度较高现象。森林大样地Shannon-Wiener受乔木高度、物种丰富度和Simpson指数的极显著影响。机器学习模型训练集和测试集的决定系数分别为0.95和0.93,均方根误差分别为0.06和0.08,表明模型对Shannon-Wiener指数的解释能力和预测精度均较高。【结论】青海云杉林物种多样性较低且受乔木高度、物种丰富度和Simpson指数的显著影响,其对维持该区域的生物多样性具有重要作用。

慢性肾衰竭血液透析患者发生导管相关性血流感染的Nomogram预测模型构建

目的 分析慢性肾衰竭(CRF)血液透析患者发生导管相关性血流感染(CRBSI)的影响因素,并构建Nomogram预测模型。方法 选取行血液透析的120例CRF患者为研究对象。根据是否发生CRBSI,分为CRBSI组(n=19)和非CRBSI组(n=101)。比较2组临床资料、生物学标志物[外周血白蛋白(ALB)、血清降钙素原(PCT)、肿瘤坏死因子-α(TNF-α)、白细胞介素-8(IL-8)、转化生长因子-β1(TGF-β1)、Smad指标(Smad2、Smad3)]水平。分析CRF血液透析患者发生CRBSI的影响因素。根据影响因素构建CRF血液透析患者发生CRBSI的Nomogram预测模型,并采用受试者工作特征(ROC)曲线、校准曲线、决策曲线分析(DCA)对该模型进行验证。结果 120例CRF血液透析患者中,发生CRBSI 19例,发生率为15.83%。CRBSI组的年龄、吸烟占比、合并糖尿病占比、急性生理与慢性健康状况评分系统Ⅱ(APACHEⅡ)评分以及血清PCT、TNF-α、IL-8、TGF-β1、Smad2和Smad3水平高于非CRBSI组,外周血ALB水平低于非CRBSI组,差异有统计学意义(P<0.05);CRBSI组的插管次数、导管留置时间多于或长于非CRBSI组,差异有统计学意义(P<0.05)。Logistic分析显示,吸烟、年龄、导管留置时间、插管次数、APACHEⅡ评分、合并糖尿病、PCT、IL-8、ALB、TGF-β1、Smad2、TNF-α和Smad3是CRF血液透析患者发生CRBSI的影响因素(P<0.05);森林图结果显示,年龄、吸烟、插管次数、导管留置时间、合并糖尿病、APACHEⅡ评分、PCT、TNF-α、IL-8、TGF-β1、Smad2、Smad3水平均为正相关因素,ALB水平为负相关因素(P<0.05)。ROC曲线、校准曲线、DCA显示,构建的CRF血液透析患者发生CRBSI风险的Nomogram预测模型具有良好一致性和预测效能。结论 年龄、插管次数、吸烟、导管留置时间、APACHEⅡ评分、PCT、合并糖尿病、ALB、TNF-α、TGF-β1、Smad2、IL-8和Smad3是CRF血液透析患者发生CRBSI的影响因素。基于上述因素构建的Nomogram预测模型具有良好预测价值。

RTK与罗盘仪在林草生态综合监测森林样地调查中的效率比较

作为卫星差分定位及实时处理的新型测量方法,RTK技术在广西近年的林草生态综合监测森林样地调查中已初步得到应用,本文分别运用RTK和罗盘仪测量方法进行调查比较,阐明2种仪器在样地调查测量中的效率及其优劣性。结果表明:RTK测量方法的应用精度及使用效率优势明显,为拓展其在林业调查中的应用提供参考。