Geographic patterns of taxonomic and phylogenetic β-diversity of aquatic angiosperms in China

China covers a vast territory harbouring a large number of aquatic plants.Although there are many studies on the β-diversity of total,herbaceous or woody plants in China and elsewhere,few studies have focused on aquatic plants.Here,we analyse a comprehensive data set of 889 aquatic angiosperm species in China,and explore the geographic patterns and climatic correlates of total taxonomic and phylogeneticβ-diversity as well as their turnover and nestedness components.Our results show that geographic patterns of taxonomic and phylogenetic β-diversity are highly congruent for aquatic angiosperms,and taxonomic β-diversity is consistently higher than phylogenetic β-diversity.The ratio between the nestedness component and total β-diversity is high in northwestern China and low in southeastern China.The geographic patterns of taxonomic and phylogenetic β-diversity of aquatic angiosperms in China are obviously affected by geographic and climatic distances,respectively.In conclusion,the geographic patterns of taxonomic and phylogenetic β-diversity of aquatic angiosperms are consistent across China.Climatic and geographic distances jointly affect the geographic patterns of β-diversity of aquatic angiosperms.Overall,our work provides insight into understanding the large-scale patterns of aquatic angiosperm β-diversity,and is a critical addition to previous studies on the macroecological patterns of terrestrial organisms.

β-diversity Patterns of Plant Community in Fragmented Habitat in a Degenerated Meadow in Songnen Plain,China

A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 2007. These islands were classified as large, medium, and small scales on the basis of the island area （100-1000m2, large island; 50-100m2, middle island; 10-50m2, small island）. Each scale of the investigation involved eight islands. The responses ofβ-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands. The results indicated that at the local community level, there were 57 species belonging to 20 families and 49 genera in large islands, 49 species belonging to 16 families and 40 genera in middle islands, and 27 species belonging to eight families and 23 genera in small islands, β-diversity indexes for species, genus and family in large, middle, and small islands varied greatly, and the highest value of the indexes was not noted in the largest island. However, the average of the data obtained at the three scales showed that across large islands, Whittaker indexes were low and Bray-Curtis similarity indexes were high, while across small islands, Whittaker indexes were high and Bray-Curtis similarity indexes were low. At the metacommunity level, Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation （p〈0.01） with the island area, whereas the Bray-Curtis indexes for species, genus and family showed a great significantly positive double logarithmic correlation （p〈0.01） with the island area. At both local community and metacommunity levels, tumovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family. Hence, the species and the genus could be used for the analysis offl-diversity patterns of plant community.

Global comparisons of beta diversity among mammals,birds,reptiles,and amphibians across spatial scales and taxonomic ranks

Beta diversity is the change in species composition among areas in a geographic region. The proportion of species shared between two areas often decreases when the distance separating them increases, leading to an increase in beta diversity. This study compares beta diversity among four classes of terrestrial vertebrates （mammals, birds, reptiles, and amphibians） at both regional （biogeographic realm） and global extents, using the same sets of faunal sample units for all four groups in each comparison. Beta diversity is lower for the two endothermic taxa （birds and mammals） than for the two ectothermic taxa （reptiles and amphibians） in all six biogeographic realms examined. When the four taxa in the six biogeographic realms are combined, beta diversity at the species rank is higher than that of the genus rank by a factor of 1.24, and is higher than that of the family rank by a factor of 1.85. The ratio of beta diversity at the genus rank to that at the family rank is 1.50. Beta diversity is slightly higher for ecoregions of 5000-99,999 km^2 than for ecoregions of 100,000-5,000,000 km^2.

Relationship between diversity of forest plant species and environmental gradient in eastern mountainous area of Heilongjiang Province, China

Twenty-three secondary forest communities with different structure were selected in Mao＇er Mountain National Park of Heilongjiang Province, China to study the relationship between diversity of forest plant species and environmental gradient. The forest plant species diversity was analyzed by the diversity index, and the environmental factors was quantified by the method of Whittaker＇s quantification of environmental gradient. Meanwhile, β-diversity indexes of communities were calculated with similar measurements. The results showed that the Shannon-wiener diversity index of forest plant species increased with the increase of the environmental gradient, and the β-diversity indexes of communities showed a liner increase along with the change of environmental gradient.

Current climate overrides past climate change in explaining multi-site beta diversity of Lauraceae species in China

Background:We aimed to characterise the geographical distribution of Sørensen-based multi-site dissimilarity(β_(sor))and its underlying true turnover(β_(sim))and nestedness(βsne)components for Chinese Lauraceae and to analyse their relationships to current climate and past climate change.Methods:We used ensembles of small models(ESMs)to map the current distributions of 353 Lauraceae species in China and calculated β_(sor) and its β_(sim) and β_(sne) components.We tested the relationship between β_(sor),β_(sne) and β_(sim) with current climate and past climate change related predictors using a series of simultaneous autoregressive(SAR_(err))models.Results:Spatial distribution of β_(sor)of Lauraceae is positively correlated with latitude,showing an inverse rela-tionship to the latitudinalα-diversity(species richness)gradient.High β_(sor) occurs at the boundaries of the warm temperate and subtropical zones and at the Qinghai-Tibet Plateau due to high β_(sne).The optimized SAR_(err) model explainsβ_(sor) andβ_(sne) well,but notβ_(sim).Current mean annual temperature determinesβ_(sor) and β_(sne) of Lauraceae more than anomalies and velocities of temperature or precipitation since the Last Glacial Maximum.Conclusions:Current low temperatures and high climatic heterogeneity are the main factors explaining the high multi-siteβ-diversity of Lauraceae.In contrast to analyses of the β-diversity of entire species assemblages,studies of single plant families can provide complementary insights into the drivers of β-diversity of evolutionarily more narrowly defined entities.

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.

Plant functional and phylogenetic turnover correlate with climate and land use in the Western Swiss Alps

Aims Understanding the relative importance of historical and environ-mental processes in the structure and composition of communities is one of the longest quests in ecological research.Increasingly,researchers are relying on the functional and phylogeneticβ-diversity of natural communities to provide concise explanations on the mechanistic basis of community assembly and the drivers of trait variation among species.The present study investigated how plant functional and phylogeneticβ-diversity change along key environmental and spatial gradients in the Western Swiss Alps.Methods Using the quadratic diversity measure based on six functional traits-specific leaf area,leaf dry matter content,plant height,leaf carbon content,leaf nitrogen content and leaf carbon to nitrogen content alongside a species-resolved phylogenetic tree-we relate variations in climate,spatial geographic,land use and soil gradients to plant functional and phylogenetic turnover in mountain commu-nities of the Western Swiss Alps.Important Findings Our study highlights two main points.First,climate and land-use factors play an important role in mountain plant community turnover.Second,the overlap between plant functional and phy-logenetic turnover along these gradients correlates with the low phylogenetic signal in traits,suggesting that in mountain land-scapes,trait lability is likely an important factor in driving plant community assembly.Overall,we demonstrate the importance of climate and land-use factors in plant functional and phyloge-netic community turnover and provide valuable complementary insights into understanding patterns ofβ-diversity along several ecological gradients.

The relative and combined effects of herbivore assemblage and soil nitrogen on plant diversity

Plant diversity can be affected by both herbivore grazing and soil resources. However, it is unclear if the joint effects of herbivores and soil resources might vary with components of plant diversity. Here, we evaluated the relative and combined effects of herbivore assemblage and soil nitrogen(N) quantity and heterogeneity on the α and β components of plant diversity in a grassland that was subjected to four years of grazing under differing herbivore assemblages(no grazing, cattle grazing, sheep grazing, and mixed grazing). We found that herbivore assemblage combined with soil N quantity explained 41% of the variation in plant α-diversity, while herbivore assemblage combined with soil N heterogeneity explained 15% of the variation in plant β-diversity. The independent effects of herbivore assemblage explained more than those of soil N for both α-and β-diversity(α-diversity: 12% vs. 4%;β-diversity: 18% vs. 16%). We concluded that the effects of herbivores are stronger than those of soil N,and that grazing-induced changes in soil resources are important drivers of plant diversity change, especially α-diversity.Therefore, we suggest that managing herbivore species by accounting for the effects that their grazing can have on soil resources may be significant for plant diversity maintenance.

Vertical stratification of ichneumonid wasp communities： the effects of forest structure and life-history traits

Parasitoid wasp communities of the canopy of temperate forests are still largely unexplored. Very little is known about the community composition ofparasitoids between canopy and understory and how much of this difference is related to forest structure or parasitoid biological strategies. In this study we investigated upon the difference in the community composition of the parasitic wasps Ichneumonidae between canopy and understory in a lowland temperate forest in northern Italy. We used general linear models to test whether parasitic strategy modifies species vertical stratification and the effect of forest structure. We also tested differences in β-diversity between canopy and understory traps and over time within single forest layers. We found that stand basal area was positively related to species richness, suggesting that the presence of mature trees can influence local wasp diversity, providing a higher number of microhabitats and hosts. The ichneumonid community of the canopy was different from that of the understory, and theβ-diversity analysis showed higher values for the canopy, due to a higher degree of species turnover between traps. In our analyses, the vertical stratification was different between groups of ichneumonids sharing different parasitic strategies. Idiobiont parasitoids of weakly or deeply concealed hosts were more diverse in the understory than in the canopy while parasitoids of spiders were equally distributed between the two layers. Even though the ichneumonid community was not particularly species-rich in the canopy of the temperate forests, the extension of sampling to that habitat significantly increased the number of species recorded.

Diversity patterns, environmental drivers and changes in vegetation composition in dry inter-Andean valleys

Aims We studied diversity,patterns of endemism and turnover of veg-etation composition in dry inter-Andean valleys(DIAVs)where lit-tle is known about the influence of the abiotic drivers controlling plant species composition and occurrences,and the life forms that contribute most toα-andβ-diversity,respectively.This study was focused on DIAVs located in the highlands(800-2800 m)around the Equator(1°N-5°S).The following questions were addressed:(i)what differences exist between endemic and non-endemic species in terms of species number,frequency and abundance?(ii)are pat-terns ofα-andβ-diversity correlated with latitude?(iii)what are the major environmental drivers controlling spatial patterns in species composition and occurrence?Methods We established 63 transects of 5×100 m in areas with DIAV vegetation,impacted as little as possible by human activities.In each transect,all mature trees and shrubs were identified and counted to determine their density.The coverage of terrestrial herbs was estimated.Generalized additive models were used to quantify the relationship betweenα-andβ-diversity with latitude.To recordα-diversity,we used the exponential Shannon index.The Sørensen index was used to measureβ-diversity or species turnover.We used canonical correspondence analysis to deter-mine species composition and generalized linear mixed models to quantify simultaneously the determinants of species occur-rence across species and sites.The models were evaluated using the Akaike information criterion.All analyses were run separately for trees,herbs and shrubs.Important Findings Overall,we found that shrubs was the most diverse life form,constituting 43%(12%endemic)of the 313 species,followed by herbs(36%;11.5%endemic)and trees(20%;5%endemic).Trees comprise mostly species with low abundance(e.g.<3 individuals ha^(−1)),which was also true for herbs,whereas shrubs showed a larger number of abundant species(>30 individuals ha^(−1)),includ-ing four endemic species.Most of the endemic species were locally rare,and most of them were restricted to southern valleys,suggesting low migration rates due to local barriers.We identified seven species distribution patterns that gave rise to high β-diversity in the dry inter-Andean valleys.Theβ-diversity of trees was the lowest.Herbs had the highestβ-diversity,which increased steadily with geographic distance.Our results further highlight the influ-ence of disturbance,water availability and low temperature on plant species composition and occurrence.We also found signifi-cant,contrasting patterns in responses to environmental drivers,when analyzing our data separately by life form.Our results show that analyzing diversity patterns separately by life form can shed new light on the mechanisms that have generated present-day pat-terns of plant diversity in DIAVs.

Response of reed community to the environment gradientwater depth in the Yellow River Delta, China

We investigated and monitored a reed community in the fields.Data on the bio-ecological characteristics and β-diversity of reed communities in different environmental gradients(mainly based on water depth)of the Yellow River Delta were collected through multianalysis,extremum analysis and β-diversity index analysis.In accordance with the square sum of deviations(Ward)cluster analysis,10 sampling plots were divided into six types with the dominant plants in different plots varying according to the change in environmental gradients.The dominant plants in these plots varied from aquatic plants to xerophytes and salt tolerant plants as water depth decreased.The average height and diameter of the reeds at breast level were significantly correlated with the average water depth.The fitness curves of average density and coverage with average water depth were nonlinear.When the average water depth was 0.3 m,the average density and coverage of reeds reached the apex value,while the height and diameter of the reeds at breast level increased with the water depth.There were obvious changes to the environmental gradient in the Yellow River Delta.The transitional communities were also found to exist in the Yellow River Delta by β-diversity analysis.Vicarious species appeared with the change in water depth.The occurrence of substitute species is determined by the function of common species between adjacent belts.The different functions of common species led to differences in community structure and function and differences in dominant plants.The result reflects the variations of species present in different habitats and directly reflects environmental heterogeneity.The values of β-diversity indices of adjacent plots were higher than those of nonadjacent plots.There are transition zones between the xerophytes and aquatic plants in the Yellow River Delta.In an aquatic environment,the similarity of reed community is higher than that of xeromorphic plants.The β-diversity index can reflect plant succession trends caused by the change in environmental gradients in the Yellow River Delta.The β-diversity index reveals plant responses to changes in environmental gradient and is helpful in observing changes in patterns of species diversity in relation to environmental gradient change and evolving trends in the future,which in turn plays a prominent role when environmental water requirements of wetland are discussed.

Niacin alters the ruminal microbial composition of cattle under high-concentrate condition

To understand the effects of niacin on the ruminal microbial ecology of cattle under high-concentrate diet condition, Illumina MiSeq sequencing technology was used. Three cattle with rumen cannula were used in a 3 x 3 Latin-square design trial. Three diets were fed to these cattle during 3 periods for 3 days, respectively: high-forage diet(HF; forage-to-concentrate ratio = 80:20), high-concentrate diet(HC;forage-to-concentrate ratio=20:80), and HC supplemented with 800 mg/kg niacin(HCN). Ruminal pH was measured before feeding and every 2 h after initiating feeding. Ruminal fluid was sampled at the end of each period for microbial DNA extraction. Overall, our findings revealed that subacute ruminal acidosis(SARA) was induced and the a-diversity of ruminal bacterial community decreased in the cattle of HC group. Adding niacin in HC could relieve the symptoms of SARA in the cattle but the ruminal pH value and the Shannon index of ruminal bacterial community of HCN group were still lower than those of HF group. Whatever the diet was, the ruminal bacterial community of cattle was dominated by Bacteroidetes,Firmicutes and Proteobacteria. High-concentrate diet significantly increased the abundance of Prevotella,and decreased the abundance of Paraprevotella, Sporobacter, Ruminococcus and Treponema than HF.Compared with HC, HCN had a trend to decrease the percentage of Prevotella, and to increase the abundance of Succiniclasticum, Acetivibrio and Treponema. Increasing concentrate ratio could decrease ruminal pH value, and change the ruminal microbial composition. Adding niacin in HC could increase the ruminal pH value, alter the ruminal microbial composition.

the National Natural Science Foundation of China(41877029,41961130383);Royal SocietyNewton Advanced Fellowship(NAF\R1\191017);Wuhan Science and Technology Bureau(2019020701011469).

Due to the tremendous diversity of microbial organisms in topsoil,the estimation of saturated richness in a belowground ecosystem is still challenging.Here,we intensively surveyed the 16S rRNA gene in four 1 m2 sampling quadrats in a typical grassland,with 141 biological or technical replicates generating over 11 million sequences per quadrat.Through these massive data sets and using both non-asymptotic extrapolation and non-parametric asymptotic approaches,results revealed that roughly 15919±193,27193±1076 and 56985±2347 prokaryotic species inhabited in 1 m2 topsoil,classifying by DADA2,UPARSE(97%cutoff)and Deblur,respectively,and suggested a huge difference among these clustering tools.Nearly 500000 sequences were required to catch 50%species in 1 m2,while any estimator based on 500000 sequences would still lose about a third of total richness.Insufficient sequencing depth will greatly underestimate both observed and estimated richness.At least~911000,~3461000,and~1878000 sequences were needed for DADA2,UPARSE,and Deblur,respectively,to catch 80%species in 1 m2 topsoil,and the numbers of sequences would be nearly twice to three times on this basis to cover 90%richness.In contrast,α-diversity indexes characterized by higher order of Hill numbers,including Shannon entropy and inverse Simpson index,reached saturation with fewer than 100000 sequences,suggesting sequencing depth could be varied greatly when focusing on exploring differentα-diversity characteristics of a microbial community.Our findings were fundamental for microbial studies that provided benchmarks for the extending surveys in large scales of terrestrial ecosystems.

Alterations in gut microbiota and physiological factors associated with abdominal aortic aneurysm

Abdominal aortic aneurysm(AAA)is a progressive focal dilatation and weakening of the abdominal aorta,causing 1.3%of all deaths among men aged 65–85 years worldwide.The formation of AAA is a complex process with multiple risk factors.Therefore,this study aimed to determine the relationship of disease severity and physiological factors,and gut microbiota structures in AAA patients.Physiological indicators and fecal 16S rRNA gene sequences from healthy controls and patients with AAA were collected.The correlations between the diameter of the AAA and clinical parameters,and gut microbiota composition were then analyzed separately using multivariable analysis.The diameter of AAA was extremely positively correlated with smoking index,alkaline phosphatase,blood glucose,and blood triglycerides and negatively correlated with prealbumin and Cystatin C.As the diameter of AAA increased,the α-diversity,including Chao 1,Shannon,and Simpson indices,of the gut microbiota decreased and presented a negative linear relationship.Patients with AAA with more severe disease had significantly increased relative abundance of Enterobacteriaceae and decreased relative abundance of Veillonellaceae.A strong correlation was observed between the diameter and physiological data,as well as between diameter and gut microbiota composition.This study could improve the understanding of AAA,and gut microbiota may be a potential target to prevent and treat this deadly disease.