Host plant traits play a crucial role in shaping the composition of epiphytic microbiota in the arid desert,Northwest China

Phyllosphere microorganisms are a crucial component of environmental microorganisms,highly influenced by host characteristics,and play a significant role in plant health and productivity.Nonetheless,the impact of host characteristics on shaping phyllosphere microbial communities of plants with different life forms remains ambiguous.Utilizing high-throughput sequencing technology,this study analyzed the diversity and community composition of phyllosphere epiphytic microorganisms(e.g.,bacteria and fungi)of various plant life forms in the hinterland of the Gurbantunggut Desert,Northwest China.Functional annotation of prokaryotic taxa(FAPROTAX)and fungi function guild(FUNGuild)were employed to assess the ecological functions of microorganisms and to investigate the role of stochastic and deterministic processes in shaping phyllosphere microbial communities.Result showed a diverse array of phyllosphere epiphytic microorganisms in the desert plants,with Proteobacteria,Cyanobacteria,and Actinobacteriota dominating bacterial community,while Ascomycota and Basidiomycota were prevalent in fungal community.Comparison across different plant life forms highlighted distinct microbial communities,indicating strong filtering effects by plant characteristics.FAPROTAX prediction identified intracellular parasites(accounting for 27.44%of bacterial community abundance),chemoheterotrophy(10.12%),and phototrophy(17.41%)as the main functions of epiphytic bacteria on leaves of different life form plants.FUNGuild prediction indicated that phyllosphere epiphytic fungi primarily served as Saprotrophs(81.77%),Pathotrophs(17.41%),and Symbiotrophs(0.82%).Co-occurrence network analysis demonstrated a predominance of positive correlations among different microbial taxa.Raup-Crick dissimilarity index analysis revealed that deterministic processes predominantly influenced phyllosphere bacterial and fungal community assembly.Variance partitioning analysis and random forest modeling suggested that plant leaf functional traits significantly impacted both bacterial and fungal community composition,with fungal community composition showing a closer association with leaf nutrients and physiology compared with bacterial community composition.The distinct responses of bacterial and fungal communities to plant traits were attributed to the differing properties of bacteria and fungi,such as bacteria having higher potential dispersal rates and broader ecological niches than fungi.Overall,the results indicate that phyllosphere bacterial and fungal communities undergo similar community assembly processes,with fungi being more influenced by plant characteristics than bacteria.These findings offer novel insights into the ecology of phyllosphere microbial communities of desert plants.

Variations of plant life form diversity along the Northeast China Transect and its direct gradient analysis

Plant life form diversity and its direct gradient analysis on a larger scale climate change gradient were tested, based on the data from Northeast China Transect platform. The results showed that the species numbers, life form richness and life form diversity were relative higher at the eastern forests and the ecotone between typical vegetation, while those on the meadow grasslands and typical steppes were lower. Although plant life forms can reflect the climate variations, life form diversity is not consistent with the major global gradient along the NECT.

Impacts of snow on seed germination are independent of seed traits and plant ecological characteristics in a temperate desert of Central Asia

Seed germination profoundly impacts plant community composition within the plant life cycle.Snow is an important source of water for seed germination in the temperate deserts of Central Asia.Understanding how seed germination responds to variations in snow cover in relation to seed traits and plant ecological characteristics can help predict plant community sustainability and stability in Central Asia under a scenario climate change.This study investigated the seed germination of 35 plant species common to the Gurbantunggut Desert in Central Asia under the three snow treatments:(1)snow addition;(2)ambient snow;and(3)snow removal.Two-way analysis of variance(ANOVA)tests were performed to assess interactions among the impacts of snow treatments,seed traits and plant ecological characteristics on seed germination.Phylogenetic generalized least-squares(PGLS)model was used to test the relationships between seed traits and seed germination.The results demonstrated that snow variations had no significant impacts on seed germination overall.Seed germination under the snow addition treatment was similar with that under the ambient snow treatment,irrespective of seed traits and plant ecological characteristics.Snow removal only had negative impacts on seed germination for certain groups of seed traits and plant ecological characteristics.Seed mass positively affected seed germination,showing a linear increase of arcsin square root-transformed seed germination with log-transformed seed mass.Seed shape also profoundly impacted seed germination,with a higher germination percentage for elongated and flat seeds.Seed germination differed under different plant life forms,with semi-shrub species showing a significantly higher germination percentage.Most importantly,although snow treatments,seed traits and plant ecological characteristics had no interactive effects on seed germination overall,some negative impacts from the snow removal treatment were detected when seeds were categorized on the basis of seed mass and shape.This result suggests that variations of snow cover may change plant community composition in this temperate desert due to their impacts on seed germination.

Species-area relationship within and across functional groups at alpine grasslands on the northern Tibetan Plateau,China

The species-area relationship （SAR） is one of the most fundamental concepts in community ecology and is helpful for biodiversity conservation. However, few studies have systematically addressed this topic for different alpine grassland types on the Tibetan Plateau, China. We explored whether the plant composition of different functional groups affects the manner in which species richness inereases with increasing area at scales ≤ 1.0 m^2. We also compared species richness （S） within and across forbs, legumes, sedges and grasses, with sampling subplot area （A） increasing from 0.0625 m^2 to 1.0 m^2 between alpine meadow and steppe communities. We applied a logarithmic function （S = b0 ＋ b1 ln A） to determine the slope and intercept of SAR curves within and across functional groups. The results showed that the logarithmic relationship holds true between species richness and sampling area at these small scales. Both the intercept and slope of the logarithmic forbs-area curves are significantly higher than those for the three other functional groups （P 〈 0.05）. Forb accounts for about 91.9 % of the variation in the intercept and 75.0% of the variation in the slope of the SAR curve when all functional groups＇ data were pooled together. Our results indicated that the different SAR patterns should be linked with species dispersal capabilities, environmental filtering, and life form composition within alpine grassland communities. Further studies on the relationship between species diversity and ecosystem functions should specify the differential responses of different functional groups to variations in climate and anthropogenic disturbances.

Environmental heterogeneity regulates species-area relationships through the spatial distribution of species

Species-area relationships(SARs),also known as species-area curves,are fundamental scaling tools for biodiversity research.Sampling design and taxonomic groups affect the widely cited forms of species-area curves.However,the influence of sampling design and related environmental heterogeneity on SAR curves is rarely considered.Here,we investigated the SAR among different plant life forms(herbaceous plants,shrubs,and trees)in a 25.2-ha ForestGEO plot,the Wanglang Plot,in Sichuan,southwestern China,using a non-contiguous quadrat sampling method and power-law model.We compared the estimated parameters(the intercept c and the slope z)of the power-law models among different plant life forms,tested whether the SAR curve forms varied with sampling starting location,and assessed the effect of environmental heterogeneity accumulating with sampling area on curve variation.We found a wider range of variations in the SARs.The estimated c,z-values of power SAR were higher for the herbaceous plants than for the woody plants.A wider variation of SARs for the herbaceous plants than those for the woody plants.The selection of sampling starting location affected the SAR curve forms because of the roles of soil and topographic heterogeneity.We concluded that environmental heterogeneity regulates SAR curves sampled from different starting locations through spatial distribution of plant life forms.Thus,we recommend considering the design of sampling starting location when constructing SAR curves,especially in a heterogeneous habitat with unrandom distribution patterns of species.

Variation and adaptation in leaf sulfur content across China

Sulfur is an essential functional element in leaves,and it plays important roles in regulating plant growth,development and abiotic stress resistance in natural communities.However,there has been limited information on the spatial variation in leaf sulfur content(LSC)and adaptive characters on a large community scale.Sulfur in leaves of 2207 plant species from 80 widespread ecosystems(31 forests,38 grasslands and 11 deserts)in China was measured.One-way analysis of variance with Duncan’s multiple-range tests were used to evaluate the differences in LSC among different plant growth forms and ecosystems.We fitted the relationships of LSC to spatial and climate factors using regression.Structural equation modeling analysis and phylogenetic analysis helped us further explore the main factors of LSC variation.LSC ranged from 0.15 to 48.64 g·kg^(-1),with an average of 2.13±0.04 g·kg^(-1) at the community scale in China.We observed significant spatial variation in LSC among different ecosystems and taxa.Overall,LSC was higher in arid areas and herbs.Furthermore,higher LSC was observed under environments of drought,low temperatures and intense ultraviolet radiation.Temperature,precipitation,radiation,soil sulfur content and aridity jointly regulated LSC,explaining 79%of the spatial variation.However,LSC was not significantly related to phylogeny.Our results demonstrate that LSC plays an important role in plant adaptations to extreme environments and further extend our understanding of the biological function of sulfur from the organ to the community level.These findings highlight the importance of sulfur metabolism for our understanding of the impact of global climate change on plants.

Vegetation composition of old extensive green roofs(from 1980s Germany)

Introduction:Since their development in the late 1970s in Germany,extensive green roofs(EGR)have become increasingly popular as mitigation tools for urban environmental issues around the world.EGRs are planted with select species,which ensure consistent cover and performance over time.This research presented herein is part of a systematic re-evaluation of EGR technology since the German industry began.Methods:Given the opportunity to access a small sample of old EGRs installed over 20 years ago in south-west Germany,this research surveyed the vegetation and substrate with an interest in describing these parameters with time-through-space substitution.Results:Similar to previous studies,this preliminary work found correlations between roof age with vegetation(cover abundance and species diversity)and substrate properties(e.g.,depth,organic content,pH,and nutrients).Roof age had positive relationship with soil organic content(Corg),and negative relationships with substrate depth and soil pH.These soil variables are inter-related,as shallow acidic substrates create unfavourable conditions for decomposition and thereby the accumulation of duff.Substrate variables correlated with EGR vegetation,suggesting a trend of simplified species composition over time.Indeed,Corg had a negative relationship with cover and species diversity of most life forms;only Sedum species had positive associations with Corg.Conclusions:Considering the dynamics associated with shallow mineral substrates,and the greater floristic diversity of younger roofs,simple Sedum-based vegetation may represent a steady state for conventional EGRs.

Effect of shrub encroachment on leaf nutrient resorption in temperate wetlands in the Sanjiang Plain of Northeast China

Background:Nutrient resorption is an important plant nutrient conservation strategy in wetlands.However,how shrub encroachment alters plant nutrient resorption processes is unclear in temperate wetlands.Here,we collected green and senesced leaves of common sedge,grass,and shrub species in wetlands with high(50–65%)and low(20–35%)shrub covers in the Sanjiang Plain of Northeast China,and assessed the impact of shrub encroachment on leaf nitrogen(N)and phosphorus(P)resorption efficiency and proficiency at both plant growth form and community levels.Results:The effects of shrub cover on leaf nutrient resorption efficiency and proficiency were identical among shrubs,grasses,and sedges.Irrespective of plant growth forms,increased shrub cover reduced leaf N resorption efficiency and proficiency,but did not alter leaf P resorption efficiency and proficiency.However,the effect of shrub cover on leaf nutrient resorption efficiency and proficiency differed between plant growth form and community levels.At the community level,leaf N and P resorption efficiency decreased with increasing shrub cover because of increased dominance of shrubs with lower leaf nutrient resorption efficiency over grasses and sedges.Accordingly,community‑level senesced leaf N and P concentrations increased with elevating shrub cover,showing a decline in leaf N and P resorption proficiency.Moreover,the significant relationships between leaf nutrient resorption efficiency and proficiency indicate that shrub encroachment increased senesced leaf nutrient concentrations by decreasing nutrient resorption efficiency.Conclusions:These observations suggest that shrub encroachment reduces community‑level leaf nutrient resorp‑tion efficiency and proficiency and highlight that the effect of altered plant composition on leaf nutrient resorption should be assessed at the community level in temperate wetlands.

Plant traits related to leaf decomposition processes in arid ecosystems of northern Patagonia

Aims Plants play an important role in ecosystem processes.Functional meaning of trait variation in wide environmental gradients is well known but is scarcely known across narrow gradients.We analyze the variation of morphological,physical and chemical traits of dom-inant plant species and the potential rates of dry mass loss and N release/immobilization during senesced leaf decomposition of these species across a narrow aridity gradient,and to identify indicative traits useful to set species functional groups sharing decomposition patterns.Methods We analyzed the variation of morphological,physical and chemical traits(specific leaf area,seed mass,N and soluble phenols in green and senesced leaves,plant height)in dominant plant species at 12 sites across an aridity gradient in northern Patagonia,Argentina.We collected senesced leaves of each plant species at each site and used them to estimate the poten-tial rates of dry mass loss and N release/immobilization from decomposing senesced leaves in a microcosm experiment.We analyzed the variation of plant traits and decomposition rates across the aridity gradient.We grouped plants species accord-ing to growth forms(perennial grasses,deciduous shrubs,ever-green shrubs)and different combinations of morpho-physical and chemical traits of green and senesced leaves and compared the potential rates of dry mass loss and N release/immobiliza-tion during leaf decomposition among these groups delimited by each grouping criteria.Important Findings Plant traits did not vary across the aridity gradient.The potential rate of dry mass loss was positively related to aridity,while the potential rate of N release/immobilization did not vary across the gradient.Grouping species by separately morpho-physical and chemical traits resulted in a large overlapping in mean values of decomposition rates among groups.In contrast,plant groupings based on growth forms and those including all morpho-physical and chemical traits of green or senesced leaves yielded groups with differentiated rates of decomposition processes.The two latter groupings clustered spe-cies from more than one growth form indicating some overlapping in the rates of decomposition processes among species of different growth forms.Among traits,N concentration in senesced leaves and plant height explained the highest variation in decomposition rates being positively related to potential rates of dry mass loss and N release/immobilization.We concluded that plant groupings based on morpho-physical and chemical traits of either green or senesced leaves may be more powerful to differentiate functional species groups sharing decomposition patterns than the growth form group-ing.Moreover,plant height and N concentration in senesced leaves may be considered relevant synthetic functional traits in relation to decomposition processes in narrow aridity gradients.