Disparities in tree mortality among plant functional types(PFTs)in a temperate forest:Insights into size-dependent and PFT-specific patterns

Tree mortality significantly influences forest structure and function,yet our understanding of its dynamic patterns among a range of tree sizes and among different plant functional types(PFTs)remains incomplete.This study analysed size-dependent tree mortality in a temperate forest,encompassing 46 tree species and 32,565 individuals across different PFTs(i.e.,evergreen conifer vs.deciduous broadleaf species,shade-tolerant vs.shade-intolerant species).By employing all-subset regression procedures and logistic generalized linear mixed-effects models,we identified distinct mortality patterns influenced by biotic and abiotic factors.Our results showed a stable mortality patte rn in eve rgreen conifer species,contrasted by a declining pattern in deciduous broadleaf and shadetolerant,as well as shade-intolerant species,across size classes.The contribution to tree mortality of evergreen conifer species shifted from abiotic to biotic factors with increasing size,while the mortality of deciduous broadleaf species was mainly influenced by biotic factors,such as initial diameter at breast height(DBH)and conspecific negative density.For shade-tolerant species,the mortality of small individuals was mainly determined by initial DBH and conspecific negative density dependence,whereas the mortality of large individuals was subjected to the combined effect of biotic(competition from neighbours)and abiotic factors(i.e.,convexity and pH).As for shade-intolerant species,competition from neighbours was found to be the main driver of tree mortality throughout their growth stages.Thus,these insights enhance our understanding of forest dynamics by revealing the size-dependent and PFT-specific tree mortality patterns,which may inform strategies for maintaining forest diversity and resilience in temperate forest ecosystems.

Classification of plant functional types based on the nutrition traits： a case study on alpine meadow community in the Zoigê Plateau

The ecological concept of Plant Functional Types（PFTs）, which refers to the assemblage of plants with certain functional traits, has been introduced for the study of plant responses to the environment change and human disturbance. Taking the alpine meadow community in the Zoigê Plateau as a study case, this paper classified PFTs in terms of plant nutrition traits. The sequential results are as follows.（1） The main herbages in the Zoigê Plateau included 16 species in 5 families. Among the five families, Cyperaceae vegetation accounted for 81.37%of herbage area in total, while the remaining 4families occupied less than 20%. As for the species,Kobresia setchwanensis Hand.-Maizz. was dominant,accounting for 48.74% of the total area; while the remaining 51.26% was comprised of Polygonum viviparum L., Anaphalis fiavescens Hand.-Mazz.,Stipa aliena Keng and other species.（2） By using the Principal Component Analysis（PCA）, the assessment of herbages nutrition was carried out based on the comprehensive multi-index evaluation model.Polygonum viviparum L. had the highest nutritional value score（1.43）, and Stipa aliena Keng had the lowest（-1.40）. Nutritional value of herbage species had a significantly positive correlation with altitude（P＆lt;0.01） in the Zoigê Plateau.（3） Based on the nutritional values, herbages in the Zoigê Plateau could be grouped into 3 nutrition PFTs（high, medium and low） by using the Natural Breaks（Jenks） method.

Effects of Plant Functional Types,Climate and Soil Nitrogen on Leaf Nitrogen along the North-South Transect of Eastern China

We conducted a systematic census of leaf N for 102 plant species at 112 research sites along the North-South Transect of Eastern China （NSTEC） following the same protocol, to explore how plant functional types （PFTs） and environmental factors affect the spatial pattern of leaf N. The results showed that mean leaf N was 17.7 mg g^-1 for all plant species. The highest and lowest leaf N were found in deciduous-broadleaf and evergreen-conifer species, respectively, and the ranking of leaf N from high to low was： deciduous 〉 evergreen species, broadleaf 〉 coniferous species, shrubs ≈ trees 〉 grasses. For all data pooled, leaf N showed a convex quadratic response to mean annual temperature （MAT）, and a negative linear relationship with mean annual precipitation （MAP）, but a positive linear relationship with soil nitrogen concentration （Nsoil）. These patterns were similar when PFTs were examined individually. Importantly, PFTs, climate and Nsoil, jointly explained 46.1% of the spatial variation in leaf N, of which the independent explanatory powers of PFTs, climate and Nsoil, were 15.6%, 2.3% and 4.7%, respectively. Our findings suggest that leaf N is regulated by climate and Nsoil, mainly via plant species composition. The wide scale empirical relationships developed here are useful for understanding and modeling of the effects of PFTs and environmental factors on leaf N.

Trait-based representation of hydrological functional properties of plants in weather and ecosystem models

Land surface models and dynamic global vegetation models typically represent vegetation through coarse plant functional type groupings based on leaf form, phenology, and bioclimatic limits. Although these groupings were both feasible and functional for early model generations, in light of the pace at which our knowledge of functional ecology, ecosystem demographics, and vegetation-climate feedbacks has advanced and the ever growing demand for enhanced model performance, these groupings have become antiquated and are identified as a key source of model uncertainty. The newest wave of model development is centered on shifting the vegetation paradigm away from plant functional types(PFTs)and towards flexible trait-based representations. These models seek to improve errors in ecosystem fluxes that result from information loss due to over-aggregation of dissimilar species into the same functional class. We advocate the importance of the inclusion of plant hydraulic trait representation within the new paradigm through a framework of the whole-plant hydraulic strategy. Plant hydraulic strategy is known to play a critical role in the regulation of stomatal conductance and thus transpiration and latent heat flux. It is typical that coexisting plants employ opposing hydraulic strategies, and therefore have disparate patterns of water acquisition and use. Hydraulic traits are deterministic of drought resilience, response to disturbance, and other demographic processes. The addition of plant hydraulic properties in models may not only improve the simulation of carbon and water fluxes but also vegetation population distributions.

The unimodal latitudinal pattern of K,Ca and Mg concentration and its potential drivers in forest foliage in eastern China

Potassium(K),calcium(Ca),and magnesium(Mg)are essential elements with important physiological functions in plants.Previous studies showed that leaf K,Ca,and Mg concentrations generally increase with increasing latitudes.However,recent meta-analyses suggested the possibility of a unimodal pattern in the concentrations of these elements along latitudinal gradients.The authenticity of this unimodal latitudinal pattern,however,requires validation through large-scale field experimental data,and exploration of the underlying mechanisms if the pattern is confirmed.Here,we collected leaves of common species of woody plants from 19 montane forests in the north-south transect of eastern China,including 322 species from 160 genera,67 families;and then determined leaf K,Ca,and Mg concentrations to explore their latitudinal patterns and driving mechanisms.Our results support unimodal latitudinal patterns for all three elements in woody plants across eastern China,with peak values at latitude 36.5±1.0°N.The shift of plant-functional-type compositions from evergreen broadleaves to deciduous broadleaves and to conifers along this latitudinal span was the key factor contributing to these patterns.Climatic factors,mainly temperature,and to a lesser extent solar radiation and precipitation,were the main environmental drivers.These factors,by altering the composition of plant communities and regulating plant physiological activities,influence the latitudinal patterns of plant nutrient concentrations.Our findings also suggest that high leaf K,Ca,and Mg concentrations may represent an adaptive strategy for plants to withstand water stress,which might be used to predict plant nutrient responses to climate changes at large scales,and broaden the understanding of biogeochemical cycling of K,Ca,and Mg.

Predicting plant traits and functional types response to grazing in an alpine shrub meadow on the Qinghai-Tibet Plateau

The identification of easily measured plant functional types (PFTs) that consistently predict grazing response would be a major advance.The responses to grazing of individual traits and PFTs were analyzed along a grazing gradient in an alpine shrub meadow on the Qinghai-Tibet Plateau,China.Three response types were identified;grazing increaser (GI),grazing decreaser (GD),and neutral (NE) for both traits and PFTs.Seven traits were measured:plant height,economic group,cotyledon type,plant inclination,growth form,life cycle,and vegetative structure.The first five were significantly affected by grazing.Ordinal regressions for grazing response of the seven traits showed that the best single predictors of response were growth form (including the attributes "Scattered","Bunched" or "Closely Bunched"),and plant inclination ("Rosette","Prostrate",or "Erect"),followed by economic group ("Shrub","Grass","Sedge","Legume","Forb",or "Harmful") and plant height ("Tall","Medium",or "Small").Within the four optimal traits,the summed dominance ratio (SDR) of small plants,forbs,rosette and bunched plants,invariably increased,while that of tall plants,shrubs,grasses,and erect plants decreased,when grazing pressure was enhanced.Canonical correspondence analysis (CCA) identified eleven explanatory PFTs based on 195 defined PFTs,by combining the different attributes of the four optimal traits.Among explanatory PFTs,the most valuable in predicting the community response to grazing were Tall×Shrub×Erect×Scattered and Small×Forb×Rosette,as these have the closest connections with grazing disturbance and include fewer species.Species richness,diversity,and community evenness,did not differ among grazing treatments because turnover occurred in component species and their relative abundances along the grazing gradient.We have demonstrated that a minimum set of PFTs resulting from optimal individual traits can provide consistent prediction of community responses to grazing in this region.This approach provides a more accurate indicator of change within a changing environment than do univariate measures of species diversity.We hope to provide a link between management practices and vegetation structure,forming a basis for future,large scale,plant trait comparisons.

Projections of land use changes under the plant functional type classification in different SSP-RCP scenarios in China

Land use projections are crucial for climate models to forecast the impacts of land use changes on the Earth’s system.However,the spatial resolution of existing global land use projections(e.g.,0.25°×0.25°in the Land-Use Harmonization(LUH2)datasets)is still too coarse to drive regional climate models and assess mitigation effectiveness at regional and local scales.To generate a high-resolution land use product with the newest integrated scenarios of the shared socioeconomic pathways and the representative concentration pathways(SSPs-RCPs)for various regional climate studies in China,here we first conduct land use simulations with a newly developed Future Land Uses Simulation(FLUS)model based on the trajectories of land use demands extracted from the LUH2 datasets.On this basis,a new set of land use projections under the plant functional type(PFT)classification,with a temporal resolution of 5 years and a spatial resolution of 5 km,in eight SSP-RCP scenarios from 2015 to 2100 in China is produced.The results show that differences in land use dynamics under different SSP-RCP scenarios are jointly affected by global assumptions and national policies.Furthermore,with improved spatial resolution,the data produced in this study can sufficiently describe the details of land use distribution and better capture the spatial heterogeneity of different land use types at the regional scale.We highlight that these new land use projections at the PFT level have a strong potential for reducing uncertainty in the simulation of regional climate models with finer spatial resolutions.

Temporal shifts in the explanatory power and relative importance of litter traits in regulating litter decomposition

Background:Litter traits critically affect litter decomposition from local to global scales.However,our understanding of the temporal dynamics of litter trait-decomposition linkages,especially their dependence on plant functional type remains limited.Methods:We decomposed the leaf litter of 203 tree species that belong to two different functional types(deciduous and evergreen)for 2 years in a subtropical forest in China.The Weibull residence model was used to describe the different stages of litter decomposition by calculating the time to 10%,25%and 50%mass loss(Weibull t_(1/10),t_(1/4),and t_(1/2)respectively)and litter mean residence time(Weibull MRT).The resulting model parameters were used to explore the control of litter traits(e.g.,N,P,condensed tannins and tensile strength)over leaf litter decomposition across different decomposition stages.Results:The litter traits we measured had lower explanatory power for the early stages(Weibull t_(1/10)and t_(1/4))than for the later stages(Weibull t_(1/2)and MRT)of decomposition.The relative importance of different types of litter traits in influencing decomposition changed dramatically during decomposition,with physical traits exerting predominant control for the stages of Weibull t_(1/10)and MRT and nutrient-related traits for the stages of Weibull t_(1/4),and t_(1/2).Moreover,we found that litter decomposition of the early three stages(Weibull t_(1/10),t_(1/4),and t_(1/2))of the two functional types was controlled by different types of litter traits;that is,the litter decomposition rates of deciduous species were predominately controlled by nutrient-related traits,while the litter decomposition rates of evergreen species were mainly controlled by carbon-related traits.Conclusions:This study suggests that litter trait-decomposition linkages vary with decomposition stages and are strongly mediated by plant functional type,highlighting the necessity to consider their temporal dynamics and plant functional types for improving predictions of litter decomposition.

Using machine learning algorithms to estimate stand volume growth of Larix and Quercus forests based on national-scale Forest Inventory data in China

Estimating the volume growth of forest ecosystems accurately is important for understanding carbon sequestration and achieving carbon neutrality goals.However,the key environmental factors affecting volume growth differ across various scales and plant functional types.This study was,therefore,conducted to estimate the volume growth of Larix and Quercus forests based on national-scale forestry inventory data in China and its influencing factors using random forest algorithms.The results showed that the model performances of volume growth in natural forests(R^(2)=0.65 for Larix and 0.66 for Quercus,respectively)were better than those in planted forests(R^(2)=0.44 for Larix and 0.40 for Quercus,respectively).In both natural and planted forests,the stand age showed a strong relative importance for volume growth(8.6%–66.2%),while the edaphic and climatic variables had a limited relative importance(<6.0%).The relationship between stand age and volume growth was unimodal in natural forests and linear increase in planted Quercus forests.And the specific locations(i.e.,altitude and aspect)of sampling plots exhibited high relative importance for volume growth in planted forests(4.1%–18.2%).Altitude positively affected volume growth in planted Larix forests but controlled volume growth negatively in planted Quercus forests.Similarly,the effects of other environmental factors on volume growth also differed in both stand origins(planted versus natural)and plant functional types(Larix versus Quercus).These results highlighted that the stand age was the most important predictor for volume growth and there were diverse effects of environmental factors on volume growth among stand origins and plant functional types.Our findings will provide a good framework for site-specific recommendations regarding the management practices necessary to maintain the volume growth in China's forest ecosystems.

Evaluating the Tree Population Density and Its Impacts in CLM-DGVM

Vegetation population dynamics play an essential role in shaping the structure and function of terrestrial ecosystems. However, large uncertainties remain in the parameterizations of population dynamics in current Dynamic Global Vegetation Models （DGVMs）. In this study, the global distribution and probability density functions of tree population densities in the revised Community Land Model-Dynamic Global Vegetation Model （CLM-DGVM） were evaluated, and the impacts of population densities on ecosystem characteristics were investigated. The results showed that the model predicted unrealistically high population density with small individual size of tree PFTs （Plant Punetional Types） in boreal forests, as well as peripheral areas of tropical and temperate forests. Such biases then led to the underestimation of forest carbon storage and incorrect carbon allocation among plant leaves, stems and root pools, and hence predicted shorter time scales for the building/recovering of mature forests. These results imply that further improvements in the parameterizations of population dynamics in the model are needed in order for the model to correctly represent the response of ecosystems to climate change.

Progress of vegetation modelling and future research prospects

Terrestrial vegetation is a crucial component of the Earth system,and its changes not only represent one of the most distinct aspects of climate change but also exert significant feedback within the climate system by exchanging energy,moisture,and carbon dioxide.To quantitatively and mechanistically study climate-vegetation feedback,numerical vegetation models have been developed on the theory of ecophysiological constraints on plant functional types.The models eventually can simulate vegetation distribution and succession across different spatial and temporal scales,and associated terrestrial carbon cycle processes by categorizing vegetation into biomes according different plant functional types and their associated environmental factors.Here we review the developing history of vegetation models and provide recent advances and future directions.Before 21st century,static vegetation models,as developed statistical models,can only simulate equilibrated characteristics of vegetation distribution.In last several decades,Dynamic Global Vegetation Models(DGVMs)have been developed to simulate instantaneous responses of vegetation to climate change and associated dynamics,and can be coupled with Earth system models to investigate interactions among atmosphere,ocean,and land.DGVMs are also widely applied to investigate the dynamics accounting for changes in the geographic distribution patterns of land surface vegetation at different spatial and temporal scales and to assess the impacts of terrestrial carbon and water fluxes and land use changes.We suggest that future vegetation modeling could integrate with machine learning,and explore vegetation transient response and feedback as well as impacts of process hierarchies and human activities on climate and ecosystem.

Plant phenols contents and their changes with nitrogen availability in peatlands of northeastern China

Aims Climate warming and increasing nitrogen(N)deposition have influenced plant nutrient status and thus plant carbon(C)fixation and vegetation composition in boreal peatlands.Phenols,which are secondary metabolites in plants for defense and adaptation,also play important roles in regulating peatland C dynamics due to their anti-decomposition properties.However,how the phenolic levels of different functional types of plants vary depending on nutrient availability remain unclear in boreal peatlands.Methods Here,we investigated total phenols contents(TPC)and total tannins contents in leaves of 11 plant species in 18 peatlands of the Great Hing’an Mountains area in northeastern China,and examined their variations with leaf N and phosphorus(P)and underlying mechanisms.Important Findings Shrubs had higher TPC than graminoids,indicating less C allocation to defense and less uptake of organic N in faster-growing and nonmycorrhizal graminoids than in slower-growing and mycorrhizal shrubs.For shrubs,leaf TPC decreased with increasing N contents but was not influenced by changing leaf phosphorus(P)contents,which suggested that shrubs would reduce the C investment for defense with increasing N availability.Differently,leaf TPC of graminoids increased with leaf N contents and decreased with leaf P contents.As graminoids are more N-limited and less P-limited,we inferred that graminoids would increase the defensive C investment under increased nutrient availability.We concluded that shrubs would invest more C in growth than in defense with increasing N availability,but it was just opposite for graminoids,which might be an important mechanism to explain the resource competition and encroachment of shrubs in boreal peatlands in the context of climate warming and ever-increasing N deposition.

Mediterranean sea cliff plants:morphological and physiological responses to environmental conditions

Aims The plants of Mediterranean sea cliff ecosystems are resistant to several environmental challenges.In this study,six species typical of the coastal rocky cliffs have been analyzed in order to evaluate their diverse morphological and physiological responses to their environment across the seasons,and to examine the strategy of the ecological group to which each species belongs.Since these species are widespread across the Mediterranean region,our aim was also to highlight their ecophysiological features in habitats where the direct influence of the sea is stronger.Methods The selected species are characteristic of the sea cliffs of Elba island(Tyrrhenian sea,Italy):the halophyte Crithmum maritimum,the semideciduous Helichrysum italicum and Lavandula stoechas and the sclerophylls Myrtus communis,Quercus ilex and Rhamnus alaternus.Four morphological traits-canopy height,leaf area,specific leaf area and leaf dry matter content-and two physiological traits-leaf water potential(LWP)and photosynthetic efficiency(PE),measured before the dawn and at midday-were analyzed.Water potential was measured by a pressure chamber and photosynthetic efficiency was determined by the analysis of chlorophyll fluorescence.Plant performance was also evaluated by calculating chronic(PIchr)and dynamic photoinhibition(PIdyn).Important Findings Crithmum maritimum showed high resistance to the recurrent dry periods,because of the high water storage capacity of its leaves and its PE declined markedly only in July,under the harshest climatic conditions.Semideciduous taxa utilize primarily an avoidance strategy,which aims at reducing the overall leaf surface,while sclerophylls mostly show a tolerance strategy towards the prevailing stressors,as demonstrated by LWP and PE,that are lower in the sclerophylls than in the semideciduous taxa during summer,due to osmoregulation and photoinhibition,respectively.Furthermore,variability of physiological parameters was higher in the sclerophylls than in the semideciduous taxa,because the former had to withstand wider oscillations of their LWP and PE.The sclerophyllous taxa underwent a slight loss of PE also in winter,likely owing to the combined action of low temperature and high irradiance.In Mediterranean sea cliff ecosystems,the stressful combination of high irradiance,high temperatures and low rainfall typical of the summer season may have been intensified by the shallow soil which displays a poor water storage capacity.On the other hand,winter stress,caused by high solar radiation and low temperatures,does not seem to seriously affect the performance of the studied species.

Global patterns of the responses of leaf-level photosynthesis and respiration in terrestrial plants to experimental warming

Aims The balance between leaf photosynthesis and respiration of terrestrial plants determines the net carbon(C)gain by vegetation and consequently is important to climate–C cycle feedback.This study is to reveal the global patterns of the responses of leaf-level net photosynthesis and dark respiration to elevated temperature.Methods Data for leaf-level net photosynthesis rate(P_(n))and dark respiration rate(R_(d))in natural terrestrial plant species with standard deviation(or standard error or confidence interval)and sample size were collected from searched literatures on Web of Science.Then a metaanalysis was conducted to estimate the effects of experimental warming on leaf-level P_(n) and R_(d) of terrestrial plants.Important findings Across all the plants included in the analysis,warming enhanced P_(n) and R_(d) significantly by 6.13 and 33.14%,respectively.However,the responses were plant functional type(PFT)specific.Specifically,photosynthesis of C_(4) herbs responded to experimental warming positively but that of C_(3) herbs did not,whereas their respiratory responses were similar,suggesting C_(4) plants would benefit more from warming.The photosynthetic response declined linearly with increasing ambient temperature.The respiratory responses linearly enhanced with the increase in warming magnitude.In addition,a thermal acclimation of R_(d),instead of P_(n),was observed.Although greater proportion of fixed C was consumed(greater R_(d)/P_(n) ratio),warming significantly enhanced the daily net C balance at the leaf level.This provides an important mechanism for the positive responses of plant biomass and net primary productivity to warming.Overall,the findings,including the contrastive responses of different PFTs and the enhancement in daily leaf net C balance,are important for improving model projection of the climate–C cycle feedback.

Nitrogen addition affects plant biomass allocation but not allometric relationships among different organs across the globe

Aims Biomass allocation to different organs is a fundamental plant ecophysiological process to better respond to changing environments;yet,it remains poorly understood how patterns of biomass allocation respond to nitrogen(N)additions across terrestrial ecosystems worldwide.Methods We conducted a meta-analysis using 5474 pairwise observations from 333 articles to assess how N addition affected plant biomass and biomass allocation among different organs.We also tested the'ratio-based optimal partitioning'vs.the'isometric allocation,hypotheses to explain potential N addition effects on biomass allocation.Important Findings We found that(i)N addition significantly increased whole plant biomass and the biomass of different organs,but decreased rootrshoot ratio(RS)and root mass fraction(RMF)while no effects of N addition on leaf mass fraction and stem mass fraction at the global scale;(ii)the effects of N addition on ratio-based biomass allocation were mediated by individual or interactive effects of moderator variables such as experimental conditions,plant functional types,latitudes and rates of N addition and(iii)N addition did not affect allometric relationships among different organs,suggesting that decreases in RS and RMF may result from isometric allocation patterns following increases in whole plant biomass.Despite alteration of ratio-based biomass allocation between root and shoot by N addition,the unaffected allometric scaling relationships among different organs(including root vs.shoot)suggest that plant biomass allocation patterns are more appropriately explained by the isometric allocation hypothesis rather than the optimal partitioning hypothesis.Our findings contribute to better understand N-induced effects on allometric relationships of terrestrial plants,and suggest that these ecophysiological responses should be incorporated into models that aim to predict how terrestrial ecosystems may respond to enhanced N deposition under future global change scenarios.

Bedrock geology interacts with altitude in affecting leaf growth and foliar nutrient status of mountain vascular plants

Aims Altitude is often used as a proxy for ascertaining how warming affects plant growth and leaf level properties.However,we have a poor understanding of how the effects of altitude-related warming varies across geology.therefore,this study examined the independ-ent and interactive effects of altitude and geology and species on plant growth and foliar nutrient status.Methods We determined leaf growth rates and concentrations of major nutrients(nitrogen,N and phosphorus,P)in leaves of five spe-cies across two altitudinal gradients(1200-2200 m)in the Dolomites(south-eastern Alps,Italy).the two transects were located on carbonate bedrock and silicate bedrock,respec-tively.We also determined concentrations of inorganic and organic N and P forms in soils,andδ15N signature in leaves and soils.Important Findings Foliar N concentrations were unrelated to bedrock geology.the negative foliarδ^(15)N signature suggested that organic N was the primary source of N supply across the gradients.Foliar P concentrations were strongly affected by bedrock geology and their altitudinal patterns depended on the concentrations of organic and inorganic P forms in the soil.Phosphates and organic P appeared to be the main sources of P supply.Leaf growth rates increased with higher altitude on silicate bedrock and decreased with higher altitude on carbonate bedrock and presented a significant positive correlation with foliar N:P.In conclusion,bedrock geology inter-acted with altitude in controlling the foliar nutrient status mainly owing to availability of soil P and its effect on foliar nutrient stoichiometry.

Functional attributes of two subtropical shrubs and implications for the distribution and management of endangered bird habitat

Aims The fruits of Erithalis fruticosa l.and Lantana involucrata l.are important in the diet of u federally endangered Kirtland’s Warblers(Setophaga kirtlandii)wintering in the bahamas archi-pelago.These two shrubs occur in tropical and subtropical dry forests,including forests that have been subjected to recent dis-turbance.Despite their importance to the endangered warbler,the disturbance ecology of these shrubs is poorly understood.We sought to determine,based on functional characteristics of the plants,whether their presence is favored by a particular type or regime of disturbance.Methods We used data from field experiments(seed broadcasting and shrub cutting)conducted on the island of Eleuthera,The bahamas to determine mechanisms of and conditions favoring establishment and persistence(‘vital attributes’)of E.fruticosa and L.involucrata,which enabled categorization according to the plant functional types defined by Noble and slatyer(1980).We then compared hypothesized distributions of these plant functional types among different anthropogenic disturbance regimes to observed distribu-tions of E.fruticosa and L.involucrata in order to identify distur-bance regimes most likely to produce habitat used by Kirtland’s Warblers.Important Findings E.fruticosa and L.involucrata were functionally categorized as widely dispersed but largely shade intolerant species capable of establishing or regenerating individuals after disturbance via both seeds and vegetative mechanisms.both hypothesized and observed distribution patterns indicated the shrubs were favored by a regime of frequent disturbance producing open canopy and ground layers.among the anthropogenic disturbances we examined,areas of large-scale land clearing combined with subsequent goat graz-ing most often supported E.fruticosa and L.involucrata,while the shrubs were relatively rare in burned areas.utilizing the plant functional type framework in combination with field data to evaluate predictions of species occurrence among different disturbances regimes provides a strong theoretical basis for conservation strategies.understanding which disturbance types favor a habitat of concern and the mechanisms by which they do so can aid the prior-itization of areas for protection or the design of habitat management protocols.

Thermal acclimation of leaf respiration varies between legume and non-legume herbaceous

Aims Ubiquitous thermal acclimation of leaf respiration could mitigate the respiration increase.However,whether species of different plant functional groups showing distinct or similar acclimation justifies the simple prediction of respiratory carbon(C)loss to a warming climate.Methods In this study,leaf dark respiration(Rd)of illinois bundleflower(IB,legume),stiff goldenrod(GR,C_(3) forbs),indian grass,little bluestem and king ranch bluestem(IG,LB and KB,C_(4) grass)were measured with detached leaves sampled in a 17-year warming experiment.Important Findings The results showed that Rd at 20℃ and 22℃(R_(20) and R_(22))were significantly lower in the warming treatment for all the five species.Lower R_(22) in warmed than R_(20) in control in GR,KB,LB and IG imply acclimation homeostasis,but not in IB.The significant decline in temperature sensitivity of respiration(Q_(10))of GR resulted in the marginal reduction of Q_(10) across species.No significant changes in Q_(10) of C_(4) grasses suggest different acclimation types for C_(3) forbs and C_(4) grass.The magnitude of acclimation positively correlated with leaf C/N.Our results suggest that non-legume species had a rela-tive high acclimation,although the acclimation type was different between C_(3) forbs and C_(4) grasses,and the legume species displayed no acclimation in Rd.Thus,the plant functional types should be taken into account in the grassland ecosystem C models.

Annual mowing mitigates the negative legacy effects of N enrichment on grassland nutrient use efficiency

Aims Plant nutrient use efficiency,an important factor driving primary production,is sensitive to nitrogen(N)deposition.Because of strengthened regulations of N emissions,atmospheric N deposition is decreasing in many countries.It remains unknown whether historical N enrichment would alter plant nutrient use efficiency and whether such impacts would be mitigated by ecosystem management strategy.Methods We assessed the effects of historical N addition and mowing on plant N and phosphorus use efficiency(NUE and PUE)at both functional group and community levels in a temperate steppe after the cessation of 6-year N addition.Important Findings Historical N addition had negative legacy effects on plant NUE but not on PUE at the functional group level.There were negative legacy effects of N addition on community-level NUE and PUE,but only in the unmown plots.Mowing mitigated the negative legacy effects of N enrichment on community-level NUE and PUE by reducing the dominance of tall rhizomatous grass but enhancing that of tall bunchgrass.Our results highlight the importance of community composition variations caused by mowing in driving the legacy effects of N enrichment on community-level nutrient use efficiency.Given the slow recovery of community composition following cessation of N deposition,our findings suggest that the lower nutrient efficiency of plant community would be long-lasting.