Deciduous oaks(Quercus spp.)are distributed from subalpine to tropical regions in the northern hemi-sphere and have important roles as carbon sinks and in climate change mitigation.Determining variations in plant func...Deciduous oaks(Quercus spp.)are distributed from subalpine to tropical regions in the northern hemi-sphere and have important roles as carbon sinks and in climate change mitigation.Determining variations in plant functional traits at multiple biological levels and linking them to environmental variables across geographical ranges is important for forecasting range-shifts of broadly-distrib-uted species under climate change.We sampled leaves of five deciduous Quercus spp.covering approximately 20°of latitude(~21°N-41°N)and 20 longitude(~99°E-119°E)across China and measured 12 plant functional traits at different biological levels.The traits varied distinctively,either within each biological level or among different levels driven by climatic and edaphic variables.Traits at the organ level were significantly correlated with those at the cellular and tissue levels,while traits at the whole-plant level only correlated with those at the tissue level.The Quercus species responded to changing environments by regulating stomatal size,leaf thickness and the palisade mesophyll thickness to leaf thickness ratios with contrasting degree of effect to adjust the whole-plant functioning,i.e.,intrinsic water use efficiency(iWUE),carbon supply and nitrogen availability.The results suggest that these deciduous Quercus spp.will maintain vigour by increasing iWUE when subjected to large temperature changes and insufficient moisture,and by accu-mulating leaf non-structural carbohydrates under drought conditions.The findings provide new insights into the inher-ent variation and trait coordination of widely distributed tree species in the context of climate change.展开更多
Aims Studies integrating phylogenetic history and large-scale community assembly are few,and many questions remain unanswered.Here,we use a global coastal dune plant data set to uncover the important factors in commun...Aims Studies integrating phylogenetic history and large-scale community assembly are few,and many questions remain unanswered.Here,we use a global coastal dune plant data set to uncover the important factors in community assembly across scales from the local filtering processes to the global long-term diversification and dispersal dynamics.Coastal dune plant communities occur worldwide under a wide range of climatic and geologic conditions as well as in all biogeographic regions.However,global patterns in the phylogenetic composition of coastal dune plant communities have not previously been studied.Methods The data set comprised vegetation data from 18463 plots in New Zealand,South Africa,South America,North America and Europe.The phylogenetic tree comprised 2241 plant species from 149 families.We calculated phylogenetic clustering(Net Relatedness Index,NRI,and Nearest Taxon Index,NTI)of regional dune floras to estimate the amount of in situ diversification relative to the global dune species pool and evaluated the relative importance of land and climate barriers for these diversification patterns by geographic analyses of phylogenetic similarity.We then tested whether dune plant communities exhibit similar patterns of phylogenetic structure within regions.Finally,we calculated NRI for local communities relative to the regional species pool and tested for an association with functional traits(plant height and seed mass)thought to vary along sea–inland gradients.Important Findings Regional species pools were phylogenetically clustered relative to the global pool,indicating regional diversification.NTI showed stronger clustering than NRI pointing to the importance of especially recent diversifications within regions.The species pools grouped phylogenetically into two clusters on either side of the tropics suggesting greater dispersal rates within hemispheres than between hemispheres.Local NRI plot values confirmed that most communities were also phylogenetically clustered within regions.NRI values decreased with increasing plant height and seed mass,indicating greater phylogenetic clustering in communities with short maximum height and good dispersers prone to wind and tidal disturbance as well as salt spray,consistent with environmental filtering along sea–inland gradients.Height and seed mass both showed significant phylogenetic signal,and NRI tended to correlate negatively with both at the plot level.Low NRI plots tended to represent coastal scrub and forest,whereas high NRI plots tended to represent herb-dominated vegetation.We conclude that regional diversification processes play a role in dune plant community assembly,with convergence in local phylogenetic community structure and local variation in community structure probably reflecting consistent coastal-inland gradients.Our study contributes to a better understanding of the globally distributed dynamic coastal ecosystems and the structuring factors working on dune plant communities across spatial scales and regions.展开更多
Aims Mechanisms of plant drought resistance include both tolerance and avoidance.Xylem vulnerability to embolism and turgor loss point are considered traits that confer tolerance,while leaf abscission and deciduousnes...Aims Mechanisms of plant drought resistance include both tolerance and avoidance.Xylem vulnerability to embolism and turgor loss point are considered traits that confer tolerance,while leaf abscission and deciduousness characterizes the avoidance strategy.While these mechanisms are thought to trade-off expressing a continuum among species,little is known on how variation in the timing and duration of leaf shedding in response to drought affect the relationship between xylem and leaf tolerance.In the present study,we explored the extent to which drought tolerance differs between two oak(Quercus)species that exhibit different leaf shedding behaviours.Particularly,we predicted that Q.deserticola Trel.,which loses leaves at the end of the dry season(late-deciduous)and is thus exposed to a greater risk of cavitation,would be more drought tolerant and more conservative in its water use than Q.laeta Liebm.,which loses its leaves for only a short period of time in the middle of the dry season(brevideciduous).Methods The study was conducted in central Mexico in a single population of each of the two oak species,separated from each other by a distance of 1.58 km,and by an altitudinal difference of 191 m.Quercus deserticola(late deciduous)is more frequent down slope,while Q.laeta(brevideciduous)tends to occur at higher elevations along the gradient.We assessed seasonal differences(rainy versus dry season)in native stem hydraulic conductivity,and tested for variation in xylem vulnerability to cavitation,leaf water use and leaf turgor loss point between the two species.Important Findings The two oak species did not differ in traits conferring drought tolerance,including xylem vulnerability to embolism,leaf turgor loss point,or stomatal conductance.However,both species had different performance during the dry season;the brevideciduous species had lower negative impact in the xylem function than the late-deciduous species.Overall,seasonal changes in plant physiological performance between the two oak species were determined by a reduction in the canopy leaf area.展开更多
基金supported by the Key Area Research and Development Program of Guangdong Province(2022B1111230001)theScience and Technology Foundation of Guangxi Zhuang Autonomous Region(Guike AD23026080)+1 种基金the National Natural Science Founda tion of China(No.42071065)Natural Science Foundation of US(No.2021898).
文摘Deciduous oaks(Quercus spp.)are distributed from subalpine to tropical regions in the northern hemi-sphere and have important roles as carbon sinks and in climate change mitigation.Determining variations in plant functional traits at multiple biological levels and linking them to environmental variables across geographical ranges is important for forecasting range-shifts of broadly-distrib-uted species under climate change.We sampled leaves of five deciduous Quercus spp.covering approximately 20°of latitude(~21°N-41°N)and 20 longitude(~99°E-119°E)across China and measured 12 plant functional traits at different biological levels.The traits varied distinctively,either within each biological level or among different levels driven by climatic and edaphic variables.Traits at the organ level were significantly correlated with those at the cellular and tissue levels,while traits at the whole-plant level only correlated with those at the tissue level.The Quercus species responded to changing environments by regulating stomatal size,leaf thickness and the palisade mesophyll thickness to leaf thickness ratios with contrasting degree of effect to adjust the whole-plant functioning,i.e.,intrinsic water use efficiency(iWUE),carbon supply and nitrogen availability.The results suggest that these deciduous Quercus spp.will maintain vigour by increasing iWUE when subjected to large temperature changes and insufficient moisture,and by accu-mulating leaf non-structural carbohydrates under drought conditions.The findings provide new insights into the inher-ent variation and trait coordination of widely distributed tree species in the context of climate change.
基金A.K.B.was supported by the Faculty of Science and Technology,Aarhus University(2008-218/5-24)Augustinus’Foundation(11-0677)+4 种基金Oticon(11-0565)Niels Bohr Foundation and Aarhus Universitets Forsknings Fond(AUFFF2011-FLS330)J.-C.S.was supported by the European Research Council(ERC-2012-StG-310886-HISTFUNC)Additionally,we also consider this article a contribution of Center for Informatics Research on Complexity in Ecology(CIRCE)funded by Aarhus University and Aarhus University Research Foundation under the AU IDEAS program.
文摘Aims Studies integrating phylogenetic history and large-scale community assembly are few,and many questions remain unanswered.Here,we use a global coastal dune plant data set to uncover the important factors in community assembly across scales from the local filtering processes to the global long-term diversification and dispersal dynamics.Coastal dune plant communities occur worldwide under a wide range of climatic and geologic conditions as well as in all biogeographic regions.However,global patterns in the phylogenetic composition of coastal dune plant communities have not previously been studied.Methods The data set comprised vegetation data from 18463 plots in New Zealand,South Africa,South America,North America and Europe.The phylogenetic tree comprised 2241 plant species from 149 families.We calculated phylogenetic clustering(Net Relatedness Index,NRI,and Nearest Taxon Index,NTI)of regional dune floras to estimate the amount of in situ diversification relative to the global dune species pool and evaluated the relative importance of land and climate barriers for these diversification patterns by geographic analyses of phylogenetic similarity.We then tested whether dune plant communities exhibit similar patterns of phylogenetic structure within regions.Finally,we calculated NRI for local communities relative to the regional species pool and tested for an association with functional traits(plant height and seed mass)thought to vary along sea–inland gradients.Important Findings Regional species pools were phylogenetically clustered relative to the global pool,indicating regional diversification.NTI showed stronger clustering than NRI pointing to the importance of especially recent diversifications within regions.The species pools grouped phylogenetically into two clusters on either side of the tropics suggesting greater dispersal rates within hemispheres than between hemispheres.Local NRI plot values confirmed that most communities were also phylogenetically clustered within regions.NRI values decreased with increasing plant height and seed mass,indicating greater phylogenetic clustering in communities with short maximum height and good dispersers prone to wind and tidal disturbance as well as salt spray,consistent with environmental filtering along sea–inland gradients.Height and seed mass both showed significant phylogenetic signal,and NRI tended to correlate negatively with both at the plot level.Low NRI plots tended to represent coastal scrub and forest,whereas high NRI plots tended to represent herb-dominated vegetation.We conclude that regional diversification processes play a role in dune plant community assembly,with convergence in local phylogenetic community structure and local variation in community structure probably reflecting consistent coastal-inland gradients.Our study contributes to a better understanding of the globally distributed dynamic coastal ecosystems and the structuring factors working on dune plant communities across spatial scales and regions.
基金supported by Dirección General de Asuntos de Personal Académico(DGAPA)from Universidad Nacional Autónoma de México(UNAM)[Grant no.IA203418 and IA204916 to F.P.G.,and IN207417 to A.G.R.].
文摘Aims Mechanisms of plant drought resistance include both tolerance and avoidance.Xylem vulnerability to embolism and turgor loss point are considered traits that confer tolerance,while leaf abscission and deciduousness characterizes the avoidance strategy.While these mechanisms are thought to trade-off expressing a continuum among species,little is known on how variation in the timing and duration of leaf shedding in response to drought affect the relationship between xylem and leaf tolerance.In the present study,we explored the extent to which drought tolerance differs between two oak(Quercus)species that exhibit different leaf shedding behaviours.Particularly,we predicted that Q.deserticola Trel.,which loses leaves at the end of the dry season(late-deciduous)and is thus exposed to a greater risk of cavitation,would be more drought tolerant and more conservative in its water use than Q.laeta Liebm.,which loses its leaves for only a short period of time in the middle of the dry season(brevideciduous).Methods The study was conducted in central Mexico in a single population of each of the two oak species,separated from each other by a distance of 1.58 km,and by an altitudinal difference of 191 m.Quercus deserticola(late deciduous)is more frequent down slope,while Q.laeta(brevideciduous)tends to occur at higher elevations along the gradient.We assessed seasonal differences(rainy versus dry season)in native stem hydraulic conductivity,and tested for variation in xylem vulnerability to cavitation,leaf water use and leaf turgor loss point between the two species.Important Findings The two oak species did not differ in traits conferring drought tolerance,including xylem vulnerability to embolism,leaf turgor loss point,or stomatal conductance.However,both species had different performance during the dry season;the brevideciduous species had lower negative impact in the xylem function than the late-deciduous species.Overall,seasonal changes in plant physiological performance between the two oak species were determined by a reduction in the canopy leaf area.
