Trends in single trait dispersion between early-mid successional stages:the importance of species pool extension and habitat scale

Aims Are there trends of increasing/decreasing dispersion of single,cat-egorical traits related to early/late-successional species between stages of community development?If yes,are these trends depend-ent on species pool extension and habitat scale?Is there a consist-ent reduction in single trait convergence or divergence in any seral stage when scaling down from ecological to local species pool?Methods Presence of all vascular species rooted within plots of 5×5 m was recorded in assemblages of exposed mining spoils(EMS)and heath-lands(HTL),which form a chronosequence on two abandoned ore tailing heaps located close to each other in the south-eastern Carpathians(Romania).Fifteen nominal,trait attributes of plant species co-occurring in the two seral assemblages were collected from available databases and subsequently classified as either suc-cessionally‘pioneer’or‘mature’.The strength of single trait conver-gence or divergence was estimated by comparison with null plant assemblages at patch type(meta-community)level by reference to the ecological or local species pool,and at community level.Important Findings At patch type level,all pioneer and mature trait attributes(apart from short life span),with significant variation between the two seral stages,increased and,respectively,decreased in dispersion irrespective of species pool extension.However,these trends were more conspicuous when using the ecological species pool,very likely due to relaxation in abiotic filtering and dispersal limitation.At community level,no consistent trends were observed between EMS and HTL assemblages,probably because most trait attributes were sorted by microenvironmental filters displaying high variation,like topography or habitat patch geometry.In both seral stages,there was a general weakening of trait convergence or divergence at patch type level when scaling down from the ecological to the local species pool,which was due to niche space contraction.At community level,there was a trend of rise in dispersion of pioneer attributes along the observed chronosequence,presumably imput-able to increasing competition for light and underground water,but an opposite trend of dispersion drop in mature attributes was not so evident.Based on these findings,we proposed two rules of thumb concerning the expected changes in dispersion of trait attributes at patch level along successions and between levels of species pool extension.In conclusion,trends in the successional dynamics of pioneer and mature trait dispersion are clearly detectable at meta-community level,especially by reference to the ecological species pool.Habitat scale and species pool extension are key factors to consider and report when estimating the magnitude of single trait dispersion.

Functional diversity and trait composition of butterfly and bird communities in farmlands of Central Romania

Cultural landscapes all over the world harbor species communities that are taxonomically and functionally diverse.In Eastern Europe,but also in many other regions of the world,the conservation of this farmland biodiversity is threatened by land use intensification and abandonment.In order to counteract the negative effects of land use change in such landscapes,a thorough understanding of the functional relationships between species and their environment is crucial.In this study,we investigated the relationship of functional traits of butterfly and bird communities and environmental conditions in 120 sites in traditional farmlands of southern Transylvania,Romania.First,we compared taxonomic diversity(i.e.,Shannon diversity)with functional diversity(i.e.,functional dispersion),and second,we linked species traits to environmental variables by performing RLQ analyses.Functional traits indicating reproduction,movement,and feeding behavior related with environmental variables describing heterogeneity,amount of woody vegetation,and topography at three different spatial scales.We found positive relationships between taxonomic and functional diversity,as well as strong linkages between species traits and environmental conditions for both groups.Specifically,butterfly composition was most strongly influenced by land use type and life-history strategies.Bird composition was most strongly related to the amount of woody vegetation and nesting and foraging strategies.We conclude that maintaining the typical features of traditional farming landscapes,especially a small-scale heterogeneity in arable land and gradients of woody vegetation cover,would be desirable in order to sustain a high functional diversity in southern Transylvania in the future.

Phenotypic divergences induced by different residence time in invasive common ragweeds

Aims Possible shifts in the phenotypic performance along invasive plants’spreading route are rarely examined due to the discontinuous and incomplete records of exotic species.As the invasion history of common ragweed(Ambrosia artemisiifolia L.)is well documented in Hungary,its residence time is known for each location.By sampling a sequence of older to more recently established populations,we aimed to determine(i)whether there are phenotypic divergences along the historical spreading route of A.artemisiifolia;(ii)which traits are under selection during the invasion process and(iii)the extent of maternal effects on the individual’s performance.Methods We used a hierarchical sampling design to collect seeds from 64 individuals belonging to eight sites in four residence time categories(seven populations along the historical spreading route of ragweed in Hungary and one recently invaded site in Romania).We selected four large and four small individual plants in each population to control for maternal effects.The offspring were reared in a common garden located in Romania.Five vegetative phenotypic traits were measured at the end of the experiments and used in the subsequent analysis(plant height,basal diameter,number of secondary axes,length of the longest secondary axis and biomass).To summarize the variation of these highly correlated traits,principal component analysis was performed first and then the important components were used in linear mixed effect models.Important Findings The residence time categories were significantly distinguished by the first component,which compresses the variation of all five measured traits.The measures gradually decrease from populations with the longest residence time(introduced more than 65 years ago)towards the most recently established populations(established less than 30 years ago).These differences might reflect the invasion history of the populations:the longer the residence time the higher the chance to develop relevant traits beneficial in invasion process.The size of the mother plant significantly influenced not only the seed mass(inversely)but also the adult performance of its offspring(directly).