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 S?rensen-based multi-site dissimilarity(β sor ) and its underlying true turnover (β sim ) and nestedness (β sne ) 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 relationship 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 and β sne well,but not β sim .Current mean annual temperature determines β sor and β sneof 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 theβ-diversity of entire species assemblages,studies of single plant families can provide complementary insights into the drivers ofβ-diversity of evolutionarily more narrowly de?ned entities.