Origin of plant trait data matters: Shared species of Northwestern Europe and the Pannonian Ecoregion have different trait values in the two regions

Trait-based ecology considerably increased our comprehension of various fields related to ecology and evolution. As measuring traits can be time-consuming and costly, analyses regularly gather trait data from databases instead of carrying out new measurements. However, intraspecific trait variability can cause considerable differences between the trait values of different population and regions. Here we evaluated whether intraspecific trait variability causes considerable differences in trait values measured in two different regions of Europe. We tested whether regionally measured trait data from the Pannonian Ecoregion differ from trait data of the same species originating from Northwestern Europe, by comparing data from the Pannonian Database of Plant Traits (PADAPT) and the LEDA Traitbase. We evaluated six traits of the same set of species: thousand-seed mass (TSM), seed bank persistence index (SBPI), leaf area (LA), leaf dry matter content (LDMC), specific leaf area (SLA), and leaf dry mass. We found that trait data from the two databases significantly differed for TSM, SBPI, SLA, and LDMC. Our results indicate that the markedly different climate of the two regions can cause substantial intraspecific trait variation, therefore, the geographical origin of trait data matters in trait-based analyses. The findings corroborate the assumption that regionally measured trait data and building regional databases are essential for reliable regional-scale trait-based studies. We conclude that for studies analysing traits in the Pannonian Ecoregion (and possibly in Easter and Central Europe in general), it is advisable to use PADAPT instead of databases compiling data from regions with markedly different climatic conditions.