Anthropocene Plant Migration: Regional Shifts in Trait Patterns and Functional Diversity

Over the past centuries, human activities have profoundly reshaped global plant migration patterns, accelerating the movement of species across vast distances. These new arrivals—whether deliberately introduced or transported unintentionally—often possess distinct functional traits that transform local community trait spaces and, in turn, ecosystem processes. Despite these widespread changes, the extent of functional conversions remains poorly understood.

In this study, we combine crowd-sourced plant occurrence data with naturalized species lists to reconstruct global trait distributions for two scenarios: (i) considering all species observed in a region and (ii) excluding neophyte species. By comparing these distributions, we estimate how neophyte introductions have reconfigured ecosystem functional spaces.

Our findings suggest distinct, region-specific shifts in functional traits along the global spectrum of plant form and function. These shifts are particularly evident in principal component 1 (PC1), which is associated with size-related traits such as plant height, rooting depth, and seed mass, and principal component 2 (PC2), which reflects traits like specific leaf area (SLA) and leaf nitrogen per area. For instance, in the Mediterranean, communities appear to have shifted toward larger trait values on PC1, while in Eastern and Central North America, shifts tend toward smaller values. In Western North America, the primary shift occurs along PC2, with increases in SLA and declines in leaf nitrogen per area. In Southern Australia, trait space shifts along both PC1 and PC2, combining smaller size traits with higher SLA values.

These results highlight the significant and varied impacts of Anthropocene plant migration on ecosystem functional properties worldwide, while also identifying gaps and biases in the extensive yet heterogenous crowd-sourced observation data. Moreover, the set of current and past trait patterns may open new opportunities to model the anthropogenic impact on ecosystem processes and properties.