Floristic change in the province of Scania in southernmost Sweden 1800-2020: using fragmented data to study landscape-level shifts

Abstract: Vascular plant observances were compiled for 10 well-documented parishes throughout southernmost Sweden from published floras, herbarium specimens, modern inventories, and a large citizen-science database to provide presence/absence of species from 1800-2020 at the decade level. A regionally-specific database of species-specific plant traits and ecological indicator values was used to examine floristic and ecological changes across an extended timeline which indicates that several of the most apparent conservation issues including climate warming, woody encroachment, and soil chemistry alterations have acted for long over a century. The flora has shifted in favor of species with an affinity to higher N and P levels, a warmer climate, and which are generally more competitive. Additionally, species with lower requirements for grazing/mowing, sunlight, and moisture have also increased. In general, the landscape has become more homogenous over time. While these findings show that the impacts of human activity on wild plant species have not suddenly materialized, the acceleration of these changes over the past 50 years is evident. Investigations into the utility and limitation of fragmented data that spans centuries reveal biodiversity loss in a more holistic way by incorporating species already locally extinct more than 100 years ago. When combined with trait-based analyses, it is clear that quantifiable and long-ranging anthropogenic effects have shifted which species dominate the landscape in Scania across time and space.