Abstract
Aim Land use is the foremost cause of global biodiversity decline, but species do not respond equally to land-use practices. Instead, it is suggested that responses vary with species traits, but long-term data on the trait-mediated effects of land-use on communities is scarce. Here we study how forest understory communities have been affected by common land-use practices during 4–5 decades, and whether changes in plant diversity are related to changes in functional composition.
Location Finland
Time period 1968–2019
Major taxa studied Vascular plants
Methods We resurveyed 245 vegetation plots in boreal herb-rich forest understories, and used hierarchical Bayesian linear models to relate changes in diversity, species composition, average plant size, and leaf economic traits to reindeer abundance, forest management intensity, and changes in climate, canopy cover and composition.
Results Forestry decreased species richness and increased turnover, but did not affect functional composition. Increased reindeer densities corresponded with decreased height and specific leaf area, and increased leaf dry matter content, evenness and diversity. Successional changes in the canopy were associated with increased specific leaf area and decreased leaf dry matter content and height over the study period. Effects of reindeer abundance and canopy density on diversity were partially mediated by vegetation height, which had a negative relationship with evenness. Climate change had no discernible effect on any variable.
Main conclusions Functional traits are useful in connecting vegetation changes to the mechanisms that drive them, and provide unique information compared to turnover and diversity metrics. These trait-dependent selection effects could inform whether species benefit or suffer from land use changes and explain observed vegetation shifts under global change.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Models completely rewritten to account for spatial confounders.
