Decline in large-seeded species in Danish grasslands over an eight-year period

Abstract

To demonstrate possible community selection on seed size, a time-series analysis of cover data from 236 Danish grassland sites was performed in a linear model. Across four grassland habitat types and during an eight-year period, there was a significant decline in large-seeded species. Therefore, it was not possible to corroborate the initial hypothesis that a historical increase in nitrogen deposition and the observed vegetation changes towards taller and more competitive plant species favored plant species with large seeds. In the analysis, the continuous seed size variable was used to group plant species into functional types. This method was chosen in order to account for the sampling process of the cover data and is in contrast to most other analyses of trait selection, where the community weighted mean of the traits is used as the dependent variable.