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

Abstract

The historic land-use changes in grassland habitats may have lead to community level selection on seed mass as a response to the environmental changes. A time-series analysis of Danish grassland pin-point plant cover data from an eight-year period was carried out to investigate such a selection response. Across four grassland habitat types, community selection towards lighter seeds was observed during the eight-year period, but generally only limited trait selection was observed on seed mass. The mostly negative result may partly be due to the relatively conservative analysis, where the continuous plant trait variables are used for grouping plant species into functional types, which are then treated as dependent variables. This method was chosen in order to account for the sampling process of the vegetation 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. In conclusion, only limited seed mass selection was observed in semi-natural grasslands that was not subjected to successional processes.

Selection against ruderals in Danish grasslands over an eight-year period

“…These previous observations of grassland vegetation change are further corroborated by this study, since the relative proportion of plant species with a Grime C strategy was found to increase relative to plant species with a Grime R strategy. Moreover, and possibly also a selection response to these environmental changes, a significant community selection towards lighter seeds (Damgaard, 2021b) and against insect pollinated plants ( Ehlers et al, 2021) has been observed in Danish grasslands.…”