Speaker
Description
Dry grasslands are vulnerable to climate and land use change. Increasing temperatures, drought, grazing cessation or nitrogen deposition result in shifts in taxonomic and functional composition. We resurveyed vegetation plots of dry grasslands after three decades and tested the hypotheses that species richness and diversity decreased both at the scale of the species pool and single communities, functional composition shifted towards more competitive and short-lived trait values and that these responses differed between the different grassland communities, depending on their functional characteristics and the environmental stress level.
The size of the regional species pool did not decrease over the last 30 years. The functional turnover of the species pool points to changing precipitation patterns and an increasing frequency of drought events over the study period as main drivers of change. A lower number of species flowering in midsummer and a higher number of early-flowering species in the resurvey suggests the avoidance of summer droughts and taking advantage of more warm and moist spring conditions. At the community scale, species richness and alpha diversity increased over time, in spite of a decreasing plant cover. This increase was mainly caused by annual plant species, indicating drought avoidance as the preferential survival strategy. The studied community types varied in the magnitude of changes in species richness and diversity as well as their species and functional responses, with shifts being independent from the severity of environmental stress.
Dry grassland communities have undergone significant shifts in both species and functional composition, in favour of generalist species with faster life-cycles and at the disadvantage of specialist species.
| Status Group | Doctoral Researcher |
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