Differential effects of reduced water potential on the germination of floodplain grassland species indicative of wet and dry habitats. Issue 1 (17th February 2014)

• Record Type: Journal Article
• Authors: Ludewig, Kristin; Zelle, Bianka; Eckstein, R. Lutz; Mosner, Eva; Otte, Annette; Donath, Tobias W.
• Is Part Of: Seed science research. Volume 24:Issue 1(2014)
• Page Start: 49
• Page End: 61
• Publication Date: 2014-02-17
• Subjects: alluvial meadows, -- climate change, -- Ellenberg values, -- flood meadows; Seeds -- Periodicals; 631.521
• DOI: 10.1017/S096025851300038X
• Languages: English
• ISSNs: 0960-2585

Abstract

Abstract: Floodplain meadow ecosystems are characterized by high water level fluctuations and highly variable soil water potentials. Additionally, climate change scenarios indicate an increasing risk for summer drought along the northern Upper Rhine and the Middle Elbe River, Germany. While adult plants often persist even after strong changes in water availability, early life phases, such as seed germination and seedling establishment, might be more vulnerable. Therefore we tested whether reduced soil water potentials will affect the germination of meadow species and whether the response varies between (1) forbs indicative of wet and dry habitats and (2) seeds originating from sites along the rivers Elbe and Rhine. We exposed seeds of 20 floodplain meadow species with different moisture requirements from five plant families to a water potential gradient ranging from 0 to − 1.5 MPa. While across species germination percentage and synchrony decreased, germination time increased at reduced water potentials. Germination of the species indicative of dry habitats decreased more strongly, was slower and less synchronous at reduced water potentials than that of species indicative of wet habitats. Seeds from sites along the rivers Elbe and Rhine did not differ in their germination characteristics. We propose that species of wet sites follow an all-or-nothing-strategy with fast and synchronous germination to maximize competitive advantages, betting on a high probability of moist conditions for establishment (optimists). In contrast, species from dry sites appear to follow a bet-hedging strategy with a moisture-sensing mechanism for unsuitable conditions (pessimists), resulting in a slower and less synchronous germination.