Interaction between depth and duration matters: flooding tolerance of 12 floodplain meadow species

Abstract

In riparian landscapes, regular flooding plays a crucial role in the distribution and diversity of plant species. Particularly in floodplain grassland, the microrelief, which is often the result of riverine sedimentation through flooding, leads to differing flooding depths and durations on a microscale, with little-known impacts on plants. Here, we aim to reveal the effects of flooding duration and flooding depth, as well as their interaction, on seedlings of 12 floodplain meadow plant species. To this end, we performed flooding procedures for 2 and 4 weeks with no, partial, and complete submergence using seedlings of floodplain meadow species in six familial pairs with a preference for relatively wetter or drier microhabitats. We show that an increased flooding duration and flooding depth negatively affect the performance of seedlings. The interactive effect of these two factors appears to play an essential role in the flooding tolerance of plant species. In conclusion, our results suggest that the studied factors and their interaction have high importance in determining the flooding tolerance of floodplain meadow plant species. Despite its crucial function, the effect of the depth × duration interaction seems to be underestimated in experimental studies focusing on flooding effects in plants. Thus, this interaction, as well as its combination with other factors, should be studied in more detail to further understand plant responses to flooding events.