Down in the flood? How moth communities are shaped in temperate floodplain forests

.  1. We investigated moth communities in relation to flood regime across three riparian regions in lowland eastern Austria. Moths sampled with light traps were segregated into resident and stray species. Resident moths were further partitioned into arboreal and ground‐layer species based on their larval habitat. 2. Regional differences in species diversity and species composition were far stronger than local differences related to flood regime. 3. Stray species (17% of all species and 6% of all individuals sampled) as well as uniques had only negligible influence on diversity and species composition patterns. The single most abundant species turned out to be more problematic for diversity comparisons across regions and habitats than the many rare species and strays. 4. Overall moth diversity and ground‐layer moth diversity were generally not reduced in flooded habitats relative to non‐flooded habitats, and diversity of arboreal moths did not show significant differences between flood regimes. 5. Differences between habitats in their ground‐layer vegetation appear to be more important for floodplain forest moth diversity than variation in woody vegetation with its associated arboreal moth fauna. 6. Patterns in species composition were largely governed by ubiquitous forest species and not by floodplain or wetland habitat specialists. Eighteen of the 44 commonest species were more abundant in flooded habitats, and only 10 of them were more frequent in non‐flooded habitats. 7. Our results revealed no general negative impact of flooding on the diversity and species composition of one rich group of terrestrial herbivorous insects.