Propagule pressure and environmental filters related to non-native species success in river-floodplain ecosystems

The flood pulse is the main driving force influencing river floodplain ecosystems. The dominant role of the flood pulse on the success of non-native species (NNSs) is what differentiates floodplains from other ecosystems, in terms of invasion. In this review, I discuss some patterns related to the performance of NNSs in response to the flood pulse. First, floods connect floodplain habitats and spread propagules of NNSs, causing ‘propagule pulses’ in these ecosystems. After the establishment of NNSs, floodplains may function as steppingstones for future invasions, because propagule pulses enhance invasions in nearby landscapes. Second, the flood pulse changes environmental filters, with consequences for invasion success and for the coexistence of native and NNSs. Flooding represents a disturbance that enhances the success of some NNSs by reducing biotic resistance and changing resource availability, but diminishes the success of others. Drought enhances the invasion success mainly of NNSs that colonize the aquatic-terrestrial transition zone. Third, impacts caused by river regulation and global changes alter the flood pulse, which in turn affects invasion success. There is a great degree of idiosyncrasy in these patterns, but they pose a broad perspective that helps to understand and manage NNSs in floodplains.