Flooding Depth and Flooding Duration with the Zonation of Riparian Plant Communities in the Three Gorges Reservoir of China

Abstract

The hydraulics of flows, especially the flooding process, influence the patterns of riparian plant zonation. Different characteristics of the flooding process should be analyzed to correlate plant zonation with flooding due to their different effect modes. The effects of flooding characteristics on riparian plants have yet to be studied, especially in the field. Thus, two elements of the flow regime, flooding duration and depth, were analyzed in relation to the riparian plants of the Three Gorges Reservoir. The taxonomic indices and the functional diversity of the riparian plants in three seasons in 2019 and the corresponding inundation character were surveyed. Our results showed that the riparian plant diversity and functional diversity varied by season. A significant negative relationship between plant diversity and flooding depth was observed, while flooding duration was not a significant predictor in different seasons. The greater explanatory capacity of flooding depth than that of flooding duration suggests that flooding depth could be a better indicator of the zonation of the riparian vegetation in this area. Concerning the vital component of flow hydraulics, growing opportunities to study flooding depth and strategies that consider both flooding time and flooding depth in a reservoir should be offered, as they will assist in refining process-based river restoration.