Effects Of Hydrological Connectivity On The Substrate And Understory Structure Of Riparian Wetlands In The Middle Ebro River (ne Spain): Implications For Restoration And Management

摘要

The hydroperiod, flooded sediments and riparian understory were examined for eight riparian wetlands of one Ebro River reach (NE Spain) to relate river-floodplain interactions at different spatio-temporal scales with wetland strucuture. This analysis served as a basis for assessing the ecological status of the study reach and proposing a valid restoration plan. A comparison of water-level fluctuations in riparian wetlands with that in the river channel during an ordinary flood was use to characterize the hydro-period. This characterization was further linked with the results of a multivariate analysis performed using sediment physico-chemistry. Moreover, different measures of understory diversity were used to estimate the successional stage of eight riparian wetlands located in the same reach of the Ebro River. We described four hydroperiod types from the examined flood, from disconnected oxbow lakes to backflow channels fluctuating in concert with the Ebro River. Also three types of sediment differ in their organic matter content. Both results were closely related reflecting the dominance of endogenous or alloge-neous processes. However, such heterogeneity was interpreted as being variable over longer spatio-temporal scales. In addition, the riverscape was found to be homogenous and dominated by wetlands at mature successional stages. Consequently, the lack of erosive floods within the reach seems to make inclusion of ecological restoration of geomorpholog-ical dynamics a highly appropriate management objective. Alternative strategies at both reach and site scales are proposed.