Contrasting influences of inundation and land use on the rate of floodplain restoration

Abstract

This study examined the assisted natural restoration of native vegetation in an Australian floodplain wetland where flows were reinstated and the river was reconnected to the floodplain, following cessation of agricultural cultivation. Extant vegetation was surveyed three times during an inundation event at plots with different land‐use histories. Restoration rate was more influenced by past land use than long‐term inundation frequency and success decreased with antecedent land‐use intensity. Prolonged land‐use history (>3 years cultivation) restricted restoration success. Sites with longer cultivation histories tended to have fewer aquatic species, more terrestrial species and exotic species. For example, amphibious responders with floating leaves were found only in reference plots and less frequently in farmed treatment plots. In this scenario, increased persistence of exotics and dryland species suggested alternative trajectories. Fields with a short land‐use history (1–3 years of clearing and cultivation) resembled undisturbed floodplain communities, consistent with a ‘field of dreams’ hypothesis. Although river–floodplain reconnections can restore wetlands, legacy effects of past land use may limit the pace and outcomes of restoration.