Leaf litter dynamics and the rehabilitation of degraded coastal rivers in NSW, Australia

Abstract

Heterotrophic energy pathways play an essential role in the integrity of forested stream ecosystems. In these rivers, leaf-derived energy is assimilated by biota at low trophic levels which is then made available to higher-order consumers by predator-prey interactions. The availability of resources is governed by two key processes; the retention of leaves by physical structures, and the processing of leaves by microbial degradation, and mechanical and biological fragmentation. The reliance on leaves means anthropogenic disturbances such as the clearing of riparian and floodplain vegetation, recolonisation by invasive plants, and changes to in-channel structural complexity can lead to fewer resources for leaf-dependent consumers. Rehabilitation has the potential to restore critical ecosystem functions, although these indicators are seldom included in rehabilitation projects. This thesis examines the potential for rehabilitation with engineered log jams (ELJs) and riparian replantings to rehabilitate detrital energy pathways to degraded coastal rivers.