Gwydir Wetlands: impacts of water regime and grazing on floodplain wetlands

Abstract

Extensive floodplain wetland systems are a characteristic feature of the major rivers in semi-arid regions of Australia's Murray-Darling Basin. Plant communities in these wetlands are dynamic in nature, having evolved under a highly variable flow regime. Their ecology is characterized by pulses of productivity driven by inundation patterns following river flooding. Typical of floodplain ecosystems in many semi-arid regions, they are sites of high biodiversity. However, water resource developments have had a dramatic impact on the flow regime of almost all rivers in the Murray-Darling Basin, holding back floodwaters, and reducing the frequency and duration of floodplain inundation. Environmental flows have been introduced as a means of restoring river-floodplain connectivity with the aim of supporting wetland ecological processes. However, interactions with other land use factors may potentially diminish the benefits of this action. Grazing of domestic livestock, particularly cattle, has taken place on many of these floodplains for over 160 years. In conjunction with flooding and drought, grazing may be one of the most important agents of disturbance that shape floodplain plant communities. This study examined plant communities in the Gwydir Wetlands, an inland terminal wetland system on the Gwydir River in the northern Murray-Darling Basin, Australia.