Wetland vegetation of inland Australia

Abstract

Wetlands fed by rainwater, surface flows and groundwater occur throughout Australia, even in arid areas. This chapter focuses on temporary wetlands and permanently wet systems that are dominated by non-woody macrophytes. We use nine case studies that span Australia to illustrate their biogeography, dynamics and key threats of Australian Wetlands. The type and distribution of wetland vegetation, from the annually flooded wetlands of northern Australia, to saline lakes of arid and semi-arid Australia, to groundwater-dependent systems of the southwest, to bogs and fens of the Alps and Tasmania, reflects hydrology, climate and geomorphology. Wetland plants have developed a range of adaptations and life histories to tolerate the dynamic water regimes characteristic of Australian wetlands, and can be grouped into seven categories that reflect these adaptations. Waterbirds and water can connect spatially isolated systems, and seedbanks that last for decades allow species to disperse through time. The water regime is a strong driver of species composition and abundance, thus hydrological modification through water extraction, flow regulation or reductions in rainfall is a significant threat to wetland flora, and arguably the principal threat for Australian wetland vegetation. The displacement of native macrophytes by exotic and terrestrial species is both a symptom and cause of ecological change, with exotic plants often being better adapted to modified flooding and fire regimes, livestock grazing and eutrophication than natives. Introduced livestock and feral fauna eat, trample and uproot native plants, and degrade their habitat. These types of threats are expected to intensify, increasing the challenge for wetland management and policy.