Seasonal Herbaceous Wetlands

by Alan Hewett, Chiltern Landcare member

During winter or spring you might see puddles in a paddock or along the side of a road. On closer inspection you will find an array of brightly coloured Billy-buttons, Early Nanciesor Swamp Daisies. You could stumble upon Fairy Aprons, a beautiful purple colour but with a dark secret-they are carnivorous, trapping insects with an ingenious bladder device. All these native herbs are indicators of a Seasonal Herbaceous Wetland.

These wetlands are limited to the temperate zone of mainland south-eastern Australia. They only occur on flat plains below 500 metres. They rely on rainfall as their main water source and are not dependent on flooding from rivers. They fill in winter and are dry in summer. They are small, 60 % of these wetlands are less than 5 hectares in size and unfortunately few remain in good condition.

Besides the native herbs, these wetlands also feature a variety of native plants. One is Milfoil, once eaten by Aboriginal people as a bush food. Then there is Nardoo, an aquatic plant that looks like a four leafed clover. This was also used as food by Indigenous people, who discovered it was toxic unless soaked and cooked properly. It is believed that Bourke and Wills died from eating untreated Nardoo as it inhibits the creation of vitamin B1.

These wetlands are vital in improving water quality. They help to remove impurities ranging from sediment to pesticides. They help to mitigate flooding and are a haven for important aquatic insects, crustaceans, frogs, reptiles and water birds.

Because of the seasonal nature of their existence these wetlands are threatened from a variety of sources: weeds, stormwaterinput, slashing, cropping and grazing. The biggest threat is global warming. The wetlands will remain dryer for longer periods and subject to destruction, although they can recover after long periods of drought. Rhizomes, root stocks, bulbs and seeds can regenerate, 75% of wetland species will germinate after six dry years. However, these wetlands are now considered critically endangered.

The majority of seasonal wetlands are on private property. Measures can be implemented to protect them. Buffer zones consisting of woodland communities can surround the wetland. Fences can be erected to keep stock out. It is mainly due to the efforts of dedicated landowners that these wetlands still exist.

So if you see puddles in a paddock, have a closer look, you might be able to save something precious.