Crouching frogs and hidden wetlands

Crouching frogs and hidden wetlands

Mortlake swamp daisy

Swamp daisy (Alittia cardiocarpa) at Mortlake Common

If you’ve spent any time on the highways recently, you may have been happy to notice that many of the wetlands that have been dry over the past couple of years have been receiving good amounts of water.

But some wetlands aren’t so easy to see. Out at our project site at the Mortlake Common Flora Reserve, the large (~25 hectare) grassy wetland in the middle is beginning to fill, and aquatic species are appearing again. The funny thing at Mortlake is that apart from the croaking of frogs, you don’t tend to notice the shallow wetland til you’re almost standing in it, as most of the time it hides below water tolerant grasses and sedges.

This plains grassy wetland vegetation community at Mortlake is one of the rarer vegetation types found in the region, with drier up-slope plains grassland species grading into amphibious grasses and herbs at the water’s edge, and then into aquatic vegetation in the deeper (but still relatively shallow) water. The changing soil and moisture conditions are a recipe for diversity and help to make Mortlake Common one of the most valuable grassland sites in south west Victoria, home to the only known population of the western gaping leek-orchid (Prasophyllum sp. aff. correctum) and a potential site for the growling grass frog (Litoria raniformis) which has been spotted there in wet years.

Our project – funded by the Victorian Government through the Department of Environment, Water, Land & and Planning (DELWP) – has managed to implement a number of critical weed control and monitoring actions that will help to secure the threatened species populations found at the reserve.

One of the interesting man-made additions to the Common is a shallow drain running from the wetland into Blind Creek, which passes through the reserve. We’re currently exploring the possibility of further restoring wetland function by removing the influence of the drain. You can spot the scar running from the south east of the wetland in the aerial image below, from October 2011. Wouldn’t it be nice to turn back time? I’m sure the growling grass frogs would agree!

Mortlake drain

Mortlake Common drain running south-east from the wetland to to Blind Creek (image: Google Earth)

Jonathan Tuck