Regular readers and supporters of our farm will be familiar with the challenges we’ve faced trying to re-establish native vegetation in the face of large populations of rampaging herbivores. Inspired by an idea from @nature_at_work_ (check them out on Instagram) and folks around the world working to increase urban and rural habitat, we thought we’d construct a floating habitat island.
Once installed in the dam, we hoped the island would function as a seed bank for aquatic plants, a fox-proof roost for waterbirds, and offer filtration through the plant roots as well as aquatic shelter and habitat.
During the summer, our friend Shani, assisted by a team of kids, got to work assembling a frame from some leftover PVC stormwater pipe to act as the float, with a length of shade cloth salvaged from our gully junk to act as a base onto which we could later plant local aquatic plants. The frame was tied to a rock anchor and then launched with great ceremony.
In the following months, the island became popular with waterbirds of all types, with ducks often spotted perched on the floating edge, grebes diving underneath and the enclosed centre of the island becoming coated with feathers and bird manure.
After propagating a selection of aquatic plants from seed collected elsewhere on the property, and supplemented with a few other species from State Flora, in winter, Shani and her team returned to plant the prototype island out. Using coconut fibre and soil as a growing medium, the island was vegetated then dragged into position once more.
The prototype was a beautiful thing, but unfortunately, not yet fully farm proof. Within a couple of weeks after its launch, all of the new plants and the growing medium had disappeared, leaving the habitat island defoliated once again! We’re a little puzzled by their disappearance. A week of heavy rains followed the planting, so it’s possible that as the dam water level rose, stretching the anchor rope to its limit and tilting the island so all the plants and growing medium floated out. Or maybe it was just body-slammed by every duck on the Fleurieu, catapulting the aspiring wetland plants into the dam.
Whatever the case, we’re looking at tweaks for the next attempt. This island installed in Orange, NSW, has the growing area covered by what looks like a bird excluding mesh, which may be worth considering until the plants are well established and their roots have pushed through the shade cloth base. I notice that some designs also have the growing medium contained in some kind of textile, with holes punched into the surface for planting. Perhaps we could try planting through hessian or covering the plants and growing medium with a fine mesh to hold them in place. Another option is to establish the plants in a more controlled environment (eg. an old bath) until their roots have bound the soil to the island itself before launching. We’ll keep trying!
Thanks to Shani, Freya, Arlo, Pete and Innis for their persistence and good work!