Floating forest

This page is about a curiosity that came about completely accidentally.

I have a property in Clare in the Mid North of South Australia. The climate is hot in summer (and getting hotter due to climate change), total annual evaporation is about 1.6m and my main water supply, a dam, used to dry up quite frequently before the end of summer. In 2009 I put 2100 floating tires on the dam to cut down on evaporation.

I did not expect trees to take root in some of the tires; not only to take root, but to live for at least several years.

Written 2016/01/15, last edited 2021/07/25
Contact: David K. Clarke – ©

The beginnings of a floating forest
Floating trees
The roots of these trees do not go into the ground
Drone photo
Aerial view of the dam
Floating forest
Some other of the floating trees
The background to the floating tires can be read on another page on this site: Evaporation Reduction on farm dams.

The dam involved was constructed around 1994. Red-gum trees and Melaleuca shrubs were planted around the dam soon after construction to reduce wind velocity over the water and thereby reduce evaporation.

The photos on the right show some of the red-gum (Eucalyptus camaldulensis) trees that have taken root in the floating tires, which are filled with polystyrene. A few Melaleuca trees have also taken root, but have not done so well as the red-gums.

Eucalypts are a very distinctive and unusual genus of tree; very 'Australian'. Red-gums are stand-outs even for Eucalypts; they can grow with their roots completely water-logged for at least several years.

I suppose, in effect, the trees are living in something like a hydroponic growing situation. It is interesting that they must be able to get all the minerals they need from the water in the dam.

Update February 2019

The winter of 2018 in the Clare area of South Australia was very dry. Few dams received any runoff, ours didn't get anything significant. So at the time the photo on the right was taken, 2019/02/22, it was nearly empty; not empty, because of the floating tires, but nearly empty.

Few, if any, of the floating trees had died to this time.

Click on the image for higher definition.

Update September 2019

The rainfall for 2019 to the present had been more than 100mm below average and there had been very little run-off into this dam. Fortunately there had been a good amount of catchment into another dam (another story there altogether) and I was able to syphon that water into this dam over the couple of weeks before this photo was taken.

Again, few trees had died, even though some of them had been completely out of the water for several months. They had put roots down into the damp soil. Some of them had roots holding on to the soil strongly enough to almost stop the tires floating with the rising water.

One or two of the trees were becoming large and heavy enough to start tipping their tires over (one such in the left foreground of the photo). I'll probably prune these back.

Click on the image for higher definition.

Update late July 2021

While I have not kept records I estimated years ago that the dam filled in about two years out of three. It has not come close to filling in the last five or so years.

My opinion is that climate change must be a factor in this. Higher temperatures, lower winter rainfalls.

Many of the redgums are still doing well.