Basically, Australia's spent the last couple centuries stripping their topsoil for sheep, cattle, and short term (1-generation or less) farms. They have the most garbage soil management program of any major industrial nation on the planet- and there are some bad ones. (The world's total topsoil loss in arable land over the 20th century amounts to over a third of the amount currently in production, so that says a lot.) Using Australia as an example for anything to do with land is highly suspect at best. Hell, the Prosper Australia site you linked me to even says "Under a land tax system, the rural sector would enjoy a lower tax burden, encouraging decentralisation." This could very directly contribute to even further worsening the topsoil of Australia. (If you're really interested, I highly recommend Montgomery's Dirt: The Erosion of Civilization.)

There's no practical difference in collecting tax on land and on resources extracted from land when it comes to historical environmental degradation. We have examples of both methods dating back to the Roman Empire- only direct controls on land use, like preserves and National Parks, prevent environmental degradation of the land.