29th December - Reverse Succession

The concept of "succession" is used to understand how the bushland became what it is today. Bush gardeners are more interested in what their bit of bush was like 200 years ago. Since much of the destruction of our bushland occurred fairly recently it helps to understand what has occurred over the last 50 years.

An understanding of this can be obtained with the concept of "reverse succession". Suppose that you start with any block of land and start a list.

Firstly list all the plants that occur on the block in order of dominance. Next remove all the plants on the block. As plants germinate remove them and add them to your list in order of dominance if not already included. Keep doing this until no further plants germinate. That is the soil seedbank is exhausted.

Reading your list from the bottom will then give you a reasonable idea of the order in which the plants disappeared from the block of land.

This concept also helps in understanding what is needed to restore the land. This is really what you are attempting to achieve in bush gardening except you do not remove all the plants. The idea is to remove those plants that allow the desired plants to return.

It is clear that all non-indigenous plants should be removed but this concept may help in understanding why it is necessary to control some indigenous plants.

Once the naturally occurring events that guided the makeup of the bushland was replaced by artificial events such as cattle grazing replacing wallaby grazing and cold burns replacing hot burns etc, some indigenous species were just as capable of becoming abundant as introduced woody weeds and grasses.

It is not hard to find blocks of bushland in the Adelaide Hills which are virtual monocultures of indigenous plants. I know of one block that is nothing but Platylobium obtusangulum for example. Although this may be satisfactory for the bush carer, it is hardly satisfactory for the bush gardener.