Brisbane Rainforest Action & Information Network

A thinking regenerator in Brisbane

Robyn Becket

This article describes the natural regeneration of more than 80 native species on a 2 hectare site over a period of three years. The site is located between 100 and 300 metres north of the South Pine River, in Draper, (about 5km North east of Samford and approximately 20 kms NW of Brisbane CBD).

The land, which has a mostly southerly aspect, has one gully passing through it with another short gully linking into the first. Over most of the site the original soil is intact. When we took possession in late 1994, approximately 20% of the land had indigenous trees, including a group of mature Hoop Pines (Araucaria cunninghamii) around the gully and a few trees on fence lines and isolated paddock trees. The land was grazed by beef cattle before the developer subdivided it, put in culverts and cut and filled across the gully to allow access. For a year or so (before we took possession) the land was regularly mown, to look like rolling parkland. Whilst we did not get the land slashed we did have a horse grazing some of the land for about a year. Other changes to the property included earthworks done for a house and drive and construction of a dam.

As slashing and grazing stopped, species suckered or regenerated from seed. Seedlings grew under the remnant shade trees, from seeds of the parent tree and from those dropped by visiting birds. A huge setback, after a year of our new regime, was coming home one evening to find that nearly an acre of regenerating Silky Oaks (Grevillea robusta) had been slashed! Samford Valley is also known as "The Golden Valley" after the indigenous Silky Oaks and these young trees were progeny of a tree we had cut down to make space for our house. They, along with several Hickory Wattles (Acacia aulacocarpa) and a Cheese tree (Glochidion ferdinandi) were about half a metre tall. The tractor driver appeared to think that even if he had strayed off the land of those employing him, he would be doing someone a favour.

Hickory Wattle is the most numerous regenerating tree. Growing quickly and close together, it forms a windbreak and provides some shade for other plants. I have heard that this species can live for 60 to 100 years. After 3 years the tallest of these is about 5 metres tall. It is often said that these wattles, along with the similar looking Blackwood (Acacia melanoxylon) prevent natural regeneration, but I have many plants growing under their protection. For example, two young Hoop Pines have grown from about 30cm to over 4m by the stump of a Jacaranda, surrounded by young Hickory wattles and a Foambark (Jagera pseudorhus). However, it varies and there is often bare soil in a ring around the large trees under the drip line. I have killed some Hickory Wattles in the house garden, which is primarily for growing food, and the fruit trees and grass nearby have flourished.

The fastest growing regenerating species is Green wattle (Acacia irrorata); germination has been triggered in most cases after earthworks. The tallest Green wattle is about 6m.

Lantana and other weeds proliferated after slashing stopped. After clearing some of the Lantana, I realised that the small rainforest seedlings needed its protection, so it was kept and slowly cut back or killed in situ. This also helps protect wildlife. I am now clearing the Lantana from under the Hoop Pines and so far have found very little regeneration beneath them. However, regeneration of species beneath the Hoop pines occurs soon after the lantana is removed. I am continuing with the gentle control of Lantana in more open areas.

Initially, I did plant several trees around the fence lines and near the house for privacy. However, the thickets of fast growing Hickory wattle have provided privacy as quickly as planted Eucalypts. Near the house, the tallest and bushiest trees are naturally regenerated Green wattles, growing with planted trees.