TREAT Info-Notes | Replanting the Rainforest No. 1

Planning with a purpose

Replanting the rainforest needs planning with a purpose to get the right tree in the right place for the right reason at the right time.

Background

Tropical rainforests contain the greatest number of different plant and animal species (ie biodiversity) of all types of land use. The Wet Tropics contain the greatest concentration of primitive families of flowering plants in the world, and some of the nearest surviving relatives of the ancestors of Australia's present-day native animals and insects.

The area of tropical rainforest in Australia has been decreasing for thousands of years, caused mainly by changes in climate but more recently due to human activity. Now all that is left are a few large continuous areas and many smaller isolated patches or remnants.

Clearing the rainforest means loss of this biodiversity of species and of our natural heritage. Remnants may be too small to support many species, or they may be too far apart to allow easy reproduction of some plants, animals and insects. Replanting corridors to connect these remnants or increasing their size can help to restore the biodiversity of the whole area as well as within the remnant.

Improved land management

Planting corridors of rainforest along the rivers and streams can decrease erosion leading to better water quality, and provide windbreaks for agricultural activities. Repairing and maintaining existing forest preserves the present ecosystem and provides recreation areas for people.

Replanting the rainforest

Your success in replanting rainforest species depends on how well you know your natural environment - soils, climate, height above sea level, rainfall, land forms - and the problems caused by erosion, weeds, and loss of fertility. Each environment has a set of species that grow best there and will be most suited to the local soil type, aspect, slope, altitude and drainage. You will need to choose the right species for the right place - so get to know your environment, before you start.

Your site

If the area you wish to replant has been degraded by loss of fertile topsoil from erosion, or is naturally infertile, fertiliser can help trees off to a good start. Also, you may need to provide structures to prevent further erosion to the site while the trees are small. If the area is infested by weeds (a weed can include everything from a grass to a tree), you will have to remove or kill them to allow your small trees to become established. If you have grazing animals, they will need to be excluded by fences.

Understanding plant succession

The species that make up one type of rainforest in one environment can change from time to time as the forest ages from young-forest through to mature-forest and old-forest. This change in species within one type of rainforest is called 'plant succession'. If you look at the edge of a rainforest or inside when an old tree falls and dies, you will see plant succession in action. On bare ground or at the edge of the forest, the first species to grow are the grasses and broad-leafed, non-woody herbs. These are followed by woody shrubs such as lantana and tobacco bush, which are replaced by small hardy trees known as the pioneer tree species which can grow readily in full sunlight. These pioneer tree species provide the shelter required by the secondary tree species to become established. As the forest matures, many of the pioneer tree species and some secondary tree species are replaced by vines, ferns and other tree species which become established by seed dispersal from nearby rainforest areas.

Understanding landscape restoration

Consider how your replanting efforts will fit within the local and regional landscape. You will need to consider the size, shape, fragmentation and linkages of your site. The ideal shape is as big an area as possible, providing the largest amount of interior habitats and the smallest amount of edge habitats. Corridors of forest provide an avenue for the exchange of existing, and recruitment of new, plant and animal species between fragments of rainforest. TREAT has promoted corridors of forest along existing streams as a method of linking forest remnants, controlling weeds along streams, and preventing erosion of stream banks.

Plan your method of revegetation

To successfully replant a rainforest, you will need to consider at what stage of the plant succession you wish to start.

The framework species method

In this method, one or a few quick-growing species are planted to provide a leafy closed canopy within about 12 to 18 months, shading out weed species and providing a framework under which other species can become established. Typically a mixture of pioneer and secondary succession species are used, which fruit young and attract birds and animals to feed and disperse seeds from nearby rainforests.

The maximum diversity method

In this method, the bulk of the species are from the mature-age forest in an attempt to recreate the original diversity of species in one go. This method is more successful when the site is small or far removed from other rainforest areas, such as urban locations, council parks, golf courses, and rural residential allotments. A disadvantage is the slower growth rate of many mature-forest species which requires greater attention to weed control and other post-planting care.

The natural regeneration method

This method is a speeded-up version of natural plant succession. Fire is excluded by firebreaks, grazing animals are controlled by fencing and noxious weed species are removed. Regeneration of the forest then relies on the germination of seeds of native species stored in the soil or spread from nearby rainforest areas. This method is suited to repairing the margins of existing forests, or stimulated regeneration of areas close to existing rainforests.

How do I achieve my plans?

Special attention must be given to planning the project.

  1. Discuss the whole project with the property owners if you are not the owner, and with the neighbours. Seek advice from local community groups, government organisations and technical advisers.
  2. Consider the 4 R's - the Right tree in the Right place at the Right time for the Right reason.
  3. Questions
    • What are the right species for each environment on my site?
    • Where will I obtain the trees, or should I germinate my own seedlings?
    • When is the right time to plant them?
    • How and who will plant them?
    • What are the costs?
    • Who will do the post-planting maintenance?
    • Who will do the post-planting monitoring of plant and animal recruitment?
  4. Map your site, marking soil types, drainage lines, access needs for vehicles and animals, fences, present vegetation.
  5. Research the history of your site, noting previous floods, previous vegetation, and previous land uses.

More Info-Notes

  1. Planning with a Purpose (this page)
  2. Preparing the Groundwork
  3. Planting Out
  4. Maintenance and Monitoring
  5. Planting in a Riparian Location

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