Category Archives: Rainforest

Rainforest restoration on private land – Wompoo Gorge, Huonbrook, NSW

 Key words: Rainforest restoration, assisted natural regeneration, Lantana control, threatened species conservation

Maree Thompson

Wompoo Gorge is a private property located at Huonbrook in the Byron Shire hinterland, north coast NSW. The property provides a link between Nightcap and Goonengerry National Parks with Coopers Creek running along the eastern boundary. Originally covered by lowland subtropical rainforest with a stand of eucalypt forest extending down from the 100m high escarpment, half of the site was cleared early last century and partially converted to pasture and banana plantations. At the commencement of the project, the area contained various stages of rainforest regeneration and dense infestations of Lantana (Lantana camara). Twenty-seven threatened species (10 threatened flora species and 17 vulnerable animal species) have been recorded at Wompoo Gorge. The site has exceptional restoration potential and overall conservation significance.

Lantana infestation before works

An ongoing ecological restoration project is being implemented at the property, based on the recommendations of the Wompoo Gorge (South) Restoration Action Plan. In the three years to date, dense areas of Lantana in the area originally cleared have been controlled by mechanical means. A 4-wheel drive tractor was used to drive over and flatten Lantana over 2ha, returning a few weeks later to slash the Lantana. This method (first developed by Ralph Woodford at Rocky Creek Dam) resulted in the death of the majortiy of Lantana treated. Care was taken to aviod any existing regrowth of rainforest species near edges and regrowth patches.

Bush regeneration works have now been extended over an additional 14ha. A range of weed control techniques (including overspray and use of a splatter gun) have been used in the denser areas of Lantana not accessable by tractor. Hand weeding with brush hooks and loppers and cut/scrape and paint of Lantana is being undertaken in the more lightly invested native vegetation. Fruits from native plants on site have been collected and spread through out regeneration areas, adding to seed in the soil bank and that which is naturally distributed.

Tractor clearing of Lantana

A monitoring program was established on site prior to the commencement of works. This included eight monitoring transects. Structural and floristic information was collated and photos taken prior to the commencement of works and then at the end of the first year. Data were entered into MERV (Monitoring and Evalution of the Restoration of Vegetation) database and used to produce reports.

From Lantana to bare ground in Year 1

Results. The previously dense Lantana areas have converted from weed to strongly regenerating rainforest by means of natural regeneration occurring over the 3 years since treatment. The areas first treated in Year 1, in particular the area where a tractor was used to control Lantana, have had impressive growth of native species, now up to a height of over 5 metres. Common regrowth species include White Cedar (Melia azederach), Trema (Trema tomentosa), Red Cedar (Toona ciliata), Tamarind, Sandpaper Fig (Ficus coronata), Bangalow Palm (Achontophoenix cunninghamiana), Brown Kurrajong (Commersonia bartramia), Stinging Tree (Dendrocnide excelsa), Pencil Cedar (Polyscias murrayi), Celerywood (Polyscias elegans), Blue Quandong (Elaeocarpus grandis), Black Bean (Castanospermum australe) and Sally Wattle (Acacia sp.). A strong mix of later phase rainforest species are also germinating. Groundcovers include Soft Braken Fern (Culcita dubia), Cunjevoi Lily (Alocasia brisbanensis), Juncus spp., Cyperus spp. and a range of basket grasses (including Oplismenus spp. and Ottochloa gracillima).

Regenerating natives at the end of Year 2. By the end of Year 3 it was difficult to get a view above the regenerating trees to take overview photos.

Lessons learned. As with all projects, follow-up weed control is essential to ensure that native species come to dominate the site in the long term. The project has recently gained funds to continue the works for a further 3 years. This will allow the project to to continue works into nearby areas where it is known that significant and sustainable environmental outcomes can be achieved on a cost effective basis.

Funding. The project is funding by a 3 year NSW Environmental Trust project with addtional support from the 2010 DECCW Great Eastern Ranges Initiative-Connectivity Conservation Incentives; the Northern Rivers CMA Invasive Species Weeds of National Significance program, and the EnviTE Jobs Fund and Green Jobs Corps teams. Further funding has been gained through the Raymond Borland Bequest Grants program and the Big Scrub Rainforest Landcare Group’s Caring for Our Country project.

Contact: Maree Thompson, EnviTE Inc, 56 Carrington Street (P.O.Box 1124), Lismore NSW 2480; Tel: +61 2 6621 9588, Email: mareet@envite.org.au

Thiaki Creek: Cost-effective Rainforest Restoration for Carbon & Biodiversity

Key words: landscape resilience; rainforest fragments; connectivity; endangered species

Noel Preece

A large-scale reforestation experiment has begun in the Wet Tropics to examine the best and most cost-effective ways of reforesting a long-cleared grassed landscape to rainforest. The project is on Thiaki Creek, a highland tributary of the North Johnstone River which flows onto the Great Barrier Reef of Far North Queensland. The project is based on a fully replicated experimental design of 64 plots, covering over 20 hectares.

Part of the 20 ha experimental area in which the 64 plots are laid out. Rows were sprayed to suppress the exotic pasture grasses and the planters are planting the seedlings directly into the ground with planter spades.

The local ecosystem is moist complex notophyll vine rainforest (type 7.8.4) which can be seen in the background. This is State-listed (endangered) rainforest, home to endangered Cassowaries and six species of possum, and more than a hundred species of bird including the rare Grey Goshawk.

Aims: While forestry practices using monoculture tree species are well developed, reforestation practices using mixed native species for carbon sequestration and biodiversity are relatively poorly understood. Results of mixed plantings have been variable, regularly producing less than optimal outcomes and high establishment and maintenance costs have resulted in poor returns from investment. This is due to inadequate research on optimum site preparation, species mixes, spacings and propagation to achieve more cost effective outcomes.

Results and lessons: 27,000 trees were planted in January 2011, a few days before Cyclone Yasi. Early lessons learned are that spraying pasture grasses in strips, rather than blanket spraying the whole planting area, provides protection from erosion, wind and desiccation. Planting when the ground is saturated improves survival rates. An early experimental result demonstrates that forestry planting methods using planting spades take ¼ the time and 1/6 the expense of using augers, a common practice among landholders in the region, and the responses of mixed rainforest species is very good, with less than 6% loss.

Future directions: A range of studies has commenced on the site, including studies on soil carbon and nutrients; above ground carbon; plant diversity and plant functional traits; bee, fly, ant and dung beetle diversity and function; review of restoration practices; and economics. Future studies could include vertebrate roles and responses; competitive effects of tree mixtures; relationships of spacings and species to site capture rates and natural suppression of grasses; diversity versus productivity and resilience; mycorrhiza and other soil microbiota studies; soil hydrology and micro-climatology.
Stakeholders: The project is supported by a 5-year Australian Research Council Linkage grant, with the Universities of Queensland, Adelaide, Charles Darwin, Cambridge and Lancaster and Linkage partners Stanwell Corporation, Terrain NRM Ltd, Greening Australia and Biome5 Pty Ltd.

Contacts: Dr Margie Mayfield, University of Queensland, m.mayfield@uq.edu.au; Dr Noel Preece, Biome5 Pty Ltd, noel@biome5.com.au. Outlines of the Thiaki project are shown on: www.biome5.com.au/page/thiaki.html and www.mayfieldplantecologylab.org/site/Thiaki_Project.html