Bushland Restoration at Kings Park Botanic Garden, Perth, Western Australia

Kings Park Botanic Garden in Perth cover 1000 Acres (or 400 Ha) . The site is 1 kilometre from the centre of Perth and gets about 5 million visitors per year. However, most do not visit the bush – they come to see the views, freesias and developed gardens.

A major achievement in recent years has been the Plan of Management for the park, which included the management of the bushland areas.

Previous fire frequency was one of the major problems. The park has around 50 years of fire records, at one time about 1/3 of the park was burnt each year under planned burns. Wildfires were in addition to this.

The bushland has a heavy litter layer and consequently recommendations were made to carry out hazard reduction burning every 2 to 3 years. However such a fire regime would result in high levels of weed growth, with the weeds carrying fire more regularly, and the potential loss of indigenous plants. Fauna studies also indicated that burning should not be this regular. A seminar on burning was held which helped to change attitudes to regular burning. Kings Park now has an ?integrated fire management plan’ which includes its own fire units, a close working relationship with Fire and Rescue, and reducing fuel levels by controlling environmental weeds.

Perennial Veldt grass (Ehrharta calcyina) is a major problem, which was exacerbated by frequent fire. With the reduced burning this has been dealt with by spraying using grass selective herbicides such as Fusilade 212.

Two other problems addressed by the Bushland Management Plan were the reduction of the large number of tracks (39 km); and removal of a lot of non-indigenous eucalypts which had been planted to beautify the bushland. Some of these trees have been felled and the mulch used on degraded sites, mainly to control weeds, where no indigenous plant seed is stored in the soil.

In order to maintain diversity and genetic integrity, commercial seed collectors are not used as it is too costly for them to collect small quantities. The park has now trained up its own seed collectors, which has proved to be cost effective. A database is maintained recording details of species, the location, time when seed should be ready to collect, and viability of each seed batch. The park also has a unit to allow tissue culture, but this propagation technique limits the genetic diversity and is costly.

Some DNA testing is also being carried out which if necessary allows seed to be sourced outside the park, at present only 5 species are collected in other areas. It was assumed that species from the Swan Coastal Plain would be similar in genetic makeup but genetic studies have found that some populations are quite distinct. There are 6 priority species in the park, with some being ?type’ specimens that were collected by early botanical collectors sailing up the Swan River.

Scarp Restoration Program
The Scarp Restoration program is for an area covering around 19 hectares, above the Swan River, which has a long history of disturbance. The restoration program has involved the removal of woody exotics and revegetation. The program is costing $50,000 to $75,000 per hectare to restore. WMC (Western Mining Corporation) has provided $610,000 (which includes $210,000 in kind) and the state government is providing $4million over 4 years.

The funding was divided between 1/3 bushland restoration; 1/3 heritage work and 1/3 on safety works. For example about $500,000 was spent on a safety fence to stop rocks falling on a road. Another safety feature is a constructed limestone wall preventing a rock overhang from falling, over 20 tonnes of rock was used, leaving deep crevices which created native snail habitat.

Planning and research has been carried out prior to the commencement of work. The seed bank is tested by skimming off 5cms of soil, treating with smoke to stimulate seed germination, and putting it in the glasshouse to see what seed is stored in the soil.

Research also identified which species had tensile roots and would be good to use on the steep slopes to hold the soil together. All the species used are propagated in 3 or 4 Accredited Nurseries to reduce the risk of introducing root pathogens and new weeds into the bushland. Plants are grown under contract by the nurseries and regular inspections are done to make sure they adhere to the strict contractual agreements.

Cultural heritage assessments were carried out prior to selecting exotic trees which were to be removed. Tree contractors are used to fell the exotic trees. As part of the work they are required to write a fauna protection plan, in particular to protect the rare scarp snail and trapdoor spiders.

Money was spent on looking at the heritage trees eg Phoenix canariensis along the old tramway, most of these were left. Self-recruited pine trees were removed after determining by drilling and ageing which were siblings rather than the original plantings. Many were also removed for safety reasons. The site is worked in zones, and a certain number of zones are worked each year.

A reticulation system has been set up as the project cannot afford to lose too many plants, (normally no water is directed to bushland areas or revegetation sites near bushland). Soil wetter is sometimes used, but not gels. Organic fibre matting is used to provide stability and reduce erosion, presently we use more coconut fibre with 30% goat hair and knitted on the back. This is made locally and though a little more expensive lasts longer and retains its colour.

A lot of assistance has been given by volunteers, government departments such as Perth Zoo, Department of Environmental Planning, Green Corps and Work for the Dole, corporate assistance eg WMC, Woodside Petroleum, The Body Shop as well as students from universities and the TAFE system. This is successful by because of a high ratio of supervisors to participants (1 supervisor per 5 participants)

Herbicide trials have also been carried out.

Weed control methods
Bridal Creeper: The spread of Bridal creeper is being held by the use of leaf hopper in some areas but has not yet been used in Kings Park as we have a large spraying program. Bridal creeper rust has been introduced but at this stage does not seem to spread as quickly as anticipated. Control is also by spraying with Brush-off. Although this kills at 1g/ha, 2/5g/ha is used. At these low rates there is very little damage to native plants, although there appears to be a problem with one species of Fabaceae Templetonia retusa, where the pH is high.

Spraying is done before planting, and there is only a narrow window of opportunity. There is not enough time to spray twice. The metasulphuron breaks down quickly in acid soil. Any problems at these low rates with alkaline soil are not evident yet.

Hot fires have also been found to kill the parent plants and the seed bank of Bridal Creeper (fortunately under normal conditions the seedbank only appears to last for 3 years) so after fire any reshooting plants are sprayed or removed with a mattock.

Spraying is done by contractors, who are very good. A premium price is paid for the quality work ($60/hour). Independent consultants monitor the spraying ie death rates, all quadrats are located using a DGPS. The whole of the park, excluding the Scarp has DGPS location points, in a grid formation. They are set up every 100 metres using star pickets with the coordinates marked on a small plate welded on top of the picket. This enables you to find things much easier than using a compass. Dye is used when spraying to enable you to see what has been sprayed, for this purpose it must last 2 – 3 weeks.

Other weeds

• Euphorbia terracina (Geraldton carnation weed): is potentially a bad weed so an eye is being kept on this. Generally treated by spraying the first time and then hand removal -but many people are allergic to this plant.
• Agave: is treated by first soaking dowel rod in Garlon and then hammering the rod into the center of the plant, after the top has been cut off. In this way the herbicide diffuses through the plant.
• Romulea rosea: this is sprayed with Brush-off during early flowering period.
• Other bulbous plants eg freesias and gladiolus, are sprayed mid-flowering.
• Ehrharta calcyna is a major weed. It will carry a fire every year and takes a lot of moisture out of the soil. It produces a lot of seed which can germinate even when 5 cms below the soil surface. Fusilade is used to control this weed at 4l/ha. Most is absorbed within 1 hour of spraying. This herbicide is used in bushland as it does not seem to harm most other species, including orchids and proteaceae. The spraying needs to be carried out when the plant is actively growing, which is from June to mid-August in WA.

Along tracks a machine with a ?wet blanket’ can be used for controlling any weeds but is very good for controlling bulbous weeds. The height of the blanket can be adjusted so that the herbicide does not touch the soil.