**Authors Jono Shelley, Tali Shelley, Jeremy Winer

Background

As a consequence of concern over the level of usage of herbicides in public reserves Brisbane City Council has an ongoing pilot program to assess how effective Satusteam™ is as a tool for naturally restoring biodiversity.

Specific agreed objectives of this pilot program between Brisbane City Council and local contracting company Bushtekniq was to observe the results of natural regeneration using manual weeding and Satusteam™ weed management vs the ongoing weed management using herbicides by council employees in Bungwarra Bushland Reserve. 

This poster looks at the comparison of outcomes after 2 years of the ongoing program.

Satusteam™ from Weedtechnics is a unique mixture of saturated steam and boiling water (100C) delivered at low pressure (60psi) to destroy soft leaved and stemmed vegetation of unwanted weeds. 

Its use in urban environments and horticultural applications is widespread, but users of it as a  tool in bush regeneration have observed some unexpected additional benefits over herbicides. The return of volunteer indigenous species, increased ability of endemic ground covers to suppress further germination of invasive species and reduced off target death rates of planted tubestock, killed by overspray of toxins, are 3 key benefits.  Increased soil biology may be a 4th.

Location overview

Barungwarra Bushland Reserve in Bald Hills, an outer suburb of Brisbane in Queensland,  is a bushland and open space multi use park adjacent to the south Pine River.  It was originally a sand mine and unofficial rubbish dump.  Regeneration of the area has taken place over the past 30 years by volunteers, “The Bushies” and Brisbane Council employees and contractors. Bushtekniq,  a brother and sister run company  who are committed to enhancing natural bush regeneration using ecologically sensitive techniques. Since commencing the pilot program in 2020 they have used a combination of manual removal of weeds, using techniques inspired by Joan Bradley,  and Satusteam™ generated by a SW900 from Weedtechnics.

The areas which Bushtekniq have had responsibility for since 2020 are originally formed native planted gardens of mounded site topsoil, planted and mulched in the 1990’s. Invasive weed species had covered between 20% and 90% of the ground surface and under story. The dominant invasive species being, Bidens Pilosa, Dyschoriste depressa, Solanum seaforthianum, Commelina benghalensis.  

Methodology

The pilot program is limited to implementing natural regeneration of species using minimal disturbance manual techniques and Satusteam™ and compared to an ongoing herbicide weed control program. Therefore no mulching or additional plantings were undertaken. The intention is to keep the natural mulch and humus layer intact with minimal disturbance and manage the invasive species to the advantage of the naturally regenerating and spreading endemic ground cover vegetation.

The two pilot program treatment areas were divided into areas to be treated with herbicide and areas to be managed with hand weeding and Satusteam™. These 4 treatment areas were then broken down further into 7 identifying plots, 4 herbicide and 3 non chemical.

Steps taken in non-chemical plots.

• Identify and marker stake endemic species

• Minimal disturbance manual weeding to preserve the natural mulch layer and remove the competition from 10-30 cm around the identified endemic species.  Consideration is given to soil conditions and slope to determine the distance weeded around the endemic plant.

• Satusteam™ weeding of invasive species eg Biden pilosa, done in conjunction with step 2.

• Satusteamed  vegetation left in place to decompose and return nutrients and organic material back into the humus layer.

• Areas then left for the naturally regenerating ground covers and creepers to infill between visits.
• Process was repeated each visit.

Visit calendar

Observations

4 herbicide (HB) and 3 hand weeding & Satusteam™ (SW) treatment plots

In the SW plots there has been a 3.5 to 18x increase in native vegetation cover. In the SW areas volunteer species have appeared including Glochidion, Breynia, native sedges and ground orchid species, as well as fauna including tent spiders, net casting spiders, spiny tailed ants.

The weed cover in all SW areas has reduced by a larger % than HB areas.

Areas of Bidens pilosa that were hand weeded in between native vegetation had a high return of Bidens, probably as a result of disturbing the seed bank.

Areas of established Bidens pilosa that were treated with Satusteam™ had a heavy germination of the Bidens seed bank. This was used as an opportunity to re-treat the areas at 2-4 leaf stage of the seedlings and dramatically reduced the subsequent presence of Bidens . 

Satusteam™ application when controlling blankets of invasive species was measured to be 3 – 5 times faster than hand weeding, with minimal regrowth.

Conclusions

Destruction of the soft leaved and stemmed vegetation using Satusteam™ leaves only decaying matter on the surface of the soil. This is quickly consumed by soil organisms.

The increased coverage of native vegetation in the SW plots compared with the herbicide HB plots indicate that natural regeneration is probable when toxins are not used and natural methods are.

The increased speed of application of Satusteam™ over hand weeding and reduced recurrence of the soft leaved and stemmed weeds after repeated treatments  results in reduced costs of maintenance over time and decreased competition for native regeneration.

When native groundcovers are facilitated to establish, in this case, using hand weeding and Satusteam™ to control competing invasive species, ongoing maintenance costs decrease, soil coverage and stability is improved (this area is in a flood zone) and increased soil microbial activity will likely increase.

Satusteam™ has proved to be an important and valuable tool in this ongoing program reducing costs, labour and efficiencies, without any of the unwanted health implications and environmental costs and effects of the herbicides program.