London Creek Case Study

Comparing Mechanical Disturbance for Regeneration

Appropriate Disturbance

Can certain forms of soil and vegetation disturbance in natural areas actually be a positive intervention to achieve a site’s restoration goals?

In contrast to earlier disciplines of ecological restoration that implied a blanket ‘minimal disturbance approach‘ – in some situations and soil types – intentional or opportune disturbance events can be a positive interaction. And more so, can greatly assist with a more rapid transition process in disturbed habitats – both in terms of weed control and re-engaging native regeneration through seedbank restoration.

London Creek Case Study

In 2012, Bushcare Services was engaged by Sunshine Coast Regional Council to assist in a regeneration project located in the London Creek Environmental Reserve; Peachester. This 146 Ha property acquired under the Sunshine Coast Council’s Environmental Levy Acquisition Program, comprises significant natural values, rare and threatened species with ‘of concern’ Regional Ecosystems.

Restoration works were planned in a weed-disturbed parcel of the property that consisted of large lantana stands in a lightly wooded area – adjacent to remnant riparian vegetation. (RE 12.9.16) The site was selected for a trial due to its high resilience and insitu native seed bank.

Integrated Methodology

Initial works involved the cutting in of access tracks between stands of lantana, which would in turn act as the buffer between the various treatment zones.

  1. Alternate stands of lantana were treated making use of the splatter gun technique at a ratio of 1:9 (Glyphosate). The rationale behind this was to not clear too much too soon.
  2. Whilst waiting for lantana to die off, works involved hand preparation in the good nodes of natural vegetation, freeing up the natives and to retain refugia for small vertebrae fauna, particularly birds.
  3. One of the zones was identified and flagged for the SCRC to bring in a forest mulcher/posi trac and knock down all treated lantana and shallow rip the earth when done. The Lantana biomass was raked clean -roots removed.

Results

Six months preceding the initial treatment, there was little regeneration coming up in any of the manually treated control zones. Comparatively, areas which had been cleared and shallow ripped with the posi-trac however, featured strongly with rainforest pioneers including densities of trema tomentosa, Homalanthus populifolius, Macaranga tanarius and Stephania japonica. 

Re-visiting the site 12 months after initial works, the manually treated plots showed a slower, delayed regeneration process occurring – with a noted greater diversity of rainforest sp. At the same time in the mechanically treated plot, the disturbed area had been completely captured by native regeneration, with the above mentioned species in excess of 2 metres tall.

The results clearly showed that this selected site responded more favourably with a higher level of mechanical disturbance offered with the forest mower. If the purpose of the trial was to rapidly capture the site with endemic regeneration, this method was more superior and required less manual maintenance to achieve this result. Comparatively, the outcomes in the manually treated plots were successful with a more a more biodiverse outcome. However, a slower site capture, left it more vulnerable for competing weeds to germinate and thus required more manual resources to maintain.