Project Description
AABR National Forum March 2024 – The Rs of Restoration
Yes it’s all about resilience assessment – but accurate prediction requires ongoing trial and error – Tein McDonald, AABR
Tein McDonald led the team that produced the National Standards. Tein draws on the ecological literature about resilience and disturbance and her experience in restoration of sclerophyll, rainforest and grassland sites in eastern Australia.
The SERA Standards identify four approaches to restoration.
The diagram below shows that the spectrum of degradation is inverse to the spectrum of recovery potential, i.e. the higher the degradation the lower the potential for spontaneous recovery after the removal of impacts. It shows the gradient of natural recovery potential.
Often it is (wrongly) assumed the presence of trees and other native vegetation is a foolproof indicator of buried seed banks – and if regeneration doesn’t happen spontaneously after the cessation of causes of degradation, natural regeneration is not at all possible.
However, resilience is largely invisible, and if spontaneous natural regeneration doesn’t happen after the removal of causes of degradation, this is where facilitated regeneration comes in, meaning that more active intervention is often needed to remove obstacles, recreate conditions and cue germination. A facilitated regeneration approach may be sufficient alone or some level of reintroduction may also be needed, i.e. combined regen/reintroduction.
In recent decades we have learned regeneration potential can extend quite a distance from a remnant if treatments are applied that mimic the natural disturbances and other environmental conditions to which the species are adapted.
My talk – accessible online – draws attention to lessons learned over time about the potential and limits of regeneration beyond a remnant ‘edge’. Two examples are given – one a forested wetland in northern NSW and the other a grassland/grassy woodland in the NSW southern tablelands, north of Cooma.
Gap Road wetland, Woodburn NSW
This site included a previously long cattle-grazed paddock (between two remnant patches) that was entirely dominated by South African pigeon grass (Setaria sphacelata). Searches found only small fragments of three native herbs among the grass swathe and we assumed it would need planting. However, we had the opportunity to conduct a trial burn, so sprayed the tall weed grass to create suitably dry fuel and then burnt it with the assistance of the local Indigenous ranger team who were subsequently engaged to carry out the follow up spray treatments. The regenerators found that some natives emerged from the soil seed bank after the first follow up spray – but substantially more appeared after the second follow up. After 3 years of active follow up spraying, the site had an extensive cover of natives including 21 forb, 7 sedge, 8 grass, 2 shrub and 11 tree species. (Total = 49 species in 0.5 ha)
Scottsdale Reserve Bredbo, NSW
Scottsdale. April 2018 – dominated by Africal love grass – after aerial spraying and before March 2020 fire.
AABR was aware of the results at Gap Road when carrying out AABR’s ‘First Aid for Burnt Bushland’ effort to assist recovery at the property’s long grazed and weed-dominated 5ha Rutidosis Ridge after the February 2020 wildfire. We readied ourselves for intensive follow up spot spraying over a long period and that paid off as expected – around 86 mainly herbaceous native species have returned and weed presence is reducing enormously. What was not expected was the gradual recovery in the ‘buffer zones’ beyond the grassy ‘remnant’ where we thought boom spraying followed by direct seeding of grasses would be needed. Because there were small fragments of quite a few native groundcovers (that could not be sown) the manager decided against boom spraying and sowing, and requested a spot spraying ‘regen’ approach be carried out. This resulted in very high frequencies of 24 native herbaceous species across that buffer zone over 3 years, capturing the site for natives and reducing weed presence.
The site in 2021 after work after spot spraying as part of AABR’S First aid for burnt bushland program.
While it was clear that no planting or seeding was required at all in the Woodburn wetland site or the main core of Rutidosis, we can discuss whether some direct seeding could have been profitably carried out alongside the regeneration intervention in the buffer zones at the Bredbo site. I conclude that sowing was unlikely to have improved the results (as weed control was needed anyway and the early colonisers proliferation in subsequent seasons) – but that reintroduction of missing species may well assist in building diversity in years to come.
While ecosystem type and comparative costs of each treatment need to be considered, the results add weight to the general rule of thumb that managers should always try regeneration prior to assuming planting is needed. This seems to be the case even at substantial distances from remnant edges as long as the soil profile remains intact.
Find out More
The National standards for the practice of ecological restoration in Australia