Jennifer Firn, Queensland University of Technology

This season’s terrible bush fires present many options for conservation and restoration action. Here I want to present the idea that one of these options is to explicitly concentrate on restoring native grass species in grassy ecosystems.

I have been working on aspects of restoring grassy ecosystems and native pastures impacted by the invasive grass species Eragrostis curvula (African lovegrass) since the start of my PhD in 2006. Back then, I never would have predicted that I would work for so long on African lovegrass, but its impacts are so severe that it is hard not to continue.

When I was starting my PhD, I could choose any invasive non-native plant I wanted to work on, as long as it was in a certain part of Queensland. I took this decision very seriously and went out and met as many people as I could to weigh up a range of options. The reason I started working on African lovegrass came down to ecological but also social and economic impacts. Farmers on the Darling Downs were very concerned about its spread and I remember how distressed people were at the time as they felt no one seemed to be listening to them. There also seemed to be no clear answer for managing this species, with the restoration challenge being bigger than the grass itself. I learned from the beginning of my PhD, because of my supervisor’s impactful research and insight, Professor Yvonne Buckley (now at Trinity College Dublin), that invasive plant control was a more complex issue then targeting the individual species itself, let’s face it, there are numerous ways to kill an individual plant but time and time again it does not work at the community level. Because of this complexity, I also learned how much ecologists could learn from the experiences of local people battling invasive plant dominance, who are consummate adaptive managers.

Fourteen years later, and now I have been working also on the Far South Coast, invited by Dr. Josh Dorrough, where we have been conducting research on African lovegrass in critically endangered Lowland Grassy Woodlands.

Just last year, we set-up a 5-year experiment to further assess the cross-trophic level impacts of African lovegrass on ecosystem function across twelve sites in the region (six paired sites—six native dominated and six African lovegrass dominated), which includes a detailed assessment of plant and invertebrate communities. We completed a very detailed sampling in 2019 prior to the fires. This project and my previous projects are being conducted in close collaboration with a network of local farmers, Far South Coast Landcare, and South East Local Land Services.

In November setting up a multi-site experiment in grassy woodland, areas with African lovegrass had high amounts of standing dry biomass. Credit: Jennifer Firn.

With the devastating fires and recent rains, African Lovegrass is recovering quickly in the Bega Valley and with the severe loss of ground vegetation. This is exactly the type of wide-scale disturbance it needs to gain an even stronger foothold in endangered Lowland Grassy Woodlands and in native pastures. Fires in Stanthorpe/Tenterfield and also on K’Gari in 2019 are also seeing the further spread of African lovegrass in 2020, along with other non-native grasses.

Anecdotally, I cannot help but guess that African lovegrass (and other non-native grasses) in these regions would have helped to fuel the intensity of recent fires. Many non-native grasses were intentionally bred in pasture improvement programs to grow fast and because of this quick growth, low palatability for some grasses when tissue starts to age, species like African lovegrass tend to hold more standing dry biomass during drought times. This availability of high amounts of standing hay during drought also has the potential to link up forested areas in agricultural landscapes that otherwise were isolated in the matrix of different land uses.

If I can honestly say I know anything for certain, from more than a decade researching African lovegrass and other invasive plants like Cenchrus ciliaris (buffel grass), it would be that a direct focus on removing the invasive plant species seldom works unless its population is very low. Often the dominance of opportunistic colonisers, like African lovegrass, is a symptom of other issues rather than a cause.

The good news from all of this, I think, is we have an opportunity to put into place wide-scale management actions to restore Themeda triandra (kangaroo grass) and other native grasses in strategic areas in the Far South Coast, Monaro, Darling Downs and on Fraser Island; thereby reducing opportunities for African lovegrass and other invasive plant impacts to take hold.

Imagine the positive impacts for ecosystems as a whole, if we could work together at the landscape level across regions to promote native grasses that are so often overlooked and undervalued.

For more information, contact Jennifer here. ¤

Read more from the March 2020 ESA Bulletin.

Banner image: Fires in 2019 on K’gari were slow burns that acted to rejuvenate ecosystems on the southern tip of the island. Some of the first species to regenerate are native and non-native grasses including African lovegrass. African lovegrass has almost certainly arrived on to K’gari from tourist vehicles or road graders being found along some inland roads in the drier are-as. The African loverass seed is tiny (<5mm in size) but germination success is high. I have even seen populations of Afri-can lovegrass on the trail walking up to Indian Head Lookout on K’gari, likely having been carted up there by animals or people’s shoes and clothing as there is no vehicle access in these areas. Credit: Jennifer Firn.