Our research focuses on the population dynamics of plants and how they are influenced by impacts of natural disturbances and global environmental change. We are particularly interested in the interactive effects of fire, grazing and drought in grasslands and woodlands in southern Australia, and how climate change, fragmentation and shrub encroachment affect ecosystems.

Tuesday, 16 July 2013

Why grasslands need 'champions'

Because native grasslands exist as small, isolated fragments in an agricultural landscape across most of south-east Australia, they present challenges to management on lots of levels. Indeed, their small size is one of the biggest challenges, mostly because of the perception that small remnants are hard to conserve.

A native grassland on a three-chain wide roadside in western Victoria. A 'chain' is about 22m long, and was used by early surveyors to measure distances for road reserve allocations, blocks, town commons, etc. Ptilotus macrocephalus is the flowering plant you see in the foreground, surrounded by tussocks of the C4 grass Themeda triandra.
(Photo: Fiona Sutton)
Edge effects, weed invasions, small populations, isolation and inbreeding are all very real problems faced by remnant grasslands. But I've found one of the biggest challenges we face to conserve biodiversity in grasslands is to get management implemented. Consistently. This is not meant to attack the people who manage grasslands but, rather, highlight that we need to be aware that despite lots of excellent ecological research that informs management, and the fact that there are many enthusiastic, dedicated professionals and volunteers in this field, grasslands need intensive and on-going inputs to maintain their values. And the difficulty of doing this should not be under-estimated when thinking about management over multi-decadal scales.

I've just achieved one small gain for grassland conservation. In this Blog post, I want to tell you about the journey I had to take because I think there is a salient lesson to be learnt.

Truganina Cemetery is one of the jewels in the crown for grassland conservation in the Melbourne area. It might only be approx. 1.5 ha in size, but it contains large populations of at least two nationally endangered plant species (Button Wrinklewort, Spiny Rice-flower), is species-rich, and hardly has any weed invasion. The earliest gravestones date to the 1860s, and we know there are unmarked graves of early European settlers that date from even earlier times as they made their way to the goldfields of Ballarat. Because it was set aside from grazing at least 160 yrs ago, it retains a complement of native species that are missing from the surrounding grazed, species-poor grasslands. Indeed, many of the native species can only be found in places like Truganina.

Truganina Cemetery in late autumn, 2013. The centre of the cemetery is a superb example of a little grazed native grassland.
(Photo: John Morgan)

Such sites are crucial for conserving local genes of once-widespread species. And they are the place where we might collect seed to develop seed orchards, and produce plants to introduce into conservation reserves when restoration is attempted. We can't under-estimate their role: if we want to save the ecosystem, we have to save all the pieces!

To maintain the plant diversity of native grasslands, the impact of the dominant tussock grasses on smaller, less competitive inter-tussock species need to be moderated. This has been done by burning in many areas, although it is feasible that slashing (and removal of the cut material) could achieve the same aims (as might stock grazing in areas where grazing has been part of the recent history of  the grassland). I've written about this in previous posts, and it's been a central idea in the ecological literature since John Stuwe & Bob Parson's seminal paper on grassland floristics and management effects (see Australian Journal of Ecology 2, 467-476).

At Truganina, the last management burn was approx. 10 yrs ago (in 2002, although the record keeping is hazy on this). Since that time, there has been a long and protracted drought, and this seems to have slowed down the rate of biomass accumulation, such that the necessity to burn has been quite low. It's been interesting to see how grassland productivity at Truganina is tied to annual rainfall (as it is in prairies). In drought years, I'd suggest there has been a decline in grass biomass as litter decay exceeds litter build-up via new tiller growth. But, with the breaking of the drought in 2010-11, productivity increased dramatically. By 2012, it was clear that the grassland needed disturbance (to the vegetation) to open up inter-tussock spaces and if this did not occur, it was probable (i.e. highly likely) that the biodiversity values would be compromised.

No-one disagreed with this assessment. But to get Truganina burnt, our preferred option, took a little longer than might have been hoped and hints that to achieve management outcomes (sometimes) requires persistence and dogged determination.

Bob Parsons and I (and others) wrote to the secretary for the  Minister for Environment in the state of Victoria in December 2012, talking about the need to burn important grassland sites around Melbourne (not Truganina specifically) in autumn 2013 because of the dramatic build-up of grass biomass. We got a letter back from the Regional Director (11th January 2013), thanking us for raising the issue, and that they'd look into this.

On the 29th January 2013, we raised the need for burning at Truganina.

What proceeded to occur was that we had a further 23 emails/phone calls/interactions with the people needed to undertake the burn. These interactions highlighted the need to (a) follow-up on requests, (b) find out the status of proposed actions and (c) nag when things weren't moving in a manner we thought satisfactory.

I want to stress that I'm not having a go at the wonderful individuals that have helped us along the way. Rather, it highlights that managing grasslands in an urban context is difficult! Government agencies, OH&S requirements, contractor availability, the weather and public liability all came into the equation at some stage.

On the 5th June 2013, Truganina was burnt. As the photos show, the fire was low intensity and patchy. Crucially, it occurred before re-sprouting and seedling emergence had occurred, and I'm hoping we will see a flush of growth, flowering and regeneration in the coming year. This is an excellent outcome for this tiny remnant and ensures that the values we cherish so much are likely to hold on for another decade or so.
Truganina grassland - burning for the first time in a decade or so.

Truganina grassland, a few days after burning in June 2013
(Photo: John Morgan)

This experience has taught me a lesson: the value of championing a site. If you have a local grassland that you want preserved and managed well, then agitate for it to happen. I'm pretty sure that with local inputs into local remnants, better outcomes will ultimately be achieved for the protection of those remnants. By championing small sites, we ensure that they don't fall through the management cracks.