Edgbaston Reserve reveals its secrets

Bush Heritage ecologist Paul Foreman reveals the remarkable biodiversity at Edgbaston Reserve in Queensland

It's easy to think that we know everything there is to know about the world. Each country has been mapped, every ‘lost tribe' discovered. And yet you often hear quotes like this one, from the Convention on Biological Diversity: 'Globally, around 1.75 million species have been described and formally named to date, and there are good grounds for believing that several million more species exist but remain undiscovered and undescribed' [1].

While it is true that most unknown species are insects or deep sea marine organisms, many people will be surprised to learn that a lot of terrestrial plants remain undiscovered (estimated at over 10 per cent or 30 000 species). And even though botanists have been poring over the continent since the era of Joseph Banks and Charles Darwin, it is still possible to find completely new things today – usually in remote places with unique or highly restricted environments.

The spectacular 1994 discovery of the Wollemi pine (Wollemia nobilis) [2] – a large prehistoric tree only 150 km from Sydney – is a memorable example. And, excitingly, Bush Heritage's newest reserve in central Queensland, Edgbaston, is also a case in point.

What might be perceived by most as ‘just another cow-paddock' or even a ‘terrible place' (as quoted by a local grazier in our Spring 2008 newsletter), is in fact a biological hotspot that continues to surprise with new discoveries. By now many would be aware of Edgbaston's unique, critically endangered fish, the redfin blue-eye, which was only discovered in 1990. However, the story of Edgbaston's unique plants is less well known and understood. 

In June this year, a team from Bush Heritage collected no fewer than three new plants from the reserve – all saltbushes that are endemic to the saline scalds that fringe the property's natural springs. One notable example is a delicate saltbush with distinctive and bizarre ‘antler-like' fruits. This saltbush grows only a few hundred metres from a spring on a low, saline white-sand ridge covered in porcupine spinifex (Triodia longiceps).

These new discoveries at Edgbaston mean there are now no fewer than 15 plants that have been described only very recently or still wait for a name to be assigned (see Table 1 below). Some interesting examples include: a scrambling pigface with broad, flat leaves (Figure 1), an apparently long-lived ‘woody' species of ‘Beauty-heads' (daisy family) (Figure 2) and a giant pipewort (up to 50 cm tall) growing in springs shaded under tea-tree thickets (Figure 3). All of these species are either endemic to Edgbaston or to just one or two other nearby locations with similar ecosystems. Amazingly, it is likely there are still more species to be found. 

From left:

Figure 1. A scrambling pigface with broad, flat leaves; Gunniopsis spp. (Edgbaston RJ Fensham 5094).

Figure 2. An apparently long-lived ‘woody' species of ‘beauty-heads' (daisy family), Calocephalus spp.

So why is Edgbaston so biologically rich and unique? The answer lies squarely with the permanent artesian springs scattered across the Pelican Creek/Lake Mueller complex in the reserve's east. These springs discharge from thin sandstone aquifers that recharge in the surrounding desert uplands to the north and east (Figure 5). These discharge points are often in the lowest parts of the landscape and can be separated by tens to hundreds of kilometres of unwatered land. It is thought that the resulting isolation over very long time periods drives the evolution of new species that are uniquely adapted to specific springs environments. The surprisingly high assemblages of unique organisms at Edgbaston suggests this spring complex has been relatively stable and effectively isolated for longer than most, but no one really knows for sure.

From left:

Figure 3. Eriocaulon giganticum, only recognised and described as recently as 2007 [4].

Figure 4. The distinctive ‘antler-like' fruits of Atriplex spp. (Edgbaston), first collected in June 2009 along with two other new copper burrs (Sclerolaena spp.) (Edgbaston).

In a recent seminal paper on the redfin blue-eye [3], Edgbaston was touted as ‘the most significant springs for biodiversity conservation in the entire [Great Artesian Basin]'. The more we get to know this reserve, the more we can see why!

Figure 5. Generalised operation of an artesian basin. Source: Great Artesian Coordinating Committee, www.gabcc.org.au.

Table 1. Edgbaston plants that have been described only very recently or still wait for a name to be assigned.

E, endangered nationally – Environment Protection and Biodiversity Conservation Act (Comm)
e, endangered in Queensland – Nature Conservation Act
r, rare in Queensland – Nature Conservation Act
*provisional conservation status only
Undec,  new species yet to be formally described or named

[1] www.cbd.int.

[2] www.rbgsyd.nsw.gov.au/science/wollemi_pine.

[3] R Fairfax, R Fensham, R Wager, S Brooks, A Webb and P Unmack, ‘Recovery of the red-finned blue-eye: an endangered fish from springs of the Great Artesian Basin', Wildlife Research, 2007, 34, 156-66.

[4] Richard J-P Davies, Andrew I Craigie, Duncan A Mackay, Molly A Whalen, Judy P-E Cheong and Gregory J Leach, ‘Resolution of the taxonomy of Eriocaulon (Eriocaulaceae) taxa endemic to Australian mound springs, using morphometrics and AFLP markers', Australian Systematic Botany, 2007, 20, 428-47.

PHOTOS: Paul Foreman