Insight into the repercussions of past environmental irresponsibilities

Jake Bradley

Dates of Conservation Volunteering Australia

6/10/16 – Scottsdale tree planting

10/10/16 – Tidbinbilla Weed Removal

After prolonged agricultural in rural settings post-European settlement, reverting a landscape back to its ‘original’ function is problematic. The ‘best practise’ and ‘method’ ideally follows one of adaptive management or more simply trial and error. The folks at the green army and Conservation Volunteers Australia may understand this the best. Each habitat is different, and while one tactic may reform a particular habitat it may not for another. The current ‘on-trend’ restoration strategy employed by Greening Australia is called Whole of Paddock Restoration or WOPR. WOPR aims at restoring a ‘site’ to its native species composition through the direct seeding of shrubs in a number of widely space seeding lines 30-50m apart. Vegetation within a row is spaced around 7m apart so that competition between seeds is minimal. Seeds are maintained for a period of 5 years, at which time they are deemed to be sufficiently established that they no longer require care. Benefits for nature conservation that the WOPR process has for the environment are all to do with the artificial reintroduction of native tree species. These include;

  • Native bird abundance increase
  • Stepping stones for mobile species between remnant patches
  • Regeneration of remnant vegetation
  • Increased carbon sequestration
  • Restoration of natural biological cycles in the area.
  • The increased ability to provide habitat for potentially vulnerable Australian species (Greening Australia, 2008)
wopr

Figure 1 – WOPR lines that have just been reseeded by the Green Army (Green Army, 2008)

wopr2

Figure 2 – How WOPR looks 12 years after the seeding process (Green Army, 2008)

I recently visited a Green Army restoration site at Scottsdale reserve (operated by Bush Heritage Australia, you can find the Scottsdale page here). Scottsdale occupies 1,328 hectares of varying-in-quality Box-Gum Woodland. 300 ha of the area has had prolonged grazing, sowing, and clearing activity. The Yellow-Box Red-Gum Grassy Woodland (previously mentioned as Box-Gum) is a critically endangered ecological community under Australian legislation (EPBC Act 1999).  Scottsdale is employing the WOPR technique to restore that 300 ha of grassland.

Scottsdale and surrounds have to manage for wild deer, goats, rabbits and native herbivores that benefit from having freshly planted saplings in the vicinity. Managing for animal’s impacts and abundance is always a contentious issue for conservationists. For companies like Bush Heritage, donations and funding from non-government private sources can be the difference in effective rehabilitation efforts. Activities like Kangaroo culling can pull the support of a number of interested parties. Strategies that are allowed have to be conducted in a way that does not impact native species, who occupy similar niches in the habitat and surrounds.

One thing that troubled me whilst I was out working at Scottsdale was the presence of the dreaded African Lovegrass (Eragrostis curvula), which I was told covered 90% of the area we were working in. All this effort was going into establishing a native overstory but the exotic understory was being ignored.

The introduction of exotic grasses into Australia with agriculture has changed the chemical make-up of soil across much of Australia. Native grasses thrive in nutrient deprived soils, but because of a long history of fertilizer in the soils in Scottsdale, exotic grasses that love nitrogen rich soils took over.

In order to facilitate an environment where native ground cover can effectively compete with exotic, the soil has to be abiotic (reduced nitrogen and phosphorus). A new method that could achieve this is called ‘scalping’. Scalping involves removing the top 10-15 cm of soil from a landscape in the hope to remove the nutrient-rich layer that these weeds thrive off. Scalping works best with some measure of soil disturbance (Cole et al. 2004) applied prior to the excavation.

Linking these methods used for rehabilitation and native habitats is difficult. WOPR, as seen in figure 2 does not resemble a natural distribution on native structures. The spaces within planting lines could in the future alter how native ecosystems are structured. WOPR is usually aimed at balancing habitat restoration and livestock, and so its use in the Scottsdale reserve seems arbitrary. In places where livestock are not present to need spaces in-between plantations to forage, why not attempt to create a more natural spatial assortment of species?

With a national shift from these modified agricultural areas to a highbred native-agriculture layout or even to just a pure conservation focus, comes many unforeseen and interlinked problems. It is a learning process for all parties, and with time it will become cheaper and more effective. However, time brings perspective with matters of conservation. We look back 20 years ago and wonder why we converted these natural landscapes the way we did. I just hope we don’t look back tomorrow and wonder why we are doing what we did today.

References

Cole I. Lunt I, D. Koen T. 2004. Effects of soil disturbance, weed control and mulch treatments on the establishment of Themeda triandra (Poaceae) in a degraded white box (Eucalyptus albens) woodland in central western New South Wales. Aust. J. Bot.

Greening Australia Capital Region,. 2008. Whole of Paddock Rehabilitation.  Eds. Fifield G, Streatfield S, Vanzella B.

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About Biodiversity Conservation Blog

I am an Associate Professor at The Australian National University and convene a (very awesome) course called Biodiversity Conservation. Myself and students in the course contribute to this blog.
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One Response to Insight into the repercussions of past environmental irresponsibilities

  1. Thanks Jake. It’s good to hear what is happening at Scottsdale. Phil

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