Monitoring Tree Growth in the Scottsdale Reserve – A potential African Lovegrass management program.

Scottsdale Reserve is located 4km North of Bredbo in NSW and is a 1328 Ha Nature Reserve owned in partnership by Greening Australia and Bush Heritage Australia Reserves & Partnerships – https://www.google.com/maps/d/viewer?mid=1o5Z89ln5sT5pQw_ioBOrsU2YmTY&usp=sharing.

Purchased as a conservation property it boasts large areas of box gum grassy woodlands and temperate grasslands, currently listed as endangered under the Environmental Protection and Biodiversity Conservation (EPBC) Act 1999, as well as Tablelands frost hollow grassy woodlands and southern tablelands natural temperate grassland. The property also hosts a remnant of the last ice age, known as the Silver-leafed Mountain Gum (Eucalyptus pulverulenta) which is only known to exist in ten populations throughout Australia.

Figure 1 – Eucalyptus pulverulenta (photo courtesy of Daves Garden http://davesgarden.com/guides/pf/showimage/66793/)

Figure 2 – The Peregrine Falcon is a common sighting at Scottsdale Reserve (Photo courtesy of Greening Australia)

Rosenberg’s Monitor (Varanus rosenbergi), the Speckled Warbler (Pyrrholaemus sagittatus) , the Peregrine Falcon (Falco peregrinus macropus), and the Brown Treecreeper (Climacteris picumnus) are also known to frequent the area, while the river system that passes through the Northern most point of the property is home to native fish, Platypus (Ornithorhynchus anatinus) and the source of more even more conservation action through the Upper Murrumbidgee Demonstration Reach (UMDR) project which looks at Carp control and Willow reduction to improve flow and quality in the Murrumbidgee River while enhancing the environment for the Macquarie Perch (Macquaria australasica) and Trout Cod (Maccullochella macquariensis).

About 300 Ha of the property has been grazed, cleared, cropped and sown since the 1870s’ and is now home to the noxious weed known as African lovegrass (Eragrostis curvula). E. curvula was introduced into Australia before the 1900s’ and is now a significant weed across much of Australia’s agricultural landscape. Several experimental trials are underway on the property to look at ways of managing the weed.

Figure 3 – A 100m transect of tree plantings being monitored for growth.

One feature being monitored at Scottsdale, and the source of our reason for being there, is to monitor trees planted in an attempt to restore the native box gum grassy woodland. It is believed that through those plantings there is a capability to assuage the growth of the lovegrass through competition with native flora, a theory derived from the grass’s notable absence around the base of large paddock trees.

Figure 4 – A stand of paddock trees with a notable absence of E. curvula.

Around 6 km of direct seeded tree lines have been planted across the property with around 40 monitoring transects identified. These transects have been marked out using pegs to identify each end of the transect and labels to identify the transect by number. Dr David Freudenberger, Associate Professor and lecturer from the ANU has been involved in the monitoring activities since the transects were marked out.

Figure 5 – Pegs and labels used to identify the monitoring transects

The tools provided included a 100m tape, to measure the point along the transect that the tree is planted, and a set of calipers, used to measure the basal diameter of each tree along the transect.

Figure 6 – The tools required to perform the measurements

With our tools at the ready and Hi-vis vests on we traversed 25 of the transects and collected presence and basal diameter measurements from them as well as photo points. The data collected from these measurements is put into an Excel spreadsheet and the photos are arranged as a time series so that the change through time can be monitored.

Figure 7 – Some of the transects monitored since 2013

The real eye-opener to the impact of the African Lovegrass is when you have to spend all day walking through it. It is a tough, drought resistant grass and requires very little nutrient to thrive. Even though it is quite unpalatable for livestock, it is very highly structured and therefore offers good habitat for birds and lizards, in particular the stripped legless lizard (Delma impar) that has recently been introduced to the Scottsdale reserve as a trial of forced immigration to the area. Along with that the grass offers excellent protection to the soil underneath, through the rain-splash protection offered by the above ground biomass and also erosion protection given by the large root structure that the plant puts down into the soil around it.

Figure 8 – A heavy infestation of E. curvula (Photograph by Greg Ried)

The tree plantings are still quite young and potentially very many years away from revealing how great the impact will be to the existence of the love grass. Even if the trees are successful in out-competing the grass it doesn’t really present a solution to the average farmer whose property is overrun by the grass. African Lovegrass is very nearly unstoppable once it invades a landscape and the only method of protection available to land owners is achieved by protecting unaffected areas from infestation of the weed (DPI, 2013).

While Scottsdale reserve, and many other conservation properties, are attempting to unravel the complexities of restoring their local heavily grazed or cropped areas to their former box gum grassy woodlands state, many other connectivity programs are being developed to join the landscape across larger scales and Scottsdale is an important piece in the connectivity puzzle. A project known as the Kosciuszko 2 Coast, or the K2C, project has been established to stimulate the movement of biodiversity from the coast to the highlands by increasing connectivity through green corridors.

It is truly rewarding to be involved with an organisation like Bush Heritage Australia, knowing the difference they are attempting to make on both the local and national scale in improving connectivity so that biodiversity can flourish in today’s landscapes.

U5562640

AWI & MLA, African Lovegrass: 3D weed management.

Bush Heritage Australia, 2016, Annual Report 2015-2016 – Bush Heritage Australia, Available at: http://www.bushheritage.org.au/about/about-us/annual-reports.

Bush Heritage Australia, Bush Heritage Australia Reserves & Partnerships. Available at: https://www.google.com/maps/d/u/0/viewer?ll=-35.90122573%2C149.12869543&z=11&mid=1o5Z89ln5sT5pQw_ioBOrsU2YmTY.

DPI, 2013, African Lovegrass management. Available at: http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0019/320158/African-lovegrass-management-web.pdf.