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Kangaroos necessary for health of grasslands and grassy woodland reserves

MY INTEREST, since retirement in 2000, has been identifying and monitoring native vegetation found in the south side reserves of the ACT in particular Farrer Ridge which is close to my house. I have been walking regularly there for the past 40 years. Since 2003, I have recorded 180 species of native plants and trees on Farrer Ridge. I have pictorially recorded most of these species and made both general and detailed observations of rare species linked to monthly rainfall patterns.

In October 2008, I wrote to [then Commissioner for the Environment] and provided pictorial details of the different outcomes regarding biodiversity versus biomass of two grassy woodlands. One with Kangaroos presence (Farrer Ridge) compared to one that had no presence (Athllon Drive). Athllon Drive grassland mainly comprised matted Themeda grass and very few forbs and lilies whilst Farrer Ridge comprised a large number of common forbs, lilies and orchids in combination with grasses.

The Athllon grassland displayed characteristics of Themeda in decline due to the absence of disturbance. The matted dead grass inhibits not only the grass flowering but also smothers the smaller plants.  

LEFT: Athllon Drive Oct 2008.  RIGHT: Farrer Ridge Oct 2008. Credit Julie Lindner.

In late 2012 (or early 2013), the Athllon Drive grassland was completely mown. It had been left untouched for several years but had in the past been regularly mown. Over the next few months many of the forbs and lilies that originally inhabited that grassland returned. 

High native plant diversity with kangaroos present; cull weeds rather than kangaroos?

With kangaroos present, Farrer Ridge has constantly maintained a high diversity of plants. A recent survey conducted by Conservation Planning and Research of ACT Government recorded 10 rare species at 28 locations. I have recorded and monitored 12 different terrestrial orchid species that flower most years (mainly dependant on rainfall). There remains an abundance of delicate lilies including Caesia calliantha (Blue grass lily). 

Some species have declined over the13-year period but as a result of poor management practice rather than kangaroos. Donkey orchids were destroyed in one part of Farrer Ridge by the constant digging of mountain bike trails that was allowed to continue unchecked. A large tract of Calotis anthemoides was poisoned by supervised spraying and Swainsona sericea completely eradicated by a contractor spraying weeds. I have not observed any decline in species due to the presence of kangaroos.        

If the resources in terms of manpower, effort and money used to cull kangaroos over the last three-year period had been diverted to control the weeds listed in the Pest Plants and Animals Declaration 2008 (No1) (ACT) as ‘must be suppressed’ or ‘must be contained’, most of the reserves would be in better condition than they presently are.  

Weeds pose a far greater threat to the biodiversity and preservation of the endangered Red Gum/Yellow Box grassy woodlands than the grazing of large numbers of kangaroos. Presently weeds are engulfing all the grassy woodlands areas of the ACT and it appears nothing is being done to contain them.   

— Julie Lindner, naturalist, testimony
Farrer, ACT

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