Biodiversity Offsets: Canberra’s Ecological Prisons

Jake Adlam – u6078885

Biodiversity offsets were introduced to the ACT in the Planning and Development Act 2007, as a way of meeting environmental requirements established by the 1999 Environmental Protection and Biodiversity Conservation Act (EPBC). They have been growing in popularity in the ACT in recent years as a way of mitigating the impacts of urban development on critically endangered ecosystems such as Box Gum Grassy Woodlands (Box Woodlands) and Natural Temperate Grasslands (NTGs), and the various endangered species they support. Currently large parts of Gungahlin and the Molonglo Valley are protected and managed under this policy.

Environmental Offsets, ACT: Credit – ACT Gov

On the 19th and 20th of August I visited many of these offset sites with the ACT Parks and Conservation Service’s Environmental Offsets team. Our job, to set up survey sites designed to monitor for the presence of striped legless lizards (Delma impar), an endangered reptile species endemic to NTGs in the ACT. We spent many hours laying out large ceramic roof tiles, come spring time, the lizards make use of these warm ‘artificial refuges’ to stay hidden and raise their body temperature. Most of our time was spent removing old broken tiles from years gone by and transporting them to the tip, but in doing so we did spot many a reptilian inhabitant including three-toed skinks (Hemiergis talbingoensis) and some Boulanger’s skinks (Morethia boulengeri) as well, though sadly it was apparently to cold to be seeing any D.impar just yet.

Striped Legless Lizard (Delma impar): Credit – Bush Heritage Australia

Although it was heart-warming to see the dedication and passion of the Offsets team, and to learn from their wealth of knowledge and experience, I couldn’t help but feel disappointed at the reality of these offset sites in the ACT. Many of the sites we visited we’re heavily degraded, home to an over abundance of rabbits, stock and kangaroos, as well as a multitude of invasive flora including serrated tussock (Nassella trichotoma}, Chilean needle grass (Nassella neesiana) and various canary grasses (Phalris spp.). Although it is clear that management actions are being taken to lessen these pressures (weeding, culling, stock rotation, etc.) there are some issues that I cannot see being overcome.

Sheep surround our vehicle, Jerrabomberra West offset site

All the sites we visited appeared to me, akin to a wilderness prison, grasslands hidden behind tall fences and locked gates, isolated remnants of natural ecosystems sectioned of from the public and from each other. It seems to me that biodiversity offsets in the ACT create small, disjointed pockets of habitat, that lock in populations of endangered species, increasing the risk of genetic isolation and local extinction from stochastic events. Furthermore, tall fences keep these fledgling natural ecosystems out of site and out of mind for the ordinary Canberran, creating a distinct barrier between the city and nature. Sites near homes were plagued with dumped rubbish, a sign that locals don’t feel a sense of connection or ownership with these ecosystems. In short, our current way of selecting and managing biodiversity offsets alienates the community and isolates endangered species, a sustainable city should integrate these rare ecological communities into our everyday lives.

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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