Mature Native Trees: Pillars of Biodiversity
“We literally cannot live without trees” Darren Le Roux, Environmental Project Officer, ACT Parks and Conservation Service
The nomination of “Loss of Native Hollow-bearing Trees”, as a threatening process under the Nature Conservation ACT 2014, was discussed during our February 2017 Environment Exchange forum. Community groups, local and federal government and interested members of the public came together to discuss the value of mature trees and the potential avenues for guaranteeing their protection.
Mature trees are pillars of biodiversity in the ecosystem. They provide habitat for wildlife, nurseries for seeds to grow and facilitate vital soil processes. Darren le Roux, Environmental Project Officer, ACT Parks and Conservation Service, discussed the importance of not underestimating the value of some of the earth’s “longest lived organisms”.
Darren revealed that trees take 100-300 years to form hollows, and described of some of the wide range of wildlife that utilise them for shelter and breeding. In the ACT, many of these species are currently listed as threatened, including the Swift Parrot, the Superb Parrot, the Brown Treecreeper and the Glossy Black Cockatoo. Unfortunately, the outlook for these species is bleak.
Modelling suggests that we could lose these keystone structures within 120 years if current practices continue. Whilst efforts are being made to plant thousands of trees across the ACT, there is an unavoidable time lag while we wait for the trees to mature. Darren and his team are undertaking a revolutionary experiment in an effort to bridge this gap.
The ACT Parks and Conservation Service has salvaged several mature trees doomed for removal and relocated them to Barrer Hill in Molonglo in an attempt to provide some of the ecosystem features only found in mature trees. Within minutes of installing the dead trees, they were receiving visits from the local wildlife, and over time the hollows began to see use. Darren was optimistic about the initial success of the experiment and hoped to see it expand to other habitat types and jurisdictions in the future.
“Dead trees, they still have a lot of life to give” said Darren le Roux, “It’s never going to be a real tree…but the reality is we’re losing them so quickly.”
Sarah Sharp, vegetation ecologist from Friends of Grasslands, warned of focussing too heavily on specific individual values such as hollows. She reminded the group that mature trees are embedded in their ecological communities, many of which, such as Box Gum Grassy Woodland, are threatened in their own right. Sarah also highlighted the vital nature of these trees, and their communities, for human well-being including cultural values, mental health and ecosystems services such as clean air and water.
Tree removal, both on an individual and a landscape scale, is a very real threat to these incalculable values. Mature trees are routinely removed for greenfields development and those that are retained are almost unavoidably declared unsafe within the ensuing years. This compounds more indirect threats such as nearby urban areas and climate change, and even natural threats such as fire and old age.
“It’s just happening” said Sarah Sharp, “they’re getting old and falling over.”
Geoff Butler, volunteer Weeds Officer with the Conservation Council ACT Region, described a previous attempt by community groups to better protect mature trees. They were advised that the trees were adequately protected under existing legislation. After a series of tragic recent tree losses within the ACT, Friends of Grasslands, Canberra Ornithologists Group, the Conservation Council, Field Naturalists Association of Canberra and the Australian Native Plants Society, made a joint submission to the ACT Scientific Committee, requesting that they list “Loss of Native Hollow-bearing Trees”, as a threatening process under the Nature Conservation ACT 2014.
Points raised at the forum included whether campaigns to protect mature trees could be strengthened through an estimation of their economic values and a consideration of their value to risk management, particularly in the context of impending climate change. The Commissioner for Sustainability and Environment is currently considering natural accounting and that might support the case for mature tree protection. However, there was also concern that placing an economic value on trees would undermine their intrinsic and incalculable values and enable developers to “buy-off” their loss.
It is essential that we protect mature trees and the values they possess. We must ensure that these pillars of biodiversity have a continued presence in the landscape: through the prevention of further loss; the planting of new trees and enabling of regeneration, and the encouragement of innovation in bridging the existing gaps.
Visit our publications page for links to short videos and presentation slides from the “Mature Trees: Pillars of Biodiversity” Environment Exchange, March 2017.