By Joern Fischer
Today I’d like to point you to a new publication that just came out in Conservation Letters. It’s a study led by Karen Stagoll, who I’ve had the pleasure to work with when I was still in Canberra. Karen helped me measure trees several years ago. And I guess she found this so much fun that she decided to measure some of her own!
And so she did. Lots of them. In fact, over 3000 trees, all over Australia’s capital city, Canberra. Canberra is known as the ‘bush capital’ because throughout the city there’s a lot of native vegetation — in nature reserves, but also in urban parks. The setting is far from pristine — but it’s also far from the urban concrete jungle that characterises so many other large cities around the world.
In her work, Karen found that urban trees make a major difference to bird diversity. Especially the large trees appear disproportionately important, considering their small footprint in the landscape. One problem in Australia is that old, large eucalypt trees have a tendency to occasionally drop some branches, and sometimes those are pretty large. In public places like parks, this can be perceived as a potential danger, for example to the children who might play in these parks.
While this is a reasonable concern for public health, Karen’s work has shown that it’s important to not just think of the ‘danger’ coming from these trees, but also think about their value for making the ‘bush capital’ biodiverse and nice to live in. Large trees attract many birds, and so strategies must be found to maintain (and perpetuate) such large trees, rather than risk their decline, or actively remove them. Can this be reconciled with public safety? Clearly, yes. For example, shrubs could be planted underneath some of the largest, oldest ‘high risk’ trees, so that people won’t be able to sit right underneath branches that are a potential danger.
People love their birds, and especially in Canberra, incredibly beautiful birds are currently a common sight. Want to see those birds in the future still? — Then think big trees.