Macquarie University researchers from the Which Plant Where project have created the first comprehensive account of the world’s urban tree flora, and some of their findings are surprising.
They sifted through 12 million tree planting records, collected by local governments in almost 500 cities and towns globally, and published in the scientific literature. At the end of this massive exercise they were able to record an impressive diversity of tree species planted in urban green spaces. The results have been published in Global Ecology and Biogeography.
Urban spaces make up only 2 per cent of Earth’s land mass – despite what our perceptions might tell us. In their survey of just a fraction of these urban areas, the researchers identified 4734 tree species – about 8 per cent of the world’s known tree species. Extrapolating from this sample to all urban areas, they estimate that cities and towns might hold as much as one-sixth of global tree diversity.