Geoscience Reference
In-Depth Information
4
Changes to Australian terrestrial
biodiversity
Lesley Hughes
Introduction
Australia is considered one of the most megadiverse countries in the world, being
home to 7-10 per cent of the world's species (Mittermeier, Gil and Mittermeier,
2007). The continent's biodiversity is already subject to multiple threats, and
rapid anthropogenic climate change will add to and interact with these existing
stresses. The challenges for predicting the future of Australia's terrestrial plants
and animals are immense. We have a far-from-adequate understanding of the
multiple factors determining the distribution and dynamics of even single
populations or species, let alone whole communities and ecosystems. Further,
biological systems tend to respond to environmental drivers in a non-linear
fashion, and the likelihood of sudden ecological surprises and rapid transforma-
tions will increase.
But despite the challenges, we must use whatever means we have to assess
future risks, to provide a basis for adaptation planning. In this chapter I
first discuss how the environmental and biogeographic context under which
Australia's flora and fauna evolved offers us general guidance for predicting its
future vulnerability and its potential to adapt. I then explore the likely conse-
quences for species and ecosystems of future rapid climatic change, the potential
for our biodiversity to adapt and the ultimate consequences of future loss.
Environmental and biogeographic context
Australia's rich terrestrial biodiversity has been shaped by the unique combi-
nation of its highly variable climate, its long period of isolation from other
continents, its highly weathered and infertile soils, its flat topography and by the
long history of human occupation (Orians and Milewski, 2007). These factors
also offer general clues to the likely responses of species to current and future
climatic change, by affecting species' exposure to stress and by determining their
capacity to adapt.
Australia broke free from the super-continent of Gondwana approximately
45 million years ago. Its current biota is a combination of relict Gondwanan
elements shared with South America and Africa, combined with later arrivals
