Climatic range sizes of Eucalyptus species in relation to future climate change

We present data on the climatic ranges of 819 species of Eucalyptus L'Herit in Australia, in terms of mean annual temperature and rainfall. 53% of species currently have ranges spanning less than 3 degrees C of mean annual temperature, with 41% having a range of less than 2 degrees C, and 25% with less than 1 degrees C. 23% of species have ranges of mean annual rainfall that span less than 20% variation. Unless current projections greatly overestimate future climate change in Australia, within the next few decades many eucalypt species will have their entire present day populations exposed to temperatures and rainfalls under which no individuals currently exist. While we recognize that the actual climatic tolerances of many species are wider than the climatic envelope they currently occupy, the data indicate that if even a moderate proportion of present day boundaries actually reflect thermal or rainfall tolerances, substantial changes in the tree flora of Australia may be expected.