Impacts of climate change on eucalypt distributions in Australia: an examination of a recent study

Abstract

ABSTRACTA recent study examined the possible impacts of climate change on 657 Australian eucalypt species in the period to 2085 using species distribution modelling (SDM). The study predicted that ‘within the next 60 years the vast majority of species distributions (91%) across Australia will shrink in size (on average by 51%)’. The purpose of the present paper is to demonstrate some of the strengths and weaknesses of this previous study. Its main strength is that it identifies relatively hot and dry areas of species distributions that may be vulnerable under climate change. Its main weakness is that the individual analyses tend to overestimate the areas of species natural distributions. Consequently, the predicted percentage losses of species distribution areas are unreliable. To illustrate the problem the freely available Atlas of Living Australia (ALA) is used examine two contrasting species (Eucalyptus diversicolor and E. nitens) in detail, so readers will be able to apply similar methods to any eucalypt species of interest. For well-known species a more reliable assessment of likely losses of distributional area under climate change may be obtained by applying the results of the SDM analysis, but assuming that ALA occurrences within 25 km x 25 km areas are an accurate representation of present natural distributions. Using this approach the estimated loss of area of natural distribution by 2085 for both E. diversicolor and E. nitens are less than half the estimates provided by the original paper. For lesser-known species, it is concluded that an additional SDM analysis is required to provide a closer representation of species natural distributions, to which the original SDM climate change results, which attempt to capture some of the species adaptability/plasticity, could be applied.