How much native habitat is enough?
The question for farm and landscape planning is: ‘How much intensive production can take place without excluding most native species from the landscape?’ Roughly speaking, if any land use that largely excludes native biodiversity (eg, crops, plantations, fertilised pastures) covers less than one-third of the landscape, it is unlikely to lead to the disappearance of native plants and animals. Obviously the activities in the other two- thirds of the landscape are important in determining exactly which species thrive and which do not. Based on a review of the evidence, scientists have developed suggestions for the relative balance of different land uses across a landscape, known as the 10:20:40:30 guidelines. This proposes a suggested proportion of landscape use: 10 = over 10% under native vegetation and managed for conservation; 20 = over 20% under native vegetation but used for production purposes; 40= 40% used for modertate intensity production; and 30 = 30% or less given over to high-intensity production.
Page 115 in Biodiversity: Science and Solutions for Australia, the new ebook from CSIRO; available free at http://www.csiro.au/ biodiversitybook