Models of the distribution and abundance of ground-dwelling mammals in the eucalypt forests of south-eastern New South Wales

Abstract

We examined the relationship between ground-dwelling mammals and the environment within 500 000 ha of eucalypt forest in south-eastern New South Wales. Ground-dwelling mammals were surveyed at 368 sites in 13 areas in relation to four habitat variables/factors, seven environmental variables, and two derived variables (‘disturbance’ and ‘prey abundance’). Habitat variables are vegetative variables such as eucalypt community and forest structure that may be altered by man (e.g. logging) or natural disturbances (e.g. wildfire). Environmental variables are climatic or topographic variables such as rainfall or lithology that cannot be altered by man or natural disturbances.

Statistical models are presented of the distribution and abundance of ground-dwelling mammals in temperate eucalypt forests. From studies of the prediction of eucalypt species from environmental variables and the distribution of arboreal marsupials it has been possible previously to map the predicted density of arboreal marsupials for a large area of south-eastern New South Wales. It would be difficult to do the same for the ground-dwelling mammals because of the importance of structural variables and the influence of disturbance on structure. However, there appears to be a positive relationship between the abundance of some ground-dwelling mammals and environmental variables such as the lithology nutrient rating.

Many past studies of fauna have stratified sampling on broad climatic and terrain variables and not included an adequate proportion of the structural variation, which may remain concealed as a large part of the unexplained variation. This may be the single most important problem facing reliable modelling and prediction of patterns of biodiversity in eucalypt forests.