Identifying performance indicators of the effects of forest management on ground-active arthropod biodiversity using hierarchical partitioning and partial canonical correspondence analysis

Abstract

Biodiversity conservation in Australian native hardwood production forest is a central aim of sustainable forest management. However, the effects of timber extraction and fuel-reduction burning on the biodiversity of forest invertebrates are poorly understood. In this study, we use hierarchical partitioning and partial canonical correspondence analysis to examine the independent effects of these management practices on the richness and composition of ground-active ant and beetle assemblages. The study makes use of survey data from two types of production forest widespread in north-east New South Wales, New England Blackbutt ( Eucalyptus campanulata, R. Baker and H.G. Smith) and Messmate/Forest Ribbon Gum ( E. obliqua, L’Hér and E. nobilis, L. Johnson and K. Hill). Pitfall-trapped ants, and beetles from the families Carabidae, Scarabaeidae and Pselaphidae, were sorted to morphospecies and these survey data, together with habitat data, were used to explore two questions: (1) how much variation in the richness and composition of the arthropod assemblages at survey sites could be accounted for (independently) by logging and fire history? and (2) were other habitat variables better able to (independently) account for variation in arthropod richness and composition? Answers to these questions were used to identify potential performance indicators of the effects of forest management practices on ground-active arthropod biodiversity. Our analyses found that in New England Blackbutt forest sites, where selective logging was at low intensity, logging history explained little variation in arthropod richness or composition. By contrast, a strong influence of fire history and correlated habitat variables was evident. Fire history also explained significant variation in Messmate/Forest Ribbon Gum forest, but in this forest type, where logging intensity was higher, the influence of logging history was also apparent. This study finds support for the use of measures of ant richness, percent cover of sub-canopy (5–15 m above ground level) and ground-layer characteristics (litter depth, % cover of litter and bare ground) as performance indicators, because these attributes are relatively easy to measure, are affected by forest management, and are indicative of the effects of forest management on ground-active arthropod biodiversity.