Maximising biodiversity in plantation forests: Insights from long-term changes in clearfell-sensitive beetles in a Pinus radiata plantation

Forest management practices can be detrimental to the long-term persistence of native species in exotic tree plantations. Knowledge of population recovery times post-harvest and dispersal capabilities of native species are critical to the development of spatially-explicit stand management plans that maximise biodiversity opportunities at a landscape scale. To quantify post-harvest recovery patterns we studied the relative capture rates of seven beetle species known to be sensitive to clearfell harvesting. A chronosequence sampling approach was implemented, with sampling along 580-m long edge gradients from the interior of multiple replicated mature stands of 26 years of age into adjacent regenerating stands of 1, 2, 4, 8, 16, and 26 years of age. Beetle capture rates were strongly affected by clearfell harvesting, however, population recovery of all species was possible within the timeframe of a single rotation when adjacent mature or closed-canopy stands were present. Recovery time was closely linked to the development of a closed canopy (8–16 years), with distinct differences in the responses of individual beetle taxa reflecting habitat preferences for open or closed forest. Such time-to-recovery analyses provide insights into temporal aspects of insect–plant–habitat interactions and can give forest managers better guidelines to maximise biodiversity opportunities at the landscape scale. Although the time to canopy closure provides a useful proxy for recolonisation by forest species, specific timeframes will vary biogeographically and are dependent on the original native vegetation context and species assemblages present. In addition, forest managers and public advocacy groups will need to make qualitative decisions about what biodiversity attributes should be conserved.