Biodiversity monitoring informs forest management in south-west Western Australia: Ten-year findings of Forestcheck

Abstract

Long-term monitoring is an important element of ecologically sustainable forest management and provides the foundation for adaptive management under conditions of uncertainty and change. Management of the jarrah (Eucalyptus marginata) forest in south-west Western Australia is supported by an integrated monitoring program (Forestcheck) established to inform forest managers about trends in key elements of biodiversity associated with management activities. Forty-eight monitoring grids were established across four jarrah forest ecosystems following timber harvesting and silvicultural treatment, as well as in nearby forest that was unharvested or harvested >40 years previously. Biota monitored includes terrestrial vertebrates (mammals, birds, reptiles, and amphibians), vascular plants, epigeous macrofungi, cryptogams (lichens, mosses, and liverworts) and macro-invertebrates. Initial findings from a first round of monitoring between 2001 and 2006 were published previously. Here we report on a second round of monitoring undertaken between 2007 and 2012 and compare findings with the previous round for taxonomic richness, community structure, and response to silvicultural treatment and time since fire. We tested two hypotheses for each of the groups studied: (1) that silvicultural treatment or (2) time since fire had no effect on (a) richness or (b) assemblage composition.A total of 3787 taxa were recorded. Dominant factors influencing total species richness and composition were forest ecosystem type, time of monitoring, time since harvesting and time since fire. Silvicultural treatment had no significant effect on mean richness of invertebrates, macrofungi, vascular plants and birds for either monitoring period but cryptogam richness was higher in unharvested forest and species richness of terrestrial vertebrate fauna was higher in harvested forest. Time since harvest had a significant influence on all species assemblages except terrestrial vertebrates but over time effects were ameliorated other than for cryptogams and birds. Time since fire had no effect on taxonomic richness for any of the groups examined, but significant differences in assemblage composition were detected between three categories of time since fire for all the groups except terrestrial vertebrates.Knowledge of the distribution of individual organisms and the composition of taxon assemblages in jarrah forest has been significantly improved as a result of monitoring, particularly for invertebrates, macrofungi and cryptogams. Some taxa across all groups were only recorded in forest subject to specific management including unharvested reference forest and forest subject to different intensities of timber harvesting, demonstrating that disturbance associated with timber harvesting and post-harvest burning can create conditions favourable for some organisms that are otherwise encountered rarely in mature forest.These results demonstrate the critical role of well-designed, systematic and multi-taxon ecological monitoring programs for evaluating biological responses to often contentious forest management practices.