A decade of change in the saproxylic beetle fauna of eucalypt logs in the Warra long-term log-decay experiment, Tasmania. 2. Log-size effects, succession, and the functional significance of rare species
Grove, SJ and Forster, L, A decade of change in the saproxylic beetle fauna of eucalypt logs in the Warra long-term log-decay experiment, Tasmania. 2. Log-size effects, succession, and the functional significance of rare species, Biodiversity and Conservation, 20, (10) pp. 2167-2188. ISSN 0960-3115 (2011) [Refereed Article]
The first decade of sequential and cyclical sampling of the saproxylic beetles of twelve freshly felled Eucalyptus obliqua logs at Warra, Tasmania has allowed comparisons between larger-diameter mature and smaller-diameter regrowth log-classes and between successive sampling cycles and years; and consideration of the interplay between these two aspects. The two log-classes support different assemblages, with the mature log-class hosting consistently more species, more unique species, and proportionally more obligately saproxylic species. Assemblages change seasonally and year-to-year, demonstrating succession. While changes in the assemblages of mature and regrowth log-classes follow similar trajectories, they remain distinct at every point in time. These differences remain apparent when considering sub-sets of the assemblages based on the rarity of the species involved, their flightedness, saproxylicity and larval feeding guild. This study suggests a need to incorporate the conservation of coarse woody debris derived from mature trees into production forestry practices. There is a particular need to devise silvicultural and/or planning systems that cater for the retention and long-term recruitment of mature trees, since these are the only source of the larger-diameter logs that were identified in this study as having particular ecological value. Through continuing the Warra long-term log-decay experiment over the next century or more, a more complete picture of the saproxylic beetle fauna will progressively emerge, together with a better understanding of the management requirements of the fauna.