Beetle communities associated with the tree fern Dicksonia antarctica Labill. in Tasmania

Tree ferns are a conspicuous element of many wet forests in Australia, and in increasing demand in export markets, but little is known about their beetle fauna. The tree fern Dicksonia antarctica Labill. was sampled over four seasons at four sites in Tasmania. A total of 108 species of beetles, representing 35 families, were collected from three discrete microhabitats on 80 individual tree ferns. Beetle numbers were highest in the crown litter, then live fronds and least from the trunk. Curculionoids were the most diverse and abundant group of beetles and an anthribid genus, Xynotropis Blackburn, was most numerous. The crown litter was numerically dominated by species from four families, Anthribidae, Leiodidae, Ptiliidae and Staphylinidae. Two other families, Latridiidae and Coccinellidae, were most abundant on the live fronds, while Tenebrionidae, Staphylinidae and Anthribidae were common on the trunks. Predators, followed by fungivores contributed the highest proportion of species richness, however fungivores, spore-feeders and detritivores were most abundant as individuals. Despite a large foliar biomass, herbivores were notably few in numbers and diversity. The beetle assemblage on each of the three microhabitats associated with tree ferns was distinctive and characterised by sets of species that displayed some degree of geographical variation. Indicator analysis revealed that 13 species were broadly characteristic of site-by-microhabitat combinations. For exported tree ferns, the beetle fauna appears to be low in pest potential.