Assessing biodiversity 'sampling packages': how similar are arthropod assemblages in different tropical rainforests?

Arthropod sampling protocols have been applied to four areas of undisturbed rainforest in Australia and Borneo at sites located between 28° S and 4° N. Seven different trapping methods have been used in each case following a strictly comparable protocol applied during single wet-season surveys at each location. A number of large scale patterns across sites correlated with latitude, altitude and/or biogeographical history are evident at the ordinal level. The results are used to evaluate two key ideas in biodiversity survey. The first tests questions of the constancy of particular trap types in terms of the target animals. The second attempts to design an efficient multiple method sampling 'package' for rapid biodiversity assessment. Across all sites similar traps behaved in a similar manner in terms of the profile of arthropods that they caught although Malaise traps and pitfalls are particularly 'constant' in this regard. Subsets of both trapping methods and target taxa are identified which will maximise the opportunities for detecting between site differences.     

Diversity patterns of eucalypt canopy arthropods in eastern and western Australia

1. As part of a larger study on canopy arthropods and birds, a 1‐year chemical knockdown study was carried out in one Western Australian forest, where jarrah Eucalyptus marginata and marri E. (Corymbia) calophylla were sampled, and one eastern Australian (New South Wales) forest, where narrow‐leaved ironbark E. crebra and grey box E. moluccana were sampled. 2. Ten trees of each species were sampled during each of the four seasons and the arthropods were sorted to morphospecies level. This paper documents the foliage‐associated component of arboreal arthropod communities and compares arthropod species richness within orders and families, between tree species, and between the two forest types. 3. Hymenoptera, Coleoptera, Diptera, and Araneae were the richest in species. Nine hundred and seventy‐six species in 173 families were found in the eastern Australian forest, while 687 species in 176 families were found in the western Australian forest. Only 53% of families were common to both forests, but almost half the families recorded were represented by fewer than five species. Species overlap between tree species in each region was 40–53%. 4. Analysis using nonparametric bootstrapping procedures showed that sampling of foliage was comprehensive and that only 4–9% more species would be expected with more intensive sampling of the canopy. Absolute richness, as well as differences between tree species and regions, therefore appear to be real and not the result of sampling errors. As a consequence, arthropod species richness in Australian eucalypt forests is shown to be substantially greater than previous estimates.     

Branchlet shaking: A method for sampling tree canopy arthropods under windy conditions

Abstract Chemical knockdown is a commonly used method for sampling canopy arthropods. The procedure is susceptible to high winds and in certain conditions may be virtually unusable. Here we introduce a new procedure, branchlet shaking, and compare it with chemical knockdown. Samples produced by branchlet shaking yield fewer arthropods per tree and tend to miss some larger (>1.0cm) and some smaller (<0.2cm) animals. However, the two procedures generally produce data which can portray similar information about the canopy fauna. It is concluded that although chemical knockdown is a superior sampling procedure, branchlet shaking is a possible alternative for situations where chemical knockdown is impractical. Interpretation of the data must, however, take into account the limitations of the branchlet shaking procedure.