Distribution of invertebrates on foliage in forests of south‐eastern Australia

Abstract

AbstractNearly 1500 foliage samples were collected from a total of 156 plant species, distributed at 16 study sites representing a wide range of forests and woodlands in south‐eastern Australia. Samples were collected in all months. Invertebrates present in samples were counted, sorted into 13 categories, and the number present (> 3 mm in length) converted into density estimates. Densities of all invertebrates combined and invertebrate diversity were also calculated.Despite high variability there were some obvious distributional patterns for most categories. Three major dichotomies affected abundance and distribution of invertebrates: these were presence or absence of flowers, whether the plant species was Eucalyptus or other, and if Eucalyptus, whether the plant species was Symphyomyrtus or Monocalyptus. The presence of flowers in foliage samples increased the abundance of most invertebrate taxa. Compared to foliage of non‐Eucalyptus species, Eucalyptus foliage had more lerp‐forming psyllids and miscellaneous larvae, but fewer Arachnida, Coleoptera, Psocoptera, Hemiptera (other), Thysanoptera, Diptera, and total arthropods. Foliage of Symphyomyrtus species had higher densities of most categories (and particularly lerp‐forming psyllids) than that of Monocalyptus.There were seasonal variations in abundance in most invertebrate taxa, but these patterns were different for Eucalyptus and non‐Eucalyptus species. For most sites abundance of all arthropods combined was lowest in winter, but this decline was not especially pronounced, and was reversed at more xeric sites.For most categories there were significant differences between study sites in abundance and for some this was related to position of sites on a moisture gradient. In general total arthropod densities were highest at intermediate and xeric sites. There were some significant differences in arthropod communities for the same plant species at different study sites.Sample height, plant height, and the ratio of these were relatively unimportant variables. Likewise, the ratio of leaf width: leaf length was not significantly correlated with abundance for any invertebrate category across 128 plant species, but mean leaf size was negatively correlated with densities of Arachnida and total invertebrates. The distributions of some invertebrate categories were inter‐correlated.