Arthropod fauna of jarrah (Eucalyptus marginata) foliage in Mediterranean forest of Western Australia: Spatial and temporal variation in abundance, biomass, guild structure and species composition

Abstract

A 2 year study (using a branch‐clipping technique) of the arthropod fauna of jarrah crowns (14 m above ground level) in a 7500km2 area centred on Manjimup, Western Australia, yielded 7461 individuals belonging to 396 species. Lepidoptera, Hemiptera and Araneae dominated the fauna in abundance and biomass but Lepidoptera less so in number of species. Consequently, leaf chewers, sapsuckers and predators were the dominant guilds. Most species showed great spatial and temporal variation in their occurrence, with some 73% being recorded on only one or two of the nine sampling occasions. In addition 77% of species were recorded on four or fewer of the 45 trees sampled. Crowns of these trees tended to have highly dissimilar assemblages of arthropods. Dissimilarity between trees was not predictable from the distance between them. Total species richness was greatest in samples collected in summer. Predators and sapsuckers tended to be the most speciose guilds. Within‐stand differences were much less pronounced than between‐stand differences: ants were more abundant on jarrah foliage within 2 m of ground level and the pest defoliator Uraba lugens (Lepidoptera, Noc‐tuidae) was more abundant on foliage of jarrah pole crowns 14 m above ground. The most abundant arthropod, U. lugens, did not reduce appreciably the biomass or abundance of other arthropod groups present in jarrah pole crowns. This is consistent with the paradigm that competition between species of herbivorous insects is infrequent. After comparison with other studies in jarrah forest, we tentatively conclude that there is no single fixed pattern of organization or predictable assemblage of invertebrates on jarrah foliage.

The canopy, bark, soil and litter invertebrate fauna of the Darling Plateau and adjacent woodland near Perth, Western Australia, with reference to the diversity of forest and woodland invertebrates

“…The low proportion of sap-sucking species in the canopy may, in part, result from undersampling of animals that are attached to the foliage through their mouthparts. This is evidenced by the fact that, using branch-clipping procedures, Abbott et al (1992) found proportionately higher abundances of phytophages on jarrah than we did. However, the high level of secondary compounds, such as tannins, found in leaves and cambium in southern Australian eucalypts, are believed by some to have selected for a relatively small suite of phytophages that are evolutionarily suited to feeding on such forage (see discussion by Landsberg and Cork 1997).…”

Age and distance effects on the canopy arthropod composition of old-growth and 100-year-old Eucalyptus obliqua trees

“…Faunal differences may have been more marked if the younger trees had been more developmentally distinct from the old trees. This supposition is weakly supported by the nature and results of the comparisons in the limited previous literature (Abbott et al, 1992;Schowalter, 1995;Martikainen et al, 2000; Sippola and Kallio, 1995). However, many more comparisons are needed to build up an adequate meta data set.…”

“…While there are some data on changes in canopy arthropod biodiversity related to the impact of harvesting (Schowalter, 1995;Winchester and Ring, 1996;Chey et al, 1998;Floren and Linsenmair, 2001), and host plant age (Banerjee, 1981;Abbott et al, 1992;Basset, 2001), very little is known about the arthropod biodiversity of oldgrowth Eucalyptus trees in relation to younger trees (Majer et al, 1997). For Eucalyptus, the only published study on agerelated changes in arthropod communities compares juvenile and sapling Eucalyptus marginata (Abbott et al, 1992). No previous research has investigated the differences in arthropod communities between the canopies of mature and old-growth Eucalyptus trees.…”

Techniques and Methods for Sampling Canopy Insects

“…Branch clipping has the advantage over many other canopy sampling techniques that the species richness or density of insects can be converted directly to units of plant biomass and/or leaf and branch surface area (Schowalter et al 1981, Abbott et al 1992, Winchester & Ring 1996b). This can provide valuable data on herbivore loads and microhabitat preferences of insects in the canopy.…”