The seasonality of arboreal arthropods foraging within an Australian rainforest tree

Abstract

Abstract. The seasonality of arboreal arthropods foraging within the crown of the canopy tree Argyrodendron actinophyllum. Edlin (Sterculiaceae) was studied in a subtropical rain forest near Brisbane, Australia, during 2 years with interception traps and restricted canopy fogging. Minimal air temperatures explained most of the seasonal variance in arthropod‘density activity'. However, the host phenology was important for several phytophagous groups. Rainfall, relative humidity and lunar phase influenced arthropod activity slightly. Seasonal ranges were significantly different among arboreal guilds and were related to food resource availability in time, associated with both the host and the rainforest environment. Seasonal peaks of herbivores were more marked than in tropical rain forests, but less sharp than in temperate woodlands.' Quantitative changes in arthropod density activity and abundance were important for most groups, with a marked trough during cool and dry months. The numerical contribution of most arthropod guilds to the arboreal community was not constant throughout the year. Seasonal changes in the species composition of the arboreal community appeared not as a succession of well‐defined subcommunities throughout the year, but as a continuum of species of extended seasonal ranges. This subtropical insect‐plant system presented several phenological features which were classified under tropical and temperate characteristics. This partition is open to discussion.