Moth assemblages as indicators of envornmenal quality in remnants of upland Australian Rainforest

Abstract

1. Despite great concern about the effects of fragmentation on biodiversity, quantitative studies are still scarce with respect to many major groups and important environments. Well-studied natural reference sites are few. 2. Extensive light trapping surveys for moths were thus carried out in both dry and wet seasons in nine remnants of complex notophyll vine forest on basalt on the Atherton Tablelands in tropical north Queensland, Australia. Three sites had never been cleared, three secondary sites had substantial regrowth, and three sites were newly cleared. 3. A total of 15 632 moths of 835 species was collected, counted and identified. These represent more than 17% of the named Australian fauna of our target families. 4. A principal components analysis (PCA) indicated clear discrimination among assemblages based on forest type. This discrimination did not differ qualitatively between seasons (although abundance levels of moths did) but the pattern was most evident in the smaller dry season samples. 5. Taxa, the relative abundance of which increased significantly with disturbance, were the Arctiinae, Amphipyrinae, Catocalinae, Hadeninae, Heliothinae, Hypeninae, Noctuinae, Plusiinae, Hermeniidae and Phycitinae. In contrast, a number of subfamilies showed a marked decrease in relative abundance with increased disturbance, namely Ennominae, Geometrinae, Larentiinae, Oenochrominae, Epipaschiinae, Lymantriidae and Anthelidae. 6. A weighted sum with importance values based on the eigenvalues associated with each of these taxa derived from the PCA is a powerful predictor set of forest quality. 7. These differential responses may be explained on the basis of broad known and expected host-plant patterns. The results show how moth assemblages are powerful indicators of forest disturbance, and should prompt parallel studies elsewhere in the world.