Moth assemblages as indicators of environmental quality in remnants of upland Australian rain forest

1. Despite great concern about the effects of fragmentation on biodiversity , quantitative studies are still scarce with respect to many major groups a nd 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 b asalt on the Atherton Tablelands in tropical north Queensland, Australia. T hree sites had never been cleared, three secondary sites had substantial re growth, and three sites were newly cleared. 3. A total of 15 632 moths of 835 species was collected, counted and identi fied. These represent more than 17% of the named Australian fauna of our ta rget families. 4. A principal components analysis (PCA) indicated clear discrimination amo ng assemblages based on forest type. This discrimination did not differ qua litatively 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 distu rbance, were the Arctiinae, Amphipyrinae, Catocalinae, Hadeninae, Heliothin ae, Hypeninae, Noctuinae, Plusiinae, Hermeniidae and Phycitinae. In contras t, a number of subfamilies showed a marked decrease in relative abundance w ith increased disturbance, namely Ennominae, Geometrinae, Larentiinae, Oeno chrominae, Epipaschiinae, Lymantriidae and Anthelidae. 6. A weighted sum with importance values based on the eigenvalues associate d 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 know n and expected host-plant patterns. The results show how moth assemblages a re powerful indicators of forest disturbance, and should prompt parallel st udies elsewhere in the world.