Differences in abundance and diversity of diurnal invertebrates among three Fijian forests, and a comparison of two trapping methods for rapid assessments

Abstract

Apart from some high-profile exceptions (e.g. charismatic long-horned beetles), the ecology and conservation of Fijian invertebrates have received little research attention, and their potential as biodiversity surrogates or indicators is poorly understood. We surveyed diurnal terrestrial invertebrates within three Fijian forest types (lowland, upland, and coastal) using Malaise traps and beating trays to compare invertebrate abundance and diversity among forests. We also evaluated the efficiency of the two trapping methods for rapid invertebrate assessments. Overall, we collected 2584 invertebrates representing 321 morphospecies within 22 arthropod orders. We found significant differences in the abundance and diversity of invertebrates among forest sites for beating-tray samples, but not for Malaise-trap samples. Upland forest had the greatest diversity (Simpsons diversity index, D = 0.98); coastal forest recorded the lowest diversity (D = 0.14), but the greatest abundance of invertebrates. Several orders of invertebrates were relatively abundant across sites and traps (i.e. had high sampling reliability; they included Coleoptera, Hemiptera, Hymenoptera, Lepidoptera, and Diptera), so could be targeted as surrogates for broader biodiversity sampling. Given the urgency with which baseline data are needed across the South Pacific, invertebrate sampling provides a rapid biodiversity assessment tool, including for working in remote areas with few resources.