Geometrid moth species richness, distribution and community composition in different forest types of Papua New Guinea

As the major group of herbivorous insects, moths are highly significant in natural ecosystems. In collaboration with the Papua New Guinea (PNG) multipurpose National Forest Inventory (NFI) survey, this study investigates the species richness, distribution and community composition of Geometrid moths (Lepidoptera) in PNG’s tropical forests and analyses environmental drivers of the geometrid community structure. By providing a baseline assessment of an important order of insects that can serve as an indicator for broader biodiversity, this study informs how biodiversity assessments can be better integrated into the planning of forest conservation initiatives, particularly those related to REDD+ and forest carbon offset developments. The research was conducted over 3 years at 38 NFI clusters throughout six provinces: Eastern Highlands, Western Highlands, Morobe, Madang and West New Britain and Central Province. Moths were collected from dusk to before midnight (18:00 h to 22:00 h) using a manual light trapping method for four nights per site, with a total of 152 light trap samples. Results included a total of 11,830 specimens from 1,108 morphological species from lowland and montane forests in disturbed (degraded and/or logged) and primary forests. Elevation and forest disturbance are the main variables that influence the distribution of species. Species richness was low in montane undisturbed forests compared with lowland (disturbed and primary) forests and montane disturbed forests. Species similarity between light trap samples tends to decrease as elevation increases. Geometrid moth species were arranged into two main orders of community composition according to the forest types: montane (disturbed and/or primary) forests species and lowland (disturbed and/or primary forest) species as per the samples.