On the Impact of Exotic Naturalized Trees in the Landscapes of Papua New Guinea - the situation in Bulolo and Wau

Abstract

Exotic tree species are tree species that have been introduced into an area outside their normal distribution. Over the years, exotic plants have been introduced in Papua New Guinea (PNG) for aesthetic, agricultural, landscaping, and many other uses. Today, some of these plant species are noticeably dominating the natural ecosystems, particularly the disturbed landscapes, where they are suppressing regeneration of native plant species. This is the trend of species composition expected under the disturbance following from climate change and anthropogenic and natural disasters. Little is known about their rate and extent of their distribution, potential benefits and negative impacts on the environment and the ecosystem as a whole. The natural forests often are not able to rebound from alteration of forests by anthropogenic activities through agricultural farming practices, logging, mining, infrastructural development and settlements, and also natural disasters. The rate and extent of the exotic tree species dominating the vicinity in and around the township of Wau and Bulolo, namely, Albiziachinensis (Fabaceae), Leucaena leucocephala (Fabaceae), Pinus caribaea (Pinaceae), and Piper aduncum (Piperaceae, Samanea saman (Fabaceae) and Spathodea campanulata (Bignoniaceae) were assessed using aerial images to demonstrate the actual formation of forest communities by exotic tree species in a PNG landscape.

The survey data demonstrated a positive impact that exotic tree species can naturalize well into the landscape ecosystem they thrive in, forming new forest communities. Their spread has had both beneficial and negative impacts on natural landscapes, and community livelihoods.