The impact of archaeological clearing on secondary succession in a tropical rainforest

Disturbance events can often create an environment that allows invasive species to colonize, particularly on susceptible island ecosystems. An increasingly common form are anthropogenic disturbances, which are caused by human interactions with the environment. The ‘Opunohu Valley on the island of Mo’orea, French Polynesia experiences continuous disturbance events in the form of forest clearing for archaeological excavations and mapping. This study examined whether archaeological clearing events increased the number of invasive plants during secondary regrowth by surveying four previously clear-cut archaeological sites for invasive vascular plants. There appeared to be no difference across treatments when looking at non-native species, but there was a difference in recent invaders. There was high variation between sites, indicating a possible confounding variable of previous habitation use or number of times cleared which varied across sites. The highest proportion of invasive species were found in a site that was repeatedly cleared for tourism purposes. Cleared archaeological sites overall had no effect on the invasion of non-native species, but may have helped distribute more recent invasive species. Thus, forest management organizations should take more precautions when conducting archaeological clearing and rebuilding prehistoric sites.