Do logging and exotic invasive plants affect tropical rainforests?
Biological invasions present a major concern globally. Plant invaders often take advantage of anthropogenic habitat disturbance and the enormous global network of roads, both of which increasingly threaten the few remaining wilderness areas of the planet. Tropical forests, in particular, continue to be cleared for agriculture and exploited for their commercially valuable hardwoods.
The island of Borneo has been at the forefront of oil palm expansion and timber exploitation over the past few decades. Little of the ancient lowland dipterocarp rainforests remains intact, with most forest segmented by a vast network of over 270,000 km of logging roads and heavily degraded. Despite the rapid pace at which tropical rainforest habitat is being modified, the extent and impact of plant invasions in tropical landscapes remains poorly understood.
At the Stability of Altered Forest Ecosystem (SAFE) project, we examined whether logging is associated with exotic plant invasions into tropical lowland rainforest and the potential influences on understory plant communities. We established 192 vegetation plots across a logging-intensity gradient from primary to repeatedly-logged forest.
Our results showed relatively low current levels of invasion, despite an intensive logging history and widespread occurrence of logging roads. Nevertheless, we revealed concerning trends, such as a strong positive relationship between logging and exotic plant biomass and leaf area index, as well as a broad distribution of the pantropical invader Clidemia hirta.
While our study shows that there still exists a window of opportunity to minimise the impacts of exotic plant invaders, we also caution that to achieve such goal requires urgent prioritisation of strategic management plans to prevent potentially severe negative impacts on the long-term quality of tropical forest.
Read more by downloading the paper here.
Timm F. Döbert, Bruce L. Webber, John B. Sugau, Katharine J.M. Dickinson & Raphael K. Didham (2017) Logging, exotic plant invasions, and native plant reassembly in a lowland tropical rain forest. Biotropica (Online early; DOI: ).