Abstract
We examine how spiked pepper ( Piper aduncum L., Piperaceae), a shade intolerant, animal-dispersed Neotropical tree, is spreading in the interior of Borneo. Concerned that logging roads might be facilitating this spread, we made a series of observations, relating tree distribution, location and road history, in a concession in East Kalimantan. These roads will connect West Kutai and Malinau Districts and may allow alien plants to disperse from one to the other. We observed that P. aduncum was already well established on the oldest, southern portions of the logging road network, but was absent on the newest roads to the north. A few scattered individuals occur on the roadside as much as 150 km beyond the main areas dominated by P. aduncum, suggesting an occasional ability to achieve long-hop dispersal. Rivers of 30 m width are not a barrier to P. aduncum's spread. Based on road age, we estimate a minimum rate of spread between five and seven km per year. We infer that logging roads are assisting P. aduncum to spread and the tree will become widely established in Malinau District. Prevention of this spread would require urgent, intensive and coordinated control over the length of the road network and, more generally, major restrictions on how such roads are located and managed.
Highlights
Alien plants can cause various changes in tropical ecosystems and pose threats to forest biodiversity [1,2,3]
Considering P. aduncum has managed to reach between 128 and 199 km and accepting that the road is the primary route of this spread, the 27 years of spread indicates a minimum rate of advance between five and seven km per year
P. aduncum might be a concern in areas being managed for timber in a more destructive fashion, and may become a problem even in natural forest areas in the long-term, especially if the canopy was opened up by a recurrence of the major droughts and fires that caused major tree death in nearby regions in 1998 [23] or if these forests are subject to any other destructive events
Summary
Alien plants can cause various changes in tropical ecosystems and pose threats to forest biodiversity [1,2,3]. Around 300 million hectares of the world’s tropical forests – an area almost four times larger than that designated for stricter conservation – are already managed primarily for timber [6]. These forests remain valuable in terms of biodiversity, carbon and other environmental values [7]. Malaysia and Papua New Guinea already have naturalized populations of P. aduncum In these regions P. aduncum has become a significant environmental concern by dominating regrowth vegetation over large areas, displacing native species [17], slowing forest recovery, and interfering with agriculture [1]. Our aim was to map the roadside distribution of this tree species and examine its potential to spread via these roads into new areas
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
