Road age and its importance in earthworm invasion of northern boreal forests
Article first published online: 5 AUG 2008
© 2008 The Authors. Journal compilation © 2008 British Ecological Society
Journal of Applied Ecology
Volume 46, Issue 1, pages 28–36, February 2009
How to Cite
Cameron, E. K. and Bayne, E. M. (2009), Road age and its importance in earthworm invasion of northern boreal forests. Journal of Applied Ecology, 46: 28–36. doi: 10.1111/j.1365-2664.2008.01535.x
- Issue published online: 14 JAN 2009
- Article first published online: 5 AUG 2008
- Received 30 October 2007; accepted 7 July 2008; Handling Editor: Yvonne Buckley
- boreal forest;
- earthworm invasion;
- introduction mechanisms;
- invasive spread;
- linear features;
- non-native species;
- road age
- 1Roads are an important conduit for the spread of invasive species. Road age is a key factor that could influence the susceptibility of roads to invasion as older roads are typically subject to higher cumulative levels of human disturbance and propagule pressure than younger roads. We investigated the effects of road age on the spread of non-native earthworms, which act as ecosystem engineers.
- 2We sampled earthworms and habitat variables at 98 roads in the boreal forest of Alberta, Canada, to determine the influence of road age on non-native earthworm occurrence at the landscape level. The extent and rate of local spread were also assessed at seven sites adjacent to old and young roads. Generalized estimating equations and zero-inflated negative binomial regression were used to analyze landscape- and local-level results, respectively. We used our models to create maps that predict the current and potential future extent of earthworms in north-eastern Alberta.
- 3Probability of earthworm occurrence and extent of spread increased as road age increased. Areas closer to agriculture and towards the south and west of our study area were also significantly more likely to be invaded by earthworms.
- 4Our spread model indicated that approximately 9% of the boreal forest of north-eastern Alberta is likely invaded by earthworms currently. This is projected to increase to 49% of suitable forest habitat over the next 50 years as human development intensifies in this region.
- 5Synthesis and applications. Although the effects of roads and linear features are commonly investigated in relation to native species, our results emphasize the importance of considering the impacts of linear feature creation on the spread of invasive species. We demonstrate that road age in particular can be an important factor affecting the spread of invasive species. In the boreal forest, reducing the number of roads being constructed, restricting traffic, and reclaiming temporary roads will be critical to reduce the future extent of earthworm invasions.