PS 36-80
Factors influencing the spread of false brome from streams and roads in the Andrews Forest, western Oregon
This objective of this study is to investigate which factors have influence on the distribution of false brome at HJ Andrews Forest. The hypotheses of this study are that Brachypodium sylvaticum can be dispersed mainly along roads when B. sylvaticum invades into new habitat at first and then this species may be dispersed along streams and junctions between roads, the tributaries from the roads can make B. sylvaticum invade into near streams. We checked out the distribution and dispersal mechanism of false brome which has been newly invaded into Northwest areas of USA in an experimental forest, H. J. Andrews Forest. All third-, fourth-, fifth-order streams and main streams of Lookout creek in the Andrews Forest were investigated for B. sylvaticum in the Andrews Forest during August, 2012 to July, 2013. The roads in the vicinity of third- or higher-order streams were surveyed to record the locations of B. sylvaticum. Locations of B. sylvaticum were positioned by GPS. The individual counts in each population, substrate texture, associated vegetation and other characteristics were recorded. The distance from the creek and main stream and patch diameter of false brome are estimated in classes of 0-3m, >3-7.5, >7.5-15, >15-30, and >30m along the creek to main stream. All B. sylvaticum patches are mapped in study area using GIS.
Results/Conclusions
Brachypodium sylvaticumwere distributed along roads and streams in the Andrews Forest, and invaded into tributaries between road and stream networks. The amounts and patch size of false brome at clear-cut areas are much higher than those at old growth forest and the occurrence of false brome in forest interior depends upon the presence of false brome at the road. This study showed that the invasion of exotic plants can be accelerated by road and streams networks through water pathways.