Invasive Thistles

An integrated empirical and theoretical investigation of the factors affecting the establishment of invasive Carduus thistles

thistleschematicBiological invasion is a major economic and environmental problem, yet current understanding of the factors affecting invasions is limited.  I am investigating the interacting factors that affect invasion, using a combined experimental and theoretical approach.  The experimental work simultaneously addresses the characteristics of the invader and the properties of the invaded community.  Resources, competitors and natural enemies are manipulated to assess community effects on invasion success.  Characteristics of the invader that facilitate invasion will be assessed using a comparative protocol, by examining the effects of these different communities on two closely related species of non-native thistle (Carduus nutans L. and C. acanthoides L. (musk and plumeless thistle)), both of which are major noxious weeds, especially of pasture systems.  The results will allow us to answer questions about the community and species-specific factors affecting invasive success.  The results will also be used to build mathematical and computer models of the two species in different types of community, and to project their long-term population dynamics under different and/or changing scenarios.  Such modeling studies will provide crucial insights into the factors that affect invasion.  They will also form a firm foundation for ongoing applied research; they will be used to examine potential management strategies for both noxious weeds.

This research will improve our understanding of the processes involved in biological invasions.   At the same time, it will provide practical information to aid in the management of these two noxious weeds.