Impact of Tamarix Biocontrol on Understory Plant Community Traits
Annie Henry1*, Eduardo González2, Anna Sher3
1 University of Denver, Department of Biological Sciences, Denver, CO, USA; annie.henry@du.edu
2 Colorado State University, Department of Biology, Fort Collins, CO USA; edusargas@hotmail.com
3 University of Denver, Department of Biological Sciences, Denver, CO, USA; anna.sher@du.edu
The biological control agent Diorhabda spp. has spread farther and faster than originally anticipated, leading to the pressing question of what plant communities will replace Tamarix as its dominance is reduced. While previous research has examined plant community response to Tamarix defoliation in terms of species composition, this research uses a trait-based approach for a more mechanistic understanding of the environment-plant community relationship. A functional trait approach focuses on the morpho-physiological characteristics of organisms rather than species identity, to directly relate plant community response (response traits) to environmental filters such as light and water availability and effects (effect traits) on environmental processes, such as resistance to floods through variations in surface roughness. Using a cluster analysis of plant traits, we found five distinct guilds present in Tamarix dominated biocontrol and non-Tamarix dominated reference sites. These guilds were primarily defined by the plants ability to reproduce asexually and to resprout after damage. Secondarily, guilds were defined by drought or anaerobic tolerance, height, seed weight and specific leaf area. Higher cover of guilds that are able to reproduce asexually was associated with higher precipitation and permanent water sources. Guilds that only reproduced sexually were associated with higher temperatures and greater distance to water. Disturbance tolerant understory plants were associated with biocontrol sites with little live Tamarix. This approach will provide managers with a tool to anticipate the effects of Tamarix biological control and more successfully revegetate after removal, based on knowledge of what trait combinations will thrive given specific site characteristics. Ultimately, this approach will also allow us to anticipate ecosystem effects of altered plant communities.