- Population biology of invasive plants
- Predicting plant invaders - Weed Risk Assessments
- Global and regional patterns of plant invasions
- Plant-herbivore interactions
- Effects of fire on native and alien plant recruitment in coastal grasslands
St. John 413A
On-going research in my laboratory addresses questions about the ecology and evolution of invasive plants. My students and I have been interested in alien grasses, which seem to outcompete native plants, alter nutrient cycling, and change the frequency of fires in Hawaii. Other projects involve invasive trees (Myrica faya) and Verbascum thapsus, a Eurasian biennial weed. Some of our research has suggested that plant competitive hierarchies are strongly context-dependent, meaning that a plant’s relative competitive ability depends on environmental conditions (e.g. presence or absence of mycorrhizae, fire, drought or abundant nitrogen) and initial starting conditions (e.g. the size or density of the competitor). We are testing whether simple changes in field conditions can be used to alter competitive hierarchies, favoring native species over the invaders. My students also explore interactions between invasive plants and pollinators, herbivores and microorganisms in order to understand the roles that these organisms play in successful and failed plant invasions.
More generally, I have been interested in global and regional patterns and trends among invaders. One recent focus has been on testing screening systems for identifying species that pose a high risk of becoming pests.
Alexander, J. M., C. Kueffer, C. C. Daehler, P. J. Edwards, A. Pauchard, and T. Seipel. et al. 2011. Assembly of nonnative floras along elevational gradients explained by directional ecological filtering. Proceedings of the National Academy of Sciences 108:656-661.
Junker, R. R., R. Bleil, C. C. Daehler, and N. Bluethgen. 2010. Intra-floral resource partitioning between endemic and invasive flower visitors: consequences for pollinator effectiveness. Ecological Entomology 35:760-767.
Jakobs, G., C. Kueffer, and C. Daehler. 2010. Introduced weed richness across altitudinal gradients in Hawai'i: humps, humans and water-energy dynamics. Biological Invasions 12:4019-4031.