Research Interests

On-going research in my laboratory falls into two general areas: 1) Ecology and evolution of invasive plants and 2) Plant-animal interactions. In the area 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. Some of our research has suggested that plant competitive hierarchies are context-dependent, meaning that a plant’s relative competitive ability depends on environmental conditions (e.g. presence or absence of mycorrhizae, fire, drought or 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 abilities, favoring native species over the invaders.

A second ongoing study focuses on the evolution of introduced mullein (Verbascum thapsus) in the Hawaiian Islands. This invasive pest was introduced more than 50 years ago, and some plants now exhibit a bizarre growth form not reported from the plant's native range. The process of invasion provides many opportunities for rapid evolution. We are testing whether this strange growth form in Verbascum has a genetic basis and using field experiments to determine how the unusual growth form affects the plant's fitness and ability to spread in the Hawaiian Islands.

More generally, I have been interested in global and regional patterns and trends among invaders. One recent focus has been on testing a pro-active screening system that would reduce new invasive plant introductions by identifying those species pose a high risk of becoming pests. The system can also be used to identify high-risk species among those exotics already being planted in Hawai‘i.

In the area of plant-animal interactions, we have an ongoing project involving ambrosia beetles and their mutualistic ambrosia fungi. Ambrosia beetles depend on their ambrosia fungi as a sole source of food. We have found that ambrosia beetles in Hawai‘i carry different strains of fungi (some of which are pathogenic to plants), and we are interested in the implications of this for both the fitness of the beetles and the fitness/selection of host plants. Also in the area of plant-animal interactions, we have ongoing projects examining the pollination ecology of native and alien plants, including hybridization between them and its consequences. In Hawai‘i, the natural pollinators of many endemic plants remain undocumented. Furthermore, natural ecosystems have been altered by the introduction of alien pollinators (e.g. European honeybees) and alien congeneric plants. This situation provides many unique opportunities for applied and theoretical studies in ecology and evolution.

Selected Publications

Daehler, C.C. 2005. Upper-montane plant invasions in the Hawaiian Islands: Patterns and opportunities. Perspectives in Plant Ecology, Evolution and Systematics 7:203-216.

Daehler, C. C. and Goergen, E. M. 2005. Experimental restoration of an indigenous Hawaiian grassland after invasion by buffel grass (Cenchrus ciliaris). Restoration Ecology 13: 380-389.

Mueller Dombois, D., and C. C. Daehler. 2005. The PABITRA project: Island landscapes under global change. Pacific Science 59:133-139.

Krushelnycky, P.D., Joe, S.M., Medeiros, A.C., Daehler, C.C. and Loope, L.L. 2005. The role of abiotic conditions in shaping the long-term patterns of a high elevation Argentine ant invasion. Diversity and Distributions 11:319-331._

Py_ek, P., C. C. Daehler, M. A. Davis, and K. Thompson. 2004. Plant invasions and vegetation succession: closing the gap. Bulletin of the Ecological Society of America 85:105-109.

Daehler, C. C., J. S. Denslow, S. Ansari, and H. Kuo. 2004. A risk assessment system for screening out invasive pest plants from Hawai'i and other Pacific Islands. Conservation Biology 18:360-368.

Daehler, C. C. 2003. Performance comparisons of co-occurring native and alien plants: Implications for conservation and restoration. Annual Review of Ecology and Systematics 34:183-211.

Stampe, E., and C. C. Daehler. 2003. Mycorrhizal species identity affects plant community structure and invasion. Oikos 100:362-372.

Goergen, E., and C. C. Daehler. 2002. Factors affecting seedling recruitment in an invasive grass (Pennisetum setaceum) and a native grass (Heteropogon contortus) in the Hawaiian Islands. Plant Ecology 161:147-156.

Daehler, C. C., and N. Dudley. 2002. Impact of the black twig borer, and introduced insect pest, on Acacia koa in the Hawaiian Islands. Micronesica 6(Supp.):35-53.

Lockwood, J. L., G. J. Russell, J. J. Gittleman, C. C. Daehler, M. L. McKinney, and A. Purvis. 2002. A metric for analyzing taxonomic patterns of extinction risk. Conservation Biology 16:1137-1142.

Carino, D. A., and C. C. Daehler. 2002. Can inconspicuous legumes facilitate alien grass invasions? Partridge peas and fountain grass in Hawaii. Ecography 25:33-41.

Daehler, C. C., and N. Dudley. 2002. Impact of the black twig borer, and introduced insect pest, on Acacia koa in the Hawaiian Islands. Micronesica 6:35-53.

Anderson, R. C., D. E. Gardner, C. C. Daehler, and F. C. Meinzer. 2002. Dieback of Acacia koa in Hawaii: ecological and pathological characterstics of affected stands. Forest Ecology and Management 162:277-290.

Daehler, C. C. 2001. Darwin's naturalization hypothesis revisited. American Naturalist 158:324-330.

Daehler, C.C. and D. A. Carino. 2001. Hybridization between native and alien plants and its consequences. Pp. 81-102 In J.L. Lockwood and M.L. McKinney, eds. Biotic Homogenization: The loss of diversity through extinction and invasion. Kluwer Academic Publishers, New York.

Goergen, E., and C. C. Daehler. 2001. Reproductive ecology of a native Hawaiian grass (Heteropogon contortus; Poaceae) versus its invasive alien competitor (Pennisetum setaceum; Poaceae). International Journal of Plant Science 162:317-326.

Daehler, C.C. and D.A. Carino. 2000. Predicting invasive plants: Prospects for a general screening system based on current regional models. Biological Invasions 2: 92-103.

Carino, D.A. and C.C. Daehler. 1999. Genetic variation in an apomictic grass, Heteropogon contortus, in the Hawaiian Islands. Molecular Ecology 8: 2127-2132.

Daehler, C.C., C.K. Anttila, D.A. Ayres, and D.R. Strong. 1999. Evolution of a new ecotype of Spartina alterniflora (Poaceae) in San Francisco Bay. American Journal of Botany 86: 543-546