My current research interests focus on how variation in the arrival or timing of species invasions influences species interactions and the establishment of species in communities. I am especially interested in the assembly rules for communities that determine which species succeed or fail to become established in developing communities. The response of ecological communities to disturbances such as fire and flooding are situations well suited for addressing these basic ecological questions and can lead to a better understanding of the factors limiting community composition.

          As part of a long-term post-fire ecological study, my Master's research examined the effects of fire frequency and habitat fragmentation on avian community structure and habitat use in California coastal sage scrub. My results suggest that fire frequency directly affects the size and number of habitat fragments, and that these landscape changes may result in enhanced competitive interactions between resident and migratory birds. Results of this study have important management implications in lieu of the current controversy of prescribed burning in coastal sage scrub habitats, as well as the importance of fragmented habitats as refugia for bird species in urban environments.

          To address my broad research themes, my doctoral research will examine the effects of invasive Saltcedar (Tamarix sp.) on the abundance and distribution of the surrounding riparian wildlife community. Significant work has gone into the investigation of a promising biological control agent for Saltcedar, the Saltcedar leaf beetle (Diorhabda elongata). By using prescribed fire treatments in conjunction with defoliation by Diorhabda elongata, I hope to contribute to the development of an herbivory index to assess the degree of physiological stress caused by defoliation, and establish a “stress threshold” at which the use of fire becomes an effective means of Saltcedar removal and control. In concert with the defoliation and fire control of Saltcedar, revegetation regimes will be evaluated in terms of resistance to future Saltcedar invasion. The outcome of this research will contribute to general ecological knowledge concerning the impacts and management of invasive plant species and allow me to pursue my interests in the assembly rules which structure natural communities.

Publications

Drus, G. 2004. Species Richness Patterns in a Coastal Sage Scrub Bird Community. Master's Thesis. California State           Polytechnic University, Pomona, CA. 55 p.