Workshop at the Ecological Society of America meetings.  August, 2000. Snowbird, Utah.  Sponsored by The Collaboratory on the Population Biology of Invasive Species, The Nature Conservancy, and The Ecological Society of America.  Co-organized by Ann K. Sakai   and Stephen G. Weller.

Integrating Disciplines to Understand and Address Problems
in  Invasive Species Biology

   Can basic research in population biology and related disciplines help to understand and mitigate the impacts of invasive species on native species and ecological systems?   Many land managers remain unconvinced of the value of basic research to solve management problems. Similarly, many basic researchers are skeptical of the value of using invasive species and invaded communities as research systems to answer fundamental ecological and evolutionary question. The goal of this workshop, sponsored by the Collaboratory on the Population Biology of Invasive Species, The Nature Conservancy, and  Ecological Society of America and organized by Ann Sakai and Stephen Weller (Univ. California-Irvine) is to further the dialogue that enriches scientists' understanding of the application of their basic research to mitigation of the impacts of invasive species on native species and ecosystems.   

   Developing national policies and programs on invasive species are elevating federal efforts to counter the harmful impacts of invasive species on biological diversity.  Effective action, however, will depend on sound scientific knowledge.  Elizabeth Chornesky (Director of Conservation Research, The Nature Conservancy) will  identify where and how more fundamental research in the population biology of invasive species can make a critical contribution to applied action.  For example, basic research may aid in setting priorities to prevent or suppress the most ecologically harmful species and to protect the most vulnerable ecological systems.

   Many vectors are capable of introducing alien species into aquatic systems.  To reduce the number of introductions, one obvious strategy is to reduce the number and movement of vectors, but this often has high costs because many vectors are associated with commerce.  David Lodge and Cindy Kolar  (Univ.of Notre Dame) will talk about a complementary strategy involving basic research--targeting scarce management resources on species and vector management practices that constitute a higher than average risk.  On-going research suggests it is more possible than most ecologists realize to identify high risk species. 

   Predicting invasive ability of plants is both a theoretical issue and an applied problem. Sarah Reichard (Univ. of Washington) will discuss how combining the theory of population biology and practical knowledge of horticulture has resulted in the development of both predictive statistical models and an accurate and easy-to-use decision tree.

   Robert Cabin (USFS Institute of Pacific Islands Forestry) will discuss research to understand and mitigate the effects of alien species and to facilitate regeneration and establishment of native species in Hawaiian dry forests that have been severely fragmented and degraded.  This research has been designed and conducted in close collaboration with the Kona Dry Forest Working Group, a diverse collection of landowners, government and non-profit agencies, and concerned local citizens. General methods for facilitating scientific/land management interactions will also be discussed.

   Woodlands of Tamarix spp. are now the most abundant riparian vegetation type in the US Southwest.  Many Tamarix control projects emphasize elimination of Tamarix via herbicides or biocontrol insects and do not address the underlying factors that resulted in the displacement of the native forest species.  Juliet Stromberg (Arizona State Univ.) will discuss evidence that the re-establishment of native riparian species can be facilitated in some riparian corridors by restoring appropriate stream flow regimes and herbivory patterns.  The ecological consequences of eliminating Tamarix without simultaneously restoring physical site conditions and processes will be discussed.

   Developing predictive spatial models requires detailed information on species biology, soil resources, level and type of disturbance, topography, and connectivity.  Thomas Stohlgren (US Geological Survey) will discuss basic needs of land managers and new approaches in understanding the ecology of exotic plant species in complex landscapes. A primary focus is evaluating "uncertainty" associated with these spatial models. 

   Kimberly With (Kansas State Univ.) will discuss how invasive species can alter landscape structure and dynamics and make the landscape susceptible to further invasion.  Fragmented landscapes are dominated by sink habitat, in which populations are sustained by immigrants from unfragmented source populations.  Adaptations by native species in response to an invasive species may be swamped by immigrants from outside populations.  A landscape perspective is thus ultimately required to understand the source-sink dynamics of populations and whether landscape management can restore population sinks to population sources for native species.  Managing or restoring landscapes so as to preserve overall habitat connectivity may help to minimize the spread of invasive species across landscapes.