Feedbacks between species composition and ecosystem processes are central to ecosystem structure and function, an area of research championed by the late Professor Joan Ehrenfeld, who sadly passed away in summer of 2011. By altering species composition, human beings often dramatically change ecosystem functions. Conversely, by altering ecosystem structure and function, we unavoidably change species composition and interactions in ecosystems. Few species alterations are as dramatic as the introduction of invasive species, particularly with respect to their effects on biogeochemical pools and fluxes of materials and energy. Because ecosystem dynamics are often altered through a variety of interacting, mutually enforcing pathways, the net consequences of exotic species invasions on ecosystems often vary greatly and with a high degree of uncertainty. The symposium will synthesize Professor Ehrenfeld’s research in the areas of species changes and ecosystem alteration, and communicate recent research advances towards mechanistic understandings of ecosystem responses to species invasions, addressing the economic, social, and policy consequences of these changes, connecting trophic interactions of plant-soil feedbacks, and quantifying abundance-impact relationships between invasive species and ecosystem response. The advancement of ecology as a scientific discipline and the application of ecological knowledge and understanding to real-world problems depend on the life-long dedication of great ecologists. Professor Ehrenfeld’s distinguished career resulted in major contributions in the areas of ecosystem ecology, wetland ecology, urban ecology, and restoration ecology. Her contributions in the last decade toward understanding the interactions of exotic invasive plants and forest soils are particularly inspirational, and underscore Dr. Ehrenfeld’s commitment to generating ecological knowledge that both enhances basic understanding of ecological systems and informs management decisions. The special symposium will include 8 presentations from colleagues and former students, plus 20 minutes of open discussion at the end of the symposium in memory of Joan’s legacy as a great ecologist, a mentor, and a beloved friend and colleague.