Boerner, R. E. J. Department of Evolution, Ecology, and Organismal Biology, Ohio State University 318 West 12th Avenue, Columbus, OH 43210 USA. Unraveling the Gordian Knot: Interactions among vegetation, topography, and soil properties in the central and southern Appalachians. J. Torrey Bot. Soc. 133: 321–361. 2006.—This review focuses on the development of our knowledge of the interactions among vegetation, soil forming processes, topography, and human actions in shaping the forests of the central and southern Appalachians. It proceeds from a review of the studies that led to and cemented the topographic paradigm in forest ecology in the 1940's to a review of the studies of soil development in the region during the 1960's and 1970's. This is followed by a review of how the incorporation of the emerging understanding of edaphic and biogeochemical factors affected studies of vegetation in the Appalachians over the last three decades, with emphasis on studies which have been particularly useful in beginning to unravel the interactions among microenvironment, vegetation, and soil. I then consider a suite of natural factors (storm damage, canopy herbivory, fire) and human disturbances (agricultural intensification, atmospheric deposition) that impact the interactions between forest vegetation and the soil system, and speculate on how viewing the Appalachian ecosystems from a more integrated landscape perspective might affect future attempts to unravel the Gordian Knot.