The idea for this book started as a series of lunch table conversations revolving around our respective research projects. Torrie's research at the time focused on trophic dynamics in lakes, looking at the interactive effects of food quality (specifically, algal carbon:phosphorus ratio) and predation on Daphnia life history and stoichiometry to better predict the effects of human modification of bottom-up and top-down forces in aquatic ecosystems. Kim's research examined the effects of nutrient availability and herbivore presence on grassland community composition and production across the broad precipitation gradient of the North American Great Plains. In discussing our respective studies, it became evident that our conversations about the interaction of bottom-up and top-down forces across aquatic and terrestrial ecosystems provided different perspectives and important insights that broadened our conceptual base and benefitted our research. This realization prompted us to organize a session for the annual meeting of the Ecological Society of America in 2011 to bring together aquatic and terrestrial ecologists studying the interaction of bottom-up and top-down processes in diverse ecosystems. During the session, similarities and differences in the strength and nature of trophic interactions across ecosystems became evident, stimulating dialogue between aquatic and terrestrial scientists. The success of this session and the satisfying exchange of ideas that resulted inspired this book.

The goal of this book is to provide a cohesive summary of the interaction of bottom-up and top-down processes across aquatic and terrestrial systems, which may serve as a basis for future cross-system studies examining patterns in these important drivers of community and ecosystems processes. In this book, the definitions of “bottom-up” and “top-down” are purposely broad to include a diverse group of studies and perspectives: bottom-up forces include nutrient and resource availability, and top-down forces include herbivores, predators, and parasites. Given the extent of human-induced global change, this topic is particularly timely and important.