Cooperative Fish and Wildlife Research Units Program: Pennsylvania
Education, Research and Technical Assistance for Managing Our Natural Resources

Understanding cross-scale interactions (CSIs) is a critical research frontier in macrosystems ecology that extends across all environmental sciences. A CSI exists where a driver at one scale, such as local land use, interacts with a driver at another scale, such as regional climate. These CSIs can lead to nonlinear and often unexpected relationships between drivers and responses. Unfortunately, general properties of CSIs, such as the conditions in which they occur, are largely unknown, partly because they have been quantified in only a few instances. We use lakes and their major nutrients (phosphorus, nitrogen, and organic carbon) as a model system because lakes are affected by many of the main classes of drivers postulated to be a part of CSIs (e.g., connectivity, land use, and climate), and because there is a wealth of existing data and knowledge from small-scale studies regarding possible mechanisms through which drivers could interact across scales.