North Temperate Lakes

The importance of the position of a lake in the landscape relative to hydrologic flow has been a focus of the Long-Term Ecological Research Project, based at the UW-Madison Center for Limnology, for almost two decades. We have found that there are strong patterns in water chemistry, primary productivity, and morphology driven by ground and surface water inputs (Magnuson et. al. 1990, Kratz et al. 1997, Riera et al. in press). Also, lake size and physico-chemical conditions within a lake have been shown to influence community structure in fishes (Tonn and Magnuson 1982, Tonn et al.1990). However, we know much less about how landscape level traits, such as surface water connections, influence biotic diversity and community structure within lakes and whether the species pool changes across watersheds of North-Central Wisconsin (Hrabik and Magnuson 1999). The primary goal of our project is to conduct field experiments that contrast lake chemical and geographical properties and explore the role of those properties in shaping biotic diversity and community structure.

Surprises - large, unexpected changes from apparently small causes -- are common in systems of people and nature. Are these surprises a consequence of the complexity or nonlinearity of natural-social systems? Or can they be explained by simpler processes? Our research addresses this question for systems composed of lakes, their shoreline (riparian) vegetation and land use, and social and economic organizations of lake users. We will study the self-organization of lake users and associated characteristics of shoreline and lake ecosystems. We will determine whether thresholds in riparian organization set the stage for an important class of surprises - collapses of economically important game fish stocks. We will test the possibility that nonlinear dynamics can be used to design manipulations that remove invading crayfish from a lake. If successful, our experiment will cause a self-sustaining removal of an invasive species - a path-breaking ecological restoration.