The overarching goal of this project is to understand carbon and nutrient cycles for a landscape on which terrestrial and freshwater systems are intimately connected in multiple and reciprocal ways. In the Northern Highlands region of Wisconsin, they are studying a spatially complex landscape in which water features make up almost half of the land area, with wetlands (27% of land surface) and lakes (13%) both prevalent throughout the region, interspersed in upland forests. The Ecosystem and Landscape Ecology Lab hypothesize that reciprocal interactions of terrestrial vegetation and lakes, through flows of water, organic carbon, and nutrients, are more complex than previously thought. Improved understanding of these interactions demands a combination of terrestrial and aquatic expertise, in an appropriately integrated research plan.
Terrestrial ecologists have made great strides in understanding the geophysical template, climate, disturbance regimes, and vegetation dynamics that control groundwater, surface water, carbon and nutrient fluxes in the Northern Highlands and other landscapes. Despite these advances, there are considerable gaps in understanding the magnitude and spatial patterns of biogeochemical fluxes. For example, terrestrial ecologists have found important imbalances in the carbon cycle. These gaps may be closed by studies that consider the complete landscape – that is, the integrated behavior of terrestrial upland vegetation, wetlands and surface waters. The goal of this project is to understand how the extent of surface water and wetlands affects ecosystem production, respiration, and spatial flow of organic carbon on complex, heterogeneous landscapes. The approach centers on simulation modeling of hydrology and biogeochemistry, with ground-truthing and calibration data provided by field measurements. The focus is on the Northern Highland Lake District (NHLD) of northern Wisconsin and Upper Michigan, a complex landscape with over 7500 lakes and diverse forested and wetland ecosystems. The research team has developed a new integrated spatial simulation model for hydrology and carbon cycling of the entire NHLD (Cardille et al. 2007), and early results are summarized here. Ongoing work on the project includes the testing of climate scenarios using the simulation model, as well as the development of a full regional carbon budget for this lake-rich landscape.