Forest hydrology - Great Lakes/St. Lawrence region

Study description

Research at the Turkey Lakes Watershed (TLW) began in 1980 in response to concerns over the impacts of airborne pollutants, primarily acidifying substances, on forested ecosystems. From the outset, the project was envisioned to be multi-disciplinary, bringing together researchers in meteorology, biogeochemistry, forestry, hydrology, fish and wildlife, and ecology to understand the aquatic and terrestrial effects of acidic deposition. As environmental issues have evolved over the last twenty years so has research at the TLW. In addition to ongoing monitoring and research on the impacts of acid deposition, there is research on the storage and release of toxic compounds, the manipulation of fish habitat to simulate shoreline development, the evaluation of the effects of climate change/variation, and the impacts of alternative forest harvesting techniques on terrestrial and aquatic systems.

This study has amassed a 20-year data record of flow and chemistry for 13 first-order streams, one of the longest records in Canada, and has contributed significantly to a number of budgeting and modelling efforts. Ongoing data collection includes continuous measurement of stream flow, concentration of the major ions, nutrients and metals, and concentrations of dissolved organic and inorganic carbon. The continued collection and maintenance of the data set is central to this study. Recently reported results show that there is substantial variation between the individual basins in their response to declining acid deposition and changes in climate. We have observed a significant trend in declining water yield from the basins even though precipitation has remained relatively constant. Because of the number of basins monitored and their inherent variability Turkey Lakes is a unique site to study the interactions of climate, disturbance, topography, vegetation, and soils. Four of our gauged basins were included in the harvesting experiment initiated in 1997. Combined with the extensive pre-harvest data, we will be able to accurately determine the hydrochemical response of these basins to harvesting and follow their recovery. This will provide useful knowledge for the development of criteria and indicators of forest harvesting impacts and the data required to develop and validate models. An expanding component of this study addresses questions related to the development of predictive tools. As forest managers and policy makers demand answers to questions of greater scope and complexity, there is a need to develop more general tools that can be applied across the landscape. Traditional empirical models are not suited to the task. What is required is process-based models that accurately characterize the "drivers" so they can be scaled to suit the question at hand. The current focus in this area is the development of a database system to improve the accessibility to and reliability of our long-term data. This will provide the foundation to begin assessing and/or developing models of hydrochemical processes at Turkey Lakes.