9630531 Hedin Mechanisms of Base Cation Cycling in Forest Biogeochemical Systems: Application of a New Tool A priority for research in the field of biogeochemistry in the U.S. and other industrial nations is to understand how modern human activities are affecting the integrity and stability of natural ecosystems. It is particularly urgent to understand how forest resources are affected, as indicated by recent scientific reports of increasing degradation in forest health in some areas of North America and Europe, including instances of "forest decline." One of the most important needs for predicting the status of forests over the next century is an improved understanding of how humans are perturbing the natural pathways by which forests feed on mineral nutrients (so called "base cations"). Over the past two years, a new technique has been developed that uses non-radioactive stable isotopes of strontium (isotope 84) to directly trace how forest nutrition is affected by human activities. This research applies this new application to forest ecosystems where human impacts have been minimal to better understand the sources of base cations and how these materials are utilized and cycled.
