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Manganese Toxicity and Oxidative Stress in Trees of the Eastern Forest

The eastern deciduous forest of North America is a principal terrestrial ecosystem of primary importance for the economy and ecology of the nation. However, the future vitality of the forest is uncertain because of the unknown effects of social policies affecting land use, atmospheric chemistry and soil nutrient cycling.

This project focuses on manganese (Mn) biogeochemistry as a critical yet poorly understood determinant of forest health that is being influenced by human activities. There is evidence that Mn toxicity is an important factor associated with forest decline in this region, which is worsening with time. We have recently discovered that Mn toxicity in plants is a photo-oxidative stress, which means that it should have significant interactions with other environmental factors such as light intensity, ultraviolet radiation, temperature, and atmospheric ozone. We have preliminary evidence that Mn toxicity also causes photo-oxidative stress in deciduous trees of the eastern forest, and that tree species differ in response to Mn toxicity.

The goal of this project is to gain a better understanding of how forest trees respond to Mn toxicity, focusing especially on genes, enzymes, and processes involved in oxidative stress. This research is exploring a novel dimension of plant responses to the environment with important consequences for ecosystem responses to global change, and with relevance to our management of the forest and social policies regarding atmospheric quality.

This collaborative project including Sam St.Clair in my lab, John Carlson , an expert in tree genetics and molecular biology, and Bill Sharp of Penn State's Institutes of the Environment, an expert in the effects of acid deposition in forest health. The project is currently supported by a grant from the National Research Initiative of the USDA.