Effects of a 1970 restoration planting on soil in the Carleton College Lower Arboretum, Northfield, MN

The species mix in a forest is commonly limited by soil composition. At the same time, the composition and chemistry of a soil can be controlled by the forest above. This study looks at the effects of a 1970 restoration planting (the Earth Day Forest) in the Lower Arboretum of Carleton College on soil chemistry by testing for important elements. The results of the tests are then compared to data from an uncultivated forest (the non-Earth Day Forest). The species mix chosen for the Earth Day Forest in 1970 was markedly different from the original forest, today the restoration planting is dominated by Juglans nigra (Black Walnut), a species not seen in the non-Earth Day Forest. Comparisons of the Earth Day Forest to the non-Earth Day Forest in the fall of 2011 showed that the Earth Day Forest had lower rates of total C and N in the soil, as well as lower rates of soil organic matter. The allelopathic nature of Juglans nigra has drastically reduced diversity in the Earth Day Forest. Due to its lower rate of N immobilization, the succession of Juglans nigra from the 1970 restoration has lengthened the time required for a former agricultural field to return to a pre- agricultural state