Description:

Megan Midgley, PhD,
Soil Ecologist,
Morton Arboretum,

Nitrogen deposition impacts on soil carbon and nitrogen dynamics: The role of mycorrhizal associations in temperate forests

Abstract:Temperate forests receive some of the highest rates of nitrogen (N) deposition in the world. While numerous studies have investigated the effects of N deposition on trees and soils, there is little consensus on why some forests respond positively to N enrichment while others respond negatively. The MANE framework suggests that the type of mycorrhizal association of the dominant tree species in a forest - arbusular mycorrhizal (AM) or ectomycorrhizal (ECM) - unites tree and microbial characteristics with soil C and N dynamics. Given that the relative abundance of AM and ECM trees are evenly distributed across most forests in the Eastern and Midwestern US, the MANE framework may provide a lens for determining how forests with varying tree species compositions will respond to N deposition. Furthermore, as forests provide ecosystem services such as N retention and carbon (C) storage, a unifying framework that explains why forests differ in their sensitivity to N deposition represents a critical frontier in ecosystem science. In this seminar, I will evaluate the hypothesis that variable soil responses to N deposition may be simplified by considering mycorrhizal associations.

Plant Conservation Science Center,