The breakdown of shed plant parts (liter) by microbes, called decomposition, is a fundamental ecological process integral to the flow of energy and cycling of nutrients in all ecosystems. Many earlier studies have described how the initial chemical makeup of litter relates to its decomposition rate. But much less is known about the later stages of decay, which are important for long-term stability of soils and ecosystems. If initial chemistry is not in fact related to long-term decomposition, as is usually assumed, then our understanding is much more limited than thought. This project takes advantage of a large set of archived litter samples collected from a wide range of ecosystems over many years. The investigators will combine existing data on litter chemistry with new analyses of these archived samples to explore more general patterns of litter chemistry throughout the entire decomposition process. This project will integrate research and education with undergraduates at the West Campus of Arizona State University that serves a very diverse community with a high percentage of first-generation college students. In addition, a decomposition module will be developed for K-12 teachers to use in Arizona middle and high school science classes. The investigators will take advantage of the multiple institutions involved to coordinate undergraduate student teaching and involvement in research, while centralized training at the University of New Hampshire will enable graduate students to learn new techniques in close collaboration. Finally, in addition to publishing results in peer-reviewed journals, a special session is proposed for a national meeting to engage a larger group of scientists in discussions of this important topic.

This project will determine whether diverse plant litter types maintain their initial chemical differences throughout decay, remaining chemically unique as often assumed, or if decomposing litter follows different chemical trajectories to either converge or diverge over the course of decomposition. Further, this study will determine how these patterns relate to decay rate and identify the local environmental drivers, including climate and decomposer communities, that may influence the patterns and temporal variability in litter chemistry during decomposition. The results of this project will help determine whether the suite of litter chemical characteristics known to influence decomposition follow consistent patterns throughout decay across a range of terrestrial ecosystems that includes forests, deserts and agricultural fields. It will help settle the issue of whether or not initial litter chemistry is the main determinant of decay rates. The project will also document and explain differences resulting from the many analytical methods currently used that should be taken into account in future studies. By leveraging existing data and a large set of archived litter samples, the new resources needed to achieve these objectives are greatly reduced.