Changes in litter chemistry during decomposition: pathways and patterns

Working Group Reports

Final reports: 

Final Report

Decomposition of plant litter is a fundamental biogeochemical process, integral to energy and nutrient cycling and soil formation. While many studies have investigated how litter chemical content relates to its decomposition (in terms of C:N:P, lignin content, phenolic content, etc.), most focus only on initial chemistry as an indicator of how litter will behave throughout decomposition. Such studies have improved our predictions of decomposition dynamics, including decay rate; however, our understanding of the factors that govern changes in litter chemistry during decay is incomplete. Many decomposition studies, particularly within the LTER network, have yielded rich amounts of data concerning the chemical content of litter throughout decomposition, but it remains unclear whether litter chemistry follows consistent patterns throughout decomposition across systems (e.g., forest, desert, agriculture, etc.). It is also unclear whether such changes in chemistry throughout decomposition will have a meaningful influence on litter decay rates, or whether initial litter chemistry is the main determinant. Given the large amount of existing data and recent interest in new chemistry methods, our goal is to compile available data, both published and unpublished, to understand the nature of changes in litter chemistry over decomposition (using all available metrics) and identify whether there are similar patterns across systems. We will analyze a compiled litter chemistry dataset using ordination analysis and other techniques to identify general patterns within and across systems. For litters with different initial chemistries, we will ask whether litter chemistry changes throughout decay in a parallel manner based on initial chemistry (as assumed by so many) or whether all decomposing litter converges on similar chemical properties over time. Further, we will also investigate how these patterns relate to different rates of decomposition and decomposer communities across systems, and identify the drivers of decomposition, temporal variability, and the ecological significance of species identify. By using long-term, cross-site data, we will significantly expand our understanding of the nature and importance of litter chemistry changes throughout decomposition, thus informing the design of future decomposition experiments. This workshop will result in the preparation of a manuscript for peer-reviewed publication, with the initial manuscript outline to be created during the workshop session and further development to occur during follow-up meetings at the ASM, as well as after the meeting through video conferencing.