The Construction of Plant Litter Decomposition Curves

Abstract

Quantitative analysis of changes undergone by plant litter during decomposition is a main focus of theoretical and empirical studies of plant litter decomposition. Decomposition curves are most often described by systems of differential equations whose closed-form solutions enable simple estimation of fundamental parameters such as litter decay rate(s). Other potential applications of mathematical models of litter decomposition include analysis of the controls of plant traits vs. decomposers on decomposition and predictions of how litter decomposition responds to ecosystem changes. This chapter provides an overview of the main approaches to modelling plant litter decomposition and drawing decomposition curves produced under various assumptions. The Olson’s negative exponential model has been widely used by freshwater ecologists to summarize and compare results of field and laboratory studies. Yet, it is still unclear where and when the assumption of time invariance of litter decay rate underlying the simple model is met. Process-based models incorporating litter heterogeneity and/or consumer-resource dynamics provide evidence that decomposition does not proceed at constant rate. Thus, relaxing the assumption of time invariance for litter decay rate is a necessary step towards a deeper mechanistic understanding of drivers and agents of plant litter decomposition in aquatic ecosystems.