Models that Describe Decomposition of Foliar Litter and Roots

Abstract

Models have been used to describe decomposition processes. There are types of models that serve different purposes. Empirical models are statistical in nature and attempt to fit empirical data to mathematical equations. Mechanistic models are theoretical in nature, using a system of equations to describe complex processes. Simulation models simulate the behavior of a system, allowing researchers to manipulate aspects of the model to investigate potential outcomes. This chapter focuses on empirical models, presenting commonly used equations for decomposition patterns: the single exponential and the asymptotic function. The decomposition pattern, indicated by e.g. initial rate and limit value for decomposition is related to litter chemical composition and environmental factors. Nitrogen (N) and manganese (Mn) may be important nutrients for the shape of the pattern. Thus, asymptotic functions have different limit values depending on the litters’ initial Mn concentration with a positive relationship between Mn concentration and limit values ranging from 55 to 100%. Thus, higher initial concentrations of Mn in litter can result in smaller amounts of long-term residue. In contrast, high N availability, both in litter and in soil, e.g. in fertilization experiments has been related to lower limit values and a larger residue.