A novel approach to combine response functions in ecological process modelling

A novel approach to combining response functions, e.g., temperature and soil moisture dependency, is presented. This approach is in analogy of resistances connected in parallel and mathematically to the inverse function of the sum of reciprocal response functions. The approach presented is applicable for a wide range of response functions, and demonstrate better performance as the multiplicative approach if the limiting factor dominates the process rate more than the other factors. It was applied to a gross nitrification data set acquired from beech litter samples in the laboratory using the barometric process separation (BaPS) method. Compared with the minimum and the multiplicative approaches, the best fit was achieved with the novel approach, using the Residual Sum of Squares and r2 values as indicators. Additionally, two examples from the literature were presented to demonstrate the potential and benefits of the approach, which is a good alternative combining two or more response functions.