Numerical stability considerations in the simple mass balance calculation of critical loads for acidity

This paper identifies sources of numerical instability within the critical loads for acidity calculation developed by Sverdrup and de Vries and examines the effects of these instabilities on critical load calculations for sitka spruce forests in Wales. It is shown that the instabilities can introduce large changes in the calculated critical load for small changes in the calculation parameters and that it is essential for researchers to be aware of such unstable parameter regions before applying the equations to experimental situations or to regional mapping.