  In this article, we present a graphical user interface software for the
litter decomposition and soil carbon model Yasso07 and an overview of the
principles and formulae it is based on. The software can be used to test the
model and use it in simple applications. Yasso07 is applicable to upland soils
of different ecosystems worldwide, because it has been developed using data
covering the global climate conditions and representing various ecosystem
types. As input information, Yasso07 requires data on litter input to soil,
climate conditions, and land-use change if any. The model predictions are given
as probability densities representing the uncertainties in the parameter values
of the model and those in the input data - the user interface calculates these
densities using a built-in Monte Carlo simulation.
