Modelling rangeland productivity in response to degradation in a semi-arid climate

We show that a model based on simplified biophysical processes and a single set of parameters for a mixed sward can satisfactorily simulate mixed-species rangeland vegetation. The model also could reproduce year-to-year phytomass dynamics, including for exceptionally wet and dry years. Without calibrating specifically for it, the model was able to reproduce observed water-use efficiency values, indicating a good representation of the relationship between the main limiting factor, water, and productivity. By recalibrating the model using only five parameters associated with degradation, the accuracy of simulated degraded rangeland states was close to that of undegraded rangeland. We therefore consider the Linrange model a good tool for research on rangeland dynamics and degradation resulting from management and climate. We also point to directions of further model improvement, particularly regarding the modelling of parameter changes with degradation states.