ManagementrulesManagementrules may be sorted in two groups : strategic decisions at the time of setting up a new plot, and tactical decisions when managing the established plot. The review of tactical management rules is necessary to build the Decision Making Module (DMM) that will drive the HySAFE model. This review will allow us to decide if we need to take decisions at a day time step or if the year time step is enough. This will have a major influence for the structure of the HySAFE model. When managing mature silvoarable systems, such as the Dehesa or traditional Greek plots, very few strategic decisions can be made : tree species, tree spacing, tree canopy shape are imposed. We will try to design a HySAFE model that will be able to simulate mature plots, but it must be said that the initial description of the tree may be difficult in that case.
List of strategic decisions necessary at the start of a simulation (plot level) The sensibility to these decisions will be studied by parallel runs of the model. Decisions at the farm level (where should I localise a SA plot, what area of SA in my farm, should I delay the plantations over time…) are not considered here. The following 11 decisions have been identified : 1. Minimum size of the plot 2. Width for the headlands 3. Tree pattern : irregular, regular [rectangular, quincunx] 4. Tree spacing between rows 5. Tree spacing within row 6. Tree line orientation, Tree line slope 7. Tree species [timber tree, dual purpose tree], [sole species, mixture of species] 8. Tree protection [no, net, tube] 9. Accompanying understorey on the tree line [grassing, shrubs, Christmas trees] 10. Soil preparation [uniform across the plot, specific for the tree line], [ploughing, subsoiling] 11. Initial crop rotation (including water saving fallow in dry systems) The influence of these decisions on the plot results will be obtained by running simulations with the same management rules but different values for the initial strategic decisions. In the case of mature systems such as the Dehesa in Spain or some Greek plots with old trees, no strategic choices are offered. In most cases, the trees are not aligned, but this should not be a difficulty.