Table 1. Vegetation types of the herb layer and simulated environmental factors under which they emerge, as well as their pastoral value, from which a first estimate of biomass production is calculated.

Grazing intensity Dunging intensity Tree cover Pastoral value PV
Eutrophic pasture High High Low 40
Oligotrophic pasture High Low Low 20
Fallow Low Low Low 10
Understory Low Low High 40
The pastoral value is based on vegetation surveys (Gillet and Gallandat 1996, Gillet 2002, 2008), except for understory. Here PV is artificially set to the value of eutrophic pasture, because the lower productivity of understory is expressed by a combined influence of drought and tree cover (see text).