On the overgrazing problem
A model of optimal range management is developed which explicitly recognises the dynamic interaction between livestock and carrying capacity. Compared with the usual bioeconomic model, the ratio of animals to "carrying capacity" must be too small in equilibrium. Furthermore, it may be optimal to overshoot the equilibrium following a drought. It is conjectured that the severe overgrazing in places like Africa's Sahel occurs not in an equilibrium situation but in times of drought when forces compel herders to hold onto their livestock just when optimality demands that they destock as quickly as possible.