For successful ecosystem management and biodiversity conservation, in addition to ecological and evolutionary processes, we need to consider social and economic influences on the management target. Here, we introduce four models that address economic and social aspects of human society in the context of ecosystem management.
- Lake water pollution. Players choose between cooperative (but costly) option and economical option. Their decision is affected by the fraction of cooperators in the community and by the importance of water pollution problem. This social dynamics is coupled with the dynamics of lake water pollution. Oscillation of large amplitude is generated if social change occurs faster than ecosystem responses.
If phosphorus is removed more effectively either from the inflow or from the lake water, the pollution level may increase (rather than decrease) due to the decline in people's willingness to cooperate (paradox of nutrient removal).
- Herders in a southern Mongolian rangeland. Herders choose foraging sites for their animals in the dry season. If grazing pressure is very strong, the grass biomass becomes depleted and more herders choose to move their animals to an alternative rangeland. They may return to the focal rangeland when the quantity and quality of the grass improves. The system may exhibit bistability with a strong dependence on the initial condition or perpetual large-amplitude fluctuation. Implications for rangeland management are discussed.
- Profit-sharing of plantation management. Illegal logging is a very serious threat to tropical forests. The owner chooses the age of trees to cut, and the workers choose their monitoring effort to prevent illegal logging. After the trees were removed, the owner hires workers to replant young trees. Under the presence of illegal logging pressure, the owner may find it profitable to share the income by selling logs with the workers to solicit their monitoring efforts.
- Graduated sanction for common pool resource management. From field studies, E. Ostrom discovered the severity of punishment to rule deviators need to increase with the amount of harm caused by the selfish action. We conclude that graduated punishment is the most efficient way to ensure cooperation when evaluation errors are unavoidable and when the social group is heterogeneous with respect to the sensitivity of its members to utility difference.