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Persistence of corruption: an evolutionary game theory motivated by illegal logging in tropics Iwasa, Yoh


Illegal logging is a serious threat to plantations in the tropics. Here, we study the coupled dynamics of Social-Ecological systems shedding light of two different aspects. [1] We examined the roles of profit-sharing in plantation management strategy in a dynamic game model. The model assumes that the owner chooses the age of the trees to be harvested and the local people choose their level of monitoring effort to prevent illegal logging with surveillance. After the trees are removed, the owner hires local people to replant young trees. Dynamic optimization analysis revealed that, under the pressure of illegal logging, the owner may find it profitable to share harvesting profits with the local people to enhance their surveillance effort. The profit-sharing rate optimal to the owner depends on the rate of natural disturbance, faster future discount rate, and a higher cost of replanting. [2] Cooperation can be sustained by institutions that punish free-riders. Such institutions, however, tend to be subverted by corruption if they are not closely watched. Monitoring can uphold the enforcement of binding agreements ensuring cooperation, but this usually comes at a price. The temptation to skip monitoring and take the institutionâ s integrity for granted leads to outbreaks of corruption and the breakdown of cooperation. We model the corresponding mechanism by means of evolutionary game theory, using analytical methods and numerical simulations, and find that it leads to sustained or damped oscillations. The results confirm the view that corruption is endemic and transparency a major factor in reducing it. Lee, J-H., Y. Kubo, T. Fujiwara, R.M. Septianad, S. Riyantod, and Y. Iwasa. 2018. Profit sharing as a management strategy for a state-owned teak plantation at high risk for illegal logging. Ecological Economics 149, 140-148. Lee, J-H, Y. Iwasa, U. Dieckmann, and K. Sigmund. 2019 Social evolution leads to persistent corruption. PNAS 116, 13276-13281.

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