On the Optimality of Limit Cycles in Nature Based-Tourism

Virgin nature, as well as historical and cultural monuments located in National Parks, all form part of our national heritage. Tourism and recre- ation allow visitors to National Parks to enjoy nature, to reinstate, recover and broaden their personal outlook, to experience local history, culture, ora and fauna and to interact with the environment harmoniously. One of the ob- jectives of the administration of a Governmental Institution 'National Park' is to maximize prots from tourism and recreation, where prot is dened as the difference between the revenues from visitors and the sum of expenditures on recreation investments and defensive expenditures for ensuring the preserva- tion of natural and cultural heritage. This paper is an attempt to model some relevant aspects of these prey-predator relations. The model is formulated in terms of optimal control theory, and then is transformed into an `augmented' dynamic system by meas of the optimal choice of control variables resulting form the application of Pontryagin's Maximum Principle. It turns out that, for reasonable parameter values, the optimal trajectory exhibits a cyclical behavior.