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  • Multi-objective models for ...
    González-González, José Mario; Vázquez-Méndez, Miguel Ernesto; Diéguez-Aranda, Ulises

    Forest policy and economics, March 2022, 2022-03-00, 20220301, Volume: 136
    Journal Article

    In this study we present several multi-objective models for forest harvest scheduling in forest with single-species, even-aged stands using a continuous formulation. We seek to maximize economic profitability and even-flow of timber harvest volume, both for the first rotation and for the regulated forest. For that, we design new metrics that allow working with continuous decision variables, namely, the harvest time of each stand. Unlike traditional combinatorial formulations, this avoids dividing the planning horizon into periods and simulating alternative management prescriptions before the optimization process. We propose to combine a scalarization technique (weighting method) with a gradient-type algorithm (L-BFGS-B) to obtain the Pareto frontier of the problem, which graphically shows the relationships (trade-offs) between objectives, and helps the decision makers to choose a suitable weighting for each objective. We compare this approach with the widely used in forestry multi-objective evolutionary algorithm NSGA-II. We analyze the model in a Eucalyptus globulus Labill. forest of Galicia (NW Spain). The continuous formulation proves robust in forests with different structures and provides better results than the traditional combinatorial approach. For problem solving, our proposal shows a clear advantage over the evolutionary algorithm in terms of computational time (efficiency), being of the order of 65 times faster for both continuous and discrete formulations. •A new metric for measuring forest regulation using continuous decision variables is designed.•Continuous multi-objective models for forest harvest scheduling are formulated.•A scalarization technique plus a gradient-type method is used to obtain the Pareto frontier.•An intuitive graphical tool for forest decision making is proposed.