Public policy for management of forest pests within an ownership mosaic

Urban forests provide ecosystem services that are public goods with local (shade) to global (carbon sequestration) benefits and occur on both public and private lands. Thus, incentives for private tree owners to invest in tree care may fall short of those of a public forest manager aiming to optimize ecosystem service benefits for society. The management of a forest pest provides a salient focus area because pests threaten public goods provision and pest management generates feedback that mitigates future risks to forests. We use a game theoretic model to determine optimal pest treatment subsidies for a focal privately owned tree and use an optimization approach to guide targeted public treatment of a representative public tree. We find that optimal public subsidies for private tree treatment depend on assessed tree health and on the prevalence of the pest in the community, considerations absent from many existing programs. Next, by applying our pest treatment policies to a community-scale model of emerald ash borer forest pest dynamics, we predict ash mortality under a range of treatment scenarios over a 50-year time horizon. Our results highlight how designing policies that consider the public goods benefits of private actions can contribute to sustainable land management.