Environmental and Ecosystem Management
I use mathematical modeling approaches to study how our society could sustainably manage our environment and our ecological systems. My modeling approaches include methods from Theoretical Ecology as well as Environmental and Resource Economics. In particular, I am interested in (1) finding cost-effective solutions for the management of biological populations, and (2) developing effective environmental policies for cases in which multiple agents, such as land-owners and countries, manage the same ecosystem. A major recent focus of my research has been on how to mitigate the accelerated infiltration of harmful species, such as invasive species, pests, and diseases. I also study the management of global warming and harvesting by multiple agents.
Cost-effective ecosystem management
Successful ecosystem management necessitates determination of how to manage ecosystems cost-effectively. For example, how can we restore or conserve ecosystems in a way that minimizes the net costs over time due to both (i) treatment by humans and (ii) environmental damages. I use optimization models to examine how to combine multiple actions to restore ecosystems and to manage invasive species (see publications [7, 8, 14, 20]).
Management of harmful species by multiple agents
One of the greatest challenges for reaching sustainable environmental management is to promote cooperation and coordination among the multiple agents that manage the same ecosystem. This challenge may occur at all scales, from local ones where agents may be land-owners, to global ones where agents may be countries. In particular, the core of the problem arises as each agent may aim to achieve her/his/its own objective, and therefore, the agent might not care enough about the damages to other agents. In my research, I use dynamic game theory models to find mechanisms that enable multiple agents to cooperatively manage harmful species, such as invasive species, parasites, pests, and diseases. I showed, for example, that slow treatment of the harmful species may promote a stable solution in which multiple agents contribute to its treatment (see publication). I also showed that the abatement of a harmful species population could be faster if only one or a few agents work in the same area, but multiple agents working together in the same area can better control the population to keep its density lower  (see video presentation). In addition, I showed that, in some cases, agents that have lower benefits from the abatement of the harmful species may need to contribute more than some of the agents that have higher benefits . I also examined the role of information sharing among the agents  and the role of farmers' behavior . In a recent work, I also examine applicatins to the management of the novel Coronavirus by multiple authorities .
Environmental management at the global scale and economic discounting
A major challenge in environmental policymaking is determining whether and how fast our society should adopt sustainable management methods. These decisions may have long-lasting effects on the environment, and therefore, they depend critically on the discount factor, which determines the relative values given to future environmental goods compared to present ones. The discount factor has been a major focus of debate in recent decades, and nevertheless, the potential effect of the environment and its management on the discount factor has been largely ignored. I examine how the over-harvesting of natural resources should be incorporated in climate policy and vice versa [15, 17]. In particular, I showed in a recent paper  that, to maximize social welfare, policymakers need to consider discount factors that depend on changes in natural resource harvest at the global scale. Particularly, the more our society over-harvests today, the more policymakers should discount the near future, but the less they should discount the far future. This results in a novel discount formula that implies that, to maximize social welfare, significantly higher values need to be assigned to future environmental goods.
Community and spatial ecology
The spatial structure of ecosystems and habitats plays a central role in allowing persistence and coexistence of many species. I'm interested in how connectivity and migration rates shape multimodal body-size distributions , promote persistence  and change the roles of local versus regional biodiversity in predator-prey populations .
Evolution of social behavior
A variety of social behaviors and traits encompass a tradeoff between the competitive abilities of their individual carrier and the reproductive abilities of either (i) the carrier itself (asymmetric traits) or (ii) the neighboring population (cooperative/defective traits). I am interested in (i) how asymmetric and cooperative behaviors/traits evolve over a continuum of possible values and whether they exhibit polymorphism (using adaptive dynamics analysis) [2,10], (ii) how behavioral plasticity affects interactions and coexistence with other species [3,5], and (iii) how cooperation depends on varying survival probabilities