The ecology and economics of restoration: when, what, where, and how to restore ecosystems

Restoration ecology has provided a suite of tools for accelerating the recovery of ecosystems damaged by drivers of global change. We review both the ecological and economic concepts developed in restoration ecology, and offer guidance on when, what, where, and how to restore ecosystems. For when to restore, we highlight the value of pursuing restoration early to prevent ecosystems from crossing tipping points and evaluating whether unassisted natural recovery is more cost-effective than active restoration. For what to restore, we encourage developing a restoration plan with stakeholders that will restore structural, compositional, and functional endpoints, and whose goal is a more resistant and resilient ecosystem. For where to restore, we emphasize developing restoration approaches that can address the impediment of rural poverty in the developing world and identifying and then balancing the ecosystems and regions in most need of restoration and those that are best positioned for restoration success. For the economics of how to restore ecosystems, we review the advantages and disadvantages of market-based strategies, such as environmental insurance bonds and Payment for Ecosystem Services frameworks, for funding, incentivizing, and ensuring restoration. For the ecology of how to restore ecosystems, we discuss the value of taking into account various ecological theories, site history, and landscape and aquascape perspectives, and employing a more inclusive toolbox that holistically considers alterations to propagule pressure, abiotic conditions, and biotic interactions. Finally, we draw attention to the importance of monitoring; adaptive management; stakeholder involvement; collaborations among scientists, managers, and practitioners; formal evaluation throughout the restoration process; and integrating ecological and economic concepts to maximize restoration success. We hope this overview of key ecological and economic concepts in restoration science sheds light on the discipline and facilitates restoring and maintaining the services and products provided by natural capital, thus improving human livelihoods and hope for posterity.