Delayed spending can be an optimal strategy for biodiversity conservation
Biodiversity conservation is a crisis discipline, plagued by increasing threats and chronic funding constraints. We explore the consequences of conservation organizations reacting to this state of crisis by rushing to spend money as soon as possible after they secure it. “Front-loading” of spending on conservation goals is understandably common because agencies want to address imminent threats. Rapid spending may also be driven by funding sources’ demands for demonstrable outcomes within a few years, and conservation agencies’ desire to use successful projects as justification for further funding. We demonstrate that this approach may not always be the best strategy for promoting biodiversity conservation outcomes. Here we develop a theory of conservation investment that outlines the costs and benefits of two manager options: spend now or invest to spend later. Our modelled system includes the ability of manager actions to counteract declining biodiversity decreases with time but also the potential to increase available funds if spending is delayed.
We find that waiting to spend can be the optimal strategy regardless of interest rate if funding is limited and the regional biodiversity decline does not follow instantaneously from local degradation. The optimal timing of spending represents a balance between the rate at which conservation funds appreciate in value (e.g., through interest rates), and the rates of biodiversity decline. Competing rates of biodiversity decline and potential funding increase are present in many systems, but we illustrate an application where restoration can counteract an extinction debt in forest dwelling birds. We show that with feasible interest rates, greater conservation outcome can be achieved by front-loading only a small proportion of available funds. This suggests that such benefits can justify conservation inaction under the right conditions, such as when delays allow for time to invest in capacity building or to leverage additional money.