Reallocating budgets among ongoing and emerging conservation projects.

Conserving biodiversity and combating ecological hazards require cost-effective allocation of limited resources among potential management projects. Project priorities, however, can be both stochastic and dynamic over time as underlying social-ecological systems progress, novel priorities emerge, and management capabilities evolve. Thus, reallocation of ongoing investments in response to shifting priorities could improve management outcomes and address urgent demands, especially where additional funding is not available immediately. Resource reallocation, however, could incur transaction costs, require additional monitoring and reassessment, and be constrained by ongoing project commitments. Such complexities may prevent managers from considering potentially beneficial reallocation strategies, reducing long-term effectiveness. We propose an iterative project prioritization approach based on marginal return-on-investment estimation and portfolio optimization which guides resource reallocation among ongoing and new projects. Using simulation experiments within two case studies, we explore how this approach can improve efficacy under varying reallocation constraints, frequencies, costs, and rates of project portfolio change. We found that periodic budget reallocation could enhance the management of stochastically emerging invasive weeds in Australia, reducing the overall risk by up to 50% compared to a static budget. Reallocation frequency and the rate of new weed incursion synergistically increase the conservation gains achieved by allowing unconstrained reallocation. Conversely, budget reallocation would not improve the IUCN conservation status of threatened Australian birds due to slow rates of transition among conservation states, and might increase extinction risk if portfolio reassessment is costly. While other project prioritisation studies may recommend periodic reassessment and reallocation, our findings reveal conditions when reallocation is valuable, and demonstrate a structured approach that helps conservation agencies schedule and implement iterative budget allocation decisions cost-effectively. Article Impact Statement: Reallocating funding among conservation projects in response to shifting or emerging priorities may improve outcomes. This article is protected by copyright. All rights reserved.