Safeguarding iconic tree species, dependent ecosystems, and regional economies: A New Zealand perspective on controlling Kauri Dieback

In response to a disease outbreak affecting an iconic ecosystem, restricting recreational access emerges as a crucial strategy to control disease spread, despite significant social and economic impacts. The study examines the economic implications of Kauri Dieback, affecting the emblematic kauri trees located in the Waitākere Ranges Park in New Zealand, on the local, regional, and national economy through impacted recreational services. Using a risk-assessment framework integrating components of a probabilistic Cost-Benefit-Analysis (CBA), we investigate the impact of a Kauri Dieback outbreak on recreation and related spending. We assess costs based on protection management plans and expected benefits by considering the avoided economic losses from a probable park closure. Our research introduces a novel element by calculating the minimum probability of a park closure that would make protection measures cost effective. These probability thresholds can then be compared with the expert-elicited probabilities of a park closure to economically justify protection measures. A sensitivity analysis examines key assumptions, including the consideration of the indirect and induced impacts from a potential outbreak using economic multipliers. Findings show a low threshold probability range (0.2–8.9 %) for cost-effective interventions under different plausible scenarios. The scenario considering a high expenditure per visitor yields the highest net benefit (NZ$5 billion for a one-year closure), while the lowest net benefit (NZ$76 million for a one-year closure) is associated with the lowest counterpart. It underscores the need for strategic investments to protect kauri trees in a complex economic context, providing valuable insights for policymakers and the community.