The Value of Controlling Wilding Conifers in New Zealand

ABSTRACT

Exotic, invasive conifer tree species, known as ‘wilding conifers’, pose a significant threat to natural ecosystems and are costly to manage, creating a need to identify community preferences in order to inform and balance public investment in their control. Currently, approximately 7% of New Zealand's total land area is covered by invasive wilding conifers, and the rate of spread is approximately 5% per year. This study analysed the preferences of the New Zealand population regarding the control of wilding conifers in indigenous ecosystems using a choice experiment. The results, obtained through a mixed logistic model in willingness‐to‐pay space, showed that the public places significant value on controlling the spread of wilding conifers. Preferences for control displayed distance decay and diminishing marginal utility. The study also examined the spatial heterogeneity of preferences in terms of distance decay and the spatial dimension of scope. Finally, the study estimated the value of controlling the spread of wilding conifers nationally, which was found to be about NZ$147 million annually, and broadly consistent with the economic damage caused by other major invasive weeds in New Zealand. These findings confirm the importance of spatial factors in explaining preferences for the control of invasive trees and demonstrate how policymakers can use the estimated values to measure the benefits of different control options.