The impact of wilding trees on indigenous biodiversity: a choice modelling study

Abstract

Invasive species are typically non-indigenous species that adversely affect the habitat they invade. The adverse impact can be ecological (e.g. extinction of indigenous species), environmental (e.g. altering ecosystem function) and/or economic (e.g. reducing tourism). Wilding trees are invasive species that threaten large areas of the South Island high country. Once mature, most conifers are prolific producers of seed, whose spread, aided by wind, can cover large areas. Within a given location a wide range of values will attach to the services flowing from the South Island high country ecosystem. These values can be broadly described as use values and existence values. Examples of use value include recreation and grazing. Existence values may arise from knowing that the habitat for endangered indigenous species is being preserved. Estimates of these values provide information to decision makers charged with allocating scarce funds for biodiversity conservation. This paper reports on the application of a choice experiment to estimate community preferences and values associated with the impact of wilding pines on indigenous species in the South Island. Defining the South Island high country as natural capital comprising inter alia an ecological system provides a conceptual link between the incursion of wilding trees and changes in the flow of services associated with the ecosystem. Economic valuation focuses on changes in utility associated with changes in the flow of services from the natural environment. In the case of wilding trees the aim is to measure the change in utility that attaches to changes in indigenous biodiversity.