Conservation futures 2050: Developing future scenarios to explore potential socio-economic developments and their impact on biodiversity

species [45]. This scenario assumes that commercial forestry and amenity plantings are con- verted to use exclusively native species and strategic areas like riparian zones and steep slopes are reforested in native plantings for ecosystem services and/or biodiversity credits (perma- nent forest). This results in significant increases in forest cover with the potential to reverse the decline of native biodiversity, particularly for deliberately planted species. Non-native mam- malian herbivore control, restoration of lowland areas and increased connectivity improves resilience of native ecosystems, as does the reduction in propagule pressure for potentially invasive non-native trees [46–48]. However, environmental risks include decreased resilience of tree cover because of transitions and slower tree growth rates and abandonment of non- native production forests. Perverse outcomes could occur if production values conflict with conservation values for native species, for example through a loss of effective genetic diversity for commercially grown native trees. This scenario creates opportunities for policy incentives, such as credits for biodiversity or ecosystem services, strategic tax relief, or practical support to promote managing land for biodiversity and ecosystem services across a broader scale. Such a dramatic transition inherently risks unintended policy consequences and the potential for neg- ative effects on the ability to meet international trade and carbon reduction agreements in the short- to medium-term [49].

The transition away from current non-native forestry practices risks significant economic disruption, with a loss of jobs, drop in export volume and value, and high research and devel- opment costs before any new economic return is generated [50]. Credits and other monetary incentives would become an increasingly important component of the national economy, but this risks high exposure to the volatility of such markets. If the transition results in mass job loss and displacement in rural and forestry-dependent communities, this would likely exacer- bate inequalities, limit opportunities and increase disaffection. However, if the transition incorporates Māori knowledge and cultural practices, it could improve Māori wellbeing and generate positive social effects from an increased sense of place for all residents [43, 51]. Eco- nomic opportunities could develop around creating local and international markets for native plant commodities [52], with the increase in research and development necessary to establish new production forests and markets. Predator eradication Under this scenario, rats (three Rattus spp.), mustelids (three Mustela spp.) and brushtail pos- sums (Trichosurus vulpecula) are functionally suppressed or eliminated nationally [53], and by 2050 funding and operations are shifting to border security and local maintenance. Predator control is expected to increase the population size and range of many native bird species, but should also benefit non-native birds and may result in meso-predator release for uncontrolled

non-native predator and herbivore species [54, 55]. Increasing bird populations and a reduc- tion in rodent seed predation will benefit bird-pollinated and bird-dispersed native species, but could also increase invasive plant populations, for example through increased dispersal by birds [56]. Policy opportunities include pioneering management and legislative frameworks to focus on whole-ecosystem regeneration and robust biosecurity and predator eradication. However, later stages of eradication will require major efforts or new technologies to detect and eliminate species at low population densities, potentially leading to controversial or dam- aging changes to norms and legal rights around private property and unintended harm to non-target species [55]. Significant economic risks stem from the high cost of achieving and maintaining suppression or eradication of target species at large spatial scales. Delayed invest- ment in other sectors as a result of high investment to achieve predator-free status can also result in cascading costs in those neglected sectors [23]. However, once suppression or PLOS ONE Conservation futures 2050 PLOS ONE | https://doi.org/10.1371/journal.pone.0311361 December 12, 2024 7 / 16