Challenges on the horizon: future scenarios and plant invasions in Aotearoa New Zealand

Large scale changes in biodiversity and conservation management require long-term goals and planning across multiple sectors in the face of increasing global change, but responses are still often short-term and fragmented across agencies and sectors. Scenario-building can be a powerful tool to imagine possible futures, integrating across sectors and disciplines and promoting long-term thinking and planning. As an interdisciplinary team of experts, we developed potential scenarios for a range of future environmental conditions. The scenarios explored: increasing land ownership and stewardship of land by indigenous peoples (Māori); widespread reforestation using native tree species; national-scale eradication of invasive mammalian predators; and increasing frequency of extreme weather events. We explored the environmental, economic, social and policy implications of these globally-relevant trends at a national scale using Aotearoa New Zealand as our study system. Each scenario presented both opportunities and risks to equality, indigenous empowerment and human capital, emphasizing the importance of good policy responses to maximize benefits and minimize unintended harm. Across scenarios several common themes were consistently highlighted, including the importance of land use in driving other conservation outcomes. How the value of ecosystem services is recognized and prioritized was also important to a wide range of outcomes.

These four non-exclusive scenarios were then used to forecast trajectories of plant invasions into natural areas by 2050 and identify research gaps and future management needs. Under each scenario we considered socio-economic and ecological drivers such as changes in land use and biotic interactions, focussing on public and private conservation areas. For a scenario considering increased land ownership or stewardship by Indigenous people, sociological research around bicultural communication was key to meet expected management needs. Under increased native reforestation, research into the impacts of landscape connectivity and long-term resilience of restoration plantings was highlighted. With non-native mammalian predator eradication, identifying the impact of species’ removal from ecological networks and plant traits that promote success will be essential to identify emerging invaders. Increases in extreme weather events will disrupt management and spread ruderal invaders, requiring the development of better decision-making and prioritization tools. Several priorities emerged across all scenarios, including the need for research and data advances, better management tools, and improved communication and consensus-building. Investment in these areas provides long-term benefits across a range of possible futures.

The four scenarios we developed have been shared with stakeholders, including policy makers and practitioners, through a combination of online workshops, conferences and publications, as well as press releases. Stakeholders have expressed interest in and support for the themes and issues raised by the scenarios, and the needs we identified through the scenario-building and analysing process. The scenarios and gaps highlighted by the work can be used to support the development of future research programmes, while the methods used to generate and analyse the scenarios have been shared so that similar exercises can be conducted elsewhere.