Flexibility trade-offs in conservation offsets

Conservation offsets promise cost-effective conservation of biodiversity, especially under economic and environmental change, because they represent a more flexible approach to biodiversity conservation, allowing for the economic development of ecologically valuable land provided that this development is offset by restoration of previously developed areas. The level of flexibility is determined by the trading rules. Lax rules allow for more flexibility, which promises cost savings, but will likely lead to unintended loss of biodiversity. I analyzed the trade-off between economic costs and ecological benefits (biodiversity conservation) in biodiversity offsetting with an ecological-economic model that considered the three main types of offset flexibility: spatial, temporal, and ecosystem type. I sought to examine the influence of ecological and economic conditions on offset flexibility trade-offs. Large variation in the conservation costs and small costs of habitat restoration strongly increased trading activity and reduced the ecological benefit. The ecological benefit was most sensitive to spatial flexibility when a short range of ecological interaction was considered. At a large interaction range, spatial flexibility delivered large cost savings without overly reducing the ecological benefit. Risks and time lags associated with habitat restoration favored an offsetting scheme in which credits are awarded with the initiation of restoration projects rather than their successful completion-given appropriate offsetting multipliers were chosen. Altogether, under scarce resources, the level of flexibility in an offsetting scheme should be chosen by carefully balancing ecological benefits and economic costs.

Review of terrestrial temporarily conserved areas in Canada, the United States, and Mexico

The establishment of protected areas is a cornerstone of conservation, but permanent protection could be inefficient or even impossible in some situations. We synthesized the literature on temporarily conserved areas (TCAs) across Canada, the United States, and Mexico. We used a comprehensive search string to retrieve peer-reviewed articles published from 2000 to 2021 from the Web of Science. We identified 27 relevant peer-reviewed articles that examined the potential benefits of TCAs in the study area, indicating TCA is a relatively understudied area of research in the peer-reviewed literature. The TCA studies were highly clustered; 77% of studies focused on protecting a single life stage of migratory species and 61% of studies related to temporary conservation of breeding or staging habitats for migratory birds. Ninety-three percent of studies focused on preventing human-driven threats, mainly on public lands of coastal areas, the Great Plains, and the Mississippi Valley in the central United States. Short-term and experimental studies were the dominant study types. TCAs have the potential to complement permanently protected areas and provide protection when permanent protection is difficult. Some included studies examined their conservation value, but the ecological, social, and economic outcomes of TCAs are unclear. More TCA research is needed to determine the role they could play in conservation worldwide. Embracing the concept of TCAs as conservation tool could lead to more comprehensive and consistent reporting of the outcomes of temporary area-based conservation measures. However, a global review and analysis of effectiveness of TCAs will be required if they are to play a formal role in meeting international targets for biodiversity conservation.

An economic evaluation framework for land-use-based conservation policy instruments in a changing climate

Climate change is a key threat to biodiversity. To conserve species under climate change, ecologists and conservation scientists suggest 2 main conservation strategies regarding land use: supporting species' range shifts to enable it to follow its climatic requirements by creating migration pathways, such as corridors and stepping stones, and conserving climate refugia (i.e., existing habitat areas that are somewhat buffered from climate change). The policy instruments that could be used to implement these conservation strategies have yet to be evaluated comprehensively from an economic perspective. The economic analyses of environmental policy instruments are often based on ecological effectiveness and cost-effectiveness criteria. We adapted these general criteria to evaluate policy instruments for species' conservation under climate change and applied them to a conceptual analysis of land purchases, offsets, and conservation payments. Depending on whether the strategy supporting species' range shifts or conserving climate refugia is selected, the evaluation of the policy instruments differed substantially. For example, to ensure ecological effectiveness, habitat persistence over time was especially important for climate refugia and was best achieved by a land-purchase policy instrument. In contrast, for the strategy supporting range shifts to be ecologically effective, a high degree of flexibility in the location of conserved sites was required to ensure that new habitat sites can be created in the species' new range. Offset programs were best suited for that because the location of conservation sites can be chosen comparatively freely and may also be adapted over time.