Systematic conservation planning for an uncertain future: An evaluation of an abiotic facet-based approach in the Columbia Plateau Ecoregion

Background/Question/Methods

Conservation planning has traditionally focused on proportional representation of regional biodiversity. However, the distribution and composition of biodiversity in a region may change in a changing climate, so biodiversity-based conservation planning may be less effective in the future. Abiotic diversity—e.g., variability in topography, soil types, and climate —can function as a surrogate for biotic diversity, and conserving the abiotic variability of a landscape may create a reserve network that is more robust to climate change. Including abiotic variability in conservation planning also reduces sampling biases inherent in biodiversity data and allows for flexibility in reserve selection subject to practitioners’ objectives. Conservation planning with abiotic facets has been suggested as a climate adaptation strategy, but has not been implemented, and tradeoffs with traditional biodiversity-based planning have not been explored.

We use Marxan, a reserve selection software, to compare conservation plans based on both abiotic facets and biodiversity targets in the Columbia Plateau ecoregion. We prioritize sites to create a portfolio of reserves that conserve the regional diversity of sets of abiotic facets; we compare these results to reserves selected with traditional biodiversity targets; and we assess tradeoffs between the two approaches.

Results/Conclusions

Correspondence analyses between clustered sets of abiotic facets and vegetation cover were highly significant (χ² ≥ 1669000, P < 0.001), indicating that abiotic facets and vegetation types were strongly correlated. However, targeting abiotic diversity instead of biotic diversity resulted in different spatial distributions of priority sites. Our biodiversity-based selection scenario consisted of targets for both vegetation types and rare species. The most efficient set of reserves based on abiotic facets represented 76% of the vegetation type targets but only 16% of the rare species targets. Thus abiotic facets were useful surrogates for vegetation types but inadequate surrogates for rare species. We recommend that conservation planners prioritize sites that are dually necessary to achieve conservation goals for both abiotic facets and current biodiversity.