Protecting biodiversity when money matters: maximizing return on investment

Abstract

Background: Conventional wisdom identifies biodiversity hotspots as priorities for conservation investment because they capture dense concentrations of species. However, density of species does not necessarily imply conservation 'efficiency'. Here we explicitly consider conservation efficiency in terms of species protected per dollar invested.

Methodology/principal findings: We apply a dynamic return on investment approach to a global biome and compare it with three alternate priority setting approaches and a random allocation of funding. After twenty years of acquiring habitat, the return on investment approach protects between 32% and 69% more species compared to the other priority setting approaches. To correct for potential inefficiencies of protecting the same species multiple times we account for the complementarity of species, protecting up to three times more distinct vertebrate species than alternate approaches.

Conclusions/significance: Incorporating costs in a return on investment framework expands priorities to include areas not traditionally highlighted as priorities based on conventional irreplaceability and vulnerability approaches.

Figure 1. Global distribution of the mediterranean biome which lies within the countries of South Africa, Chile, Australia, the United States of America, Mexico, Portugal, Spain, France, Italy, Monaco, Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Montenegro, Macedonia, Albania, Greece, Turkey, Cyprus, Malta, Syria, Lebanon, Israel, Gaza Strip, West Bank, Iraq, Jordon, Egypt, Libya, Tunisia, Algeria, Morocco and Western Sahara.

Figure 2. Comparison of the number of additional species (plants and vertebrates) protected after 20 years in the mediterranean biome using return on investment and five alternative approaches with an annual budget of $100 million per annum.

Figure 3. Comparison of species area curves for three ecoregions using total species richness data.

Curve end points represent the total area and number of species for each ecoregion, e.g., 76,449 km² and 4,387 species for MedB: Southern Anatolian montane. Factors informing the return on investment approach include; (i) the amount of ecoregion currently protected (○); (ii) available natural habitat indicated by the region between the area protected (○) and the area converted (▪), and the steepness of the curve at this point; and (iii) the cost of land (indicated by line weights). Budget allocation is based on a combination of the number of species protected and the cost of land (by multiplying the area protected by its cost per unit area to generate a species-investment curve). Low existing protection combined with the cost efficiency of protecting species prioritizes investment in the MedB: Acacia-argania dry woodlands (1). The relatively high potential returns from investing in the MedB: Southern Anatolian montane ecoregion (2) gives it a higher investment priority than the SA: Montane fynbos ecoregion (3) although the cost of conservation is double, while the latter ecoregion receives funding after 40 years. Full region and ecoregion names listed in Table 2.