09 April 2012

How should we prioritize conservation action globally?

Warning: technical material ahead...

Driven by the agreement set by the signatories to the Convention on Biological Diversity to “significantly reduce the rate of biodiversity loss by 2010 (Jones et a 2011),” conservation prioritization became a hot topic. In light of recent indications that the rate of biodiversity loss has not declined and pressure on areas of high diversity has increased (Butchart et al. 2010), this continues to be a pressing issue. Here I review a piece from 2006 by Brooks et al. entitled "Global Biodiversity Conservation Priorities" which tries to sort out the most effective way of prioritizing conservation ahead of the 2010 assessment, and apply the lessons to what we see in Madagascar today.

Brooks et al (2006) looked at prioritization schemes set by major conservation NGOs and classified them based on axes of irreplaceability and vulnerability. Irreplaceability is usually indicated by levels of endemism, but can include taxonomic uniqueness  and rarity of habitat types but these are hard to quantify. Richness is not of primary concern because “species richness is driven by common, widespread species; thus, strategies focused on species richness tend to miss exactly those features most in need of conservation (Brooks et al 2010).” Vulnerability is not clearly defined here but is a temporal indicator of threat. The most commonly used indicators are proportional habitat loss and protected area coverage. The authors bemoan the lack of consideration of demographic change, pressure from hunting, governance and institutional weaknesses and (which I found hugely surprising that it wasn't present) cost.

There is also a spatial component to these schemes and they all use overlapping “ecoregions” to define funding rather than a grid-based system. This has substantial effects on prioritization and the authors suggest normalizing these ecoregions because they are biased towards larger ones. Grid-based methods, however, like that used by Kremen et al (2008) to prioritize nationally in Madagascar, should supersede this concern.

By mapping the 9 most common prioritization schemes the authors were able to find high overlap within two groups of strategies, proactive and reactive, but not across them. Both proactive and reactive strategies prioritize high irreplaceability but reactive strategies also prioritize those with high vulnerability because these are the sites where action is most urgently needed while the proactive strategies prioritize low vulnerability because this is where conservation is most easily done(less politically charged and often cheaper).

The authors judge the success of the prioritization based on how much of the flexible funding available for conservation it was able to capture – the wrong measure. Shouldn’t we judge success on conservation outcomes? If we are going to focus on finances we should be looking at cost-effectiveness, which isn't included at all here, rather than funds captured. This data is becoming more readily available and will be a factor of future prioritizations so as that data is incorporated, this is likely to change. There are also political reasons why this is the wrong measure – CI appears to be moving away from the Hot Spot approach (or so says Kareiva, the head of The Nature Conservancy), lauded here for garnering the largest share of the pie, and turning to a people-centered ecosystem service approach to prioritizing funding. If the "success" of these priorities are so transient they are not useful in making future prioritizations. 

Most of Madagascar, especially the highly diverse moist forests, is prioritized by most of the reactive schemes, while the dry deciduous forests of the west are also prioritized under proactive schemes that look for areas of low threat. The overlap here demonstrates the need to more deeply investigate the level of vulnerability of this ecosystem.

Corridor Ankeniheny-Zahamena (CAZ) illuminates some of the complexity of prioritization. Madagascar itself was identified under the Hot Spot approach by Conservation International, a reactive scheme, but the particular site, an approximately 400,000ha area of contiguous forest, was selected based on irreplaceability and low vulnerability (ie it was an easy area to protect because of low human populations in the forest interior). Now, an ecosystem-service narrative, rather than a biodiversity one drives continued funding and discourse around CAZ. This shows the differences of scale and discourse in prioritization, which aren’t captured by an assessment of global schemes.

While there may be overlap between biodiversity priorities and ecosystem service priorities in terms of carbon and water quality, they by no means must overlap and we need to be clear about what it is that we are prioritizing. As of now, while we are shifting toward a commodity view of how to protect areas, there is far too often a lack of clarity. In fact, we still don’t have a strong understanding of the relationship between biodiversity and specific ecosystem services. This muddiness and ambiguity is yearning for clarity.

Brooks, T. M., Mittermeier, R. A., da Fonseca, G. A. B., Gerlach, J., Hoffmann, M., Lamoreux, J. F., Mittermeier, C. G., et al. (2006). Global Biodiversity Conservation Priorities. Science313(7 July 2006), 58-61.
Butchart, S. H. M., Walpole, M., Collen, B., van Strien, A., Scharlemann, J. P. W., Almond, R. E. a, Baillie, J. E. M., et al. (2010). Global biodiversity: indicators of recent declines. Science (New York, N.Y.)328(5982), 1164-8. doi:10.1126/science.1187512

Jones, J. P. G., Collen, B., Atkinson, G., Baxter, P. W. J., Bubb, P., Illian, J. B., Katzner, T. E., et al. (2011). The why, what, and how of global biodiversity indicators beyond the 2010 target. Conservation biology : the journal of the Society for Conservation Biology, 25(3), 450-7. doi:10.1111/j.1523-1739.2010.01605.x
Kremen, C., Cameron, A., Moilanen, A., Phillips, S. J., Thomas, C. D., Beentje, H., Dransfield, J., et al. (2008). Aligning Conservation Priorities Across Taxa in Madagascar with High-Resolution Planning Tools. Science, 320(222), 222-226. doi:10.1126/science.1155193