Friday, July 11, 2008

Global mapping of ecosystem services and conservation priorities

A new PNAS paper. It doesn't seem to be online yet and here is the citation.

Naidoo, R., A. Balmford, R. Costanza, B. Fisher, R. E. Green, B. Lehner, T. R. Malcom, and T. H. Rickets. 2008. Global mapping of ecosystem services and conservation priorities. Proceedings of the National Academy of Sciences. 105:9495-9500

Back in 2006 I was in WWF sitting on a meeting with these authors to work on this paper. Great to see it finally came out. The two biggest changes they made ever since then are:

1. They still thought about using monetary values of ecosystem services. For the two carbon-related services it was easy. But it was tricky to value grassland production of livestock and water provision service. A production based method was proposed to value the former and the trickiest is the water provision service.

2. They used a study done at finer scale to calibrate their result (Chan et al 2006, citation 26, figure above), which definitely is a great move.

This figure pretty much summarizes the whole paper in my opinion. First, to understand the figure: Quardrant 4 is the win-win areas, and quadrant 3 and quadrant 1 are the areas that either biodiversity or ecoservices are conserved. Serveral conclusions can be drawn from this figure:

1) The datapoints are pretty much evenly distributed across the four quadrants, which means there is no concordance among biodiversity and eocsystem services conservation at the global scale. At least when number of endemic vertebrate species and carbon storage were used as surrogate.

2) The result from Chan et al's fell into the "right" quadrant, so the result from this paper has some validity by this rough calibration exercise. "Some validity" is a compliment though it may not sound like one. I was there and I know every step forward at the global scale is not easy.

3) Global scale perhaps is an optimal scale for mapping exercises but probably is not optimal for investigate the concordance question that everybody is mostly interested in. As the authors acknowledged, "even win-win ecoregions can contain areas that reporesent trade-offs between conservation and ecosystem services (pg 9498)." Another paper (CI's effort) that asked the same question drew the same conclusion in fact, in spite of a very different methodology used (Turner et al. 2007. Global conservation of biodiversity and ecosystem services, BioScience 57 (10)).

HT: Bob Costanza via GIEE list.

No comments: