Proxy Indicators Of The Value Of Diversity

This section describes a proxy indicator for the importance of a region as a primary center of diversity. With the exception of a perhaps a case study or two, figures on crop production by variety are unavailable. The probability of variety loss is unknown, as is the marginal economic value of adding (subtracting) an additional variety (to) the set of varieties that make up a species. In practice, the best one can do is to estimate a third-best proxy for the optimal allocation of the conservation funds. On a global scale, all we know is roughly where areas of high diversity are located for various species, and the best we can do is to rank regions by a proxy for the importance of their agri-biodiversity to the global agricultural economy. Doing so can provide a rough index for targeting conservation funds.

For the purpose of this chapter, and given the state of the available data, there is no reason to strongly promote any particular measure of diversity. For policymaking purposes, it is useful to divide the world into major regions of diversity, hoping to use some expert advice to assign as objectively as possible an area's relative importance to the world's major crops. Whether one follows the approaches of Vavilov, Harlan, or Zeven is not a point for this economics paper to make. The basic goal of this discussion in this section on centers of diversity is that there appears to be enough research done on the subject of centers of diversity to make a plausible case that some botanical expert(s) could make diversity assignments to the world's major regions.

Our indicator is based on the principle that plant genetic variability is not uniformly distributed throughout the world. In the 1920s, the Russian geneticist Vavilov (1926, 1949/50) noted that the level of inter- and intra-specific genetic variability varies geographically across the world. He identified the geographic areas with the highest genetic variability in cultivated food crops.

Vavilov thought that areas of maximum genetic diversity represented centers of origin and the origin of a crop could be identified by the simple process of analyzing variation patterns and plotting regions where diversity was concentrated. Although his proposed centers of origin are widely accepted even today (Harlan, 1992), his notion is somewhat simplistic and it turns out that even though many crops do exhibit centers of diversity, these centers of diversity have little to do with centers of origin (Harlan, 1992; Smith, 1995). Domesticates can, and did, originate in one region and then develop much of their diversity in another. However, while this distinction is of importance for anthropological and other reasons, it is of little practical import to the purposes of this chapter. For conservation of landraces—as opposed to wild relatives—we assume that centers of diversity are more important than centers of origin. However, centers of origin might be of importance in wild species conservation, at least in the case of species to which the concept is relevant.3 Conservation of wild varieties has a separate set of policy mechanisms from that for domesticated varieties that, by definition, require the intervention of man. Mechanisms for wild species conservation include the set-asides, nature preserves, etc., discussed in the usual context of wild species conservation.

The term "region of diversity" is currently used to refer to the variability generated by crops during their dispersal from point of origin. Thus, a plant population can be described at any point in its evolution by frequency of genes and genotypes, which illustrates its historical evolution. The regions of crop diversity are areas with high variability in number of alleles and genotypes. The genetic composition of these populations represents varying adjustments to ecological and social imperatives (Palacios). Given that these data on regions of diversity are the only relevant genetic data we have on a world scale, the best we can do is develop an indicator for the world (or OECD countries) value of agricultural production ascribed to primary regions, or centers, of diversity.

The first columns of Table 10-1 present geographic distribution of centers of diversity (FAO, 1998) derived from Zeven and de Wet on the basis of the centers identified by Vavilov. The fourth column presents the price per metric ton (in international dollars) for each commodity, and the fifth and sixth columns present the total world (and OECD) production data for each crop. The rational for the OECD figures is that if the OECD

3 Just because some regions use domesticates first cultivated elsewhere does not mean that it is low on wild ancestors' diversity. It just may mean that in that region it was more convenient to adopt varieties domesticated elsewhere than to go through the great efforts needed to breed local wild ancestors to the point where they are useful domesticates (Diamond, 1999).

countries are paying for the lion's share of this conservation effort, they may be most interested in focusing on the crops of interest to them. Given the price and quantity data, the total value of each crop is calculated. This value is then assigned to the geographic region corresponding to the center of diversity for each crop, with the total value ascribed to each center of diversity being the sum of the values of the crops for which the region is a primary center. This process produces the last column to the right in Tables 10-2 and 10-3. However, because a crop may have more than one geographic center of diversity, this measure has only an ordinal interpretation. The alternative is to normalize the measure to sum to one by dividing each instance of a primary center for a crop by the number of primary centers for that crop (i.e., for a given crop, the weight assigned to a primary center falls as the number of primary centers increases). Based on the assumption that each center provides an equal contribution as a center of diversity (which is all that can be done given the lack of data), imposing this normalization provides the measures in the last column in Tables 10-2 and 10-3 with a cardinal interpretation, and the normalized indicator, when expressed as a fraction of total agricultural value, sums to one.4

Table 10-4 ranks the regions in descending order according to their value as primary centers of diversity based on the values in Tables 10-2 and 10-3. Comparing the normalized indicator for the OECD with that for the world, we see that for the OECD, Central Asia and then West Asia rank highest as primary centers, while for the world, Southeast Asia and then South Asia are the highest. The result is due to Central and West Asia being primary centers for wheat, which is of greater importance to OECD countries than rice, while Southeast and South Asia are primary centers for rice. Not surpris-ingly too, the Mediterranean and European centers rank higher in the OECD value than they do in the overall world value. The low rankings associated with Central Africa, North America, and the Caribbean are the same for both the OECD and the world as whole. These results suggests that, with no other information being available on the general state of PRGFA, the OECD might be inclined to allocate a high share of funds to conservation efforts in higher ranked regions such as Central Asia, but if their view was more magnani-mous, they may give Southeast Asia higher consideration. In other words, if the OECD is paying for the conservation activities, they may allocate funds differently than world ranking would dictate. However, if their goals include global food security, they may well want to follow world values. Central America ranks highest in the normalized ranking primarily because it does not have to share its title as center of diversity for maize with any other region.

4 The normalization process could be more precise for the case of particular crops such as wheat and rice since certain regions are more important and data for these crops are likely to be more available than for the aggregate level I examine here.

Table 10-1. Crops, their primary centers of diversity, and international price and production


Primary centers of diversity


World production

OECD production11


E./S.E./S. Asia/W. Africa

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