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What is the value of pollinators?

Exactly a year ago yesterday Jeremy wrote a post about the dollar value of pollination as an ecosystem service. Now comes an article in Gaia which argues that previous criticism of such valuations in the same journal are unfounded. 1 A year is a long time in science.

The criticism in question was based on the observation that “crops depend on pollinators but crop yield does not necessarily depend on pollinators as other factors are likely to limit crop production.” Jaboury Ghazoul called this the “pollination paradox” 2 in an article which argued that it is impossible to value ecosystem services individually.

The authors of the latest paper dissect the situation with coffee and almond and conclude that “there is currently no evidence for a pollination paradox.” However, they do say that recent figures for the monetary value of pollination may well be media-driven overestimates. Even the often-seen figure that “one third of the caloric value of our food is derived from animal pollination … is still not well supported.” That pollinators are important to food production is not contested. But how important is perhaps not as easy to calculate as has been made out.

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Meta-analyzing diversity

If you’ve just arrived from Tangled Bank, welcome. And be aware that there’s a follow-up post.

A couple of meta-analyses on the menu today.

ResearchBlogging.org Devra Jarvis and Bioversity International colleagues, together with numerous co-authors from national programmes around the world, have a paper in PNAS summarizing the results of a 10-year effort to establish the scientific bases of on-farm conservation of agrobiodiversity. 3

Varietal diversity 4 data on 27 crops grown on 64,000 ha by 2,041 households in 26 communities in 8 countries on 5 continents were pulled together in a stunning feat of synthesis. Are any generalizations possible from such a massive dataset? Well, perhaps surprisingly, yes. Let me pick out the highlights:

  1. Households growing traditional varieties generally grow more than one (1.38-4.25).
  2. Households within a community tend to grow somewhat different sets of traditional varieties.
  3. Larger fields generally have more traditional varieties, but smaller fields tend to be more different in varietal composition.

There’s much more to this rich analysis than that, but the take-home message can be pretty easily stated: crop genetic diversity can still be found on-farm because even neighbouring families choose to grow different traditional varieties, and generally more than one. Especially families tending smaller fields, who will presumably be poorer and living in more marginal conditions. The conoscenti will recognize a familiar meta-narrative, but it is good to have solid data from a wide range of crops and from all over the world.

The next paper I want to talk about looked at genetic diversity in wild clonal species as it relates to their breeding system. 5

Summarizing 72 genetic diversity studies, including of a couple of crop relatives, the authors found that populations of self-incompatible clonal species tended to have fewer genotypes, more unequally distributed (i.e., with a few dominant clones), than populations of self-compatible clonal species. It would be interesting to see if this relationship is also present in vegetatively propagated crops. I don’t think the previous dataset would help with that, however. Only two clonal crops were included in the on-farm analysis, cassava and taro. Interestingly, they had the highest average levels of community-level varietal richness (33) compared to seed-propagated species.

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Yams in New Caledonia

Danny has just sent me this great old postcard from New Caledonia: “Preparations for a family celebration.” You can see how central yams are to Kanak culture. In 2004 the Kanak Traditional Senate established a Conservatoire de l’Igname. I never visited it, but I saw photos of it when a couple of the people responsible, including a senator, came to our regional plant genetic resources network meeting in Fiji a couple of years ago, and it looked great. Unfortunately, it doesn’t seem to have much of an online presence.  Yet.

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Classifying conservation actions

An article in PLoS Biology recently suggested that IUCN should change the classification system it uses for protected areas (PAs). 6 Currently reflecting management intent (e.g. “National Park: managed mainly for ecosystem protection and recreation”), the idea would be for the new categories to rather “be based on the quality and quantity of the contribution of each PA to conservation of biodiversity (and associated sociocultural values).” So: actual result, rather than intent; and “what ” and “how much” rather than “how.” Seems like a pretty good idea. And it also seems like the concept could be applied not just to protected areas, but to conservation actions in general. That would spell the doom of the tired old in situ/ex situ dichotomy. Not a minute too soon, as far as I’m concerned.

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Momi-2008

The latest of Mitsuaki Tanabe’s monuments to wild rice was unveiled in the FAO building in Rome yesterday. Tanabe has donated this sculpture to the Global Crop Diversity Trust, and it is now installed by a window just in front of the Trust’s offices. Representing a seed of Oryza meridionalis, which is found in northern Australia, “Momi-2008” is about 9 m long and about 250 kg in weight. It took 20 men to get it up the stairs. This photo doesn’t really do it justice.

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