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Mapping livelihoods diversity in East Africa

ResearchBlogging.orgAs the world discusses desertification and worries about the drought in East Africa, it’s as well to remember that it is livestock keepers that bear the brunt of these problems. A recent paper in Agriculture, Ecosystems and Environment helps to quantify the size of the challenge. 1

It uses environmental and livelihoods data to map the geographic distribution of different livestock-keeping strategies in East Africa. The authors — a team lead by FAO — conclude that:

…nearly 40% of all livestock in the IGAD region are kept in mixed farming areas, where they contribute to rural livelihoods in diverse ways, not least by enhancing crop production through manure and draught power and by providing additional indirect inputs to livelihoods that are seldom properly accounted for. Moreover, an estimated 50 million rural people in Eastern Africa — over a third of the rural population — live in areas where livestock predominate over crops as a source of income. Investment statistics would suggest that this fact often fails to be appreciated fully by governments, donors and policy makers.

The map itself will hopefully prove useful in guiding policy in the future, 2 but I want to concentrate here on some of the analysis that having all these data in a GIS allowed. In particular, look at graphs of the prevalence of different livelihoods strategies plotted against human population density, and then length of growing period. 3A pastoral production system is where total household income from livestock (L) is 4 or more times greater than total household income from crops (C). An agro-pastoral system has a L/C ratio of 1-4. And in a mixed farming production system the income from crops exceeds that from livestock (L/C<1).[/efn_note] fig1

fig2

It looks like areas with a human population density of 20-30 people per square kilometer and a growing season of about 150 days are the most diverse in terms of production systems. It would be interesting to know whether they are also most diverse at the species and genetic levels, for either crops or livestock. I suspect the necessary data weren’t collected in the livelihoods surveys that formed the basis of this study. Will no enterprising student go in and test the hypothesis?

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Revisiting domestication

One of the crucial pieces of evidence in studies of cereal crop domestication is the DNA mutation that keeps seeds attached to their stalk. 4 Staying attached — not shattering — is important because it allows people to harvest the seeds much more easily. You can gather bundles out in the field, carry them back to the village and do the processing there. If the seeds shatter, you have to harvest early, before they are fully ripe, and thus risk not getting their full food value or do all the processing out in the field or else risk losing much of the harvest on the way back to the village.

The loss of shattering is thus a crucial step in the process from cultivation to domestication.

The shattering mutation itself is extremely rare. In rice, for example, all types of rice share essentially the exact same mutation, crucial evidence that in rice it occurred only once, and then spread from Japonica types back into the wild and from them into the Indica types, domesticated a little later.

Now, we (and others) occasionally play the game of why aren’t any new species being domesticated. Sometimes the answer is that too many people are too satisfied with the few crop species that support humanity. Other times, it is that it is just too hard or too time-consuming, especially if one is hanging around waiting for a non-shattering mutation to arise. Mostly, both.

But hey! We know the gene that is mutated in domesticated rice, and wheat, and sorghum, and maize, and other species too, probably. And we know the nature of the mutation. And we know that the more we know, the easier it is to find out about new species. So, what if some smartypants isolated the gene from an as-yet-undomesticated species, say Coix , mutated it so it no longer functioned to shatter the seeds, and stuck it back in? 5 Then just give loads of samples to loads of farmers and let them get on with the business of selection.

Could we engineer a post-cambrian explosion of crop diversity?

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Progress in perennial wheat

We’ve always had a bit of a soft spot for perennial cereals, eagerly anticipating the day when the Land Institute’s farmer-breeders harvest ready-made muesli from their perennial polyculture on the prairies. Recent research confirms that perennial wheat is slowly coming closer in reality and simply as a concept for conservative farmers to contemplate.

As a concept, it could gain traction in Australia thanks to a desk-study that looked at the economic potential of perennial cereals there. Savings can be made in fertilisers, herbicides, tillage and sowing costs, but are they enough to offset yield penalties? Lindsay Bell and colleagues plugged a perennial wheat into a farm model called MIDAS (Model of an Integrated Dryland Agricultural System). They made various assumptions about the yield penalty that perennial wheat might labour under, the quality of the wheat, and whether it might offer grazing to livestock.

In areas where wheat is in any case not very profitable, then if the quality remains the same perennial wheat is profitable even if the yield is only 60% to 75%. If quality is lower, suitable only for feed markets, then the yield must be at least 85%. Factor in feed and things become even more interesting. On a mixed farm that raises sheep as well as wheat, a dual-purpose perennial grain that offers forage, especially early in the growing season, can “greatly increase whole-farm profitability” according to the study. Even if grain yield is only 40% of annual wheat, a perennial wheat would be worth including on 12% of the farm area. The study points out that “this demonstrates that there is capacity to trade-off grain yield for forage production from a perennial cereal”. 6

Other benefits can be factored in too. In some parts of the US, research is focused on perennial wheat because the permanent cover and particularly the root system would slow soil erosion in sensitive areas. Reports of a recent field visit at the University of Michigan, which recently won a US$1 million grant to develop perennial wheat, stress this aspect of a permanent crop. In an aside that article says that “fields could be used to graze livestock between harvests”.

I wonder whether they’re aware of this research thrust on some of the cattle ranches I’ve visited in Texas? Farmers there sow wheat only to provide forage for cattle and don’t really care whether they get a grain harvest from it or not. A half-decent perennial crop would surely be valuable for them.

There are all sorts other factors that could tip the balance in favour of perennial cereals. One that’s become especially relevant lately is carbon sequestration. Those perennial root systems are doubtless capable of plucking buckets of CO2 out of the atmosphere. It would be nice to think that maybe some of the climate change funds sloshing around might find their way into this kind of research and maybe even pay farmers to grow perennial cereals.

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Of collapse and restoration

There’s a new paper by Jared Diamond out, always a welcome event. Alas, it is behind a paywall at Nature, but it is fairly easily summarized. Drawing on recent studies of the collapse of Classic Mayan civilization in Central America and Angkor in Cambodia, and the rise of the Inka empire in the Andes, it makes two main points. One, that civilizations may collapse for multifarious reasons, but “human overexploitation of natural resources never helps.” Two, that “climate can change in either direction.” Not particularly novel or surprising conclusions, but Diamond does his usual slick job of marshaling disparate, multidisciplinary evidence from tourism hotspots all over the world and from throughout history to advance arguments of great contemporary relevance, slight whiff of environmental determinism notwithstanding.

In this case, what struck me particularly was the success story. That is, how climatic change after AD 1100, during the Northern Hemisphere’s Medieval Warm Period, may have helped the Inka’s conquests. The argument is that higher temperatures allowed them to extend agriculture to higher altitudes, increase their arable-land area and make more use of irrigation, leading to greater production and the possibility of feeding large armies. Of course, “military and administrative organization was essential to their conquests, [but] climate amelioration played a part.”

The evidence for agricultural expansion comes from the work of Alex Chepstow-Lusty and colleagues, who analyzed the pollen and other plant parts (and, indeed, other organisms) in mud cores from a high-altitude Andean lake bed. Some of the plant parts came from an alder-like tree. I had no idea that the Inka planted the nitrogen-fixing Alnus acuminata. Its remains increase in lake sediments dated from about AD 1100, along with ambient temperatures and the bodies of llama dung-eating mites, showing that there was starting to be more agriculture and livestock-keeping around the lake at that time.

The success story came to an end, of course. The Spanish cut most of alders down for fuel. Chepstow-Lusty is calling for “massive reintroduction of native tree varieties, such as the alder, to trap moisture blowing over from the Peruvian Amazon to the east. He also recommends repair of the now derelict Incan canals and terraces so they can once again support agriculture.” Have there been similar suggestions for the restoration of the agricultural infrastructure — physical and biological — of the Maya and Khmer? Maybe all the tourists could be put to work on this — or at least tapped for cash.