Category: Threats

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Uses for giant earthworms

A comment on the threat to the Banaue rice terraces prompted me to go Googling, and it seems the story has legs. Unlike the giant earthworms, which may or may not be an all-female species related to a worm called Polypheretima elongata. SciDev.net reports on the efforts of an Indian scientist, Ravindra Joshi, to help the villagers to get rid of the giant earthworms and the rats ((There’s a less informative and slightly garbled version in The Daily Telegraph.)).

To tackle the earthworms, Joshi’s team taught the Ifugao a method of ‘worm farming’ that is popular with small-scale entrepreneurs in the lowlands. The Ifugao collect the worms and rear them in a mixture of soil and old newspapers. They then harvest the worms and process them into feeds used by fish farmers.

Elsewhere in the Philippines people eat worm sausages and burgers, but the Ifugao people who built Banaue have a taboo against soil dwelling creatures. There wasn’t such a taboo against eating rats, so Joshi worked with the locals to develop a community system of rice traps that uses a particularly aromatic rice planted early as a trap crop to lure the rats to their death.

There’s another rodent, though, that eats the giant earthworms. So the villagers have learned to distinguish Rattus tanezumi from Chrotomys whiteheadi, eating the former but releasing the latter to eat the giant earthworms.

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Animal diseases reviewed

Thanks to Danny Hunter for pointing to two recent posts at CABI’s blog, one on bovine spongiform encephalopathy (mad cow disease to you and me), the other on bluetongue disease. BSE seems to be running its course and to be more or less under control, even though many mysteries still surround it. Bluetongue, however, is altogether more menacing, because it seems to have reached Britain at least partly as a result of climate change, which has allowed the midges that spread the virus to expand their range. This could be the start of something big. I don’t believe there is any resistance associated with different breeds of cattle, but I could be wrong.

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Conserving crop wild relatives

A paper just out in Biological Conservation discusses crop wild relatives (CWR) in the UK. ((Creation and use of a national inventory of crop wild relatives. Biological Conservation. In Press, Corrected Proof. Available online 27 September 2007. Nigel Maxted, Maria Scholten, Rosalind Codd and Brian Ford-Lloyd.)) The authors include some of the same British boffins who wrote a global survey of CWR conservation. The paper describes how to develop a comprehensive national plan for the conservation of CWR, using the UK as an example. Unfortunately, it is behind a paywall, but I’ll summarize the main points.

First, of course, you need to know what you’re dealing with. A UK national inventory of CWR was developed as part of the EU-funded PGR Forum project. It contains 15 families, 413 genera, 1955 species (44 endemic) — that’s 65% of the native flora. So then you have to prioritize. For example, 13 of the UK’s CWR species are considered threatened according to IUCN criteria and one is apparently extinct in the wild ( the grass Bromus interruptus). The authors ran an iterative algorithm on the distribution data for about 250 CWR species ((Chosen because of their potential economic value and perceived threat level.)) to identify the smallest number of areas which would contain the largest number of species. Seventeen 10×10 km grid squares were selected within which could be found two thirds of the priority CWR species.

To what extent are these “hotspots” already protected? Interestingly, none of them “did not overlap with existing UK protected areas.” What’s now needed is to confirm the presence of the target species in the protected areas and come up with management plans specifically aimed at the CWR.

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Quemada!

Jeremy asked recently whether shifting agriculture ((Also called slash-and-burn and swidden cultivation, and tavy in Malagasy.)) can really support growing populations. I’ve just come across (via the PLEC newsletter) a paper from Madagascar ((E. Styger, H.M. Rakotondramasy, M.J. Pfeffer, E.C.M. Fernandes and D.M. Bates 2007. Influence of slash-and-burn farming practices on fallow succession and land degradation in the rainforest region of Madagascar.  Agriculture, Ecosystems and Environment 119: 257-269.)) which says maybe.

Its objectives

were to analyze jointly with the Betsimisaraka farmers how slash-and-burn practices influence fallow species succession, and how current fallow/cropping regimes influence agricultural productivity and upland degradation dynamics.

The researchers conclude, from discussions with farmers and botanical surveys, that fallow periods have been cut by up to two thirds — to 3-5 years — in the past 30 years. This means that fallow land goes from having plentiful pigeon wood trees on it to bare, dry unproductive grassland in 5-6 rice cropping cycles, after which agriculture is no longer possible. After each cycle, the land needs to be left fallow for increasing lengths of time in order for the soil to recover fertility: “already with the third cycle after deforestation, vegetation starts to degrade quickly in parallel with agricultural productivity decline.”

The findings of this paper indicate that the tavy system with its currently short fallow periods is collapsing.

The main culprit is fire. As fallows become more herbaceous, fire is more difficult to control, and wildfires escape more easily, often “eliminating a productive plot of land for agriculture without getting any benefits of production.”

So what can be done? Try to take fire out of the equation, certainly. “The restoration of soil fertility should build on the biological potential of the system, by optimizing nutrient cycling (e.g. through residue and weed recycling, mulching) and by producing and recycling of high quality organic matter (e.g. through improved fallows and cover crops).” The key to the adoption and success of these practices will be engagement with the young, according to the authors:

The careful development of alternative agricultural practices should especially be done in collaboration with young farmers. If the young obtain a real interest in agricultural intensification, they may not feel the need anymore to leave their native villages and migrate to the forest border to undertake tavy.

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Down on the levee

A riverine trifecta today, describing threats to the biodiversity — including agrobiodiversity — associated with major rivers around the world…

From Italy, news that students and teachers from the University of Gastronomic Sciences at Pollenzo (founded in 2004 by Slow Food guru Carlo Petrini) — over 150 of them —  will travel down the Po River watershed by bicycle and boat in September and October. They’ll be giving the river and its valley a source-to-delta checkup, they say, diagnosing their ills but also identifying their abiding strengths — ecological, cultural and, presumably, agricultural.

Further east, Hubert von Goisern, an Austrian musician, has done something similar — but in his own way — for the Danube. He’s spent the summer giving a series of concerts down the river for a WWF campaign to raise awareness of the damage that planned development projects will do to the habitat of the Danube sturgeon. Plans to straighten and deepen the course of the river to facilitate shipping are expected to affect a thousand-kilometer stretch, destroying a unique natural and cultural heritage.

And further east still, Nguyen Huu Chgiem, the son of a Mekong delta rice farmer, reflects on how climate change, deforestation and saltwater intrusion are affecting Vietnam’s “rice basket.” And what he can do about it now that he’s a professor of environment and natural resources management.