Of some good also

El Nio can help recover degraded land

Last Updated: Saturday 04 July 2015

'El nio' could have a benevolent side to it also. Netherlands-based researchers say it could be harnessed to recover land that has been degraded by overgrazing and desertification.

Marten Scheffer and Milena Holmgren, ecologists at Wageningen University, Netherlands, say some arid areas are so badly degraded that they cannot recover by themselves, even when grazing animals are removed. But coinciding this with El Nio's arrival, which occurs once every three to six years and leads to a dramatic increase in rainfall in some normally dry regions, could provide the impetus to make these areas fertile again. Landowners could harness the power of El Nio to shock their lands into recovery.

Mohan Wali of Ohio State University in Columbus, usa , says the idea is good in theory, but he's not sure how it would work in practice. One problem is that El Nio is unpredictable. "One may only get a few weeks' warning. What could you do in that time? We are talking about vast areas of land," he says.

But Scheffer and Holmgren point out that many ecosystems can be stable under a number of different sets of ecological conditions. Each such state, such as woody, herbaceous or bare soil, is relatively stable and can withstand fluctuations in the weather. But a dramatic shift in environmental conditions, such as the amount of grazing or rainfall, can push each system over a threshold into a different state, where it remains even if ecological conditions return to what they were before. El Nio could give the much-needed push for the land to jump over this threshold claim, the researchers. Landowners could harness the power of El Nio to shock their lands into recovery.

If farmers stopped grazing for just one season during El Nio the combined effect of increased rainfall and reduced grazing could be convert the land into a new, stable, recovered state.

The researchers are testing their ideas on arid lands in Chile. "We want to know whether El Nio has facilitated recovery of the forest in the region," says Scheffer. They will check tree rings to see how the climate has changed and test plots of land with and without herbivores and water, to try to pinpoint what are the critical thresholds.

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