I came upon this interesting article this morning. The grassland ecosystem has two or more alternative states and the transitions between these states are often difficult. Grazing pressure and water condition to a large extent controls the states of vegetation. As the left figure shows, the control is non-linear. Between grazing pressure Fc and Fr, the system is in an alternative stable state. By making the system wetter, as the right figure shows, we may be able to increase Fc and Fr so the recovery will be easier. Thus the author suggested that during El Niño which brings considerable precipitation maybe we can make the system go to the high biomass state by controlling grazing. However, field experiment will be needed to determine Fr.
Will this work in Tibet? For El Niño I think the short answer is no. The longer answer: El Niño does bring increased precipitation to Tibet, but that's in winter which does not help growing of grass but decrease the next year's summer precipitation by absorbing energy that pushes rain belt up to the plateau. So in El Niño years things just go worse. But what about La Niña? Perhaps in La Niña years summer precipitation will increase so we can try the trick suggested by the author. I will seek some meteorological data from Lhasa to see if La Niña brings more precipitation in summers.
哼哼，看不懂，哼哼，打倒知识分子，我来贴大字报~~~
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