Forests Precede Civilizations and Deserts Follow Them

Around 2000 BCE the farmers of southern Mesopotamia began to replace wheat with barley in their fields, and the records they left suggest why. Irrigation had been drawing salt up through the soil of the world's first great cities, and wheat, which tolerates salt poorly, was failing. Within a few centuries the yields that had fed Sumer were gone, and the centre of power moved north. A line credited to the French writer Chateaubriand puts the pattern in a few words, that forests precede civilizations and deserts follow them. It claims that every society begins in the green abundance of nature and ends, if it is careless, in sand.

The oldest witness is Plato. In the dialogue Critias he describes the hills of Attica as they once were, covered with tall trees and fed by springs, and contrasts them with the bare rock that remained in his own day. Rich soil, he says, had washed away into the sea, leaving the land like the skeleton of a body wasted by disease. The cedars of Lebanon, which supplied the temples and fleets of Egypt, Phoenicia and Israel, were cut so heavily that only a few groves survive. Timber was the oil of the ancient world, and the societies that wanted ships and furnaces drew heavily on it.

Forests do more than supply wood. They hold soil against rain, release moisture into the air and keep rivers running through the dry season. When they are removed, the effects spread beyond the clearing. In the American Great Plains the deep rooted prairie grass was ploughed under in the early twentieth century to grow wheat, and when drought arrived in the 1930s the exposed topsoil rose in great storms that darkened the sky as far as Washington. Hundreds of thousands left the plains, and the Dust Bowl became a lasting image of what an economy built on bare soil can do.

The story of Easter Island has often been told as the perfect example, with islanders who cut down their palms to move statues and then starved among the ruins. Recent studies have complicated it, pointing to rats that ate the seeds, to disease brought by European visitors and to a population that was more resourceful than the legend suggests. The caution is useful. The link between forest loss and collapse is real, but it is seldom the whole explanation, and storytellers should avoid fitting a neat moral to messy evidence.

Timber was the oil of the ancient world, and the societies that wanted ships and furnaces drew heavily on it.

India has its own lessons. In March 1974 women in the village of Reni in the Himalayan foothills of Uttarakhand, led by Gaura Devi, stood between the axemen and the trees, embracing the trunks, and the Chipko movement, which had begun a year earlier, forced the state to rethink its logging policy. Their argument was practical and not sentimental. Forests gave them fodder, fuel and water, and floods followed felling. The Forest Conservation Act of 1980 grew partly out of this pressure, and it showed that those who live nearest to the trees often understand the cost of losing them better than distant planners.

Ancient Indian texts recognised the value of woodland as well. Kautilya's Arthashastra prescribes protected forests for timber and for elephants under royal officers and lays penalties on those who cut trees without leave, and Ashoka's edicts forbade the burning of forests without cause. The state in these accounts treated woodland as a resource of strategic value, needed for war and for building, and not simply as wasteland waiting for the plough.

Yet the line is not a law of nature, and history offers counterexamples. The Sahara itself was green with lakes and grassland about six thousand years ago, and shifts in the earth's orbit turned it to desert long before any city rose beside it, which is a reminder that deserts have natural causes too. Europe and the United States cleared much of their original forests and became rich, and today both have more woodland than they did a century ago. Economists and geographers call this the forest transition. As farming becomes more productive and populations move to cities, marginal land is abandoned and trees return. Costa Rica, which lost much of its cover by the 1980s, has restored more than half of its territory to forest through payments to landowners for keeping trees standing. The desert does not always follow.

The qualification matters for policy. If forest loss were an inevitable first step of progress, poor countries might be told to clear now and repair later. If the damage is a debt that compounds, they should be helped to avoid it. China's work on the Loess Plateau, where terraces and tree planting restored degraded land that had been among the most eroded on earth and lifted the incomes of farmers, suggests that repair is possible but slow and expensive. The Sahel's Great Green Wall has had mixed results, which shows that planting without local ownership often fails.

Seen in this way, the line is best read as a statement about dependence. Civilization draws on a living capital that renews only at a certain pace, and it prospers as long as it spends the interest and not the principal. Cities that ignore the watershed supplying them, farms that mine the water beneath them and economies that count the felling of a forest as income and not as loss are all borrowing against a future they will not be able to repay. Natural capital needs the same accounting as money, and governments are only beginning to keep such books.

A last doubt remains about the comfort of the forest transition. The countries that have regained woodland have often done so partly by importing timber, soy and beef from forests elsewhere, which means that a green hillside at home may rest on a cleared one abroad. If so, the rich world's recovery has been paid for by someone else's desert. It is not clear whether any civilization has yet reached the end of the sequence without sending its deserts somewhere else, and the line, written in the age of the axe, cannot say whether the planet as a whole has anywhere left to send them.