Deforestation during the Roman period

• 1. A Pristine Planet

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  Deforestation during the Roman period began on a planet that, 8,000 years earlier, supported only a few million people and was still fundamentally pristine. Then came Rome. Its empire grew across the Mediterranean with a larger population, farming on a vast scale and an economy unlike anything before it. Rome drove human development in Western Europe, and it became a leading contributor to the loss of forests around the Mediterranean. This documentary follows the trees. Where did the timber go, and what did the missing forests do to hillsides, rivers and harbours? Did the Romans understand what they were doing? And did the loss of woodland help bring the empire down, or have historians overstated the damage altogether?

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• 2. Roofs and Furnaces

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  One estimate puts the empire's population at 56.8 million people, and other estimates reach as high as 70 million. All of them needed shelter, and the most basic building supply of the age was wood. Some Mediterranean houses were built of brick and stone. Even so, roof structures beneath their tiles were often timber, and so were the floors of multistory apartment buildings.

  Rome alone may have held a million people or more. Europe would not see a city of that size again until London in the 19th century.

  Wood was also the fuel of industry. Mining, smelting and the firing of ceramics all depended on it. Smelters that burned wood sent heavy metals into the air, and burning fuelwood filled the sky with pollution.

  Urban growth around Rome began where natural resources were easiest to reach. Lowland areas and sites near water transport were the first to fill up. Overcrowding later pushed citizens onto the hillsides, where forests had once stood, to build their homes. As population, trade and manufacturing kept rising, the empire turned to expansion and the colonization of conquered lands to find more resources.

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• 3. Fields and Flocks

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  In 111 BC, Roman law allowed anyone who occupied up to 20 acres of public land to keep it, provided the land was brought into cultivation. A policy like that encouraged widespread clearing. It also shows how much agriculture mattered, since it was the economic base of the empire and served the wealthy, ordinary citizens, the military and merchants trading with other regions.

  Tools changed the work. Iron ploughs and harvesting machines took over from human hands, and animals were used to clear dense forest so that farmers could reach the rich topsoil beneath.

  Guy Theodore Wrench wrote about the result in a book whose fifth chapter is titled Roman Soil Erosion. He describes the devastating effects of widespread clearing, followed by the overworking of land to grow ever more grain for a booming population.

  Domestic animals added to the damage. Herds grazed on land that was unsuitable for crops, eating hillside plants and young trees before they could grow. Soil washed away from the slopes, and in the worst cases the bare rock beneath was left exposed.

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• 4. Legions and Fleets

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  Julius Caesar himself ordered his troops to cut down forests so that enemies could not use them for cover in a sneak attack. Roman legions followed the same logic wherever they camped or marched. The standing army numbered about 300,000 and grew to 600,000 toward the late Empire. Soldiers also used timber to build fortresses, tools and the transport that carried their supplies.

  Campaigns devastated the countryside, and some farmers were forced to fight rather than tend their land. When resources ran low in territory Rome already held, the army was sent out to defend it. It was also sent to take regions where timber was plentiful, to feed the needs of the Roman economy.

  Shipbuilding was a major drain of its own. Thousands of ships were built during the classical period, and in wartime hundreds could be completed within a month. Shipyards stripped the timber from their own surroundings. After that, wood had to be carried in from elsewhere. That was expensive, but a growing fleet was needed to hold naval dominance.

  Sea power was vital to political control, so warships had priority over merchant vessels when materials were scarce.

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• 5. Silt and Floods

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  By the 3rd century, erosion had accelerated up to twentyfold. Years of clearing and plowing had worn out the soil until it became infertile. Mediterranean weather and hundreds of years of harvesting cut yields further. With no forest or litter layer to protect the ground, rain ran off quickly instead of soaking in.

  The runoff carried silt that clogged the channels bringing water to farmland. It also created unusable marshlands, which spread diseases such as malaria, and it disturbed the water supply to natural springs and rivers.

  Coastlines changed. Around the mouths of the Po River, the sea edge was pushed many miles farther out. Silt and gravel buried harbours at river deltas, and ports had to be relocated, which placed a further burden on the economy.

  Rome itself was not spared. Floods covered the lower parts of the city and backed up its sewers. The first such flood was recorded in 241 BC, and the records show the river flooding more often from then on.

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• 6. Did Rome Notice

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  In the 5th century BC, the philosopher Plato complained that "the loss of timber had denuded the hills and plains surrounding Athens and caused massive soil erosion." Awareness of the problem, then, was not unknown in the ancient world.

  Roman voices sound less worried. Cicero wrote, "we (humans) are the masters of what the earth produces," and added that "all things in this world which men employ have been created and provided for the sake of men."

  Historians still debate how far the Romans grasped the consequences. Clearing land for crops and for heat was necessary for long-term survival. Richard Grove offered a rule of thumb: "states will act to prevent environmental degradation only when their economic interests are shown to be directly threatened."

  Rome did practice some conservation. Glassware was recycled, and buildings were designed to take advantage of solar heating. Forests were subject to government regulation and protected as a resource for the future.

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• 7. Collapse Theories

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  The scholar Tainter argued that "deforestation did not cause the Roman collapse." He allowed, though, that a case could be made for it as one part of the story. Williams thought it more likely that constant war, epidemics, rebellion, invasion, a declining population and excessive urbanization were responsible, alone or together. Each of them pressed on the land of an empire stretched beyond its means.

  In his 2011 environmental book Life Without Oil, Steve Hallett proposes a different link. He suggests that the Mediterranean reached a peak wood scenario. As timber had to be hauled from farther away, diminishing returns undermined the economic performance of Roman industry. That left Rome exposed to invasion and internal division, which are well documented problems.

  Hallett offers this as a cautionary tale, comparing it with the possible fate of modern society after the world's peak oil.

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• 8. The Revisionist Challenge

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  The environmental historian J. Donald Hughes, who lived from 1932 to 2019, studied ancient Mediterranean deforestation from 1975 onward. In 2011 he wrote that scholars from the mid-nineteenth century through the first three quarters of the twentieth had agreed that human activity had depleted forests and caused severe erosion. His own research confirmed that picture. Since then, revisionist historians have argued that little environmental damage was done.

  Hughes pointed to The Corrupting Sea, a 2000 study by Peregrine Horden and Nicholas Purcell, as a milder challenge. They admit that overgrazing and mining destroyed some forest. In their view, though, such damage was rare and localized, and clearing was seen as a "Good Thing" because it improved land for farming.

  A.T. Grove and Oliver Rackham, in 2001 and 2003, were more skeptical. They argued that most conclusions about severe erosion in the Roman Mediterranean projected present concerns onto the past. Time, place, climate, geology and topography vary so much, and the evidence is so fragmentary, that generalizing is almost impossible. Hughes called their stance revisionist and said they reversed the burden of proof.

  Their case has specific points. Dates, figs, olives and chestnuts were important crops, and grain was often grown among them. Almost all tree species regrow when cut, and coppicing is one way to harvest wood sustainably. Roman hypocausts, the underfloor heating systems, could burn straw and coal, and coal was abundant in many parts of Roman Britain.

  Some erosion blamed on Rome may date to the Dark Ages, when terraces that protected hillsides were no longer maintained. Changes in tree cover may come from climate, and there is some evidence linking the decline of the Roman West to climate change. Slash-and-burn farming, practiced by smaller populations, can cause as much erosion as Roman agriculture. Coastal marshes can come from sea level changes as easily as from soil erosion.

  One last clue reaches far behind Rome. Tree diseases as early as 6,000 years ago may have caused the elm decline, and that decline may be tied in some complex way to Neolithic farmers.

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