Michael Williams continues our series on History and the Environment by considering how long humans have been making ever-growing inroads into forests.
IT IS A COMMON misconception that deforestation is a recent occurrence, gaining momentum in the tropical regions of the world since about 1950. But its history is long, and stretches far back into the corridors of time when humans first occupied the earth and began to use fire deliberately, probably some half-a-million years ago. All that has changed since the mid-twentieth century is that an ancient process has accelerated, and that, compared to previous ages, environments more sensitive and irreversibly damaged have been affected. Possibly as much as nine-tenths of all deforestation occurred before 1950.
Chopping down trees is part of an age-old human quest for shelter, food and warmth. Trees provide wood for construction, shelter and making a multitude of implements. Wood provides the fuel to keep warm, to cook food and make it palatable, and even to smelt metals. The nuts and fruits of the trees are useful for human foods, medicines, and dyes, and the roots, nuts, young shoots and branches (and the flush of young grass after burning) provide food for animals. Cleared forest provides (at least initially) naturally friable and nutrient-rich soils for growing crops. Clearing requires no sophisticated technology. Humans with stone or flint axes need boundless energy to fell trees; in contrast, fire and browsing animals can wreak havoc with little effort. The substitution of metal for stone axes c. 3,500 years ago, and then for saws in the medieval period, eased the backbreaking task of clearing, and accelerated the rate of change, but it did not alter the basic process of destruction and land-use transformation. Power-saws during the last fifty years have made a major impact.
There is much uncertainty about the pace and locale of deforestation during past (and even present) ages. This revolves around the multiple meanings given to three basic questions. What exactly is a forest? What was the extent and density of trees at any past given time? And what constitutes `deforestation'? Pragmatically one may say that a forest can range from a closed-canopy tree cover to a more open woodland, which affects density. `Deforestation' is used loosely to mean any process which modifies the original tree cover, from clear-felling, to thinning, to occasional fire. However, it should not be forgotten that forests re-grow, often with surprising speed and vigour, and forest re-growth has occurred whenever pressures on it have been relaxed. This was observed, for example, after the Mayan population collapse c.800 AD, after the Great Plague, after the initial European encounter with the Americas, and with agricultural land abandonment in eastern USA post-1910 and post-1980 Europe.
Pre-literate societies everywhere had a far more severe impact on the forests than is commonly supposed. The increase and spread of people, and domestication, took place in largely forested environments. In Europe Mesolithic cultures (c. 9000-5000 BC) did not avoid forests but actively engaged with them, clearing their edges for cultivation, and using fire for game hunting. On the upland fringes of the Pennines, North York Moors and Dartmoor, successive clearings are accompanied by pollens of plants such as sorrel and ribwort plantain, which can only flourish as a result of less tree cover.
The subsequent 2,500 years of Neolithic agriculture (c. 4500-2000 BC) was far more sedentary and stable than once thought: the conventional archaeological wisdom of the Neolithics practising a `swidden' agriculture (rotational burning and clearing for cropping) as they spread across Europe from east to west is no longer subscribed to.
The significance of the widespread incidence of the large, timbered long houses excavated during recent decades has not always been appreciated; many were occupied for centuries, which suggests permanence of settlement. …