Slash-and-burn is an agricultural technique that involves the cutting and burning of plants in forests or woodlands to create fields. It is subsistence agriculture that typically uses little technology. It is typically key in shifting cultivation agriculture, and in transhumance livestock herding.
Old terms for slash-and-burn in English include assarting, swidden, and fire-fallow cultivation. Today the term slash-and-burn is mainly associated with tropical rain forests. Slash-and-burn is used by 200 million to 500 million people worldwide. In 2004 it was estimated that, in Brazil alone, 500,000 small farmers cleared an average of one hectare of forest per year each. The technique is not sustainable in large populations, because without the trees, the soil quality becomes too poor to support crops. The farmers would have to move on to virgin forest and repeat the process. Methods such as Inga alley farming have been proposed as alternatives to this ecological destruction.
- History 1
Historical references 2
- Cultures 2.1
Modern Western World 2.2
- Preserving the Northern European Heritage 2.2.1
- South Asia 2.3
- Ecological implications 3
- See also 4
- References 5
- Further reading 6
During the Neolithic Revolution, which included agricultural advancements, groups of hunter-gatherers domesticated various plants and animals, permitting them to settle down and practice agriculture, which provides more nutrition per hectare than hunting and gathering. This happened in the river valleys of Egypt and Mesopotamia. Due to this decrease in food from hunting, as human populations increased, agriculture became more important. Some groups could easily plant their crops in open fields along river valleys, but others had forests blocking their farming land.
In this context, humans used slash-and-burn agriculture to clear more land to make it suitable for plants and animals. Thus, since Neolithic times, slash-and-burn techniques have been widely used for converting forests into crop fields and pasture. Fire was used before the Neolithic as well, and by hunter-gatherers up to present times. Clearings created by fire were made for many reasons, such as to draw game animals and to promote certain kinds of edible plants such as berries.
Slash-and-burn fields are typically used and owned by a family until the soil is exhausted. At this point the ownership rights are abandoned, the family clears a new field, and trees and shrubs are permitted to grow on the former field. After a few decades, another family or clan may then use the land and claim usufructuary rights. In such a system there is typically no market in farmland, so land is not bought or sold in the open market and land rights are traditional. In slash-and-burn agriculture, forests are typically cut months before a dry season. The "slash" is permitted to dry, and then burned in the following dry season. The resulting ash fertilizes the soil and the burned field is then planted at the beginning of the next rainy season with crops such as upland rice, maize, cassava, or other staples. Most of this work is typically done by hand, using such basic tools as machetes, axes, hoes, and makeshift shovels.
Large families or clans wandering in the lush woodlands long continued to be the most common form of life through human history. Axes to fell trees and sickles for harvesting grain were the only tools people might bring with them. All other tools were made from materials they found at the site, such as fire stakes of birch, long rods (vanko), and harrows made of spruce tops. The extended family conquered the lush virgin forest, burned and cultivated their carefully selected swidden plots, sowed one or more crops, and then proceeded on to forests that had been noted in their wanderings. In the temperate zone the forest regenerated in the course of a lifetime. So swidden was repeated several times in the same area over the years. But in the tropics the forest floor gradually depleted. It was not only in the moors, as in Northern Europe, but also in the steppe, savannah, prairie, pampas and barren desert in tropical areas where shifting cultivation is the oldest type of farming (Clark 1952 91-107).
Southern-European Mediterranean climates have always favored open, evergreen, deciduous, and pine forests. After slash and burn agriculture began, this type of forest was less able to regenerate than forests north of the Alps. In Northern Europe, there was usually only one crop harvested before grass growth was allowed to take over, while in Southern Europe it was more common to farm the soil for several years, quickly exhausting it. Slash and burn shifting cultivation thus ceased early in the south, and most of the forests in the Mediterranean region had disappeared by classical times.
Classical authors mentioned the great forests. For example, Homer writes of "wooded Samothrace," Zacynthos, Sicily, and other wooded lands. These authors indicate that the Mediterranean area had more forest once but that much of it had already been lost and was primarily to be found only in the mountains.
Parts of Europe remained wooded, and not only in the North. However, by the Roman Iron Age and early Viking Age, forest areas were drastically reduced also in northern Europe, and settlements regularly moved. There is no known explanation for this pattern of mobility, for the transition to stable settlements from the late Viking period on, or for the transition from shifting cultivation to stationary farming. From this period, plows are first found in both graves and depots. Early agricultural people preferred forest of good quality on hillsides with good drainage, and traces of cattle quarters are evident there.
The Migration Period in Europe after the Roman Empire and immediately before the Viking Age suggests that it was advantageous for the peoples of Central Europe to move to new forests after exhausting old parcels. This exploitation suggests a reason for the rapid and elaborate movement of populations. Forests were quickly exhausted; the practice had ended in the Mediterranean, where forests were less resilient than the sturdier coniferous forest of Central Europe. Deforestation had been partly caused by burning for pasture fields. Reduced timber delivery led to higher prices and more stone construction in the Roman Empire (Stewart 1956 123). Forest also gradually decreased northwards in Europe but has survived in the Nordic countries.
The clans in pre-Roman Italy seem to have lived in temporary locations. They cultivated small patches of land, kept sheep and cattle, traded with foreign merchants, and at times fought each other: Etruscans, Umbrians, Ligurians, Sabines, Latins, Campanians, Apulians, Saliscans, and Sabellians, just to mention a few tribes. These Italic ethnic groups developed identities as settlers and warriors ca. 900 BC. They built forts in the mountains, today a subject of much study, as are the ruins of a large Samnite temple and theater at Pietrabbondante.
The Greek explorer and merchant Pytheas of Marseilles made a voyage to Northern Europe ca. 330 BC. Part of his itinerary was recorded Polybius, Pliny and Strabo. Pytheas had visited Thule, which lay a six-day voyage north of Britain.
There, "The barbarians showed us the place where the sun does not go to sleep. It happened because there the night was very short—in some places two, in others three hours—so that the sun shortly after its fall soon went up again." He says that Thule was a fertile land, "rich in fruits that were ripe only until late in the year, and the people there used to prepare a drink of honey. And they threshed the grain in large houses, because of the cloudy weather and frequent rain. In the spring they drove the cattle up into the mountain pastures and stayed there all summer." This description may fit regions of western Norway.
In Italy, shifting cultivation had become a thing of the past by the birth of Christ. Tacitus describes it as a strange cultivation method practiced among the Germans. He wrote in 98 AD about the Germans that their fields were proportionate to participating cultivators but that crops were shared out by status. Distribution of land was easy because of broad availability. They changed fields every year, with plenty to spare, for they weren't competing to specialize and crowd their crops, only to produce grain. The original text reads, "Agri pro numero cultorum ab universis in vices occupantur, quos mox inter se secundum dignationem partiuntur, facilitatem partiendi camporum spatia praestant. Arva per annos mutant, et superest ager; nec enim cum ubertate et amplitudine soli labore contendunt, ut pomaria conserant et prata separent et hortos rigent; sola terrae seges imperatur." This is the practice of shifting cultivation.
Strabo (63 BC—about 20 AD) also writes about the Suebi in his Geography, VII, 1, 3: Common to all the people in this area is that they can easily change residence because of their sordid way of life; they do not cultivate fields or collect property, but live in temporary huts. They get their nourishment from their livestock for the most part, and like nomads, pack all their goods in wagons and go on to wherever they want. Horace writes in 17 BC (Carmen Saeculare, 3, 24, 9ff.) about the people of Macedonia: the proud Getae also live happily, growing free food and cereal for themselves on land they do not want to cultivate for more than a year, "Vivunt et rigidi Getae, / immetata quibus iugera liberas / fruges et Cererem ferunt, / nec cultura placet longior annua."
Several classical writers, therefore, describe peoples practicing shifting cultivation, which characterized the migration period in Europe. The exploitation of forests demanded constant displacement, and large areas were deforested.
Jordanes was of Gothic descent and ended up as a monk in Italy. In his work De origine actibusque Getarum (The Origin and Deeds of the Getae/Goths), "Gothic Origins and Achievements," the author of 550 AD provides information on the big island Scandza, which the Goths come from. He expects that of the tribes who live here, some are Adogit living far north with 40 days of the midnight sun. After the Adogit come Screrefennae and Suehans who also live in the north. The Screrefennae moved a lot and did not raise crops, but made their living by hunting and collecting bird eggs. Suehans were a seminomadic tribe that had good horses like Thüringians and hunted for fur to sell. It was too far north to grow grain. Procopius, ca. 550 AD, also describes a primitive hunter people he calls Skrithifinoi. These pitiful creatures had neither wine nor corn, for they did not grow any crops. "Both men and women engaged incessantly just in hunting the rich forests and mountains, which gave them an endless supply of game and wild animals." Screrefennae and Skrithifinoi are likely Sami, who often have names like these; "Skridfinner," probably a later form, derived from "skrithibinoi" or some similar spelling. The two old terms, "screrefennae" and "skrithifinoi," probably meant something like "neither Ski nor Finn." Furthermore, in Jordanes' ethnographic description of Scandza are several tribes, and among these are Finnaithae "who were always ready for battle," Mixi, Evagre, and Otingis who lived like wild beasts in mountain caves; "further from them" lived Osthrogoths, Raumariciae, Ragnaricii, Finnie, Vinoviloth, and Suetidi, these last prouder than the others.
The use of fire in Northeast Sweden changed as agriculture changed. Historically the Sami people did not burn land, as it destroyed the lichen required by their reindeer. Later farmers frequently used slash and burn techniqes. During the 19th century the Swedish timber industry moved north, where they would clear the land of trees but leave the waste behind as fire risk. Fires around the 1870s were frequent. There was a fire in Norrland in 1851 and then every ten years, in 1868, 1878, and two towns were lost in 1888.
Modern Western World
Slash-and-burn could be distinctly defined as the large-scale deforestation of acres of forests for agricultural usage. The ashes that come from the trees also help farmers, for they provide nutrients for the soil.
In regions which industrialized, including Europe and North America, the practice was abandoned over the past few centuries as market agriculture was introduced and land came to be owned. For example, slash-and-burn agriculture was initially practiced by European pioneers in North America like Daniel Boone and his family, who cleared land in the Appalachian Mountains in the late 18th and early 19th Centuries. However, the land of such slash-and-burn farmers was eventually taken over by modern systems of land tenure that focus on the long-term improvement of farmland, and discourage the older subsistence practices associated with slash-and-burn agriculture.
Preserving the Northern European Heritage
Telkkämäki Nature Reserve (Kaavi, Finland) is a heritage farm demonstrating the old slash-and-burn heritage. At Telkkämäki farm, the visitor can see how people lived and farmed in the past, when the slash-and-burn agriculture was practiced in the North Savonian region in Eastern Finland from the 15th century. Some areas of Telkkämäki Nature Reserve are burnt annually.
Tribal groups in the northeastern states of India like Arunachal Pradesh, Meghalaya, Mizoram and Nagaland, and also in the districts of Bangladesh like Rangamati, Khagrachari, Bandarban and Sylhet refer to slash and burn agriculture as "Jhum" or "Jhoom cultivation". This system involves clearing a piece of land by setting fire or clear felling and using the area for growing crops of agricultural importance such as upland rice, vegetables or fruits. After a few cycles, the land loses fertility and a new area is chosen. Jhum cultivation is most practiced on the slopes of hills in thickly forested landscapes. The cultivators cut the treetops to allow sunlight to reach the land. They burn all the trees and grasses for clean and fresh soil. It is believed that this helps to fertilize the land, but can leave it vulnerable to erosion. Later they make a hole with a heavy wood or other type chopper in chakma Tāgala. After that seeds of different crops like local/traditional sticky rice, maize, eggplant, cucumber, etc. are planted. Plants on the slopes survive the rainy season floods. Looking at all the effects, the government of Mizoram has launched a policy to end Jhum cultivation in the state.
Slash-and-burn is typically a type of subsistence agriculture, and not focused by the need to sell crops in world markets. Rather, planting decisions are made in the context of needs of the family or clan for the coming year.
Although a solution for overpopulated tropical countries where subsistence agriculture may be the traditional method of sustaining many families, the consequences of slash-and-burn techniques for ecosystems are almost always destructive. This happens particularly as population densities increase, and as a result farming becomes more intensively practiced. This is because as demand for more land increases, the fallow period by necessity declines. The principal vulnerability is the nutrient-poor soil, pervasive in most tropical forests. When biomass is extracted even for one harvest of wood or charcoal, the residual soil value is heavily diminished for further growth of any type of vegetation. Sometimes there are several cycles of slash-and-burn within a few years time span; for example in eastern Madagascar the following scenario occurs commonly. The first wave might be cutting of all trees for wood use. A few years later, saplings are harvested to make charcoal, and within the next year the plot is burned to create a quick flush of nutrients for grass to feed the family zebu cattle. If adjacent plots are treated in a similar fashion, large-scale erosion will usually ensue, since there are no roots or temporary water storage in nearby canopies to arrest the surface runoff. Thus, any small remaining amounts of nutrients are washed away. The area is an example of desertification, and no further growth of any type may arise for generations.
The ecological ramifications of the above scenario are further magnified, because tropical forests are habitats for extremely biologically diverse ecosystems, typically containing large numbers of endemic and endangered species. Therefore, the role of slash-and-burn is significant in the current Holocene extinction.
Slash-and-char is an alternative that alleviates some of the negative ecological implications of traditional slash-and-burn techniques.
- 1997 Indonesian forest fires
- 2006 Southeast Asian haze
- 2013 Southeast Asian haze
- 2015 Southeast Asian haze
- Oil palm plantations
- Slash-and-burn in Heritage Farm, 2012 (Telkkämäki Slash-and-burn Heritage Farm, Kaavi, Finland)
- Slash-and-burn -video (Nordic Museum, Stockholm)
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- Semple E.C.1931, Ancient Mediterranean Forests and the Lumber Trade, vol. II., p. 261-296. Henry Holt et al., The Geography of the Mediterranean Region, New York.
- Homer, e.g., Iliad XIII.11-13, Odyssey IX.22-24.
- Darby, H.C., 1950, Domesday Woodland II Economic History Review, 2d ser.,III, London; Darby, H.C., 1956, The clearing of the Woodland in Europe II, p 186.
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- A W Liljenstrand wrote 1857 in his doctoral dissertation, "About Changing of Soil" (p. 5 ff.), that Tacitus discusses shifting cultivation: "arva per annos mutant".
- Late antique writers commonly used Getae for Goths mixing the peoples in the process.
- G. Costa, 32. Also: De Rebus Geticis: O. Seyffert, 329; De Getarum (Gothorum) Origine et Rebus Gestis: W. Smith, vol 2 page 607
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