A system of agriculture found in areas of tropical rainforest; also known as swidden cultivation. It is a response to loss of soil fertility and vegetation regeneration which occurs after a few years' cultivation, forcing farmers to move to new areas. Slash and burn describes the method of vegetation clearance. In some regions people move on to completely new areas. Elsewhere they live in a permanent settlement and practise a form of land rotation known as bush and fallow, in which vegetation is allowed to regenerate in areas where soil fertility is exhausted. It is then recultivated.
Shifting cultivation is an agricultural system in which a person uses a piece of land, only to abandon or alter the initial use a short time later. This system often involves clearing of a piece of land followed by several years of wood harvesting or farming until the soil loses fertility. An estimated population exceeding 250 million people derive subsistence from the practice of shifting cultivation, and ecological consequences are often deleterious, but are not as severe provided new forests are not invaded. Incorrectly identified as slash and burn (a historic term applied to specific forms of shifting cultivation or to one element of shifting cultivation). Crop rotation (not a proper synonym, but in a best case a possible concomitant element of shifting cultivation). Crop fallowing (the practice of letting a field lie fallow or unused as part of a crop rotation cycle – typically used in dryland farming)
The political ecology of shifting cultivation
Shifting cultivation is a form of agriculture in which the cultivated or cropped area is shifted regularly to allow soil properties to recover under conditions of natural successional stages of re-growth. In a shifting cultivation system, at any particular point in time a minority of 'fields' are in cultivation and a majority are in various stages of natural re-growth. Fields in established and stable shifting cultivation systems are cultivated and fallowed cyclically. During the fallow period, shifting cultivators use the successional vegetation species widely for timber for fencing and construction, firewood, thatching, ropes, clothing, tools, carrying devices and medicines.
The relationship between the time the land is cultivated and the time it is fallowed are critical to the stability of shifting cultivation systems. These parameters determine whether or not the shifting cultivation system as a whole suffers a net loss of nutrients over time.
The longer a field is cropped, the greater the loss of soil organic matter, the reduction in the cation-exchange-capacity and in nitrogen and phosphorus, the greater the increase in acidity, the more likely soil porosity and infiltration capacity is reduced and the greater the loss of seeds of naturally occurring plant species from soil seed banks. In a stable shifting cultivation system, the fallow is long enough for the natural vegetation to recover to the state that it was in before it was cleared, and for the soil to recover to the condition it was in before cropping began. During fallow periods soil temperatures are lower, wind and water erosion is much reduced, nutrient cycling becomes closed again, nutrients are extracted from the subsoil, soil fauna increases, acidity is reduced, soil structure, texture and moisture characteristics improve and seed banks are replenished.
No universal optimum relationship exists between the length of the cropping period and the length of the fallow period. In favourable agricultural environments, cropping periods can be longer and fallow periods shorter, than in less favourable agricultural environments. Nevertheless, even in the most favourable environments, it is likely that if the cropping period is extended beyond a certain point, the fallow conditions required for an adequate recovery of soils and vegetation will be jeopardized.
If the fallow period is shortened there will be less time in which the soil recovery processes and vegetation successions can take place. But sooner or later, if the fallow period continues to be reduced, an observable change will occur in the fallow vegetation. Changes in environmental conditions that happen subsequent to either a lengthening of the cropping period or a shortening of the fallow period often result in a fall in crop yields. It is not difficult to perceive how a shifting cultivation system, once destabilized, can proceed into a vicious circle of declining yields and shortening fallows or lengthening cropping periods, which in turn lead to further degradation of environmental conditions.
The secondary forests created by shifting cultivation are commonly richer in plant and animal resources useful to humans than primary forests, even though they are much less bio-diverse. Shifting cultivators view the forest as an agricultural landscape of fields at various stages in a regular cycle. Rather they perceive an apparently chaotic landscape in which trees are cut and burned randomly and so they characterise shifting cultivation as ephemeral or ‘pre-agricultural’, as ‘primitive’ and as a stage to be progressed beyond. Shifting agriculture is none of these things. Stable shifting cultivation systems are highly variable, closely adapted to micro-environments and are carefully managed by farmers during both the cropping and fallow stages. Shifting cultivators may possess a highly developed knowledge and understanding of their local environments and of the crops and native plant species they exploit. Complex and highly adaptive land tenure systems sometimes exist under shifting cultivation. Introduced crops for food and as cash have been skillfully integrated into some shifting cultivation systems.
Stereotypes: primitive, backward, wasteful, unproductive
Shifting cultivation systems are perceived both by numerous scientists as well as the general public, as primitive, backward, wasteful, unproductive, exploitative and the cause of widespread environmental degradation. Shifting cultivators are blamed for the destruction of much of the world’s tropical forests, land degradation, atmospheric pollution and global climatic change.
While contemporary manifestations of these attitudes towards shifting cultivators are often political and reflect competition between land occupying farmers, migrant settlers, loggers and international capital seeking access to tropical forests, they can sometimes be traced to the late 19th and early 20th century, to European colonial administrations in tropical and sub-tropical South Asia, Southeast Asia and South America. Indigenous occupants were then characterized by the colonizers as primitive and hence their agriculture systems, which were commonly a form of shifting cultivation were also viewed as primitive. In addition, there was a fundamental misunderstanding that shifting cultivators selected sites for cropping at random, thus destroying forests.
These attitudes may have prevented observers of tropical environments from understanding the social and economic conditions underlying shifting cultivation. This chapter implies all shifting cultivation systems are destructive of resources. In the same book another chapter describes massive loss of the forests in Europe prior to the beginning of the 20th century and details the social and economic conditions, other than shifting cultivation, that brought about their destruction (Darby 1956).
Shifting cultivation in Europe
Shifting cultivation was still being practiced as a viable and stable form of agriculture in many parts of Europe and west into Siberia at the end of the 19th century and in some places well into the 20th century. In the Ruhr in the late 1860s a forest-field rotation system known as Reutbergwirtschaft was using a 16 year cycle of clearing, cropping and fallowing with trees to produce bark for tanneries, wood for charcoal and rye for flour (Darby 1956, 200). Shifting cultivation was disappearing in this part of Finland because of a loss of agricultural labour to the industries of the towns. Steensberg (1993, 110-152) provides eye-witness descriptions of shifting cultivation being practiced in Sweden in the 1900s, and in Estonia, Poland, the Caucasus, Serbia, Bosnia, Hungary, Switzerland, Austria and Germany in the 1930s to the 1950s.
That these agricultural practices survived from the Neolithic into the middle of the 20th century amidst the sweeping changes that occurred in Europe over that period, suggests they were adaptive and in themselves, were not massively destructive of the environments in which they were practiced. The question is raised however, if it was not shifting cultivation that led to the disappearance of European forests, what was it?
The earliest written accounts of forest destruction in Southern Europe begin around 1000 BC in the histories of Homer, Thucydides and Plato and in Strabo’s Geography. Although goat herding is singled out as an important cause of environmental degradation, a more important cause of forest destruction was the practice in some places of granting ownership rights to those who clear felled forests and brought the land into permanent cultivation. Evidence that circumstances other than agriculture were the major causes for forest destruction was the recovery of tree cover in many parts of the Roman empire from 400 BC to around 500 AD following the collapse of Roman economy and industry. The other major cause of forest destruction in the Mediterranean environment with its hot dry summers were wild fires that became more common following human interference in the forests. Here, just as in Southern Europe, the demands of more intensive agriculture and the invention of the plough, trading, mining and smelting, tanning, building and construction in the growing towns and constant warfare, including the demands of naval shipbuilding, were more important forces behind the destruction of the forests than was shifting cultivation.
By the Middle Ages in Europe, large areas of forest were being cleared and converted into arable land in association with the development of feudal tenurial practices. With the loss of the forest, so shifting cultivation became restricted to the peripheral places of Europe, where permanent agriculture was uneconomic, transport costs constrained logging or terrain prevented the use of draught animals or tractors. It has disappeared from even these refuges since 1945, as agriculture has become increasingly capital intensive, rural areas have become depopulated and the remanent European forests themselves have been revalued economically and socially.
Simple societies, shifting cultivation and environmental change
The forests of Europe were destroyed by the seemingly inexorable ‘advances’ of civilisation, industrialisation and warfare, the sort of ‘advances’ that many of those who criticised shifting cultivators in the 19th century thought were desirable and indicative of “higher cultures”.
A growing body of archaeological and palynological evidence finds that simple human societies brought about extensive changes to their environments before the establishment of any sort of state, feudal or capitalist, and before the development of large scale mining, smelting or shipbuilding industries. In these societies agriculture was the driving force in the economy and shifting cultivation was the most common type of agriculture practiced. By examining the relationships between social and economic change and agricultural change in these societies, insights can be gained on contemporary social and economic change and global environment change, and the place of shifting cultivation in those relationships.
As early as 1930 questions about relationships between the rise and fall of the Mayan civilization of the Yucatan Peninsula and shifting cultivation were raised and continue to be debated today. More recent work suggests the Maya may have, in suitable places, developed irrigation systems and more intensive agricultural practices (Humphries 1993).
Similar paths appear to have been followed by Polynesian settlers in New Zealand and the Pacific Islands, who within 500 years of their arrival around 1100 AD turned substantial areas from forest into scrub and fern and in the process caused the elimination of numerous species of birds and animals (Kirch and Hunt 1997). In the restricted environments of the Pacific islands, including Fiji and Hawaii, early extensive erosion and change of vegetation is presumed to have been caused by shifting cultivation on slopes. The change from shifting cultivation to intensive irrigated fields, occurred in association with a rapid growth in population and the development of elaborate and high stratified chiefdoms (Kirch 1984). There the stimulus for population growth was the hunting of large birds to extinction, during which time forests in drier areas were destroyed by burning, followed the development of intensive agriculture in favorable environments, based mainly on sweet potato (Ipomoea batatas) and a reliance on the gathering of two main wild plant species in less favorable environments. The root question posed by these and the numerous other examples that could be cited of simple societies that have intensified their agricultural systems in association with increases in population and social complexity is not whether or how shifting cultivation was responsible for the extensive changes to landscapes and environments. Rather it is why simple societies of shifting cultivators in the tropical forest of Yucatan, or the highlands of New Guinea, begin to grow in numbers and to develop stratified and sometimes complex social hierarchies? At first sight, the greatest stimulus to the intensification of a shifting cultivation system is a growth in population. If no other changes occur within the system, for each extra person to be fed from the system, a small extra amount of land must be cultivated. If the area occupied by the system is not expanded into previously unused land, then either the cropping period must be extended or the fallow period shortened. First, population growth in most pre-industrial shifting cultivator societies has been shown to be very low over the long term.
In a study of the Duna in the Southern Highlands, a group in the process of moving from shifting cultivation into permanent field agriculture post sweet potato, Modjeska (1982) argued for the development of two “self amplifying feed back loops” of ecological and social causation. As more forest was cleared there was a decline in wild food resources and protein produced from hunting, which was substituted for by an increase in domestic pig raising.
The outcome of the operation of the two loops, one bringing about ecological change and the other social and economic change, is an expanding and intensifying agricultural system, the conversion of forest to grassland, a population growing at an increasing rate and expanding geographically and a society that is increasing in complexity and stratification. As a result, two fundamental processes underlie the ecology of human social systems: First, the obtaining of materials from the environment and their alteration and circulation through social relations, and second, the giving of the material a value which will affect how important it is to obtain it, circulate it or alter it.
Transitions in ecological systems and in social systems do not proceed at the same rate. If most social systems have the tendency to increase in complexity they will, sooner or later, come into conflict with, or into “contradiction” (Friedman 1979, 1982) with their environments.
An economic study of what occurs at the points of conflict with specific reference to shifting cultivation is that of Ester Boserup (1965). Boserup argues that low intensity farming, extensive shifting cultivation for example, has lower labor costs than more intensive farming systems. Examples of such changes are the adoption of new higher yielding crop, the exchanging of a digging stick for a hoe, or a hoe for a plough, or the development of irrigation systems. The controversy over Boserup’s proposal is in part over whether intensive systems are more costly in labor terms, and whether humans will bring about change in their agricultural systems before environmental degradation forces them to. Parts of the agricultural system may become more specialized, species diversity may be reduced or lost, wild plant and animal resources reduced or lost and ecosystems become more fragile.
Shifting cultivation in the contemporary world and global environmental change
The estimated rate of deforestation in Southeast Asia in 1990 was 34,000 km² per year (FAO 1990, quoted in Potter 1993). Efforts are being made in Indonesia to encourage shifting cultivators to alter the mix of activities and examine alternative cropping patterns, so that the slash and burn portion of their shifting cultivation is a smaller fraction of the time interval of the farming cycle. The outcomes not only reflect less time spent in the slash and burn phase, but also allows a cover crop (rubber) that provides a forest habitatquality much higher than the coffee farm environment.
Shifting cultivation was assessed by the FAO to be one a causes of deforestation while logging was not. The apparent discrimination against shifting cultivators caused a confrontation between FAO and environmental groups, who saw the FAO supporting commercial logging interests against the rights of indigenous people (Potter 1993, 108). One of the outcomes of cash incomes has been rapid population growth among indigenous groups of former shifting cultivators that has placed pressure on their traditional long fallow farming systems. Increased cash incomes often are spent on chain saws, which have enabled larger areas to be cleared for cultivation. The settlers practice what appears to be shifting cultivation but which is in fact a one-cycle slash and burn followed by continuous cropping, with no intention to long fallow. Clearing of trees and the permanent cultivation of fragile soils in a tropical environment with little attempt to replace lost nutrients may cause rapid degradation of the fragile soils.
The loss of forest in Indonesia, Thailand and the Philippines during the 1990s was preceded by major ecosystem disruptions in Vietnam, Laos and Cambodia in the 1970s and 1980s caused by warfare. Forests were sprayed with defoliants, thousands of rural forest dwelling people uproots from their homes and moved and roads driven into previously isolated areas. The loss of the tropical forests of Southeast Asia is the particular outcome of the general possible outcomes described by Ellen (see above) when small local ecological and social systems become part of larger system. Similar descriptions of the loss of forest and destruction of fragile ecosystems could be provided from the Amazon Basin, by large scale state sponsored colonization forest land (Becker 1995, 61) or from the Central Africa where what endemic armed conflict is destabilizing rural settlement and farming communities on a massive scale.
Comparison with other ecological phenomena
In the tropical developing world, shifting cultivation in its many diverse forms, remains a pervasive practice. Shifting cultivation was one of the very first forms of agriculture practiced by humans and its survival into the modern world suggests that it is a flexible and highly adaptive means of production. Many casual observers cannot see past the clearing and burning of standing forest and do not perceive often ecologically stable cycles of cropping and fallowing. Nevertheless, shifting cultivation systems are particularly susceptible to rapid increases in population and to economic and social change in the larger world around them. The blame for the destruction of forest resources is often laid on shifting cultivators. But the forces bringing about the rapid loss of tropical forests at the end of the 20th century are the same forces that led to the destruction of the forests of Europe, urbanization, industrialization and the application the latest technology to extract ever more resources from the environment in pursuit of political power by competing groups.
Studies of small, isolated and pre-capitalist groups and their relationships with their environments suggests that the roots of the contemporary problem lie deep in human behavioral patterns, for even in these simple societies, competition and conflict can be identified as the main force driving them into contradiction with their environments.
User Comments Add a comment…