The Indonesian islands and their varied landscapes are the creation of tumultuous geological forces and far reaching human intervention. The broad outlines of the archipelago’s geography were shaped over millions of years by the slow movement of continental plates across the Earth, and new details are continually etched into the surface of the region by volcanic eruptions and earthquakes and by the slower processes of erosion and sedimentation. Human beings, however, have further transformed the landscape, removing forest cover, carving rice terraces into volcanic slopes, introducing new species of animals and plants, and harvesting or hunting others, sometimes to the point of extinction. The earliest human impact on the environment can be traced to about nine thousand years ago, but the pace of ecological change has increased dramatically in the last hundred years. Destruction of the environment by deforestation, pollution and overfishing loom as the most serious issues facing Indonesia in the twenty first century. Knowing how the environment has changed in the past, however, is important in understanding the likely impact of recent changes, and this chapter explores the many ways in which the face of the Indonesian archipelago has been transformed in time.
Figure 1.i: Ricefields (sawah), bananas and coconuts. Many features of the Javanese landscape were a product of far-reaching human intervention into the environment.
Most of the world’s dry land is carried on continental plates, huge rafts of rock which have drifted slowly about the surface of the Earth for hundreds of millions of years. 330 million years ago, the continental plates carrying what is now Indonesia were part of an enormous southern continent now called Gondwana, which comprised the present Antarctic, Australian, Indian, African and South American plates, as well as numerous smaller fragments. Gondwana was separated from the northern continent, Laurasia, by the so called Tethys Ocean. Each continent carried its own distinctive flora and fauna: Gondwana was home to marsupials and Araucaria pine trees, while Laurasia was the home of tigers, monkeys and cattle, and of trees such as oaks and dipterocarps.
Approximately 200 million years ago, fragments of Gondwana began to break off and drift north. One of the first of these fragments was a long sliver of continental plate which geologists now call ‘Sibumasu’, because it now coincides with the regions Siam (Thailand), Burma, Malaya and Sumatra. The West Burma plate, together with fragments which later attached themselves to Sumatra, Borneo and Sulawesi, separated from Gondwana about 135 million years ago. By the end of the Cretaceous period, 65 million years ago, India had broken away from Gondwana and a chain of plate fragments stretched between Australia and Asia.
Indonesia’s underlying geological shape continues to change, as the northward movement of the Australian and Indian plates compresses the southern and eastern rims of the archipelago, while the northeast is influenced by movement of the Pacific plate. The movement is slow – a few centimetres a century – but over long periods enough to transform the archipelago profoundly.
The abundance of junctions between continental plates and plate fragments makes Indonesia a region of great geological instability. Earth tremors are common, and major earthquakes have caused great destruction on many occasions. The historical record of earthquakes before the twentieth century is extremely patchy. Only in a few cases can the scale of the destruction or the number of casualties be given with any certainty.
The largest known eruption in the geological history of the region was that of Mount Toba in about 72,000 BCE. This event was a super-eruption, a massive volcanic outburst of a kind which occurs only once in 100,000 years, and it has been estimated that the Toba eruption was the biggest of its kind for two million years, though there were previous massive explosions in about the same place 500,000 and 800,000 years ago. The island of Samosir today lies at the centre of the caldera created by this super-eruption which is estimated to have thrown 800 km3 of ash into the atmosphere. Lava flows covered 100,000 km2 and reached both the Indian Ocean and the Melaka Strait. The eruption possibly lasted only fourteen days, but its consequences were far-reaching. It has been calculated that the volume of ash in the atmosphere, preventing sunlight from reaching the earth, lowered temperatures all around the world by about 10° for several months and depressed global temperatures for several decades. The atmospheric ash dramatically disrupted rainfall patterns, causing droughts in some regions and floods in others. As the volcanic ash settled, it created a layer over the surface of the earth which killed plant and animal life for hundreds of kilometres around the vent site.
Volcanic activity around Lake Toba is currently subdued, but the forces that produced the super-eruption of 72,000 BCE are still at work. Lake Toba lies at the centre of an elevated area known to geologists as the ‘Batak tumour’, produced by a large mass of magma. Within this area there are smaller domes, including Samosir Island itself where the magma has pushed closer to the surface. Two reservoirs are located within ten kilometres of the surface and extend about fifty kilometres into the earth.
Although the underlying geological structure of the Indonesian archipelago was produced over many millions of years, the present outline of the islands of the archipelago is of relatively recent origin. Global sea levels have changed many times during the last million years as water has been locked up in icecaps during ice ages or released during periods of warmer climatic conditions. During the last ice age, which was at its peak about 17,000 years ago, sea levels were about 200 metres lower than today. The islands of western Indonesia then formed a sub continental peninsula, sometimes called Sundaland, stretching southeast from the Asian mainland. In the same period, New Guinea and its adjacent islands formed a northern extension of Australia, sometimes called Sahulland. Archaeological and palaeological evidence suggests that the region was considerably drier than it is now, and that the lowland plains were probably covered with savannah and sparse scrub.
A second cause of change in the physical outline of the Indonesian islands has been sedimentation. The young volcanic rocks of Java and Sumatra erode easily, and during the last two thousand years the northern coastlines of both islands have grown. Determining how much they have grown, however, is difficult. Early maps and descriptions are seldom precise or reliable enough to give definitive information, and ancient historians have had no more than fragmentary materials to work with. Some historians have speculated that most of the areas which are now lowland swamp in Sumatra were sea in fairly recent historical times, but recent archaeological investigation suggests that the coastline two thousand years ago was not greatly different from today.
More reliable evidence of coastal change comes from Java, where coastlines have advanced significantly since the arrival of the Dutch and the start of record keeping on such matters. The deltas of the Citarum and Brantas rivers in West and East Java have grown considerably, while the former coastal city of Demak in Central Java is now nearly twenty kilometres inland.
Volcanic activity and earthquakes are the most striking consequence of the archipelago’s geological instability. Indonesia’s volcanoes stretch in an arc along the length of Sumatra and Java before fanning into a broad zone of instability in Maluku which continues on up into the Philippines.
The historical record of eruptions throughout the archipelago is fragmentary. Relatively complete records were kept only in the 19th and 20th centuries; for earlier eras, only the most destructive events were recorded. The best record of volcanic eruptions comes from Java, where court chronicles, combined with the correspondence and reports of Dutch colonial officials, allow a reasonably complete picture of volcanic activity since the late 17th century. In addition to Java's 21 active volcanoes, there are ten major solfataras, or sulphur fields, many of them in the craters of volcanoes which are not presently considered active.
Java’s volcanic history shows how unpredictable volcanoes are in the long term: some have erupted persistently through recorded history, while others have made their presence felt only in brief, destructive paroxysms. The density of human settlement on Java, however, means that any major eruption in the future will be costly of property and, probably, life.
The most destructive volcanic eruption in Indonesia in recent times was that of Tambora on the island of Sumbawa in April 1815, when two small kingdoms were destroyed and perhaps 50,000 people were killed. Because few Europeans were in the immediate vicinity, not many records of the uprising have survived. In contrast, the 1883 eruption of Krakatau (sometimes called Krakatoa), although less explosive and less destructive than Tambora, has been much better documented.
In early 1883, Krakatau was an uninhabited jungle clad island in the Sunda Strait. It had erupted in 1680, and its three main islands were perched on the rim of a caldera, or volcanic basin, which had been created by a massive eruption at some time in the more distant past. In 1883, however, most observers believed that the volcano was extinct or dormant. In May 1883, an eruption began, with earthquakes, explosions and discharge of ash and pumice, but there was still no inkling of the catastrophe which was to follow.
On 26 August 1883, Krakatau exploded in a series of paroxysms which continued until the morning of the 28th. The pressure generated by super heated steam trapped behind layers of cooled lava was probably responsible for the enormous force of the explosions, which blew away more than half of the main island of Krakatau, leaving a submarine cavity over 300 m deep. The surrounding regions were strewn with ash and pumice, creating new islands (which soon disappeared) and blanketing the land with a thick layer of volcanic materials. The explosions were described as ‘deafening’ in Batavia, and an area 250 km in radius was plunged into darkness by the clouds of ash.
Tsunamis (‘tidal waves’) swept against the coasts near Krakatau, reaching a height of fifteen metres as they beached, killing at least 36,000 people and destroying 165 villages. The noise of the eruption was heard as far as Rodriguez, 4,800 km away in the Indian Ocean, and the tsunamis could be observed without instruments in Madagascar. In several parts of the Indonesian archipelago, the explosions were mistaken for military attacks. Ash entering the upper atmosphere gave rise to brilliant sunrises and sunsets throughout the world.
Krakatau became quiet again in September 1883, but in 1927 volcanic activity was again reported and in 1928 Anak Krakatau (Child of Krakatau) first broke the surface. By 1933, Anak Krakatau was a permanent feature of the region’s geography.
On 26 December 2004 at about 8.00 a.m., a massive undersea earthquake took place off the coast of northern Sumatra. Measuring 9.15 on the Richter scale, the earthquake was the third largest to be recorded on a seismograph. The quake began near the island of Simeulue when part of the India plate suddenly slipped against the Burma plate, pushing deeper and sliding about 15 metres against the Burma plate. Like a rip in a piece of cloth, the rupture then raced northwards at about 10,000 km/hour along the line between the two plates. About ten minutes after it had begun, the rupture petered out where the junction between the India and Burma plates curves to the east.
The quake was felt in Bangladesh, Malaysia and the Maldives but did itself little damage. Parts of the Burma plate, however, were lifted 4–5 metres, displacing an estimated 30 cubic kilometres of seawater and leading to tsunamis which devastated the western coast of Aceh and parts of Thailand, Sri Lanka and India. Damage on a smaller scale occurred on the east coast of Africa from Somalia to South Africa and the waves were observed in Chile and Mexico on the far side of the Pacific. A further earthquake measuring 8.7 on the Richter scale took place off the Aceh coast on 28 March 2005 and a lesser quake of 6.7 affected the west Sumatra coast further south on 10 April. The December earthquake reactivated the dormant Mount Leuser in Aceh, sparked activity in the Toba caldera and may have led to an eruption of Mount Talang in later weeks.
The waves caused by the earthquake spread mainly to the east and west of the fault line, leaving low-lying Bangladesh relatively unaffected while distant Somalia suffered significant damage. It took only about fifteen minutes for the first wave to reach the west coast of Aceh. The waves then continued to come at about 30–40 minute intervals throughout the day, with the third wave the highest and most powerful. In some places the waves reach two kilometres inland. The worst affected area was the west coast of Aceh from the capital Banda Aceh south to Meulaboh. Small villages and towns, close to sea level and often butting against hills, were utterly destroyed. The succession of waves and the accumulating burden of debris meant that those injured or trapped after the first wave were often killed by subsequent ones. There was an especially high death rate amongst children, who were least able to resist the surging waters. It was also reported that more women than men were killed.
In all, it has been estimated that about 289,000 people were killed by the tsunamis, 236,000 of them in Indonesia. More than half a million in Aceh were displaced and spent subsequent months in makeshift camps. The tsunamis destroyed not only houses but roads and bridges, port facilities and fishing boats, contaminated wells and rice fields with salt water.
On 27 May 2006, a further earthquake struck south central Java, causing about more than 6,000 deaths and extensive damage in and around the city of Yogyakarta. The major cause of death was the collapse of unreinforced brick buildings which could not stand the sideways shake produced by the earthquake, which was judged to be 6.3 on the Richter scale, with an epicentre just off the south coast of Java, on the edge of the Java Trench.
The scale of the two disasters revived the perennial question of the historical and social impact of natural disasters beyond the immediate and obvious aspects of human tragedy and economic loss. In its traditional form, this question asks whether repeated natural disasters create a drain on the economy which works against long-term economic development and which perhaps helps to explain problems in economic development in the Indonesian archipelago in the past. Keys has used fragmentary historical evidence to argue that a huge volcanic eruption took place in the Indonesian archipelago in about 535 CE, perhaps on the site of the 1883 eruption of Krakatau. He cites a Javanese text possibly of the period which suggests that the eruption separated Java from Sumatra. The approximate date of this alleged eruption coincides with a significant hiatus in the fragmentary history of state formation in the western archipelago, raising the possibility that an eruption seriously set back the development of civilization in Southeast Asia.
The traditional question also speculates on the psychological consequences of living in the shadow of past and of certain future natural disasters. Some observers claim to find greater fatalism and greater belief in arbitrary divine intervention in societies which are threatened in this way. Others have been more optimistic. The 2004 tsunami was a catalyst for fresh negotiations between the Indonesian government and the separatist Free Aceh Movement (Gerakan Aceh Merdeka, GAM) which led to a cessation of hostilities and an agreement providing for substantial special autonomy for the province. On occasion, it seems, natural disasters can act as a political circuitbreaker.
Serious contemporary research on the social consequences of natural disaster, however, focuses on the social structures generated by both occasional and recurrent natural disasters. There is evidence from the cyclone-prone Philippines that recurrent natural disaster strengthens ideologies of community solidarity, because only communities which respond together to the challenges of disaster survive to deal with disasters the next time. At the same time, natural disasters may tend to favour political fluidity because they erode the practical rule of law.
An unexpected geological phenomenon emerged on 29 May 2006, when heated mud began to spurt from a rupture in the earth’s surface near the town of Porong in East Java. Although the eruption may have been connected with the Yogyakarta earthquake two days earlier, most observers blamed the eruption on oil and gas drilling by the firm Lapindo Brantas. It appears that a drill from the company breached a layer of limestone at a depth of about 2,750 metres, releasing hot water that had previously been held within the earth under high pressure. Forcing its way upwards, the water mixed with clay between 1,300 and 500 metres to produce a torrent of hot, smelly mud rising tens of metres into the air. The mud did not appear to be significantly toxic, but was about as salty as sea water. Although the firm’s engineers predicted that the eruption would soon subside, the volume of mud being expelled instead increased from 5,000 cubic metres per day in June to 125,000 cubic metres in September. It formed a pool which overwhelmed Lapindo’s own buildings and then neighbouring houses. The authorities constructed a series of dams in an attempt to retain the mud, but each of these was overwhelmed by the flood. By October 2006, some 20 factories, 15 mosques, a cemetery and 18 schools as well as a major toll road south of Surabaya were said to lie beneath the 5 km2 muddy lake up to 12 metres deep. 10,000 people had been driven from their homes.
Scientists were able neither to predict how long the eruption would continue nor to suggest how it might be dealt with. The option of diverting the mud by pipeline to the Java Sea threatened fish and prawn stocks there and there was no proven technology to plug the vent. Although the Indonesian government issued regulations declaring Lapindo responsible for compensating victims, the company’s resources were unlikely to be able to meet more than a fraction of the total economic cost.
Indonesia’s turbulent geological history left the region with abundant mineral wealth, whose extraction has been an important source of foreign exchange and which now provides raw materials for Indonesia’s own industrial development. Scattered across the archipelago are subterranean basins containing vast deposits of oil and gas; coal resources are also extensive. Of the world’s major mined minerals, iron ore is relatively scarce and bauxite is present only in limited quantities, but tin, gold, copper and nickel are present in large quantities.
The soils of the Indonesian islands vary enormously in fertility. In a few parts of the archipelago – central and eastern Java, Bali, and parts of northeastern Sumatra – Crecent volcanic activity has left a rich legacy in the form of deep, fertile soils. The volcanic ash in these regions is neutral basic, providing ideal conditions for intensive agriculture. The volcanic soils in western Java, most of Sumatra, Sulawesi and Maluku, on the other hand, are more acidic and are correspondingly less favourable. Still more difficult for agriculture are the older soils of the archipelago, even where they are volcanic in origin. Heavy tropical rain tends to leach nutrients from the ground, leaving a barren laterite subsoil. In Kalimantan and other regions, these soils were once covered with dense tropical rainforest, which gave the impression of great fertility and thus of agricultural potential. The nutrients which sustained that rainforest, however, tended to be recycled from a rather thin layer of decomposing vegetation on the surface. When the rainforest is removed, this source of nutrients also disappears and the soil which remains rapidly declines in fertility.
Even on Java, the contrast between fertile valleys and plains and the infertile limestone hills of the south and centre is striking.
Winds and the rain they bring influenced both the suitability of the Indonesian archipelago for human settlement and the traditional patterns of communication between Indonesia and the outside world. Tropical thunderstorms are an important source of rain in some areas, but most of Indonesia’s rainfall is governed by the two monsoons, which blow alternately during the year. During winter in the southern hemisphere, a stable high pressure system over the Australian desert pushes air northward. The rotation of the earth deflects this airflow so that it reaches Indonesia from the southeast. The mostly dry air of this East Monsoon produces a dry season, which is most pronounced in the Nusatenggara and which is a major obstacle to agricultural development there. During the northern winter, on the other hand, similar high-pressure systems over central Asia and India drive the West Monsoon, which picks up moisture over the Bay of Bengal and the South China Sea and produces a distinct wet season. Within these broad patterns, of course, there is much local variation, especially as a result of local topography. Palu in Sulawesi is reputed to be Indonesia’s driest place, yet it lies only a few kilometres from lush rainforest. A few areas in Java and Sumatra suffer from locally hot, dry winds (foehn).
In some years, the monsoons fail, for reasons which are not fully understood but which are connected especially to changes in ocean currents in the Pacific. These years, which can be identified far back in the historical record, produce catastrophic droughts.
Except on such occasions, the reliability of the monsoons has been a mainstay of traders from the archipelago. The steady alternation of the monsoons led to a trading rhythm, in which vessels caught the East Monsoon on their way from the archipelago to India and China, and picked up the West Monsoon on their return. This change in wind direction meant that it was not possible to travel between India and China in a single season, and the traders’ need to wait for a change of wind at the southern end of the South China Sea contributed to the emergence of major port cities in that region.
Most of Indonesia’s rainfall is produced orographically, that is, when moisture laden winds meet mountainous terrain, rise, and drop their moisture as rain (or as snow on the highest peaks of Irian). Monsoon winds produce most of this rain, but in some places so called zenithal rains are important. These are produced by local winds generated by the sun’s movement during the day. Localized thunder storms can also be a major source of rain. Bogor in West Java experiences heavy rain on average 322 days per year and receives more than twice as much rain as Jakarta, which is only about sixty kilometres to the north.
The fragment of Gondwana which eventually became western Indonesia carried with it a population of plants and animals which had evolved during millions of years when the Tethys Sea separated Laurasia and Gondwana. In the north, evolution had for the most part produced more robust species than in the south, and in the competition for living space after western Indonesia had collided with Laurasia, the southern species were largely eliminated. Only in a few ecological niches, such as the peak of Mount Kinabalu in northern Borneo, do Gondwana species still predominate.
The process began to repeat itself when the Australian plate encountered Southeast Asia 19 million years ago. Adaptable animals such as the pig gradually spread across the narrowing ocean gaps, developing distinct species as they moved. Because, however, the collision was relatively recent in evolutionary terms, the eastern Indonesian archipelago still forms one of the most important bio geographical frontiers in the world. The sharp contrast between Asian flora and fauna in the west and Australian flora and fauna in the east was first noted in the mid 19th century by the British naturalist Alfred Russell Wallace, who identified the frontier as running between Bali and Lombok and between Borneo and Sulawesi. Scientists now see the whole region encompassing Sulawesi, Maluku and Nusatenggara as a transitional one and refer to it as Wallacea.
Figure 1.ii: Orang-utan, as portrayed by A.R. Wallace. The striking similarities between human beings and apes such as the orang-utan were one of the scientific observations which pointed in the direction of an evolutionary origin for humankind.
The most dramatic ecological impact on the Indonesian archipelago in recent times has come from human beings. Since agriculture began in the highlands of New Guinea about 7000 BC, Indonesia’s natural environment has been under pressure. Forest has been cleared for farming and plundered for firewood, building timber and useful forest products. Animals of the forest have been hunted, either for food and trade or because they represented a hazard to humans. The landscape has been reshaped and new species have been introduced on a vast scale. Serious work on Indonesi’'s environmental history has begun only recently and it is too early to present a comprehensive picture of modern ecological transformation in the archipelago. The task is made difficult by the imprecise identification of plant and animal species in many early accounts, and by uncertain evidence of the extent of Indonesia’s vegetation before the 20th century.
The onslaught on Indonesia’s forests has taken place in three overlapping phases. For many millennia, the dominant agricultural mode of people living in the Indonesian region was swidden, or shifting cultivation. An individual or community would clear a patch of forest, generally burning the felled trees and shrubs, and would plant a crop. Taro, yams, sago, millet, bananas and sugarcane were probably prominent amongst these early crops, though the exact mix of plants depended on local circumstances. After two to three years, the fertility of the tropical soil began to diminish and the farmer moved on to a new clearing, leaving the old plot to revert to jungle over a period of perhaps twenty to thirty years.
Swidden agriculture certainly affected the structure of tropical forests, but opinions differ over whether it was any more significant than natural destructive forces such as landslides and lightning strikes. In some areas of the archipelago, especially Java, swidden agriculture was largely replaced by settled agriculture in early historical times, but it persisted, especially in Borneo and New Guinea, well into the 20th century. The fact that it is now seldom practised in Indonesia is due partly to the hostility of governments which – against a considerable body of evidence – see swidden as inefficient, uncivilized and environmentally destructive, and partly to the destruction of swiddeners’ forests by large scale commercial logging.
Trade also contributed to forest destruction. Individual plant species with a high value in international markets – camphor (kapur) in early times, and more recently sandalwood (valued for its fragrance), jelutung (a precursor to rubber) and ebony – have been ruthlessly removed from forests.
A second phase of forest destruction began as a result of settled cultivation, for both subsistence and trade. Very little is known of the earliest settled agriculture of the archipelago, except that rice was probably not a dominant part of the local diet, even on Java, until well into historical times. Rice cultivation probably developed in the more temperate regions in what is now northern Southeast Asia and southern China, and it was many centuries before varieties suited to the moist tropics were developed. There is abundant evidence, however, of settled communities feeding themselves on the produce of permanent fields and finding products – first spices and later other food crops – to trade with other communities. The human population of the archipelago began to grow, and pressure on the forests for firewood and building timber increased. Contact with the Americas from the early 16th century added maize and cassava to the agricultural repertoire and allowed cultivation to expand into new areas. Nonetheless, even in the early 20th century, more than half the area of the archipelago was still densely forested.
The scale of forest destruction in Indonesia has increased enormously since 1967, when the Indonesian government began to encourage large scale logging for export. Although relatively sound regulations were put in place to ensure the sustainability of the logging industry, there was little supervision and infringements were rife, especially in the early decades. Just how much forest has been lost is difficult to say, partly because destruction has been deliberately concealed, partly because regrowth forests and even plantations are sometimes recorded as forest cover alongside old growth natural forest. Consequences of forest clearing include more acute flooding during the wet season, erosion and the loss of forests as a source of harvested products such as rattan. Some logged over areas have re grown, but others have become covered with hardy alang alang grass (Imperata cylindrica). Alang alang forms a dense mat in which forest cannot easily re establish itself and it thrives on regular fires, which destroy tree seedlings.
A multitude of environmental problems now besets Indonesia. Industrial pollution affects air, water and land in many parts of the archipelago; population growth and rising affluence also increase demands on natural resources, from forest products and fish to water and fuel.
Indonesia’s record of dealing with these problems has been mixed. On the one hand, the government has adopted the rhetoric of long term sustainability and has enacted legislation and regulations based on some of the best modern practice. Indonesia’s record in managing environmental problems arising from the Green Revolution has been especially impressive. In the fields of pollution control and forest management, on the other hand, a combination of officially sanctioned disregard for regulations and a lack of administrative capacity has permitted serious environmental degradation.