Reg Environ Change (2006) 6: 86–100 DOI 10.1007/s10113-005-0009-2
O R I GI N A L A R T IC L E
Franck Lavigne Æ Yanni Gunnell
Land cover change and abrupt environmental impacts on Javan volcanoes, Indonesia: a long-term perspective on recent events
Received: 9 May 2005 / Accepted: 7 September 2005 / Published online: 11 February 2006 Springer-Verlag 2006
Abstract Based on a presentation of the spectacularly abrupt environmental and societal processes occurring on Java since the 1990s, and using that as an analogue to compare their consequences with the known environmental history of the island, we unravel the relative contributions of natural and human impacts in shaping the environment of Java. Our work is based on remote sensing, Geographical Information System analysis, field-based observations and measurements of responses to abrupt land cover changes in the last 10 years. Ecological disturbance has been endemic to the long-term history of Java, but montane forests on volcanoes have since ca. 1990 become the last frontier of colonisation and are for the first time rapidly receding. We reveal how human disturbance of natural ecosystems, today as in the past, tends to be the greatest where resistance is the least. This appears true within the regional setting of Southeast Asia, where Javan forests since the last glaciation have constituted a biogeographical ecotone with a limited natural ability to regenerate after some imbalance. It is equally true at the scale of single events where humans will turn a natural disturbance to their own advantage. Overall, it remains difficult to deconvolve the signals of spontaneous human impacts and of localised natural events such as volcanic activity, El Nin˜o-related forest fires or longer climatic anomalies because humans are opportunistic in their attitudes to natural variability and so the two are often inextricably linked. The clearest impact on land cover and land degradation comes from the history of state-organised deforestation, whether colonial or indigenous, because its impact has been systematic, pervasive and regionally consistent. Javan environments have shown astonishing Electronic Supplementary Material Supplementary material is available for this article at http://dx.doi.org/10.1007/s10113-0050009-2 and is accessible for authorized users. F. Lavigne (&) Æ Y. Gunnell Laboratoire de Ge´ographie Physique, CNRS UMR 8591, 1 Place Aristide Briand, 92190, Meudon, France E-mail:
[email protected]
signs of resilience under the abrupt, cumulative impacts that have been inflicted over the last four centuries in successive iterations, possibly because the high-energy tropical and volcanic environment is a system in which sediment turnover is naturally rapid and where past scars of land degradation either heal rapidly or are soon destroyed by younger events. However, the volcanoes are the island’s keystone reservoirs of water, sediment and biodiversity and command the geomorphic metabolism of the lowlands. By removing forests from increasingly crowded mountain slopes, Javanese society is following a trajectory in which new nonlinear responses to environmental hazards and change may limit our capacity to anticipate and contain environmental risk to human life and property. Keywords Volcanoes Æ Land cover Æ Land degradation Æ Ecotone Æ Natural hazards Æ Economic crisis Æ Nonlinearity Æ Java
Introduction Most studies of Indonesian forests have focused on Outer Indonesia, where 97% of forests are found (e.g. Whitmore 1981, 1984). The island of Java, in contrast, represents Inner Indonesia: only 7% of the land area and 3% of the forest, but 67% of the population. Its agroeconomic and environmental identity are entirely different: dominated by rice and sugarcane, Java is probably the most accomplished exemplar in the Tropics of state-organised timber mining and abrupt environmental destruction, where ‘scientific’ forestry spawned in engineering schools of France and Germany was implemented by Dutch colonisers after 1796, refined, and soon exported to other forested regions of the Tropics (Peluso 1992). Although 23% of Java remains classified as state forest (7% protected or reserved, 16% for production), much of it involves plantations, and therefore low richness, low diversity and a single canopy layer. As such, and given that ecological complexity is
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commonly believed to be a major attribute of ecosystem resilience, Java is to many analysts a shocking epitome of the deleterious ecological effects of agricultural and forestry monocultures. These carry all the potentially disastrous consequences suffered by simplified ecosystems in terms of vulnerability to pests through loss of biodiversity, and of flood hazards, slope instability, and soil erosion. The link between land cover change and land degradation is strong in most environments. Investigating land cover change, however, requires discernment, as woods do not cease to exist simply by being felled any more than a meadow ceases to exist after a crop of hay (Rackham 1986). Asking why a wood disappeared does not directly address why it did not grow again. Linking knowledge of the past with processes of the present lies therefore at the borderline between political economy and the environmental sciences, and requires an examination of both historical and geological archives. In this paper we do both, our basic hypothesis being that woodland increases infiltration over runoff, so deforestation modifies runoff coefficients and hence affects sedimentary systems on slopes and in river floodplains in a specific and recognisable way. Based on a presentation of the abrupt environmental and societal processes occurring on Java since ca. 1990 and using that as an analogue to compare those impacts with the known environmental history of the island, we attempt to unravel the relative contributions of natural and human impacts in shaping the environment of upland Java. The island being highly susceptible to natural geomorphic hazards, we track whether the geomorphic scars of land cover change have followed recurrent patterns throughout the Holocene, or whether the environmental stigma recorded in the late twentieth century are unique and unprecedented. We also evaluate whether the cumulative environmental impacts through time have had lasting systemic consequences on the geomorphic systems of Java, or, given the literature on the astonishing resilience of Javanese society (particularly, its wetrice agro-ecosystem: Geertz 1963), whether we are also dealing with a particularly resilient environment.
Methods Although the surface covered by the remaining forests of Java has decreased drastically in most parts of the island since the 1990s, data to substantiate this and reports on collateral geomorphic and hydrological impacts of deforestation are rare. When they exist, their accuracy is doubtful because they come either from unpublished reports of the State Forest Corporation (SFC), which has a vested interest in underestimating clear-felling of forests under its responsibility, or from journalists. Here we present first-hand data on deforestation rates based on satellite image processing and subsequent spatial analysis at the regional scale using a Geographical
Information System (GIS: ArcView). Forest recession was studied through a combination of aerial photographs (1993), panchromatic Spot images (1997) and a set of multispectral Spot and Landsat TM images (1979, 1991 and 2001) of Mts Sumbing and Sindoro. We systematically applied the same image processing protocol to several other volcanoes in Central Java, including Dieng, Merapi, and Merbabu, and Mts Welirang, Arjuno, Kawi, Anjasmoro and Semeru in East Java (Fig. 1). Image processing was completed at each site by 12 months of field surveys, carried out during the rainy season and spread over the period 1999–2003, in order to update the land cover data, complete our database and assess the geomorphic and other environmental impacts of abrupt deforestation on the ground. This involved collecting existing hydrological, climatic and geomorphic data from local offices (PT Jasatirta: Malang; Brantas Project: Surabaya; PT Indonesian Power: Banjarnegara; BRLKT and BCEOM: Yogyakarta; BPTDAS: Solo); and acquiring first-hand data through field measurements of soil erosion, sedimentation in reservoirs and river suspended loads (Cimanuk, Serayu, Progo, Brantas, Konto, etc.). We also studied the context and impacts of several deforestation-related disasters that occurred between 1999 and 2003.
Results Abrupt clearance of forests on Javan volcanoes since the 1990s Observational evidence With ca. 120 million inhabitants and averages of 700– 900 people per square kilometre on agricultural land in hill areas, Java is the most densely populated region of South-East Asia and has maintained some of the most intensively used agricultural land in the world for centuries. As a result, extensive tracts of sparsely inhabited and unlogged forest are almost absent, except for a few natural forest patches protected as nature reserves (731,000 ha in 1990) and monospecific protection forests (419,000 ha in 1990). These are mainly located on the higher slopes of the volcanoes. These forests are managed by the SFC, which is also in charge of 1.8·106 ha of production forests in 1990 (Suwardi Machfud 1990). Until recently, highland forest has survived due to remoteness and impracticalities of agricultural development. However, the montane forests have become the last frontier of colonisation in Java as observed in the context of the 1997 economic crisis. Everywhere on the island, forest clearance on the volcanic slopes has reached its highest rates since the colonial period. A clear example is given by the flanks of the Sumbing and Sindoro volcanoes (Central Java), where the forested areas have been declining since the late 1980s (Fig. 2). The forested area declined at a very low rate from 1979
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Fig. 1 Location of the main volcanoes and rivers (white lines) of Java, and sites mentioned in the text
to 1994 (700 ha cleared). The accelerated recession between 1994 and 1997 (7,100 ha lost in 4 years) is mainly due to fires that occurred in Central Java in 1995. Since 1997, high deforestation rates (600 ha year 1) result from the upslope expansion of tobacco fields by local farmers. The trend is similar on the volcanic slopes of East Java where the forest areas drastically decreased between 1990 and 2000 (Fig. 3). Based on local-scale field enquiries, it is clear that current deforestation has not affected all types of forest equally. Private and communal forests (hutan rakyat) suffer little from logging. The principal victims of spontaneous forest clearance are the state forests (hutan
negara) managed by the SFC. Protected teak forests in the nature reserve on the slopes of Mount Welirang (East Java), for instance, are being rapidly thinned by illegal loggers. Some forests recently managed by the SFC have been converted to agriculture, as observed in the Mondo river catchment north of Kebumen. Even areas that were reforested at the end of the 1980s or at the beginning of the 1990s through a Regreening Programme currently suffer from illegal logging. For example, the surface area of reforested slopes in the Upper Kali Konto Project (East Java) decreased from 29,625 to 24,843 ha between 1994 and 2003, i.e. a loss of 16% in 9 years (Boun Heng et al. 2004). In the mid1990s, administrators of the Dieng Plateau in Central Java received an award for the success of its reforestation and land conservation plan. In 2000, 60% of the 20,000 ha of forest in this region had already disappeared (Guyomarc’h 2003). Causes and mechanisms
Fig. 2 Decrease of the forest area on the Sumbing and Sindoro volcanoes since 1979 (after Texier 2003)
The causes for late twentieth century deforestation on Java are unprecedented. The years 1997 and 1998 were a turning point for Indonesia. With a financial crisis affecting the Far East, Indonesia sank into a deep economic and political crisis. The stock exchange crashed and the devaluation of the rupee caused many bankruptcies. This situation was worsened in Indonesia by three aggravating circumstances. Firstly, the years 1997 and 1998 recorded the strongest ENSO anomaly
89 Fig. 3 Forest recession in the Brantas watershed between 1990 and 2000. This GIS thematic map results from a spatial analysis based on two colour composite Landsat TM satellite images
of the twentieth century. The intense El Nin˜o-generated drought of 1997, followed by catastrophic La Nin˜arelated floods in 1998, destroyed the food resources of the country, which had to import rice to prevent famine. Secondly, the fall in oil prices by 30% compared to the previous year caused a sudden state treasury deficit. Thirdly, austerity measures imposed by the International Monetary Fund plunged the population deeper into insecurity. Prices of consumer goods rose rapidly, triggering social unrest which ended in the fall of the New Order regime of General Suharto. The political vacuum left in the wake of this regime change, or Reformation, left the country in a state of socio-economic chaos. In the rural areas, impoverished farmers encroached on forest lands to grow subsistence crops. These efforts by villagers to illegally occupy the forest are the continuation of a civil disobedience tradition started during the colonial period (Peluso 1992), but in 1997–1998 they were specifically driven by the lack of access to land for farming, lack of employment opportunities and low household incomes. Whereas forest clearance was a localised and discrete phenomenon at the beginning of the 1990s, after 1997–1998 it increased in intensity everywhere in Indonesia, including the volcanic slopes of Java. Different strategies were adopted by the peasants to make arable land available on the upper slopes of volcanoes. The easiest and least confrontational tactic was not to fight the El Nin˜o-related forest fires in 1997. Newly burned slopes were used by the farmers for planting subsistence crops even though the land was still under the jurisdiction of the SFC. We observed a similar attitude during the extensive fires that burned the state forests on the slopes of the Merapi and Merbabu volcanoes in October 2002. A second and more active farmer tactic consisted in invading a state forest in order
to convert it to agriculture. Invaders were either local villagers, as on the southern flank of Mount Sindoro, or exotic groups in conflict with the local farmers, as on the northern flanks of Mount Welirang (Chenet 2003). In both the cases, encroachment on state land remains illegal. The Reformation has been advertised by the media as the main scapegoat for current environmental problems. However, in many upland areas, deforestation is not a new phenomenon. It is rather the acceleration of a process that has lasted for decades. Lands under the jurisdiction of the SFC and classed as protection forests are called ‘‘disputed lands’’ (tanah sengketa: Suwardi Machfud 1990). This problem has been attributed to conflicts over production policies inherited since the Second World War between the SFC, the Department of Agrarian Affairs (Departemen Kehutanan) and individual farmers (Peluso 1992). Illegally cultivated forests and estate lands on Java already covered >105 ha in the 1980s (Palte 1989). This was conspicuous on militaryowned land, where farmers are allowed to cultivate certain tracts. In other areas called magersari lands (lands made temporarily available by the state), tolerated forest camps are converted by landless farmers into permanent settlements. These fait accompli end up being unofficially accepted by the SFC. Since the 1980s, the traditional subsistence crops and coffee plantations in the upper and mid-slopes of volcanoes have progressively been transformed into an agricultural production system dominated by commercial crops (sugarcane and tobacco). During colonisation these were mainly confined to the low-elevation floodplains. Nowadays, apple orchards cover the slopes of Mt Arjuno near Malang, potatoes have become a monoculture in the Dieng caldeira, and tobacco fields reach their thermal limits on the slopes of the Sumbing and
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Sindoro volcanoes. As a result, subsistence crops have also been progressively pushed upslope towards the steeper areas, with poor terracing or shelter planting systems and increased erosion hazards. This is the price to pay for personal enrichment: in 2001, the average annual takings of a potato planter at Dieng reached 26 millions rupiah (i.e., 2,600€: Balai Teknologi Pengelolaan Daerah Aliran Sungai, 2002, unpublished data), which is equivalent to the annual income of a university professor in Indonesia. As in other mountains of the Tropics, this phenomenon is related to the rising demand in cool climate fruit and vegetables from corporate multinationals (potatoes on the Dieng Plateau are commissioned by, among others, Kentucky Fried Chicken) and from the population in the rapidly growing cities. The end of the 1990s is therefore marked by an unprecedented shift to highland farming on volcanic slopes above 1,200 m a.s.l. (Ruthenberg 1980; Palte 1989; Nibbering 1997). By effectively ushering in the conversion of protection forests to agriculture on the disputed lands at high elevations, the Reformation acted as an abrupt and significant increment in a secular trend of land degradation. Environmental impacts of the post-1997 land cover crisis Disturbances of physical resources There are several examples in Java where it is proven that forest clearing disrupts the climate at the local scale. On Dieng Plateau, e.g. frost during the dry season has been reported for the first time whereas this phenomenon was still unknown at the beginning of the 1990s. Around Malang city, deforestation caused by urban growth has recently increased recorded daily maximum temperatures. During the dry season, high deforestation rates increase the chronic water resource problem of the dry season related to the high permeability of volcanic soils. For example, on the south flank of Mt Arjuno, spring discharge at the source of the Brantas, one of the largest rivers in Java, recently decreased from 7 m3 s 1 to less than 1 m3 s 1 (P.T. Perum Jasa Tirta, oral
Fig. 4 Sediment progradation wedge in the Sudirman reservoir on the Serayu river since its construction in 1989. The reservoir has accumulated more than 60·106 m3 of sediments, which represents 40% of the storage capacity (unpublished data from PT Indonesian Power). Sedimentation peaked in 2000 (7·106 m3) at the onset of forest clearing on the rims of Dieng caldeira
communication, 2002). As a result of high sedimentation rates, and due to water pumping for irrigation of the new potato fields that have replaced the forests since 2000, some volcanic lakes in the Dieng caldeira such as Telaga Balai Kambang or Telaga Swivi now dry out during the dry season. This is unprecedented within human memory. Everywhere on the volcanic slopes in Java, erosion rates have increased significantly since the Reformation. Data from several experimental erosion monitoring plots have given rates of 50–60 t ha 1 year 1 in tobacco fields on the slopes of the Sindoro and Sumbing volcanoes. Rates reach 400 t ha 1 year 1 in potato fields on Dieng Plateau (Guyomarc’h 2003). In 2002, calculated soils loss rates ranged from 4.21 mm year 1 in the upper Serayu catchment to 13.7 mm year 1 in the upper Merawu catchment, whereas rates in the 1990s never exceeded 2 mm year 1 in either of those (Balai Rehabilitasi Lahan dan Konservasi Tanah Opak-Oyo-Serayu, oral communication, 2002). Therefore, past affirmations that slope erosion rates in volcanic areas were up to ten times lower than in the sedimentary hill zones of Java, where deforestation has historically been extreme (e.g. Karmono 1980), are no longer valid in the current environmental context where accelerated soil erosion is also affecting the volcanoes. The hiatus between a temporary but abrupt socioeconomic situation such as the Reformation, and the definitive impact this has on erosion systems and environmental balances, epitomises the dramatic situation of the Javan environment today: avoidable or reversible economic instability generates lasting changes in the physical environment. The high erosion rates in the upper volcanic catchments result in rapid siltation of the downstream reservoirs, thus reducing their life span and leading to considerable financial loss. This has been recorded at the Sudirman reservoir on the Serayu River (Fig. 4), and in the reservoirs of the Brantas River: from 1997 to 1999, the Sutami reservoir was filled by 7.1·106 m3 of deposits (Perum Jasatirta, unpublished data). In the upper Konto watershed, the storage capacity of the Selorejo reservoir decreased from 42.8·106 to 36.5·106 m3 between 1999 and 2003 (Boun
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Heng et al. 2004). Resulting from high erosion rates, an increase in suspended load has been observed in several rivers such as the Konto, where daily data sampled at the Selorejo dam are available since 1997 (Fig. 5). In this river, the increase in sediment discharge since the Reformation is related to the increase in rainy season river discharge. Figure 6 shows that this recent trend does not reflect the hydrological evolution of the Konto River during the last half-century. Despite great discharge variations in the Konto River, three main periods may be distinguished: 1957–1982, when rainy season runoff was very high relative to annual rainfall (related to a period of deforestation); 1982–1998, when, due to a period of forest recovery as part of the Upper Kali Konto Project (1979–1988), extreme discharges were subdued even when annual rainfall was high; and post-1998 when again river discharges rose despite a decline in rainfall (renewed deforestation since the Reformation). Increasing hazards and societal risks Population densities have not only risen in cities but also on the volcanic slopes. Recent deforestation in Java has thus increased both natural hazards and risks to human life and property. While some hazards occur chronically throughout the island, others are more specific to either the western or eastern parts of the island. The highenergy Javan environment being naturally prone to frequent catastrophic events, caution should be taken before systematically pinning on deforestation every disaster that occurs each year because correlations are not always supported by fact. Nevertheless, recent forest clearing by Madurese immigrants on the southern flank of Mount Semeru (Fig. 3) has increased volcanic hazards because pyroclastic flows and surges, and over-
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flowing lahars, are no longer slowed down by trees. Flash floods often evolve into debris-flows, called banjir bandang, due to the high sediment supply from the clearfelled or only recently reforested slopes. The most recent disaster related to this hazard occurred on the Cumpleng river in Pacet (Mt Welirang, East Java) on December 11, 2002 (Chenet 2003). Transporting large boulders, the debris flow destroyed a spa complex and killed 26 bathers as a consequence of recent deforestation on the northern slope of Mount Welirang. This is consistent with another large flash flood that occurred four years earlier (La Nin˜a: 1998), while no event of this type had been previously recorded within living memory. Among the 970,000 ha of forests that cover West Java, 50% are considered as critical lands by the SFC. In the wet environment of this region, major hazards and risks are related to landslides: in 2001, 40 out of the 54 landslide events that occurred in Indonesia occurred in West Java. In 2002, landslides killed 71 people in Indonesia, 51 of those in West Java (Dr. Surono, head of the Geological Hazard Mitigation Division, Directorate of Volcanology and Geological Hazard Mitigation, 2003, personal communication). In some specific geomorphic contexts, a landslide that has dammed a deep valley may trigger a mud or debris flow due to sudden dam breaching. Such an event occurred on Mt Kelut (East Java) in 1994 and Mt Guntur in 2003. During the last eruption of the Papandayan volcano in November 2002, the water of three lakes ponded by landslides was suddenly drained off after the lakes were filled by material from a debris avalanche. The resulting lahar progressed downstream in successive pulses for ca. 9 h and destroyed 245 houses (Lavigne et al. 2003). In such cases, the disaster results both from a natural event and from human recklessness as the landslides in that particular chain reaction were caused by forest clearing. In the drier lands of Central and East Java, landslides are less frequent. Forest fires, partly of human origin, are the main cause of land cover change and the initiation of abrupt geomorphic processes. Illegal logging is responsible for large gaps in the forest canopy, allowing the rapid growth of fire-sensitive undergrowth species that increase the vulnerability of the forest. As a result, the October 2002 fires (see Appendix S1) burned 500 ha of forests at the Arjuno-Lalijiwo Natural Reserve, and 300 ha on the slopes of Mt Merapi, where an additional 1.2·106 m3 of water were lost as a consequence of spring quelling (data from the Ministry of Forests). In this environmental context, a few conservation measures have been implemented, such as the incitation of farmers to substitute tobacco for coffee trees on the slopes of Mts Sumbing and Sindoro, in agreement with the SFC. Other soil conservation projects, for instance in the upper Mondo catchment, involve reforestation programmes. These are mostly based on the planting of young pine trees (Agathis), occasionally mixed with nitrogen-fixing lantorogung (Leucaena leucocephala). However, such programmes are sometimes unsuccessful: in the summer of 1999, for instance, the regional Forestry
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Fig. 6 Monthly discharge of the Konto river and annual rainfall at Selorejo dam since 1957 (after Boun Heng et al. 2004). The discharge curve shows a sinusoidal shape which reflects normal fluctuations between the rainy season and the dry season. A detailed analysis shows a tendency towards an abatement of extremes through time, contrary to the rain-related curve which
shows a clear increase of extremes since 1983. This sharp contrast between the hydrological and rainfall data is even more obvious since 1998. The last 5 years were characterised by a regular drop in the annual rain totals whereas flow discharges have tended to rise. The conjunction results from recent land cover changes in the upper watershed since the Reformation
Department of Cilacap district decided, in agreement with the local population, to clear a teak forest in order to replace it with pine trees. These are more lucrative for the local people in the short term. All previous trees were logged and replaced by young 30-cm-high pine saplings and subsistence crops such as peanuts, cassava, sweet potatoes and banana plants on steep slopes. Geomorphic impacts were almost immediate: the first heavy rainfall following the land cover change triggered several shallow landslides (Fig. 7), and this has recurred every year during the rainy season since 2000.
before Dutch colonisation) and annuals in the plains contributed to accentuate the bipolar character of the botanical landscape between the sawah and tegal agroecosystems. Tegal itself is a substitution by permanent crops to the traditional ladang, or short-cycle swidden plot, which today survive among limited ethnic groups in remote hill areas of West Java, where the Dutch demarcated tolerance areas rendered essentially unsustainable due to their small size. Despite these impacts, it remains extraordinary that no dramatic change of a systemic nature has been inflicted on the Javan environment until very recently. We now discuss in greater detail the long-term trajectory of land cover change on Java, and examine both why that island, rather than any other, became Inner Indonesia, and what the main distinctions are between human and natural impacts based on past records.
Disturbance and resilience of Javan ecosystems: how the long view informs the present The history of the Javan environment is one of cumulative impacts in which successive iterations of abrupt deforestation have intensified ecological disorders. The century 1830–1930 inspired what Geertz (1963) has called the ‘agricultural involution’ of Java: without changing its essential structure, the wet-rice (sawah) agro-ecosystem absorbed into its mould new cash-crop substitutions to paddy and adjusted by making its inner workings ever more complex (rotational cropping on rice fields). The engine of colonial prosperity was the apparently limitless labour force, but its resilience was, eventually, pushed to the limits and to the detriment of subsistence paddy cultivation. The solution to relieving the strain on the lowland sawah agro-ecosystem was either to emigrate (organised Transmigration) or to turn to ever more intense tegal dry-cropping (crop-and-fallow dry fields on hillsides) on ever steeper slopes. As elsewhere in the Tropics, firewood cutting has been responsible for ‘illicit’ deforestation as a consequence of coercive restriction of access to forest resources by the state (Gillis 1988). The partitioning between perennials in the mountains (except for spices, grown in the swidden systems long
Fig. 7 Shallow landslide occurrence after deforestation of a teak forest in Cilacap prefecture (Photo: F. Lavigne)
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Palynology is widely used to reconstruct past floristic assemblages and obtain a measure of differences between modern vegetation and past patterns of land cover. However, its potential as a tool for reconstructing lowland tropical floristic assemblages is limited on Java because most native lowland species have disappeared from the present-day vegetation. As no modern analogues of natural vegetation really exist, it remains difficult from a study of the modern pollen rain to calibrate and characterise the ecological boundary conditions of the past through the use of transfer functions. The few existing studies of modern pollen spectra in lowland lakes on Java (Beuning 1996; van der Kaars et al. 2001) show that the pollen signal essentially reflects local vegetation. Lakes with similar moisture regimes may show similar pollen spectra, but signals unique to individual lakes also exist. So, detecting the intensity of human overprints on natural changes in land cover during the past and understanding forward ecological trajectories to the present on the basis of floristic indicators remains problematic due to the difficulty in extracting regionally meaningful signals out of diverse local situations. Despite these difficulties, potential vegetation types on Java have been reconstructed. Historically, natural ecotones have fallen prey to human disturbance much earlier than biome core zones. Java seems to be no exception. Although the colonial and post-colonial impacts, examined later in the discussion, were decisive in transforming the land cover of Java, intrinsic reasons for its more rapid degradation than in Outer Indonesia lie in its biogeographical position within SE Asia. Contrary to the two core areas of perhumid and aseasonal equatorial rain forest in Sundaland (to the north-west) and Papuasia (to the east), Java is characterised by a seasonal monsoon climate with only one area of rainforest restricted to the western uplands. The eastern part contains large enclaves of sharply seasonal climates, which represent the westernmost outposts of drier climates that prevail in the Moluccas and Lesser Sunda islands. In East Java,
rainforests thus only survive as isolated pockets on the south-facing slopes of elevated volcanoes where clouds persist and rain is received from onshore winds. The position of Java at the periphery of the adjacent rain forest biomes is reflected in its sharing 21–37% of its plant flora with all of the neighbouring biogeographical island groups (Whitten et al. 1996), and its natural forests are, relatively, species-poor (Backer and Backhuizen van den Brink 1963). Given this ecotone status, the natural ability for Javan forests to regenerate after some imbalance, whether natural or human-related, has therefore probably long been weak. Climatic forcing during the Pleistocene, as well as ENSO oscillations during the Holocene, may thus have affected Java more acutely than Outer Indonesia. Most of all, human influence at the beginning of the Holocene, which was a period of extensive land use involving patch dynamics characterised by biological diversity (Se´mah et al. 2003), was the greatest where resistance was the least, and it may be no surprise that this insular ecotone was to become Inner Indonesia. Potential vegetation types on Java have been reconstructed according to the conventional criteria of vegetation series mapping (Fig. 8). Evergreen forest is confined to West Java (2,000 mm rainfall). Dry deciduous forest, dominated by teak (Tectona grandis), occurs potentially only in East Java where rainfall 1,000 m a.s.l.), 2 evergreen rain forest, 3 semi-evergreen rain forest, 4 seasonal montane forest (>1,000 m a.s.l.), 5 dry deciduous forest and 6
moist deciduous forest. Moist deciduous forest is also referred to in some texts as ‘monsoon forest’ (Whitmore 1984). The evergreen forest core is fringed by an aureole of semi-evergreen forest (evergreen species mixed with a few deciduous species, 2–4 dry months) on the drier north-facing slopes of the island’s mountains
Learning from biogeographical history and pre-colonial human disturbance
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doubt that its success, and particularly its numerous gregarious stands, is directly linked to two human-related factors: 1. Firstly, its probable introduction around 200 AD by Hindu colonisers. By 1000 AD, it is believed that up to 1.5·106 ha of plots, initially cleared for agriculture, were replaced by teak after exhaustion of soil fertility (Whitten et al. 1996). The recession of forest taxa caused by human deforestation preceding Dutch colonisation has been documented on the volcanic slopes surrounding the Ambarawa swamp in Central Java (Se´mah et al. 1992): in a context of long-term precipitation decline, forest clearance occurred during the sixth century AD, followed by a definitive recession in the early fifteenth century. Teak was thus an early coloniser essentially for reasons of cultural and economic preference by pre-Dutch foreign settlers: teak stands, by filling the gaps already opened in the forest by indigenous shifting cultivators, caused the dynamics of gap rotation to progressively coagulate. 2. Secondly, the ecology of fire has played a major role in the success of teak as its seedlings are both fireresistant and grazing-resistant. If fire has probably been used for at least the last 1 m.y. (Se´mah 1986; Swisher et al. 1994), teak as a dominant species is definitely the result of at least two millennia of deliberate refinement through fire (refinement: forestry term referring to assistance in the survival of trees of a target species by selective removal of others). Furthermore, the outward spreading roots, high water uptake and shade given by teak trees after ca. 5 years affords them supremacy over competing woody species—a natural form of liberation (forestry term describing the freeing of a desired tree from competition by increasing light and reducing root competition). In sum, the Dutch apparently arrived after 1600 AD on an island where the estimated population was 3.4 million (Reid 1984) and teak was already dominant. Teak planting has constituted up to this day ca. 90% of the total Javanese timber harvest, but the establishment of Dutch plantations was merely an additional, if brutal, increment in the longer-term process of moist deciduous refinement. Finally, the average upper limit of occurrence of all the dominant forest types (evergreen, dry and moist deciduous) is 1,200 m a.s.l. Teak itself does not prosper much above 1,000 m. The elevation band between sea level and 1,200 m corresponds to sedimentary plateaux accreted during Cenozoic plate subduction and is historically that which has suffered most from indigenous, colonial and post-colonial deforestation. The limestone plateaux (Gunung Sewu, Bojonegor, Blora), with shallow soils and presumably more stunted trees, were the first to be entirely clear-felled (Lombard 1974). Except in Central Java the high volcanoes had remained relatively unscathed, so that the current distribution of natural forests is highly skewed in favour of montane types.
Learning from a colonial history of timber mining Records of past deforestation on Java prior to 1,800 are meagre (Lombard 1974; Brookfield 1997). The kingdoms of Mojopahit (fourteenth century AD) and Mataram (seventeenth century AD), were major periods of forest colonisation involving permanent agricultural settlement in large clearings. As in Europe, this developed under the impetus of monastic influence. Java’s history of land use since the early nineteenth century, in contrast, has been described extensively (Raffles 1817; Nibbering 1991; Palte 1984, 1989; Peluso 1992; Whitten et al. 1996). However, the main focus being on timber as an economic resource, the collateral impacts of deforestation such as erosion and risk enhancement have rarely been addressed in detail. The population of Java was 4.6 million in 1815 (Raffles 1817). Since its creation in 1602, the East Indies Company (Dutch acronym: VOC) had been conducting mercantile politics but direct land cover disturbance was limited to a few mountain slopes covered by coffee plantations in West Java. After 1810, land cover change in the uplands was not a gradual clearing process but occurred in four main steps summarised in Table 1. The three major stages are reflected in the spectacular progress of river deltas around Java (Fig. 9). After peaking between 1897 and 1937 (22,000 km2 removed), deforestation brought natural forest cover down to 23% in 1939, 11% by 1973 (Donner 1987) and 7% of the surface area (0.96·106 ha) in 1990 (FAO 1990). As a result, very few natural forest stands survive anywhere in Java (Fig. 10) even though it remains difficult to track precisely which areas, forest types and altitudinal zones suffered most (Durand 1989). The Konto river catchment is one of the better documented, where only 7% of the forest has remained undisturbed due to its remoteness, but where the remaining 93% show stigma of long-term human disturbance with impacts on soil erosion and sediment budgets (Smiet 1992). Awareness of the need for soil conservation appeared only at the end of the colonial period, under pressure from the sugar industry. Due to a decline of canal irrigation water caused by deforestation and reduced river discharge, the need for watershed management by reforestation (protection forests) was acknowledged in the Forest Law of 1920 (Smiet 1990). Reforestation of the uplands therefore initially occurred as a consequence of ecological stress experienced in the lowland sawah ecosystems. Fast-growing, non-native tropical pines (Agathis) were planted mostly as protection forests on the steeper and wetter south-facing slopes of the volcanoes as a soil conservation measure. These forests in the late twentieth century have been the main source of conflict (the ‘disputed lands’) between the state and local communities, although predominantly for the forest land rather than the trees themselves. An Indonesian Regreening Programme began in the early 1970s under government control, involving the planting of further protection forests and perennial crops on slopes, the
construction of check dams outside state forests, and of Sabo dams on the more active volcanoes to check lahars. Regreening has also been a focus of conflict (Peluso 1992).
Destruction of 200,000 ha of forest, accelerated soil erosion
Indigenous agroforestry: the fingerprint of an environment inextricably linked to human disturbance
Note: compiled from Raffles (1817), Junghuhn (1854), Nibbering (1991), Durand (1989), Hoek (1992), Peluso (1992) and Sevin (2001)
Deforestation (300,000 ha) of east Central and West Java (Kawah ijen, Kelt, Preanger,...) Environmental consequences (based on written eyewitness reports and archives)
Flight of refugees to thinly populated mountains Deforestation volcanoes in Central Java: Dieng, Sumbing, Sindoro, Merbabu Socio-economic consequences
Intensification of sawah ecosystems Continued clearing of Dieng, Sumbing, Sindoro, Merbabu
Ruin of land management systems
Lands commandeered for commodity crops and food in support of WWII effort
1874 Agrarian Law: privateers extend coffee belt into uplands and sugar crops in sawah and deltas New road and railway cuttings State-run mercantilism commandeers 20% of best village land for cash crops and imposes 2 months per year of forced labour Continued retreat to volcanoes New taxes and statute labour laws Official policy
Raffles interregnum and War of Java (1811–1830)
Historical periods Events and impacts
Table 1 Periodisation of colonial impacts on Javan land cover
Compulsory cultivation system (CCS, or cultuurstelsel) (1830–1915)
Corporate plantation system (CPS) (1880–1930)
Japanese occupation (1942–1945)
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The blanket term ‘agroforestry’ covers a multitude of categories, the nearly extinct ladang being the indigenous prototype. Involving the fallowing of natural trees, it must be distinguished from the tumpangsari system, which was introduced from Burma (taungya system) by the Dutch in 1873 and involved the fallowing of planted trees in addition to rotational cropping. It has since the 1970s evolved into a varyingly successful form of social forestry. The penghijauan system, also a Forestry Service introduction, appeared as part of the post-colonial regreening policy, with intercropping of annuals and short-lived perennials. Finally home gardens, ubiquitous around villages, represent a diverse intergrowth of tree and/or agricultural, and forage and/or green manure crops. The first official record of Javan home gardens defined as agroforestry systems dates back to a charter of 840 AD (Soemarwoto and Soemarwoto 1984). The aspect of man-made forests (talun-kebun, literally: perennial-annual crops) of such garden compounds, even in sawah areas, as a persistent leitmotiv in the landscape, probably reflects how ingrained the culture of agroforestry is through its many derivatives and adaptations to increasing population densities and a market economy (Soemarwoto 1984). The upshot is that the multiple forms of agroforestry probably make it impossible to treat the botanical heterogeneity of past Javan forest vegetation as natural (Michon et al. 1983). Agroforests were until recently viewed by western forestry engineers as a primitive, predomestication stage of selected forest trees. New findings have shown instead that they represent a highly sophisticated domestication of entire forest ecosystems with a bias towards multi-purpose trees through a process of long-term refining (Michon and Foresta 1997). Case studies have shown it is possible to find up to 250 cultivated species (not counting varieties) on the territories of single hillside villages of West Java (Abdullah and Isnawan 1980). Trees are subjected to indigenous horticultural techniques, designed to shorten the period of improductivity and increase the growth rate of fruit, which appear to have evolved over millenia rather than years or centuries. It would thus be too simplistic to reduce the colonial history of Javan forests to a case of ruthless ravaging by the Dutch of virgin ecosystems that an environmentally aware indigenous society was engaged in the noble act of preserving. Conflict was over the political control of forest as a resource (Peluso 1992), whether to claim the trees themselves or the land for agriculture, not over forest protection for moral, aesthetic or spiritual reasons as we
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N
Java Sea 0
4 km Cim
anu
kR
.
INDRAMAYU 1857 1917 1946 1974 Rambutan R.
SINDANG
Fig. 9 Growth of the Cimanuk delta, north Java, during and since the colonial period (after Hehanussa et al. 1975). Given the rapid response of sedimentary systems to recent and well constrained land degradation events (cf. Figs. 4, 5), progress due to increased sediment discharge between 1857 and 1917 is clearly correlated here to the compulsory cultivation system (CCS) period (Table 1), while the 1946 position of the coastline probably reflects further build-up caused by the CPS and maybe also the Japanese occupation. Deltas of Central and East Java recorded equivalent or higher rates of progradation. Thick black lines indicate rivers (some channelised)
see in modern environmental campaigning. In the Old World, for instance in Medieval England, the word ‘Forest’ (with a capital F) was primarily a land of deer, not a land of trees: Forests could be wooded, but not necessarily so (Rackham 1986). The same seems to apply to Javan forests (Lombard 1974), where late into the nineteenth century big game hunting was an important pastime among the indigenous nobility and the colonial aristocracy.
The forest is therefore, in most cultures, a resource, not a place of recreation where trees are valued as an antidote to urban lifestyles. Much evidence exists on the negative connotations of forest in Javanese mentality (Lombard 1974; Whitten et al. 1996). Forest on Java does not have a high cultural value, so it is debatable whether home gardens, for instance, which may have represented an indigenous resource pool and at times a last bastion of economic privacy and resistance against Dutch hegemony (Table 1), should in any way be viewed as an emblem of conscious ecological conservation. In summary, it seems that the Dutch and Javanese unwittingly shared a common enemy: natural forests. As a proof of that, to this day the relict natural forests of Mts Halimun and Slamet have faced lower attrition rates than those at lower elevations partly due to inaccessibility, but mostly due to fear and legend. As such they have retained higher than average levels of faunistic biodiversity. With something that can be harvested almost daily for household subsistance or for cash, the total production of agroforestry is estimated to be higher and less labour-intensive and capital-intensive (no chemical fertilisers or pesticides) than sawah systems. Crucially, however, agroforestry has never been regarded by governing establishments as a rational use of land and labour, and hence never received any support. Self-sufficiency in agriculture is by nature contrary to the reinforcement of the State, and forest-dependent communities lose more than they gain from centralised state control over forests, whether reserved or plantations (Blaikie 1985): the colonial and post-colonial history of Java is a vindication of this. Population, transmigration and deforestation
Fig. 10 Natural forest cover on Java in 1891, 1963 and 1987 (after Whitten et al. 1996). Dramatic recession and fragmentation have occurred in less than one century. Timber plantations and reforestation schemes, however, are not represented but would also count as woodland. These maps thus mostly reflect the threat of deforestation to wildlife habitats and biodiversity rather than to geomorphic stability. Patches of natural forest along the island’s axis coincide with areas on volcanoes sensitive to volcanic hazards, which themselves are a source of natural stability for forest vegetation
By the middle of the twentieth century, about 107 ha of forest, or some 80% of its original area in Java, had been converted to agricultural land (Smiet 1990). At the same time, the population was multiplied by ten in 130 years (1815–1945). The correlation between population density and forest clearing is therefore evident and the idea advocating the conquest of new arable land as a provider of economic welfare has been widely used in the twentieth century for justifying the politics of Transmigration, i.e. the organised rural colonisation and settlement of Outer Indonesia by 1.7 million Javanese farmers in the decade 1971–1980, as part of a state-sponsored policy to reduce population pressure on Java and its environment (Sevin 2001). However, fundamental to understanding the current conquest of the volcanoes as the last frontier of the Javan rural environment is the backlash of the settlement policy, which generated a return flow of at least 0.5 million after 1980. Rather than being reabsorbed into the rural web, the returning migrants settled in Jakarta (Repetto 1986). The urban population of Java has since been growing twice as fast as the rural, so it is ironic that
97
the current deforestation of Javan volcanoes is partly an indirect consequence of the failed Transmigration policy, which was precisely designed to relax stresses on the economy and environment of Inner Indonesia. This phenomenon comes as an overprint on the longer-term decline in labour use for paddy cultivation since the colonial period, which has generated a surplus of landless farming labourers that the rice sector is no longer able to absorb (Repetto 1986), and who must therefore seek a livelihood elsewhere. By targeting the volcanoes, which dominate the geomorphic metabolism of the island, the process of agricultural involution in Java analysed by Geertz (1963) has probably reached in the last 5 years a point of no return. Population growth and high rural population densities are not, however, sufficient to explain the recurrent process of forest clearing. It has in particular been debated whether the Regreening Program, involving plantation forests, has not simply continued the CCS (Table 1) by transposing it to the uplands. Restricting access to land increases population pressure without really avoiding encroachment by marginal farmers, conflict with the authorities, and social unrest (Peluso 1992). It seems, therefore, that post-independence Java has continued to fulfil the prophecy of agricultural involution (Geertz 1963): farmers are having to evolve ever more intensive forms of agriculture while momentum for developing non-farm employment through the promotion of indigenous entrepreneurship in craft and industry is minimal (Repetto 1986).
Disorder in the Javan landscape: synthesis and perspective Knowledge of pre-disturbance states on Java is limited because few undisturbed analogues have survived. The long-term perspective given by the foregoing overview confirms that the current situation of accelerated environmental change on volcanoes has no clear-cut analogue in the past. Discriminating the frequencies of human impacts from the periodicities of natural disturbance regimes is made difficult by the fact that highmagnitude, externally driven natural processes involving slope and river channel instability occur episodically even in the intensively managed Javan agro-ecosystems of today. The high-energy Javan environment is a system in which sediment turnover is rapid and where past geomorphological scars either heal rapidly or are soon destroyed by younger events. The ‘‘normal’’ state of nature on Java is to be recovering from the last disaster, not equilibrium and repose. Given this chronic state of disequilibrium, our short-term data is confirmed by the longer-term evidence that human impacts and natural phenomena are often inextricably linked, humans being opportunistic in their attitudes to natural variability: El-Nin˜o-related fires are used to expand upland agriculture; juvenile volcanic debris are soon co-opted to agricultural land; prograding deltas, supplied by
sediment loads sourced by soil erosion in the hinterland, are developed into polders; river channel banks are deliberately eroded by farmers to extend agricultural land in floodplains (a practice called ngagugur: Diemont et al. 1991). The implication is that palaeoenvironmental research on Java is faced with a chicken and egg problem, as any sedimentary archive (debris flow deposit, landslide scar, etc.), although generally recognisable on the basis of diagnostic criteria, cannot be unequivocally attributed either to a natural cause or to a human-related disturbance. Studying land cover changes in the Late Glacial and earlier, where charcoal levels are not matched with tell–tale pollen indicators of food crops or weeds, Van der Kaars et al. (2001) have also expressed uncertainty over whether open vegetation around the Rawa Danau swamp (West Java) and the Bandung palaeolake was caused by forest clearance, or whether people occupied the lake shores after vegetation had become more open due to natural fires or climate change. The known impacts of colonial land degradation were soil erosion, increased river suspended sediment loads, reduced dry season baseflow and rainy season floods. Towards the end of the CPS period (Table 1), lowland farmers expressed complaints of diminished baseflow in Central and East Javan rivers during the dry season. This record clearly agrees with trends (cf. Fig. 6) detected since 1997 by our own study of the Konto river. Although high evaporation in evergreen forests may dampen discharge potential, changes in land use other than forest/crop ratios (e.g. urbanisation) may change runoff coefficients (e.g. Bruijnzeel 1982; van der Linden 1983), and catchment size should control hydrological behaviour, the generality of reduced river discharge irrespective of catchment size clearly confirms the fundamental role of forest cover on Javan volcanoes as a factor of infiltration and delayed supply of river flow by water tables during the dry season. Our characterisation of environmental change in the last 10 years reveals that changes occurring as a consequence of periodic (e.g. ENSO) rather than exceptional external forcing factors can be pushed over critical thresholds by human design. Ensuing changes attain magnitudes that are not commensurate with the magnitude of the initial triggering cause. Palaeoenvironmental evidence of a vegetation change, or the onset of an erosional episode, may not necessarily imply a major change in climate, land use or other forcing factors, but merely critical threshold breaching of an unstable system in response to a small, short-term perturbation such as fire, a severe storm or a major volcanic hazard. This is an expression of nonlinearity in natural systems (Phillips 2003) that has remained elusive in the proxy analysis of palaeoenvironments, where change has overwhelmingly tended to be interpreted in terms of external forcing within stable systems rather than nonlinear bifurcation within unstable systems. Consequently, in man-managed ecosystems of the past, it remains difficult to unravel linearity from nonlinearity unless the natural and human (e.g. social, economic) settings are equally well
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ENGLAND: Time (years) 3000 BC 2000 100
1000
1000
0
2000 AD
Cultivated land (sawah, tegal)
% of total land area
documented. This close link between natural factors of environmental change and humans immediately amplifying a disturbance to their own advantage is probably even more true in the more distant past when the technical means to disrupt natural balances were limited: cultivation of forest land probably made most progress in the wake of ENSO-related fires, and permanent teak planting took advantage of existing swidden clearings. Awareness of such problems of interpretation of the environmental record is fundamental to ensuring that what we learn from the past is not just a matter of arbitrary perception or prescriptive prejudgement of what is or is not disorder in the landscape. The basic difference between natural and man-made environmental disturbances in the long term is that natural disturbances essentially have local impacts (e.g. a lahar, a pyroclastic flow, a flood, a forest fire; ash fall will cover wider areas but is beneficial to agriculture and presents a limited risk to human life and property). In contrast, human transformations can be designed and organised in a systematic way to impact widely upon a vast territory, as clearly illustrated by four centuries of Dutch and Indonesian resource mining. Traditional shifting cultivation, as a form of local and transient impact on the land cover, mimics the local impacts of natural instability. A study (1926–1933) apparently never repeated (cited in Whitmore 1984) involved clearing small (0.1 ha) gaps in primary forest on Mount Gede in West Java. It was shown that such ladang were rapidly recolonised by surviving young individuals of primary forest trees. Meanwhile, in larger gaps of 0.2–0.3 ha, which may represent a critical threshold between the ladang (better suited to maintaining longterm ecosystem steady states) and clear-felling, the primary forest trees were replaced by a dense growth of secondary forest pioneers. This example shows the importance of thresholds in impacts on botanical systems. The unprecedented problem generated by deforestation of the volcanoes is, specifically, that due to their topographic supremacy and position on the island’s drainage divide, a small or local change on any of them may provoke regional repercussions out of proportion with the size of the initial disturbance. An interesting perspective to this history of deforestation is that the state of land cover attained on Java today is similar to that of England (Fig. 11), where the decline of wildwood (i.e. natural woodland unaffected by Neolithic or later civilisation) over the last 5,000 years is well documented (Rackham 1986): 80% of the original forest was lost by 2000 BP, falling to 1000 m a.s.l.) Teak forest
0 1600
1700
1800
4 1900
Non-teak plantation forest
1990
JAVA: Time (years AD) Fig. 11 Decrease of forest area and land use changes on Java, 1600–1990, and in England in the last 3,000 years (after Smiet 1990 and Whitten et al. 1996). Dashed line refers to England, other curves to Java. 1 Roman invasion, 2 increase due to growth of secondary woodlands, 3 Domesday survey and 4 beginning of woodland planting. The levels of natural forest decline are similar for these territories of ca. 130,000 km2, but in Java decline occurred ca. eight times faster. Lowland forest has suffered most, teak forest has been maintained by management, while montane forest, the last frontier of colonisation on Java, has survived relatively better due to remoteness, impracticalities of agricultural development and superstitious avoidance
geomorphological and sedimentological impacts is comparatively greater in England because the Javan landscape has a greater capacity to adjust to brutal and sometimes radical changes following a great disturbance. Large-scale volcanic eruptions affect the regional climate, destroy the surrounding vegetation and increase river sediment loads for years to decades. With >5070·106 m3 of ash deposited across Java during the last 100 years, however, andesitic volcanism also boosts soil fertility and the vegetation rapidly regrows in the warm humid environment. Meanwhile, soil erosion in England operates at the expense of a non-renewable stock of relict superficial deposits (loess, etc.) inherited from the ice ages or earlier. With its rapid sediment turnover and dynamic slopes and river channels, the geomorphic metabolism of Java is more spectacular and exposes the population locally to much greater risk, but it has sustained far greater numbers of people. With the widespread conservatories of engineered biodiversity in the form of home gardens, it is also debatable whether the overall impact of deforestation on Javan ecosystems as human lifesupport systems is more threatening than in the English context. Historically, English society found outlets to domestic problems relating to the sustainability of resources through colonisation and emigration. The Transmigration programme to Outer Indonesia, already practiced during Dutch rule, is a similar response to the problems of Inner Indonesia. This, however, has now come to an end due to strenuous resistance by host populations to ‘‘Javanisation’’.
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So, in the twenty-first century the last frontier of Inner Indonesia lies within Java itself.
Conclusion Javanese society has known nothing but restricted forest access imposed by the Dutch, the Japanese and its own government. Java’s key non-renewable resources are its oil and its volcanoes. Macroeconomic prosperity comes from the oil wealth, situated offshore, but this fluctuates with global oil crises. In the early 1980s, an oil crisis similar to the Reformation occurred, but the Transmigration policy was still an outlet that indirectly preserved the Javan highland environment from abrupt deforestation. Considering the fundamental function of the volcanoes in the topographic configuration and hydrogeomorphic metabolism of the island, it is unlikely that the ongoing deforestation is just another iteration in the long list of cumulative impacts that have already scarred the island. The volcanoes represent a small fraction of the land area and of the remaining forest, but the final blow that would consist in destroying it is likely to bring about systemic change out of all proportion with the magnitude and extent of the disturbance. The prospect of treeless volcanoes implies that volcanic hazards are no longer mitigated by the friction of trees, and maximised runoff coefficients increase the risk of flash floods and soil erosion. The systemic consequences of this extreme situation are that the life span of dammed reservoirs, which did not exist at the time of previous (colonial) land degradation crises, is dramatically curtailed. Their purpose of hydrological regulation and water storage is hence defeated. Furthermore, sediment storage in these man-made reservoirs causes a lasting reduction in sediment delivery to deltas, so that coastal erosion can be expected despite increased sediment yield from the catchments. We learn from the Javanese past that cumulative causation through time has damaged but not irreversibly disrupted the resilience of the Javan environment. However, its paddy agro-ecosystem is intrinsically more resilient (Geertz 1963) than its upland ecosytems. This may explain why it has absorbed so many iterations of abrupt land cover change, land degradation and agricultural intensification for so long. Our study has provided some baseline insight into the endemic instability of the Javan environment and hence the inappropriateness of envisaging environmental management policies based on assumptions of steady-state equilibria. Knowing from the past that the volcanoes have never endured large-scale deforestation is critical to our understanding of current events. However, what we can least predict or anticipate based on past knowledge is environmental risk to human life and property given that population growth and human occupation of vulnerable sites (steep volcano slopes, floodplains) has attained unprecedented levels. In this no-analogue situation, this is where the future is most uncertain.
Biosketches Dr. Franck Lavigne: Reader in Geography, University of Paris 1, specialises in natural hazards and environmental risks in volcanic settings. After working on lahars on Mount Merapi, he has extended his field research to quantifying hydrological and erosional processes on the Javan volcanoes in relation with recent deforestation. Dr. Yanni Gunnell: Reader in Physical Geography, University of Paris 7, and member of the Institut Universitaire de France. He works on bioclimatology, soil science, quantifying past erosion and sediment transfer rates, and studies human impacts on forest and water resources in the Tropics. Aknowledgements The authors thank the students who contributed to field data acquisition and processing: M. Boun Heng, P. Texier, E. Guyomarc’h, M. Chenet. We are also grateful to our Indonesian colleagues for their help, in particular Prof. Sutikno (University Gadjah Mada) and Ir. Sumaryono (Sabo Research Center) and thank the Centre National d’Etudes Spatiales (CNES) and Spot Image for affording data at discount rates. John Dearing, Simon Haberle and an anonymous reviewer provided thoughtful reviews of the manuscript.
References Abdoellah OS, Isnawan HH (1980) Effect of culture on home garden structure. In: Furtado JI (ed) Tropical ecology and development. International Society for Tropical Ecology, Kuala Lumpur Backer CAB, Backhuizen van den Brink RC (1963) Flora of Java. Noordhoff, Groningen Beuning KRM (1996) Modern pollen rain, vegetation and climate in lowland East Java, Indonesia. Modern Quaternary Res Southeast Asia 14:1–51 Blaikie P (1985) The political economy of soil erosion in developing countries. Longman, London Boun Heng M, Lavigne F, Texier P (2004) Erosion, sediment transport and reservoir sedimentation in the upper drainage basin of the Konto River, East Java. In: Hu C, Tan Y (ed) Indonesia Proceedings of the ninth international symposium on River Sedimentation, vol II. Tsinghua University Press, Yichang, pp 606–616 Brookfield H (1997) Landscape history. In: Boomgaard P, Colombijn F, Henley D (eds) Land degradation in the Indonesian region. Paper landscapes—explorations in the environmental history of Indonesia. KITLV Press, Leiden pp 27–59 Bruijnzeel LA (1982) Hydrological and biogeochemical aspects of man-made forests in south-central Java. PhD Thesis, Free University, Amsterdam (unpublished) Chenet M (2003) L’e´rosion sur les volcans de Java : e´tude du massif volcanique Arjuno-Welirang (Java-Est). MSc Thesis, University of Paris 1, Paris (unpublished) Diemont WH, Smiet AC, Nurdin (1991) Re-thinking soil erosion on Java. Netherlands J Agric Sci 39:213–224 Donner W (1987) Land use and environment in Indonesia. University of Hawaii, Honolulu Durand F (1989) L’e´volution du couvert forestier en Indone´sie: histoire et cartographie des grands sous-ensembles re´gionaux. MSc Thesis, University of Paris 7, Paris (unpublished) FAO (1990) Situation and outlook of the forestry sector in Indonesia. FAO, Jakarta Geertz C (1963) Agricultural involution: the process of ecological change in Indonesia. University of Chicago Press, Chicago
100 Gillis M (1988) Indonesia: public policies, resource management, and the tropical forest. In: Repetto R, Gillis M (eds) Public policies and misuse of forest resources, Cambridge University Press, Cambridge pp 43–113 Guyomarc’h E (2003) L’e´rosion des hautes terres agricoles a` Java: la crise mone´taire de 1998 renforce la pression agricole sur les volcans. MSc Thesis, University of Paris 7, Paris (unpublished) Hehanussa PE, Hadiwisastra S, Djoehanah S (1975) Sedimentasi delta baru Cimanuk (Sedimentation of the Cimanuk new delta). Lembaga Geologi dan Pertambangan Nasional, Bandung (unpublished) Hoek A, van den (1992) Planning as a learning process. A strategy for planning land use programmes at local level with special reference to the upland of Java. Imprint, Islamabad Junghuhn F (1854) Java, zijne gedaante, zijn plantetooi en inwendie bouw, Amsterdam (unpublished) Lavigne F, Hadisantono R, Surmayadi M, Surono Flohic F, Geyer F (2005) The November 2002 eruption of the Papandayan volcano (Indonesia): direct and induced hazards, with emphasis on lahars. Zeitschrift fu¨r Geomorphologie 140:151–165 Karmono (1980) Discharge and sediment yield from the Serayu River. Gadjah Mada University, Faculty of Geography, Yogyakarta (unpublished) Lombard D (1974) La vision de la foreˆt a` Java (Indone´sie). E´tudes rurales 53–56:473–485 Michon G, Foresta H (1997) Agroforests: pre-domestication of forest trees or true domestication of forest ecosystems? Netherlands J Agric Sci 45:4–13 Michon G, Bompard J, Hecketsweiler P, Ducatillon C (1983) Tropical forest agricultural analysis as applied to agroforests in the humid tropics: the example of traditional village agroforests in West Java. Agrofor Syst 1:117–129 Nibbering JW (1991) Hoeing the hills: stress and resilience in an upland farming system in Java. PhD Thesis, Australian National University, Canberra (unpublished) Nibbering JW (1997) Upland cultivation and soil conservation in limestone regions on Java’s south coast. Three historical cases. In: Boomgaard P, Colombijn F, Henley D (eds) Paper landscapes—explorations in the environmental history of Indonesia. KITLV Press, Leiden pp 153–183 Palte JGL (1984) The development of Java’s rural uplands in response to population growth—an introductory essay in historical perspective. UGM Yogyakarta and State University of Utrecht, Utrecht Palte JGL (1989) Upland farming on Java, Indonesia. PhD Thesis, State University of Utrecht, Utrecht (unpublished) Peluso NL (1992) Rich forests, poor people: resource control and resistance in Java. University of California Press, Berkeley Phillips JD (2003) Sources of nonlinearity and complexity in geomorphic systems. Prog Phys Geogr 27:1–23 Rackham O (1986) The history of the Countryside. Weidenfeld and Nicholson, London Raffles TS (1817) The history of Java. London; reedited in 1982, Oxford University Press, Oxford, 2 vols Reid A (1984) The precolonial economy of Indonesia. Bulle Indone Econ Stud 20:151–167 Repetto R (1986) Soil loss and population pressure on Java. Ambio 15:14–18
Ruthenberg H (1980) Farming systems in the Tropics. 3rd edn. Clarendon, Oxford Se´mah. A.-M. (1986) Le milieu naturel lors du premier peuplement de Java. PhD Thesis, University of Provence II, Marseille, 2 vols (unpublished) Se´mah AM, Se´mah F, Guillot C, Djubiantono T, Fournier M (1992) E´tude de la se´dimentation pollinique durant les quatre derniers mille´naires dans le bassin d’Ambarawa (Java Central, Indone´sie) - Mise en e´vidence des premiers de´frichements. C RAcad Sci, Paris, II. 315:903–908 Se´mah F, Se´mah AM, Simanjuntak HT (2003) Recent advances about the central and eastern Java archaeological record: a contribution to the insular southeast Asian prehistory (sic). In: Mercader J (ed) Under the canopy: the archaeology of tropical rainforests, Rutgers University Press, New Brunswick pp 161– 199 Sevin O (2001) Migrations, colonisation agricole et terres neuves en Indone´sie. CRET et DYMSET, Coll. Iˆles et Archipels, Bordeaux, 28, 2 tomes Smiet AC (1990) Forest ecology on Java: conversion and usage in historical perspective. J Trop For Sci 2:286–302 Smiet AC (1992) Forest ecology on Java: human impact and vegetation of montane forest. J Trop Ecol 8:129–152 Soemarwoto O (1984) The talun-kebun system: a modified shifting cultivation in West Java. Environmentalist 4:96–103 Soemarwoto O, Soemarwoto I (1984) The Javanese rural ecosystem. In: Rambo AT, Sajise PE (eds) An introduction to human ecology research on agricultural systems in South East Asia. University of the Philippines, Laguna pp 254–287 Spencer JW, Kirby KJ (1992) An inventory of ancient woodland for England and Wales. Biol Conserv 62:77–93 Suwardi Machfud (1990) Social forestry in disputed upland areas in Java. Social Forestry Network, Network Paper 10b Swisher CC, Curtis GH, Jacob T, Getty AG, Suprijo A, Widiasmoro (1994) Age of the earliest known hominids in Java. Science 263:1118–1121 Texier P (2003) Evaluation des risques hydrologiques dans le bassin-versant amont du Progo, Java-Centre, Indone´sie. MScThesis, University of Paris 7, Paris (unpublished) Van der Kaars S, Penny D, Tibby J, Fluin J, Dam RAC, Suparan P (2001) Late Quaternary palaeoecology, palynology and palaeolimnology of a tropical lowland swamp: Rawa Danau, WestJava, Indonesia. Palaeogeogr Palaeclimatol Palaeoecol 171:185–212 Van der Linden P (1983) Soil erosion in Central-Java (Indonesia)—a comparative study of erosion rates obtained by erosion plots and catchment discharges. Catena Suppl 4:140–160 Van Steenis CGGJ (1961) Axiomas and criteria of vegetatiology with special reference to the tropics. Trop Ecol 2:33–47 Van Steenis CGGJ, Schippers-Lammertse AF (1965) Concise plant-geography of Java. In: Backer CA, van den Brink Backhuizen RC (eds) Flora of Java. Noordhoff, Groningen Whitmore TC (ed) (1981) Wallace’s line and plate tectonics. Clarendon, Oxford Whitmore TC (1984) Tropical Rain Forests of the Far East. 2nd edn. Clarendon, Oxford Whitten T, Soeriaatmadja RE, Afiff SA (1996) The ecology of Java and Bali. Periplus Editions, Dalhousie University
