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A temporary palliative or a means of aiding global management
No management would be able to cope with continued exponential growth in global greenhouse gas emissions, or with the large temper ature increases and consequent climatic changes that must inevitably follow after a lag period of still-undetermined length. Cline (1992: 22-26) marshals data suggesting that an eightfold increase in atmospheric CO2 by the year 2250 could create a commitment to a global mean increase of 10.7°C for the central case and 19.3°C for the upper bound. Whatever the reality, it would become so hot that there would be widespread species extinction and large parts of the world would become uninhabitable to the human race. If we assume that there will be a continued march toward such an outcome, then the carbon sequestration capacity of tropical biota becomes no more than a shortlived temporary palliative. If, on the other hand, we assume that fossil fuel outputs can and will be stabilized at some very much lower level, then there is a potentially important role for tropical areas of low population density in the process of amelioration and stabilization.
The high net primary productivity of the tropics might as a whole be enhanced by an increase in atmospheric CO2, although principally where favourable soil and water conditions exist to make greater growth possible, and hypothetically with lower biodiversity. All trees are C3 plants, although their degree of response to increased CO2 differs widely (Fajer and Bazzaz, 1992). However, as an accompaniment to large-scale steps to reduce energy dependence on fossil fuels inefficiently used, both the natural regrowth in cutover areas and planted forests could absorb significant quantities of carbon. R. A. Houghton (1990a, 1990b) shows how a complete halt to all tropical deforestation coupled with massive reforestation could, for a 20-30year period of rapid growth, absorb something like three-quarters of the late-1980s' annual emission due to fossil fuels.
This would not last, for an established forest would, if undisturbed, soon approach neutrality in regard to carbon emission and sequestration. This leads Houghton very boldly, if perhaps not very realistically, to suggest that managed forests, greatly enlarged from the present extent of remaining forest, be developed as an energy source in place of fossil fuel on a rapid regrowth cycle so as to become carbon-neutral. The problems in the way of such a solution are daunting, and he fears, not unreasonably, that "the world may have exceeded its capacity to produce a supply of energy that is both sustainable and renewable" (R. A. Houghton, 1990b: 421). Examining scenarios based on Houghton's findings, Bekkering (1992) however agreed that, although the contribution of reforestation to carbon sequestration is insignificant at present rates of planting, a larger programme could have a significant effect.
Conclusion: A place for managed forestry and agro-forestry?
We therefore have the seeming paradox that both forestry and shifting cultivation, if reconstructed on sound management lines, could be of positive benefit to a world that is bringing its new greenhouse gas emissions under control and seeks means of getting some of the emissions already in the atmosphere down into the biosphere where they will do good rather than harm. In other words, what is anathema to most of the world's conservationists today could, under attainable conditions, become of benefit to the whole global ecosystem and to the economy at the same time.
By themselves, Borneo and the Peninsula do not contain the available area to sequester more than a small part of the total CO2 in the atmosphere. Even so, Borneo has become the locus of an intriguing new development, that of utility companies in developed countries funding managed forestry and plantation forestry so as to offset their own carbon emissions and thus avoid proposed taxation (Vatikiotis, 1994). One company in the United States and the Netherlands Electricity Generating Board are funding the replanting of 3,500 ha in Sabah, and the company that is mediating these efforts has plans to get funding for replanting of 23,000 ha in Borneo as part of a global target of 150,000 ha. Proposals have also been made for international funding of an experimental, managed forestry area in the remaining concessions of the Sabah Foundation, as a design for wider adoption, and for support of the replanting efforts. In addition, there have even been proposals for international funding not to mine the coal underlying one particularly distinctive area of stillinaccessible forest. Although some people question the morality of funding lessprofitable managed forestry in the developing countries so that developedcountry utilities can continue polluting the atmosphere, the new "carbon credits" development might have a future in this region.
Notes
1. To a great degree this chapter discusses considerations affecting South-East Asia as a whole, and even the tropical developing countries as a vhole, rather than just Borneo and the Peninsula. This is necessary if the literature is to be used effectively and if a balanced set of conclusions is to be reached. However, the argument returns to the region in conclusion.
2. The addition of inputs from degradation without clearance, discussed below, would raise this proportion.
3. To write this is not to imply any lack of sincerity on the part of so respected a body as the WRI. However, such bodies do need issues that will bring in financial support from well heeled backers. In North America and Europe it is much easier to find support for combating tropical deforestation than for campaigning to change the energy-intensive lifestyles and economies of the developed countries themselves.
4. Thery(1992: 89) moreover notes that "Perhaps they found it opportune to merge the weight of past emission contributions by the OECD countries and the growing share contributed by the poor countries from the South in one 1987 index."
5. One example, in an "Ecoropa Information Sheet" reprinted in World Rainforest Movement (1992: 2), reads: "Forest burning in Brazil was responsible for about 20% of greenhouse gases released in 1988." Although scientific writers never commit such errors, they are frequently quoted out of context in the media. Asiaweek (25 November 1988), for example, quoted the director of the Goddard Institute for Space Studies on global warming solely in the context of tropical deforestation. This is far from an isolated example.
6. This section draws heavily on Brookfield (1992).
7. Until the late 1980s the carbon effect of shifting cultivation was generally treated as neutral, since regrowth in the fallow period sequesters about the amount of carbon released on clearance, though over a much longer period. However, increasing replacement of shifting cultivation by more permanent farming systems, together with reduction of fallow periods, requires an allowance to be made.
8. These estimates have since been refined by Richards and Flint (1994).
9. R. A. Houghton (1990b: 416) estimated 20 per cent.
10. It is possible to measure CO2 flux from soils in small sample areas enclosed under a cover; no ready means can be envisaged of measuring the flux from a forest.
Droughts, fires, and El Niņo
Greater detail on El Niņo-induced droughts in
Borneo
Conclusions
Agro-climatic zones of Borneo and the Peninsula
The earliest comprehensive attempt to classify the climates of the Indonesian region was that of Mohr (1944) based on the ratio between the mean number of months with over 100 mm precipitation and those with under 60 mm. Using data for each year, this was refined by Schmidt and Ferguson (1951), and later by Fontanel and Chantefort (1978), who defined a month as "dry" when its mean precipitation in millimetres was less than twice its mean temperature in degrees Celsius. On the latter basis no part of Borneo and only the far north-west of the Peninsula have climates with dry seasons. However, using and extrapolating the system of Schmidt and Ferguson, Whitmore (1984: 55) shows quite a broad belt along the eastern and southern coastal regions of Borneo as also experiencing a weak dry season.
A different approach is adopted by Oldeman, Lal, and Muladi (1980), who relate climatic classification to crop water requirements, particularly rice requirements. Such a classification is also useful for indicating periods of possible moisture stress affecting forest growth. We discuss its application to Borneo. They define a wet month as receiving more than 200 mm, but very wet areas, with over 400 mm in at least two consecutive months, are also delineated. Dry months receive less than 100 mm, the critical minimum precipitation needed to exceed potential evapo-transpiration. Using this Indonesia-wide classification and mean monthly rainfall data for 88 stations, Kalimantan is divided into nine zones, from A to E, all except A being subdivided (fig. 8.1). Zone A, with more than nine wet months, covers over 40 per cent of the area, especially the central mountains and the ranges along the Malaysian border. Zone B1, with seven-nine wet months and fewer than two dry months, occupies a further 30 per cent and is the most extensive climatic zone in West Kalimantan. The east and south-east coastal regions are the main locus of drier climates. The driest zones of all, E1 and E2, with fewer than three wet months and up to three dry ones, are in central East Kalimantan, extending inland to include the middle Mahakam basin (Oldeman, Lal, and Muladi, 1980).
Fig. 8.1 Agro-climatic zones of Borneo (Source: Potter, from data described in the text)
Data for 71 stations provided in the Land Capability Classification of Sabah (Thomas, Low, and Hepburn, 1976), plus 40 Sarawak stations drawn from Seal (1958) and Chan (1984), allow the tentative extension of the Kalimantan agro-climatic map through Sabah and Sarawak shown in figure 8.1. Notable in Sabah is the rapid change in rainfall patterns as one moves over the high mountains, with a sharp gradient from A to E zones from west to east across the Cracker range. Totals are quite low over much of this interior plateau, where one station has only a marginally higher mean rainfall than the driest in Borneo - Sangkulirang in East Kalimantan (1,625 mm); however, mean monthly values do not drop below 100 mm (Beaman et al., 1985). The south-east coast is also protected from rain-bearing winds by surrounding high country and is a dry pocket, but exposed coasts receive heavy rain from the north-east monsoon (Lee, 1965; Sham Sani, 1984).1
Inter-annual variability and El Niņo
All data based on mean values obscure inter-annual variation, and this is considerable even in areas classed as almost a-seasonal in the classifications. Fontanel and Chantefort (1978: 23) show that, even over the short period from 1961 to 1971, variability at Pontianak approached 40 per cent, precipitation falling to 2,638 mm in 1965 and rising to 4,912 mm in 1969. At Sandakan in Sabah, where records go back to 1879 (with some gaps), the range of annual precipitation up to 1992 was from 1,459 mm (in the 1914 drought) to 4,330 mm, around a 91-year mean of 3,039 mm (Meteorological Service, Sabah). In the Peninsula, Pekan on the east coast received only 954 mm in 1902, against its mean total of 3,230 mm (Dale, 1959/60).
Not all, but most, of this variability is associated with the El Niņo Southern Oscillation (ENSO) phenomenon and its extremes. Nicholls has noted the very large spatial scale over which ENSO events occur and the amplified rainfall variability found in affected areas (Nicholls and Wong, 1989; Nicholls, 1992, 1993). Although one might expect long dry periods to occur in the lower rainfall areas during El Niņo events, and this is generally the case, surprising anomalies may also occur in the severity and length of the normally weak dry season in areas of much heavier falls.2
However, the incidence of seasons of drought and heavy rain in the Indonesian/Malaysian region frequently correlates poorly with the strength of events as indexed by their accepted signals in the oceanic
Pacific and on the South American coast (Quinn et al., 1978; Quinn, Neal, and Antenuz de Mayolo, 1987; Allen, Brookfield, and Byron, 1989; Brookfield and Allen, 1991). For example, a very major drought in the Indonesian region in 1914 corresponds with only a moderate east Pacific El Niņo
Nor is this all the variability that needs to be taken into account. The magnitude and severity of dry events in wetter parts of the region are sometimes out of phase with those in the more regularly seasonal parts. The year 1965 is a case in point. It produced the strongest dry period signal in the Indonesian/New Guinea region as a whole between 1941 and 1972, but in the main it created only minor problems for agriculture. Yet in a part of normally drought-free West Kalimantan, it was reported to Potter that many people died of starvation as a result of drought and crop failure in that year. The year 1972 was more widely a drought year, and again it was particularly severe in West Kalimantan (Salavsky, 1994).
Droughts in modern
There is a nineteenth-century record of famine, as well as drought, from Java, though the famine events in that wet-rice island are associated principally with close-spaced incidence of drought and heavy rain - of El Niņo preceded or followed by La Nina - and not with drought alone (Brookfield, 1993). The Colonial Reports describe drought in Java and Bali in both the 1850s and 1860s, and there is evidence of a region-wide drought of unusual severity in 1804 (Allen, Brookfield, and Byron, 1989). The explorer von Gaffron reported a persistent drought in 1846 in Kotawaringan, the remote southwesterly section of Central Kalimantan (Pijnappel, 1860), but we are lacking other reports from that year. There were certainly other events, but in the absence of any systematic record they cannot firmly be identified. Continuous rainfall recording began at Jakarta in 1864, but it was not until after the major event of 1877/78 that a countrywide network of rainfall stations was established, as it was also in India after the same disastrous year.
It is now generally recognized that, globally, the El Niņo episode of 1877/78 was the most severe on record before that of 1982/83 (Kiladis and Diaz, 1986; Allen, Brookfield, and Byron, 1989; Brookfield and Allen, 1991). Drought was fierce, prolonged, and very widespread through the tropics and sub-tropics. Millions died in mainland Asia, though not in South-East Asia. The improvement in the record subsequent to this event is enormous. In Indonesia, the network of over 100 stations created in 1878, and mostly recording by 1879, expanded to 551 by 1915 (Boerema, 1917). There was only a more minor improvement in the record of the territories that became Malaysia; these suffered less in 1877/78.
In Indonesia, assemblage of data made possible the first scientific studies of rainfall and drought in 1905 and 1916 for Java (Figee, 1905; Van Bemmelen, 1916), and then over the whole country in the same second decade of the century (Break, 1915; Boerema, 1917). These studies were themselves prompted by new dry events of major order, that of 1902 also prompting two important government inquiries, one on declining welfare in Java as a whole (Onderzoek, 1904-1914) and the other specifically on famine in an area of north Java (Commissie, 1903). Then there was a further major drought in 1914. Thereafter, South-East Asia entered a long period with only short or regionally confined droughts. One young scientist did some important work on the proxy record of tree-rings in teak (Berlage, 1931), which, when he later became a renowned climatologist, played an important part in generating theory about ENSO and the Southern Oscillation (Berlage, 1957). With this exception, however, there seems to have then been a lull in Indonesian drought studies until after 1982/83.
The events accompanying the 1982/83 ENSO episode led to an upsurge in world interest in the phenomenon and its local impacts. In Indonesia the magnitude of the East Kalimantan fire prompted research into the drought/fire nexus (Leighton, 1984; Lennertz and Panzer, 1983; Wirawan, 1984a, 1984b; Malingreau, Stephens, and Fellows, 1985; Leighton and Wirawan, 1986). Work was also under way in Sabah, where large forest fires had occurred as well (Beaman et al., 1985; Woods, 1987, 1989). Follow-up studies were initiated in East Kalimantan by a German group investigating the possibilities of rehabilitating the burned area (Schindele, Thoma, and Panzer, 1989), which included a brief survey of the effects of the 1982/83 event on human populations, a curiously neglected aspect of all earlier work (Mayer, 1989). A Japanese-led team, concentrating on Kutai National Park, examined the fire's impact on soils, vegetation, and primates (Tagawa and Wirawan, 1988). These later studies, not surprisingly, centred almost solely on the effects of the fire rather than of the drought, as did Woods (1989) for Sabah.
Drought and the forests
Most early work on the climatic conditions of rain-forest formation concentrated only on annual mean values (Richards, 1952). By the 1960s there was a better appreciation of the significance of drought. In the Peninsula, a serious 1963 drought, not related to an El Niņo reduced rainfall to only 4080 per cent of mean values (Nieuwolt, 1966). Brünig (1969) demonstrated that even for Sarawak, which on the basis of mean data shows little seasonal variation in rainfall patterns, dry periods of 30 consecutive days below 100 mm can occur more frequently and with stronger seasonal peaks than the monthly totals indicate. Water deficits, with reduced transpiration and growth of forest trees, will occur quite rapidly on certain soil types, especially heath forest soils, soils developed over limestone, and deep peat. Brünig (1977, 1987) feels that some morphological features of lowland rain forests, such as the prevalence of small, thick leaves and bark in upper-storey trees, and phonological features, namely drought-induced fruiting of dipterocarps, all indicate a response to regular dry-period stress. During severe drought these stresses are magnified, even in West Kalimantan and Sarawak.
Whitmore (1984) noted that exceptionally heavy flowering occurred in the Peninsula after the 1963 drought, and again after an event in 1968. Ashton, Givnish, and Appanah (1988: 55) believe that "drought is broadly correlated with mass flowering in peninsular Malaysia and Borneo." They also suggest that El Niņo events trigger mass flowering in dipterocarps and cite evidence that this was indeed the case in many areas throughout Malesia during the events of 1976/ 77 and 1982/83.
Fire and drought
It is now possible to conclude that little of the region, even of Borneo, is immune from drought, and almost none of it under extreme conditions, such as existed in 1982/83. Probably only the montane forests of the interior always experience enough cloud and rain to avoid moisture stress. Closer to the coast, even the forest on Mt Kinabalu was badly affected by the drought of 1982/83. The corollary, given increases everywhere in human populations and in logging activities, is that much of the region is not immune from forest fire either.
This was not, however, appreciated at once. After the great conflagration in East Kalimantan and Sabah during the drought of 1982/83, fire was at first regarded as an unfortunate, but recently added, accompaniment to drought. However, fires occurred again in a limited area of East Kalimantan during the minor drought of 1987 and they were once again widespread during the prolonged El Niņo of 1991-1995, though nowhere approaching the extent of the catastrophe of 1982/83.
Fires, however, are not a new element. Closer examination of the literature has shown that fires broke out in at least parts of East, South, and West Kalimantan during the drought of 1914 (Break, 1915; Rijckmans, 1916; Van der Laan, 1925; Endert, 1927). During the 1972 drought, Chia (1979) has described "very extensive haze" between the months of August and October over Singapore, the Peninsula, Eastern Sumatra, Java, Kalimantan, and Sarawak. He attributed this to "the burning of forest trees by shifting cultivators of the Indonesian islands of Sumatra and Kalimantan." Similar accounts appeared in the New Straits Times (Kuala Lumpur) in October 1972. The descriptions sound very much like the 1991 situation, in which there was a whole range of reasons for the extensive fires. Braak mentions extensive haze or fog accompanying the event of 1902, which could also indicate burning, although thus far no direct evidence has been found. Direct evidence is quoted, however, for the drought of 1846 in Kotawaringan, Central Kalimantan. Von Gaffron, exploring the district for coal and gold, described extensive burning of swamp forest, an area he estimated at almost 600,000 ha, which he believed must have burned for months (Pijuappel, 1860). He made no mention of any human influence, suggesting friction from the dry stems rubbing together. Swamp forest, especially if it is underlain by peat, is susceptible to burning in a very dry period.
Several separate excavations in East Kalimantan have revealed the presence of charcoal at depth. The locations were along an inland road (Goldammer and Seibert, 1989; Goldammer, 1992) and at two other locations, one of them in a kerangas forest (Shimokawa, 1988; Kartawinata, 1993). Some of these were associated with burning coal seams, and dated from 350 to as long ago as 17,710 years before the present. It is clear that fires have been around in many parts of the Borneo forests for a long time. Whereas the prehistoric evidence comes from the east, modern fires have also been reported in West Kalimantan (Break, 1915; Salavsky, 1994). The new factor of increased populations, associated with both agriculture and logging, has greatly increased forest vulnerability to even more widespread burning.
