Cultivation and human impact at 6000 cal yr B.P. in tropical lowland forest at Niah, Sarawak, Malaysian Borneo

Quaternary Research 64 (2005) 460 – 468 www.elsevier.com/locate/yqres

Short Paper

Cultivation and human impact at 6000 cal yr B.P. in tropical lowland forest at Niah, Sarawak, Malaysian Borneo C.O. Hunt a,*, G. Rushworth b a

School of Geography, Archaeology and Palaeoecology, Queen’s University Belfast, Belfast BT7 1 NN, UK Department of Geography and Environmental Science, University of Bradford, Bradford BD7 1 DP, UK

b

Received 28 February 2005 Available online 12 October 2005

Abstract This paper describes palynological evidence for what appears to be comparatively large-scale human impact in the catchment of the Sungai Niah in the wet tropical lowland swamp forests of Sarawak, Malaysian Borneo close to the Great Cave of Niah. Pollen associated with cleared landscapes and rice cultivation is evident in the sedimentary record from before 6000 cal yr B.P. Human activity seems to have been associated with changes in sedimentary regime, with peat-dominated environments being replaced diachronously by clay-dominated deposition. This may reflect anthropogenic soil erosion in the catchment of the Sungai Niah. D 2005 University of Washington. All rights reserved. Keywords: Holocene; Palynology; Wet tropical forest; Rice farming; Clearance; Sedimentation

Introduction An emerging literature documents Holocene human impact on the wet tropical forest landscapes in Island Southeast Asia. Clearance was early (¨7500 cal yr B.P.) in Sumatra (Maloney, 1985; Flenley, 1988). It was also early (¨5000 cal yr B.P.) in Irian Jaya (Haberle et al., 1991). Significant human impact on Java extends only over the last few hundred years (van der Kaars and van den Bergh, 2004; van der Kaars et al., 2001). There is, as yet, little evidence from the Island of Borneo, although Anshari et al. (2004) tentatively suggest Holocene human impact ¨3000 yr ago at Lake Sentarum, Kalimantan. In this paper, we describe palynological and sedimentary evidence for comparatively early Holocene human impact in Sarawak, Malaysian Borneo, most probably linked to rice cultivation. This is the first evidence for mid-Holocene human impact in Borneo. The study area The study sites are located within the catchment of the Sungai Niah, close to the limestone massif of the Gunung * Corresponding author. E-mail address: [email protected] (C.O. Hunt).

Subis (N3- 48V E113- 47V). The Gunung Subis contains the Great Cave of Niah, which has yielded the most comprehensive sequence of prehistoric archaeology in the region, including an important FNeolithic_ cemetery (Harrisson, 1958; Barker et al., 2002a,b) containing ¨500 graves and the renowned FDeep Skull_—still, at 42,000 yr, the oldest modern human remains in Southeast Asia. The cave was used intermittently through the Late Pleistocene, and then again during the FNeolithic_ to recent. There appears to have been a gap in use of the cave during the Early Holocene (Barker et al., 2002a). Previous discussion of this site (summarised in Barker et al., 2002a; Doherty et al., 2000) suggests that the FNeolithic_ people who used the Great Cave as a cemetery were pursuing hunter – gatherer lifeways. On isotopic evidence, however, Krigbaum (cited in Barker et al., 2002b: 147) suggested that plant foods consumed by the FNeolithic_ people at Niah were grown in more open environments than those consumed by Fmesolithic_ and Fupper palaeolithic_ groups. Cereal pollen was recently noted in mid-Holocene cemetery sediments in the cave (Hunt and Rushworth, 2005: 469 – 470), but the significance of this observation is, as yet, unclear. The Gunung Subis lies ¨11 km SW from the present coast of the South China Sea. This is part of the Indo-Pacific Warm Pool—and thus part of the warmest seas on Earth, with temperatures averaging ¨28-C (Yan et al., 1992). Tapper

0033-5894/$ - see front matter D 2005 University of Washington. All rights reserved. doi:10.1016/j.yqres.2005.08.010

C.O. Hunt, G. Rushworth / Quaternary Research 64 (2005) 460 – 468

(2002) describes the regional climate. Typically, daily air temperatures are 22-C before dawn, rising to 32-C in the afternoon. Precipitation at Niah is ¨2000 mm yr 1. The coastal location of Niah enhances strong local seasonal variations in climate (Hazebroek and Morshidi, 2001). Climate is modulated by the distinctive seasonal reversal of winds associated with the East Asian and Australian monsoons. El Nin˜o episodes can bring marked and sustained droughts and sometimes fire (Potter, 2002). Closed rainforest of great biodiversity is still present in the lowland in the National Park around the Gunung Subis (Hazebroek and Morshidi, 2001; Pearce, 2004). This includes: seasonal wet swamp forest with abundant Pandanus spp., Octomeles sumatrana and Pterospermum subpeltatum on alluvial clay soils; dry Dipterocarp forest characterised by Dryobalanops lanceolata, Shorea superba and Dipterocarpus caudiferus on low siltstone – sandstone hills; and Elaeocarpus – Lithocarpus-dominated riverine woodland on natural levees beside the Sungai Niah. The limestone of the Gunung Subis carries an unusual and distinctive flora including Gymnostoma nobile (Casuarinaceae), Schefflera spp., Ficus spp. and Podocarpus confertus (Pearce, 2004). Closer to the coast are remnant mangrove forests dominated by Bruguiera (0.5 –5 km from the coast) and then a Nypa-dominated zone immediately behind the sandy coastal barrier, which here is dominated by Casuarina (personal observation). Large areas outside the National Park have, however, been cleared in recent years for oil-palm plantation agriculture. Methods The work reported here was done to provide landscape context for the ongoing re-investigation of the archaeology of the Great Cave (Barker et al., 2002a,b). The lowland around the karst towers of the Gunung Subis is densely covered with alluvial and swamp forest (Pearce, 2004). Topography in these forests is difficult to resolve on the ground since visibility is rarely more than 20 m. It was thought, at the outset of this investigation, that perennially wet sites would give better conditions for pollen preservation than would be available on sites more prone to drying out. Local informants were, therefore, asked to suggest marshy areas for investigation. Two areas, one close to the cave of Gan Kira and the other near the longhouse at Kampong Irang, were chosen for initial investigation because they were reported by the informants to be exceptionally wet and flood-prone. Within these generally wet and flood-prone areas, drilling sites were chosen by the late B.K. Maloney because they had vegetation which he regarded as of Fwetter_ aspect than that covering most of the alluvial lowland around the Gunung Subis. It was impossible to obtain GPS plots beneath the dense forest canopy, so the positions (Fig. 1) were approximated by tape and compass survey. Initial coring was carried out in September 2001 and a second core was taken from the Gan Kira site in September 2002. A clay-cutting Edelmann head was used to break through superficial tough clays at Gan Kira, and a modified Livingstone

461

Figure 1. Location of the study sites and of the Great Cave of Niah. Limestone massifs are shaded.

corer of Aberystwyth pattern was then used to collect cores from depths below 1 m at that site. At Kampong Irang, the Livingstone corer was used to collect the entire profile. Cores were wrapped in aluminium foil and polythene and refrigerated within hours of collection. Samples were prepared for palynology by the method of Hunt (1985)—disaggregation by boiling in 5% potassium hydroxide solution, sieving on 6-Am nylon mesh to remove solutes and fines, and swirling on a clock-glass to remove silt and sand. Counts of at least 500 pollen grains and spores per sample were made where possible, together with all other palynomorphs encountered during the pollen counts. The palynofacies of the samples was also established, based on counts of 200 organic particulates classified into the usual groups (pollen and spores, algae, insect-derived material, plant cell walls and cuticle, fungally derived material, thermally mature material, spherules, inertinite) following Hunt and Coles (1988). Of these classes, counts for thermally mature material (microcharcoal: characteristically brown to dark brown in colour and showing traces of cellular organisation typical of wood), carbonaceous spherules and VAMs (vesicular arbuscular mycorrhyza: fungal symbiotes on the roots of plants and thus a useful indicator of eroded soils in water-laid sediments), were included in the pollen diagrams. The data were handled and pollen diagrams constructed in TILIA, TILIAGraph and TGView. The diagrams (Figs. 2 and 3) show all pollen, spores, algae and palynofacies calculated as a percentage of total pollen and spores. AMS and conventional radiocarbon dating with extended counting was carried out at Beta Analytical Inc., Florida, USA. Dates were calibrated using the CALIB programme and the INTCAL98 data set (Stuiver et al., 1998). Results are given in Table 1. In spite of the proximity of sample sites to limestone karst towers, the sediments were extremely acidic, with pH

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Figure 2. Pollen analysis of the Gan Kira core.

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Figure 3. Pollen analysis of the Kampong Irang core.

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Table 1 Details of radiocarbon dates Core and depth

Lab no.

Material

Pretreatment

Kampong Irang 3.08 m

Beta-193910

Peat

Acid/alkali/acid

Gan Kira 2.87 m

Beta-193908

Wood

Acid/alkali/acid

Gan Kira 3.55 m

Beta-193909

Organic sediment

Acid washes

measured at 3.5– 4.5 in both cores. Therefore, any hard-water effect was assumed to be negligible. Gan Kira This site is located in the gorge-like feature that separates the karst tower containing Gan Kira (the FPainted Cave) from the larger karst tower containing the Great Cave of Niah (Fig. 1). The gorge floor is seasonally flooded and covered with mixed swamp forest, with abundant Pandanus (probably P. basilocularis, which has been recorded from the gorge by Pearce, 2004). The stratigraphy is shown in Figure 2. Dark bluish-grey laminated clays, interpreted as tidal mangrove swamp deposits, pass up into dark brown peaty clays and then about 2 cm of dark brown woody peat, interpreted as back mangrove swamp deposits. The top of the woody peat is charred and this is overlain by a thick clay, pale yellow-grey in colour with strong brown mottles and with streaks of minute charcoal fragments. This is overlain by a very thin litter layer. Three assemblage-biozones may be recognised: Biozone GK-1 –Bruguiera – Ceriops – Sonneratia Characterised by 45 – 75% Bruguiera, with 7 – 22% Ceriops and 2– 7% Sonneratia. Also present are the coastal taxon Casuarina, forest taxa such as Lithocarpus and Elaeocarpus, a few Poaceae and Pteropsida grains and cysts of the freshwater dinocyst genus Saeptodinium. Thermally mature material (microcharcoal) and small carbonaceous spherules are common. This biozone ended shortly before 6480 + 50 –0 cal yr B.P. Biozone GK-2 –Sonneratia – Poaceae – Pteropsida Characterised by falling (6 –57%) Sonneratia, 11 –19% Poaceae and rising (0.5 – 43%) Pteropsida. Also present are Palmae. Cyperaceae and Cystopteris-type have distinct peaks in the upper part of the biozone, as do Saeptodinium and the zygnemataceous algae Spirogyra and Zygnema. Thermally mature material (microcharcoal) and small carbonaceous spherules are common. This biozone started shortly before ¨6480 cal yr B.P. and ended shortly after ¨2350 cal yr B.P. (Table 1). Biozone GK-3 –Pteropsida Characterised by extremely high (22 – 92%) Pteropsida. Polypodiaceae, Gleicheniiaceae and Cystopteris-type are also present. There are few pollen of forest trees or mangroves. Towards the top of the biozone, pollen of Poaceae, Asteraceae and Cyperaceae are present and

Radiocarbon determination Radiometric with extended counting Radiometric with extended counting AMS

14

Radiocarbon age, C yr B.P.

Calibrated age, cal yr B.P. (intercept with 2j)

5160 T 60

6000 (5920) 5850

2350 T 80

2720 (2350) 2290

5710 T 80

6670 (6480) 6310

Saeptodinium cysts, spores of Spirogyra and psilate algal spores (usually associated with the roots of reeds and sedges in standing water) and specimens of the (?) fungal body Concentricystes (common in wet soils) become common. This biozone commenced shortly after ¨2350 cal yr B.P. (Table 1). Kampong Irang This site is c. 300 m from a Penan village, called Kampong Irang by local informants but mapped as Rh. Chang, in the main alluvial wetland adjacent to the Sungai Niah (Fig. 1). The site is a low-lying area, which floods seasonally and after heavy rainfall. The vegetation is almost completely dominated by Pandanus, some of considerable stature. The stratigraphy is shown in Figure 3. Dark grey highly organic laminated clays, interpreted as tidal mangrove swamp deposits, pass up into dark brown peaty clays and then dark brown woody peat, interpreted as back mangrove swamp deposits. The top of the woody peat is charred and this is overlain by a thick clay, pale grey in colour with strong brown mottles and with occasional charcoal fragments. This is overlain by a very thin litter layer. Two biozones may be distinguished: KI-1– Bruguiera– Ceriops – Casuarina Characterised by very high Bruguiera (52 – 66%), and significant Casuarina (5 –26%) and Ceriops (4 –29%). Palmae and Elaeocarpus are usually present. The marine dinocyst Lingulodinium sp. is recorded near the base of the biozone, and the freshwater dinocyst Saeptodinium is noted higher in the biozone. Small carbonaceous spherules and thermally mature material (microcharcoal) are common. This biozone ended shortly before 5920 cal yr B.P. (Table 1). KI-2– Pteropsida Characterised by extremely high Pteropsida (24 –85%), with some Casuarina and a little Poaceae, Cyperaceae and Palmae usually present. Cereal-sized Poaceae pollen is present in two samples. The biozone commenced shortly before 5920 cal yr B.P. (Table 1). Discussion Biozones GK-1 and KI-1 are interpreted as having been laid down in a relatively undisturbed back-mangrove swamp dominated by Bruguiera and Ceriops. A nearby coastal barrier

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is suggested by the relatively abundant Casuarina and Dodonaea (today virtually confined to coastal sandhills in this part of Sarawak), the presence of Myrica (usually also coastal) and the presence of the sand-favouring front mangrove Avicennia. Waning marine influence at Kampong Irang is suggested by the disappearance of the marine dinoflagellate cyst Lingulodinium and the appearance of the freshwater Saeptodinium. Salinities were probably very low throughout GK-1 at Gan Kira since Saeptodinium is known only from fresh and very slightly brackish environments (Hunt et al., 1985). The abundant thermally mature material and spherules point to frequent fires, though it is unclear whether these are anthropogenic or natural in origin. Fairly large-scale clearance adjacent to Gan Kira around 6480 cal yr B.P. is suggested by the peaks in Poaceae and Cyperaceae and the rise in Pteropsida during GK-2. A similar event is recorded at Kampong Irang at the base of KI-2 close to 5920 cal yr B.P. The presence of unequivocal cereal grains in all aspects similar to modern rice pollen from local traditional agriculture points to these clearances being for rice cultivation. This activity seems to continue until just after 2350 cal yr .B.P. at Gan Kira. The end of this phase is not dated at Kampong Irang, because of the lack of suitable material for dating. The date of the end of the clearance phase at Gan Kira at ¨2350 cal yr B.P. is broadly coincident with a date of 2308 T 35 14C yr B.P. (OxA 11548) for the last burials of the Neolithic cemetery in the Great Cave at Niah (Barker et al., 2002b: 146). Date for the inception of the cemetery in the cave are less clear, but it may be suggested that the Neolithic funerary activity in the Great Cave is a manifestation of the rice cultivators suggested by the palynological record described here. This observation is significant, since evidence for rice use by the people who constructed the cemetery in the Great Cave is presently confined to a handful of rice impressions in potsherds from the cemetery (Doherty et al., 2000; C. Doherty, personal communication, 2003) and a single pollen analysis (Hunt and Rushworth, 2005). The suggestion of Doherty et al. (2000), that rice farming was not widespread in Sarawak until medieval times, must be re-evaluated in the light of the results described here. The back-mangrove taxa disappear after the clearance events, broadly coincident with an abrupt change in sedimentation style, and the replacement of freshwater peat sedimentation with clays, most probably of alluvial origin. This event appears to be highly diachronous, happening much earlier at Kampong Irang (which is adjacent to a stream with a catchment estimated from DEMs at 25 km2) than in Gan Kira (which has virtually no catchment). The continued abundance of spherules and thermally mature material after the start of alluvial clay deposition points to repeated fires in the region. Charring of the top of the peat is apparent at the peat/clay transition at both sites and points to local fires. It is hypothesised that widespread clearance and agriculture in the region liberated large quantities of sediment into the river systems. Localised burning of the back-mangrove vegetation was followed by alluvial clay deposition, perhaps starting adjacent to waterways and extending away from them over time.

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The clays deposited in biozones KI-2 and GK-3 are characterised by extremely abundant Pteropsida spores. In the Niah area, open areas such as old fields very quickly become colonised by ferns, most of which (from our observations) have psilate monolete spores similar to those logged here as Pteropsida. Spores of this type are, however, extremely durable (Havinga, 1971) and it is possible that they have survived in conditions inimical to the preservation of, for example, tree pollen or where there are grounds for supposing that parts of the forest are not represented palynologically. This latter issue is particularly important in the lowland forests of Borneo, where components of the rainforest flora are not easy to resolve palynologically—most dipterocarps are virtually invisible palynologically because of low and erratic pollen productivity (e.g., Morley, 2000: Fig. 4.6) and other important groups such as the Lauraceae produce pollen which does not fossilise (Morley, 2000: 57). In this context, the substantial presence in the clays of Spirogyra spores is important, since this alga requires sunlight to produce spores (van Geel, 1976). It is therefore inferred that the clays accumulated in unshaded environments subject to seasonal flooding. Whether these environments were kept open by people is unclear, since deposition of clays with abundant Pteropsida and Spirogyra persist after the end of the recognisable signal for agriculture (grass, weed and Cyperaceae pollen) in both cores. The swamp forest now present on both sites is clearly comparatively recent. Unpublished pollen analyses from the Great Cave by COH suggest that the vegetation there had closed by 500 yr ago. The rising figures for Poaceae, Cyperaceae and Asteraceae near the core-top at both sites may reflect further human interference with the landscape, including renewed rice cultivation, logging and the spread of plantation agriculture, especially in the second half of the last century. Conclusion This research provides evidence that in the vicinity of the Great Cave of Niah, in the wet tropical lowland forest of Sarawak, there was comparatively widespread forest clearance, probably associated with rice cultivation, from ¨6500 cal yr B.P. until ¨2350 cal yr B.P. The clearance seems to have been associated with widespread fires. Disruption of the forest was pervasive enough to trigger large-scale soil erosion, resulting in rapid overwhelming of mangrove-dominated peatswamp by alluvial clays. The end of visible agriculture coincides with the ending of the FNeolithic_ cemetery in the Great Cave. This might be taken to suggest that the cemetery is a manifestation of the agriculturalist’s culture. These findings suggest that it is possible that the hunter – gatherer lifeways reported by early ethnologists in Sarawak reflect a late adaption to wet tropical forest life, rather than the predominant mode of life for much of the Holocene. Finally, in a landscape where surface archaeology is extremely rare, the palynological signal as recorded here may present the most convincing available evidence for prehistoric agricultural activity near the Great Cave. Future work should address the question of whether this is an isolated instance, or a regional phenomenon.

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Acknowledgments This paper is dedicated to the memory of Bernard Maloney, who was to have carried out this work as part of the multidisciplinary Niah Cave Project, funded by the AHRB and Sarawak Museums Service under the leadership of Professors G. W. Barker and D. D. Gilbertson. We thank Edmund Kerui and Michael Bird for assistance with coring and Henry Lamb for the loan of the Livingstone corer. The paper was improved by reviews from Michael Bird and an anonymous referee. NCP contribution no. C. References Anshari, G., Kershaw, A.P., van der Kaars, S., Jacobsen, G., 2004. Environmental change and peatland forest dynamics in the Lake Sentarum area, West Kalimantan, Indonesia. Journal of Quaternary Science 19 (7), 637 – 656. Barker, G., Barton, H., Beavitt, P., Bird, M., Daly, P., Doherty, P., Gilbertson, D., Hunt, C., Krigbaum, J., Lewis, H., Manser, J., McLaren, S., Paz, V., Piper, P., Pyatt, B., Rabett, R., Rose, J., Rushworth, G., Stephens, M., 2002a. Prehistoric foragers and farmers in southeast Asia: renewed investigations at Niah Cave, Sarawak. Proceedings of the Prehistoric Society 68, 147 – 164. Barker, G., Barton, H., Bird, M., Cole, F., Daly, P., Gilbertson, D., Hunt, C., Krigbaum, J., Lampert, C., Lewis, H., Lloyd-Smith, L., Manser, J., McLaren, S., Menotti, F., Paz, V., Piper, P., Pyatt, B., Rabett, R., Reynolds, T., Stephens, M., Thompson, G., Trickett, M., Whittaker, P., 2002b. The Niah Cave Project: the third (2002) season of fieldwork. Sarawak Museum Journal 78, 87 – 177. Doherty, C., Beavitt, P., Kerui, E., 2000. Recent observations of rice temper in pottery from Niah and other sites in Sarawak. In: Bellwood, P., Bowdery, D., Allen, J., Bacus, E., Summerhayes, G. (Eds.), Indo-Pacific Prehistory: The Melaka Papers, vol. 4, pp. 147 – 152. Flenley, J.R., 1988. Palynological evidence for land use changes in South-East Asia. Journal of Biogeography 15 (1), 185 – 197. Haberle, S.G., Hope, G.S., Defrets, Y., 1991. Environmental change in the Baliem Valley, Montane Irian Jaya. Journal of Biogeography 18, 185 – 197. Harrisson, T., 1958. The caves of Niah: a history of prehistory. Sarawak Museum Journal 8 (38 – 39), 367 – 373. Havinga, A.J., 1971. An experimental investigation into the decay of pollen and spores in various soil types. In: Brooks, J., Grant, P.R., Muir, M.D., Van Gijzel, P., Shaw, G. (Eds.), Sporopollenin. Academic, London, pp. 446 – 478. Hazebroek, H.P., Morshidi, A.K.b.A., 2001. National Parks of Sarawak. Natural History Publications, Kota Kinabalu, Sabah.

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