Vegetation and land-use at Angkor, Cambodia: a dated pollen sequence from the Bakong temple moat.

Vegetation and land-use at Angkor, Cambodia: a dated pollen sequence from the Bakong temple moat. Introduction Angkor was the location of the capital of the Khmer state for mostof the period from the eighth to sometime in the fifteenth and sixteenthcenturies AD. By the twelfth century Angkor had become a vastlow-density urban complex covering about 1000 sq. km (Fletcher et al.2003), stretching from the Tonle Sap lake in the south to the Kulenhills in the north. The urban complex incorporated numerous residentialloci that were integrated by an immense network of canals andembankments (Figure 1). Within Angkor, successive rulers built majortemples and palaces in several locations, shifting the focus of theurban complex until the late twelfth century AD when the centralenclosure of Angkor Thorn was constructed. In the seventh to ninthcenturies AD, there were concurrent residential loci around Ak Yum, andat Hariharalaya where Jayavarman II established his administration asthe newly anointed cakravartin (universal king) after AD 802 (Jacques1972). Hariharalaya (Roluos) was the site of several major constructionsincluding the massive temple-mountain of the Bakong, the first model ofthe Angkorian capital (Stern 1954) and the archetype of the pyramidaltemple. [FIGURE 1 OMITTED] One method of investigating this cultural sequence is throughpalynology pal��y��nol��o��gy?n.The scientific study of spores and pollen.[Greek palunein, to sprinkle + -logy. , which was successfully applied in the present researchproject. Vegetation is sensitive to the activities of people and thecomposition of the flora will often indicate the nature of land use atany given point in time. For example, the abandonment of land or theattenuation Loss of signal power in a transmission. AttenuationThe reduction in level of a transmitted quantity as a function of a parameter, usually distance. It is applied mainly to acoustic or electromagnetic waves and is expressed as the ratio of power densities. of land use will be clearly manifest in the flora, with apredictable successional shift from a cultivated flora to invasivecolonising plants, woody secondary forest and climax deciduous deciduous/de��cid��u��ous/ (de-sid��u-us) falling off or shed at maturity, as the teeth of the first dentition. de��cid��u��ousadj.1. forest.Such changes are identifiable in pollen sequences, and can be datedabsolutely. Palynological analysis at the site of Hariharalaya hadsignificance for several key periods in Angkorian history, including thedate for initial construction on the Bakong site in the eighth centuryAD, the impact of relocating the administrative centre to the vicinityof Phnom Bakeng in the late ninth century AD, and the conundrum of thedemise of Angkor some time in the fifteenth and sixteenth centuries AD.This paper presents the first continuous palynological reconstruction ofvegetation change at Angkor, encompassing the entire span of the ClassicAngkorian period. Site description (Figure 2) [FIGURE 2 OMITTED] Epigraphic ep��i��graph?n.1. An inscription, as on a statue or building.2. A motto or quotation, as at the beginning of a literary composition, setting forth a theme. evidence indicates that the Bakong temple wasinaugurated in AD 881 by King Indravarman I (AD 877-889) (Coedes 1951:31). It is a five-tiered pyramid, the first tier measuring 65 by 67m,built on an artificial mound, and topped by a central tower built in thetwelfth century AD to replace the original, which is thought to havebeen destroyed some time earlier (Boisselier 1952). The pyramid and itsnumerous associated buildings are surrounded by two walled enclosuresand two moats. The largest moat is 830 by 800m is size and 30-40m wide.The inner moat is 380 by 350m in size, 70-80m in width, and crossed tothe east and west by a causeway (Glaize 1993; Pottier unpublishedsurvey). The inner moat of the Bakong is deeply excavated into theregional alluvium al��lu��vi��um?n. pl. al��lu��vi��ums or al��lu��vi��aSediment deposited by flowing water, as in a riverbed, flood plain, or delta. Also called alluvion. , approximately 8m below the level of the templeplatform, and 5m below the land surface between the two moats.Consequently, despite the marked seasonal fluctuation in the groundwatertable the moat is likely to have carried water since its excavation,providing the conditions necessary for the preservation of organicmaterials. Groslier (1998: 40) hypothesised the existence of a hydraulicconnection between the moats of the Bakong and Preah Ko temples and theIndratataka reservoir to the north (Figure 2), but no evidence of such alink has yet been discovered. Prior to September 2004 when it wascleared, the moat was entirely overgrown overgrownsaid of a part that has not been kept trimmed.overgrown hoofovergrown hooves put unusual stresses on bones and tendons and allow for distortion of the wall and sole. with a thick mat of floatingvegetation that to our knowledge has not been disturbed throughout thetwentieth century--and in all probability much longer--protecting thesediment accumulating on the bed of the moat from disturbance by peopleor livestock. The vegetation surrounding the site today is a heavily disturbedmixed evergreen forest type that is species-poor relative to the primaryforests of the region (Ashwell & Fitzwilliams 1993; see also Rollet1972a, b, c; Boulbet 1979). Much of the surrounding area is undercultivation, including cultural features such as the seasonally dryouter moats of Preah K6 and Bakong, and the large trapeang (smallrectangular reservoirs) to the north-east of the Bakong, outside theexternal moat enclosure. Extensive fresh-water swamp forest occursapproximately 9km to the south at the margins of the Tonle Sap lake(McDonald et al. 1997). Materials and methods Cores of sediment were extracted from the inner moat of the Bakongtemple in July 2002, using a Kullenburg-type corer (Glew et al. 2001).The longest sequence recovered was 2.67m in length and 55mm in diameter(laboratory code BK/07/02/A), from a site approximately 60m south of theeastern causeway, in the approximate centre of the moat (Figure 3 no.4). [FIGURE 3 OMITTED] Core tubes were cut longitudinally in the laboratory. After visualdescription of the sediments, sub-samples were taken for pollen analysisat 10cm intervals between 0 and 190cm depth, and at 5cm depth between195 and 277cm depth. Laboratory protocols followed standard procedures(Berglund & Ralska-Jasiewiczowa 1986; Stockmarr 1971). Counting andidentification were undertaken at 400-1000 times magnification usingstandard transmitted light microscopy. Pollen taxa are expressed as apercentage of either a primary (trees, shrubs and other woody taxa) orsecondary (herbaceous her��ba��ceous?adj.1. Relating to or characteristic of an herb as distinguished from a woody plant.2. Green and leaflike in appearance or texture. plants and ferns) pollen group. Terminologyfollows Punt et al. (1994). Core BK/07/02/A is composed of two horizons: a black (5Y 2.5/2)peat (0.00-2.10m depth) with an acute lower boundary, over a very firmpinkish-grey (7.5YR 6/2) clayey-sand (2.10-2.67m depth). The peatdeposit, which is highly humified hu��mi��fied?adj.Converted into humus.Adj. 1. humified - converted to humus; "humified soil" and has a crumbly crum��bly?adj. crum��bli��er, crum��bli��estEasily crumbled; friable.crumbli��ness n.Adj. 1. rather than fibroustexture, we interpret as the autochthonous autochthonous/au��toch��tho��nous/ (aw-tok��thah-nus)1. originating in the same area in which it is found.2. denoting a tissue graft to a new site on the same individual. infill of the moat. The lackof mineral material in this horizon is expected, as there is no apparentfluvial flu��vi��al?adj.1. Of, relating to, or inhabiting a river or stream.2. Produced by the action of a river or stream.[Middle English, from Latin input to the moat, and sources of mineral sediment arerestricted to the banks of the moat and the fallout component. Theunderlying clayey sand is distinct from the regionalsubstrate--typically heavy, pale clay with abundant redox redox(rē`dŏks): see oxidation and reduction. features--andis interpreted as the initial infill of the moat immediately followingits excavation, comprised largely of mineral clasts reworked from thebanks of the newly excavated moat and the spoil from the excavation. Chronology (Figure 4) [FIGURE 4 OMITTED] A chronology for the core was provided by AMS-radiocarbon dating ofpollen concentrates. Eight samples were prepared following Brown et al.(1989). This procedure returned poor results in this case, with thepre-treated samples including sporopolleniferous algae algae(ăl`jē)[plural of Lat. alga=seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant kingdom, the thallophytes (plants that , fungal hyphae hy��pha?n. pl. hy��phaeAny of the threadlike filaments forming the mycelium of a fungus.[New Latin, from Greek huph ,cellulose and charcoal fragments. The ages presented here are,therefore, based on a mixed assemblage of organic materials <120[micro]m in size, rather than a pure pollen fraction. Radiocarbonresults are shown in Table 1, and plotted in Figure 4. OZG481 andOZH OZH One or Zero Helpdesk 177, based on samples taken immediately above the acute boundary thatmarks the initiation of organic sedimentation with the moat, return agesof 1290 [+ or -] 40 and 1250 [+ or -] 50 years BP, which arestatistically indistinguishable at the 95 per cent confidence level (T =0.39; Ward & Wilson 1978), combining to provide a weighted averageage of 1274 [+ or -] 31 years BP (Stuiver & Reimer 1993, version5.0). This pooled age calibrates to AD 680770 AD (1[sigma]). OZH174returned a modern age, which is consistent with the slope of theage/depth curve (Figure 4), and is indicative of the thick fibrous matof modern and recent vegetation at the top of the profile. OZG480(10-11cm depth) is, therefore, erroneously old with respect to itsneighbouring dates, possibly reflecting the in-wash of 'old'carbon from the banks of the moat as a result of some recentdisturbance. The banks of the moat and the causeways that cross it areknown to be unstable. Reports from the Angkor Conservation Office, forinstance, indicate that the northern side of the eastern causewaycollapsed in 1949, 1951 and 1952, and the distribution of fallenlaterite lateriteSoil layer rich in iron oxide and sometimes aluminum, derived from a wide variety of rocks by leaching. It forms in tropical and subtropical regions where the climate is humid. blocks and sandstone pieces of the ornamental and monumentalnaga balustrade on the south side of the eastern causeway revealed mucholder episodes of bank collapse. OZH176 (187cm depth) appears erroneously young with respect to itsneighbouring dates. The reason for this inversion, and the significanceof its coincidence with a major palynological boundary (between 180 and190cm depth; see below), is unknown. Similar instances of age inversionhave been reported from other Southeast Asian sites with floatingvegetation mats (see Maloney 1984: 44), where younger material'rafts' under the mat and is subsequently interred. Moreover,in instances where the sediment below the mat is highly unconsolidated,sloughing of younger material from the base of the floating mat may leadto substantial age inversions. Clearly, the sedimentation history ofthis site is more complex and subtle than the stratigraphy would imply.In any event, we consider that OZH176 and OZG480 represent inversions inthe core stratigraphy, and are omitted here for the purposes ofcalculating the chronological model (Figure 4). Palynology and sedimentary charcoal (Figure 5) [FIGURE 5 OMITTED] 114 pollen and spore types were identified from 24 samples between0 and 210cm depth. No specimens were observed at or below 215cm depth.The number of specimens counted per sample ranged between 116 and 1221,with a mean of 554 specimens. Stratigraphically constrainedclassification (Grimm 1987) of the pollen and spore assemblagesindicates three sample groups representing successive vegetation phases. At vegetation Phase 1 (see Figure 5) (210-190cm depth) the arboreal arborealpertaining to trees, treelike, tree-dwelling. component is dominated by Celtis tetrandra-type and Macaranga, withpalms (Arecaceae Sabal-sim. and Borassus flabellifer),Combretaceae/Melastomataceae, Pinus merkusii, Quercus, andUrticaceae/Moraceae commonly recorded. Poaceae and Cyperaceae dominatethe nonarboreal pollen sum. Aquatic plants and ferns are rare andrecorded sporadically. Charcoal particle concentrations are relativelyhigh, with an average value of 1.8 x [10.sup.6] particles/[cm.sup.3]. At Vegetation Phase 2 (180-80cm depth) there is a fundamentalchange in the vegetation. Ilex cymosa (swamp holy) increases markedly tobecome the dominant tree pollen type, while those taxa dominant in theprevious phase (Celtis tetrandra-type, Macaranga and Pinus merkusii, inparticular) are severely reduced. The relative abundance of Uncaria-typeincreases steadily through the phase to become the sub-dominant arborealpollen type. Eugenia-type is more abundant than in the previous phase,but its representation remains low and variable. Palms are less common,particularly Borassus flabellifer, which becomes rare. Poaceae andCyperaceae values also fall markedly in this zone, while fern spores(psilate- and verrucate-monolete forms in particular, but also theclimbing fern Steonchlaena palustris) are strongly represented. Charcoalparticles are less abundant than in the preceding phase, with an averageconcentration of 0.9 x [10.sup.6] particles/[cm.sup.3]. Algae were rareor absent. Vegetation Phase 3 (70-0cm depth) is characterised by a discretefall in Ilex cymosa pollen values from 70 to 40cm depth and, whilevalues increase again above 30cm depth, I. cymosa pollen values remainlow relative to the preceding vegetation phase. This is coincident withhigher values for Uncaria-type, Eugenia-type, and a slight increase inPinus merkusii. Trema, Celtis and Macaranga all increase to reach maximaat 40-50cm depth, while Borassus flabellifer reappears in the pollenrecord at 40cm depth (absent from the record since 100cm depth).Calophyllum, which to that time had only been a minor component of theflora, increases markedly at 20cm depth. Fern spores are again verycommon in these sediments, while Poaceae and Cyperaceae pollen grainsare relatively rare, excepting a discrete peak in Cyperaceae values at40cm depth, and a slight increase in Poaceae above 20cm depth.Nymphoides remains the most common of the aquatic plants. Charcoalparticle values are relatively low (an average of 0.4 x [10.sup.6]particles/[cm.sup.3]), but increase above 30cm. Discussion The historical date for the inauguration of the Bakong temple byIndravarman is AD 881, yet the inner moat of the temple, which definesits inner enclosure, was constructed some time between the late seventhand late eighth century AD, more than a century before the temple wascomplete, and most likely decades before Jayavarman II reputedlyinitiated the cult of devaraja and assumed the title cakravartin in AD802. Prima facie, this date corroborates Pottier's (1996) analysesthat scrutinised the chronology of Indravarman's capital, and thecommonly accepted interpretation of epigraphic texts. In particular,these new radiocarbon dates confirm an earlier origin and a more complexsequence for the Bakong, opening the way for a redefinition of thecurrent idealised Angkorian urban model (Stern 1954), and demonstratingthe need for a detailed reappraisal of the earliest urban development inAngkor combining new concepts of urbanism with rigorous empiricalresearch. The palynological data presented here indicate an intensively usedagricultural landscape around the site for more than a century, from themid-late eighth to the late ninth century AD (Phase 1). The strongrepresentation of grass pollen and absence of deciduous canopy trees isindicative of sparse forest cover, and the presence of Pinus merkusiipollen implies an open landscape in which a regional influence issignificant. The high charcoal particle values imply frequent burning,although the relatively strong presence of Macaranga, a well-knownindicator of disturbance and secondary forest development, suggests thatreturn intervals were not sufficient to suppress regrowth Re`growth´n. 1. The act of regrowing; a second or new growth.The regrowthof limbs which had been cut off.- A. B. Buckley. . A number ofuseful plants are apparent, particularly Celtis tetrandra-type,typically a timber tree (Po 2003) but also with edible fruit, and thepalmyra palm, Borassus flabellifer. Borassus is particularly important for inferring agricultural landuse. Stargardt (1983: 68, 128) considers it to be 'second ... onlyto rice' in terms of its economic importance, and Fox (1977: 200)describes Borassus as chief among those plants 'inextricablyinvolved in human history'. The uses of Borassus are legion(lumber, thatch, rope, edible fruit, fodder, sweet juice from theinflorescence inflorescenceCluster of flowers on one or a series of branches, which together make a large showy blossom. Categories depend on the arrangement of flowers on an elongated main axis (peduncle) or on sub-branches from the main axis, and on the timing and position of flowering. , which can be taken directly, reduced into a syrup or hardsugar, or distilled to make alcohol), and in Cambodia, as in other partsof Southeast Asia (Fox 1977), individual plants are owned by familygroups or rented on a seasonal basis (Ebihara 1968: 292). The productionand consumption of Borassus products are universally associated with thepoor, and primarily service local markets (Fox 1977: 205-207). ZhouDaguan noted in the late thirteenth century, for example, that winedistilled from sugar--again, presumably pre��sum��a��ble?adj.That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. from Borassus--was 'last inimportance' of the fermented drinks (2001: 75). Borassus is thought to have originated in India and Sri Lanka,though there is no compelling evidence to support this. Along with theAfrican genus Hyphaene, Borassus has a distinctive pollen type(monosulcate, with sparse supratectal gemmate sculpture; Ferguson &Harley 1992) and the number of palynological studies in the region isnow sufficient (Penny & Kealhofer 2005; White et al. 2004; Bishop etal. 2003; Maxwell 2001; Boyd & McGrath 2001; Penny 2001; Kealhofer& Penny 1998; Maloney 1991, 1999) to permit some preliminarycomments on its palaeo-biogeography. The first occurrence of Borassusflabellifer pollen in the fossil record of mainland Southeast Asiaoccurs on the Malay peninsula, in sediments recovered from a sixthcentury AD canal at Satingpra (Stargardt 1983). At Angkor Borei,southern Cambodia, Borassus pollen is recorded at a depth of 117cm in asediment core extracted from a small reservoir, dated to the mid-seventhcentury AD (Bishop et al. 2003). An inscription (K.9) records thatorchards of the plant (tpal tern tunnot;, Coedes 1953: 35) werepresented as gifts in the seventh century AD in Vietnam. These earlyoccurrences of Borassus at entrepots located on the east-west traderoute between China, India and Europe imply that Borassus hadestablished a beachhead in mainland Southeast Asia some time between thesixth and seventh century AD. The pollen data presented here indicatethat Borassus was growing in the Angkor region by the eighth century ADat least, and probably earlier. The staccato-like occurrence of Borassus pollen in the fossilrecord renders its palaeo-biogeography 'disconcertinglycircumstantial', according to Maloney (1994: 147). Its rarityoutside cultural loci is due to its entomophily (Ramanujam & Kalpana1995) and low pollen productivity, which is four times lower per flowerthan Cocos nucifera, another economically useful palm (Subba Reddi &Reddi 1986), seven times lower than Shorea (Bera 1990), a common foresttree in the area, and eleven and ninety times lower than theover-represented genera Pinus and Quercus, respectively (Erdtman 1969).This means that even a sparse occurrence in pollen assemblages isstrongly indicative of its local presence in the landscape. Furthermore,Borassus is both slow growing and propagated from seed (Thorel 2001:128), and is relatively shade-intolerant (Chandrashekara & Sankar1998: 173), making it particularly susceptible to competition from moreaggressive colonial plants. This suggests that Borassus is not viableunless tended and is gradually selected against as secondary forestsregenerate, emphasising the 'close and complementary'(Stargardt 1983: 129), almost symbiotic relationship between agricultureand Borassus arboriculture arboricultureCultivation of trees, shrubs, and woody plants for shading and decorating. Arboriculture includes all aspects of growing, maintaining, and identifying plants, arranging plantings for their ornamental values, and removing trees. . In the Bakong pollen record Borassus pollen reaches a maximumrepresentation in the early-mid ninth century AD, and declinesthereafter. There are only two occurrences of the pollen between theearly twelfth to early eighteenth century AD. The initial decline ofBorassus is coincident with a dramatic and widespread change in theflora. The marked decrease in the abundance of grass pollen and fallingcharcoal particle concentrations suggest a decrease in the frequency ofburning, although there is no apparent expansion of deciduous forestsdue, presumably, to the under-representation of the most commondeciduous species (Bera 1990; Ashton 1982; Chan & Appanah 1980) andthe over-representation of plants growing on or immediately adjacent tothe core site. These changes are coincident with the colonisation of the moat byhydrophytic plants. The sudden dominance of ferns suggests thatvegetation had invaded the moat during the early-mid tenth century(180cm depth). Once an adequate substrate had formed from these initialcolonisers, hydrophilic hydrophilic/hy��dro��phil��ic/ (-fil��ik) readily absorbing moisture; hygroscopic; having strongly polar groups that readily interact with water. hy��dro��phil��icadj. woody plants became established in the moat. Ofthese, Ilex cymosa was the most common. Ilex is a common component ofpeat swamp forest Peat swamp forests are tropical moist forests where waterlogged soils prevent dead leaves and wood from fully decomposing, which over time creates thick layer of acidic peat. Large areas of these forests are being logged at high rates. in Southeast Asia and, prior to c. 5600 years BP,occurred in floodplain floodplain,level land along the course of a river formed by the deposition of sediment during periodic floods. Floodplains contain such features as levees, backswamps, delta plains, and oxbow lakes. vegetation around the Tonle Sap lake under arelatively stable inundation INUNDATION. The overflow of waters by coming out of their bed. 2. Inundations may arise from three causes; from public necessity, as in defence of a place it may be necessary to dam the current of a stream, which will cause an inundation to the upper lands; regime (Penny 2006), but became rare duringthe later Holocene as seasonality increased. Ilex is no longer presentin the modern 'flooded forest' of the Tonle Sap (McDonald etal. 1997). The presence of I. cymosa and other typical swamp-foresttrees (Calophyllum, Eugenia-type, Barringtonia) in the moat of theBakong reflects the development of localised freshwater peat-swampforest that owes its existence to the relatively shallow water table anda sheltered micro-environment afforded by the deeply incised moat. Thegradual increase in the representation of the epiphytic ep��i��phyte?n.A plant, such as a tropical orchid or a staghorn fern, that grows on another plant upon which it depends for mechanical support but not for nutrients. Also called aerophyte, air plant. fernStenochlaena palustris and the liana liana(lēä`nə)or liane(lēän`), name for any climbing plant that roots in the ground. Uncaria-type probably reflectsdevelopment of larger woody shrubs and small trees within the moat. For more than 150 years from the mid-late eighth century the moathad remained relatively clear of aquatic vegetation, which we presumeindicates deliberate clearing of colonising swamp plants, as it wouldhave taken only a few years in such a sheltered environment, perhapsless, for vegetation to close over the moat. It appears that suchmaintenance ceased in the early-mid tenth century. The colonisation ofthe moat is coincident with a decrease in the intensity of land usearound the temple. The decrease in burning, the dramatic declines ingrass (which, no doubt, includes rice), and the gradual exclusion ofBorassus flabellifer from the flora, are all indicative of a markeddecrease in the use of land for agriculture. These substantial changesin land use are coincident with the movement of Yasovarman I'sadministration from Hariharalaya to Yasodharapura at the centre ofpresent day Angkor toward the end of the ninth century AD. Oneinterpretation of these data is that with the relocation to thenorth-west, Hariharalaya ceased to be a central focus for settlement inthe region and became peripheral to the urban complex. An alternative interpretation is that layout of the temple wasreformulated in the ninth century to include a second, larger moat. Thismay have precluded agricultural land use immediately surrounding thetemple (between the first and second enclosures), but would havepermitted agricultural life to continue unabated in the immediatehinterland, beyond the sacred enclosures. In that respect, it is alsointeresting to note that no specific changes in the flora in orsurrounding the inner moat are apparent in the twelfth century, during aperiod of obvious architectural rejuvenation, with the building ofseveral structures including the central shrine topping the pyramid.This architectural resurgence, it appears, did not extend to theclearance of the moat or the removal of vegetation from the surroundingland. Further changes in the flora of the moat are apparent from theearly-mid fifteenth to early sixteenth century (70-80cm depth). Themarked decline in Ilex cymosa, and extremely subtle changes in therepresentation of other swamp plants (notably Eugenia-type and the fernfamily Polypodiaceae) indicate successional changes in the swamp-forest.The reasons for this are unknown, but may relate to excessive shading ofthe dominant woody shrubs by climbing plants such as Uncaria andStenochlaena palustris, both of which have their strongestrepresentations at this time. Further declines in charcoal particleconcentrations are apparent between the mid fifteenth to mid eighteenthcenturies, reaching a minimum in the mid-late seventeenth century.Regionally, land use for agriculture may have been at its mostattenuated at that time. There is no evidence of the supposed fifteenth century AD sack ofAngkor. The dryland pollen assemblages appear stable, while thosechanges that are apparent are subtle, extremely localised and driven bysuccessional processes rather than by changes in land use. However, itmay be that the final sack of Angkor had little or no physical impact atHariharalaya which may, at that time, have been already thinly occupiedand, perhaps, of little strategic importance. Unequivocal evidence ofdisturbance in the dryland vegetation at Haraiharalaya occurs from thelate seventeenth to mid eighteenth centuries (50-40cm), with increasesin secondary forest (Trema, Macaranga), grasses, increases in charcoalparticles and reappearance of Barassus flabellifer. Taken together,these data imply a limited re-activation of the landscape foragriculture, but the intensity of land use appears to be markedly lowerthan that apparent during Hariharalaya's zenith in the eighth andninth centuries AD. Conclusion These data constitute the first palynological record of land-coverand land-use change at Angkor from the pre-Angkorian period to thepresent day. They indicate that the inner moat of the Bakong temple,which represents the main temple enclosure, was dug in the eighthcentury AD, prior to the historical date for the construction of thetemple itself. Agricultural land-use around the Bakong temple wasintense until the late ninth century AD, after which time the intensityof land-use declined. This is consistent with the movement of thecapital from Hariharalaya to Yasodharapura (centred on Phnom Bakeng),and implies that from that time on Hariharalaya was on the periphery ofAngkor. There is no evidence indicating widespread land-abandonment inthe fifteenth century associated with the supposed Thai invasion. Ratherthere is a gradual attenuation of land use around the Bakong templeafter the ninth century culminating in what appears to be nearabandonment in the mid seventeenth century AD. Agricultural land use didnot clearly reappear at Roluos until the eighteenth century. Acknowledgements This research is part of the Greater Angkor Project, acollaborative project between the University of Sydney The University of Sydney, established in Sydney in 1850, is the oldest university in Australia. It is a member of Australia's "Group of Eight" Australian universities that are highly ranked in terms of their research performance. , Ecole Francaised'Extreme-Orient and APSARA APSARA Autorit�� pour la Protection du Site et l'Am��nagement de la R��gion d'Angkor (Cambodia), the Cambodian government bodyresponsible for the management of Angkor and Siem Reap. Funding isprovided by the Australian Research Council (DP0211012 and DP0211600),the University of Sydney U2000 Postdoctoral Research Fellowship scheme,and the Institute of Nuclear Science and Engineering (AINSE AINSE Australian Institute of Nuclear Science and Engineering ) (Grant03/091P). Thanks to Mitch Hendrickson, Damian Evans and Eileen Lustigfor their assistance in the preparation of the manuscript, and to SamPlayer, Maital Dar and Tous Somaneath for assistance in the field. Received: 1 November 2004; Revised: 23 August 2005; Accepted: 21October 2005 References ASHTON, P.S. 1982. Dipterocarpaceae. 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Agriculture and Ethnobotany ethnobotany/eth��no��bot��a��ny/ (-bot��ah-ne) the systematic study of the interactions between a culture and the plants in its environment, particularly the knowledge about and use of such plants. of the Mekong Basin.The Mekong Exploration Commission Report (1866-1868) Volume 4, transW.E.J. Tips. Bangkok: White Lotus Press. WARD, G.K. & S.R. WILSON. 1978. Procedures for comparing andcombining radiocarbon age determinations: a critique. Archaeometry 20(1): 19-31. WHITE, J.C., D. PENNY, B. MALONEY, L. KEALHOFER. 2004. Vegetationchanges from the Terminal Pleistocene through the Holocene from threeareas of archaeological significance in Thailand. QuaternaryInternational 113:111-32. ZHOU, D. (CHOU, T.-K.) 2001. The customs of Cambodia. Bangkok: TheSiam Society. Dan Penny (1), Christophe Pottier (2), Roland Fletcher (3), MikeBarbetti (4), David Fink (5) & Quan Hua (5) (1) School of Geosciences, University of Sydney, Sydney, NSW NSWNew South WalesNoun 1. NSW - the agency that provides units to conduct unconventional and counter-guerilla warfareNaval Special Warfare 2006,Australia (Email: d.penny@geosci.usyd.edu.au) (2) Ecole Francaise d'Extreme Orient, P.O. Box 93300, SiemReap, Cambodia (3) Department of Archaeology, University of Sydney, Sydney, NSW2006, Australia (4) NWG NWG Network Working GroupNWG Northumbrian Water Group (UK)NWG Neighbourhood Watch Group (Singapore)NWG Non-Working Girl (non-prostitute)NWG NewAge Tech LTD. Macintosh Centre, University of Sydney, Sydney, NSW2006,Australia (5) Australian Nuclear Science and Technology Organisation, PMB PMB Private Message BoardPMB Print Measurement BureauPMB Performance Measurement BaselinePMB Private Mail Box (non-USPS)PMB Plant and Microbial BiologyPMB Private MailboxPMB Physics in Medicine and Biology No.1, Menai Sydney, NSW 2234, AustraliaTable 1. Results of AMS radiocarbon dating of pollen samples fromcore BK/07/02/A, Bakong temple moat, Angkor, Cambodia. These ageswere measured by AMS radiocarbon using the ANTARES facility atANSTO (Hua et al. 2001; Fink et al. 2004). Radiocarbon dates arecalibrated (Stuiver & Reimer 1993 version 5.0) using the IntCal04curve (Reimer et al. 2004). Ages are calibrated to years AD,representing 68.2 per cent and 95.4 per cent confidence levelsrespectively, and years BP (95.4 per cent confidence only). Figuresin square brackets indicate the proportion of the probabilityrange represented by each intersection of the probability curve(thus, 1 is equal to 68.2 or 95.4 per cent). Ranges marked withan asterisk (*) are suspect due to impingement on the end of thecalibration data set. Measured [[delta].sup.13] C values relatesolely to the graphite derived from the material used forradiocarbon measurement. [delta] Percent modern Depth ([.sup.13]C) (pMC) [+ or -]Lab. Code (cm) per mil 1 [sigma] errorOZG480 10-11 -28.3 94.89 [+ or -] 0.45OZH174 20-21 -27.7 109.85 [+ or -] 0.50OZG482 40-41 -28.7 97.63 [+ or -] 0.45OZH175 85-86 -29.2 94.10 [+ or -] 0.42OZG483 140-141 -26.8 90.28 [+ or -] 0.43OZH176 187-188 -24.2 94.27 [+ or -] 0.45OZG481 207-208 -22.9 85.21 [+ or -] 0.40OZH177 208-210 -24.4 85.54 [+ or -] 0.53 Radiocarbon age ([sup.14]C years Calibrated ageLab. Code BP [+ or -] 1 range BP (2[sigma] [sigma]) 95.4% probability)OZG480 420 [+ or -] 40 321-378 [0.175867] 389-390 [0.001249] 427-530 [0.822884]OZH174 modern --OZG482 195 [+ or -] 40 * -2-34 [0.176637] 71-116 [0.059981] 134-227 [0.513038] 252-307 [0.250344]OZH175 490 [+ or -] 35 496-553 [0.982617] 611-620 [0.017383]OZG483 820 [+ or -] 40 673-795 [0.986605] 878-892 [0.013395]OZH176 475 [+ or -] 40 466-554 [0.986221] 610-621 [0.013779]OZG481 1290 [+ or -] 40 1093-1106 [0.013874] 1137-1162 [0.035908] 1167-1297 [0.950218]OZH177 1250 [+ or -] 50 1066-1282 [1.00] 789-811 [0.140779] 846-856 [0.05068] Calibrated age range Calibrated age range AD (1 [sigma] 68.2% AD (2 [sigma] 95.4%Lab. Code probability) probability)OZG480 1433-1491 [0.926329] 1420-1523 [0.822884] 1603-1611 [0.073671] 1560-1561 [0.001249] 1572-1629 [0.175867]OZH174 -- --OZG482 1659-1682 [0.222391] 1643-1698 [0.250344] 1736-1804 [0.618262] 1723-1816 [0.513038] 1936-1951 * [0.159347] 1834-1879 [0.059981] 1916-1952 * [0.176637]OZH175 1416-1441 [1.00] 1330-1339 [0.017383] 1397-1454 [0.982617]OZG483 1187-1199 [0.146346] 1058-1072 [0.013395] 1206-1261 [0.853654] 1155-1277 [0.986605]OZH176 1417-1447 [1.00] 1329-1340 [0.013779] 1396-1484 [0.986221]OZG481 670-721 [0.63193] 653-783 [0.950218] 741-770 [0.36807] 788-813 [0.035908] 844-857 [0.013874]OZH177 682-782 [0.80854] 668-884 [1.00]