Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46 – 56 www.elsevier.com/locate/palaeo
A late glacial to present diatom record from Lake Euramoo, wet tropics of Queensland, Australia J. Tibby a,⁎, S.G. Haberle b b
a Geographical and Environmental Studies, University of Adelaide, Adelaide, SA 5005, Australia Department of Archaeology and Natural History, Research School of Pacific and Asian Studies, Australian National University, Canberra, ACT 0200, Australia
Accepted 27 February 2007
Abstract A new diatom record from Lake Euramoo on the Atherton Tableland, north Queensland, Australia is used to assess regional climate change and variability and their links to forcing at a local to global scale. The major factor driving diatom composition in the approximately fifteen thousand-year record appears to be regional moisture availability. Patterns of diatom preservation and other indicators, particularly sediment organic content, suggest that permanent deep water formed at the site from ca. 15,000 cal. yr BP. However, between 13,800 and 11,500 cal. yr BP, there was a notable phase of lower lake levels and effective precipitation. The timing and duration of this phase does not correspond to large-scale climate phenomena such as the Antarctic Cold Reversal or the Younger Dryas and supports emerging evidence for a variable climate regime in the south-west Pacific during the late glacial transition. The Early to Mid Holocene record is one of remarkable stability with 5000 years of sustained dominance by the planktonic diatom Aulacoseira ambigua. Conversely, the Mid to Late Holocene record is marked by distinct diatom variability superimposed on a series of sustained shifts in composition. Accentuated Late Holocene climate variability may aid in explaining intensified land use in indigenous populations and also suggests that Europeans may have arrived in the landscape at the time it was most vulnerable to perturbation. © 2007 Elsevier B.V. All rights reserved. Keywords: Pleistocene; Holocene; Tropical; Palaeolimnology; Climate; Lake level
1. Introduction The Late Quaternary history of the humid fringe of Australia in general, and of north-east Queensland in particular, is dominated by records derived from pollen analysis of lakes and swamps (Kershaw and Nanson, 1993). These records have provided an invaluable insight into regional and global scale climate change ⁎ Corresponding author. Tel.: +61 8 8303 5146; fax: +61 8 8303 4347. E-mail address:
[email protected] (J. Tibby). 0031-0182/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2007.02.017
and variability (Kershaw, 1974, Turney et al., 2004), the nature and timing of human occupation (Kershaw, 1986) and the development and dynamics of rainforest vegetation (Walker and Chen, 1987; Haberle, 2005). While such records are of immense value, the nature of (dryland) vegetation response to external forcing means that it may take decades to centuries for pollen records to reach equilibrium with climate (Walker and Chen, 1987). Such outcomes are problematic when issues such as centennial scale climate variability or interhemispheric climate linkages are assessed. A variety of
J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56
other proxies exist which are capable of examining such issues (e.g. tree rings or coral banding). These are characterised by substantial environmental sensitivity and both high temporal resolution and precision (e.g. Hendy et al., 2002). However, such records are often limited in temporal and/or spatial extent, particularly in the Australasian region (see Fig. 1a in Mann et al., 1998). In this context, we present a new diatom record covering approximately the last 15,000 years from Lake Euramoo in north-east Queensland. Due to their short life cycles and sensitivity to a variety of climate-related water quality and aquatic habitat characteristics, diatoms are increasingly being utilised as indicators of Quaternary climate change and variability (Smol and Cumming, 2000). In Australia, despite a long recognition of the sensitivity of diatoms to their environment (Reid et al., 1995), which has included the development of a number of water quality transfer functions (e.g. Gell, 1997; Tibby et al., 2003; Tibby, 2004) and some of the earliest efforts at quantitative environmental reconstructions (Tudor, 1973) there has been a general paucity of Late Quaternary diatom records. Indeed, there are very few records with any Pleistocene antiquity (Bradbury, 1986, Tibby et al., 2006; Turney et al., 2006), with only Tibby et al. (2006) providing data from the last glacial maximum through the Holocene. This and other records from western Victorian crater lakes (Tudor, 1973; Gell et al., 1994; Tibby et al., 2006) appear to be the only Australian diatom records that cover the entire Holocene.
47
2. Study site Lake Euramoo (718 m above sea level, 17°10′S, 146°38′E, Fig. 1) is one of a small number lakes formed in Late Quaternary volcanic craters on the Atherton Tableland, an uplifted Tertiary region which has peaks rising to over 1500 m. The site lies near the western margin of wet tropical rainforest, although vegetation within the crater has been substantially modified by human agency (Kershaw, 1970; Haberle et al., 2006). Rainfall at the site is estimated to be ∼ 1500 mm per annum, with the majority (60%) falling predominantly between January and March. The lake is warm monomictic, with a water depth averaging around 20 m in the southern basin and 16 m in the northern basin, though there are seasonal fluctuations in water depth of between 2 and 3 m (Timms, 1976). Lake Euramoo is very fresh (31 parts per million salt) and slightly acidic (with a mean pH measured in 1973–1974 of 6.31, Russell, 1987). Extensive (N30 m wide) marginal fixed and floating root mat vegetation is found around the Lake, particularly in the southern basin (Kershaw, 1979). 3. Methods Coring, sampling and dating methods are detailed in Haberle (2005) and Haberle et al. (2006) and are briefly summarised here. Cores were raised from a water depth of 16 m in the centre of the northern basin of Lake Euramoo in 1999. A clear plastic piston corer was used
Fig. 1. Location of Lake Euramoo, distribution of rainforest in the north-east Queensland region and generalised topography (from Haberle, 2005).
48
J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56
to obtain the top 2 m of sediments in an undisturbed manner. These sediments were extruded vertically and sectioned in 1 cm increments in the field. The remaining sediments were sampled in 1 m sections using a Livingstone corer and were extruded horizontally into trays and wrapped. Sample ages were determined using the age-depth model in Haberle (2005) and Haberle et al. (2006) and are expressed in calibrated years before 1950 (cal. yr BP) and rounded to the nearest 50 years. The age-depth model (reproduced here in Fig. 2) is based on 22 calibrated 14C determinations (Table 1) and a 210Pb-based chronology constrained by historical data. The sampling resolution for diatom analysis varied. A minimum resolution of four centimetres was implemented in the top metre of the core to document changes resulting
from, and leading up to, European contact. From the late glacial to the Early Holocene (8600 cal. yr BP, 615 cm sediment depth), samples were analysed at 6–9 cm intervals (providing a temporal resolution of between ca. 420 and 630 years). The resolution of the data varied somewhat through the remainder of the record but averages approximately 14 cm between samples (average between sample resolution, ca. 240 years, maximum ca. 365 years). Diatom sample depths are routinely expressed as centimetres below the sediment surface, with depth below water surface occasionally provided to facilitate comparison with Haberle (2005). Diatoms were prepared using a modified version of the technique outlined in Renberg (1990). Diatoms were identified at 1000× magnification, using either a Zeiss
Fig. 2. Age–depth relationship of Lake Euramoo sediments (see text for details).
J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56 Table 1 C radiocarbon AMS sample results from the Australian Nuclear Science and Technology Organisation radiocarbon laboratory
14
ANSTO Sample (13C) code type and ID per (cm below mil water level) OZE682 EU 1695– 1696 OZE683 EU 1790– 1790
−27.9
Conventional age 14
C yr BP
50
−30.1 1320
40
OZE684 EU 1857– 1858
−31.8 2410
40
OZE685 EU 1925– 1926 OZE686 EU 2040– 2041
−33.5 3510
40
−31.7 4090
40
OZH310 EU 2201– 2202
−33.9 6210
−31.1 5690
OZH311 ⁎EU 2219– −31.7 7860 2220
OZH312 EU 2246– 2247
−21.3 9400
C
1σ error
570
OZE687 EU 2157– 2158
14
50
50
60
80
OZH313 EU 2255– 2256
−25.5 9530
60
OZH688 EU 2263– 2264
−28.5 9640
60
Calibrated age, cal yr BP (CALIB v4.4, 2σ error) 490–570 (80%) 590–630 (20%) 1080–1110 (5%) 1120–1160 (9%) 1170–1290 (86%) 2320–2490 (85%) 2630–2710 (15%) 3630–3840 (100%) 4420–4630 (92%) 4760–4800 (8%) 6900–7210 (99%) 7220–7230 (1%) 6640–6580 (9%) 6570–6400 (86%) 6370–6350 (4%) 6330–6320 (1%) 8980–8910 (11%) 8900–8880 (4%) 8870–8830 (7%) 8810–8540 (78%) 11,070–10,940 (11%) 10,860–10,830 (2%) 10,810–10,800 (1%) 10,790–10,400 (86%) 11,110–10,660 (99%) 10,620–10,610 (1%) 11,190–11,050 (40%) 11,040–10,780 (60%)
49
Table 1 (continued ) ANSTO Sample (13C) code type and ID per (cm below mil water level) OZH314 ⁎EU 2270– −23.2 2271
Conventional age 14
C yr BP
14
1σ error
9800
90
OZH315 ⁎EU 2275– −29.1 10,130 2276
60
OZH316 EU 2282– 2283
−27.2 10,640
60
OZE838 EU 2292– 2293
−24.0 11,100
60
OZH317 ⁎EU 2303– −26.6 2304
C
9110
60
OZH318 EU 2315– 2316
24.6 11,230
60
OZE689 EU 2341– 2342 OZH319 EU 2361– 2362 OZH320 EU 2389– 2390 OZH321 EU 2413– 2414 OZE690 EU 2430– 2435
−26.4 12,600
70
−25.0 15,820
120
−24.8 11,310
70
−18.6 18,960
160
−24.1 19,130
90
Calibrated age, cal yr BP (CALIB v4.4, 2σ error) 11,550–11,500 (4%) 11,450–11,390 (3%) 11,360–11,060 (81%) 10,950–10,840 (9%) 10,830–10,760 (3%) 12,280–12,220 (3%) 12,130–11,540 (83%) 11,520–11,400 (10%) 11,390–11,340 (4%) 12,950–12,600 (76%) 12,500–12,340 (24%) 12,670–12,720 (3%) 12,870–13,190 (96%) 13,310–13,340 (1%) 10,470–10,460 (2%) 10,430–10,180 (98%) 13,760–13,700 (3%) 13,460–13,000 (97%) 14,240–15,540 (100%) 19,550–18,270 (100%) 13,310–13,070 (100%) 22,940–22,170 (100%) 21,930–23,430 (100%)
All samples are derived from bulk organic detritus with the exception of 4 pollen preparation samples (marked by an asterisk). Calibration results from CALIB v4.4 (Stuiver and Reimer, 1993). The midpoint of calendar year range marked in bold are used in age-depth model calculations (3 samples excluded from the age-depth model are not in bold).
50 J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56
Fig. 3. Diatom record from Lake Euramoo. Only taxa n N 1 and with maximum relative abundance N3% are displayed. Sponges spicules are expressed as a proportion of the diatom sum. The grey shading highlights sediments consisting of coarse debris from a floating root mat or fallen tree (see Haberle, 2005 for details).
J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56
Fig. 4. Summary multiproxy data from Lake Euramoo. Illustrated are sediment properties, summary dryland pollen, key aquatic pollen types and charcoal accumulation data from Haberle (2005) and the most abundant diatom taxa. The grey shading highlights coarse debris from a floating root mat or fallen tree. Also highlighted are the Antarctic Cold Reversal (ACR), following Jouzel et al. (1995) and Blunier and Brook (2001) and the Younger Dryas Chronozone (YDC), defined as Greenland Stadial 1 in Björck et al. (1998).
51
52
J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56
Axioscope with differential interference contrast optics or with an Olympus BH2 microscope with bright field illumination. Diatoms were identified with reference to a variety of sources (in particular, Krammer and LangeBertalot, 1986, 1988, 1991a,b; Vyverman, 1991). A minimum of 300 valves per sample were counted with the exception of the following depths where low valve densities prevented full counts: 192 cm (n = 89), 209 cm (n = 205), 233 cm (n = 292), 519 cm (n = 289) and 711 cm (n = 240.5). Diatom relative abundance data are presented using C2 (Juggins, 2004). The diatom diagram was zoned with the aid of stratigraphically constrained cluster analysis implemented in CONISS (Grimm, 1987) on all taxa exceeding 1% in any sample, using Euclidean distance as a measure of similarity. A grouping of unidentified taxa was excluded from this analysis. Correspondence analysis was undertaken on these data following square root transformation to reduce the influence of highly abundant taxa in Canoco for Windows 4.02 (ter Braak and Šmilauer, 1999). 4. Results 4.1. Zone 4 (647–711 cm sediment depth, 2247–2311 cm bws, 10,400–14,900 cal. yr BP)
lower than in subzone 3b. Eunotia pectinalis enters the record for the first time in substantial numbers in this zone and is sub-dominant in the majority of samples. The other notable feature of this zone is the consistent representation of Sellaphora americana, a diatom which appears in few other samples in the record. 4.4. Zone 2 (64–209 cm sediment depth, 1809–1664 cm bws, 1560–300 cal. yr BP) Zone 2 is characterised by the dominance of E. pectinalis in most samples. Aulacoseira sp. 1, though variable, exhibits a general increase from the middle part of the zone. Sponge spicules are at their most abundant, particularly in the early part of this zone. 4.5. Zone 1 (0–64 cm sediment depth, 1664–1600 cm bws, 300 cal. yr BP–1999 AD) Diatom compositional changes in zone 1 have already been analysed by Haberle et al. (2006). This zone sees continued decreases in E. pectinalis combined with complementary increases in Aulacoseira sp. 1 and, to a lesser extent, C. aff. glomerata and A. ambigua. 5. Discussion
Diatom sedimentation commences at Lake Euramoo with an assemblage dominated by Aulacoseira ambigua, with Aulacoseira aff. perglabra as a sub-dominant. Much of this zone is characterised by a phase where no diatoms are preserved which ends abruptly with two samples dominated (N90% relative abundance) by A. aff. perglabra. The proportion of sediment organic matter, inferred by percentage loss-on-ignition at 550 °C (%LOI) exhibits a similar pattern to diatom preservation, with an initial increase and then sustained lower values between 664 and 694 cm. 4.2. Zone 3b (307–647 cm sediment depth, 2247– 1907 bws, 10,400–3340 cal. yr BP) Apart from the exception of infrequent samples (e.g. at 615, 423 and 307 cm) where Cyclotella aff. glomerata is dominant or subdominant and the occasional minor appearance of non-planktonic taxa, subzone 3b is overwhelmingly dominated by A. ambigua. 4.3. Zone 3a (209–307 cm sediment depth, 1907– 1809 cm bws, 3340–1560 cal. yr BP) Although A. ambigua dominates in all but the bottom sample in this subzone, its relative abundance is much
5.1. Late glacial variability A notable feature of the late glacial transition at Lake Euramoo is the strong correspondence between the preservation of diatoms and sediment organic matter. Diatom sedimentation in Lake Euramoo commences approximately 15,000 cal. yr BP as estimated organic content exceeds 40% for the first time, with samples dominated by A. ambigua and A. aff. perglabra as an important element. These data, in combination with abrupt declines in the swamp Cyperaceae and sediment magnetic susceptibility (Haberle, 2005), are indicative of the initial onset of relatively deep lake sedimentation. However, this inferred increase in lake level soon gives way to a period when loss on ignition falls below 40% and there is no diatom preservation (diatom samples from 664–688 cm depth inclusive). Although changes in loss on ignition can be interpreted in a number of different ways (Birks and Birks, 2006), we suggest that, in combination with the diatom data, suppressed %LOI values from 664 to 693 cm inclusive are indicative of reduced lake levels in response to reduced effective precipitation. Such an interpretation is supported by the re-expansion of Graminae and Casuarina at the commencement of this phase (Haberle, 2005). The contiguous
J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56
LOI data provide a considerably more precise estimate of the precise length of this period than the more coarsely sampled diatom data. Based on the age-depth relationship established in Haberle (2005), sediments were deposited between 11,500 and 13,800, a period which encompasses not only the Younger Dryas Chronozone but also much of the Antarctic Cold Reversal (Figs. 3 and 4). Sediments deposited at the end of the YDC are once again characterised by dominance of a centric diatom, A. aff. perglabra that are rapidly replaced by A. ambigua dominated assemblages. 5.2. Early through Mid Holocene stability Sediments 9500–4500 cal. yr old are characterised by a remarkable stability in the diatom community, with A. ambigua dominating all the assemblages N80% and, at times N 90% of all diatoms encountered. This constancy in the diatom community is, for the most part, reflected in the overall composition of the dryland vegetation communities which are largely dominated by rainforest (Fig. 3 and Haberle, 2005). The consistent representation of A. ambigua, in combination with sparse evidence of fringing vegetation (particularly up until 7000 cal. yr BP) suggests that lake levels, and by inference effective precipitation, at Lake Euramoo were highest during this period. Despite the consistency of this interpretation with high pollen inferred precipitation, particularly in the driest quarter (Kershaw and Nix, 1988), this interpretation must be viewed with some caution since A. ambigua appears to have been somewhat resilient to substantial inferred changes in late glacial hydrology at the site (see Section 5.1). By contrast to the inferred early to Mid Holocene stability in lake level, the fire record through this period is variable with, for example, the coarse charcoal fraction abundant until 7300 cal. yr BP. It appears that this burning had little or no influence on the diatom community, perhaps due to the major source of burning being outside the crater rim. 5.3. Increasing Mid to Late Holocene variability A peak in C. aff. glomerata (423 cm, 4500 cal. yr BP) signals the commencement of a period of increasing variability through the Late Holocene. In particular, after 3300 cal. yr BP, there is a variable transition from assemblages dominated by planktonic A. ambigua to those dominated by periphytic E. pectinalis (which is an abundant species in the fringing reed swamp of nearby Lake Barrine, Walker and Owen, 1999), suggestive of a fall in lake levels. The commencement of this phase (marked by the zone 3a-b boundary) is also associated
53
with key changes in indicators of catchment disturbance, with elevated occurrence of local fires and decreases in sediment organic content (as measured by %LOI), perhaps reflective of increase erosion. Kershaw and Nix (1988) suggest that at approximately this time (3.6 14C ka BP) there was a decline in mean annual precipitation, particularly that of the driest quarter. Certainly, such a change is consistent with inferred declines in lake level. While there is a clear consistency between these inferred climate-driven changes and proxy data from this and other sites (see Section 5.5), other factors may have also played a role. Infilling of the lake is likely to have increased potential habitat for periphytic diatoms. In particular, there have been substantial increases in the rate of accumulation of marginal sediments since the Mid Holocene (Kershaw, 1970) in areas which now support substantial fringing emergent and submerged macrophyte beds. While changes in habitat configuration may not be sufficient to explain the elimination of A. ambigua from the record, they are likely to have increased the sensitivity of the record to fluctuations in lake level. Similarly, other long-term lake and catchment evolution processes may have played a role. For example, the weathering of base cations through time can substantially reduce lake water pH (Engstrom et al., 2000). In this context, very low pH might explain the elimination of plankton (see Charles, 1985) with more moderate pH declines possibly driving the shift from A. ambigua to E. pectinalis. However, the rapid shifts in these taxa, the relatively high measured pH of the lake (Section 2) and, to a lesser extent, the similar optima for these taxa in south-east Australia (A. ambigua: 7.3, E. pectinalis: 6.9, Tibby et al., 2003) all suggest that this is unlikely to be the major mechanism driving this change. 5.4. Rapid environmental change: the last 1000 years Haberle et al. (2006) have documented the extent of European impact on the Lake Euramoo ecosystem and argued that, for a variety of indicators, the present state of the lake is outside the range of historic variability. The longer-term perspective provided in this study, while not contradicting these findings, indicates a somewhat more complex situation. As Tibby (2003) noted, post-European alterations in dominant taxa (E. pectinalis and Aulacoseira sp. 1) overlay a pattern of variability established for over 2000 years. Natural variability in these taxa means that detecting the precise timing of European-induced changes is difficult. Certainly, in terms of the diatom community, it now appears that the last 1000 years of Lake Euramoo's pre-contact history may have been the most variable in the Holocene (Fig. 4). Moreover, the character of this
54
J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56
variability was not merely fluctuations around a static mean, but rather is associated with distinct trends. Hence the increases in Aulacoseira sp. 1 and declines in E. pectinalis witnessed during the European period could be seen as either a part, or an accentuation, of trends which commenced approximately 700 years ago (Fig. 3). Haberle (2005) suggests that the expansion of a number of open water taxa, including Botryococcus and Nymphoides at the expense of Cyperaceae over the past 1000 years is suggestive of a return to open water conditions. Indeed the increased representation of Aulacoseira sp. 1, likely to be planktonic for part or all of its life cycle, in combination with minor increases in A. ambigua and C. aff. glomerata, at the expense of the periphytic diatom E. pectinalis is consistent with such an interpretation. 5.5. Local and regional patterns of climate variability Haberle (2005) has already demonstrated that sediments from Lake Euramoo substantially enhance the understanding of the environmental history of the wet tropics region by, for example, providing considerably earlier ages for rainforest expansion in response to climate amelioration. Whist the diatom record presented reinforces proxy data from this, and other, sites on the Atherton Tableland, it also highlights possible new relationships between the record from the site and regional scale climate processes. Perhaps most interestingly, the diatom data, in combination with contiguous estimated sediment organic content data provide new evidence for a “reversed” phase of elevated aridity between 13,800 and 11,500 cal. yr BP. During this period, around Lake Euramoo herbaceous taxa, in particular Graminae, and Casuarina dominated woodland, re-expand (Haberle, 2005). In nearby Lynch's Crater, 13,900 cal. yr BP is identified as a key point of change (Turney et al., 2006). However, wetter conditions are inferred to have commenced at 13,900 cal yr BP and become moister still from 12,600–11,600 cal. yr BP. The diatom data also highlight evidence for enhanced environmental variability commencing in the Mid Holocene and particularly from 3300 cal. yr BP where the dominance of A. ambigua gives way to E. pectinalis at a time of increased burning. Increases in sample resolution above 1 m sediment depth and sedimentation rates from approximately 2 m may accentuate this signal by both reducing the intra and inter sample time periods in the case of both and, in the case of the latter, by providing more suitable habitat for colonisation by nonplanktonic diatoms such as E. pectinalis. Despite this possibility, there is a general consistency between the
patterns observed and those in other indicators from the site. The habitat preferences A. ambigua (planktonic) and E. pectinalis (periphytic) are suggestive of a decline in lake levels (itself consistent with evidence for increased aridity from pollen and charcoal data, Kershaw and Nix, 1988; Haberle, 2005). The Late Holocene variability implied from these data is also reflected in Australian records beyond the Atherton Tableland. In southern Australia, data from the extensively studied closed lake basin Lake Keilambete suggest a period of marked variability commenced from between ca. 4000 14C yr BP (Chivas et al., 1993) and ca. 3500 14 C yr BP (Bowler, 1981), depending on the nature of the indicator used. However, by contrast to the pattern of continued last Holocene variability inferred for Lake Euramoo, this period of variation is argued to have ceased by 2500 14C yr BP in the grain size derived lake level record from Keilambete (Bowler, 1981) (with no ostracod shell chemistry based salinity inferences available for much of period post-2000 cal yr BP, Chivas et al., 1993). A compilation of southern Australian Holocene charcoal records suggests that landscape burning was higher in the period from 4000 years BP to European settlement than in the Early Holocene (Kershaw et al., 2001). More specifically, Stanley and DeDeckker (2002) suggest that the most variable part of the Holocene in south-eastern Australia was the last one and a half millennia, while in many ways the diatom record from Lake Euramoo is similar to the Holocene record from Lake Surprise, south-western Victoria. Tibby et al. (2006) suggest that from 3750 cal. yr BP, there is enhanced variability in climate as indicated by sustained high rates of change in diatom and pollen composition. Indeed, at Lake Surprise in a fashion similar to Lake Euramoo, Late Holocene diatom variability follows sustained high lake levels and is maintained until European arrival (Tibby et al., 2006). In terms of its relationship to global climate patterns, there is a broad coherence between the record from Lake Euramoo and general patterns of climate variation through the Holocene. In a compilation of global Holocene climate records (though notably which does not include any Australian records), Mayewski et al. (2004) show that the second half of the Holocene has been much variable than the first, with five of six identified periods of Holocene rapid climate change (RCC) occurring during the past 6000 cal. yr BP. More specifically, the generalised pattern of increased variability in the diatom record commencing ca. 3300 calibrated years before present suggests that it is only when modern El Niňo Southern Oscillation (ENSO) periodicities are sustained for a considerable length of time
J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56
(from 3500 cal. yr BP to 2500 cal. yr BP, see Moy et al., 2002a,b) that their effect is registered in this locality, with little response to the relatively short-lived period of intense variability from 4700 to 5100 cal. yr BP (Moy et al., 2002a,b). Such a conclusion is in agreement with the early attempt by McGlone et al. (1992) to deduce the history of ENSO from proxy data who suggest that while ENSO-type variability is notable from 5000 years before present, it is only after 3000 years that a pattern of variability similar to present is established. 6. Conclusion In combination with other lines of evidence, the diatom record from Lake Euramoo shows a generalised coherence with global patterns of climate change during the late glacial (with lacustrine conditions established between 14.5 and 15 cal kyr BP). However, interestingly, there is no direct correspondence between timing and duration of a newly described moisture reversal between 13,800 and 11,500 cal. yr BP and large-scale processes of ocean– atmosphere climate phenomena such as the Antarctic Cold Reversal or the Younger Dryas. Indeed, our results emphasise the complexity of late-glacial south-west Pacific environmental change which has been recently documented (Turney et al., 2006). Lake Euramoo also appears responsive to hemisphere-scale variability in the Holocene. The Late Holocene variability demonstrated in this study may provide at least a partial explanation for the “intensification” of land use and cultural practices by indigenous people in northern Australia (Lourandos and David, 2002); see Turney and Hobbs (2006) for further investigation and suggestions (sensu Tibby, 2003) that European occupation may have occurred at the time when the landscape was its most vulnerable for much or all of the Holocene. References Birks, H.H., Birks, H.J.B., 2006. Multi-proxy studies in palaeolimnology. Vegetation History and Archaeobotany 15, 235–251. Björck, S., Walker, M.J.C., Cwynar, L.C., Johnsen, S., Knudsen, K.-L., Lowe, J.J., Wohlfarth, B., INTIMATE Members, 1998. An event stratigraphy for the Last Termination in the North Atlantic region based on the Greenland ice-core record: a proposal by the INTIMATE group. Journal of Quaternary Science 13, 283–292. Blunier, T., Brook, E.J., 2001. Timing of millennial-scale climate change in Antarctica and Greenland during the last glacial period. Science 291, 109–112. Bowler, J.M., 1981. Australian salt lakes. A palaeohydrological approach. Hydrobiologia 82, 431–444. Bradbury, J.P., 1986. Late Pleistocene and Holocene paleolimnology of two mountain lakes in western Tasmania. Palaios 1, 381–388.
55
Charles, D.F., 1985. Relationships between surface sediment diatom assemblages and lake water characteristics in Adirondack Mountain (N.Y.) lakes. Ecology 66, 994–1011. Chivas, A.R., De Deckker, P., Cali, J.A., Chapman, A., Kiss, E., Shelley, J.M.G., 1993. Coupled stable-isotope and trace-element measurements of lacustrine carbonates as paleoclimatic indicators. In: Swart, P.K., Lohmann, K.C., McKenzie, J., Savin, S.M. (Eds.), Climate Change in Continental Isotopic Records. American Geophysical Union, Washington, pp. 113–121. Engstrom, D.R., Fritz, S.C., Almendinger, J.E., Juggins, S., 2000. Chemical and biological trends during lake evolution in recently deglaciated terrain. Nature 408, 161–166. Gell, P.A., 1997. The development of diatom database for inferring lake salinity, Western Victoria, Australia: towards a quantitative approach for reconstructing past climates. Australian Journal of Botany 45, 389–423. Gell, P.A., Barker, P.A., DeDeckker, P., Last, W.M., Jelicic, L., 1994. The Holocene history of West Basin Lake, Victoria, Australia: chemical changes based on fossil biota and sediment mineralogy. Journal of Paleolimnology 12, 235–258. Grimm, E.C., 1987. CONISS: a FORTRAN 77 program for stratigraphically constrained cluster analysis by the method of incremental sum of squares. Computers and Geosciences 13, 13–35. Haberle, S.G., 2005. A 23,000-yr pollen record from Lake Euramoo, Wet Tropics of NE Queensland, Australia. Quaternary Research 64, 343–356. Haberle, S.G., Tibby, J., Dimitriadis, S., Heijnis, H., 2006. The impact of European occupation on terrestrial and aquatic ecosystem dynamics in an Australian tropical rainforest. Journal of Ecology 94, 987–1002. Hendy, E., Gagan, M.K., Alibert, C.A., McCulloch, M.T., Lough, J.M., Isdale, P.J., 2002. Abrupt decrease in tropical pacific sea surface salinity at the end of the Little Ice Age. Science 295, 1511–1514. Jouzel, J., Vaikmae, R., Petit, J.R., Martin, M., Duclos, Y., Stievenard, M., Lorius, C., Toots, M., Mélières, M.A., Burckle, L.H., Barkov, N.I., Kotlyakov, V.M., 1995. The two-step shape and timing of the last deglaciation in Antarctica. Climate Dynamics 11, 151–161. Juggins, S., 2004. C2 Data Analysis. University of Newcastle, Newcastle. Kershaw, A.P., 1970. A pollen diagram from Lake Euramoo, northeast Queensland, Australia. New Phytologist 69, 785–799. Kershaw, A.P., 1974. A long continuous pollen sequence from northeastern Australia. Nature 251, 222–223. Kershaw, A.P., 1979. Local pollen deposition in aquatic sediments on the Atherton Tableland, North-Eastern Australia. Australian Journal of Ecology 4, 253–263. Kershaw, A.P., 1986. Climatic change and aboriginal burning in North-east Australia during the last two glacial/interglacial cycles. Nature 322, 47–49. Kershaw, A.P., Nanson, G.C., 1993. The last full glacial cycle in the Australian region. Global and Planetary Change 7, 1–9. Kershaw, A.P., Nix, H.A., 1988. Quantitative palaeoclimatic estimates from pollen data using bioclimatic profiles of extant taxa. Journal of Biogeography 15, 589–602. Kershaw, A.P., Clark, J.S., Gill, A.M., D'Costa, D.M., 2001. A history of fire in Australia. In: Bradstock, R.A., Williams, J.E., Gill, M.A. (Eds.), Flammable Australia. The Fire Regimes and Biodiversity of a Continent. Cambridge University Press, Cambridge, pp. 3–25. Krammer K., Lange-Bertalot H., 1986. Bacillariophyceae. 1: Teil: Naviculaceae. Gustav Fischer Verlag, Jena. Krammer K., Lange-Bertalot H., 1988, Bacillariophyceae. 2: Teil: Bacillariaceae, Epthimiaceae, Surirellaceae. Gustav Fischer Verlag, Jena.
56
J. Tibby, S.G. Haberle / Palaeogeography, Palaeoclimatology, Palaeoecology 251 (2007) 46–56
Krammer K., Lange-Bertalot H., 1991a. Bacillariophyceae. 3: Centrales, Fragilariaceae, Eunotiaceae. Gustav Fischer Verlag, Stuttgart. Krammer K., Lange-Bertalot H., 1991b. Bacillariophyceae. 4: Achnanthes, Kritische Ergänzunhen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4. Gustav Fischer Verlag, Stuttgart. Lourandos, H., David, B., 2002. Long-term archaeological and environmental trends: a comparison from late PleistoceneHolocene Australia. In: Kershaw, P., David, B., Tapper, N., Penny, D., Brown, J. (Eds.), Bridging Wallace's Line: The Environmental and Cultural History and Dynamics of the SE Asian-Australian Region. Catena, Reiskitchen, pp. 307–338. Mann, M., Bradley, R.S., Hughes, M.K., 1998. Global-scale temperature patterns and climate forcing over the past six centuries. Nature 392, 779–787. Mayewski, P.A., Rohling, E.E., Curt Stager, J., Karlen, W., Maasch, K.A., David Meeker, L., Meyerson, E.A., Gasse, F., van Kreveld, S., Holmgren, K., 2004. Holocene climate variability. Quaternary Research 62, 243–255. McGlone, M.S., Kershaw, A.P., Markgraf, V., 1992. El Nino/Southern Oscillation climatic variability in Australasian and South American paleoenvironmental records. In: Markgraf, V., Diaz, H. (Eds.), El Nino: Historical and Paleoclimatic Aspects of the Southern Oscillation. Cambridge University Press, Cambridge, pp. 435–462. Moy, C.M., Seltzer, G.O., Rodbell, D.T., Anderson, D.M., 2002a. Variability of El Nino/Southern Oscillation activity at millennial timescales during the Holocene epoch. Nature 420, 162–165. Moy, C.M., Seltzer, G.O., Rodbell, D.T., Anderson, D.M., 2002b. Laguna Pallcacocha Sediment Color Intensity Data, IGBP PAGES/ World Data Center for Paleoclimatology Data Contribution Series #2002-76. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. Reid, M.A., Tibby, J.C., Penny, D., Gell, P.A., 1995. The use of diatoms to assess past and present water quality. Australian Journal of Ecology 20, 57–64. Renberg, I., 1990. A procedure for preparing large sets of diatom slides from sediment cores. Journal of Paleolimnology 19, 399–416. Russell, D.J., 1987. Aspects of the limnology of tropical lakes in Queensland—with notes on their suitability for recreational fisheries. Proceedings of the Royal Society of Queensland 98, 83–91. Smol, J.P., Cumming, B.F., 2000. Tracking long-term changes in climate using algal indicators in lake sediments. Journal of Phycology 36, 986–1011. Stanley, S., DeDeckker, P., 2002. A Holocene record of allochthonous, aeolian mineral grains in an Australian alpine lake; implications for the history of climate change in southeastern Australia. Journal of Paleolimnology 27, 207–219.
Stuiver, M., Reimer, P.J., 1993. Extended 14C database and revised CALIB radiocarbon calibration program. Radiocarbon 35, 215–230. ter Braak, C.J.F., Šmilauer, P., 1999. Canoco for Windows Version 4.02. Wageningen, The Netherlands, Centre for Biometry, Wageningen. Tibby, J., 2003. Explaining lake and catchment change using sediment derived and written histories: an Australian perspective. Science of the Total Environment 310, 61–71. Tibby, J., 2004. Development of a diatom-based model for inferring total phosphorus in south-eastern Australian water storages. Journal of Paleolimnology 31, 23–36. Tibby, J., Reid, M., Fluin, J., Hart, B.T., Kershaw, A.P., 2003. Assessing long-term pH change in an Australian river catchment using monitoring and palaeolimnological data. Environmental Science & Technology 37, 3250–3255. Tibby, J., Kershaw, A.P., Builth, H., Philibert, A., White, C., 2006. Environmental change and variability in south-western Victoria: changing constraints and opportunities for occupation and land use. In: David, B., Barker, B., McNiven, I. (Eds.), The Social Archaeology of Australian Indigenous Societies. Aboriginal Studies Press, Canberra, pp. 254–269. Timms, B.V., 1976. Morphology of Lakes Barrine, Eacham and Euramoo, Atherton Tableland, north Queensland. Proceedings of the Royal Society of Queensland 87, 81–84. Tudor, E.R., 1973. Hydrological interpretation of diatom assemblages in two Victorian crater lakes. MSc. thesis, University of Melbourne, Melbourne. Turney, C., Hobbs, D., 2006. ENSO influence on Holocene Aboriginal populations in Queensland, Australia. Journal of Archaeological Science 33, 1744–1748. Turney, C.S.M., Kershaw, A.P., Clemens, S.C., Branch, N., Moss, P.T., Keith Fifield, L., 2004. Millennial and orbital variations of El Nino/Southern Oscillation and high-latitude climate in the last glacial period. Nature 428, 306–310. Turney, C.S.M., Kershaw, A.P., Lowe, J.J., van der Kaars, S., Johnston, R., Rule, S., Moss, P., Radke, L., Tibby, J., McGlone, M.S., Wilmshurst, J.M., Vandergoes, M.J., Fitzsimons, S.J., Bryant, C., James, S., Branch, N.P., Cowley, J., Kalin, R.M., Ogle, N., Jacobsen, G., Fifield, L.K., 2006. Climatic variability in the southwest Pacific during the Last Termination (20–10 kyr BP). Quaternary Science Reviews 25, 886–903. Vyverman, W., 1991. Diatoms from Papua New Guinea. Cramer, Berlin. Walker, D., Chen, Y., 1987. Palynological light on tropical rain forest dynamics. Quaternary Science Reviews 6, 77–92. Walker, D., Owen, J.A.K., 1999. The characteristics and source of laminated mud at Lake Barrine, Northeast Australia. Quaternary Science Reviews 18, 1597–1624.
