Fire and vegetation change during the Early Pleistocene in southeastern Australia

Early Pleistocene vegetation in upland southeastern Australia included diverse rainforests and sclerophyll forests, which alternated on precessional timescales. The nature and timing of transitions between these biomes, and the role of fire in maintaining or driving transitions between them, are uncertain. Here we present a high‐resolution pollen record from Stony Creek Basin, a small Early Pleistocene palaeolake in southeastern Australia. The pollen record documents a pattern of vegetation change, over ca. 10 ka at ca. 1590–1600 ka, between sclerophyll forests, dominated by Eucalyptus, Callitris (Cupressaceae) or Casuarinaceae, and rainforests dominated by either angiosperms or conifers of the family Podocarpaceae. Transitions between these biomes typically occurred within ca. 1–2 ka. The associated charcoal record suggests that greatest biomass combustion occurred when local vegetation was dominated by Eucalyptus, and the least biomass combustion occurred when local vegetation was dominated by Podocarpaceae. However, local fires burnt in both sclerophyll and angiosperm‐dominated rainforest vegetation, at least once every several centuries. Fire was very rare (less than about one fire per millennium) only when the local vegetation was rainforest dominated by Podocarpaceae. This suggests that fire was an irregular presence in both sclerophyll‐ and angiosperm‐dominated rainforest biomes during the late Neogene, though was largely absent in Podocarpaceae‐dominated rainforests. Copyright © 2011 John Wiley & Sons, Ltd.     

Plio‐Pleistocene landscape and vegetation reconstruction of the coastal area of the Tjörnes Peninsula,Northern Iceland

Marine and continental deposits from the Tjörnes area in northern Iceland were studied to obtain their pollen/spore content. Six Pollen Zones (PZ) were defined in the Early Pliocene Tjörnes beds and the Early Pleistocene Breidavík Group. The pollen is most diverse during the deposition of the lowest Tapes Zone (PZ 1) and the lower part of the overlying Mactra Zone (PZ 2). Local pollen from marshland, levee and foothill forests was deposited on a large coastal plain. The pollen spectrum reflects transgression and deepening during the second part of the Mactra Zone (PZ 3) and the lower part of the Serripes Zone (PZ 4). Gymnosperm pollen derived from the higher inland plateau increases in PZ 3. This background pollen was of minor importance during periods with an extensive coastal plain (PZ 1, 2, 4, 6). PZ 5 did not yield sufficient pollen for analysis. The pollen analysis allowed refinement of the sea‐level variations based on sedimentology and molluscs. Pollen of warmth‐demanding plants is recorded throughout the Tjörnes beds and the Early Pleistocene interglacial deposits. Warmth‐loving species indicate summers 8°C warmer than today during deposition of the Tapes Zone, and at least 5°C warmer during the rest of the Tjörnes beds. The Pliocene vegetation of Iceland matches well that of the present‐day western European maritime temperate climate. The drastic cooling at the onset of the Quaternary led to a marked vegetation impoverishment, already noticeable in the Early Pleistocene Breidavík Group.     

A late Early Pleistocene pollen record from Fontana Ranuccio (central Italy)

A pollen record from a sediment core drilled underneath the Acheulian site of Fontana Ranuccio provides new data on the vegetation characters in central Italy during the late Early Pleistocene, in a forest phase possibly corresponding to a substage of Marine Isotope Stage 21. A number of tree taxa nowadays extinct in Europe (Cathaya, Tsuga, Taxodium type, Carya and Pterocarya) are present at Fontana Ranuccio in a temperate phase characterised by dense forest conditions, dominated by Alnus and Pterocarya. The comparison of the Fontana Ranuccio record with other dated sites distributed along the Italian peninsula indicates that the floristic and vegetational characters of the Mid Pleistocene revolution present a rather distinct succession of biostratigraphic events. Compared to other Early Pleistocene pollen records from southern Europe, the Italian Peninsula shows greater floristic similarities with the Eastern Mediterranean regions than with the Iberian Peninsula. Copyright © 2011 John Wiley & Sons, Ltd.     

The impact of summer temperature changes on vegetation development in Ireland during the Weichselian Lateglacial Interstadial

We analysed pollen from a sediment core from Fiddaun, a small Lateglacial lake basin in western Ireland. Results reflect the general Lateglacial vegetation development in Ireland, as reconstructed from other pollen records. The Fiddaun diagram shows a number of short‐lived regressive vegetation phases during the Interstadial. The close similarity between two pollen records from the same region (Fiddaun and Lurga) indicates that these fluctuations probably reflect regional rather than local changes. Comparison with a previously published climate reconstruction, based on a chironomid‐inferred mean July air temperature reconstruction, lithology, and oxygen and carbon isotopes of lake marl from the Fiddaun record, allowed us to establish the relationship between summer temperature and vegetation changes. Results reveal that two temporary regressive shifts in the pollen record correspond to cold oscillations, which have been correlated to Greenland Interstadial 1b and 1d. It seems that the first cold oscillation (GI‐1d) had the most distinct effect on vegetation in Ireland. In contrast, it appears that the transition from Juniperus shrubland and Empetrum heath to grassland, which is estimated at ～13.7 ka BP, was not caused by decreasing summer temperatures, as no substantial change is observed in the climate proxies. Copyright © 2012 John Wiley & Sons, Ltd.     

Late Quaternary vegetation,climate and fire dynamics inferred from the El Tiro record in the southeastern Ecuadorian Andes

In order to study the stability and dynamics of mountain rainforest and paramo ecosystems, including the biodiversity of these ecosystems, the Holocene and late Pleistocene climate and fire variability, and human impact in the southeastern Ecuadorian Andes, we present a high‐resolution pollen record from El Tiro Pass (2810 m elevation), Podocarpus National Park. Palaeoenvironmental changes, investigated by pollen, spores and charcoal analysis, inferred from a 127 cm long core spanning the last ca. 21 000 cal. yr BP, indicate that grass‐paramo was the main vegetation type at the El Tiro Pass during the late Pleistocene period. The grass‐paramo was rich in Poaceae, Plantago rigida and Plantago australis, reflecting cold and moist climatic conditions. During the early Holocene, from 11 200 to 8900 cal. yr BP, subparamo and upper mountain rainforest vegetation expanded slightly, indicating a slow warming of climatic conditions during this period. From 8900 to 3300 cal. yr BP an upper mountain rainforest developed at the study site, indicated by an increase in Hedyosmun, Podocarpaceae, Myrsine and Ilex. This suggests a warmer climate than the present day at this elevation. The modern subparamo vegetation became established since 3300 cal. yr BP at El Tiro Pass. Fires, probably anthropogenic origin, were very rare during the late Pleistocene but became frequent after 8000 cal. yr BP. Copyright © 2007 John Wiley & Sons, Ltd.     

Vegetation context and climatic limits of the Early Pleistocene hominin dispersal in Europe

The vegetation and the climatic context in which the first hominins entered and dispersed in Europe during the Early Pleistocene are reconstructed, using literature review and a new climatic simulation. Both in situ fauna and in situ pollen at the twelve early hominin sites under consideration indicate the occurrence of open landscapes: grasslands or forested steppes. The presence of ancient hominins (Homo of the erectus group) in Europe is only possible at the transition from glacial to interglacial periods, the full glacial being too cold for them and the transition interglacial to glacial too forested. Glacial–interglacial cycles forced by obliquity showed paralleled vegetation successions, which repeated c. 42 times during the course of the Early Pleistocene (2.58–0.78 Ma), providing 42 narrow windows of opportunity for hominins to disperse into Europe.The climatic conditions of this Early Pleistocene vegetation at glacial-interglacial transitions are compared with a climatic simulation for 9 ka ago without ice sheet, as this time period is so far the best analogue available. The climate at the beginning of the present interglacial displayed a stronger seasonality than now. Forest cover would not have been hampered though, clearly indicating that other factors linked to refugial location and soils leave this period relatively free of forests. Similar situations with an offset between climate and vegetation at the beginning of interglacials repeated themselves throughout the Quaternary and benefitted the early hominins when colonising Europe.The duration of this open phase of vegetation at the glacial–interglacial transition was long enough to allow colonisation from the Levant to the Atlantic.The twelve sites fall within rather narrow ranges of summer precipitation and temperature of the coldest month, suggesting the hominins had only a very low tolerance to climate variability.     

First lake record of Holocene climate and vegetation change of the Northern Kuril Islands

Investigation of Pernatoe Lake sediments in the south of Paramushir Island has enabled us to obtain the first continuous pollen record of climate and vegetation changes in the north of the Kurile archipelago during the Holocene. Series of radiocarbon datings of between 10 000 ± 40 and 2180 ± 40 years ago are evidence that the beginning of sediments accumulation, found after borehole development, is related to the Early Holocene. Diatom analysis has shown several stages in the lake development: raised bog on the border of the Pleistocene and Holocene, lagoon formation resulting from the sea level rise over 9–6 ky, and freshwater lake formation 6 ky and up to the present. Climate warming during the period attributed to the boreal and Atlantic periods of the Holocene is reflected by the dominance of Pinus pumila and Alnus serrulata assemblages in vegetation cover. Wide dune fields were formed in the Sea of Okhotsk and the Pacific shores of Paramushir Island 5–4 ky. Strengthening of atmogenic processes is related to cooling of the climate and drying of some areas of the underwater slope.     

Plio-Pleistocene geological record and small mammal faunas, eastern shore of the Azov Sea, Southern European Russia

The shoreline of the Taganrog Gulf of the Azov Sea at the mouth of Don River provides a series of extended Upper Pliocene and Quaternary sections that have been actively studied in the last century. This extraglacial region had a complex sedimentary history combining subaerial aggradation with marine, fluvial, and deltaic sedimentation. The well-exposed stratigraphical sequence and abundant palaeontological record continuously attract geologists and highlight the region as one of international importance for the addressing of numerous problems of Late Pliocene and Quaternary stratigraphy and palaeogeography. Fossil mammalian faunas of the region include important Eurasian biostratigraphical markers such as Stenocranius ex gr. hintoni-gregaloides, Lagurini spp., and Mimomys savini. For many years, fossil remains of mammals provide decisive clues to the geological history of the region. Recent geological studies of reference sections have provided data on small mammals, palaeomagnetism and palaeogeographical reconstructions in the northeastern part of the Azovian Region. Mammalian assemblages indicate the presence of the Late Pliocene, late Early Pleistocene, Middle Pleistocene and Late Pleistocene levels and, in addition, provide a clear biostratigraphical context for the Early Middle Pleistocene transition.     

An 11 000-year record of vegetation and environment from Lago di Martignano,Latium, Italy

A pollen diagram from Lago di Martignano, a maar lake in central Italy, provides an 11000-year record of vegetation and environment change. The earliest pollen spectra are dominated by Artemisia and Gramineae, representing late glacial steppe vegetation typical of the Mediterranean region. Broad-leaved forests were established by ca. 11 000 yr BP. Although Quercus initially dominated their canopy, a wide range of other mesophyllous trees were also present. Pollen values for sclerophyllous tree and shrub taxa characteristic of Mediterranean woodlands and scrub are initially low (<10%). After ca. 7000 yr BP, however, they begin to increase and rise to a peak of >40% of total land pollen at ca. 6700 yr BP, with Olea europaea the single most abundant taxon. Human influence upon the vegetation only becomes significant somewhat after this peak, with progressive clearance of woodland and expansion of herbaceous communities. Castanea sativa and luglans regia pollen is recorded consistently from the beginning of the rise in pollen values for taxa characteristic of Mediterranean scrub communities. Pollen values for arable crops increase progressively after ca. 5500 yr BP, following the peak pollen values for taxa characteristic of Mediterranean scrub vegetation. Late glacial and Holocene climate changes have been complex in this region, with the present character of the climate developing only during the last millennium. Rates of change of pollen spectra peak during this period.     

Vegetation and climate changes in northwestern Russia during the Lateglacial and Holocene inferred from the Lake Ladoga pollen record

The new pollen record from the upper 12.75 m of a sediment core obtained in Lake Ladoga documents regional vegetation and climate changes in northwestern Russia over the last 13.9 cal. ka. The Lateglacial chronostratigraphy is based on varve chronology, while the Holocene stratigraphy is based on AMS ¹⁴C and OSL dates, supported by comparison with regional pollen records. During the Lateglacial (c. 13.9–11.2 cal. ka BP), the Lake Ladoga region experienced several climatic fluctuations as reflected in vegetation changes. Shrub and grass communities dominated between c. 13.9 and 13.2 cal. ka BP. The increase in Picea pollen at c. 13.2 cal. ka BP probably reflects the appearance of spruce in the southern Ladoga region at the beginning of the Allerød interstadial. After c. 12.6 cal. ka BP, the Younger Dryas cooling caused a significant decrease in spruce and increase in Artemisia with other herbs, indicative of tundra‐ and steppe‐like vegetation. A sharp transition from tundra‐steppe habitats to sparse birch forests characterizes the onset of Holocene warming c. 11.2 cal. ka BP. Pine forests dominated in the region from c. 9.0 to 8.1 cal. ka BP. The most favourable climatic conditions for deciduous broad‐leaved taxa existed between c. 8.1 and 5.5 cal. ka BP. Alder experiences an abrupt increase in the local vegetation c. 7.8 cal. ka BP. The decrease in tree pollen taxa (especially Picea) and the increase in herbs (mainly Poaceae) probably reflect human activity during the last 2.2 cal. ka. Pine forests have dominated the region since that time. Secale and other Cerealia pollen as well as ruderal herbs are permanently recorded since c. 0.8 cal. ka BP.     

Late Pleistocene vegetation of Kings Canyon,Sierra Nevada,California

Seven packrat midden samples make possible a comparison between the modern and late Pleistocene vegetation in Kings Canyon on the western side of the southern Sierra Nevada. One modern sample contains macrofossils and pollen derived from the present-day oak-chaparral vegetation. Macrofossils from the six late Pleistocene samples record a mixed coniferous forest dominated by the xerophytic conifers Juniperus occidentalis, Pinus cf. ponderosa, and P. monophylla. The pollen spectra of these Pleistocene middens are dominated by Pinus sp., Taxodiaceae-Cupressaceae-Taxaceae (TCT), and Artemisia sp. Mesophytic conifers are represented by low macrofossil concentrations. Sequoiadendron giganteum is represented by a few pollen grains in the full glacial. Edaphic control and snow dispersal are the most likely causes of these mixed assemblages.The dominant macrofossils record a more xeric plant community than those that now occur on similar substrates at higher elevations or latitudes in the Sierra Nevada. These assemblages suggest that late Wisconsin climates were cold with mean annual precipitation not necessarily greater than modern values. This conclusion supports a model of low summer ablation allowing for the persistence of the glaciers at higher elevations during the late Wisconsin. The records in these middens also suggest that S. giganteum grew at lower elevations along the western side of the range and that P. monophylla was more widely distributed in cismontane California during the Pleistocene.     

Late Pleistocene and Holocene Afromontane vegetation and headwater wetland dynamics within the Eastern Mau Forest,Kenya

The Mau Forest Complex is Kenya's largest fragment of Afromontane forest, providing critical ecosystem services, and has been subject to intense land use changes since colonial times. It forms the upper catchment of rivers that drain into major drainage networks, thus supporting the livelihoods of millions of Kenyans and providing important wildlife areas. We present the results of a sedimentological and palynological analysis of a Late Pleistocene–Holocene sediment record of Afromontane forest change from Nyabuiyabui wetland in the Eastern Mau Forest, a highland region that has received limited geological characterization and palaeoecological study. Sedimentology, pollen, charcoal, X-ray fluorescence and radiocarbon data record environmental and ecosystem change over the last ~16 000 cal a bp. The pollen record suggests Afromontane forests characterized the end of the Late Pleistocene to the Holocene with dominant taxa changing from Apodytes, Celtis, Dracaena, Hagenia and Podocarpus to Cordia, Croton, Ficus, Juniperus and Olea. The Late Holocene is characterized by a more open Afromontane forest with increased grass and herbaceous cover. Continuous Poaceae, Cyperaceae and Juncaceae vegetation currently cover the wetland and the water level has been decreasing over the recent past. Intensive agroforestry since the 1920s has reduced Afromontane forest cover as introduced taxa have increased (Pinus, Cupressus and Eucalyptus).     

Magnetostratigraphic dating of an intensification of glacial activity in the southern Italian Alps during Marine Isotope Stage 22

We applied magnetostratigraphy and mammal biostratigraphy to date climate-sensitive pollen cycles and lithostratigraphic units of the Pliocene-Pleistocene Leffe sedimentary succession from the Southern Alps, Italy. The Leffe section was correlated to additional sections (Casnigo, Fornaci di Ranica, and Pianengo) to construct a stratigraphic network along a common fluviatile system (the Serio River) sourced in the Southern Alps and flowing southward into the Po River Basin. We obtained a coherent scenario of climate variability for the last ∼ 2 Myr. At Leffe, lacustrine deposition commenced during the Olduvai Normal Subchron (1.94-1.78 Ma) and lasted up to a chronologic level compatible with Marine Isotope Stage (MIS) 22 (0.87 Ma). Pollen analysis revealed that climate varied cyclically from warm-temperate to cool during this time interval, but never as cold as during glacial intervals. At around MIS 22, climate cooled globally. Gravels, attributed to high-energy braided river systems fed locally by alluvial fans, prograded from the Serio River catchment area over the Leffe Basin and toward the Po Plain in response to a generalized event of vegetation withdrawal and enhanced physical erosion. At this time, Alpine valley glaciers reached their first maximum southward expansion with glacier fronts located at only ∼ 5 km upstream from Leffe.     

哺乳动物群指示的气候旋回——以周口店早更新世哺乳动物群为例

文章根据对周口店地区四个哺乳动物群的分析，讨论了该区早更新世气候及生态环境的变迁。第１８地点显示了约１．９０ＭａＢ．Ｐ．的干凉气候和森林—草原植被。第１２地点指示了１．７０ＭａＢ．Ｐ．的湿热气候和茂密森林生态环境。东洞则记录了１．２０ＭａＢ．Ｐ．的干冷气候和草原景观。到第９地点时（约１．００～０．９０ＭａＢ．Ｐ．），气候炎热，森林和草原植被同时发育     

华北地块东北缘红庙子盆地鹰嘴砬子组孢粉化石

报道华北地块东北缘地区红庙子盆地鹰嘴砬子组的孢粉化石,建立了Cicatricosisporites-Abietineaepollenites-Piceites组合,该组合的主要特征为:以裸子类双气囊花粉和海金沙科孢子为主,含一定量裸子类无气囊花粉,未见被子类花粉,孢粉组合特征可与松辽盆地沙河子组对比。一些具有早白垩世时代意义的孢粉化石,如Cicatricosisporites sp.,Cicatricosisporites undulates和Cicatricosisporites implexus的出现,表明鹰嘴砬子组的地质时代为早白垩世。根据孢粉化石资料,推测华北地块东北缘地区在鹰嘴砬子组沉积时期古植被面貌以松科和杉科组成的松柏类针叶林为主,林下生长着真蕨类。古气候相当于湿润-半湿润的亚热带气候。     

Middle Wisconsin stratigraphy and climatic reconstruction,southern Vancouver Island,British Columbia

Interbedded, organic-rich terrestrial and marine sediments exposed along the eastern coastal lowland of Vancouver Island contain an almost continuous record of middle Wisconsin vegetation and climate. The record has been interpreted largely from palynostratigraphic studies at three sites and supported by a study of modern pollen spectra from the three major biogeoclimatic zones of the extant vegetation. Radiocarbon dates from a variety of organic materials in the middle Wisconsin beds reveal that the fossil pollen spectra span an interval ranging from approximately 21,000 yr B.P. to more than 51,000 yr B.P. The spectra are divided into eight major pollen zones encompassing the Olympia Interglaciation and early Fraser Glaciation geologicclimate units of the Pacific Northwest. The Olympia Interglaciation extended from before 51,000 yr B.P. to ca. 29,000 yr B.P. and was characterized by a climate similar to present. During the early Fraser Glaciation, from 29,000 years ago to approximately 21,000 yr B.P., climate deteriorated until tundra like conditions prevailed. These pollen sequences are correlative with those of coastal British Columbia and partly with those from Olympic Peninsula, but apparently are not comparable with events in the Puget Lowland.     

Lithostratigraphical correlation of micromammal sites and biostratigraphy of the Upper Pliocene to Lower Pleistocene in the Northeast Guadix‐Baza Basin (southern Spain)

The Plio‐Pleistocene non‐marine sequence in the northeast Guadix–Baza Basin (southern Spain) comprises alluvial and lacustrine deposits (Baza Formation). The results of a revised lithostratigraphical correlation between sections from the middle and upper members of the Baza Formation in the northeast part of the basin, supported by detailed mapping, is presented. The position of micromammal sites in the lithostratigraphical scheme, together with the results of intensive palaeontological sampling for small mammal remains, has allowed us to develop a high‐resolution biostratigraphical framework for the area. This provides an opportunity to refine the biozonation for the Plio‐Pleistocene micromammal faunas, and to define faunal events from the late Villanyian (late Pliocene) to the early Pleistocene. On the basis of the lithostratigraphical and biostratigraphical approaches we obtain the following sequence of biozones for the late Pliocene to early Pleistocene: Kislangia gusii, Mimomys cf. reidi, M. oswaldoreigi, Allophaiomys pliocaenicus and A. burgondiae. Copyright © 2000 John Wiley & Sons, Ltd.     

Synchronization of late-glacial vegetation changes at Crystal Lake, Illinois, USA with the North Atlantic Event Stratigraphy

Late-glacial (17–11 cal ka BP) pollen records from midwestern North America show similar vegetation trends; however, poor dating resolution, wide-interval pollen counts, and variable sedimentation rates have prevented the direct correlation with the North Atlantic Event Stratigraphy as represented in the Greenland ice-core records, thus preventing the understanding of the teleconnections and mechanisms of late-Quaternary events in the Northern Hemisphere. The widespread occurrence of late-glacial vegetation and climates with no modern analogs also hinders late-glacial climate reconstructions. A high-resolution pollen record with a well-controlled age model from Crystal Lake in northeastern Illinois reveals vegetation and climate conditions during the late-glacial and early Holocene intervals. Late-glacial Crystal Lake pollen assemblages, dominated by Picea mariana and Fraxinus nigra with lesser amounts of Abies and Larix, suggest relatively wet climate despite fluctuations between colder and warmer temperatures. Vegetation changes at Crystal Lake are coeval with millennial-scale trends in the NGRIP ice-core record, but major shifts in vegetation at Crystal Lake lag the NGRIP record by 300–400 yr. This lag may be due to the proximity of the Laurentide ice sheet, the ice sheet's inherent slowness in response to rapid climate changes, and its effect on frontal boundary conditions and lake-effect temperatures.     

Holocene vegetation and climate fluctuations in northwest Himalaya,based on pollen evidence from Surinsar Lake,Jammu region,India

Pollen analysis of a 33.21 m deep sediment core from Surinsar lake in Jammu region has revealed that between 9,500 and 7,700 yr BP (Pollen zone SL-I), the mixed oak-broad-leaved/chirpine forest occurred in the region under a warm and humid climate. The record of aquatic plants viz. Potamogeton, Typha and freshwater alga Botryococcus in appreciable numbers denotes the existence of the lake since the Early Holocene. Subsequently, mixed chirpine/oak-broad-leaved forests appeared in the area around 7,700 to 6,125 yr BP (Pollen zone SL-II) with the dominance of chirpine (Pinus cf. roxburghii) by the onset of cool and dry climate, attributed to decrease in monsoon rainfall. The expansion of oak and its broad-leaved associates between 6,125 and 4,330 yr BP (Pollen zone SL-III) suggests that the climate turned moderately humid and warm, presumably due to enhanced monsoonal effect. The region has witnessed a brief spell of pluvial environment between 4,330 and 4,000 yr BP (Pollen zone SL-IV) as evidenced by the presence of sandy layer at 15.4–14 m depths. The period of 4,000 to 2,100 yr BP (Pollen zone SL-V) is marked by the prevalence of cool and dry climate as depicted by a sharp decline in oak (Quercus cf. incana) and other broad-leaved taxa and a concurrent increase in chirpine. From 2,100 to 800 yr BP (Pollen zone SL-VI) no palaeofloristic inferences could be drawn due to paucity of pollen, however, the presence of sandy deposit at the corresponding level in lithocolumn implies a pluvial episode by this time. Since 800 yr BP to Present (Pollen zone SL-VII) the slight advance in the oak reflects the ameliorating trend of climate, despite the existing cool and dry climate.     

Vegetation and climates in southern Tasmania since the last glaciation

Enclosed basins (glacial and nonglacia) of Tasmania contain the most comprehensive record in Australia of trends in a regional vegetation and climate since the late Pleistocene. Seven pollen sequences, each continuous and extending back at least 10,000 years, are used to reconstruct the history of postglacial vegetation and climate in Southern Tasmania (42°S–43°30′S). Interpretations are supported by a study of the modern pollen rain. Postglacial climates in Tasmania were characterized by a strong west-to-east decrease in precipitation. During the late Pleistocene, climates were markedly colder and drier than at present, and the vegetation was largely devoid of trees. A major rise in temperature between ca. 11,500 and 9500 yr B.P., accompanied by rising effective precipitation, resulted in the expansion of Eucalyptus, then other trees, across Tasmania. This warming trend may have been temporarily reversed during the early postglacial. Dry climates delayed the development of forest in inland eastern Tasmania until after ca. 9500 yr B.P. There is no evidence for a major change in climate since this temperature rise. Two broad phases of development have occurred within the postglacial forests. The first was an early Holocene phase during which Nothofagus cunninghamii cool temperate rain forest developed in western Tasmania and on the slopes of mountains in central and southeastern Tasmania. Eucalyptus sclerophyll forests developed in eastern Tasmania and have remained dominant there since. By ca. 7800 yr B.P. rain-forest communities were established beyond present-day limits. The second phase was a mid to late Holocene phase during which forests and alpine vegetation became more open in structure, leading to the re-expansion of Eucalyptus and shade-intolerant species. During the early to mid Holocene, climates in Southern Tasmania were wetter and (? then) warmer than at present. Maximum and minimum dates for this “optimum” are 8000 and 5000 yr B.P. Since then, climates have become increasingly rigorous, possibly through an increased incidence of inequable “weather types” leading to an increase in the frequency of drought and frost. Structural changes in the postglacial vegetation of Southern Tasmania closely parallel those at equivalent latitudes in New Zealand and Chilean South America, hence are likely to reflect the same primary cause.