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• Holocene vegetational dynamics along the prairie–forest border of Minnesota were first documented in McAndrews’ classic work. Despite numerous subsequent paleo-studies, a number of questions remain unanswered about the vegetation history of the region. Here, pollen, stable-isotope, mineral, and charcoal data are described from three lakes near McAndrews’ sites. These data were compared with other paleoenvironmental records to reconstruct vegetation, aridity, and fire. • The climate was relatively wet with increasing summer temperatures before ~8000 yr before present (BP). The rates of changes were asymmetric for the onset and termination of middle-Holocene aridity, with an abrupt increase at ~8000 yr BP and a gradual, but variable, decline from ~7800 to 4000 yr BP. • Early-Holocene coniferous forests changed to mixed-grass prairie without an intervening period of tallgrass prairie or deciduous forest, whereas the retreat of prairie was characterized by transitions from mixed-grass to tallgrass prairie to deciduous forest and finally to coniferous forest. Within the middle Holocene, the composition and structures of grass-dominated vegetation varied both temporally and spatially. • Fire primarily responded to changes in climate and fuel loads. Vegetation was more strongly influenced by climatic changes than by fire-regime shifts. [ABSTRACT FROM AUTHOR]

Palaeoecological investigations of two lake sediment sequences art used to reconstruct the vegetation history of the Western Isles. Pollen records begin in the late glacial and show a clear progression from herb-rich grassland with abundant Salix. Rumex and Polypodium to widespread Empetrum nigrum heath. Woodland developed widely in the early Holocene, and regional vegetation patterns emerged. Western Lewis supported extensive areas of birch woodland with Corylus avellana, Salix, Populus and Sorbus aucuparia. Open birch-hazel woodland dominated other lowland regions. Regional variation was accentuated when woodland underwent a sudden decline in western Lewis at about 7900 BP. Trees were replaced by blanket peat and woodland failed to recover on a regional scale after the decline. Woodland continued to diversify in central and eastern regions and, by 6000 BP, Quercus, Ulmus, Pinus sylvestris, Alnus glutinosa and Fraxinus excelsior had become established. Open mixed woodland persisted until the second major decline began between 5200 and 4000 BP. Woodland contracted gradually as blanket peat expanded. The Western Isles were predominantly treeless at 2500 BP. Blanket peat started to form in localized areas on the Western Isles between 9000 and 8000 BP; two main expansion phases are associated with periods of woodland decline. Subfossil wood or macrofossils are reported from a total of 40 sites. Radiocarbon ages are presented for 13 samples of these. [ABSTRACT FROM AUTHOR]

A radiocarbon dated pollen and macrofossil record from Lang Lochs Mire, Shetland, is presented. Late-glacial minerogenic and early Holocene gyttja sediments underlie mid and lute Holocene peat. These indicate that the area was free from ice sometime before 13000 BP and there is evidence for a typical Devensian Late-glacial climatic sequence as recorded elsewhere in Scotland. Until c. 10500 BP an open vegetation with abundant mosses amongst dwarf shrubs and herbs characterized the surrounding area. At c. 10500 BP gyttja deposition starred, aquatic plants became abundant in the loch and Betula woodland developed around the loch. From c. 9700 BP to c. 7700 BP Corylus was also important. During this time Alnus, Quercus and Ulmus pollen values rose but remained compatible with a long distance source for the pollen. At c. 7700 BP gyttja deposition ceased at the sample site and a poor fen developed. Around this, heathland and blanket peat vegetation started to develop from c. 7000 BP. By c. 6000 BP the area was largely treeless and after c. 5000 BP blanket peat spread and eventually dominated all but the steepest slopes. Pollen profile changes after c. 4500 BP can be attributed to either the spread of blanket peat or the effects of Neolithic peoples. The changes coincide with the arrival of Neolithic people elsewhere in Shetland. The first clear indication of Neolithic activity is dated to c. 3000 BP and coincides with increased activity in agriculturally more favourable areas of Shetland. Records of phytogeographically significant species are discussed and the value of combined macrofossil and pollen investigations is illustrated. The combined approach has helped to distinguish site and regional components of the pollen rain, the vegetational development of both the site and the surrounding area and has given a more accurate record of the occurrence of a number of taxa than could be achieved by pollen analysis alone. [ABSTRACT FROM AUTHOR]

Two swamp sites on Flinders Island in Bass Strait provide evidence of vegetation cover for the period 10000 BP to present. Steppe vegetation in which Compositae Liguliflorae taxa and chenopods were important was present on the Flinders Island part of the Bassian Isthmus during the earliest part of the record. However, it was replaced by eucalypt forest or woodland with a grassy understorey and some shrubs as sea level rose to form the present island by 6000 BP. The eucalypt dominated vegetation became less important about 940 BP when Callitris became prominent until very recently. This change may be related to a drier climate. Hinders Island is one of the few sites in Australia where humans were absent for an extended time (c. 4700 to 200 BP) during the Holocene. There is no particular indication of pollen or charcoal changes which can be related to the disappearance of humans from the island. However, at Killiecrankie Swamp the arrival of Europeans 200 yr ago probably caused the increased charcoal input to the swamp sediments and the vegetation change observed. Likewise Middle Patriarch Swamp records changes due to clearing and swamp drainage in the most recent times. The fact that the swamp deposits contain charcoal and pollen, together with the density of swamps on the eastern side of the island means the area is very favourably placed to provide detailed information on firing regimes unaffected by humans, in a sclerophyll vegetation very similar to that in large areas of southeastern Australia. In the light of the pollen evidence from this study and that from other southeastern mainland and Tasmanian sites it is suggested that the apparent prominence of Casuarina in the southwest of Victoria and southeast of South Australia during the early Holocene was due to local soil factors and drier climate. Later changes in soil and climate led to a decrease in Casuarina and increase in Eucalyptus. [ABSTRACT FROM AUTHOR]

The pollen-analytical study of eight sites (two glacial lakes and six coastal marshes) has been carried out (nine pollen diagrams, 472 pollen spectra). The total absence of Quercus ilex forest in Corsica during the Atlantic and the vegetation contrast existing at that time between the western and the eastern sides of the island are demonstrated. On the western site, Erica arborea constituted the only regional vegetation from the coast up to about 1500 m. Human action is responsible for the establishment of Quercus ilex in this climax vegetation during the Sub-boreal. It is also shown that the only Pinus halepensis forest present today in Corsica has been introduced on the island during the nineteenth century. [ABSTRACT FROM AUTHOR]

A Holocene record of pollen, charcoal, magnetic susceptibility and sediment chemistry from South Uist, Western Isles, is described and discussed. The vegetation of eastern South Uist included areas of woodland over as much as half of the available landscape during the early postglacial. This woodland was dominated by Betula and Corylus, but Quercus, Ulmus, Alnus glutinosa and Fraxinus excelsior were also present. The status of Pinus sylvestris is uncertain. Quercus, Ulmus and A. glutinosa are now extinct as native trees in the Western Isles. During the later half of the Holocene (from about 4000 HP), woodland declined, possibly as a result of the use of hill land as grazing. Blanket peat vegetation, which had begun to spread from about 5500 BP, became the dominant feature of the landscape as the woodland areas decreased. The physical and chemical data from Loch Lang sediments Suggest that little erosion of soils took place until about 550 years ago, when there was a marked increase, possibly attributable to increasing grazing pressure. [ABSTRACT FROM AUTHOR]

Pollen analysis and 14C dating of 5.5 m of organic-rich soil and fluviatile deposits from Newall Creek (altitude 140 m) indicate that temperate rainforest (0-11 K yr B.P.) was preceded by grassland-herbland (11 to 21 K yr B.P.), and then by open grassy Eucalyptus woodland. Comparison with a lake-swamp site at Tullabardine Dam showed that the main vegetation changes were comparable making allowance for some spatial variations in the taxa represented and the lower quantity of pollen in the fluviatile deposits. The inferred sequence of climatic change was from a cool moist interstadial through a cold last glacial maximum to a warm moist Holocene environment, a sequence also indicated at Tullabardine. [ABSTRACT FROM AUTHOR]

Two new Holocene pollen diagrams are presented from central East Anglia. Using these sites and others from the same area, regional pollen assemblage-zones for the area are formally defined. The regional pollen assemblage- zones are then combined with zones from other well-dated sequences in the British Isles to produce time/space diagrams for vegetation history along three transects across the islands. It is shown that pollen assemblage-zones have only a limited extent in time and space. Forest vegetation has varied almost continually in time and space throughout the Holocene and over the whole of the British isles. [ABSTRACT FROM AUTHOR]