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New pollen, phytolith, charcoal and diatom data from 14C AMS-dated sediments from three clusters of former occupation sites on the southern Yangtze Delta – Liangzhu, Majiabang and Chuodun – reveal that hydrological conditions were a key factor influencing early food production on the southern Yangtze Delta. At least two episodes of inundation are recognized, the first occurring at c. 7200–5700 cal. yr BP and a second from c. 4700 cal. yr BP. The first involved increasing salinity of surface waters, likely associated with marine intrusion linked to post-glacial sea-level change (meltwater pulse (MWP) 2). The second appears to have been freshwater in nature and driven at least in part by extreme meteorological events of high levels of precipitation in combination with impeded drainage. These two episodes had profound impacts on Neolithic settlement and farming. Further hydrological changes, presumably linked to changes in sedimentary regime, geomorphology and drainage of the Taihu depression, recorded at the Chuodun site after c. 3000 cal. yr BP, appear to have had a major effect on technologically relatively advanced food production systems. While environmental pressures appear to have played an important role in shaping human activities and settlement on the southern Yangtze Delta, people responded by adopting strategies that included an increased reliance on food production, migration to more clement locations and implementation of new technologies, which possibly included the construction of flood defence works. [ABSTRACT FROM AUTHOR]

Abstract: This study presents two new, well-dated sedimentary pollen and charcoal records from high-altitude crater sites in the Virunga volcanoes, located in the Albertine Rift, central Africa, currently part of one of the world''s most biodiverse areas. Here we argue that Holocene vegetation changes in a ca 8000-year palaeoenvironmental record from a crater swamp at an altitude of 3474 m and a ca 2800-year record from a crater lake at an altitude of 4127 m are linked to variations in both climate and human activity. Climatic changes during the mid- to late Holocene are reflected in the high-altitude sites and more widely in adjacent parts of the Albertine Rift. Vegetation changes, comprising a decline in Ericaceous vegetation at ca 5000 cal yrs BP and subsequent expansion of Afroalpine vegetation, together with a later increase in taxa associated with lower montane forest (particularly Podocarpus), reflect increasing aridity during the mid- to late Holocene. Human-induced environmental change in the Virunga volcanoes is apparent only within the last millennium, despite the long history of human occupation of the area. Both study sites record significant forest clearance at ca 900 cal yrs BP, involving a reduction in lower montane forest taxa and increases in disturbance indicators. Changes in the composition of upper montane forest, and particularly the expansion of Hagenia, are possibly linked to anthropogenic-induced changes in the fire regime, and are apparent from ca 900 cal yrs BP. Human-induced environmental modification from the early part of the last millennium, likely associated with onset of the Late Iron Age, appears to have extended to high altitudes. The importance of natural, long-term climate change as a major cause of environmental change in the Albertine Rift has been eclipsed within the last millennium by human-induced environmental effects. [Copyright &y& Elsevier]

During the long history of human occupation in Australia and New Guinea, any interaction between people and their environment has been played out against changing sociocultural and environmental contexts. Although archaeologists have used palaeoenvironmental data to better characterize the relationships between humans and their environment, and palaeoecologists and geomorphologists have likewise used archaeological and historical information to augment their interpretations, it is our contention that few Australian and New Guinean studies have truly integrated these perspectives. Often archaeologists and palaeoenvironmentalists use each other's information in a one-dimensional manner, tendencies that have yielded simplistic interpretations of the past that overemphasize intentional or unintentional human causation on the one hand, and climatic and environmental causation on the other. We discuss three issues relevant to a more integrated understanding of the past: conceptualizing human-environment interactions, issues of scale and perspective, and multidisciplinary research integration in Australia and New Guinea. [ABSTRACT FROM AUTHOR]

Burning has been a near-continuous feature of the Australian environment but has become progressively more important since the mid-Tertiary, associated with the development of the characteristic sclerophyll vegetation. In the Quaternary, the extent of burning has varied temporally and regionally with glacial-interglacial cyclicity. Burning during glacial periods was reduced in drier areas, presumably because of a critical reduction in fuel availability, but increased in relatively wetter areas where fuel levels were high. On both glacial and Holocene timescales, peaks in charcoal often accompany transitions between fire-insensitive vegetation types, suggesting that burning is facilitated during periods of climate change and environmental instability. This suggestion has been supported by the demonstration of close relationships between fire and El Niño activity. Burning has also increased progressively over the past few hundred thousand years with major accelerations around the time of first human settlement of the continent and with the arrival of Europeans. To provide a firmer base for application of paleofire records to environmental management, there is an urgent need for a spatially more-substantial coverage of high-resolution fire records with good chronological control. [ABSTRACT FROM AUTHOR]

The local fire history of a coastal swamp catchment in New South Wales was reconstructed using two proxy records of fire: sedimentary macroscopic charcoal and fire-scar analyses of Xanthorrhoea johnsonii. The charcoal analysis provided a record of fire activity spanning the last 2800 years, while the Xanthorrhoea record covered the last approx. 300 years. The ability of each method to accurately record fire events was verified by cross referencing against the recent (post 1968) historic fire record. Fire history was then extrapolated beyond the historic record, to reveal an unprecedented level of fire activity in the last 35 years, which coincides with increased human activity in the area. In the prehistoric period charcoal and fire scars are comparatively rare, which is most parsimoniously ascribed to little fire activity, but perhaps represents skilful fire manipulation, as is often attributed to Aboriginal people. The comparatively minor fluctuations in macroscopic charcoal during the prehistoric period were approximately coeval with previous evidence of late Holocene environmental change in south-eastern Australia, suggesting that fire frequency at the site responded to climatic variability. The longer temporal perspective of this palaeoenvironmental approach provides information for the contemporary management of fire in this conservation reserve. [ABSTRACT FROM AUTHOR]

This research reports on a synthesis of radiocarbon (14C) dates and the organic content from a variety of depositional sites in a relatively small region in humid eastern Australia centred on Sydney. We focused on basal dates, changes in accumulation rates and the organic content of these sediment records in the period post-dating 21 thousand years ago to make inferences about past environmental conditions, or to infer the timing of past environmental change. We found that low rates of sediment and organic accumulation at the Last Glacial Maximum continued well into the late Pleistocene. The average rate of sediment deposition and organic content increased from about 14.5 calibrated kiloanni before present (cal ka BP), perhaps coincident with Meltwater Pulse 1A, but this was then checked by dry conditions during the Antarctic Climatic Reversal chronozone. An abrupt increase in the average rate of sediment accumulation coincided with the Pleistocene-Holocene boundary (at 11.7 cal ka BP), and this continued until about 9.2 cal ka BP, largely coinciding with the Antarctic thermal maximum, and probably reflecting reduced moisture availability in the Sydney region. Indication of depressed temperature and a more positive moisture availability, from about 9 to 7.6 cal ka BP, witnessed the fastest increase in the number of sites than at any other time. An overall drier early Holocene abruptly altered at about 7.5 cal ka BP and a mid-Holocene 'optimum' in moisture availability extended to 6.2 cal ka BP. The compilation of organic contents of the mid-late Holocene suggests environmental variability, but El Niño frequency or strength is not implicated as a driving force. Increased organic productivity, especially after 2.8 cal ka BP, corresponded to a peak in summer insolation, and associated seasonality of insolation and this is likely to have resulted in increased, or more consistent, summer rainfall and easterly air flow into the Sydney region. In contrast to previous generalisations about changes in south-eastern Australia during the Holocene, which have often relied on palaeoenvironmental records from further south, the southward migration of the intertropical convergence zone during the Holocene had vastly different synoptic outcomes in the Sydney region, with the early Holocene drier as continental air dominated, and the late Holocene wetter, as the synoptic conditions saw more tropical and easterly airflow. This work demonstrates the danger in making generalisations across regions and highlights the utility of the compilation of data at a homoclimatic, regional scale. • New syntheses of sediment accumulation and organic content from sites centred on the Sydney Basin in eastern Australia. • Challenging conditions continued well after the LGM, and this included a dry Antarctic Climatic Reversal. • The region was drier in the early and wetter in the late Holocene, reflecting the interplay between moisture sources. • The drier early Holocene abruptly ended at ∼7.5 cal ka BP and enhanced moisture availability then extended to 6.2 cal ka BP. • In the late Holocene insolation likely drove increased summer rainfall and easterly air flow into the Sydney region. [ABSTRACT FROM AUTHOR]