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Long tree-ring chronologies have been constructed in the Northern Hemisphere for dendroclimatology and palaeoenvironmental studies, radiocarbon calibration and archaeological dating. Numerous tree-ring chronologies have also been built in the Southern Hemisphere, primarily for dendroclimatology, but multimillennial chronologies are rare. Development of long chronologies from the Southern Hemisphere is therefore important to provide a long-term perspective on environmental change at local, regional and global scales. This paper describes the extension of the New Zealand Agathis australis (kauri) chronology from AD 911 to 1724 BC. Subfossil (swamp) kauri was collected from 17 swamp sites in the upper North Island. Kauri timbers were also obtained from an early twentieth century house on the University of Auckland campus. Twelve site chronologies and 11 independent tree-sequences were constructed and crossmatched to produce a 3631-yr record, which was calendar dated to 1724 BC–AD 1907 against the modern kauri master chronology. A new long chronology, AGAUc04a, was built by combining the modern kauri data with house timbers and subfossil kauri. This new chronology spans 1724 BC–AD 1998. It is of similar length to chronologies from Tasmania and South America and is the longest tree-ring chronology yet built in New Zealand. The greatest significance of the long kauri chronology lies in its potential as a high–quality palaeoclimate proxy, especially with regard to investigation of the El Niño–Southern Oscillation phenomenon. The chronology also has application to investigation of extreme environmental events, dendroecology, archaeology and radiocarbon calibration. [ABSTRACT FROM AUTHOR]

Precise timing of natural and cultural events provides a foundation for understanding how past natural phenomena have driven changes in population and culture. In this study, we used high-resolution Bayesian chronology to describe an event sequence of a massive and abrupt water level decline of a large lake and the contemporaneous cultural changes that occurred in eastern Fennoscandia during the mid-Holocene. The study provides the first transdisciplinary analysis of the causes and effects of the events by using a combination of archaeological, geological and ecological data. Nearly 6000 years ago, ancient Lake Saimaa, estimated to cover nearly 9000 km2at the time, was abruptly discharged through a new outlet. The event created thousands of square kilometres of new residual wetlands. The archaeological record shows a profound cultural replacement and a subsequent sharp human population maximum in the area during the decades after the decline in water level. During the population maximum, the proportion of Alces alces (moose) in the diet rapidly increased and became prominent as a dietary resource. The eventual population decline in the area coincided with ecological development towards old boreal conifer forests, along with the colonization of a new species of tree Picea abies (Norway spruce). The new ecosystem was less suitable for moose to forage in, and this attenuated the dietary role of moose and thus contributed towards the eventual population and cultural decline. The methodological approach described in this paper allowed the reconstruction of past natural and cultural events and demonstrated how they can be causally intertwined. [ABSTRACT FROM PUBLISHER]

An important feature of the ongoing debate about the acceptance of the Anthropocene as a formal chronostratigraphic unit with the same rank as the Holocene (epoch) has been either the existence or the lack of a Global Stratotype Section and Point (GSSP). In addition, the utility of the Anthropocene as a stratigraphic unit has also been questioned. In this paper, it is proposed that the discovery of the GSSP may not be a major problem and could only be a matter of time. However, the term Anthropocene itself, defined on the basis of the stratigraphic expression of human activities (e.g. large-scale agriculture and land clearance, accelerated release of greenhouse gases to the atmosphere) may significantly impact the current stratigraphic framework guided by the International Commission on Stratigraphy (ICS). Indeed, the formal usage of this term can not only lead to stratigraphic and terminological inconsistencies but can also influence the future development of the established chronostratigraphic scheme. These points should be considered by the ICS Anthropocene Working Group before making a final decision. The stratigraphic status of the Anthropocene, however, is a formal issue that should not affect current and future research on human-induced environmental and sedimentary changes, including their stratigraphic imprint. The message is twofold: leave the formal chronostratigraphic aspects to the ICS, and keep producing and organizing knowledge independently of the formal debate. Doing so would require the development of a parallel and likely transitory chronological system without formal stratigraphic value, from which the term Anthropocene would be, at least temporarily, excluded. [ABSTRACT FROM AUTHOR]

Landscape dynamics in the periglacial belt of a high mountain Mediterranean environment is a process of rapid evolution but complex reconstruction. Following this purpose, in this paper we discuss data from two sources concerning the past evolution of the present-day periglacial environment in the Sierra Nevada (southern Iberian Peninsula): mountain lake sediments and documentary sources. La Mosca lake sedimentary record provides information about the palaeocological evolution in the Mulhacén cirque over the last three millennia, while documentary sources enable us to reconstruct the landscape evolution in the high lands of this massif over the last eight centuries. During the late Holocene cold and wet phases have favoured the activity of geomorphic processes, with ephemeral development of glaciers in the highest northern cirques, abundance of late-lying snow patches and a decrease of the vegetation cover in the highest catchments. By contrast, warm periods have been more conducive to geomorphic stability, with an extension of the vegetation grass cover, but without glaciers and with a lower density of snow patches in summer. The comparison of the palaeocological evolution and associated palaeoclimatic conditions in the Sierra Nevada with other regional proxies shows evidence of the moderate sensitivity of the geomorphological processes occurring in the massif during the late Holocene with respect to the climate variability prevailing in the Iberian Peninsula and neighbouring areas. According to lake sedimentary records, the ‘Little Ice Age’ has been the coldest period during the late Holocene. Historical sources suggest a temperature increase of 0.93°C since the middle of the 19th century. [ABSTRACT FROM AUTHOR]

The paper analyzes the archaeobotanical and archaeozoological remains originating from the middle Holocene (i.e. Chalcolithic site of Poduri-Dealul Ghindaru, in Eastern Romania, Bacău County). Poduri-Dealul Ghindaru site is the only tell settlement known in the area of existence of the Cucuteni culture, with inhabitation levels from Neolithic to the Bronze Age. In order to better understand the diet components of the prehistoric inhabitation belonging to the Cucuteni A and Cucuteni B phases, we follow evidence from archaeozoology, carpology, and palynology. For the carpological taxa, we calculate their ubiquity, diversity, and edibility score. The two sets of taxa are then compared in their similarity. Palynological data record the presence of cereal grains in all samples. We present the archaeozoological taxa with their quantification values and we calculate for the Cucuteni A and B phases, and in comparison with the Bronze Age sample, their richness, Shannon–Weaver diversity index and equitability. A correspondence analysis is carried out in order to compare the exploitation strategies for the three assemblages. For the archaeobotanical data, we find that the Cucuteni A phase is dominated by anthropogenic activity indicators and a heavy reliance on cereals. The Cucuteni B phase seems to be characterized by a restriction of human activity. The archaeozoological data highlight a preference for large mammals (cattle, dear, boar) during Cucuteni A and BA and smaller mammals during Cucuteni B (sheep/goat, pig, hare). We conclude that although the subsistence strategies remain similar, the dietary components change during the Cucuteni A and B phases, probably in response to environmental changes. [ABSTRACT FROM AUTHOR]

This paper describes a tool for long-term global change studies; it is an update of the History Database of the Global Environment (HYDE) with estimates of some of the underlying demographic driving factors of global change. We estimate total and urban/rural population numbers, densities and fractions (including built-up area) for the Holocene, roughly the period 10 000 BC to AD 2000 with a spatial resolution of 5 min longitude/latitude. With a total global population increase from 2 to 6145 million people over that time span, resulting in a global population density increase of < 0.1 cap/km² to almost 46 cap/km² and a urban built-up area evolving from almost zero to 0.5 million km² (still only <0.5% of the total global land surface, but with a huge impact in terms of demands of food, services, building materials, etc.), it is clear that this must have had, and will continue to have, a profound influence on the Earth's environment and its associated (climate) change. We hope that this data base can contribute to the Earth System Modelers community to gain better insight into long-term global change research. [ABSTRACT FROM AUTHOR]

The lower Yangtze, eastern China, was colonized by several Neolithic and Bronze Age cultures giving rise to possibly the highest concentration of prehistoric sites in the world. Early Neolithic cultures in the delta region cultivated rice (Oryza sativa) and agricultural developments appear to have occurred throughout the Neolithic with abrupt socio-economic changes possibly associated with the terminal Neolithic. Given the extensive history of environmental exploitation and well-preserved archaeological sites, the Yangtze delta is an ideal setting to explore the complex interactions between humans and their environment. Multiproxies of environmental changes, namely pollen, charcoal and phytoliths, in a 14C AMS-dated sequence of sediments from an exposed profile at Qingpu, Yangtze delta, were investigated. 14C AMS dating indicates that the age range of the sedimentary sequence analysed is from c. 1800 to 6000 BP, and therefore encompasses the terminal Neolithic and subsequent Bronze Age in the region. This paper reviews this sediment-based evidence in the light of current understanding of human-environment interactions during a critical phase of the development of the Yangtze delta and associated human cultures. [ABSTRACT FROM AUTHOR]

This paper reviews recently published literature, most of which was published in Chinese, and searches for regional patterns of Holocene changes useful in depicting global patterns. The Holocene in the Xinjiang region can be divided into three stages: a warming and dry early stage (from 11 ∼ 10 to 8 ∼ 7 ka BP), a warm and wet middle stage (from 8 ∼ 7 to 4.5 ∼ 3 ka BP) and a fluctuating cool and dry late stage (since 4.5 ∼ 3 ka BP). The Holocene in the northern Tibetan Plateau can also be divided into three stages: a warming and wet stage (from 10.5 ∼ 10 to 5 ∼ 4 ka BP), followed by a variable drying and probably warm stage (5 ∼ 4 to 3 ka BP) and ending with a cool and dry stage (since 3 ka BP). In the Inner Mongolian Plateau, the early Holocene (from 10.5 ∼ 9.5 to 8 ∼ 7.5 ka BP) was warming and dry, and a warm and wet climate occurred from 7.5 to 3.5, during which the best time was 6.3–3.8 ka BP; the climate has been variably drying and probably cooling since 3.5 ka BP. In the northwestern part of the Loess Plateau, several Holocene palaeosols have been identified (10–9, 7.5–5, 4–3 and 2.7–2 ka BP) with the 7.5–5 ka BP palaeosol being most strongly expressed. The best-developed palaeosol-equivalent in major valleys is a swamp-wetland facies deposited between 8885 and 3805 14C yr BP under an extremely wet regime. The climate has fluctuated significantly at least three times around a dry and probably cool regime after the swamp-wetland facies-depositional period. Our summary shows that the Holocene Climatic Optimum occurred nearly contemporaneously (8–5 ka BP) at all sites in the Xinjiang region, in the Inner Mongolian Plateau and in the northwestern part of the Loess Plateau. A warming and wet early Holocene (10–8 ka BP) in the northern Tibetan Plateau is most likely related to high effective soil moisture resulting from snow and ice melting. We propose here that the middle Holocene Climatic Optimum (8–5 ka BP) in arid to semi-arid China was primarily a delayed response of the low latitude oceans to high latitude peak insolation (9–8 ka BP). [ABSTRACT FROM AUTHOR]

Despite their huge extent, the peatlands of Russia are an under-exploited source of data on palaeoenvironmental change. We investigated the Holocene history of Staroselsky Moch, an ombrotrophic peatland in the Tver Region of European Russia by analysis of testate amoebae, peat physical properties, plant macrofossils and pollen. The peatland developed through a classic hydroseral succession in the early Holocene with a sharp decline in mineral input to 6200 cal. BC followed by an abrupt transition from fen to bog vegetation around 5500 cal. BC. Through the Holocene, the peatland has accumulated carbon at a mean apparent rate of 21.5 g C m−2 yr−1 suggesting that carbon accumulation rates in peatlands of European Russia lie close to the global average, and contrasting with a short sequence of eddy-covariance data which implies a net loss of carbon. The testate amoeba record shows considerable variability which may be driven by climate, but changes are not well replicated in the macrofossil or pollen data. We tentatively infer (1) a phase of early Holocene warming commencing around 7200 cal. BC, (2) dry peatland surface conditions c. 3700–3900 cal. BC, (3) a shift to wetter conditions from c. 3900 cal. BC, and (4) drier conditions from c. 400 cal. BC onwards. More robust and precise hydroclimatic reconstructions for this region will require the development of a regional transfer function and the replication of results between cores and sites. [ABSTRACT FROM AUTHOR]

Central Chile is heavily exploited for mineral and water resources, with agriculture and large urban populations all creating intensive landscape use. Few records of past environmental and climate change are available that afford a broader context. To aid in this assessment, we present a 700-year reconstruction from Laguna del Maule (LdM) in the high Andes of central Chile based on sedimentological, geochemical, diatom and pollen analyses. The age model is based on 210Pb/137Cs and 14C dating tied into known volcanic eruptions. Sedimentology consists of organic-rich sediments and diatom oozes with several interspersed volcanic-rich facies and two tephra deposits. Sediment geochemistry exhibits increased productivity (high Br/Ti, biosilica) and more dominant oxic conditions (high Fe/Mn) from AD 1300 to 1400 and from AD 1650 to 1850, likely during periods of relatively lower lake levels and better development of littoral environments. However, during this later period, high elevation vegetation was dominant, indicative of regional cooler/wetter conditions. In contrast, sediments deposited from AD 1850 to 1930 evidence decreased productivity and increased anoxic lake bottom conditions. The ‘Little Ice Age’ (LIA) in LdM is characterized by significant variations in lake dynamics and hydrology with cooler/wetter conditions (AD 1570–1700), major environmental changes in the 18th century and ending at ca. AD 1850. LdM record documents the impact of the LIA in the southern hemisphere and stresses the global nature of this climate period. Large changes in lake dynamics and diatoms assemblages during the 20th century could be related to anthropogenic impacts, but recent changes in climate patterns cannot be excluded. [ABSTRACT FROM AUTHOR]

Apparent changes in vegetation distribution, fire, and other disturbance regimes throughout western North America have prompted investigations of the relative importance of human activities and climate change as potential causal mechanisms. Assessing the effects of Euro-American settlement is difficult because climate changes occur on multi-decadal to centennial time scales and require longer time perspectives than historic observations can provide. Here, we report vegetation and environmental changes over the past ~13,000 years as recorded in a sediment record from Bison Lake, a subalpine lake on a high plateau in northwestern Colorado. Results are based on multiple independent proxies, which include pollen, charcoal, and elemental geochemistry, and are compared with previously reported interpretations of hydroclimatic changes from oxygen isotope ratios. The pollen data indicate a slowly changing vegetation sequence from sagebrush steppe during the late glacial to coniferous forest through the late Holocene. The most dramatic vegetation changes of the Holocene occurred during the ‘Medieval Climate Anomaly’ (MCA) and ‘Little Ice Age’ (LIA) with rapid replacement of conifer forest by grassland followed by an equally rapid return to conifer forest. Late Holocene vegetation responses are mirrored by changes in fire, lake biological productivity, and watershed erosion. These combined records indicate that subsequent disturbance related to Euro-American settlement, although perhaps significant, had acted upon a landscape that was already responding to MCA-LIA hydroclimatic change. Results document both rapid and long-term subalpine grassland ecosystem dynamics driven by agents of change that can be anticipated in the future and simulated by ecosystem models. [ABSTRACT FROM AUTHOR]

Three parallel overlapping cores have been taken in the Albanian side of Lake Shkodra (Albania/Montenegro). The chronological frame of the record, spanning approximately the last 4500 years, has been assessed using four radiocarbon dates and four well-known tephra layers of Italian volcanoes. Multidisciplinary analyses turned out to be decisive to understand environmental, climatic changes and human impact. Here, we focus on palynology. The humidity at Shkodra was always enough to allow the developing of a luxuriant arboreal vegetation. The pollen percentage diagram does not record important changes in terrestrial plants percentages. Arboreal pollen (AP) shows only a rather slight decrease, with ‘natural forests’ replaced by intensive cultivation of chestnut and walnut in the last seven/eight centuries. The rather minimal changes in composition and dominance are because of the fact that the pollen rain comes from different vegetation belts, from the Mediterranean to the alpine one. Two major periods of humidity are found, one at the base of the pollen concentration and influx diagram, before 4100 yr BP, the other at 1300 yr BP. Minima in pollen influx and concentration occurred soon before 4000, at ca. 2900 and at ca. 1450 yr BP These minima, interpreted as aridity crises, show a temporal coincidence with the so-called Bond events 1-3 already found in other central and eastern Mediterranean records. The minimum in AP occurring after 500 yr BP could represent the record of the ‘Little Ice Age’, even if it could be the effect of a strong land use. [ABSTRACT FROM PUBLISHER]

It is increasingly apparent that sea-level data (e.g. microfossil transfer functions, dated coral microatolls and direct observations from satellite and tidal gauges) vary temporally and spatially at regional to local scales, thus limiting our ability to model future sea-level rise for many regions. Understanding sea-level response at ‘far-field’ locations at regional scales is fundamental for formulating more relevant sea-level rise susceptibility models within these regions under future global change projections. Fossil corals and reefs in particular are valuable tools for reconstructing past sea levels and possible environmental phase shifts beyond the temporal constraints of instrumental records. This study used abundant surface geochronological data based on in situ subfossil corals and precise elevation surveys to determine previous sea level in Moreton Bay, eastern Australia, a far-field site. A total of 64 U-Th dates show that relative sea level was at least 1.1 m above modern lowest astronomical tide (LAT) from at least ~6600 cal. yr BP. Furthermore, a rapid synchronous demise in coral reef growth occurred in Moreton Bay ~5800 cal. yr BP, coinciding with reported reef hiatus periods in other areas around the Indo-Pacific region. Evaluating past reef growth patterns and phases allows for a better interpretation of anthropogenic forcing versus natural environmental/climatic cycles that effect reef formation and demise at all scales and may allow better prediction of reef response to future global change. [ABSTRACT FROM AUTHOR]

California mussels (Mytilus californianus) excavated from archaeological site CA-SRI-147 on the southern side of Santa Rosa Island, California, provided a discontinuous environmental record spanning about 7000 years. An earlier report of the midden remains at this site found a weak inverse correlation between changes in mussel shell length and sea surface temperature (SST), but not productivity, and a decline in mussel size from ~5800 to 5100 calendar years before present during a period of low productivity and increasing SST. This study uses oxygen isotopes from the site to directly compare environmental change to shifts in faunal assemblage. Four intervals of low temperatures are revealed in the nearshore environmental data, each corresponding to a significant change in faunal assemblage at the site. The first occurs c. 6600 calendar years before present (cal. BP) and coincides with the greatest amount of mussel shell mass and size in the site. The second (c. 5500 cal. BP) occurs during an interval of variable mussel contribution and increasing red abalone (Haliotis rufescens) contribution. The third (c. 4800 cal. BP) occurs during a time when platform mussels (Septifer bifurcatus) exceed California mussels in meat weight, while the final interval (c. 3700 cal. BP) occurs prior to a period of probable site hiatus. The overall pattern of decreasing shell contribution and size at the site is not found in the mollusk isotope data, suggesting that environmental change had a profound impact on short-term variability, while human predation of key resources provided the long-term primary stress on nearshore biota. [ABSTRACT FROM AUTHOR]

High resolution records of sediment accumulation are necessary to evaluate subtle temporal and spatial variations in sediment flux, especially in the context of decadal-scale human–environment interactions. Digital photography using consumer-grade cameras may be used to gather thousands of stratigraphic measurements to ± 1 mm (potentially equivalent to ± 2 years of accumulation) and provide data amenable to statistical manipulation. This new approach is illustrated with an evaluation of 15th century landscape change in Iceland. High resolution measurements show that apparent ‘spikes’ in accumulation after episodes of plague are an artefact of lower resolution measurements (± 2.5 mm) over decadal periods. Regional records show little change in sediment accumulation rates after the plagues but key local records made possible using this new methodology reveal that the period ad 1389–1416 (encompassing the plague outbreak of ad 1402) had some of the lowest sediment accumulation rates since settlement of the island. This new approach to landscape assessment indicates that in this pastoralist community the aftermath of human mortality rates of 50–60% saw no development of feral sheep populations or a switch to less labour-intensive wool production. The implication is that cattle production was maintained and the relative easing of landscape impacts could explain the lag between 14th century climatic deterioration and 18th century increases in landscape change. [ABSTRACT FROM AUTHOR]

A radiocarbon-dated multiproxy palaeoenvironmental record from the Lower Thames Valley at Hornchurch Marshes has provided a reconstruction of the timing and nature of vegetation succession against a background of Holocene climate change, relative sea level movement and human activities. The investigation recorded widespread peat formation between c. 6300 and 3900 cal. yr BP (marine ‘regression’), succeeded by evidence for marine incursion. The multiproxy analyses of these sediments, comprising pollen, Coleoptera, diatoms, and plant and wood macrofossils, have indicated significant changes in both the wetland and dryland environment, including the establishment of Alnus (Alder) carr woodland, and the decline of both Ulmus (Elm; c. 5740 cal. yr BP) and Tilia (Lime; c. 5600 cal. yr BP, and 4160–3710 cal. yr BP). The beetle faunas from the peat also suggest a thermal climate similar to that of the present day. At c. 4900 cal. yr BP, Taxus (L.; Yew) woodland colonised the peatland forming a plant community that has no known modern analogue in the UK. The precise reason, or reasons, for this event remain unclear, although changes in peatland hydrology seem most likely. The growth of Taxus on peatland not only has considerable importance for our knowledge of the vegetation history of southeast England, and NW Europe generally, but also has wider implications for the interpretation of Holocene palaeobotanical records. At c. 3900 cal. yr BP, Taxus declined on the peatland surface during a period of major hydrological change (marine incursion), an event also strongly associated with the decline of dryland woodland taxa, including Tilia and Quercus, and the appearance of anthropogenic indicators. [ABSTRACT FROM PUBLISHER]

During the Holocene, Florida experienced major changes in precipitation and runoff. To better understand these processes, shallow marine sediment cores from Charlotte Harbor (southwest Florida) were studied, covering approximately the past 9000 years. Whole core XRF scanning was applied to correlate different sediment cores on a river to sea transect. Biomarkers were used to identify periods with increased runoff and primary productivity. The mid-Holocene sediments are characterized by a relatively large input of terrestrially derived organic matter, with a maximum in precipitation and runoff around 5 kyr BP. This maximum can be linked to large-scale changes in the hydrological cycle involving shifts of the ITCZ, Bermuda-Azores High and Polar Front. Around 3.5 kyr BP, Charlotte Harbor changed from a runoff-dominated environment to a more oligotrophic and marine setting. Although other studies suggest that, around this time, precipitation in Florida increased, this is not reflected by the Charlotte Harbor records. Possibly, wetter conditions in Florida due to gradual, ongoing, sea level rise in combination with increased precipitation, resulted in accumulation of organic matter on land. Increased sedimentation rates, terrestrial input and primary productivity observed in the upper part of the record are likely a consequence of human impact during the past century. Throughout the record, indications for storm activity can be recognized as coarser grained layers consisting of quartz sands or shell debris. These layers are rare during the mid Holocene, but between 3.2 and 2 kyr BP, their numbers increase, suggesting an increase in tropical cyclone activity in the Gulf of Mexico. [ABSTRACT FROM AUTHOR]

The Seille Valley in eastern France was home to one of Europe’s largest Iron Age salt industries. Sedimentology, palynology and geochronology have been integrated within ongoing archaeological investigations to reconstruct the Holocene palaeoenvironmental history of the Seille Valley and to elucidate the human–environment relationship of salt production. A sedimentary model of the valley has been constructed from a borehole survey of the floodplain and pollen analyses have been undertaken to reconstruct the vegetation history. Alluvial records have been successfully dated using optically stimulated luminescence and radiocarbon techniques, thereby providing a robust chronological framework. The results have provided an insight into the development of favourable conditions for salt production and there is evidence in the sedimentary record to suggest that salt production may have taken place during the mid-to-late Bronze Age. The latter has yet to be identified in the archaeological record and targeted excavation is therefore underway to test this finding. The development of the Iron Age industry had a major impact on the hydrological regime of the valley and its sedimentological history, with evidence for accelerated alluviation arising from floodplain erosion at salt production sites and modification of the local fluvial regime due to briquetage accumulation on the floodplain. This research provides an important insight into the environmental implications of early industrial activities, in addition to advancing knowledge about the Holocene palaeoenvironmental and social history of this previously poorly studied region of France. [ABSTRACT FROM AUTHOR]

Prehistoric hunter-gatherer population size is often assumed to follow climatic and other environmental forcings that affect environmental productivity and the availability of food for human foragers. We tested this assumption by studying the co-variation of archaeological and palaeoenvironmental records during the Holocene in eastern Fennoscandia. The reconstruction of population history is based on the summed probability distribution of archaeological radiocarbon dates, and environmental changes are tracked with locally available, high-resolution biological and physical proxies that are relevant in terms of hunter-gatherer food availability and population dynamics. The results show major population growth during the period of high summer temperature and high productivity of the terrestrial, lacustrine and marine ecosystems that occurred during 7500–5700 cal. yr BP. The growth was followed by an abrupt decline during 5500–4000 cal. yr BP correlating with the onset of late-Holocene cooling and a major forest ecosystem change brought about by the expansion of Norway spruce and the associated change from species-rich mixed forests to a conifer-dominated boreal ecosystem. Forest ecosystem changes likely enforced the negative effects of decreasing productivity on hunter-gatherer food availability. The link between population and environmental proxies breaks down along with the intensification of agriculture after 3500 cal. yr BP, which indicates that agriculture weakened the environmental forcing on long-term human population dynamics. [ABSTRACT FROM AUTHOR]

The response of diatom assemblages to changes in climate and nutrients over a 1200 year timescale was investigated by means of a multiproxy sediment core study involving radiometric dating, diatoms, grain size, loss on ignition and geochemical analysis. Four stages of environmental change were defined, each being consistent with changes in documented human activity and known climate patterns. From ad 750 to 880 relatively high nutrient status and a cold, unstable climate was inferred based on the high abundance of Aulacoseira subarctica and high Na/K and Na/Al values. In the following 1000 years (ad 880–1880) diatom assemblages were dominated by Cyclotella comensis, Cyclotella radiosa and Achnanthidium minutissimum, suggesting a long period of relatively low productivity and, by implication, that climate was the main control on the community during this period. Two climatic phases, namely the ‘Medieval Warm Period’ (MWP) and the ‘Little Ice Age’ (LIA), were apparent. According to shifts in the diatom assemblages and other proxies, it was proposed that the MWP was initiated from ~ad 880 and was terminated by the LIA at ~ad 1350. After ad 1880 the palaeoecological data revealed a period of strong human impact in the catchment and hence higher productivity. This work illustrates the complexity of climate–nutrient interactions and the roles of the two drivers on different timescales and at various stages of the lake’s history: climate impacts were more pronounced when nutrient concentrations were relatively stable prior to ~ad 1880; while nutrients appeared to play a more important role in regulating diatom communities from the mid-eighteenth century. [ABSTRACT FROM PUBLISHER]

A high-resolution record of Holocene environmental and climatic change in the Balikun area was reconstructed from a sediment core from the Lake Balikun. Multiproxy data show that the climate was extremely arid during the early Holocene (before 8.6 cal. ka BP). Moisture began to increase after 8.6 cal. ka BP and the climate was humid between 7.9 and 4.3 cal. ka BP. A significant dry event occurred around 4.3–3.8 cal. ka BP. The climate became generally wet during the late Holocene (after 3.8 cal. ka BP). The Holocene pollen and geophysical records do not indicate a wet early Holocene, making it evident that there was no early-Holocene humid period associated with peak Asian monsoon strength. Regional comparisons indicate that this region has a different pattern of Holocene environmental and climatic change from the Asian monsoonal area and south Siberia. [ABSTRACT FROM AUTHOR]

The ancient kingdom of Loulan on China’s Silk Road has disappeared for about 1500 years. Historical records have documented widespread cultivation in Loulan which supported the kingdom’s prosperity for hundreds of years. However, no farmland ruins have been found although the ancient Loulan city was discovered more than 100 years ago. In this study, remotely sensed, geomorphic and geological observations of possible farmlands in Loulan were analyzed. A wide distribution of partly preserved plots with recognizable regular and straight boundaries, the existence of crossed canals, the occurrence of a gypseous incrustation layer (GIL) overlying on the surface of farmland-like blocks, and extracted large-sized pollen grains of cultivated grass from GIL samples provide new evidence for the ancient farmlands. Field observations revealed that the upper cultivated soil layer overlaid on GIL, i.e. soil horizon A, had been wind-eroded and GIL is the ruined soil horizon B. These new findings point to a well-developed agriculture of the ancient Loulan kingdom. The size and distribution of the farmlands and the thickness of the GIL suggests that irrigation for cultivation in this currently exceedingly arid area had lasted for a long time. Fluvial and lacustrine sediments in Loulan area deposited during the about 4 to ~ 8 ka BP period, revealing that the wet Holocene optimum and two arid events of about 4 and 8 ka BP occurred in the westerlies-dominated northwest China. The Loulan kingdom period was another wet stage when the ecological environment was the typical cultivated grass of oasis near wetland. The insufficiency of water during the late period of the Loulan kingdom led the decline of irrigation agriculture and finally the renunciation of the kingdom. [ABSTRACT FROM PUBLISHER]

The environmental evolution, inferred from the sedimentary sequence, that has occurred during the last three millennia in a drained coastal marsh in the Tiber delta is presented. The stratigraphy of the sediments has been revealed through excavation of 7 km of trenches in an area of about 1.5 km2. The most evident environmental variations are represented by the transformation of freshwater marshes into brackish-water marshes, around the ninth–eighth centuries bc, and from brackish-water to freshwater marshes during the fourteenth–fifteenth centuries ad. The change in the water salinity was produced by the opening and closure of an inlet connecting the marshes and the sea because of the evolution of the delta. Other environmental variations are reflected in the fluctuations in the water level of brackish marshes: in a general trend towards an increase in water level, probably caused by the late-Holocene sea level increase, some phases of water decrease in the range of 10–20 cm occurred. The majority of the environmental changes were largely produced by erosion and sedimentary events connected with Tiber delta variations induced both by human impact and climate. The lower water levels were contemporary with glacial advances in the Alps and the Apennine chains. At least one of the five decreases of the water level was contemporaneous with a marine regression documented in Italy. [ABSTRACT FROM AUTHOR]

In the Mediterranean there is often no clear time gap separating an early-Holocene period of nature-dominated environmental change from a human-dominated late-Holocene one. This mid-Holocene ‘mélange’ has been the subject of debates that have often been polarised between support for climatic causation and those favouring anthropogenic explanations for changes in vegetation, river flooding, wildfire regimes, etc. One way to shed light on the causes of mid-Holocene landscape changes is to focus on natural archives, such as lake and cave isotopes, the records of which can be unambiguously attributed to climatic forcing. These primary climate proxies can then be compared and contrasted with secondary or response variables, such as pollen and microcharcoal data, which can be the product of either climate changes or human activity or both, ideally using a multiproxy approach. In addition, synthesised primary palaeoclimate data can be compared with regional-scale climate modelling simulations. Both model output and proxy data suggest an east—west division in Mediterranean climate history. They indicate that the eastern Mediterranean experienced an increase in winter-season precipitation during the early Holocene, followed by an oscillatory decline after ~6 ka BP. In western parts of the Mediterranean, early-Holocene changes in precipitation were smaller in magnitude and less coherent spatially, and maximum increases occurred during the mid Holocene, around 6—3 ka BP, before declining to present-day values. Coincident with and partly stimulated by these climatic changes, complex societies developed across the Mediterranean, particularly in eastern parts of the basin during the Bronze Age. In consequence, by the mid-first millennium BC, human-induced land cover conversion, a drier and more variable climate, and changed fire regimes combined to establish typical sclerophyllous vegetation and landscapes in the circum-Mediterranean region. [ABSTRACT FROM AUTHOR]

The eastern Mediterranean region witnessed changes in human culture of the highest importance between ~9000 and ~2500 cal. BP (7000—500 BC) and over the same time period was affected by very significant shifts in climate. Stable isotope data from lake and deep-sea sediment cores and from cave speleothems show an overall trend from a wetter to a drier climate during the mid Holocene. Superimposed on this trend were multicentennial oscillations in climate, with notable arid phases occurring around 5300—5000 BP, 4500—3900 BP, and 3100—2800 BP (all ages are expressed in calibrated/ calendar years). These phases coincide with major archaeological transitions across the eastern Mediterranean region (Chalcolithic to early Bronze Age, EBA to MBA, and LBA to Iron Age) implying that environmental stress or opportunity may have acted as a pacemaker for cultural change and re-organisation. We use 14C and δ 13C analysis of archaeobotanical samples from two protohistoric sites in Syria to illustrate the linkage between water availability, climate and cultural change during the third and second millennia BC. Specific societal responses to environmental change were not predictable in advance, but resulted instead from contingent processes involving antecedent conditions, human choice and adaptive strategies. Pollen analysis highlights how changes in climate were coupled to increasing human impacts to transform the region’s landscapes. Initial human-induced land-cover transformation commonly took place during Bronze Age times, sometimes coinciding with phases of drier climate, although the pattern and precise timing varied between sites. Changes in climate between the early and late Holocene thus helped to transform eastern Mediterranean landscape ecologies and human cultures, but in complex, non-deterministic ways. [ABSTRACT FROM AUTHOR]

Lake sediment and geomorphic evidence from the Loch of the Lowes/St Mary's Loch basin in the central Southern Uplands of Scotland provide a multiproxy reconstruction of changing sediment availability and transmission through the catchment. Interrogation of magnetic, geochemical and grain size parameters for lake and catchment materials suggests it is possible to identify independent proxies that reflect both supply (availability) and discharge (capacity) controls on the sediment signal. Chronological control for the lake sediment record is proposed by linking a 210Pb/137Cs chronology for the last c. 120 yr to an age/depth profile based on proposed temporal correlations between cyclic HIRM/χLF variability and the North Atlantic Oscillation. Geochronological studies on debris cones and alluvial fans yield evidence for episodic hillslope gullying ∼2000-0 BC with more extensive region-wide slope instability AD 700-900, 1100-1300 and after AD 1450-1550 and gully stabilization over the last 150 years. The latter two episodes coincide with the lake sediment evidence for increased sediment supply from ∼AD 1600 declining after ∼AD 1870. The capacity-related lake proxies appear to identify phases of increased flooding ∼AD 1625-1650, 1680-1700, 1730-1760, 1800-1815, 1850-1880, 1910-1930, 1960-1970 and possibly the 1990s. Close correspondence between the sediment 'flood' archive and historical records of flooding in Scotland suggests that lake-catchment systems of this type have the potential to yield valuable information on past hydrological response. [ABSTRACT FROM AUTHOR]

The primary factors that control alluvial fan evolution still remain in question particularly for the Holocene. Holocene centennial- and millennial-scale climate fluctuations are relatively subtle and more frequent than those of glacial/interglacial transitions, therefore intrinsic factors such as rock type or basin size are hypothesized to moderate significantly the influence of Holocene climate and climate change on alluvial fan processes. Here, we examine variability in styles and rates of alluvial fan aggradation along a single mountain front that is characterized by basins of varying size and rock type (carbonate versus granite). Basin rock type is more closely correlated to variability in the episodic nature and magnitude of alluvial fan aggradation than is basin area. Bedrock physical and chemical weathering properties control sediment delivery to the piedmont and thus influence alluvial fan aggradation. We suggest that the particle size of grus produced by weathering of granitic rocks fosters sediment mobilization and alluvial fan aggradation during episodes of increased precipitation in the Holocene. Sediment mobilization during wetter climates is also possibly enhanced by drought-related fires and vegetation loss that occurred during preceding drier periods. In contrast, carbonate outcrops weather to both dissolved materials and clastic sediment and relatively rapid cementation of talus precludes its transportation out onto the piedmont under almost all Holocene climatic conditions. If the scale of past Holocene climate change is the closest analogy to current global change, this study documents some mechanisms by which different rock types can exert dramatically different effects on landscape response to those changes. [ABSTRACT FROM AUTHOR]

Geochemical analyses (x-ray fluorescence, δ13C and C/N ratios) were used to reconstruct early Holocene environments (between 10 685 and 7260 cal. yr BP) at a small lake near Holebudalen, southern Norway. Results show a period of increasing stability, with reduced catchment inwash (shown by titanium and potassium minerals), vegetation stabilization and increasing aquatic productivity (C/N ratios). However, periods of instability (loss on ignition (LOI) decrease) are also seen (most notably at c. 9060 cal. yr BP). Chironomid-inferred July temperature (CI-T) reconstructions show a cooling of c. 2°C (RMSEP = 1.0°C) between c. 8400 and 8000 cal. yr BP and so high-resolution (5 mm; c. 20 yr) diatom analyses were conducted between 8675 and 7830 cal. yr BP in order to further investigate this change. Between c. 8270 and 8000 cal. yr BP there were large reductions (> 50%) in the abundance of tychoplanktonic diatoms (eg, Aulacoseira species) and absolute increases in periphytic diatom communities (eg, Navicula pupula, Pinnularia mesolepta). The multiproxy analyses suggest a period of increased lake ice cover with associated reductions in turbulence during this time. Diatom flora changes are concomitant with a fall in percent LOI and increased catchment erosion at the site and other evidence of regional climatic perturbations in the early Holocene. Therefore, superimposed upon an early Holocene warming trend at Holebudalen, there are climatic perturbations, for example reflected between c. 8200 and 8000 cal. yr BP by diatom communities. [ABSTRACT FROM AUTHOR]

To reconstruct Lateglacial and Holocene environmental changes in the British uplands, two c. 5.8 m long sediment cores from Crummock Water (NW England), together with several hundred soil samples from the Crummock Water catchment, were studied using magnetic techniques. Optically stimulated luminescence (OSL) dating using fine silt quartz and 14C dating of terrestrial plant macrofossils were used to establish a chronology for the lake sediments. A good agreement between optical and 14C ages indicates first, that the OSL dating method can be used to date lake sediments in the British Isles; second that macrofossil-based 14C dating can be used to avoid the problem of 'old carbon' error associated with bulk sample 14C dating of lake sediments and third, that the established chronology is robust. The lake sediment magnetic properties indicate a series of changes in sediment composition during the Holocene, which correlate well with sediment lithology, water content and weight-loss-on-ignition. The first change corresponds to the Lateglacial/Postglacial climatic shift at around 11 400 years ago; the subsequent suite of changes corresponds to a probable regional onset of human activity at 2000 BC, and particularly to the intensification of human activity at around AD 900. A comparison of the lake sediment magnetic properties and those of the catchment soils shows a clear linkage for the Lateglacial period, and for the period after AD 900. In contrast, detailed magnetic measurements of the early- through mid-Holocene sediments suggest that their magnetic properties are dominated by bacterial magnetosomes. [ABSTRACT FROM AUTHOR]

What was the environmental setting for changes in the settlement pattern of Adaïma, a mid-fourth to early-third millennium site in the Egyptian Nile valley? Analysis of charcoal collected from the archaeological soil was performed on contexts from several periods. The settlement was set up in an environment where the vegetation was probably more extended, with more wooded desert margins. Over 600 years, changes in the charcoal spectrum reflect a possible local desertification and the impact of human activities on the vegetation of the floodplain, perceptible in particular through the development of ruderal Calotropis procera. [ABSTRACT FROM AUTHOR]

Rice (Oryza sp.) agriculture sustains vast numbers of people and, despite great advancements made in recent years, questions about its origins and spread throughout Asia remain unanswered. This study uses sedimentary biomarker, stable carbon isotope and palynological analyses to investigate early rice agriculture in the Yangtze delta, a region where rice agriculture emerged at least 7000 years ago. Accelerator mass spectrometer (AMS) 14C dating reveals the age of sedimentary section to be between c. 6000 and 1800 cal. BP. Widespread clearing of forest vegetation c. 2400 cal. BP, is the earliest major human influence detected in the Qingpu record. Following this, rice agriculture probably dominated the Qingpu area. Evidence supporting rice agriculture after c. 2400 cal. BP is provided by increased Poaceae and Cereal-type taxa, which occur with high concentrations of plant wax n-alkanes with a dominant C3 plant origin (C27–C31 with odd/even preference, δ13C -29.8‰ to -36.3‰). Also, high concentrations of a C20 highly branched isoprenoid (HBI) thought to be from epiphytic algae associated with rice agriculture occur after c. 2400 cal. BP. 13C-depleted diploptene (in high concentrations) and 13C-depleted C31 3b-methylhopanes of methanotrophic bacterial origin also occur after c. 2400 cal. BP. The strong methane cycle detected in the trench sediment may have provided an alternative CO2 source for plants and algae associated with rice agriculture. [ABSTRACT FROM AUTHOR]

Past aeolian activity was reconstructed at four dunefields in the prairie parkland and boreal forest of central Saskatchewan to elucidate landscape response to environmental change. Optical ages from stabilized dunes in the boreal transition ecoregion indicate two episodes of activity. The first, at about 11 ka, corresponds to a period of early-Holocene parkland and grassland cover following deglaciation and drainage after about 13.0 ka, and brief establishment of boreal forest. The second, between about 7.5 and 5 ka, corresponds to a period of mid-Holocene parkland–grassland cover. Optical ages from dunefields in the prairie parkland primarily record mid-Holocene activity, between about 7.5 and 4.7 ka, corresponding to a period of grassland cover, with some reworking continuing into the late Holocene. Although this area was deglaciated by about 13.5 ka, there is no evidence of early-Holocene dune activity, suggesting that mid-Holocene activity may have reworked earlier deposits here. Consequently, much of the morphology and stratigraphy observed in these dunefields are associated with mid-Holocene activity, likely associated with increased aridity and reduced vegetation cover at that time. This study provides the most northerly evidence of mid-Holocene dune reactivation on the Great Plains, lending support to the assertion that aeolian activity was widespread at that time. [ABSTRACT FROM AUTHOR]

Alluvial valley fills from tributaries to the upper Republican River, southwest Nebraska, USA, provide soil- and morpho-stratigraphic evidence for an episode of channel incision that occurred between c. 1100 and 800 14C yr BP, based on 11 new radiocarbon ages. This local episode of channel incision correlates with other alluvial stratigraphic studies from the central Great Plains and demonstrates regionally synchronous fluvial behaviour. Proxy records of palaeohydrologic conditions in and around the Great Plains (including lacustrine, aeolian and geomorphological sources) indicate that channel incision correlates with a multicentennial episode of common, widespread drought. Temporally, this drought episode corresponds to the period recognized in many regions as the Mediaeval Warm Period (MWP). Therefore, this research demonstrates: (1) a relationship in the semi-arid central Great Plains between drought and increased fluvial incision; and (2) a local/regional geomorphic response to a particular episode of global climate change. [ABSTRACT FROM AUTHOR]

Palynological investigations were carried out in the coastal lowland of northwestern Crete, in the area of Lake Kournas. Results comprise the longest continuous vegetation record (9000 radiocarbon years) for Crete. From about 8500 to 7500 BP, open deciduous-oak forest occurred and appears to reflect the driest conditions of the Holocene. After 7500 BP, tree-pollen numbers increase. Some of these tree species are thought to be autochthonous, but for at least six species this is doubted and the presence of their pollen is ascribed to long-distance transport. Up to 6000 BP, the local vegetation included deciduous and evergreen oaks, Pistacia, Phillyrea and a variety of herbs. Only after 7000 BP, some species, e.g., Mercurialis annua, Cynocrambe and spores of Pteridium, might indicate the effects of Neolithic habitation. Towards 6000 BP, plane tree and Styrax (storax) appear; from about 6000 BP, olive is present and human activity becomes more evident. Slowly, pollen types indicative of the exploitation of present-day Mediterranean vegetation, e.g., Poterium and Ericaceae, appear and the presence of the alga Gloeotrichia indicates a rise in phosphate. A striking aspect of the sediment core nearest to the sea is a pumice layer originating from the Theran (Santorini) eruption. From the manner of its deposition it is concluded that no tsunami met the Cretan beach. Influence of the eruption from Thera on the vegetation is hardly visible. Decrease of economically important cultivated plants, e.g., olive, already took place decades, up to about a century, before the volcanic eruption. Around the time of the eruption, the values of some pollen types hardly changed, others increased and another group decreased. This pollen behaviour appears to be explained rather by socio-economic changes, such as withdrawing of the inhabitants to the interior for reasons other than volcanic effects. It is concluded from the pollen cores that no major climatic changes affected northwestern Crete during the Holocene but the first two millennia of the Holocene tended to be drier than the following period when there was an increase in moisture-demanding trees. It is difficult to assign changes in the Cretan vegetation to climatic effects in a period when human impact was gathering strength. [ABSTRACT FROM AUTHOR]

The idea that much environmental information may be gained by identifying underlying environmental system behaviours is examined. Six categories of system behaviour for changes between and within steady-states are identified: disorder maximization; self-organization; linear process-response; stochastic; self-organized criticality; and chaotic. In practical terms, predictability only exists for linear behaviour. Simple frequency distributions of time-series data are used to identify dominant behaviour in the proxy-records from 10 000 years of annual laminations from Holzmaar, Germany. The results suggest that before |3000 yr cal. BP the catchment-lake system may have reached a state of self-organized criticality where fluctuations in system properties, for instance diatom productivity and sediment flux, were caused by internal reorganization as much as by external forces. Comparison of the records for sediment flux with outputs from the GOLEM landscape model suggests that major shifts in the Holocene record were triggered by human actions rather than by climate. The approach offers a new perspective on the causes of minor and major changes in reconstructed environmental systems and the degree of interactions between subsystems. [ABSTRACT FROM AUTHOR]