Holocene Environmental History Research Articles

Late Glacial and Holocene environmental history of the Ethiopian Highlands inferred from a 12 m long sediment record from Dendi crater lakes

Quaternion-valued wireless communication systems have been studied in the past. Although progress has been made in this promising area, a crucial missing link is lack of effective and efficient quaternion-valued signal processing algorithms for channel equalization and beamforming. With most recent developments in quaternion-valued signal processing, in this work, the author fills the gap to solve the problem by studying two quaternion-valued adaptive algorithms: one is the reference signal based quaternion-valued least mean square (QLMS) algorithm and the other one is the quaternion-valued constant modulus algorithm (QCMA). The quaternion-valued Wiener solution for possible block-based calculation is also derived. Simulation results are provided to show the working of the system.

The Holocene deglaciation of the Byers Peninsula (Livingston Island, Antarctica) based on the dating of lake sedimentary records

The process of deglaciation in the Antarctic Peninsula region has large implications for the geomorphological and ecological dynamics of the ice-free environments. However, uncertainties still remain regarding the age of deglaciation in many coastal environments, as is the case in the South Shetland Islands. This study focuses on the Byers Peninsula, the largest ice-free area in this archipelago and the one with greatest biodiversity in Antarctica. A complete lacustrine sedimentary sequence was collected from five lakes distributed along a transect from the western coast to the Rotch Dome glacier front: Limnopolar, Chester, Escondido, Cerro Negro and Domo lakes. A multiple dating approach based on 14C, thermoluminescence and tephrochronology was applied to the cores in order to infer the Holocene environmental history and identify the deglaciation chronology in the Byers Peninsula. The onset of the deglaciation started during the Early Holocene in the western fringe of the Byers Peninsula according to the basal dating of Limnopolar Lake (ca. 8.3cal.ky BP). Glacial retreat gradually exposed the highest parts of the Cerro Negro nunatak in the SE corner of Byers, where Cerro Negro Lake is located; this lake was glacier-free since at least 7.5ky. During the Mid-Holocene the retreat of the Rotch Dome glacier cleared the central part of the Byers plateau of ice, and Escondido and Chester lakes formed at 6cal. ky BP and 5.9ky, respectively. The dating of the basal sediments of Domo Lake suggests that the deglaciation of the current ice-free easternmost part of the Byers Peninsula occurred before 1.8cal.ky BP.

Late Glacial and Holocene environmental history on the eastern slope of the Middle Ural mountains, Russia

The study area is situated on the eastern slope of the Middle Urals, at an elevation of 250–300 m above sea level, in pine forests of the southern taiga subzone. The modern climate is temperate continental. In order to assess the Holocene environmental dynamics, a study of peat bog deposits by means of palynological and paleobotanical analyses, coupled with radiocarbon dating is undertaken. The article presents the results of a multi-proxy study of five sections of Shigirskiy and Gorbunovskiy peat bogs, the former post-glacial lakes changed into peat bogs during the Holocene. The study is coupled with archaeological investigations of the cultural layers in peat and sapropel, which represent the traces of settlements on the banks and islands. A total of 179 samples are subjected to palynological and botanical analyses and the radiocarbon dates are obtained on 29 samples of peat and sapropel. The peat bog stratigraphy, sedimentation processes, environmental dynamics and ancient human activities are characterized for the period from the end of Late Glacial throughout the Holocene. The three periods of the most significant climatic changes are established for the study area. 1) The warming and beginning of the spread of arboreal vegetation at the boundary between the Late Glacial and Eraly Holocene about 11 thousands calendar years ago, or 11 ka; 2) the substantial warming between 9.3 and 8.6 ka resulted in the wide spread of pine and formation of mixed forests with broad-leaved trees; 3) an abrupt decrease of spruce and broad-leaved arboreal plants in forest communities, indicating a dry cooling at about 4.2–3.8 ka. Those periods are related to the changes of archaeological epochs. The other three periods of climate aridification are established by the decreasing spruce frequencies in the pollen spectra and the transition from sapropel to peat due to lowering water levels in the lakes at about 8.3–7.8, 6.2–5.8, and 5.4 ka. The formation of cultural layers was related to the dry periods and the reduced levels of ground waters, which promoted the human use of the peatlands. The results are presented as a table summarizing the environmental dynamics over the background of the calendar age of deposits and are correlated to the Blytt-Sernander periodization of the Holocene in Northern Eurasia modified by Khotinsky (1977) and the formal tripartite subdivision of the Holocene (Walker et al., 2012).

Recent environmental history of the desert oasis lakes at Ounianga Serir, Chad

The Sahara desert oasis of Ounianga Serir in northern Chad comprises seven shallow but perennial lakes, which are maintained against an extremely negative local moisture balance by continuous inflow of fossil groundwater from the Nubian Sandstone Aquifer. Here we analyze the lithostratigraphy, charcoal, and fossil mollusks in short, dated sediment cores from three of these lakes (Edem, Hogou, and Agouta) to assess the hydrological and environmental stability of these unique aquatic ecosystems over the last few centuries. Our results indicate that the studied lakes remained relatively stable and fresh over the past 200–600 years, confirming the dominant and constant nature of groundwater input, preventing desiccation. Modest lake-level fluctuations did occur but were not synchronous between the lakes, arguing against climate variability being their primary cause. Likely, their site-specific history was determined by variations in groundwater through-flow, influenced by migration of sand dunes separating the lakes. The desert setting is responsible for characteristic lacustrine sediments comprised of carbonate mud with silt and sand. The associated fossil assemblages of freshwater mollusks suggest that the present-day mollusk fauna of Ounianga Serir may be more species-rich than previously thought. Our data expand the known distribution of the Palaearctic snail Valvata nilotica markedly south and westward into the central Sahara.

Geomorphic and sedimentary responses of the Bull Creek Valley (Southern High Plains, USA) to Pleistocene and Holocene environmental change

Fluvial geomorphology and stratigraphy often reflect past environmental and climate conditions. This study examines the response of Bull Creek, a small ephemeral creek in the Oklahoma panhandle, to environmental conditions through the late Pleistocene and Holocene. Fluvial terraces were mapped and their stratigraphy and sedimentology documented throughout the course of the main valley. Based on their elevations, terraces were broadly grouped into a late-Pleistocene fill terrace (T3) and two Holocene fill-cut terrace sets (T2 and T1). Terrace systems are marked by similar stratigraphies recording the general environmental conditions of the time. Sedimentary sequences preserved in terrace fills record the transition from a perennial fluvial system during the late glacial period and the Younger Dryas to a semiarid environment dominated by loess accumulation and punctuated by flood events during the middle to late Holocene. The highest rates of aeolian accumulation within the valley occurred during the early to middle Holocene. Our data provide significant new information regarding the late-Pleistocene and Holocene environmental history for this region, located between the well-studied Southern and Central High Plains of North America.

Lateglacial and Holocene environmental history in the area of Samogitian Upland (NW Lithuania)

Pollen, plant macrofossil and carbonate analyses supplemented with 14C dating were applied for Lopaičiai hollow and Pakastuva Lake sediment sequences. The new data obtained from two sediment cores were used to reconstruct vegetation cover and environmental changes during Lateglacial and Holocene in Samogitian Upland (NW Lithuania). Different burial conditions of dead ice blocks caused different time of lake sediment start in studied sites. The depositional and vegetation cover history is traced starting at pre-Allerød time in sediment sequence from Lopaičiai core. However, sediment sequence from Pakastuva core provides paleoenvironmental information starting only from the very beginning of Holocene. The study results bring more light on environmental development during Lateglacial and Holocene of specific ice marginal area, which is interlobate insular upland.

In Search of a Useable—and Hopeful—Environmental Narrative in the Mid-Atlantic

ABSTRACT Beyond a survey of some of the most recent traditional and public environmental history scholarship and trends in the Mid-Atlantic, this article—drawing from and reinterpreting the Turner Frontier Thesis—argues that the region both embodies broad currents of US environmental history and helped to establish American attitudes and patterns of behavior that migrated westward and shaped the course of national development. The article suggests that a Mid-Atlantic environmental history marked by such stories as mountaintop removal coal mining, urbanization, industrial disaster, environmental injustice, and the despoliation and ongoing recovery of rivers and watersheds like the Chesapeake and the Hudson is not only “typically” but “exceptionally” American. Further, the author notes that geography, environment, and natural resource history have shaped and informed heritage areas and other important recent work in public history, seeing in those trends the genesis of an era in which regional and subbioregional environmental histories can help inform and inspire new directions toward a more hopeful and sustainable future.

The Holocene environmental history of a small coastal lake on the north-eastern Kamchatka Peninsula

A radiocarbon and tephra-dated sediment core from Lifebuoy Lake, located on the north-east coast of Kamchatka Peninsula, was analysed for pollen, spores, diatoms, chironomids and tephra in order to uncover regional environmental history.The 6500-year environmental history of Lifebuoy Lake correlates with the broad regional patterns of vegetation development and climate dynamics with both diatoms and chironomids showing near-synchronous changes.Between ca. 6300 and 3900calyrBP, the lake ecosystem was naturally enriched, with several Stephanodiscus species dominating the diatom plankton. This natural eutrophication state is likely to be due to a combination of the base-rich catchment geology, the fertilisation effect of several fires in the catchment, silica input from tephra layers and, possibly, nitrogen input from seabirds. The substantial tephra deposit at about 3850calyrBP might have stopped sedimentary phosphorus from entering the lake water thus decreasing the trophic state of the lake and facilitating the shift in diatom composition to a benthic Fragiliariaceae complex.Both diatoms and chironomids showed simultaneous compositional changes, which are also reflected by statistically significant changes in their rates of change 300–400years after the arrival of Pinus pumila in the lake catchment. The rapid increase in both total diatom concentration and the percentage abundance of the large heavy species, Aulacoseira subarctica might be a response to the change in timing and intensity of lake spring turn-over due to the changes in the patterns of North Pacific atmospheric circulation, most notably westward shift of the Aleutian Low.The two highest peaks in A. subarctica abundance at Lifebouy Lake occurred during opposite summer temperature inferences: the earlier peak (3500–2900calyrBP) coincided with warm summers and the latter peak (300calyrBP–present) occurred during the cold summer period. These imply that A. subarctica shows no direct response to the changes of summer air temperature. Instead, it appears to thrive during the periods of increased winter precipitation, thicker ice and late spring turn-over periods, i.e., shows indirect response to climate.The clearest effect of tephra deposition on the lake ecosystem is above 908cm (ca. 3800calyrBP) where the tephra deposit might have caused the shift from Stephanodiscus-dominated planktonic assemblages to the Fragilariaceae complex of benthic species. Tephra deposits might have also contributed towards the development of eutrophic plankton from about 6300calyrBP. It is not certain if several tephra deposits influenced diatom and chironomid changes during the last 300years.

Holocene ice dynamics and bottom-water formation associated with Cape Darnley polynya activity recorded in Burton Basin, East Antarctica

A multi-proxy study including sedimentological, mineralogical, biogeochemical and micropaleontological methods was conducted on sediment core PS69/849-2 retrieved from Burton Basin, MacRobertson Shelf, East Antarctica. The goal of this study was to depict the deglacial and Holocene environmental history of the MacRobertson Land–Prydz Bay region. A special focus was put on the timing of ice-sheet retreat and the variability of bottom-water formation due to sea ice formation through the Holocene. Results from site PS69/849-2 provide the first paleo-environmental record of Holocene variations in bottom-water production probably associated to the Cape Darnley polynya, which is the second largest polynya in the Antarctic. Methods included end-member modeling of laser-derived high-resolution grain size data to reconstruct the depositional regimes and bottom-water activity. The provenance of current-derived and ice-transported material was reconstructed using clay-mineral and heavy-mineral analysis. Conclusions on biogenic production were drawn by determination of biogenic opal and total organic carbon. It was found that the ice shelf front started to retreat from the site around 12.8 ka BP. This coincides with results from other records in Prydz Bay and suggests warming during the early Holocene optimum next to global sea level rise as the main trigger. Ice-rafted debris was then supplied to the site until 5.5 cal. ka BP, when Holocene global sea level rise stabilized and glacial isostatic rebound on MacRobertson Land commenced. Throughout the Holocene, three episodes of enhanced bottom-water activity probably due to elevated brine rejection in Cape Darnley polynya occured between 11.5 and 9 cal. ka BP, 5.6 and 4.5 cal. ka BP and since 1.5 cal. ka BP. These periods are related to shifts from warmer to cooler conditions at the end of Holocene warm periods, in particular the early Holocene optimum, the mid-Holocene warm period and at the beginning of the neoglacial. In contrast, between 7.7 and 6.7 cal. ka BP, brine rejection shut down, maybe owed to warm conditions and pronounced open-water intervals.

A Late Holocene environmental history of a bat guano deposit from Romania: an isotopic, pollen and microcharcoal study

A 1.5-m-long core from a bat guano deposit in Zidită Cave (western Romania) has provided a 900-year record of environmental change. Shifts in δ13C values of bulk guano (between −22.6 and −27.5‰) combined with guano-sourced pollen and microcharcoal information show significant changes in the structure of vegetation and plant biomass. Cave guano δ13C values reflect the dietary preferences of bats which are controlled by local vegetation dynamics, which in turn depend on local climatic conditions. Neither δ13C values nor pollen association in guano changed strikingly over the Medieval Warm Period (MWP) and Little Ice Age (LIA) transition. Instead, an overall decreasing trend of δ13C values between ca. AD 1200 and 1870–1900 defines the duration of LIA. A shift toward cooler and wetter conditions at ca. AD 1500 noticed in the pollen record by an increase in Fagus sylvatica and Alnus and the decrease of Carpinus betulus, may indicate the first major change at the beginning of the LIA. Evidence for two major cold spells occurring around AD 1500 and ca. AD 1870 comes from both δ13C and pollen record. In between these events, the cave region experienced a warmer and drier climate but colder and wetter than the MWP, favouring the expansion of Quercus, Fraxinus and Tilia simultaneously with the decrease of F. sylvatica and Poaceae. Human impact in the studied area is mainly related to agriculture, grazing and deforestation. The effects are most pronounced after AD 1845 when the pollen of cereals increases and Zea is recorded (AD 1845). Higher percentages of microcharcoal particles in the guano sequence are generally correlated with agricultural activities like land cleaning via controlled fires.

Phylogenetic relationships among Synallaxini spinetails (Aves: Furnariidae) reveal a new biogeographic pattern across the Amazon and Paraná river basins

Relationships among genera in the tribe Synallaxini have proved difficult to resolve. In this study, I investigate relationships among Synallaxis, Certhiaxis and Schoeniophylax using DNA sequences from the mitochondrion and three nuclear regions. I implemented novel primers and protocols for amplifying and sequencing autosomal and sex-linked introns in Furnariidae that resolved basal relationships in the Synallaxini with strong support. Synallaxis propinqua is sister to Schoeniophylax phryganophilus, and together they form a clade with Certhiaxis. The results are robust to analytical approaches when all genomic regions are analyzed jointly (parsimony, maximum likelihood, and species-tree analysis) and the same basal relationships are recovered by most genomic regions when analyzed separately. A sister relationship between S. propinqua, an Amazonian river island specialist, and S. phryganophilus, from the Paraná River basin region, reveals a new biogeographic pattern shared by at least other four pairs of taxa with similar distributions and ecologies. Estimates of divergence times for these five pairs span from the late Miocene to the Pleistocene. Identification of the historical events that produced this pattern is difficult and further advances will require additional studies of the taxa involved and a better understanding of the recent environmental history of South America. A new classification is proposed for the Synallaxini, including the description of a new genus for S. propinqua.

Holocene environmental history at the treeline in the Northern Apennines, Italy: A micromorphological approach

The aim of this work is to investigate paleoenvironment at treeline quotas through the help of soil micromorphology. It also assesses how the micromorphological approach can provide information in paleoenvironmental studies where paleosols are available as proxy archives. Nine soil profiles are described across the treeline, between 1723 and 1860 m, on Mt Cusna slope (2121 m a.s.l., Northern Apennines, Italy). Undisturbed samples from selected soil horizons are collected in Kubiëna boxes. From field observations, all the profiles appear to be composed of two main pedogenetic units: the upper one, composed of a recent soil of colluvial origin, and the deeper one, consisting of an underlying more developed buried paleosol. Thin sections give detailed information about the nature and the origin of both pedological units. Four principal phases of paleosol development are detected. A first period of temperate climate with forest cover and contrasted seasons is followed by a phase of change and then by a successive decrease of forest cover. In a last phase, the soil experiences frost action under the effect of a colder climate. The final deposition of colluvium seems to be very recent (historical time). Moreover, multiple colluvial layers are identified. Colluvial material of different origins could be identified as part of dismantled soils similar to the preexisting paleosol. In conclusion, with the help of soil micromorphology, it is possible to assess the existence of past stable forest at least 100 m above the present treeline. The micromorphological approach represents a powerful tool in multidisciplinary paleoenvironmental studies due to its high level of resolution in outlining the individual and successive phases of soil evolution.

Robert L. Perlman, Evolution & Medicine

Robert L. Perlman, Evolution & Medicine

Holocene environmental change in subarctic aeolian dune fields: The chronology of sand dune re-activation events in relation to forest fires, palaeosol development and climatic variations in Finnish Lapland

Sand dune stratigraphy, radiocarbon-dated charcoal layers, palaeosol development and luminescence dating are used to reconstruct the Holocene environmental history of the dune fields in Finnish Lapland since deglaciation in the early Holocene (~10,900–10,200 cal. BP). After rapid formation and stabilisation of parabolic dunes and the immigration of Scots pine ( Pinus sylvestris), forest fires are inferred to have played a key role in triggering episodes of aeolian erosion of the dunes (deflation) leading to 16 sand dune re-activation events. These events were widespread in the dune fields from ~8300 cal. BP and occurred with increasing frequency towards the late Holocene. Each event is interpreted as relating to local fires that occurred up to 100–400 years after the date of each charcoal layer; the radiocarbon age of the charcoal being affected by the age of the wood when burned, and the accumulation and/or recycling of charcoal from earlier fires. Well-developed buried iron podzols, which can develop within 500–1000 years, indicate prolonged phases of dune stability, four of which are dated to between 4500 and 1050 cal. BP. Indirect associations are evident between the sand dune re-activation events and climatic phases that were relatively cold and/or wet. These associations are explained by a conceptual geo-ecological model in which the effects of century- to millennial-scale climatic variability are modulated by the interactions between fire and vegetation. Thus, the subarctic dune field is viewed as a heterogeneous landscape of stable and unstable areas in space and through time. The unstable elements of this spatial mosaic become more extensive at times when the climatic environment promotes fire and deflation.

Holocene sediment record from Briaunis palaeolake, Eastern Lithuania: history of sedimentary environment and vegetation dynamics

This paper presents new data describing the Holocene environmental history of the Briaunis palaeolake, Eastern Lithuania. Shortly before 9600 cal yr BP, sedimentation began in an oligotrophic deep-water basin, whereas the Early Holocene instability of the environmental regime caused the influx of detrital sediment into the basin. A birch forest dominated in the surrounding landscapes, and at ca. 9600 cal yr BP, the spread of Ulmus, Alnus, Populus and Corylus began, suggesting a short-lived climatic amelioration. A subsequent drop of the water table and increasing influx of the terrigenous material continued from 9600 to 9300–9200 cal yr BP. The ensuing climatic stability caused the formation of a deciduous forest and the regional spread of Picea. Some instability, i.e. a decline in the thermophilous species, as well as the appearance of boreal and northern alpine diatoms, could be associated with the so-called “8.2 ka event”. This reversal was followed by amelioration and prospering of the water plants typical of the Holocene climatic optimum from 7900 to 7200–7100 cal yr BP. At aproximatelly 6600–6500 cal yr BP, a small rise of the water table was documented and bog-forming processes dominated until ca. 3600–3400 cal yr BP, when a small-scale deepening of the basin occured.

Gone with the Trees: Deciphering the Thar Desert’s Recurring Droughts

In the 10-year period between 1999 and 2009, the district of Barmer, located in the Marwar region of Rajasthan, India, experienced 7 years of rainfall deficits, as well as instances of excessive rainfall. This increased variability in rainfall patterns in an area largely covered by the Thar Desert ‘has exacerbated the region’s already precarious environmental and land conditions. This article is based on ethnographic research conducted in this part of India, which is impacted by the numerous social, economic, and environmental outcomes of successive extreme weather events. It discusses the transformation of the ecosystem of the Thar Desert by drawing the outlines of the recent environmental history and by exposing local farmers’ articulation of these changes. The meanings and subjectivities with which rural Rajasthan is endowed and which constitute farmers’ identity are also addressed through the examination of the cultural construction of place. The analysis reveals that people’s understanding of environ...

Holocene environmental history of the Aishihik Region, Yukon, Canada

A 2.7 m sediment core from WA01, a small pond in Southwest Yukon, Canada (unofficial name, 61°14′41″N, 136°55′35″W, 1000 m above sea level), documents the postglacial vegetation and climate history of the Aishihik Basin. Open birch–shrub tundra established at the site ca. 10 900 cal years BP, immediately after deglaciation. Picea glauca established ca. 10 200 cal years BP, and an open spruce forest ecosystem has since remained dominant on the landscape. A gradual increase in Alnus crispa, starting ca. 6600 cal years BP, has also been noted in other studies from Central Yukon, suggesting a significant climate transition in Yukon at this time. An alternating pattern in sediment loss-on-ignition, also beginning ca. 6600 cal years BP, may be broadly related to trends in ∂18O values from the Mount Logan and Jellybean Lake oxygen isotope records, and is most likely reflective of periodic changes in available moisture in the region resulting from alterations in the strength and position of the Aleutian Low pressure system. However, millennial-scale climate variability identified in ice core and sediment records had little impact on the forests of the region.

46 years of environmental records from the Nevado Illimani glacier group, Bolivia, using digital photogrammetry

AbstractThis study determines variations in ice extent of Nevado Illimani, Bolivia (16°38' S, 67°44' W), from 1963 to 2009. The results are compared with net accumulation rate variations obtained from a local ice core. We then propose an interpretation of the recent environmental history (last 46 years) of the region based on a study of remotely sensed and ice-core data. From 1963 to 2009, Nevado Illimani lost a total ice area of 9.49 ±1.09 km2, a 35% reduction. Area variations generally followed variations in net accumulation rates during this period. Despite the current glacier area reduction trend, the Nevado Illimani glaciers will not completely disappear in the next few decades.

“Fire and Society in Modern China: Fire Disasters and Natural Landscapes in East Asian Environmental History” (1820-1965)

Land clearance and agriculture have long been associated with fire. Open fire, whether from natural or human ignition, has changed the face of many natural landscapes, especially in frontier regions. Much of modern China’s landscape has been shaped by fire, yet fire has been treated as a “disaster” (<em>huozai</em>) in official literature. However, fire in Chinese agriculture also played a positive role in the development of regional economies. This essay will review different meanings of “fire disasters” in recent Chinese environmental history by analyzing a few illustrative examples of late Imperial to Mao-era agricultural development, warfare, and legal institutions. By examining these elements of fire-culture landscapes, this paper will consider problems and management practices of Chinese environmental history, especially distinct ethnic, regional, and temporal trends in legal and administrative forms of fire control. These examples enable us to examine aspects of China military, agricultural, and social and ethnic history that lend themselves to cross cultural and environment comparison.

Lateglacial and early Holocene environmental history of the southern Vosges mountains, North-East France

Lateglacial and early Holocene environmental history of the southern Vosges mountains, North-East France