Plant Macrofossil Assemblages Research Articles

Wildfire activity and impacts on palaeoenvironments during the late Paleozoic Ice Age - New data from the North China Basin

The Late Paleozoic is widely recognized as a ‘high-fire’ world. However, the impact of wildfires on the vegetational change as well as the relationship between fire and low atmospheric pCO2 and high pO2 in the Late Paleozoic remains a matter of debate. New data on fossil charcoal and pyrogenic PAHs in coal deposits from the Yuzhou Coalfield, the southern part of the North China Basin, are integrated into previous studies to increase our current understanding of the role of wildfires on land and in marine environments during the late Carboniferous and early Permian. Analyses of bulk petrographic and organic geochemical data indicate that during deposition of the Taiyuan Formation (late Gzhelian and early Asselian Stage) wildfires were more prevalent and were characterized by a large proportion of crown fire. A previous plant macrofossil assemblage study of the Taiyuan and Shanxi formations, together with fire traits of ancient plant lineages, indicates that wildfire may likely be one of the major drivers of the thriving of the Cathaysian Flora during this period. Wildfire and post-wildfire processes might have acted as important controlling factors for organic carbon burial. Persistent organic carbon sequestration (as coals or charcoal) on land and increasing organic carbon burial in the ocean are coincident with the peak in pO2 during the apex of the Late Paleozoic Ice Age.

A New Plant Macrofossil Assemblage from the Rhaetian–Hettangian Fosheim Member of the Heiberg Formation on Ellesmere Island, Arctic Canada

Previous articleNext article No AccessA new plant macrofossil assemblage from the Rhaetian-Hettangian Fosheim Member of the Heiberg Formation on Ellesmere Island, Arctic CanadaChristian Pott, Simon R. A. Kelly, Benjamin Bomfleur, and Simon SchneiderChristian Pott Search for more articles by this author , Simon R. A. Kelly Search for more articles by this author , Benjamin Bomfleur Search for more articles by this author , and Simon Schneider Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by International Journal of Plant Sciences Just Accepted Article DOIhttps://doi.org/10.1086/725108 Views: 6Total views on this site HistoryAccepted March 17, 2023 © 2023 The University of Chicago. All Rights reserved.PDF download Crossref reports no articles citing this article.

Paleo-vegetation and paleo-environment of the late Cenozoic plant macrofossil assemblages from the Lake Nukabira area, eastern central Hokkaido, Japan

北海道中央東部の糠平湖周辺に分布する十勝幌加層とタウシュベツ層から大型植物化石群を得た（十勝幌加およびタウシュベツ植物群）．当地域の層序と火山性堆積物の放射年代測定値から，タウシュベツ層は下部更新統に改められる．後期中新世の十勝幌加植物群は47分類群，前期更新世のタウシュベツ植物群は42分類群より構成され，両者ともに木本ではウダイカンバ類縁種を優占種とし，他のカバノキ科やカエデ属などの落葉広葉樹と常緑針葉樹を含む古植生を示す．両植物群では，含む分類群に相違も多いが，類似した相観の植生を示す．これは，両者が火山活動の影響や類似した湿潤冷温帯気候下で成立した可能性を示す．

65,000 years of changing plant food and landscape use at Madjedbebe, Mirarr country, northern Australia

The plant macrofossil assemblage from Madjedbebe, Mirarr Country, northern Australia, provides insight into human-plant relationships for the ∼65,000 years of Aboriginal occupation at the site. Here we show that a diverse diet of fruits, nuts, seeds, palm and underground storage organs was consumed from the earliest occupation, with intensive plant food processing in evidence. The diet varied through time as foraging strategies were altered in response to changes in environment and demography. This included a broadening of the diet during drier glacial stages, as well as changes in the seasonal round and incorporation of new foods with the formation of freshwater wetlands following sea level rise in the late Holocene. The foundations of the economy evidenced at Madjedbebe include seasonal mobility, a broad diet and requisite plant processing and grinding technologies, all of which are maintained throughout the entire timespan of occupation. This points to a resilient economic system in the face of pronounced environmental change.

Saltmarsh archives of vegetation and land use change from Big River Marsh, SW Newfoundland, Canada

Pollen and plant macrofossils are often well-preserved in coastal sediments, providing a palaeoenvironmental record of sea-level and landscape change. In this study, we examine the pollen and plant macrofossil assemblages of a well-dated saltmarsh sediment core from southwest Newfoundland, Canada, to establish recent coastal vegetation and land use change, to increase the knowledge of anthropogenic activities in the area and develop pollen chronozones for reconstructing marsh accumulation rates and to examine the representation of plant macrofossil remains in the wetland pollen profile. Grouping the pollen record into upland and wetland assemblages allows local events related to hydrological change to be separated from landscape-scale changes. The wetland pollen and plant macrofossil records indicate a general acceleration in sea-level rise ca. ad 1700. The sedge pollen and plant macrofossil records attest to multiple phases of rhizome encroachment during inferred periods of marine regression. Two chronozones are identified from the upland pollen profile; the first associated with the settlement of St. George’s Bay ca. ad 1800, signalled by increases in Plantago lanceolata and Ambrosia pollen; the second with the permanent settlement of the Port au Port peninsula ca. ad 1850, indicated by increased P. lanceolata and Rumex pollen. Comparison of the plant macrofossil and wetland pollen profiles highlights the underrepresentation of grass pollen preserved in the saltmarsh sediments and a need for further analysis of the zonation, pollen dispersal and macrofossil representation of sedge species in saltmarshes.

Assessing the uncertainties in climatic estimates based on vegetation assemblages: Examples from modern vegetation assemblages in the American Southwest

Assemblages of fossil plant remains have been widely used to reconstruct past climatic conditions, usually through the application of methods that involve either finding vegetation analogues on the modern landscape (and using the modern associated climatic values as the basis for an estimate) or using the modern climatic ranges of individual taxa in an assemblage to determine the range of a given climate variable that would allow these plant taxa to live together. Although these approaches are relatively straightforward, it is difficult to assess the uncertainties associated with each approach, particularly in regard to their application to plant macrofossil assemblages. To explore the uncertainty that may arise from inaccuracy and imprecision in climate reconstructions and from ecological considerations we used variants of both approaches to estimate climate from two data sets of modern vegetation assemblages from the southwestern United States: (1) 1752 gridded “virtual plant assemblages” based on plant range maps that provide uniform spatial coverage of the presence or absence of major woody plant taxa across the study area; and (2) 43 modern packrat (Neotoma spp.) midden presence-absence assemblages that are similar to fossil midden assemblages. By comparing observed and estimated climate values, we evaluated the quality of the climate estimates, identified sources of uncertainty, and characterized the nature and magnitude of the effects of these uncertainties on the climate estimates.Uncertainties in estimating climate from vegetation assemblages arise because any given plant taxon (or assemblage) must have the resiliency to survive a range of climatic variability, and because of the strong intercorrelations among climatic variables in the modern climate data. Additional sources of uncertainty in climate estimates from plant assemblages include: (1) the modern climate and plant distribution data that are selected as the basis for estimation; (2) the particular quantitative approach that is used to estimate climate; (3) the sufficiency of the number of taxa in the analysis for providing an unbiased representation of the vegetation community as it existed for each time period in the analysis; and, (4) the location of the assemblage on the climatic and environmental gradients in the calibration data set for each climate variable under consideration.We conclude that vegetation assemblages can provide valid and reproducible estimates of climatic variables and that the primary trends and mapped patterns in the observed climate data can be reconstructed from such estimates. However, many factors may affect the quality of an estimate from a given plant assemblage, including aspects of data selection, data adequacy, methodologies, and the location of the assemblage site relative to gradients in the base climate data. It is particularly difficult to accurately estimate extreme values in the observed climate data, because estimated values from either end of an observed climate gradient necessarily “move toward the middle” of the gradient. In addition, the interval chosen to represent modern climate (here we used 1961 to 1990) may have a large impact on the size of the estimated difference between modern and past climate at a given site.

Contribution of archaeobotany to understand taphonomic phenomena. The case of a Preboreal palaeochannel of Autrecourt-et-Pourron (Ardennes, France)

Palaeoecology, through the analysis of the interactions between environmental factors and ecosystems, refines the knowledge of the structuring process of plant communities and helps to understand the complexity of past environments. However, it is necessary to analyse the taphonomic phenomena (deposition, conservation, degradation) affecting plant macrofossil assemblages in order to perform relevant palaeoecological analyses. Indeed, plant macrofossils may be under or over-represented in carpological assemblages, depending on the resistance of their cell membranes and the sedimentary condition deposits. For this reason, it is necessary to estimate the representative quality of the conserved part as a source of information. Like all archaeological documents, the plant archives are distorted by the processes of formation of the sedimentary levels and, ignore the diagenetic history of the sedimentary layers could lead to wrong palaeoecological interpretations. To this aim, we analysed plant macrofossils contained in the wet sediments of a Meuse palaeochannel (Autrecourt-et-Pourron, Ardennes, France). This archaeobotanical study of an oxbow lake dated to the Preboreal (11.7–10.7 ka cal. BP), provides a reference of a taphonomic referential according to a hierarchy of organic remain preservations. This framework successfully helped the palaeoecological interpretations of the Autrecourt-et-Pourron off-site, and it has brought robustness to environmental history reconstruction of the early Holocene in the Ardennes Meuse.

A decrease in temperature during the late Middle Pleistocene interglacial stage (MIS 7.3) altered montane zone floral diversity: Plant macrofossil evidence from central Japan

Plant fossils from the Early and Middle Pleistocene have mainly been obtained from lowland sediments, and consequently, there is currently limited information on changes in montane zone vegetation prior to the last glacial stage. However, fossil plant assemblages occurring at high altitudes can be used to assess the influence of climate change on the vertical distribution of plants and vegetation. In this study, we analysed plant macrofossil assemblages from fluvial deposits in the upper Middle Pleistocene strata outcropping in a riverbed at 1160–1180 m a.s.l. in the southeastern foothills of Mt. Yatsugatake, central Japan. Ages of the assemblages were constrained by two widespread tephras that were detected above the interglacial peak of marine isotope stage (MIS) 7.3 (~212 ka). The annual mean temperature in the lower and middle sections of the profile was estimated to be warmer than that at present, based on the coldest temperatures limiting the distribution of Phytolacca japonica and Selaginella remotifolia, and the temperature decreased in the upper section. Since MIS 7.4, the fluctuation in plant altitudinal distribution has been exemplified by changes in the limits of S. remotifolia and Larix kaempferi distribution, and their coexistence at the same altitude varied depending on climate settings. Species diversity, estimated by rarefaction analysis of plant macrofossil assemblage composition, declined as temperatures decreased after the peak of MIS 7.3. Decreasing floral diversity during the subsequent cooling phase possibly coincided with a downward migration of the vegetation zone and extirpation of plants from the inland basin in central Japan.

Extinction debt and delayed colonization have had comparable but unique effects on plant community–climate lags since the Last Glacial Maximum

AbstractAimPlant communities typically exhibit lagged responses to climate change due to poorly understood effects of colonization and local extinction. Here, we quantify rates of change in mean cold tolerances, and contributions of colonization and local extinction to those rates, recorded in plant macrofossil assemblages from North American hot deserts over the last 30,000 years.LocationMojave, Sonoran and Chihuahuan Deserts.Time period30–0 thousand years before present (kybp).Major taxa studiedVascular plants.MethodsColonization and local extinction dates for 269 plant species were approximated from macrofossils in 15 packrat (Neotoma) midden series. Cold tolerances estimated from contemporary climate were used to quantify assemblage‐mean cold tolerances through time. Rates of colonization and local extinction, and their effects on rates of change in assemblage‐mean cold tolerances, were estimated for 30–20 kybp (Late Pleistocene, no directional warming), 20–10 kybp (deglaciation, rapid warming) and 10–0 kybp (Holocene, no directional warming).ResultsRates of change in all metrics were negligible during the Late Pleistocene. Rates of change in assemblage‐mean cold tolerances (mean 1.0°C × 10−4/yr) lagged behind warming during deglaciation, and continued at similar rates (1.2°C × 10−4/yr) throughout the Holocene. Colonization and local extinction contributed equally to delayed responses to warming, but their dynamics differed through time: Colonization by warm‐adapted species predominated during deglaciation, while the most heat‐adapted species exhibited long delays in colonization. Only the most cold‐adapted species went locally extinct during deglaciation, followed by slow repayment of the extinction debt of cool‐adapted species during the Holocene.Main conclusionsResponses to rapid warming can persist for millennia, even after cessation of warming. Consistent patterns from different midden series across the region support a metacommunity model in which dispersal interacts with environmental filters and buffers against local extinction to drive community–climate disequilibrium during and after periods of warming.

Hydrologic and anthropogenic influences on aquatic macrophyte development in a large, shallow lake in China

Abstract Macrophyte composition and abundance affect the overall ecological structure and function of lakes, and information on the nature and timing of changes in macrophyte assemblages is therefore crucial for understanding their impact on the lake ecosystem. We examined plant macrofossils, diatoms, cladocerans, and physical and geochemical proxies in two sediment cores from Lake Liangzi, a large shallow lake located on the Yangtze floodplain in south‐east China, in order to assess recent and historical trajectories of ecological and environmental change. We also used archival records of environmental changes (i.e. hydrological, climatic, fishery, and social factors) in the lake and its catchment. Lake Liangzi is of particular interest as it, unlike most other lakes in the region, has maintained a macrophyte‐dominated state. The results revealed a shift in the lake during the past ca. 160 years from a clear water, low‐growing submerged macrophyte community (e.g. Najas minor, charophyte species), dominated by planktonic diatoms and planktonic cladocerans, towards a more pollutant‐resistant, tall‐growing macrophyte community (Potamogeton spp., Ceratophyllum demersum and Myriophyllum spicatum) and dominance by benthic and epiphytic diatoms and littoral cladocerans. However, a pronounced increase in the abundance of planktonic Bosmina spp. at the expense of true littoral cladoceran species and a decline in plant macrofossil assemblages in the surface samples suggest that the lake recently entered into a new unprecedented state. Redundancy analysis indicated major changes in hydrology and moderate inputs of anthropogenic pollutants as well as climate warming as the main drivers of ecological and environmental changes in the lake. Our study demonstrated that plant macrofossils from radionuclide‐dated short sediment cores provide reliable information on the nature and timing of changes in the macrophyte community in Lake Liangzi. Furthermore, our study provided information on the composition of the plant community before recent strong perturbations and also showed the trajectories and suggested the drivers of ecological and environmental change, thereby offering valuable information for lake managers in the Yangtze region and elsewhere. Our study identifies a relatively resistant community of submerged macrophytes, which may be an initial restoration target for managers when restoring the many lakes in the region where submerged vegetation coverage has declined during the last few decades.

Plant macrofossil assemblages from surface sediment represent contemporary species and growth forms of aquatic vegetation in a shallow Mediterranean lake

Macrofossils are known as a useful tool in reconstructing their original plant communities. However, most studies have been focused on comparing the composition and distribution of living plant communities and their remains in temperate lakes. Mediterranean shallow lakes have been historically far less studied and little is known about the relationships between Mediterranean macrophyte communities and their remains. The aim of our study is to assess how contemporary aquatic macrophyte communities are represented by their sedimentary remains in terms of composition, distribution and concordance between the contemporary and the subfossil assemblages in a procrustean superimposition space, and to determine which surface sediment cores, collected along a depth gradient, may represent best the whole-lake macrofossil assemblage. These analyses were carried out for both species and macrophyte growth forms (submerged hydrophytes, floating-leaved hydrophytes, helophytes and charophytes) in order to check which of the two (species and growth forms) were represented best by their macro-remains. The most abundant present-day species (Myriophyllum alterniflorum DC. and Potamogeton trichoides L.) were under-represented while Characeae and some floating-leaved hydrophytes (Polygonum amphibium L. and Ranunculus peltatus Schrank) were over-represented in sedimentary samples. Additionally, macro-remains of submerged hydrophytes and helophytes were generally found in the central areas and in close proximity to contemporary vegetation, whereas floating-leaved hydrophytes distributed close to the near-shore. Notwithstanding some disparities between contemporary vegetation and their macrofossil assemblages, we found a good agreement between present-day and sedimentary datasets for both species and macrophyte growth forms. Furthermore, our study suggests that sediment cores from deep areas are more likely to represent best the whole-lake macrofossil assemblage because of their high diversity, equitability and heterogeneity. We conclude that aquatic macrophyte subfossils from the central areas of the basin can be a very useful tool in tracking the species composition and structure of the original macrophyte communities in shallow Mediterranean lakes. Additionally, when considering the use of macro-remains to reconstruct the composition and structure of macrophyte growth forms, we recommend a multicore approach that uses transects running from the shore to the lake center.

The first Pleistocene fossil records of Urtica kioviensis Rogow. (Urticaceae) and Potamogeton sukaczevii Wieliczk. (Potamogetonaceae) in the British Isles

Seeds of the extant Urtica kioviensis Rogow. (Urticaceae) and endocarps of the extinct Potamogeton sukaczevii Wieliczk. (Potamogetonaceae) were recorded in diverse plant macrofossil assemblages recovered from organic sediments exposed during excavations at Saham Toney, Norfolk, UK. Aminostratigraphical data show the sediments were deposited during the Ipswichian (Last Interglacial) Stage. Palynological data indicates deposition during the Carpinus pollen zone of the Ipswichian Stage—the latter part of pollen zone Ip IIb and Ip III. The records are noteworthy not only because they are the first in the British Pleistocene but also because of the geographical occurrences of these two species. Urtica kioviensis is absent from the British flora today and has a modern range in central and eastern Europe (only extending as far west as north–east Germany and Denmark), while the extinct Potamogeton sukaczevii has only been recovered from Late Pleistocene sediments in Belarus, Lithuania, Poland and western Russia. The presence of U. kioviensis along with other exotic species to the British Isles (e.g. Najas minor L. and Salvinia natans L., which today have central and southern ranges in Europe and in the case of S. natans occurs on other continents) may point to more continental conditions or warmer summer conditions during the second half of the Ipswichian Stage in southern Britain. No modern analogues occur in Britain for the assemblages recovered from Saham Toney. Evidence of colder winters or at least warmer summers at the time of deposition does not support the view that sea-level peaked in the Carpinus zone of the Eemian Stage (correlated with the Ipswichian Stage) associated with increased oceanicity. Southern Britain would have been under the influence of the Atlantic Ocean and a degree of oceanicity is supported by the presence of two thermophilous taxa, Hedera and Ilex, in the pollen spectra from Saham Toney. Alternative explanations for the presence of these exotic species are that they were tolerating mild winters and cooler summers at the time of deposition or exploiting suitable micro-environments. The distribution of P. sukaczevii is probably an artefact of the distribution of expertise in the identification of Potamogeton fossil endocarps rather than having any palaeogeographic or palaeoclimatic significance. It is an extinct ancestor of the extant P. maackianus A. Benn, an eastern Asian pondweed. Its discovery in Britain encourages a reassessment of plant macrofossil assemblages from western Europe, which may lead to a consideration of the relationship between the Late Pleistocene vegetation of Europe and eastern Asia.

Environmental and climatic conditions of human occupation in the central East European Plain during the Middle Holocene: Reconstruction from palaeofloristic data

Paleobotanical assemblages from peat, lake, and archaeological deposits reveal that during the Middle Holocene (MH; ca. 9.0 to 4.7 kyr BP), the central East European Plain was occupied by highly productive and diverse mixed-oak forests, along with mire, meadow, and riverine communities. Climatic reconstructions based on modern analogues of fossil pollen and plant macrofossil assemblages indicate that throughout the MH mean annual precipitation was at near-present levels (∼600 mm) and July temperatures were similar to those of today (∼17 °C). However, differences in the Fossil Floras (FFs) suggest changes in winter conditions though the MH, with January temperatures higher than the present-day value of −10 °C by 2 °C in the Early Atlantic (FF1), 6 °C in the Middle Atlantic (FF2), and 3 °C in the Late Atlantic-Early Subboreal (FF3). The annual frost-free period was 15 days longer than today in the Early Atlantic, about one month longer in the Late Atlantic, and became close to present by the beginning of the Subboreal. The combination of warm winters with diverse and productive vegetation communities provided an environment that was more hospitable than that of today for Late Mesolithic and Neolithic societies.

Vegetation and climate histories between MIS 63 and 53 in the Early Pleistocene in central Japan based on plant macrofossil evidences

Among the Early Pleistocene fluvial sediments in Japan that yield plant macrofossils, the Uonuma Group in the Niigata sedimentary basin provides the most continuous profile without any conspicuous hiatuses and is therefore suitable for high-resolution reconstructions of environmental and vegetation histories based on tephro- and magneto-stratigraphy. Based on the species composition of plant macrofossil assemblages, along with previously reported results on sedimentary environments and pollen records, we performed a reconstruction of changes in paleovegetation and paleotemperatures between MIS 63 and 53. Macrofossil assemblages identified from 33 samples include 89 arboreal and 88 herbaceous taxa in total, of which 9 taxa are extinct from Japan. Assemblages from the peat deposits in fluvial backmarshes during glacial stages are composed mainly of wetland herbaceous plants, whereas those from the sandy channel-fill deposits are characterized by a higher diversity in life forms and habitat preferences. During the interval from MIS 63 to 53, paleotemperatures fluctuated between a coldest-month mean temperature of −4.6 °C and −0.9 °C and between a mean annual temperature of 6.6 °C and 11.0 °C, which is within the present range for cool-temperate, deciduous broad-leaved forests in Japan. MIS 60 was the coldest of the glacial stages with temperatures nearly equivalent to those during the last glacial maximum. Major plant extinctions in and around MIS 60 were not recorded in the sedimentary basin in response to the temperature decline. The relatively indistinct floral changes in and around MIS 60 are attributed to easier recovery of flora by migration from glacial refugia in the southern basins after termination of the glacial stage. Interglacial temperatures during MIS 57, 55, and 53 were higher than during MIS 63, 61, and 59. The presence of a maritime environment during the interglacial periods between MIS 57 and 53 may have resulted from a greater extent of marine transgression and heat provided by the Tsushima Warm Current flowing into the Sea of Japan after MIS 59.

Temperate deciduous broadleaf forest dynamics around the last glacial maximum in a hilly area in the northern Kanto district, central Japan

Research into the geographical distribution of temperate tree refugia and their associated environmental conditions during glacial stages is necessary to understand the processes by which the present vegetation and plant distributions developed. On the basis of pollen and plant macrofossil assemblages deposited in a small valley in a hill in the northern Kanto district in central Japan, we reconstructed the local and regional vegetation changes in and around the distribution range limit of temperate broadleaf trees during the latest stage of marine isotope stage (MIS) 3 (36.2–32.8 ka) and around the late stage of the last glacial maximum (LGM) (23.4–16.6 ka). During the latest stage of MIS 3, the local and regional vegetation in and around the hill was composed of temperate deciduous broadleaf forest dominated by Quercus subgen. Lepidobalanus and mixed with pinaceous conifers. The proportion of deciduous broadleaf trees in the regional vegetation increased during recurring warm and humid phases that were correlated with Greenland D-O 7, 6, and 5 warming events. During the LGM, coniferous forests composed of Picea jezoensis var. hondoensis, Tsuga diversifolia, Abies veitchii, and Betula ermanii, which are major components of the present subalpine forests in central and western Japan, expanded in hilly and mountain zones in central Japan. Refugia of temperate broadleaf trees existed at altitudes up to that of the study site and were limited to mesic places along the valley bottom. At the termination of the LGM around 18.8 ka, a biome shift to mixed coniferous and deciduous broadleaf forest dominated by Betula occurred in and around the study site. The expansion of deciduous broadleaf trees at ca. 19 ka, which has also been recognized in other localities in central Japan, may have been triggered by an increase in precipitation during the stage wherein summer insolation became greater. The temperate broadleaf trees that have been distributed in hilly-zone refugia were sensitive to warming at the termination of the LGM.

Paleovegetation and palaeotemperature around MIS 7.3, late Middle Pleistocene, reconstructed from plant macrofossil assemblages at the southeastern foot of Mt. Yatsugatake, central Japan

Paleovegetation and palaeotemperature around MIS 7.3, late Middle Pleistocene, reconstructed from plant macrofossil assemblages at the southeastern foot of Mt. Yatsugatake, central Japan

Development history of Sarufutsugawa mires, northern Hokkaido, Japan, reconstructed from plant macrofossil assemblages

Development history of Sarufutsugawa mires, northern Hokkaido, Japan, reconstructed from plant macrofossil assemblages

Archaeobotanical records of Middle and Late Neolithic agriculture from Shandong Province, East China, and a major change in regional subsistence during the Dawenkou Culture

As heated debates about the origin of rice domestication and cultivation in southern and eastern China continuously attract attention of the broad scientific community, new evidence for early rice exploitation from the regions located outside the core area of domestication, the lower Yangtze, are very important. Here, we present new archaeobotanical results of plant macrofossil and phytolith analyses, including directly dated rice grains from the sites of Dongpan (4030–3820 cal. BC) and Beiqian (3700–2900 cal. BC). These results fill (at least partly) an existing gap between the c. 8000-year-old rice remains from the Early Neolithic Houli Culture ( c. 6500–5500 BC) sites north of the Shandong Highlands and the Longshan Culture ( c. 2600–1900 BC) sites, where intensive rice agriculture was practiced. Neither rice nor millet made substantial contribution to the plant macrofossil assemblage at Dongpan, while broomcorn (and to a lesser extent foxtail) millet contributed up to 75% to the macrofossil assemblage at Beiqian. This increase can be interpreted as a major change in regional subsistence from strongly relying on wild resources and small scale cultivation during the Beixin Cultural period to a millet-based economy during the Dawenkou Culture.

Paleovegetation and climatic conditions in a refugium of temperate plants in central Japan in the Last Glacial Maximum

Paleovegetation and climatic conditions in the Last Glacial Maximum (LGM; ca. 24.4 and 20.1 ka) were reconstructed based on plant macrofossils and pollen assemblages deposited in a sandy channel outcropped in the Hanamuro River, Ibaraki Prefecture, central Japan. The plant macrofossil assemblages were composed of 31 arboreal and 76 herbaceous taxa. Occurrence of plants with various habitat preferences exhibited distribution patterns of highly diverse vegetation types depending on geomorphology and humidity in and around the drainage of the Hanamuro River. Rich aquatic and wetland flora indicates an expansion of backmarsh mosaic environments along the river channel in the bottom of the valley. Wetland forests composed of Picea sect. Picea assignable to Picea koyamae, and riparian forests dominated by Alnus inokumae, are well represented in the macrofossil assemblages. Pinaceous conifers were dominant in mesic or dry places with Betula and the other deciduous broadleaved trees. Macrofossils and pollen indicates that Abies veitchii was distributed in mesic locations, Larix kaempferi and Picea jezoensis var. hondoensis were on the upper slopes, and Pinus koraiensis was dominant on the plateau. Dominant Selaginella remotifolia and the other drought-intolerant understory herbs indicate closed canopy of mesic coniferous forests, while many kinds of meadow and/or ruderal plants were indicative of open vegetation along the river and slopes. Annual mean temperature of the fossil site based on occurrence of Selaginella remotifolia was 8.1 °C, which is observed in present cool temperate zones where deciduous broad-leaved trees are dominant. This indicates that the distribution limit of subarctic conifers shifted to warmer temperature conditions than at present. The overlapping distribution of temperate and subarctic plants occurred widely in the lowlands in the distribution ranges of temperate trees, south of around 38° N in Japan. In the LGM, with lower precipitation, dryness was an important environmental factor that controlled plant distribution along with temperature. Water stress confined temperate broad-leaved trees to the humid valley bottoms and relieved conifers from competition against broad-leaved trees to promote their expansion to warmer regions. Macrofossils indicate the persistence of temperate plants in humid inland and/or northern refugia during the LGM, locations conducive to Paleolithic human occupation.

Palaeovegetation of Honghe wetland in Sanjiang Plain as a basis for conservation management and restoration

This paper documents the history of vegetation assemblage in Honghe Wetland (NE China) during the last 6200 years. Vegetation changes were reconstructed based on high-resolution plant macrofossil analysis of sedimentary sequence obtained from Honghe National Nature Reserve located in Sanjiang Plain, in conjunction with Accelerator Mass Spectrometry (AMS) 14C radiocarbon data. Results indicate that plant macrofossil composition of Honghe wetland ecosystem are dynamic and have undergone several significant changes. Around 2500cal yr BP, plant composition transited from Equisetum fluviatile community to Carex lasiocarpa- Drepanocladus aduncus community, and then following by Drepanocladus aduncus community at 460cal yr BP. Another major vegetation changes occurred at 220cal yr BP, transitioning to Carex sp. community. By comparison between the plant macrofossil assemblages and the climate changes during the last 6200cal yr BP, we suggest that ASM (Asian summer monsoon) is the main driving force for the vegetation succession before the impacts of human activities. Since some restoration programs have been undertaken at Honghe wetland, thus our results can provide valuable baseline data for assessment of the practicability and suitability of the former restoration plan and the further designing of conservation management and restoration targets. Since the vegetation composition of Honghe wetland is pronouncedly sensitive to water level, it can be inferred that wetland ecosystem can be restored to near-natural condition through the effective management and restoration by controlling the water source of the wetland.