scholarly journals Vegetation Changes Viewed from Pollen Analysis in Rarotonga, Southern Cook Islands, Eastern Polynesia

Radiocarbon ◽  
2014 ◽  
Vol 56 (2) ◽  
pp. 699-708 ◽  
Author(s):  
Toshiyuki Fujiki ◽  
Mitsuru Okuno ◽  
Hiroshi Moriwaki ◽  
Toshio Nakamura ◽  
Kei Kawai ◽  
...  
Keyword(s):  
Human Impacts ◽  
Pollen Grains ◽  
Cultivated Plants ◽  
Vegetation Changes ◽  
Human Influence ◽  
Higher Plant ◽  
Radiocarbon Dates ◽  
Cook Islands ◽  
Core Sediments ◽  
Plant Fragment

This study presents accelerator mass spectrometry (AMS) radiocarbon dates and pollen assemblages of 400-cm core sediments collected from the Karekare Swamp in Rarotonga, Southern Cook Islands, to investigate vegetation changes on the island, in particular those induced by human impacts. Eight 14C dates of charcoal and higher plant fragment samples indicate that the sediments accumulated since ∼6.0 cal kBP, with an apparent interruption of deposition (hiatus) from 130 to 132 cm in depth, corresponding to ∼2.8 to 0.7 cal kBP. The appearance of Chenopodiaceae pollen from upland weeds, and Cucurbitaceae and Vigna pollen grains from cultivated plants suggest that human influence existed in core sediments above 130 cm in depth. The increased abundance of Pandanus pollen and monolate-type fern spores also implies the existence of human activity.

scholarly journals Vegetation Changes Viewed from Pollen Analysis in Rarotonga, Southern Cook Islands, Eastern Polynesia

Radiocarbon ◽  
2014 ◽  
Vol 56 (02) ◽  
pp. 699-708
Author(s):  
Toshiyuki Fujiki ◽  
Mitsuru Okuno ◽  
Hiroshi Moriwaki ◽  
Toshio Nakamura ◽  
Kei Kawai ◽  
...  
Keyword(s):  
Human Impacts ◽  
Pollen Grains ◽  
Cultivated Plants ◽  
Vegetation Changes ◽  
Human Influence ◽  
Higher Plant ◽  
Radiocarbon Dates ◽  
Cook Islands ◽  
Core Sediments ◽  
Plant Fragment

This study presents accelerator mass spectrometry (AMS) radiocarbon dates and pollen assemblages of 400-cm core sediments collected from the Karekare Swamp in Rarotonga, Southern Cook Islands, to investigate vegetation changes on the island, in particular those induced by human impacts. Eight14C dates of charcoal and higher plant fragment samples indicate that the sediments accumulated since ∼6.0 cal kBP, with an apparent interruption of deposition (hiatus) from 130 to 132 cm in depth, corresponding to ∼2.8 to 0.7 cal kBP. The appearance of Chenopodiaceae pollen from upland weeds, and Cucurbitaceae andVignapollen grains from cultivated plants suggest that human influence existed in core sediments above 130 cm in depth. The increased abundance ofPandanuspollen and monolate-type fern spores also implies the existence of human activity.

Pollen diagrams from interior Labrador

1970 ◽  
Vol 48 (11) ◽  
pp. 1957-1975 ◽  
Author(s):  
Alastair Morrison
Keyword(s):  
Primary Succession ◽  
Vegetation Changes ◽  
Bare Ground ◽  
Radiocarbon Dates ◽  
River Watershed ◽  
Pollen Diagrams ◽  
Glacier Ice ◽  
Lake Waters

Six pollen zones can be distinguished in interior Labrador. The earlier zones represent the primary succession of vegetation from bare ground to boreal woodland or forest, which occupied about 500 years between 5700 and 5200 B.P. There have been only minor fluctuations in the nature of the vegetation since 5200 B.P. Radiocarbon dates show that the zones are contemporaneous over that part of the Lake Plateau within the Churchill River watershed, but similar vegetation changes occurred 1000 years earlier in the Kaniapiskau basin, further north, in New Quebec. These two areas must have been freed of a cover of glacier ice or lake waters immediately before 5700 B.P. and 6700 B.P. respectively.

scholarly journals New Evidence from the East Polynesian Gateway: Substantive and Methodological Results from Aitutaki, Southern Cook Islands

Radiocarbon ◽  
2007 ◽  
Vol 49 (3) ◽  
pp. 1163-1179 ◽  
Author(s):  
Melinda S Allen ◽  
Rod Wallace
Keyword(s):  
New Age ◽  
Tropical Pacific ◽  
Human Settlements ◽  
Radiocarbon Dates ◽  
Cook Islands ◽  
Island Colonization ◽  
Settlement Period ◽  
Biological Evidence ◽  
New Evidence

East Polynesia was the geographic terminus of prehistoric human expansion across the globe and the southern Cook Islands, the first archipelago west of Samoa, a gateway to this region. Fourteen new radiocarbon dates from one of the oldest human settlements in this archipelago, the Ureia site (AIT-10) on Aitutaki Island, now indicate occupation from cal AD 1225–1430 (1σ), nearly 300 yr later than previously suggested. Although now among the most securely dated central East Polynesian sites, the new age estimate for Ureia places it outside the settlement period of either the long or short chronology models. The new dates have, however, led to a comfortable fit with the Ureia biological evidence, which suggests not a virgin landscape, but a highly a modified fauna and flora. The results also provide the first systematic demonstration of inbuilt age in tropical Pacific trees, a finding that may explain widely divergent 14C results from several early East Polynesian sites and has implications for the dating of both island colonization and subsequent intra-island dispersals.

scholarly journals A Radiocarbon Chronology for Human-Induced Environmental Change on Mangaia, Southern Cook Islands, Polynesia

Radiocarbon ◽  
1991 ◽  
Vol 33 (3) ◽  
pp. 317-328 ◽  
Author(s):  
P. V. Kirch ◽  
J. R. Flenley ◽  
D. W. Steadman
Keyword(s):  
Environmental Change ◽  
Anthropogenic Disturbance ◽  
Human Impacts ◽  
Island Ecosystems ◽  
Palynological Analysis ◽  
Cook Islands ◽  
Significant Evidence ◽  
Radiocarbon Chronology ◽  
Age Determinations

A suite of 23 14C age determinations, from a well-stratified rockshelter and from 3 pollen cores on Mangaia Island is reported. The rockshelter has yielded significant evidence for avifaunal extinctions during the period cal. A.D. 1000-1600. The Lake Tiriara pollen cores span a period from ca. 6500 cal. b.p. to the present, and palynological analysis of the TIR 1 core indicates major anthropogenic disturbance on the island's vegetation after ca. 1600 cal. B.P. These sites, and the radiocarbon ages associated with them, provide the first chronologically secure evidence for human impacts on the island ecosystems of the southern Cook Islands.

Vegetation development in the Middle Euphrates and Upper Jazirah (Syria/Turkey) during the Bronze Age

2010 ◽  
Vol 74 (2) ◽  
pp. 216-226 ◽  
Author(s):  
Katleen Deckers ◽  
Hugues Pessin
Keyword(s):  
Bronze Age ◽  
Human Impacts ◽  
Fruit Tree ◽  
Vegetation Changes ◽  
Late Bronze Age ◽  
Climatic Impact ◽  
Vegetation Development ◽  
Local Resources ◽  
Northern Portion ◽  
The Bronze Age

AbstractVegetation changes are reconstructed based on more than 51,000 charcoal fragments of more than 380 samples from nine Bronze Age sites in northern Syria and southern Turkey. In addition to fragment proportions, special attention was paid to the frequency of Pistacia relative to Quercus and Populus/Salix relative to Tamarix, fruit-tree ubiquity, and riverine diversity in order to gain an improved understanding of the human versus climatic impact on the vegetation. The results indicate that human impacts first took place within the riverine forest. This phase was followed by land clearing within the woodland steppe, especially in the northern portion of the study area. In the south near Emar, the woodland steppe probably disappeared by the Late Bronze Age. It is uncertain whether this was caused by aridification and/or human clearing. The northward shift of the Pistacia-woodland steppe is very likely a result of climatic drying that occurred throughout the entire period under investigation. Although increased deforestation is evident through time, the small proportions of imported wood indicate that local resources were still available.

scholarly journals Ancient Maya wetland fields revealed under tropical forest canopy from laser scanning and multiproxy evidence

2019 ◽  
Vol 116 (43) ◽  
pp. 21469-21477 ◽  
Author(s):  
Timothy Beach ◽  
Sheryl Luzzadder-Beach ◽  
Samantha Krause ◽  
Tom Guderjan ◽  
Fred Valdez ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Forest Canopy ◽  
Human Impacts ◽  
Population Expansion ◽  
Farming Systems ◽  
Airborne Lidar ◽  
Ancient Maya ◽  
Large Area ◽  
Radiocarbon Dates ◽  
Field Systems

We report on a large area of ancient Maya wetland field systems in Belize, Central America, based on airborne lidar survey coupled with multiple proxies and radiocarbon dates that reveal ancient field uses and chronology. The lidar survey indicated four main areas of wetland complexes, including the Birds of Paradise wetland field complex that is five times larger than earlier remote and ground survey had indicated, and revealed a previously unknown wetland field complex that is even larger. The field systems date mainly to the Maya Late and Terminal Classic (∼1,400–1,000 y ago), but with evidence from as early as the Late Preclassic (∼1,800 y ago) and as late as the Early Postclassic (∼900 y ago). Previous study showed that these were polycultural systems that grew typical ancient Maya crops including maize, arrowroot, squash, avocado, and other fruits and harvested fauna. The wetland fields were active at a time of population expansion, landscape alteration, and droughts and could have been adaptations to all of these major shifts in Maya civilization. These wetland-farming systems add to the evidence for early and extensive human impacts on the global tropics. Broader evidence suggests a wide distribution of wetland agroecosystems across the Maya Lowlands and Americas, and we hypothesize the increase of atmospheric carbon dioxide and methane from burning, preparing, and maintaining these field systems contributed to the Early Anthropocene.

scholarly journals Systematic Age Gap of Radiocarbon Dates between Organic Bulk Sediment Samples and Fossil Samples of Animal and Plant in Holocene Core Sediments and Their Causes

2016 ◽  
Vol 125 (2) ◽  
pp. 243-256 ◽  
Author(s):  
Daisuke ISHIMURA ◽  
Takahiro MIYAUCHI ◽  
Ryosuke HAYASE ◽  
Keiichi OHARA ◽  
Tsuyoshi YAMAICHI
Keyword(s):  
Bulk Sediment ◽  
Radiocarbon Dates ◽  
Sediment Samples ◽  
Core Sediments ◽  
Age Gap

scholarly journals Radiocarbon Chronology of the Late Pleistocene–Holocene Paleogeographic Events in Lake Baikal Region (Siberia)

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 745-754 ◽  
Author(s):  
Sergey K Krivonogov ◽  
Hikaru Takahara ◽  
Yaroslav V Kuzmin ◽  
Lyobov A Orlova ◽  
A J Timothy Jull ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Lake Baikal ◽  
Baikal Region ◽  
Late Glacial ◽  
Vegetation Changes ◽  
Radiocarbon Dates ◽  
Lake Baikal Region ◽  
Cold Events ◽  
Late Glacial And Holocene ◽  
Radiocarbon Chronology

New radiocarbon dates obtained from Late Pleistocene and Holocene deposits of the southern, eastern, and northern shores of Lake Baikal in 1995–2001 are presented, and the most important results of paleoenvironmental studies based on C data are discussed. The following paleogeographic events were verified with the help of C dating: 1) first Late Pleistocene glaciation (Early Zyryan); 2) Middle Zyryan interstadial; 3) loess formation during the Late Zyryan (Sartan) deglaciation; 4) warm and cold events in the Late Glacial; and 5) vegetation changes and forest successions during the Late Glacial and Holocene.

scholarly journals Changes in Reproductive Traits in Physalis philadelphica; An Unexpected Shift Toward Self-Incompatibility in a Domesticated Annual Fruit Crop

2021 ◽  
Vol 12 ◽  
Author(s):  
Lislie Solís-Montero ◽  
Lorena Aceves-Chong ◽  
Mayumi Vega-Polanco ◽  
Ofelia Vargas-Ponce
Keyword(s):  
Artificial Selection ◽  
Reproductive Strategy ◽  
Evolutionary Process ◽  
Pollen Grains ◽  
Fruit Production ◽  
Wild Plants ◽  
Cultivated Plants ◽  
Self Incompatibility ◽  
Reproductive Parameters ◽  
Crossing Experiment

Domestication is an evolutionary process with an impact on plant reproduction. Many domesticated plants are self-compatible (i.e., they lack mechanisms to reject their own pollen), but few domesticated plants are fully or partially self-incompatible. We used the husk tomato, Physalis philadelphica, as a study model to investigate changes in the reproductive strategy of an annual partially self-incompatible plant during the process of domestication. Wild and cultivated populations of this species coexist in close proximity. These different populations present a high level of morphological and genetic variation associated with different degrees of domestication. We hypothesized that artificial selection favors self-compatibility in cultivated plants through changes in their reproductive strategy and some reproductive parameters associated with domestication. To test this hypothesis, we characterized the floral morphology and some reproductive parameters of weedy plants (wild plants), landraces (semi-domesticated plant), and commercial plants (domesticated plants). We conducted an artificial crossing experiment, germinated the seeds, and recorded seedling growth. Commercial plants had the largest flowers and the highest number of ovules. Yet, they did not differ in other reproductive parameters (e.g., herkogamy, size of pollen grains, stigmatic area, and pollen:ovule ratio) from landraces and weedy plants. Physalis philadelphica produced fruits by autonomous autogamy in the artificial crossing experiment. These fruits were the smallest and lightest fruits at all degrees of domestication; however, fruit set of autonomous autogamy was higher in weedy plants. In addition, fruit production was higher when weedy plants donated pollen to commercial plants. Although seeds produced by autonomous autogamy of weedy plants had a low germination percentage, their cotyledons and the embryonic foliage leaves appeared earlier than in landraces and commercial plants. In conclusion, the domestication syndrome in this plant was manifested as increments in flower size and ovule production. Contrary to expectations, there was higher fruit production by autonomous autogamy in weedy plants than in cultivated plants. It seems that artificial selection in P. philadelphica favors self-incompatibility in cultivated plants. Nonetheless, spontaneous self-pollination seems to be advantageous in weedy populations because they produced viable seeds from which cotyledons and the embryonic foliage leaves emerged earlier than in cultivated plants.

scholarly journals Ecological features of Ambrosia artemisiifolia L. flowers and characteristics of Ambrosia L. pollen seasons in the condition of Lublin (Poland) in the years 2001-2008

2012 ◽  
Vol 61 (2) ◽  
pp. 35-47 ◽  
Author(s):  
Elżbieta Weryszko-Chmielewska ◽  
Krystyna Piotrowska
Keyword(s):  
Airborne Pollen ◽  
Pollen Grains ◽  
Mean Value ◽  
Ambrosia Artemisiifolia ◽  
Cultivated Plants ◽  
Long Distance ◽  
Long Distance Transport ◽  
Ecological Features ◽  
Pollen Seasons ◽  
Male Flowers

In the study, the biology of fl owering of <i>Ambrosia artemisiifolia</i> L. was investigated and the pattern of the <i>Ambrosia</i> pollen seasons in Lublin in the years 2001-2008 was characterised. The structure of male and female <i>A. artemisiifolia</i> flowers was observed in cultivated plants under controlled conditions in the 2000 vegetative season. The number of pollen grains produced by the stamen, flower, inflorescence and plant was determined. It was shown that in <i>A. artemisiifolia</i> flowers nonfunctional pistils occurred with a reduced ovary, performing the role of a pollen presenter. The pistils found in female flowers differed significantly in their morphological features from the pistils in male flowers. It was calculated that one stamrn produced an average of 3 375 pollen grains, whereas one flower 16 875. A plant which produces 20 racemes may release over 420 million pollen grains into the atmosphere. The <i>Ambrosia</i> pollen seasons in particular years had different patterns. In some years, the days of maximum concentration were in the second half of August, in other years in the first half of September. Over the 8-year period, the maximum daily concentration had a mean value of 116 pollen grains in m<sup>3</sup> (31-311). Annual total concentrations of <i>Ambrosia</i> pollen grains ranged between 194 and 1200 grains, and it was 523 grains on the average. The pollen seasons were characterised by the occurrence of several-day-long interruptions in the presence of airborne pollen in the atmosphere of Lublin, which may indicate the long-distance transport of <i>Ambrosia</i> pollen.

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