scholarly journals Palaeobotanical evidence for warm summers in the East Siberian Arctic during the last cold stage

2005 ◽  
Vol 63 (3) ◽  
pp. 283-300 ◽  
Author(s):  
Frank Kienast ◽  
Lutz Schirrmeister ◽  
Christine Siegert ◽  
Pavel Tarasov
Keyword(s):  
Sediment Accumulation ◽  
Food Resource ◽  
Floristic Composition ◽  
Plant Macrofossils ◽  
Arctic Vegetation ◽  
Cold Stage ◽  
Plant Remains ◽  
Siberian Arctic ◽  
Large Populations ◽  
Steppe Communities

Plant macrofossils from the “Mamontovy Khayata” permafrost sequence (71°60′N, 129°25′E) on the Bykovsky Peninsula reflect climate and plant biodiversity in west Beringia during the last cold stage. 70 AMS and 20 conventional14C dates suggest sediment accumulation between about 60,000 and 750014C yr B.P. The plant remains prove that during the last cold-stage arctic species (Minuartia arctica,Drabaspp.,Kobresia myosuroides) coexisted with aquatic (Potamogeton vaginatus,Callitriche hermaphroditica), littoral (Ranunculus reptans,Rumex maritimus), meadow (Hordeum brevisubulatum,Puccinellia tenuiflora) and steppe taxa (Alyssum obovatum,Silene repens,Koeleria cristata,Linum perenne). The reconstructed vegetation composition is similar to modern vegetation mosaics in central and northeast Yakutian relict steppe areas. Thus, productive meadow and steppe communities played an important role in the Siberian Arctic vegetation during the late Pleistocene and could have served as food resource for large populations of herbivores. The floristic composition reflects an extremely continental, arid climate with winters colder and summers distinctly warmer than at present. Holocene macrofossil assemblages indicate a successive paludification possibly connected with marine transgression, increased oceanic influence and atmospheric humidity. Although some steppe taxa were still present in the early Holocene, they disappeared completely before ∼290014C yr B.P.

Effects of food, kinship, and density on the longevity of spiderlings

2021 ◽  
pp. 741-751
Author(s):  
Marta Luciane Fischer ◽  
Lays Cherobim Parolin ◽  
Felipe Marcel Neves ◽  
German Antonio Villanueva-Bonilla ◽  
João Vasconellos-Neto
Keyword(s):  
Population Density ◽  
Laboratory Experiments ◽  
Survival Rates ◽  
Food Resource ◽  
Behavioral Characteristic ◽  
Risk Of Predation ◽  
Large Populations ◽  
Main Factors ◽  
Conspecific Tolerance ◽  
Loxosceles Laeta

Cannibalism is a behavioral characteristic found in a wide variety of animal groups. Although the rates of cannibalism can vary from one group to another, studies indicate that the main factors contributing to an increase in the frequency of such behavior are the availability of food, population density, the behavior and availability of victims, and environmental stress. We carried out different laboratory experiments to assess whether different factors such as the presence or absence of food among siblings and non-siblings, and at different densities among conspecific and heterospecific individuals, affect longevity of recently emerged Brazilian brown recluse (Loxosceles intermedia Mello-Leitão, 1934) and Chilean recluse (Loxosceles laeta (Nicolet, 1849)) spiderlings during periods of starvation. The results revealed that the survivorship of L. laeta during starvation was significantly higher than that of L. intermedia and that the addition of conspecific individuals increased survival rates by 1.5- and 1.6-fold, respectively. The tolerance of conspecifics differed between the two species, and generally, cannibalism was not observed, probably due to the risk of predation and limited consumption by weakened spiders, which coincided with the continued availability of endogenous vitelline reserves, thus indicating that the use of these spiderlings as a food resource may act to regulate starvation in more resistant spiders. The greater longevity and conspecific tolerance of L. laeta may be important factors contributing to the establishment of large populations of this spider in restricted areas, whereas for L. intermedia, hunger probably functions as a trigger for dispersal.

scholarly journals XIII.—The Plant Remains in the Scottish Peat Mosses

1907 ◽  
Vol 45 (2) ◽  
pp. 335-360 ◽  
Author(s):  
Francis J. Lewis
Keyword(s):  
Salient Feature ◽  
The South ◽  
Scottish Highlands ◽  
Arctic Vegetation ◽  
Arctic Plants ◽  
Plant Remains ◽  
Low Levels ◽  
Made In

An investigation of the peat mosses in some districts of the Scottish Highlands was made in 1905, with a view of comparing the features found there with those already recorded from the Southern Uplands in 1904. The salient feature met with in the Southern districts was the existence in all the older mosses of an upper and lower forest-bed, with a zone of Arctic plants intercalated between. The existence of this Arctic plant bed, stretching at the same horizon through the peat in districts widely separated, indicates a lowering of temperature which must have obtained over much greater areas; for the conditions implied by the presence of an Arctic vegetation at low levels in the South of Scotland would suffice—precipitation being great enough—to produce glaciation in the Highlands.

Influences of Holocene climate and water levels on vegetation dynamics of a lakeside wetland

1996 ◽  
Vol 74 (10) ◽  
pp. 1602-1615 ◽  
Author(s):  
Zicheng Yu ◽  
J. H. McAndrews ◽  
D. Siddiqi
Keyword(s):  
Developmental Stages ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
Plant Macrofossils ◽  
Water Levels ◽  
Taxon Richness ◽  
Holocene Climate ◽  
Wetland Development ◽  
Stage 1 ◽  
Time Substitution

Sediment lithology, pollen, and plant-macrofossil data from the Paynter Site, southern Ontario, revealed three wetland developmental stages during the past 11 000 years: (i) a Carex, Eupatorium, and Eleocharis dominated marsh with some Larix, Abies, and Picea (ca. 11 000–8300 cal years BP); (ii) a Verbena hastata and Mentha arvensis marsh (ca. 8300–7460 cal years BP); and (iii) a white cedar (Thuja occidentalis) swamp (7460 cal years BP to present). There were no significant successional changes in the initial diverse marsh (stage 1) for about 2700 years; its high taxon richness was maintained by fluctuating water levels. The succession from marsh to swamp at 7460 cal years BP was caused by mid-Holocene warm and dry climate, which corresponded with cedar expansion elsewhere in Ontario. The swamp peat record was interrupted at ca. 6400 cal years BP by declining water levels, culminating in a dry period, as indicated by a sandy layer, rare macrofossils, and a low sediment-accumulation rate (0.012 cm/year). The reappearance of cedar swamp macrofossils since 3200 cal years BP corresponded with the recovery of water levels owing to a more humid late Holocene climate and flooding from isostatic tilt. Human disturbance such as damming and logging caused the development of historical cedar and thicket swamps with abundant Alnus rugosa and weedy taxa. This sequence of wetland development did not match the present vegetational gradients from Carex–Typha herb marsh, through Myrica–Decodon shrub marsh and Alnus–Fraxinus thicket, to Thuja swamp. At this site, the wetland development was mainly influenced by allogenic factors such as water levels and climate rather than autogenic factors. Keywords: wetland succession, climate change, hydrological change, Holocene, paleoecology, disturbance, space-for-time substitution, plant macrofossils, Thuja expansion, Ontario.

The Hoxnian Interglacial deposits at Woodston, Peterborough

1992 ◽  
Vol 338 (1284) ◽  
pp. 131-164 ◽  
Keyword(s):  
Sedimentary Environment ◽  
Plant Macrofossils ◽  
Estuarine Environment ◽  
Middle Pleistocene ◽  
Marine Transgression ◽  
South Side ◽  
Broad Agreement ◽  
Plant Remains ◽  
Closed Canopy ◽  
The Individual

Interglacial deposits on the south side of Peterborough have yielded a diverse flora and fauna which lived in an estuarine environment that was affected by marine transgression and regression. Fossils described from six sequences indicate that the deposits accumulated under fully temperate conditions. The Woodston Beds have a diversity of fossils (pollen, plant macrofossils, molluscs, ostracods, insects and mammals) which allows their palaeoecological relationships to be examined, and compared with those of other sites of similar age. The environmental reconstructions based on the individual taxa, although emphasising differing facets of the habitat, are in broad agreement. Some slight discrepancies arise from the assumption that the organisms are characteristic of the sedimentary environment in which they are found. In fact many of the fossils have been transported to the site of deposition from nearby habitats. Evidence of a closed canopy forest with associated land environments, is provided by the plant remains and the land molluscs, and to a lesser extent by the insects and the mammals. A large, slow- flowing river, with adjacent marsh and meadow areas is also suggested by the taxa of molluscs, ostracods and insects present. Molluscs and ostracods show clearly the presence of marine influences between 11 and 14 m Ordnance Datum . The climate under which the Woodston Beds were deposited was slightly warmer than the present. An age in the Hoxnian Interglacial of the Middle Pleistocene is proposed.

scholarly journals Community Sporobolus Cryptandrus (Torr.) A. Gray in the Northern Part of Volga-Akhtuba Floodplain

2018 ◽  
pp. 5-14
Author(s):  
Mikhail Maltsev ◽  
Vadim Sagalaev
Keyword(s):  
Plant Communities ◽  
Early Stage ◽  
Floristic Composition ◽  
Summer Period ◽  
Short Term ◽  
River Bed ◽  
Volgograd Region ◽  
Cereal Species ◽  
Steppe Communities ◽  
Sporobolus Cryptandrus

On the territory of the Volga-Akhtuba floodplain, plant communities including Sporobolus cryptandrus are found. This is an adventitious species from North America that came to Europe in the early 20th century. In Russia, Sporobolus cryptandrus was first discovered in 1998 on the territory of the Volgograd region. Currently, Sporobolus cryptandrus is actively distributed throughout the Volgograd regions. Probably, Sporobolus cryptandrus was introduced together with imported grain and mixed fodders. This species was originally built into the plant communities of sandy steppes. In this paper, we describe the S. cryptandrus communities that we found in the Volga-Akhtuba floodplain. The descriptions were carried out at two sites in the northern part of the floodplain. Geobotanical sites are located on the nearbed sand banks along the river bed. Akhtuba. Completed 19 geobotanical descriptions. All descriptions were accumulated in an electronic database based on the TURBOVEG program. Communities of Sporobolus cryptandrus are characterized by poor floristic composition, low overall projective cover. Habitats of communities are subject to short-term flooding in the spring-summer period, as well as cattle grazing. In communities dominated: Sporobolus cryptandrus, Secale sylvestre, Artemisia marschalliana. We assume that these phytocenoses can be classified as cl. Artemisietea tchernievianae Golub 1994. Sporobolus cryptandrus has shown itself as an agriophyte and a transformer species that can completely replace the dominant cereal species in sand steppe communities or be introduced to pioneer communities at an early stage of overgrowth. Settling of this adventive species can lead to the loss of the natural appearance of the vegetation of sandy substrates. Propagation processes need further observation and analysis.

scholarly journals Geographical distribution, habitats and modern state of Carlina cirsioides (Asteraceae) populations

2021 ◽  
Vol 29 (1) ◽  
pp. 17-27
Author(s):  
V. I. Melnyk ◽  
I. O. Kovalchuk ◽  
L. I. Dovhopola ◽  
Y. P. Shapran
Keyword(s):  
Central Europe ◽  
Floristic Composition ◽  
Systematic Position ◽  
Modern State ◽  
Separate Species ◽  
North East ◽  
The North ◽  
Herbaceous Communities ◽  
Steppe Communities ◽  
Relic Species

The study of the current state and habitats of rare and threatened species of plants is a relevant task of ecological research. The paper presents the results of the study of systematic position, habitats and modern state of populations of a rare species included in the Red DataBook of Ukraine Carlina cirsioides Klokov (=C. acaulis L.). Carlina cirsioides is well-known to European phytosozologists as an endemic and relic species of the Flora of Ukraine. At the same time, the species independence of this taxon is not recognized by the authors of monographs on the Carlina genus and by the authors of “Flora Europaea”. Comparative morphological, chorological and ecological-coenotic analyses do not give sufficient reasons to consider C. cirsioides described by Klokov as a separate species, endemic and relic species of the Flora of Ukraine. According to the morphological traits, the specimens from the lowland part of Ukraine belong to the C. acaulis caulescens subspecies, which is distributed mostly in the lowlaand regions of Europe. Ecological-coenotic conditions of habitats of C. acaulis in the plains of Ukraine are different from those in the mountain regions and are close to the plains habitats of this species in Central Europe. Steppe communities of class Festuco-Brometea, of which C. acaulis is component in the plains part of Ukraine, are close to xerothermic herbaceous communities of Central Europe; forest communities of Erico-Pinetea with C. cirsioides in Ukrainian Polissia and the North-East Poland are very сlose by floristic composition. The removal of separate species status of the plains populations of C. acaulis near the eastern border of the range does not at all downplay its sozological significance. Taking into account the low number of C. acaulis in the Volhynian-Podolian Upland and in the Polesian Lowland, all localities of this species in the lowland part of the range in Ukraine must be taken under protection in situ.

Systematic composition and evolutionary significance of floristic assemblage of the Toptan Formation (Lower Cretaceous, North-East of Russia)

Palaeobotany ◽  
2017 ◽  
Vol 8 ◽  
pp. 28-44 ◽  
Author(s):  
L. B. Golovneva ◽  
S. V. Shczepetov ◽  
A. E. Livach
Keyword(s):  
Main Part ◽  
Floral Development ◽  
Floristic Composition ◽  
Flowering Plants ◽  
Evolutionary Significance ◽  
North East ◽  
The North ◽  
Magadan Region ◽  
Plant Remains ◽  
Systematic Composition

The analysis of the distribution of plant remains in deposits of the Aigur and Toptan formations (Omsukchan district of the Magadan Region) showed that the main part of the species that were included in the Toptan stratoflora (Samylina, 1976), in fact come from the Aigur Formation. Floristic assemblages of the Aigur and Toptan formations are very similar in systematic composition. Increasing the diversity of flowering plants and reduction of typical Cretaceous taxa (cycadophytes and Ginkgoales was not indicated on the boundary between these formation. Thus, there is no evidence of significant changes in the floristic composition at this stratigraphic level and the existence of independent Toptanian stage in the evolution of the mid-Cretaceous flora of the North-East of Russia. Floristic assemblages from the Galimyi, Aigur and Toptan formations are proposed to be merged into a single Sugoi flora, which should be attributed to the Buor-Kemus stage of floral development (lower-middle Albian). The description of the lectostratotype of the Toptan Formation is first published and distribution of this formation is illustrated.

Late Glacial and Postglacial Pollen and Plant Macrofossils from Lake West Okoboji, Northwestern Iowa

1979 ◽  
Vol 12 (3) ◽  
pp. 358-380 ◽  
Author(s):  
Kent Van Zant
Keyword(s):  
Lake Level ◽  
Deciduous Forest ◽  
Accumulation Rate ◽  
Coniferous Forest ◽  
Sediment Accumulation ◽  
Late Glacial ◽  
Plant Macrofossils ◽  
Pollen Influx ◽  
Pine Trees ◽  
Wet Ground

Pollen and plant macrofossils preserved in lake sediment from Lake West Okoboji, Dickinson County, Iowa, indicate how the vegetation of that area changed during the late glacial and postglacial. A closed coniferous forest, dominated by spruce and larch trees, produced the Picea-Larix pollen assemblage zone. Fir trees were a minor constituent of this forest; pine trees were probably absent. Black ash trees increased in abundance at Lake West Okoboji and by 13,500 yr ago were an important constituent of the forest. The sediment accumulation rate and the pollen influx were low throughout this time. Birch and alder pollen peaked in abundance approximately 11,800 yr ago. Pollen influx increased rapidly as birch and alder replaced coniferous trees on the uplands. A deciduous forest, containing abundant oak and elm trees, replaced the birch-alder-coniferous forest. This forest inhabited northwestern Iowa from approximately 11,000 to 9000 yr B.P. Nonarboreal species became prevalent between approximately 9000 and 7700 yr B.P. as prairie began to replace deciduous forest on the uplands. Charred remains of Amorpha canescens and other upland species attest to the presence of prairie fires as an aid in establishing prairie and destroying the forest. The pollen influx declined. The warmest, driest part of the postglacial occurred in northwestern Iowa from approximately 7700 to 3200 yr ago. Lake level fell 9 to 10 m, and prairie extended to the edge of the lake. Wet-ground weeds inhabited areas near lake level which were alternately flooded, then dry. Pollen influx was approximately 100 grains/cm2/yr during the driest time in this dry interval.Deciduous trees, particularly oaks, returned after approximately 3200 yr B.P. Prairie continued to occupy the uplands but trees were more common in the lowlying wet areas. Settlement by Europeans in northwestern Iowa about 1865 is marked by an increase in weed pollen. Macrofossil deposition changed in 1910 in response to the stabilization of lake level.

scholarly journals Miocene carpological floras of the Konin region (Central Poland)

2017 ◽  
Vol 57 (1) ◽  
pp. 39-100 ◽  
Author(s):  
Rafał Kowalski
Keyword(s):  
Plant Communities ◽  
Brown Coal ◽  
Floristic Composition ◽  
Open Pit ◽  
Raised Bog ◽  
Open Pit Mines ◽  
Zonal Vegetation ◽  
Plant Remains ◽  
First Time ◽  
Warm Temperate

AbstractCarbonaceous, three-dimensionally preserved macroscopic plant remains from the Lubstów, Gosławice and Pątnów brown coal open-pit mines are described and illustrated, providing a comprehensive elaboration of the middle Miocene carpological floras of the Konin region. The diaspores represent the following families: Pinaceae, Sciadopityaceae, Cupressaceae, Annonaceae, Cabombaceae, Nymphaeaceae, Araceae, Typhaceae, Cyperaceae, Vitaceae, Rosaceae, Rhamnaceae, Fagaceae, Myricaceae, Cornaceae, Nyssaceae, Symplocaceae, Ericaceae, Araliaceae, and Adoxaceae. Forty-two species were recognised or documented for the first time in the Konin region. Two genera, three species and three morphotypes are described as new taxa.Most of these plant remains represent azonal vegetation. Ericaceous bogs, pine bogs and mixed coniferous bogs, accompanied byGyptostrobusswamp forests and various aquatic plant communities, are suggested as the most widespread vegetation types. Remains representing mesophytic, zonal vegetation, resembling extant evergreen broad-leaved and mixed mesophytic forests, are sparse. ASciadopitysraised bog, a mixed coniferous bog subtype, was one of the important biomass sources forming the brown coal of the I-Middle Polish seam group. Other bog types recognised in Lubstów presumably also played a part in this process. Wildfire is suggested as an important factor controlling the Miocene vegetation of the Konin region.The floristic composition and lithostratigraphy indicate the Badenian age (16.3–12.8 Ma) for the studied floras, but radiometric data suggest that two Lubstów floras are older and one is younger than 13.6 Ma. Biostrati-graphically, Lubstów floras were correlated with the Klettwitz – Salzhausen floristic complex. Based on several climatic indicators and biostratigraphic correlation, the climate is estimated to have been humid, warm-temperate or subtropical.The upper Miocene lower Rhenish Basin floras are the most comparable in floristic and plant communities’ composition. Tropical – subtropical, Mediterranean and extinct genera represent approximately 40% of the genera identified in Lubstów.

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