Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: pollen stratigraphy

Sortuj według:

Ogranicz wyniki do:

Fine-resolution pollen-based evidences of farming and forest development, South-Eastern Estonia

Niinemets E., Saarse L.

Polish Journal of Ecology

2007

Vol. 55, nr 2

283-296

The pollen stratigraphical and lithological data obtained from Lake Lasva, southern Estonia, are summarized. The land-use and vegetation history during the last 6300 years in an agricultural area with dense prehistoric setting is discussed. A high sedimentation rate and laminated structure of lake deposits enabled high-resolution palaeobotanical study of a 985 cm long core. Accelerator mass spectrometry [^14]C dates show good linearity and fit well with varve counts. Up to ca 2900 years BP, birch, pine, spruce and broad-leaved species, later mostly birch, pine and alder, grew in that area. The first weak signs of human impact were traced at 6300 years BP. Human activities were more pronounced be.tween 5400-5100 and 3800-3500 years ago, due to the foundation of Neolithic settlements not far from the lake. The first attempt of small-scale tillage, detected from the first finds of Triticum pollen, followed by a long-term gap, dates back to 5100 years BP. Crop cultivation (Cannabis, Hordeum, Triticum and Secale) became the main means of subsistence not until the Iron Age at about 1600-1400 years ago, but extensive arable farming started to develop 800 years ago, after the German crusaders invaded the area. Pollen dia.grams display several setbacks in arable farming, mostly caused by crop failure due to climate de-terioration and decrease in the population caused by famines, wars and epidemics.

Palinologiczne i diatomologiczne badania osadów interglacjału mazowieckiego z odsłonięcia w kopalni Bełchatów

Balwierz Z., Goździk J., Marciniak B.

Przegląd Geologiczny

2006

Vol. 54, nr 1

61-67

The thickness of Pleistocene deposits in the Kleszczów Graben reach 300 m. Data from these deposits are important for stratigraphic schemes of the Pleistocene of Poland. However, up to now the Mazovian Interglacial deposits were recognized from boreholes only, not from the exposures in the open-cast mine and they comprise incomplete interglacial successions. The present analysis of organic deposits from closed depression exposed on the escarpment of the mine,reveals almost the full pollen succession of the Mazovian Interglacial. The succession started with dominance of birch forest followed by birch-pine and afterwards birch-pine forest with increasing share of alder, spruce and thermophilous trees that led to development of mixed forest which corresponded to climatic interglacial optimum. First there were forests with share of yew which later were replaced by hornbeam and fir. The fir-hornbeam phase closed the climatic optimum. The distinctly colder pine phase following fir-hornbeam phase ended the interglacial succesion of plants in Folwark 93K site. On the basis of changes in diatom composition and relative (percentage) diatom frequency in this site it was determined that the fossil lake sediments represent the diatom succession of the Mazovian Interglacial. The diatom succession from Folwark has been divided into 7 local diatom assemblage zones (LDAZ Fd 1–Fd7). These zones represent four stages of paleolake development and correspond to the local and regional pollen assemblage zones of the Mazovian Interglacial. The Mazovian Interglacial age of the organic deposits from the site Folwark 93K implies the revision of the stratigraphical position of some lithostratigraphic units from the Middle Pleistocene in the Kleszczów Graben. The obtained results indicate also that at least some intensive deformations of the Lower Pleistocene deposits were completed before the Mazovian Interglacial.