Stanowisko flory interglacjału eemskiego w Warszawie przy ul. Kasprzaka

Abstract

 W obrębie drobnoziarnistych piasków zastoiskowych (głęb. 4,5-10,2 m), leżących na glinie zwałowej zlodowacenia środkowopolskiego, stwierdzono w Warszawie przy ul. Kasprzaka serię sprasowanych

torfów o miąższości 1,5-1,8 m. Wyniki badań palinologicznych tej serii pozwoliły prześledzić historię rozwoju flory od fitofazy d do i podziału biostratygraficznego interglacjału eemskiego według K. Jessena, V. Milthersa (1928). Wiek przykrywających torfy piasków z glęb. 4,6-5,0 m określono metodą TL na ok. 60 tys. lat B P. Są one więc starsze od głównego stadiału ostatniego zlodowacenia (wisły).

SITE OF EEMIAN INTERGLACIAL FLORA IN WARSAW, KASPRZAK STREET

In Warsaw at junction of Kasprzak and Karolkowa streets there are at depth of 4.5-10.2 m fine- grained ice-dam Pleistocene sands covered by anthropogenic soils, 1.3-2.7 m thick. Inside these sands there are compressed peats, 1.5-1.8 m thick, locally underlain by lake sediments (gyttja). Beneath these sands there is a till, noted to a depth of 12 m (bottom is unknown). The top surface of this till forms in many cases a substrate of interglacial organic sediments in this part of the town. It is quite uneven and indicates considerable altitude differences, reflecting a lacustrine landscape of this area during the Eemian Interglacial.

Comparison and analysis of boreholes for a larger area (Fig. 1) prove that palynologicaly studied organic sediments come from deposition within a valley or another field depression that forms a buried branch of ancient large water reservoir in the neighbourhood. Two reservoirs could have also existed in this area. Sediments which were palynologicaly studied by J. Raniecka-Bobrowska (1954) and Z. Borówko-Dłużakowa (1960) come from these reservoirs. In this part of the town, sands of the Eemian Interglacial age were found to contain at Leszno Street (Fig. 1) bone remains of a fossil elephant Elephas intiquus Falc. et Cout. (K. Krysiak, 1962; M.D. Domosławska-Baraniecka, S. Gadomska, 1965).

Development of the flora described from sediments of the section at Kasprzak Street 1/72 is presented on the basis of a classic scheme of a biostratigraphic subdivision of the Eemian Interglacial as proposed by K. Jessen, V. Milthers (1928). It comprises the phytophases from d to i of this subdivision.

The phytophase d and the older ones have not been completely found within sandy and sandy-silty sediments with organic matter. The first, older part is predominated by Betula with abundant

NAP, open areas inclusive (Hippophae, Helianthemum, Saxifraga, Polygonum bistorta/viviparum, Ephedra distachya type, Gentiana, Sanguisorba officinalis, Chamaenerion/Epilobium, Selaginella selaginoides.

The second, younger part is predominated by Pinus. Considerable participation is noted by Salix. Secondary deposit sporomorphs of pre-Quaternary plants and specimens of Hystricosphaeridium are also numerous in pollen spectra. Non-decalcified (by soil processes) substrate favored abundant occurrence in the area of the present Warsaw town and particularly its northwestern part of Hippophae (K.M. Krupinski, 1980).

Since the beginning of the phytophase e the unidirectional trend for climatic transformation is noted, making development of plants of coniferous cool climate forests, mixed temperate climate forests and rich multi-species deciduous forests. Pollen spectra contain only Quaternary specimens. Ulmus,

Fraxinus and Quercus appeared and reached considerable contents, the same as Alnus and at the end also Corylus. In the final phase of this phytophase the plants of slightly higher thermic demands were noted: Hedera, Viscum, Humulus, Salvinia. The phytophase f indicates a distinct tripartity. The subphytophase f-l is predominated by Corylus, abundant Quercus, curve rise of Tilia and Taxus. The subphytophase f- 2 is predominated by Corylus, numerous Tilia and Quercus, and rising Alnus and Carpinus.

The subphytophase f-3 indicates a varying quantitative content of Corylus and Carpinus, slight drop of curves of Tilia and Taxus, further rise of Alnus, appearance of the empiric curve of Picea and end of still numerous Fraxinus and Ulmus. Within this phytophase there are sporomorphs of Ilex.

Amongst the trees of the phytophase g there is predominant Carpinus, at first with still numerous

Corylus and Tilia (subphytophase g-l), then with rare but quickly rising Abies, significant Picea (subphytophase g-2) and at the end with numerous Abies, Picea and Alnus (subphytophase g-3). In the first part of this phytophase the climate was warm, wet and mild (appearance of Buxus). From a point of view of contents of the phytophase g this section belongs to the Eemian floras that indicated very early appearance of Carpinus pollen grains in pollen spectra. Participation of the latter in pollen spectra usually exceeds 50%, similarly as in the section Warsaw-Żoliborz (J. Raniecka-Bobrowska, 1954), Horoszki (K. Bitner, 1954), Sławno (S. Tołpa, 1961), Józefów (M. Sobolewska, 1966), Główczyn (J. Niklewski, 1968), Aleksandrów, Faustynów, Rogów (Z. Janczyk-Kopikowa, 1973, 1985), Karczunek (K.M. Krupiński et al., 1982), Zgierz-Rudunki (M. Jastrzębska-Mamelka, 1985), Komorów (K.M. Krupiński, 1986), Komorów, Warsaw-Wawrzyszew, Lomżyca Basin (K.M. Krupiński, in press).

The phytophase h can be divided into three subphytophases: h-J with Picea-Abies communities accompanied by numerous Carpinus, h-2 with Abies, Picea and rare Carpinus, and h-3 with Picea and Abies, accompanied by sporadic Carpinus, quickly rising Pinus and Betula, and distinctly falling Alnus.

Participation of Picea in pollen spectra of the phytophase h of this section is high (maximum 38%), independently on location of the Warsaw area at present outside the geographic extent of this tree (W. Szafer, 1959, 1964; A. Środoń, 1967). A conclusion is to be drawn therefore that climatic-ecologic conditions of Warsaw during this phytophase of the Eemian Interglacial have been more favourable for development of Picea than now. Abies was also more numerous in this area (A. Środoń, M. Gołąbowa, 1956; A. Abramowicz, 1952; C. Pacyniak, 1964).

Distinct climatic cooling of the phytophase i was reflected by further decrease of trees with greater climatic demands. At first compact forest pine-spruce communities of boreal type were gradually more scattered, reflecting distinct cooling of the climate. Selaginella selaginoides, Polemonium and Gentiana appeared.

Sediments of younger phytophases of this interglacial and the post-interglacial period have not been preserved. Top of studied sediments is very sharp and of erosive origin.

The succession row: Betula, Pinus, Ulmus, Fraxinus, Quercus, Alnus, Corylus, Tilia, Carpinus, Picea,

Abies, Pinus, Betula contents of individual taxons and presence of characteristic floristic elements speak for the Eemian age of flora from this site. It indicates numerous quantitative and qualitative similarities to floras of the Eemian Interglacial age, coming from other sites of this part of Poland.

Thermoluminescence datings of sands from the upper part of the section (depth 4.6-5.0 m) introduce the age of about 60 ka and therefore indicate the interval that preceded the main stage of the last (Wisła) glaciation.