Postglacial occurrence and decline of Betula nana L. (dwarf birch) in northeastern Poland

The Late Glacial and Holocene presence of Betula nana L. (dwarf birch) in northeastern Poland was reconstructed through palaeoecological analyses of sediment cores from the Taboły mire located in the territory of the Knyszyńska Forest. Peat records spanning thousands of years were analysed for plant macrofossils along with radiocarbon dating. Betula nana was present in Taboły from ca 13 000 to ca 9000 yr BP. The presence of this species was described in the Late Glacial period, most likely in the Allerød and Younger Dryas. However, our research on the palaeoecology of dwarf birch showed that after the Late Glacial/Holocene transition, the species did not disappear from northeastern Poland and still existed in the Preboreal, Boreal and lower Atlantic periods. The occurrence of Betula nana was documented by the presence of generative remains (nuts and catkin scales) in sediments, which is the best evidence of its in situ position. The later disappearance of the studied species could be related to the negative effects of palaeoenvironmental conditions in the Atlantic, which resulted in a temperature increase and high precipitation, causing the waterlogging of the substratum and rendering it unsuitable for dwarf shrub that prefers severe climate conditions. The Taboły site seems to be one of separate locations of B. nana during the Atlantic in this part of Europe

Development of the Kładkowe Bagno peat-bog in the Late Glacial and Holocene: diversified history of two deposit basins studied with use of macrofossil remains analysis

This pa per pres ents re sults of in ves ti ga tion on peat and la cus trine sedi ments from the K³ad kowe Bagno peat- bog located in the Puszcza Knyszyñska For est. Us ing analy sis of plant re mains from sedi ment sam ples, vege ta tive and gen era tive finds were iden ti fied which al lowed de scrib ing peat units. Bas ing on these re sults, re con struc tion of sub fos silvege ta tion and pa laeoen vi ron men tal changes in the mire was made. Al to gether 4 sub as so cia tions of Sphag ne tum mag -el lan ici were de scribed, which de liv ered in for ma tion about hu mid ity of the mire sur face dur ing peat form ing pro -cesses. Stages of de posit de vel op ment were dated by ra dio car bon method. Ac cu mu la tion of the old est sedi ments in thesouth ern ba sin took place in the Late Gla cial. Peat of the north ern ba sin started to ac cu mu late in the At lan tic pe riod.The both parts of the mire ag gre gated proba bly 400 years ago

Peat decomposition – shaping factors, significance in environmental studies and methods of determination; a literature review

A review of literature data on the degree of peat decomposition – an important parameter that yields data on environmental conditions during the peat-forming process, i.e., humidity of the mire surface, is presented. A decrease in the rate of peat decomposition indicates a rise of the ground water table. In the case of bogs, which receive exclusively atmospheric (meteoric) water, data on changes in the wetness of past mire surfaces could even be treated as data on past climates. Different factors shaping the process of peat decomposition are also discussed, such as humidity of the substratum and climatic conditions, as well as the chemical composition of peat-forming plants. Methods for the determination of the degree of peat decomposition are also outlined, maintaining the division into field and laboratory analyses. Among the latter are methods based on physical and chemical features of peat and microscopic methods. Comparisons of results obtained by different methods can occasionally be difficult, which may be ascribed to different experience of researchers or the chemically undefined nature of many analyses of humification

Eemian and Early Yi stu lian vegetation at Michałowo (NE Poland)

This paper presents the results of palaeobotanical studies (pollen and plant macrofossil analyses) of the sediments from sq the profile Michałowo P-3 (Gródek-Michałowo Depression, NE Poland). At this profile the second bed of peat under Holocene peat and the layer of silts and sands was discovered. The pollen succession indicates that they were deposited, with some gaps, from the beginning of Eernian Interglacial to Early Vistulian. The local pollen zones, distinguished in the pollen diagram, correlate with the regional pollen stratigraphy of the Eemian Interglacial, but the pollen record of hornbeam (ES R PAZ) and spruce (E6 R PAZ) regional zones is absent in Michałowo. In the middle part of the Michałowo pine zone (Mi-5 Pinus L PAZ), a cool oscillation of climate is marked by an opening of forests and development of herb plant communities

Palaeobiodiversity of Knyszyn Forest (NE Poland) Mires Based on the Late Glacial and Holocene Histories of Vascular Plant Species

Peat and lacustrine sediments are a valuable source of knowledge about past biodiversity. Plant macrofossil remains were identified in sediments of mires in northeastern Poland’s Knyszyn Forest. Among them, the remains of species currently absent in this area, such as Potamogeton pusillus, P. friesii, P. filiformis, Myriophyllum alterniflorum, and Cladium mariscus, have been found. In addition, the history of Betula humilis and its possible correlations with another species of bush birch—Betula nana—were of interest. Radiocarbon dating allowed the presence of the studied species to be placed within a time frame, and it was thus established that aquatic species existed in the area under study during the Late Glacial and the turn of the Holocene. Cladium mariscus occurred during the Greenlandian and Meghalayan stages of the Holocene and then became intolerant of habitat changes that occurred. The coexistence of two species of birch known to exist since the Late Glacial was interrupted in the Northgrippian. B. nana, then disappeared from the area, and B. humilis continued to occur as it was more resistant to the changing environmental conditions. It must be emphasized, however, that these conclusions were made possible by the researchers’ access to undisturbed deposits. The mires present in the area of study remain in good condition, providing important and relevant materials for palaeoecological research

The importance of subfossil plant remnants and peat decomposition degree analyses for palaeoenvironment reconstruction

In this article an attempt was made to explain some aspects of palaeoenvironmental studies. Analyses of plant remnants forming peat are the first described problem. There are two kinds of these analyses: carpological method (recognizing of seeds and fruits) and analysis of vegetative tissues. Their connection with description of the phytosociological rules of plant communities, allows to restore successive sequences of local vegetation. Second characterized problem is decomposition degree of peat. That parametr means proportional relation between humus and full peatmass in a peat sample and it is connected with the peatbog surface humidity. Therefore, knowledge of its value supplies information about past humidity and, on ombrotrophic bogs, also about altitude of precipitations (climatic factor)

Phases and interruptions in postglacial development of humic lake margin (Lake Suchar Wielki, NE Poland)

Our study concerns the development of marginal zone of Lake Suchar Wielki (Wigry National Park). This humic lake is characterised by mire occurrence in its marginal zone, covered with a floating mat spreading on water surface. Biogenic sediments (peat archive) present in lakeside allow recognising the thousands years’ development pattern of lake surrounded by mire. The wetland records were analysed for plant macroremains, degree of peat decomposition, sediment geochemical features along with age assessment. Morphological characteristics of the catchment were integrated with the wetland records. Our research showed that after the lake origin in the Allerod, accumulation in its marginal zone was interrupted, which was probably connected with high precipitation in the past. Slope processes could be possible. Stabilisation of environmental conditions took place in the younger Holocene. Despite these perturbations marginal zone of the lake was permanently terrestrial in character, as indicated by values of atomic C:N ratio

Late Glacial and Holocene Vegetation Changes in the Wigry National Park, NE Poland – New Pollen Data from Three Small Dystrophic Lakes

The main phases of the Late Glacial and Holocene development of vegetation in the Wigry National Park were reconstructed based on the pollen analysis of sediments from three small dystrophic lakes (Lake Suchar Wielki, Lake Suchar II and Lake Ślepe). At the current stage of research, the age of the studied deposits was determined by AMS radiocarbon dating of few samples only. This meant that the chronology of the investigated sections had to be estimated also indirectly using their palynological correlation with the radiometrically well-dated section from Lake Wigry. The obtained pollen data confirmed the picture of the postglacial vegetation changes of the Wigry National Park, which was based on earlier studies of Lake Wigry. Furthermore, it documented the existence, mainly in the Preboreal and Atlantic chronozones, of temporary changes in vegetation, which might be a reaction to a short-lived cold fluctuations of climate

Palaeobotanical record of the Eemian Interglacial succession at the Jagodne site (Garwolin Plain, central Poland)

Our high-resolution data of pollen and macrofossils from 2 cores taken from the Jagodne site (Garwolin Plain) reveals a pollen succession covering the final part of the Late Saalian (Marine Isotope Stage MIS 6) and embracing the Eemian (MIS 5e). The results correspond to Regional Pollen Assemblage Zones (RPAZ). The hornbeam phase (E5 RPAZ) has been subdivided into subzones and compared to the corresponding division of the key profile of the Garwolin Plain, Kozłów K2-19. The comparison revealed a considerable sedimentary hiatus in the E5 RPAZ at Jagodne. This is attributed to significant palaeohydrological changes occurring widely in this zone, and also seen at other Eemian sites in Poland. Another specific feature of the Jagodne site is the early, rapid terrestrialisation of the palaeolake and its transformation into a raised bog, which occurred already at the end of the hornbeam phase. The Sphagnum dominated peatbog developed for a long time as evidenced by a thick peat layer covering also the Early Vistulian. Both pollen and plant macrofossil data correspond well to observed lithological boundaries, providing a consistent record of palaeoenvironmental and palaeoclimate changes. The results obtained contribute to knowledge of palaeoenvironmental changes and palaeoclimate interpretation of that area