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Anthropogenic causes of wetland loss and degradation in the lower Kłodnica valley (southern Poland)

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Wójcicki K. J. , Woskowicz-Ślęzak B.

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nr 4

20-29

EN

Loss and degradation of wetlands is now one of the most important environmental issues on a global scale. Previous research based on analyses of cartographic materials allow for quantification of changes in wetland area in recent centuries. The results of lithological research of peat cores, reported in this publication, have established that the processes of anthropogenic loss of wetlands can be much older and in the Kłodnica valley were initiated in the first millennium BC. As a result of increased mineral sedimentation accompanying soil erosion some peatlands have been fossilized whilst the area of others has been reduced. In total, the surface area of peat-forming wetlands in the bottom of the Kłodnica valley decreased by over 60% between the time of the Lusatian Culture settlement and the Middle Ages. Post-peatland habitats are recently used for agricultural or colonized by non-peat forming vegetation. These processes have played a more important role in the degradation of peatland ecosystems than the direct human impact in historic times. Changes in hydrographic networks, land drainage and regulation of water levels in rivers and canals in the last century have contributed to further reducing the wetland areas by almost 50% compared to the 1880s. These processes, however, have mainly affected ephemeral non-peat forming wetlands.

2

Hydrological changes in the lublin polesie during the late glacial and holocene as reflected in the sequences of lacustrine and mire sediments

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Bałaga K.

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tom Vol. 19

37--54

EN

The paleoecological research of biogenic sediments sampled in the different lake-mire ecosystems of the Łęczna-Włodawa Lake District were the basis of studies on hydrological changes during the Late Glacial and Holocene. The lithological differentiation (spatial and temporal) of lacustrine and mire sediments in the studied sites indicates that the hydrological changes were of local nature. The investigations also evidence a specific functioning of the lakes in this region. Lake basins were formed as a result of the ground ice degradation and the transformation of groundwater circulation in the Late Glacial. The total area of lakes in the Lake District was the largest from the Younger Dryas to the Subboreal chronozone. The gradual lowering of water level during the early Holocene resulted in the transformation of sedimentation process, and in the development of typologically differentiated mires and lacustrine-mire complexes.

3

The diversity of fluvial system response to the Holocene hydrological changes using the Vistula River catchment as an example

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Starkel L.

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tom Vol. 77, No 2

193-205

EN

Hydrological changes during the Holocene are expressed in the variable frequency of extreme events and reflected in fluvial sediments and landforms. The diversity of fluvial system response depends on rainfall and runoff-sediment load regime, but is specifically related to the landscape type, size of catchment, and connectivity of valley reaches in the long profile, as well as to increasing human impact. This diversity is exemplified by the Vistula River catchment, investigated in detail during the last decades, providing a basis for demonstrating how various fluvial sequences are expressing palaeohydrological changes. Various types of flood events, ranging from those connected with heavy downpours to continuous rains and to snowmelt floods, play a leading role in catchments of various size and landscape type. Three main models of Holocene transformation of valley floors were distinguished: an incisional one in the mountain headwaters, an aggradational one in low-gradient river valleys, and transitional one reflecting phases of various frequency of extreme events (and their clusters) represented in sequences of cuts and fills. This last transitional type should characterise the middle valley courses, but is best developed slightly upstream on the direct foreland of the Carpathians, where the greatest fluctuations in the river discharge, bed load and suspended load are observed. The presence of many gaps in alluvial sequences requires a better recognition of Holocene hydrological changes and it is recommended to correlate fluvial data with other palaeorecords.

PL

Zmiany hydrologiczne w holocenie wyrażone są w różnej częstotliwości powodzi i zapisane w osadach i formach fluwialnych. Różna reakcja systemu fluwialnego zależy od reżimu opadu, odpływu i transportu rumowiska, które wiążą się z typem krajobrazu, wielkością zlewni, położeniem w profilu podłużnym rzeki, jak i narastającą ingerencją człowieka. Szczegółowe badania dolin dorzecza Wisły w ostatnich dziesięcioleciach stanowiły podstawę określenia, jak różne sekwencje osadów rzecznych odzwierciedlają zmiany paleohydrologiczne. W różnych typach rzeźby i zlewniach różnej wielkości istotną rolę odgrywają lokalne ulewy, albo opady rozlewne lub wezbrania roztopowe. Wyróżniono trzy zasadnicze modele przekształceń den dolin w holocenie: pogłębiania erozyjnego w zlewniach górskich, agradacyjny w dolinach o małym spadku i przejściowy, zapisany w szeregu rozcięć i włożeń, odzwierciedlających fazy o różnej częstotliwości wezbrań. Ten ostatni winien charakteryzować środkowe biegi rzek, ale jest najlepiej rozwinięty na bezpośrednim przedpolu Karpat o największych wahaniach przepływów i transportu rumowiska. Częste występowanie wielu przerw w sekwencjach aluwialnych wymaga spojrzenia całościowego na zmiany hydrologiczne i korelacji środowisk fluwialnych z zapisem zmian w ewolucji szaty roślinnej, osadach jeziornych, stokowych i innych.