|
|
Human impact on the holocene vegetation development in North Macedonia.
Koubský, Karel ; Abraham, Vojtěch (advisor) ; Pokorný, Petr (referee)
This thesis aims to reconstruct the Holocene vegetation development in North Macedonia in relation to human activities; specifically, it focuses on the late Holocene period, when changes in land-use and settlement strategy were simultaneously taking place, which lead to an increased human pressure on the surrounding environment. To describe the vegetation development, a sedimentary profile from a small lake in the Pelister Mountains was chosen for analysis. A total of 25 samples were processed and analysed under a light microscope for the presence of pollen and non-pollen objects. Based on the results of pollen stratigraphy and radiocarbon dating, it was confirmed that the vegetation record covers the entire Holocene period. The early Holocene is characterized by a gradual increase in forest vegetation and a decrease in steppe vegetation. In the middle Holocene, secondary anthropogenic indicators show up in higher numbers. The late Holocene is already showing signs of continuous human presence. Compared to the lowlands, the mountain record shows a rather discontinuous presence of primary indicators, which nevertheless appear after the 5th millennium before present. High percentages of secondary indicators indicate continuous human influence in the mountains. Overall, it has been confirmed that...
|
|
|
The use of modern analogies in the interpretation of paleoecological and archaeobotanical results
Bortelová, Nina ; Novák, Jan (advisor) ; Abraham, Vojtěch (referee)
Standing on the uniformitarian principle, quaternary palaeoecology strives to match fossil proxy data assemblages with their vegetation equivalents in order to understand spatiotemporal ecosystem dynamics. Finding such an equivalent in today's world - a modern analogy of an analyzed fossil sample (or a fossil analogy of a known modern sample, respectively), may represent a highly welcomed helping hand with proxy data interpretation. Nevertheless, one might be skeptical to which extent we can rely on such assumptions in rather specific contemporary state of nature, reflecting f.e. increased CO2 levels, atmospheric nitrogen deposition, habitat fragmentation, or traditional management abandonment. The thesis discusses advantages, difficulties, and some examples of using analogs in quaternary palaeoecology with emphasis on charcoal and pollen analysis since these are the most used in the study of vegetation dynamics over long time scales. It aims to understand and summarize the extent to which modern analogs are helpful with sharpening focus on past landscapes and processes, that formed them into today's state. Keywords: modern analogs, vegetation reconstructions, palynology, anthracology, charcoal, pollen, quaternary palaeoecology
|
|
|
Paleoenvironmental evolution around Lake Ohrid in the context of ancient settlement
Koubský, Karel ; Hošek, Jan (advisor) ; Abraham, Vojtěch (referee)
Lake Ohrid, the oldest lake in Europe, is an ideal place to study the response of the terrestrial ecosystems to many climatic and environmental changes during the Quaternary. It is also a useful source of information regarding the interactions between man and environment during the Holocene - this applies especially to the Late Bronze Age period and the beginning of the Iron Age, when there were profound changes in landscape management and when lakeside settlements were suddenly abandoned, which is also evident in the palaeobotanical record. This work summarizes the existing knowledge on this issue and presents various possibilities for studying paleoenvironmental development in this area. Key words: Holocene - Lake Ohrid - paleoenvironmental reconstruction - settlement - Bronze Age
|
|
|
Palynological synthesis for the Czech Republic
Abraham, Vojtěch
The aim is to gather pollen sequences and derive from them synthetic information on past species distribution and Holocene vegetation history. Lonicera nigra was selected as a model taxa. The phylogeographic hypothesis that its Alpine and Carpathian populations survived the LGM in separate refugia is supported only by the Late-Glacial record. This shrub migrated rapidly from southern to central Europe during the warm oscilations of the Late Glacial. The synthesis of vegetation history was produced by applying the REVEALS model, which can filter out following factors influencing the relationship between pollen and vegetation: pollen taphonomy, pollen productivity and pollen dispersal. It was necessary to calculate and test those parameters, so the goals were partly methodical. Pollen productivity estimates are calculated within the Relevant Source Area of Pollen, which is influenced by vegetation structure. Subsequent validation of those values in the area of the REVEALS model 10000 km2 and selection of additional values for lacking taxa created the best set of parameters for the study area. The source fossil dataset for purposes of this synthesis is the newly developed Czech Quaternary Pollen database (PALYCZ). Non-direct multivariate analysis of pollen percentages including all taxa revealed a similarity...
|
|
|
Primary Succession - study methods and pollen analysis opportunities
Suk, Pavel ; Abraham, Vojtěch (advisor) ; Prach, Jindřich (referee)
This thesis focuses on the main study methods of primary succession. It compares their advantages and disadvantages, the scales of usage and the outputs they bring. Due to the duration of a succession development (in hundreds of years), indirect approach - space-for- time substitution using chronosequences (sites that differ only in age and make up succession series) is often used instead of direct study methods. Breach of the the critical assumption that all sites follow the same trajectory may lead to false conclusions about the successional development. This thesis presents examples showing this problem, ways to prevent it and offers an alternative method - pollen analysis. Pollen analysis is on average used for larger spatial and temporal scales but partially overlaps scales of space-for-time substitution. The thesis presents biases of pollen analysis and ways how to solve/limit them and introduces abandoned, partially flooded quarries as a suitable environment for the use of this method to study succession inferred from rapidly growing limnic sediment.
|
|
| |
|
|
Long-term dynamics of Norway spruce (Picea abies) in relation to disturbances
Rayová, Světlana ; Kuneš, Petr (advisor) ; Abraham, Vojtěch (referee)
This thesis summarizes the basic knowledge about the dynamics of spruce forests in Europe on Holocene scale. It presents an overview of glacial refugia during the last glacial maximum and migration routes of spruce expansion to Europe. It also presents the basic facts about disturbancy dynamics and differences in disturbancy dynamics of northern and central Europe. In the last part, I have listed the basic palaeoecological methods that help in the study of spruce disturbances. Keywords: Norway spruce, Holocene, disturbance, dynamics, paleoecological methods
|
|
|
Relative pollen productivity estimates of main tree taxa of Central Europe in model area Křivoklátsko.
Fořtová, Pavlína ; Abraham, Vojtěch (advisor) ; Roleček, Jan (referee)
Pollen spectra found in sediments enable the research of quantitative changes in vegetation composition in the past. The fact is conditioned upon assumption of unchangeable linear relationship between abundance of pollen and the vegetation that is responsible for its production. Calibration of this relationship is experimentally performed on modern pollen samples and current vegetation. Relative pollen produktivity etimates (PPEs) represents basic parameters for the conversion of proportional pollen data into the vegetational ones. Their knowledge is indispensible for the quantitative vegetation restoration and for the simulating of the processes of pollen dispersion and deposition. PPEs estimation is performed by ERV model which corrects nonlinear relationship of proportional pollen and vegetation data back to the linear relationship. ERV model estimates PPEs values together with values of pollen background by maximum likelihood method. Knowledge of PPEs of main tree species is crucial for the understanding of processes which takes place on the level of landscape scale. Model area of Křivoklátsko was selected due to its high forest coverage and tree diversity. Twenty-four localities were chosen upon stratified random selection. Moss polsters containing modern pollen loading were taken and detailed...
|
|
|
Palynological synthesis for the Czech Republic
Abraham, Vojtěch
The aim is to gather pollen sequences and derive from them synthetic information on past species distribution and Holocene vegetation history. Lonicera nigra was selected as a model taxa. The phylogeographic hypothesis that its Alpine and Carpathian populations survived the LGM in separate refugia is supported only by the Late-Glacial record. This shrub migrated rapidly from southern to central Europe during the warm oscilations of the Late Glacial. The synthesis of vegetation history was produced by applying the REVEALS model, which can filter out following factors influencing the relationship between pollen and vegetation: pollen taphonomy, pollen productivity and pollen dispersal. It was necessary to calculate and test those parameters, so the goals were partly methodical. Pollen productivity estimates are calculated within the Relevant Source Area of Pollen, which is influenced by vegetation structure. Subsequent validation of those values in the area of the REVEALS model 10000 km2 and selection of additional values for lacking taxa created the best set of parameters for the study area. The source fossil dataset for purposes of this synthesis is the newly developed Czech Quaternary Pollen database (PALYCZ). Non-direct multivariate analysis of pollen percentages including all taxa revealed a similarity...
|
|
|
Palynological synthesis for the Czech Republic
Abraham, Vojtěch ; Pokorný, Petr (advisor) ; Chytrý, Milan (referee) ; Sugita, Shinya (referee)
The aim is to gather pollen sequences and derive from them synthetic information on past species distribution and Holocene vegetation history. Lonicera nigra was selected as a model taxa. The phylogeographic hypothesis that its Alpine and Carpathian populations survived the LGM in separate refugia is supported only by the Late-Glacial record. This shrub migrated rapidly from southern to central Europe during the warm oscilations of the Late Glacial. The synthesis of vegetation history was produced by applying the REVEALS model, which can filter out following factors influencing the relationship between pollen and vegetation: pollen taphonomy, pollen productivity and pollen dispersal. It was necessary to calculate and test those parameters, so the goals were partly methodical. Pollen productivity estimates are calculated within the Relevant Source Area of Pollen, which is influenced by vegetation structure. Subsequent validation of those values in the area of the REVEALS model 10000 km2 and selection of additional values for lacking taxa created the best set of parameters for the study area. The source fossil dataset for purposes of this synthesis is the newly developed Czech Quaternary Pollen database (PALYCZ). Non-direct multivariate analysis of pollen percentages including all taxa revealed a similarity...
|
guest ::
RSS feed.