ItemZmienność termicznych pór roku w Poznaniu(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Szyga-Pluta, KatarzynaOn the basis of period 1921–2008 series of monthly values of air temperature in Poznań the eight thermal seasons were characterized. The duration of thermal season was determined in relation to the day, when the air temperature crossed the following thermal thresholds: 0, 5, 10 and 15°C. Considering the values of the mean air temperature there were defined the following thermal seasons: early spring (0,0–4,9°C), spring (5,0–9,9°C), early summer (10,0–14,9°C), summer (above 15,0°C), early autumn (10,0–14,9°C), autumn (5,0–9,9°C), early winter (0,0–4,9°C) and winter (below 0,0°C). Gumiński method was applied to estimate the first and the last days and the duration of thermal periods mentioned above. It has been stated that in the analyzed period the highest range of the beginning was characteristic for early spring (Tab. 1). The lowest range characterizes the thermal autumn. Thermal summer is the longest and spring is the shortest season of the year in Poznań (Tab. 2). Thermal seasons in the warm period (the increase of temperature) began earlier in the examined period, while thermal seasons in the cold period (the decrease of temperature) tend to begin later (Fig. 1A–8A). Early spring and winter show the biggest variability of the beginning dates, while thermal autumn – the lowest one. The dates of the beginning and end of the intensive vegetation periods: early and late summer are the most stable. The greatest changeability of the length characterizes thermal winter and the lowest – late summer. Early spring tend to be shorter in the analyzed period in Poznań (Fig. 1B-8B). Longer are getting spring, summer, autumn and early winter. There were 7 years without thermal winter observed in Poznań (tab. 3), which occurred in the last twenty years of the examined period. ItemZmiany wielkości i składu transportu materiału rozpuszczonego w dolnym odcinku rzeki Obry(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Młynarczyk, Zygmunt; Słowik, MarcinThe studies concerning changes in concentration of the selected elements of dissolved matter have been conducted in the lower section of the Obra River in the vicinity of Międzyrzecz. The main research objective was to determine the changes in transportation volume of dissolved matter as well as the analysis of changes of concentration of the selected chemical elements in diverse hydrological conditions. Twelve measurement series have been completed in order to define bathymetry of the riverbed and changes of flow volume. During field research, a total of 111 samples of water have been collected in order to determine the concentration of calcium, sodium, potassium, chlorides, phosphates and the measurements of electrolytic conductivity proper performed. It has been found that the geological structure of the Obra River catchment influences the concentration of the studied elements as well as the intensity of lixiviation processes, the effect of dilution, intensity of atmospheric precipitation and fertilization in agricultural areas. Also, it has been observed that the winter half-year was characterized by much greater volumes of transported dissolved matter in comparison with the summer half-year. The reason for this could be the denudational processes, the length of the vegetative period as well as the agricultural use of land. ItemWystępowanie opadów gradu na obszarze Niziny Wielkopolskiej(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Suwała, KatarzynaThis study is an attempt to present the geographical distribution of hail occurrence in Great Poland Lowland in the years 1966–1980. The analysis is based on the data published by PIHM/IMGiW (The Institute of Meteorology and Water Management) in its annals from 1966 to 1980. According to this data, the maps of the mean number of hail days, monthly and annually, were constructed in order to determine the places where hail occurs most frequently. Additionally, the months and stations with the highest number of hail days were selected, and the maximum number of hail days in all months and stations was indicated. The material examined by the author shows that in Great Poland Lowland the mean annual number of hail days varies from one (1) in the eastern and northern part to 5.1 near Leszno. Most of the hail cases occurred in March – when the number of mean monthly hail days amounted to one (1) –, January and February. That is quite contrary to the results of other studies as generally, in most of the cases, hail occurs in the summer (Koźmiński Cz. 1964, 1965, 1968, Tuovinen 2007, 2009). When it comes to a geographical distribution of hail, the area where this precipitation increased in frequency is within Leszno and Kalisz Uplands and near Poznań. ItemPaleolimnologiczna interpretacja krzemionki biogenicznej - dyskusja na przykładzie wybranych jezior Niżu Polskiego(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Woszczyk, MichałThe paper outlines some problems in the interpretation of biogenic silica content in lacustrine sediments in the context of reconstruction of past changes in lake ecosystems throughout the Holocene. The discussion is centered on four lakes located on the Polish Lowland (Lake Sarbsko, Lake Ostrowite, Lake Skrzynka and Lake Gąsak), which display different lithology and chemical composition of bottom deposits. From the data collected it emerges that SiO2biog cannot be regarded as an unambiguous indicator of lake trophic state. Instead, paleolimnological interpretations of biogenic silica should include dilution by carbonates, SiO2ter and/or organic matter, H4SiO4-limited diatom productivity and lake water dynamics. The understanding of SiO2biog benefits from supplementation with other geochemical and paleoecological proxies. ItemZmienność przestrzenna powierzchniowych osadów plażowych brzegu morskiego wyspy Wolin(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Tylkowski, Jacek; Samołyk, MariuszThe conducted morpholithological studies of beach deposits make it possible to determine the current morphodynamics of the coast of the Wolin Island. By comparing the average value of grains composing sediments of individual zones of the beach it can be stated that the highest energy is represented by the following: beach below the water line and then beach at the water line, beach in its central part and beach at the foot of the cliff/dune. The standard deviation of sediments indicates the lowest energy diversification at the beach within its central part and at the foot of the cliff/dune, and the highest – in the zone below the water line. Further enrichment of sediments in thicker material and elimination of finer fraction occur on the beach below the water line indicating selective elution and redisposition of the material and predominance of speeds which do not allow for the precipitation of finer sediment. Saltation is the major transportation factor within the whole beach zone. Analyzing the dynamics of the sedimentary environment on the basis of the C/M diagram, it was found that the beach below the water line is mainly composed of deposits formed under the conditions of high dynamic activity which is favourable to precipitation. While the beach above the water line is constructed of material made in turbulent environment, mainly due to rolling and saltation. ItemStruktura fizyczna gruntu, zawartość substancji organicznej oraz skład chemiczny gleb w podłożach 21 stanowisk zieleni miejskiej na terenie Poznania. Część I. Struktura fizyczna gruntu(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Łukasiewicz, SzymonThis article is the first one in the series of four publications describing the condition of soil environment in the area of broadly understood centre of Poznań. The paper presents the results of studies into a ph ph ph ysical structure of the soil collected around horse chestnuts (Aesculus hippocastanum), growing in various habitats in 21 locations in the area of Poznań. In the majority of cases, 75 per cent of them, the obtained data point to a deficient ph ph ysical structure of subsoils. Only in five cases, out of a general number of 21 locations, the roots of the trees developed in soil conditions that were favourable for the plants, and which enabled them the retention of precipitation water, oxygention of rhizosph ph ere and accumulation of humus. ItemStruktura fizyczna gruntu, zawartość substancji organicznej oraz skład chemiczny gleb w podłożach 21 stanowisk zieleni miejskiej na terenie Poznania. Część II. Zawartość substancji organicznej w podłożu. Odczyn gleby(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Łukasiewicz, SzymonThe present article is the continuation of a four-part series of publications describing the condition of soil environment in the area of broadly understood centre of Poznań. It presents the content of organic substance and the reaction of subsoils collected from under horse chestnuts (Aesculus hippocastanum) growing in 21 locations in the city. The methodology of sample collection has been described in Part 1. ItemPrzykłady upwellingów w Zatoce Koszalińskiej(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Choiński, AdamThe examples of upwelling, a phenomenon that rarely occurs along the Polish part of the Baltic coast, are discussed in this study. The investigation was carried out in 2006 and 2008 near Mielno. It included temperature measurements along the cross-section perpendicular to the coast (4.5 km) at vertical sections (every 200 m) from surface to bottom, every 1 m. The obtained data allowed to determine the movement of water masses – the warm being pushed towards the open sea and the cold moving to the coast from deeper zones. The analysis of isotherm structure revealed the differences in water temperatures along the studied cross-section. ItemZastosowanie Google Maps API do multimedialnej wizualizacji informacji o obiektach przestrzennych w internecie(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Halik, ŁukaszThe present article presents Google Maps API, which is an Internet application providing access to cartographic services and technology. Owing to the application of relevant procedures and programming commands it has been used as a link combining various forms of multimedial presentation that were discussed in the article in the results of studies. A visualization system of geoinformation has been created, composed of three information levels. The author of this paper, as a participant of the Internet community, finds satisfaction that through his research he added another brick for creation of a virtual image of reality on the Internet. ItemWielkość ochładzająca powietrza - na Wybrzeżu Klifowym w rejonie Białej Góry - w sezonach letnich 2008-2009 (Woliński Park Narodowy)(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Szyga-Pluta, KatarzynaThe study includes an analysis of daily distribution of air cooling values in the selected locations of Wolin National Park. The measurements were taken in the summer seasons of 2008 and 2009. The index has been determined with regard to local qualities of the environment. It has been established that the described bioclimatic index possesses a varied daily distribution which depends on relief and vegetal coverage of the terrain. According to the scale of Conrad, the most favourable bioclimatic conditions occurred at location 1 (Beach). The daily distribution of air cooling values reflects thermal conditions and dampness. The most balanced distribution of air cooling values occurred at location 3 (Buczyna), which results from the smallest variation of temperature and dampness at this point as well as it being shielded from the wind. ItemPrzemiany stosunków wodnych w dolinie górnej Noteci do połowy XIX wieku związane z antropopresją(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Kaniecki, AlfredThe start of the great drainage work in the Upper Noteć valley is connected with the construction of the Bydgoszcz Canal in the years 1772–1774. Earlier, the economic ventures, like building of water mills or causeways, affected the area water conditions only locally. A reconstruction of the initial look of the valley still rests on historical source materials because no research has been conducted in the region to date. Here, we made use of the information from the 15th-century chronicle by Jan Długosz, of the description the 18th-century causeways, of the cartographic works of this period as well as the old descriptions of the Noteć valley. Despite attempts at a regulation of the channel, the Noteć valley from Lake Gopło to Nakło preserved its natural character until the mid-19th century, hence it was poorly accessible and swampy. It was only in the other half of the 19th century that the water conditions and the pattern of stream network in the Noteć valley were transformed radically owing to the drainage of wetland and the regulation of the river for navigational purposes. ItemGeomorfologiczne uwarunkowania rozwoju sieci komunikacyjnej na obszarze młodoglacjalnym (zlewnia Perznicy, Pojezierze Drawskie(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Szpikowski, JózefThe aim of the studies in the Perznica River catchment were relief changes caused by the development of transportation infrastructure. This type of transformation is dependable on the state of economy and the settlements. The development of transportation network in the last two hundred years was examined through the analysis of archival cartographic materials – maps from the years 1789, 1855, 1877, 1935 – and the comparison with the situation from mid 1980s. The Perznica River catchment has an area of 249 km2 and it is located in north-western Poland in the central part of the Drawskie Lakeland macroregion, which belongs to the West Pomeranian Lakeland. The heterogeneous Perznica River catchment relief has a denivelation of 159 m and is within 60 and 219 m a.s.l. The study area is within the Parsęta River lobe. A number of subzones, whose morphological diversity and diversity of sediments lithofacies is mainly a reflection of areal deglaciation of the continental ice-sheet marginal zone, has been distinguished and these are: • subzone of the internal kame moraine – the undulated moraine upland, diversified by kame forms and kettle holes, • subzone of ice-free space forms – the uplands of kame plateaux, • subzone of melt-out lake basins – Lake Wielatowo basin with a characteristic collar ridge, • morphological levels of the northern Pomeranian sloping surface – mainly flat moraine uplands and small outwashes. The economic development of the Perznica River catchment advanced in close connection with the physical and geographical context, mainly with the relief, soils and hydrological conditions. As a result, the flat moraine uplands and marginal outflow plains, which were easiest to cultivate, have been developed and populated faster than any other. Since the early medieval period, large, compact villages, often centered around big estates, were emerging in those areas. In areas with a high relief energy–kame-melt moraines, ice-free space forms and ridges around melt-out lake basins–farming entered on a larger scale from the eighteenth century. Scattered settlements in those areas forced the creation of a dense access road network to farms and fields. In the case of anthropogenic forms of transportation with denivelation exceeding 1 m in the study area, road excavations are present for 37.3 km, road undercuttings for 43.8 km and road embankments for 38.7 km in total length. That gives a high ratio of density of such forms, equal to 2.1 km per km–2. ItemCharakterystyka termiczna wklęsłej formy terenowej w okresie letnim 2010 r. na przykładzie zagłębienia międzywydmowego w Słowińskim Parku Narodowym(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2011) Kolendowicz, Leszek; Bednorz, EwaThe study is based on the measurements carried out on the Łeba Sandbar in the vicinity of the terrain station of the Department of Climatology, Adam Mickiewicz University in the period from 5 July 2010 to 6 August 2010. The interdune concave, close to the seashore, was chosen to recognize the microclimatic features of the hollow terrain form. Five measurement points were established within this hollow form: on the western, southern, eastern and northern slope and at the bottom of the concave. Thermal characteristic of each point was accomplished and thermal conditions within the hollow terrain form were described. At the same time, a description of weather conditions at standard surface has been performed, on the basis of the data from the automatic meteorological station located in the vicinity. The analysis has been made for the whole period and, separately, for the days with radiant weather.