The pattern of seed banks during secondary succession on poor soils

Studies on the soil seed banks of fallow lands of different ages were carried out on poor soil abandoned fields and in a fresh coniferous forest in north-eastern Poland. The size and diversity of seed banks was studied with the seedling emergence method. Species abundance (i), density (ii), number of species from different biological groups (iii) and distribution and mean LI value (iv) were analysed as the function of fallow land age. It was found that: (i) species diversity, number of species and ln of density are linear declining function of the fallow land age; (ii) for approx. 25 years the share of diaspores of identified species groups has been relatively similar. Seed banks of 40-50-year-old fallow lands are dominated by Calluna vulgaris, while the seed bank of the old fresh coniferous forest is dominated by dicotyledonous perennials and grasses; (iii) within the first 50 years of succession the persistence of seed banks measured by the Longevity Index increases gradually

Buffering effects of soil seed banks on plant community composition in response to land use and climate

Aim Climate and land use are key determinants of biodiversity, with past and ongoing changes posing serious threats to global ecosystems. Unlike most other organism groups, plant species can possess dormant life‐history stages such as soil seed banks, which may help plant communities to resist or at least postpone the detrimental impact of global changes. This study investigates the potential for soil seed banks to achieve this. Location Europe. Time period 1978–2014. Major taxa studied Flowering plants. Methods Using a space‐for‐time/warming approach, we study plant species richness and composition in the herb layer and the soil seed bank in 2,796 community plots from 54 datasets in managed grasslands, forests and intermediate, successional habitats across a climate gradient. Results Soil seed banks held more species than the herb layer, being compositionally similar across habitats. Species richness was lower in forests and successional habitats compared to grasslands, with annual temperature range more important than mean annual temperature for determining richness. Climate and land‐use effects were generally less pronounced when plant community richness included seed bank species richness, while there was no clear effect of land use and climate on compositional similarity between the seed bank and the herb layer. Main conclusions High seed bank diversity and compositional similarity between the herb layer and seed bank plant communities may provide a potentially important functional buffer against the impact of ongoing environmental changes on plant communities. This capacity could, however, be threatened by climate warming. Dormant life‐history stages can therefore be important sources of diversity in changing environments, potentially underpinning already observed time‐lags in plant community responses to global change. However, as soil seed banks themselves appear, albeit less, vulnerable to the same changes, their potential to buffer change can only be temporary, and major community shifts may still be expected

More warm‐adapted species in soil seed banks than in herb layer plant communities across Europe

Responses to climate change have often been found to lag behind the rate of warming that has occurred. In addition to dispersal limitation potentially restricting spread at leading range margins, the persistence of species in new and unsuitable conditions is thought to be responsible for apparent time-lags. Soil seed banks can allow plant communities to temporarily buffer unsuitable environmental conditions, but their potential to slow responses to long-term climate change is largely unknown. As local forest cover can also buffer the effects of a warming climate, it is important to understand how seed banks might interact with land cover to mediate community responses to climate change. We first related species-level seed bank persistence and distribution-derived climatic niches for 840 plant species. We then used a database of plant community data from grasslands, forests and intermediate successional habitats from across Europe to investigate relationships between seed banks and their corresponding herb layers in 2763 plots in the context of climate and land cover. We found that species from warmer climates and with broader distributions are more likely to have a higher seed bank persistence, resulting in seed banks that are composed of species with warmer and broader climatic distributions than their corresponding herb layers. This was consistent across our climatic extent, with larger differences (seed banks from even warmer climates relative to vegetation) found in grasslands. Synthesis. Seed banks have been shown to buffer plant communities through periods of environmental variability, and in a period of climate change might be expected to contain species reflecting past, cooler conditions. Here, we show that persistent seed banks often contain species with relatively warm climatic niches and those with wide climatic ranges. Although these patterns may not be primarily driven by species' climatic adaptations, the prominence of such species in seed banks might still facilitate climate-driven community shifts. Additionally, seed banks may be related to ongoing trends regarding the spread of widespread generalist species into natural habitats, while cool-associated species may be at risk from both short- and long-term climatic variability and change

Okun’s Law in OECD Countries in 1990 – 2013

Politicians try to reach targets that usually contradict. It leads to lack of optimal long-term equilibrium. The main target should be the maximal growth rate of GDP and other targets should remain within predetermined limits. Politicians should influence relations between every two targets. Empirical study of relations between unemployment and GDP growth rates is done for every OECD country basing on quarterly data for 20 years. According to the results of the investigation countries are put into “strategic groups”. Paper ends with preliminary proposals for economic policy makers

Zarządzanie wiedzą w przedsiębiorstwach polskich w świetle teorii i badań empirycznych

The aim of this paper is to present the most important aspects of proper knowledge management in Polish enterprises now and in the up-coming years. All conditions for knowledge creation and the factors influencing innovativeness are reviewed both from theoretical and empirical points of view in order to meet this aim. External as well as internal „hard” and „soft” factors are described in detail in particular. Fields and domains of innovations in Polish enterprises are compared with respective topics in Polish firms with prevailing foreign capital and foreign companies as the next step. Similar comparisons are made both for scope of knowledge management and awareness of necessity of such management. Directions of the most important changes in all of these fields that are necessary in Polish enterprises are suggested as well. Lastly there are considerations of necessity and methods of respective adjustments in Polish firms. They include capital groups (holdings) and other companies operating on foreign/international markets to a rapidly changing external environment, especially to changing needs and preferences of customers

SHORT TERM AGGREGATED SUPPLY CURVES FOR OECD COUNTRIES IN 1991 – 2013

Politicians used to determine such macroeconomic targets as GDP growth rate, inflation rate, unemployment rate. They are interested in relationships between: unemployment rate and GDP growth rate (the Okun’s law), unemployment rate and inflation rate (the Philips curve) as well as between inflation rate and GDP growth rate (aggregate supply curve - SAS), put forth directly, eg. a straight line or a parabola, or indirectly, i.e. as a function Okun’s with inserted Philips function. SAS derived from the Okun’s and Philips curves estimated for OECD countries in the period 1991 to 2013 are analysed vis a vis curves reflecting direct relationships

Simple four-step procedure of parabolic B curve determination for OECD countries in 1990Q1 – 2015Q4

In theory the short-term relationship between inflation and GDP rate is known as the positive slope straight line SAS. In practice it is reflected by a concave non-monotonic function. The results of estimation depend on unusual observations. We propose a simple four-step procedure: first, basic estimation based on all observations; then estimation having ignored outliers; next, estimation on the average GDP rates for given inflation rates for the same observations; lastly, estimation skipping outlying averages. Empirical analysis for 26 OECD countries on quarterly data brought satisfactory results. They justified the determination of optimal GDP rate and corresponding inflation for every country. Finally, recommendations for policymakers have been formulated

Cele polityki gospodarczej: zależność między stopą inflacji a tempem PKB w krajach OECD w latach 1990-2013

There are always a few economic policy targets to be achieved at a given time. Politicians always strive to simultaneously achieve the optimal size for each of them. However, these targets are always at least partly contradictory. Therefore, striving to achieve an optimal level of individual targets does not lead to a stable, optimal long-term equilibrium. On the contrary, as the experiences of many countries show, whatever the number of targets, no optimal GDP rate and lack of political stability have been observed in the long run. This conclusion is supported by the results of theoretical analyses using the graphical and analytical methods of the rate of GDP as well as unemployment and inflation rates on the basis of the Okun’s law, the short-term Philips curve and the relationship between the rate of inflation and the rate of GDP. These three concepts are then combined into one model. Theoretical considerations lead to the conclusion that the target of long-term economic policy should be to maximise the rate of GDP growth while maintaining levels of other targets within specific limits. Ways to achieve this target in the long run, while maintaining political stability, are the appropriate impacts of policymakers on the relationships between every pair of targets. As a result, it is proposed (based on empirical data for the economy for a long enough period) to: – explore analytical forms and parameters of functions describing the relationships between all possible pairs of individual targets; – determine the empirical long-term equilibrium point (a combination of permissible individual economic policy targets): – directly, by solving the respective sets of equations, and, when this has no solution; – indirectly, on the basis of the indications of economic policymakers and theoreticians of various economic branches; – determine (in co-operation with politicians and theoreticians of various economic branches) the optimal combination of economic policy targets in the long run (the desired long-term equilibrium point), i.e.: the maximum growth rate of GDP and acceptable lower and upper bounds for all other targets; – determine the direction in which the empirical long-term equilibrium point should be moved in the near and further future to become the same as the desired long-term equilibrium point; – determine the factors in a given economy in a given period of time in the future that will move the long-term empirical equilibrium point in the desired direction, as well as the direction and strength of the influence of each of these factors; – implement by the policymakers the appropriate economic policy measures, i.e. to cause the replacement of the permissible combination of the individual targets of economic policy by the respective optimal combination (to influence the analytical forms and the parameters of functions describing the relationships between all pairs of individual targets, so that the rate of GDP would be the closest possible to its maximum value and at the same time boundary conditions for all other economic policy targets would be met). Of course, it is possible to depart slightly, in short periods, from maximising the rate of GDP growth in order to take into account any demand or supply shocks affecting other economic policy targets that may occur. The last step is always an assessment of the results of the economic policy by the voters. Theoretical considerations are complemented by an empirical analysis (based on quarterly data, separately for each OECD country) of the relationships between the rates of inflation and the growth rates of GDP during more or less the last two business Juglar cycles. An analysis of these relationships allows to construct “strategic groups’ maps” based on two criteria: the maximum GDP rates and the corresponding inflation rates. The analysis of these "maps" allows drawing preliminary proposals for economic policymakers. Further research (for individual OECD countries) will encompass empirical analyses of the investigations of the respective empirical long-term equilibria. The final result will be considerations on optimal economic policy measures for different countries based on results of the empirical studies.Politycy każdego kraju wyznaczają zazwyczaj kilka różnych celów gospodarczych zakładając, że każdy z tych celów osiągnie pożądany przez nich poziom. Jest to jednak niewykonalne, bowiem niektóre cele są zawsze ze sobą sprzeczne. W rezultacie, dążenie do osiągnięcia określonego poziomu każdego z celów uniemożliwia osiągnięcie stabilnej równowagi długookresowej na poziomie optymalnym. Powyższy wniosek jest poparty wynikami analizy teoretycznej (metodami graficzną i analityczną) na przykładzie wzajemnych związków między trzema wybranymi celami polityki gospodarczej: tempem PKB, stopą bezrobocia i stopą inflacji, a mianowicie: zależności opisywanych prawem Okuna, krótkookresową krzywą Philipsa oraz zaproponowanej przez autora zależności między stopą inflacji a tempem PKB. Następnie te trzy zależności połączone są w jeden nowy autorski model. Rozważania teoretyczne na podstawie tego modelu prowadzą do wniosku, że celem polityki gospodarczej powinna być maksymalizacja tempa PKB przy utrzymaniu poziomów pozostałych celów w z góry określonych granicach. Osiągnięcie tego celu w okresie długim wymaga odpowiednich oddziaływań na zależności między każdymi dwoma celami polityki gospodarczej. Do tego niezbędne są: 1) poznanie kształtów i położeń funkcji, opisujących zależności między każdymi dwoma celami polityki gospodarczej (na podstawie danych empirycznych dla danej gospodarki w okresie długim); 2) określenie empirycznego punktu równowagi długookresowej (dopuszczalnej kombinacji celów polityki gospodarczej): a) bezpośrednio, rozwiązując odpowiedni układ równań, a gdy nie ma on rozwiązania, b) pośrednio, na podstawie wskazań polityków gospodarczych i teoretyków ekonomik szczegółowych; 3) ustalenie dla okresu przyszłego (przy współpracy z politykami gospodarczymi i teoretykami ekonomik szczegółowych) optymalnej kombinacji celów polityki gospodarczej (pożądanego punktu równowagi długookresowej), tj. maksymalnego tempa wzrostu PKB oraz dopuszczalnych przedziałów wahań poziomów pozostałych celów; 4) ustalenie kierunku, w którym empiryczny punkt równowagi długookresowej powinien się przesuwać w bliższej i dalszej przyszłości aby stał się on tożsamy z pożądanym punktem równowagi długookresowej; 5) ustalenie czynników, które w danej gospodarce w okresie przyszłym spowodują przesuwanie empirycznego punktu równowagi długookresowej w pożądanym kierunku, a także określenie kierunku i siły wpływu każdego z tych czynników; 6) wdrażanie przez polityków gospodarczych odpowiedniej polityki gospodarczej, tj. takie oddziaływanie na położenie i kształt każdej z funkcji, opisujących zależności między każdymi dwoma celami polityki gospodarczej, aby tempo PKB było możliwie bliskie maksymalnego i jednocześnie, aby spełnione były warunki brzegowe dla wszystkich pozostałych celów polityki gospodarczej. Oczywiście, okresowo możliwe jest nieznaczne odstąpienie od maksymalizacji tempa wzrostu PKB w związku z koniecznością uwzględniania ewentualnych szoków podażowych lub popytowych. Rozważania teoretyczne zostały uzupełnione analizą empiryczną zależności między stopą inflacji a tempem PKB (na podstawie danych kwartalnych, oddzielnie dla każdego kraju OECD) w okresie, mniej więcej, ostatnich dwu cykli koniunkturalnych (Juglara). Analiza ta pozwoliła zbudować „mapy grup strategicznych”, uwzględniające kryteria związane z maksymalnym tempem PKB oraz współistniejącą z nim stopą inflacji. Na podstawie tych „map” wyprowadzone zostały wstępne wnioski dla polityki gospodarczej każdego z badanych krajów. Przedmiotem dalszych badań autora (również obejmujących poszczególne kraje OECD) będzie ustalenie oraz analiza empirycznych punktów równowagi długookresowej. Końcowym efektem będą pogłębione wskazówki dla polityków gospodarczych poszczególnych krajów OECD

A comparison of fuzzy logic and cluster renewal approaches for heat transfer modeling in a 1296 t/h CFB boiler with low level of flue gas recirculation

The interrelation between fuzzy logic and cluster renewal approaches for heat transfer modeling in a circulating fluidized bed (CFB) has been established based on a local furnace data. The furnace data have been measured in a 1296 t/h CFB boiler with low level of flue gas recirculation. In the present study, the bed temperature and suspension density were treated as experimental variables along the furnace height. The measured bed temperature and suspension density were varied in the range of 1131–1156 K and 1.93–6.32 kg/m3, respectively. Using the heat transfer coefficient for commercial CFB combustor, two empirical heat transfer correlation were developed in terms of important operating parameters including bed temperature and also suspension density. The fuzzy logic results were found to be in good agreement with the corresponding experimental heat transfer data obtained based on cluster renewal approach. The predicted bed-to-wall heat transfer coefficient covered a range of 109–241 W/(m2K) and 111–240 W/(m2), for fuzzy logic and cluster renewal approach respectively. The divergence in calculated heat flux recovery along the furnace height between fuzzy logic and cluster renewal approach did not exceeded ±2%

Forecast in Economic Science

W dwuczęściowym artykule omówione są podstawowe zagadnienia z zakresu przewidywania w naukach ekonomicznych. Przedmiotem rozważań w niniejszej części pierwszej są najważniejsze podstawowe pojęcia oraz prognozowanie na podstawie modeli statystycznych, modeli trendu oraz liniowych, jedno- i wielorównaniowych modeli ekonometrycznych. Zdarzenia są skutkiem autonomicznych albo wtórnych działań przyrody albo człowieka (grupy osób, społeczeństwa). Ze zdarzeniami nierozłącznie związana jest niepewność, którą można ograniczać, podejmując rozmaite działania. Ich efektem jest przekształcanie niepewności w ryzyko. Ważnym sposobem tego przekształcania jest przewidywanie, w którym stosuje się metody heurystyczne bądź modele matematyczne, statystyczne lub ekonometryczne, wykorzystując, w większym albo mniejszym stopniu, wiedzę dotyczącą przeszłości. Prognozowanie na podstawie modeli statystycznych polega na ekstrapolowaniu zaobserwowanych w przeszłości: poziomu zmiennej, jej dynamiki albo współzależności z inną zmienną. Metody te cechuje relatywna prostota, która, z reguły, okupiona jest ich niską jakością prognostyczną. Prognozowanie na podstawie modeli ekonometrycznych zwykle rozpoczyna się od ustalenia wielkości błędu prognozy ex ante. Jeśli są one akceptowalne, sporządza się prognozę, podobnie jak w przypadku modeli statystycznych, podstawiając do poszczególnych równań wartości prognozowane odpowiednich zmiennych objaśniających. Modele ekonometryczne są jednak znacznie bardziej rozbudowane. W rezultacie, znacznie większy jest koszt związany z nakładami sił i środków. Dzięki temu mają one, na ogół, znacznie większą zdolność prognostyczną.This two-part article discusses the basic issues of prediction in economics. Explored in the this first part are the most important basic concepts and forecasting based on statistical models and linear trend models, single and multiequation econometric models. Occurrences are the result of autonomous or secondary nature or human action (a group of people, society). With events inseparably linked is the uncertainty, which can be limited by taking various actions. Their effect is to transform uncertainty into risk. An important way of transformation is a prediction, which uses heuristics or mathematical models, statistical or econometric, utilizing, to a greater or lesser degree, knowledge of the past. Forecasting based on statistical models relies on extrapolating observed in the past: the level of the variable, its dynamics or interaction with another variable. These methods are characterized by relative simplicity, which, as a rule, paid with their poor quality prognostic. Forecasting based on econometric models usually starts from the size of the forecast error ex ante. If they are acceptable, shall be made a forecast as in the case of statistical models, substituting for the individual equations predicted values relevant explanatory variables. Econometric models are much more complex. As a result, cost associated with the expenditure of power and resources are significantly increased. Thanks to this they have, generally, much greater predictive ability