Temporal processes and duck populations: examples from Mývatn

Studies of temporal processes at Lake Mývatn, Iceland, on three scales, millennial, centennial and decadal, are reviewed and a summary is presented of the main results of waterfowl population monitoring studies conducted during the past three decades. The characteristics of shallow, subarctic Lake Mývatn and its volcanic environment, are outlined, as well as recent conflicts between development and conservation. Mining of the bottom sediment of Lake Mývatn has been a major agent causing habitat destruction and damage to the food web. Population limitation of waterbirds at Mývatn is discussed, as three research questions and emerging answers: (1) How is reproductive output determined? All species studied showed positive correlations of production of young with levels of aquatic insects, catastrophic weather was rarely important; (2) How is the dispersion of breeding ducks determined? Densities of migratory species are determined mainly by resource levels on the breeding ground in the year before they return to the breeding area; a year-round resident species, Bucephala islandica, adjusts its density to the current availability of insect food in each of two main habitats used; (3) How are flyway populations of ducks determined? For most species, there is not enough information on total numbers and the state of the habitat on a flyway scale. In B. islandica, there are indications that the total population is limited by resources in winter. The Mývatn study area is dominated by a single, shallow and eutrophic lake and for many waterbird species the area seems to form a single functional unit. This leads to significant correlations when comparing demography with environmental conditions, such as food resources.     

Inheritance of some leaf characters inSalvia němecii HBý

Mezidruhový hybridSalvia němecii (S. nutans x 8. juri?i?ii), popsaný autorem ji? d?íve, je plně plodný. Proto byly na 238 rostlinách F₂ generace sledovány tyto znaky: typ svazk? cévních v 159;apíku, poměr délky ?apíku k délce ?epele, délko?í?kový index ?epele listové a ?lenitost ?epele, vyjád?ená poměrem ideální obrysové ploehy listu k jeho skute?né plo?e. V?ecky tyto charakteristiky srovnány se situací u rodi?ovských druh? i F₁ hybrida. Bylo zji?těno:

1. 1.
   Typ II svazk? cévních je jednodu?e a úplně dominantní nad typem III (?těpný poměr 172 : 66, X²(1) = 0.94, p =0–35).,     
   
   

The role of rock mining for maintaining Dauco carotae-Crepidetum rhoeadifoliae Hejný et Grüll in Hejný et al. 1979 — a new to Poland plant association

This work presents the Dauco carotae-Crepidetum rhoeadifoliae plant association, which is new to Poland. The association has been observed in industrial reclamation areas in the vicinity of carbonate mineral excavation sites in the central part of the Opole region. In the vast majority of cases, plots of this association developed in reclaimed areas. The majority of diagnostic species for the association was found within surveyed plots, including Verbascum thapsus, V. densiflorum and Bryum argenteum. Taxa characteristic of the alliance were also constantly present, i.e. Daucus carota, Melilotus alba, M. officinalis, Echium vulgare and Erysimum hieracifolium. This association belongs to the rarest syntaxa in Poland included in the Dauco-Melilotion alliance of ruderal communities with a predominance of hemicryptophytes, therophytes and perennials. The main diagnostic species — Crepis rhoeadifolia, belongs to very rare elements of Polish flora. It has been observed only in the southern part of the country in approx. 20 sites. Crepis rhoeadifolia had not been observed in Silesia for approx. 40 years, which is why it was considered to be an extinct taxon in this region. Rediscovering of the species allowed for diagnosing the Dauco-Crepidetum rhoeadifoliae association. This association is an example of a pioneer phytocenosis of, most likely, anthropogenic origin in Silesia.     

Význam sensibilisace při experimentální stafylokokové infekci

Резюме Исследовалось течен ие внутрикожной стаф илококковой инфекции у кроликов,-к ак нормальных, так и акти вно сенсибилизирова нных повторными инфекция ми и пассивно сенсиби лизированных сенсибилизированны х клетками селезенки и перитонеального экс судата сенсибилизированны х животных. Для развити я стафилококковой ин фекции имеет значение повыш енная чувствительно сть позднего (туберкулин ового) типа, могущая пе реноситься клетками. В сенсибили зированной ткани инфекция проте кает интенсивнее и дл ительнее, с более массивным и дли тельным сохранением микробо в в ткани, чем у контрол ьных кроликов. Эти результ аты подтверждают значение сенсибилиз ации для патогенеза стафилококковой инф екции.

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The significance of sensitization in experimental staphylococcal infection II. Průběh místni infekce při aktivní a pasivní sensibilisaciII. The course of local infection in actively and passively sensitized rabbits

Souhrn Sledovali jsme průběh intradermální stafylokokové infekce u králiků normálních, aktivně sensibilisovanych opakovanymi infekcemi a pasivně sensibilisovanych buňkami sleziny a peritoneálního exsudátu sensibilisovanych zvířat. Přecitlivělost pozdního (tuberkulinového) typu, přenosná buňkami, má vyznam pro rozvoj stafylokokové infekce. Infekce v sensibilisované tkáni probíhá intensivněji a déle, s větším a trvalejším udrzením mikrobů v tkáni nez u králí ků kontrolních. Tyto vysledky potvrzují vyznam sensibilisace pro patogenesu stafylokokové infekce. Summary The author studied the course of intradermal staphylococcal infection in normal rabbits, in rabbits made hypersensitive by repeated staphylococcal infections and in rabbits passively sensitized by the administration of spleen cells and peritoneal exudate from hypersensitive animals. Hypersensitivity to staphylococcal antigen of the delayed (tuberculin) type, which can be transmitted by cells, is important in the development of staphylococcal infection. In sensitized tissue the course of the infection is more intensive and longer, and the bacteria remain in the tissues in larger numbers and for a longer period than in the controls.

     

Die Wald- und Baumgrenze im Gebirge Hrubý Jeseník (Hohes Gesenke), Tschechoslowakei

Die vorliegende Arbeit befasst sich mit dem Verlauf der oberen Wald- und Baumgrenze im Gebirge Hrubý Jeseník (Hohes Gesenke), die hier von der Fichte gebildet wird. Es wurden die wichtigsten, die Grenze beeinflussenden Faktoren analysiert. Die Frage der Ursprünglichkeit der Bestände an der Wald- und Baumgrenze wurde auf Grund von phytometrischen und morphologischen Beobachtungen festgestellt (Abnahme der Baumhöhe, Länge der Zuwächse, Beschädigung der Fichte durch Wind und Eis, Zahl, Länge und Ausdauern der Nadeln, Verjüngung der Fichte). Die Baumgrenze erwies sich für eine Beurteilung der potentielen Waldgrenze als geeignet.     

Past vegetation dynamics of Vltavský luh, upper Vltava river valley in the Šumava mountains. Czech Republic

Six pollen diagrams from peat bogs in the Vltavsky luh (upper Vltava river valley) provide new information about vegetation reconstruction, woodland dynamics, and local development of mires during the Late-glacial and Holocene. Vegetation development began in the Oldest Dryas/B?ling with open park plant cover. In the Aller?d, woodland with Pinus and Betula developed, and in the Younger Dryas there was a steppe tundra with plants of open habitats. In the Pre-boreal, woodland tundra grew. In the Boreal, Corylus spread, and a major expansion of Picea began in the early Boreal. Picea spread during the Atlantic probably by two different migration routes. Fagus immigrated earlier than in the Bayerischer Wald and Oberpf?lzer Wald in the adjoining parts of Germany, and had its major expansion in the early Atlantic. Abies expanded in the late Atlantic. The great abundance of Abies in this area is remarkable, forming Abies or Abies-Fagus woods in less extreme habitats. Human occupation started in the Sub-boreal, as shown by both archaeology and palynology. However, human impact is recognized from anthropogenic indicators which appear in the early Atlantic. At the end of the later Sub-atlantic the development of natural woodland was interrupted by plantation of Picea according to historical and palynological evidence. Received November 13, 2000 / Accepted July 7, 2001