187 research outputs found

    A papĂ­r- Ă©s a szĂĄmĂ­tĂłgĂ©p alapĂș tesztelĂ©s összehasonlĂ­tĂł vizsgĂĄlata kĂŒlönbözƑ ite paramĂ©terek mentĂ©

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    A mĂ©rĂ©s-Ă©rtĂ©kelĂ©s IKT eszközökkel valĂł tĂĄmogatĂĄsa kĂ©pes lehet a folyamat teljes Ă©s valĂłdi megreformĂĄlĂĄsĂĄra. A felelƑssĂ©gteljes ĂĄttĂ©rĂ©shez azonban pontos informĂĄciĂłkkal kell rendelkezni arrĂłl, hogy a mĂ©dium megvĂĄltoztatĂĄs, hogyan befolyĂĄsolja az eredmĂ©nyeket. Ez egyrĂ©szt indokolt a korĂĄbbi papĂ­ alapĂș eredmĂ©nyekkel valĂł összehasonlĂ­tĂĄs vĂ©gett, mĂĄsrĂ©szrƑl nem lehetnek hĂĄtrĂĄnyosan Ă©rintett tanulĂłi körök (MolnĂĄr, 2010; Lent, 2009). Jelen tanulmĂĄny az itemek kĂŒlönbözƑ paramĂ©tereinek szempontjĂĄbĂłl vizsgĂĄlja a mĂ©dia befolyĂĄsolĂł erejĂ©t a matematika mƱveltsĂ©gterĂŒleten elsƑtƑl hatodik osztĂĄlyig

    Population dynamics of epiphytic orchids in a metapopulation context

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    Background and Aims Populations of many epiphytes show a patchy distribution where clusters of plants growing on individual trees are spatially separated and may thus function as metapopulations. Seed dispersal is necessary to (re)colonize unoccupied habitats, and to transfer seeds from high- to low-competition patches. Increasing dispersal distances, however, reduces local fecundity and the probability that seeds will find a safe site outside the original patch. Thus, there is a conflict between seed survival and colonization. Methods Populations of three epiphytic orchids were monitored over three years in a Mexican humid montane forest and analysed with spatially averaged and with spatially explicit matrix metapopulation models. In the latter, population dynamics at the scale of the subpopulations (epiphytes on individual host trees) are based on detailed stage-structured observations of transition probabilities and trees are connected by a dispersal function. Key Results Population growth rates differed among trees and years. While ignoring these differences, and averaging the population matrices over trees, yields negative population growth, metapopulation models predict stable or growing populations because the trees that support growing subpopulations determine the growth of the metapopulation. Stochastic models which account for the differences among years differed only marginally from deterministic models. Population growth rates were significantly lower, and extinctions of local patches more frequent in models where higher dispersal results in reduced local fecundity compared with hypothetical models where this is not the case. The difference between the two models increased with increasing mean dispersal distance. Though recolonization events increased with dispersal distance, this could not compensate the losses due to reduced local fecundity. Conclusions For epiphytes, metapopulation models are useful to capture processes beyond the level of the single host tree, but local processes are equally important to understand epiphyte population dynamics

    Az online projektmunka Ă©s megvalĂłsĂ­tĂĄsĂĄnak eszközei - Az oktatĂĄsi cĂ©lĂș közössĂ©gi hĂĄlĂłzatok hasznĂĄlatĂĄnak praktikus kĂ©rdĂ©sei

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    A tanulmĂĄny fĂłkuszĂĄban a projektmĂłdszer oktatĂĄsi terĂŒleten valĂł felhasznĂĄlĂĄsa ĂĄll. Ez a mĂłdszer a tanulĂĄs tanulĂĄsĂĄra nevel egy olyan problĂ©mamegoldĂł algoritmus elsajĂĄtĂ­tĂĄsĂĄval, ahol a konkrĂ©t cĂ©l elĂ©rĂ©se mĂĄsodlagos szerepet tölt be. A mĂłdszer hatĂ©konysĂĄgĂĄt növeli az IKT-, illetve online eszközök bevonĂĄsa. A cikkben ilyen mĂłdszerek Ă©s lehetƑsĂ©gek szisztematikus ĂĄttekintĂ©sĂ©t olvashatjuk

    A papĂ­r- Ă©s a szĂĄmĂ­tĂłgĂ©p alapĂș tesztelĂ©s összehasonlĂ­tĂł vizsgĂĄlata kĂŒlönbözƑ item paramĂ©terek mentĂ©n

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    A mĂ©rĂ©s-Ă©rtĂ©kelĂ©s IKT eszközökkel valĂł tĂĄmogatĂĄsa kĂ©pes lehet a folyamat teljes Ă©s valĂłdi megreformĂĄlĂĄsĂĄra. A felelƑssĂ©gteljes ĂĄttĂ©rĂ©shez azonban pontos informĂĄciĂłkkal kell rendelkezni arrĂłl, hogy a mĂ©dium megvĂĄltoztatĂĄs, hogyan befolyĂĄsolja az eredmĂ©nyeket. Ez egyrĂ©szt indokolt a korĂĄbbi papĂ­ alapĂș eredmĂ©nyekkel valĂł összehasonlĂ­tĂĄs vĂ©gett, mĂĄsrĂ©szrƑl nem lehetnek hĂĄtrĂĄnyosan Ă©rintett tanulĂłi körök (MolnĂĄr, 2010; Lent, 2009). Jelen tanulmĂĄny az itemek kĂŒlönbözƑ paramĂ©tereinek szempontjĂĄbĂłl vizsgĂĄlja a mĂ©dia befolyĂĄsolĂł erejĂ©t a matematika mƱveltsĂ©gterĂŒleten elsƑtƑl hatodik osztĂĄlyig
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