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  • Germination  (1)
  • Vegetation of deforested sites  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Effects of plant density and nutrient levels on fruit polymorphism in Atriplex sagittata (1999)
    Springer
    Oecologia 119 (1999), S. 63-72 
    Details
    ISSN: 1432-1939
    Keywords: Key wordsAtriplex sagittata ; Bet-hedging ; Fruit polymorphism ; Germination ; Maternal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Atriplex sagittata is a heterocarpic species producing three types of fruits which differ in morphology and ecological properties. This study focused on variation in biomass allocation into particular fruit types under different density and fertilization levels. The reduction in total weight under stressful conditions was accompanied by a reduction of reproductive structures in terms of both total fruit production and mean fruit weight. Allocation of biomass to particular fruit types under different density-fertilization treatments showed considerable variation. The non-dormant, bracteolate fruit type (termed C) contributed 80–90% to the total fecundity and its production was not affected by density-fertilization treatments. The production of this fruit type is higher in the upper part of the maternal plant stem. Production of the very dormant ebracteate fruit type (termed A) increased under favourable conditions and was greater on the lower part of the stem, whereas more of the so-called type B fruit (covered by bracteoles and exhibiting dispersal and dormancy characteristics intermediate between types A and C) was produced under suboptimal conditions and was concentrated in the middle part of the plant body. This pattern contradicts to some extent the theory that deeply dormant and less dispersible fruits will be produced under stressful conditions and may be considered a new model for the behaviour of plants with more than two heterocarpic fruits. The type B fruit, intermediate in both morphology and ecological behaviour, provides a continuum between extreme strategies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050761
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  • 2
    Electronic Resource
    Electronic Resource
    Pattern of species dominance and factors affecting community composition in areas deforested due to air pollution (1994)
    Springer
    Plant ecology 112 (1994), S. 45-56 
    Details
    ISSN: 1573-5052
    Keywords: Vegetation of deforested sites ; Calamagrostis yillosa ; Species diversity ; Dominance ; Canonical Correspondence Analysis ; Indicator values ; Soil acidity ; Krušné hory Mountains ; Czech Republic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Vegetation of mountain areas affected by SO2 pollution (Krušné hory Mts., Czech Republic) was analysed using multivariate methods. Communities with prevailing species Calamagrostis villosa, a rhizomatous grass expanding into deforested sites, were sampled by Braun-Blanquet relevé method. Canonical correspondence analysis was used to assess the effect of environmental variables (soil removal, deforestation, and shading). To test the effects of light, moisture, soil acidity and nitrogen, mean sample indicator values were correlated a posteriori with sample axes on ordination scores. Light, soil acidity, moisture, and site history (in terms of past deforestation and soil removal applied in reclamation procedures) were found to be the main factors responsible for the community composition. Nitrogen level had not a significant effect on the community composition. When analyzing the whole data set, i.e. including also remnants of natural spruce forests, light was the factor affecting at most the composition of communities. Within the bare spot vegetation, if treated separately, the highest variation was found along the soil acidity/moisture gradient. The effect of soil removal was only obvious at early successional stages. Species diversity increased with moisture and decreased with soil acidity. Species exhibiting S- and/or R-strategy are successful on extremely acid soils whereas forbs present in bare spots appear to be supported by disturbances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00045099
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