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  • 2000-2004  (1)
  • 1980-1984  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 59 (1983), S. 366-369 
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seeds of Typha latifolia were exposed to leaf extracts, leaf pieces, and soil water from adult plants of T. latifolia. In liquid culture, only extracts of concentration greater than or equal to 3% (dry weight to volume) inhibited seed germination. Adding soil to the liquid cultures increased the inhibition of seed germination by extracts. The inhibitory effects of extracts were correlated with the development of water molds in the cultures; prior to the development of water molds, even 15% extracts were not inhibitory to germination. In contrast to results from extracts; neither 3% concentrations of senesced leaf pieces nor soil surface water from one year old pots of T. latifolia had any detrimental effects on germination. Seeds sown into pots containing established T. latifolia germinated as well as seeds sown into control pots. These results do not support the contention that T. latifolia inhibits the germination of its seeds by the release of allelopathic substances.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 50 (1981), S. 158-161 
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The objective of this study was to separate the effects of plant biomass and growth rate on vegetative reproduction in two species of cat-tail, Typha latifolia and T. angustifolia. Replicate clones of both species were grown under conditions of 100%, 42%, 24%, and 9% full sunlight with harvests at 41, 70, and 91 days after shading. T. angustifolia produced most of its vegetative offspring before the first harvest and increased biomass over the remainder of the experiment by increasing the size of its ramets. In contrast, T. latifolia produced vegetative offspring gradually throughout the experiment adding new ramets only after existing clones were of mature size. As a result of these differences in the cloning process, T. angustifolia showed little correlation between vegetative reproduction and clone size while T. latifolia showed a strong correlation between gegetative reproduction and clone size at the three highest light intensities. Growth rates, average clone size and vegetative reproduction were all reduced by reductions in light intensity for both species. However, no effect of growth rate on the relationship between clone size and vegetative reproduction in T. latifolia could be detected. T. latifolia showed greater survivorship and more biomass production under 9% light than T. angustifolia indicating a greater shade tolerance.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Seasonal excavations of ramet systems in overlapping natural populations of Typha latifolia and T. angustifolia revealed intrapopulation variation in ramet size and reproduction. Reproductive “states” were recognized based on whether or not a ramet had flowered and the number of offspring ramets it possessed. As the growing season progressed, the populations became increasingly heterogeneous in their reproductive-state composition with the largest size classes of ramets containing the greatest number of reproductive states. Therefore, despite a strong correlation between size and reproduction, average ramet size was considered to be an inadequate predictor of population growth in ramet numbers. Results for vegetative reproduction and ramet mortality indicate that the T. latifolia population was growing while the T. angustifolia population was approximately stable. In contrast to most results reported for other species, the frequency distributions of ramet size classes showed T. angustifolia to have a normally distributed population. A slight degree of positive skewing occurred in T. latifolia with the greatest skewing at the end of the growing season. Despite the lack of strong skewing of ramet weights, evidence from other sources have demonstrated that competition was intense and we hypothesize that competition in clonal populations may not not always act to cause positive skew in weight distributions.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant ecology 147 (2000), S. 105-115 
    ISSN: 1573-5052
    Keywords: Biodiversity ; Conservation ; Native communities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The coastal prairie ecoregion is located along the northwestern coastal plain of the Gulf of Mexico in North America. Because of agricultural and urban development, less than 1% of the original 3.4 million ha of this ecosystem type remains in native condition, making it one of the most endangered ecosystems in North America. The objective of this study was to characterize the vegetation and environmental relationships in a relatively pristine example of lowland coastal prairie in order to provide information for use in conservation and restoration. The study area was a small, isolated prairie located near the southern boundary of the coastal prairie region. Samples were taken along three parallel transects that spanned the prairie. Parameters measured included species composition, elevation, soil characteristics, indications of recent disturbance, above-ground biomass, and light penetration through the plant canopy. Fifty-four species were found in the 107 0.25-m2 plots and a total of 96 species were found at the site. Only two non-native species occurred in sample plots, both of which were uncommon. Cluster analysis was used to identify six vegetation groups, which were primarily dominated by members of the Poaceae or Asteraceae. A conspicuous, natural edaphic feature of the prairie was the presence of `mima' mounds, which are raised areas approximately 0.5 to 1 m high and 5 to 10 m across. Indicator species analysis revealed a significant number of species that were largely restricted to mounds and these were predominately upland and colonizing species. Ordination was performed using nonmetric, multidimensional scaling. The dominant environmental influence on species composition was found to be elevation and a host of correlated factors including those associated with soil organic content. A secondary group of factors, consisting primarily of soil cations, was found to explain additional variance among plots. Overall, this prairie was found to contain plant associations that are now rare in the surrounding landscape. Within the prairie, plant groups were largely separated by a suite of environmental conditions associated with topography. These results suggest that conservation and restoration efforts will need to carefully consider local topographic influences in order to be successful.
    Type of Medium: Electronic Resource
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