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  • Articles  (4)
  • Vegetation  (2)
  • macrophyte communities  (2)
  • Springer  (4)
  • 1
    ISSN: 1432-1939
    Keywords: Phenolics ; Stress gradient ; Vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The chemical constituency of flowering dogwood (Cornus florida L.) and red maple (Acer rubrum L.) foliage was analyzed over a species compositional gradient to test the hypothesis that over subtle gradients of moisture and nutrient availability production of phenolic compounds will be increased on sites of greatest stress. Calcium and nitrogen concentrations declined along the gradient in both species, while phosphorus showed a significant decline only in red maple. Lignin concentrations in both species were unrelated to the vegetation gradient, but astringent phenolics increased by 156% and 159% in dogwood and red maple, respectively. The correlation between production of polyphenolds and site quality supports previous observations that under conditions of environmental stress production of many secondary compounds is increased, and suggests that this relationship is significant over subtle environmental gradients.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 79 (1989), S. 563-565 
    ISSN: 1432-1939
    Keywords: Phenolics ; Fine roots ; Stress gradient ; Vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chemical quality of fine roots (〈1 mm diameter) was determined over a gradient of species composition in the Mixed Mesophytic Forest Region. Ash-free nitrogen, calcium, and phosphorus concentrations of roots declined by 49, 41, and 72%, respectively, over a gradient of increasing soil acidity (pH 5.3 to 4.7). Lignin concentration was unrelated to either the vegetation gradient or any of the soil changes it encompassed; however, astringent phenolics increased by 275% over the same gradient. Trends in the chemical constituency of fine roots suggest that the production of phenolics in below-ground plant parts is increased on nutrient-poor sites. This response is best related to changes in species composition, especially increasing importancy of Quercus spp.
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  • 3
    ISSN: 1573-5117
    Keywords: eutrophication ; acidification ; macrophyte communities ; weakly mineralized streams ; France
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Northern Vosges streams are subjected to acidification upstream and to eutrophication downstream. A bio-indicator scale of the degree of eutrophication and of the level of acidification, based on four aquatic macrophyte communities, was established in these weakly mineralized streams. Aquatic plant communities therefore begin as Group A, develop into Group B and become Group C or D downstream. The A community was characterized by bryophytes (Scapania undulata, Sphagnum sp.) and Potamogeton polygonifolius in oligotrophic, acidified to weakly acidified, and poorly buffered streams. The B community, defined by P. polygonifolius and the appearance of Ranunculus peltatus and Callitriche species (C. platycarpa, C. hamulata) was found in oligotrophic waters with a higher buffer capacity than the A community. The C community was determined by the disappearance of P. polygonifolius and the appearance of Elodea species (E. canadensis, E. nuttallii) and rare species in mesotrophic and neutral streams. The D community, with very high nutrient loading, was characterized by the abundance of Callitriche obtusangula, by the presence of Amblystegium riparium, Fissidens crassipes and the development of filamentous algae. This macrophyte sequence corresponded to an upstream to downstream zonation, which was characterized by an increase in buffer capacity and in nutrient levels and a decrease in protons and aluminium load.
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  • 4
    ISSN: 1572-9710
    Keywords: specific richness ; diversity ; macrophyte communities ; stream ; Northern Vosges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationships between water chemistry and aquatic macrophyte species were studied in an attempt to evaluate the impact of eutrophication on aquatic macrophyte diversity in weakly mineralized streams in the Northern Vosges mountains (NE France). The macrophyte specific richness and abundance increased along an upstream to downstream zonation, which was characterized by an increase in mineralization and nutrient levels. A comparison of aquatic macrophyte diversity of two streams has shown the impact of human-induced perturbations (fish-farms, domestic sewage) in such weakly mineralized and poorly buffered waters. Disturbed sites with very high nutrient loading were characterized by a low vascular plant richness and by the presence of filamentous algae. In order to preserve the floristic diversity of weakly mineralized streams, water quality should be improved, the riverbanks restored and discharges reduced.
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