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  • Growth  (3)
  • Nitrogen  (2)
  • Barley  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Competition causes regular spacing of alder in Alaskan shrub tundra (1989)
    Springer
    Oecologia 79 (1989), S. 412-416 
    Details
    ISSN: 1432-1939
    Keywords: Alder ; Competition ; Growth ; Regular spacing ; Tundra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Alders (Alnus crispa) in shrub tundra in northern Alaska showed significant regularity of spacing. Removal of neighboring alder shrubs stimulated nutrient accumulation and growth of remaining alders but did not stimulate nutrient accumulation or growth of any other shrub species. This demonstrates that neighboring alders competed with one another and that, when alders were removed, the resources made available were used preferentially by remaining alders rather than by the community in general. Neither patterns of seedling establishment nor patterns of frostrelated features could explain the regular distribution of alder. We suggest that regular patterns of plant distribution are restricted to sites of low-resource availability, because in these habitats (1) there is strong competition for a scarce resource, and (2) there are only one or a few dominant species to compete for these resources in a given canopy height or rooting depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384322
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  • 2
    Electronic Resource
    Electronic Resource
    Seasonal control over allocation to reproduction in a tussock-forming and a rhizomatous species of Eriophorum in central Alaska (1989)
    Springer
    Oecologia 78 (1989), S. 27-34 
    Details
    ISSN: 1432-1939
    Keywords: Eriophorum vaginatum ; E. scheuchzeri ; Growth ; Flowering ; Phenology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The evergreen tussock-forming Eriophorum vaginatum revealed consistently earlier (c. 1 moth) phenology and greater biomass per tiller than the summergreen rhizomatous E. scheuchzeri in all four components measured (vegetative and reproductive shoots and stems) under the same climatic regime in central Alaska over one growing season. Greatest allocation to vegetative shoot growth occurred in mid-summer in both species. The tussock growth form of E. vaginatum raised shoot meristems 25–30 cm above the soil surface, where temperatures were warmer, permitting shoot growth to begin earlier in spring and continue longer in autumn than in E. scheuchzeri. Consequently, E. vaginatum was able to allocate reserves to reproductive tillers primarily in autumn and early spring, times when minimal reserves were required for vegetative growth. By contrast, the rhizomatous E. scheuchzeri had a more constrained growing season, and allocation to reproduction coincided with allocation to vegetative growth. For this reason, reserves were drawn down more fully in mid-summer in E. scheuchzeri than in E. vaginatum. The more conservative use of nutrient stores in E. vaginatum may relate to its great longevity, reduced allocation to reproduction (including low seedling recruitment), and relatively stable habitats. The mid-seasonal pulse of allocation to reproduction in E. scheuchzeri appears viable only in relatively fertile disturbed sites, where the soil nutrient supply is sufficient to support simultaneous allocation to vegetative growth and reproduction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377194
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  • 3
    Electronic Resource
    Electronic Resource
    Differences in carbon and nutrient fractions among arctic growth forms (1988)
    Springer
    Oecologia 77 (1988), S. 506-514 
    Details
    ISSN: 1432-1939
    Keywords: Carbohydrate ; Growth form ; Nitrogen ; Phosphorus ; Tundra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In a survey of 28 plant species of 6 major growth forms from Alaskan tundra, we found no consistent difference among growth forms in the chemical nature of stored reserves except for lichens and mosses (which stored C primarily as polysaccharides) and shrubs (which tended to store C more as sugars than as polysaccharides). Forbs and graminoids showed particularly great diversity in the chemical nature of stored reserves. In contrast, C, N, and P chemistry of leaves was strikingly similar among all species and growth forms. Concentrations of stored reserves of C, N, and P were highest and showed greatest seasonal fluctuations in forbs and graminoids but were relatively constant in evergreen shrubs. From this information, we draw three general conclusions: (1) the photosynthetic function of leaves strongly constrains leaf chemistry so that similar chemical composition is found in all species and growth forms: (2) the chemical nature of storage reserves is highly variable, both within and among growth forms; (3) the concentration and seasonal pattern of storage reserves are closely linked to growth-form and reflect growth-form differences in woodiness, phenology, and relative dependence upon concurrent uptake vs. storage in support of growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377266
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  • 4
    Electronic Resource
    Electronic Resource
    Environmental and physiological factors governing nutrient resorption efficiency in barley (1992)
    Springer
    Oecologia 90 (1992), S. 120-126 
    Details
    ISSN: 1432-1939
    Keywords: Nitrogen ; Nutrient stress ; Nutrient resorption ; Translocation ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Barley plants (Hordeum vulgare cv. stepto) were grown in a greenhouse under two nutrient and water levels and four treatments intended to alter sourcesink relationships, in a factorial experiment designed to study factors governing efficiency of nutrient resorption from senescing leaves. Plant growth was enhanced in high-nutrient treatments, leading to higher concentrations of nitrogen (N) and phosphorus (P) in leaves and ears. Water stress reduced growth, but plants in waterstressed treatments had equal or higher nutrient concentrations than watered plants. Nutrient resorption efficiency was higher at low than at high nutrient availability, and was higher in watered than in water-stressed plants. Treatments in which sink strength was increased had enhanced resorption efficiency, as well as those in which the source activity was reduced. Our data show that the amount of nutrient resorbed and the efficiency of the resorption process depend on plant nutrient and water status, and that the presence of an active sink strongly enhances nutrient resorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317817
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  • 5
    Electronic Resource
    Electronic Resource
    Physiological determinants of growth rate in response to phosphorus supply in wild and cultivated Hordeum species (1989)
    Springer
    Oecologia 79 (1989), S. 96-105 
    Details
    ISSN: 1432-1939
    Keywords: Allocation ; Growth ; Phosphorus ; Photosynthesis ; Seed size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Under favorable nutrition, accessions of the weedy barleygrass (Hordeum leporinum and H. glaucum) had a higher relative growth rate (RGR) than did accessions of cultivated barley (H. vulgare) or its wild progenitor (H. spontaneum). RGR was not positively correlated with the presumed level of soil fertility at the collection site of an accession either within or among species. RGR was reduced more strongly by low-P supply in the progenitor than in the crop or weed, indicating that selection of cultivars to grow in fertile soils had not reduced their potential to grow effectively under low-P conditions. Seed and embryo masses were more important than RGR in determining plant size. Relative differences among assessions in plant size declined with time, because (1) accessions with small seeds had a higher RGR, and (2) RGR of large-seeded accessions declined with time. Absolute growth rate correlated positively with leaf area and negatively with photosynthetic rate per unit leaf area. Under favorable nutrition, maximum photosynthetic rate correlated negatively with leaf length and therefore was higher in the weeds than in the crop or progenitor accessions. P absorption potential did not differ consistently among species but generally increased in response to P stress. Cultivars produced a few tall tillers, whereas weeds and progenitors produced many small tillers. The cultivar had a larger proportion of reproductive tillers, allocated a larger proportion of biomass to grain, and produced larger grains than did the weedy accession. By contrast, the weed began maturing seeds sooner, produced more reproductive tillers, and produced more grains per car and per plant than did the cultivar. The study suggests two major conclusions: (1) A low RGR is not an adaptation to low P supply in annual Hordeum species. (2) Seed size is the major determinant of early plant size between accessions in these Hordeum species under favorable nutrition. However, large seed size indirectly results in a low RGR because of the inverse relationship between plant size and RGR and results in a low photosynthetic rate because of the inverse relationship between leaf size and photosynthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378245
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  • 6
    Electronic Resource
    Electronic Resource
    Adaptation of selected trees and grasses to low availability of phosphorus (1983)
    Springer
    Plant and soil 72 (1983), S. 283-287 
    Details
    ISSN: 1573-5036
    Keywords: Barley ; Chinochloa ; Growth rate ; Nutrient deficiency ; Nutrient stress ; Phosphorus fractions ; Root-shoot ratio ; Taiga
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract High-nutrient-adapted and low-nutrient-adapted species of New Zealand tussock grasses (Chionochloa), barley (Hordeum), and several taiga trees were grown at three rates of phosphorus supply. Low-nutrient-adapted species in each group of species had similar (grasses) or lower (trees) capacities for phosphate absorption, were less efficient in producing biomass (i.e. had higher nutrient concentrations), and grew more slowly than high-nutrient-adapted species. I conclude that the major adaptation to low nutrient availability in each of these comparisons is a slow growth rate that reduces the annual nutrient requirement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02181967
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