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  • Annual and perennial grasses  (1)
  • Carbon isotope discrimination  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Leaf carbon isotope discrimination and vegetative responses of Dryas octopetala to temperature and water manipulations in a High Arctic polar semi-desert, Svalbard (1993)
    Springer
    Oecologia 95 (1993), S. 463-469 
    Details
    ISSN: 1432-1939
    Keywords: Arctic physiological ecology ; Carbon isotope discrimination ; Climate change ; Water-use efficiency ; Polar semi-desert
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Integrative ecophysiological and vegetative responses of Dryas octopetala were measured in response to field perturbations of temperature, precipitation and their interactions in a polar semi-desert in Svalbard, Norway (79°N, 12°E). Leaf carbon isotope discrimination (Δ), total leaf nitrogen concentration and leaf development were determined for photosynthetic leaves collected during the last week of August 1991, after one season of manipulations. Individual leaf weight and the total mass of leaf tissue were significantly lower when water was added, irrespective of temperature regime. Leaf carbon isotope discrimination and estimated long-term c i/c avalues (the ratio of CO2 concentration in leaf intercellular spaces to that in the atmosphere) were significantly higher under all three field manipulation treatments, and Δ was significantly reduced when Dryas was grown under drought conditions in a related greenhouse study. Nitrogen concentrations of plants from the field experiment were significantly lower under warmed conditions regardless of water regime. Our results indicate that changes in environmental conditions in high arctic settings will result in alterations of Dryas leaf gas exchange, as expressed by increases in carbon isotope discrimination, which may be accompanied by shifts in leaf nitrogen content and leaf biomass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317428
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  • 2
    Electronic Resource
    Electronic Resource
    Capture and allocation of nitrogen byQuercus douglasii seedlings in competition with annual and perennial grasses (1991)
    Springer
    Oecologia 87 (1991), S. 459-466 
    Details
    ISSN: 1432-1939
    Keywords: Soil nitrogen competition ; Competitive interactions ; Oak savannas ; Annual and perennial grasses ; Quercus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The spatial overlap of woody plant root systems and that of annual or perennial grasses promotes competition for soil-derived resources. In this study we examined competition for soil nitrogen between blue oak seedlings and either the annual grassBromus mollis or the perennial grassStipa pulchra under controlled outdoor conditions. Short-term nitrogen competition was quantified by injecting15N at 30 cm depth in a plane horizontal to oak seedling roots and that of their neighbors, and calculating15N uptake rates, pool sizes and15N allocation patterns 24 h after labelling. Simultaneously, integrative nitrogen competition was quantified by examining total nitrogen capture, total nitrogen pools and total nitrogen allocation.Stipa neighbors reduced inorganic soil nitrogen content to a greater extent than didBromus plants. Blue oak seedlings responded to lower soil nitrogen content by allocating lower amounts of nitrogen per unit of biomass producing higher root length densities and reducing the nitrogen content of root tissue. In addition, blue oak seedlings growing with the perennial grass exhibited greater rates of15N uptake, on a root mass basis, compensating for higher soil nitrogen competition inStipa neighborhoods. Our findings suggest that while oak seedlings have lower rates of nitrogen capture than herbaceous neighbors, oak seedlings exhibit significant changes in nitrogen allocation and nitrogen uptake rates which may offset the competitive effect annual or perennial grasses have on soil nitrogen content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320407
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    Paper (German National Licenses)
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