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  • Springer  (14)
  • 1995-1999  (6)
  • 1990-1994  (8)
  • 1970-1974
  • 1995  (6)
  • 1990  (8)
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  • 1995-1999  (6)
  • 1990-1994  (8)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 102 (1995), S. 361-370 
    ISSN: 1432-1939
    Schlagwort(e): Picea abies (L.) Karst ; Ammonium ; Nitrate ; 15N ; Tracer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Throughfall nitrogen of a 15-year-old Picea abies (L.) Karst. (Norway spruce) stand in the Fichtelgebirge, Germany, was labeled with either 15N-ammonium or 15N-nitrate and uptake of these two tracers was followed during two successive growing seasons (1991 and 1992). 15N-labeling (62 mg 15N m-2 under conditions of 1.5 g N m-2 atmospheric nitrogen deposition) did not increase N concentrations in plant tissues. The 15N recovery within the entire stand (including soils) was 94%±6% of the applied 15N-ammonium tracer and 100%±6% of the applied 15N-nitrate tracer during the 1st year of investigation. This decreased to 80%±24% and 83%±20%, respectively, during the 2nd year. After 11 days, the 15N tracer was detectable in 1-year-old spruce needles and leaves of understory species. After 1 month, tracer was detectable in needle litter fall. At the end of the first growing season, more than 50% of the 15N taken up by spruce was assimilated in needles, and more than 20% in twigs. The relative distribution of recovered tracer of both 15N-ammonium and 15N-nitrate was similar within the different foliage age classes (recent to 11-year-old) and other compartments of the trees. 15N enrichment generally decreased with increasing tissue age. Roots accounted for up to 20% of the recovered 15N in spruce; no enrichment could be detected in stem wood. Although 15N-ammonium and 15N-nitrate were applied in the same molar quantities (15NH 4 + : 15NO 3 - =1:1), the tracers were diluted differently in the inorganic soil N pools (15NH 4 + /NH 4 + : 15NO 3 - /NO 3 - =1:9). Therefore the measured 15N amounts retained by the vegetation do not represent the actual fluxes of ammonium and nitrate in the soil solution. Use of the molar ammonium-to-nitrate ratio of 9:1 in the soil water extract to estimate 15N uptake from inorganic N pools resulted in a 2–4 times higher ammonium than nitrate uptake by P. abies.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 82 (1990), S. 158-161 
    ISSN: 1432-1939
    Schlagwort(e): Air pollution ; Acid rain ; Photosynthesis ; Nutrition ; Picea abies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Photosynthetic rates and nutrient contents of spruce needles were measured in a region with high levels of air pollution in NE Bavaria, Germany (FRG), and compared to spruce grown under clean air conditions at Craigieburn, in the South Island of New Zealand (NZ). The absolute rates of CO2 uptake, the slope of the CO2 response curve at 240 μl l−1 internal CO2 concentration, and the change of photosynthetic rates with needle age at ambient and saturated CO2 concentrations were virtually identical at both measuring sites. These results confirm an earlier conclusion, that there is no long-term effect of atmospheric pollutants directly on photosynthetic CO2 uptake rates with persistent exposure at the FRG site to high levels of anthropogenic air pollution. Photosynthetic capacity at saturating CO2 concentration was three times higher in the NZ spruce. Needles with high photosynthetic capacity in NZ had lower nitrogen and higher calcium concentrations per unit dry weight but higher concentrations of nitrogen, phosphorus, potassium, magnesium and calcium per unit leaf area, and twice the specific leaf weight.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 82 (1990), S. 427-429 
    ISSN: 1432-1939
    Schlagwort(e): Insectivorous plants ; Insect capture ; Leaf growth ; Nitrogen storage ; Drosera
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Rates of insect capture increased with leaf area in the insectivorous plant Drosera rotundifolia, and growth of new leaves was related to insect capture. However, increased leaf growth was counterbalanced by leaf abscission which was in turn related to insect capture and leaf growth. Leaf loss equaled leaf growth in plants having natural rate of insect capture. A large proportion of the nitrogen gain from prey was stored in the hypocotyl; it was estimated from feeding experiments that about 24% to 30% of the nitrogen stored in the hypocotyl after winter originated from insect capture in the previous season. The effect of insect capture is discussed in relation to the life cycle of Drosera.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 82 (1990), S. 355-361 
    ISSN: 1432-1939
    Schlagwort(e): Vine ; Xylem water flow ; Entadopsis ; Serjania ; Cyclanthera
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A method for determining the mass flow rate of xylem water in thin stems under natural field conditions is presented. Diurnal courses of xylem water flow and stomatal conductance of the vines Entadopsis polystachya, Cyclanthera multifoliolata, and Serjania brachycarpa were examined in a tropical deciduous forest on the west coast of Mexico. E. polystachya (leaf area 23.6 m2) had a maximum water flow rate of 6.50 kg h-1 or 1.44 kg cm-2 stem basal area h-1; daily water use was 2.00 kg m-2 leaf area day-1. S. brachycarpa (leaf area 4.5 m2) and C. multifoliolata (leaf area 3.6 m2) had a maximum water flow rate of 0.72 and 0.19 kg h-1 or 0.63 and 0.92 kg cm-2 stem basal area h-1. Daily water use was 1.26 and 0.39 kg m-2 leaf area day-1, respectively. The daily courses of xylem water flow were strongly influenced by the orientation of the leaf area to irradiance and its intensity. While leaves of E. polystachya had a constant high stomatal conductance during the day, S. brachycarpa had a maximum stomatal opening in the morning followed by continuous closure during the rest of the day. In contrast to the woody species, the herbaceous C. multifoliolata exhibited a strong midday depression of stomatal conductance and wilting of its leaves. The leaf biomass accounted for 8% (Entadopsis), 16% (Serjania), and 23% (Cyclanthera) of above-ground biomass. The relation of sapwood area to leaf area supplied (Huber value) was 0.19 (Entadopsis), 0.18 (Serjania), and 0.06 (Cyclanthera) cm2 m-2
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1432-1939
    Schlagwort(e): Carbohydrate ; Growth ; Nitrogen ; Phaseolus lunatus ; Storage
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Growth, photosynthesis, and storage of nitrogen (N) and total non-structural carbohydrates (TNC) of a perennial wild type and an annual cultivar of lima bean (Phaseolus lunatus) were examined at different light intensities and N supplies. Relative growth rate and photosynthesis increased with light and N availability. N limitation enhanced biomass allocation into root rather than into shoot, while light limitation enhanced growth of leaf area. The TNC concentrations increased with light intensity and thus with photosynthesis, while the concentrations of organic N and nitrate decreased. Increasing N supply had the opposite effect. Therefore, TNC and organic N concentrations were negatively correlated (r=−0.90). Pool size of N or TNC increased with N and light availability when either resource was non-limiting, but increased little or remained constant when either resource was limiting. Storage reached a minimum when both resources were supplied at an equal rate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Naturwissenschaften 77 (1990), S. 453-453 
    ISSN: 1432-1904
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Allgemeine Naturwissenschaft
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Plant ecology 121 (1995), S. 79-87 
    ISSN: 1573-5052
    Schlagwort(e): Canopy ; Evaporation ; Leaf area index ; Scaling ; Surface conductance ; Stomata
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We examine conductances for evaporation from both vegetation and soil in response to environmental variables. Data from a vertically-structured pristine forest of Nothofagus are presented as an example of the effects of biodiversity on the scaling of conductances between tiers of plant organisation. Available data sets of maximum leaf stomatal conductances (g lmax ) and bulk vegetation surface conductances (G smax ) are compared. Overall, the ratio G smax /g lmax is consistently close to 3 for seven major vegetation types of diverse structure. An analytical model accounts for this close relationship, and in particular how G smax is conservative against changes in leaf area index because of the compensating decrease in plant canopy transpiration and increase in soil evaporation as leaf area index diminishes. The model is also successfully tested by comparison with canopy conductances of emergent trees measured in the Nothofagus forest. The constraint of vegetation surface conductance and evaporation via environmental regulation by irradiance, air saturation deficit and root zone water supply are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 1990-02-01
    Print ISSN: 0029-8549
    Digitale ISSN: 1432-1939
    Thema: Biologie
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 1990-03-01
    Print ISSN: 0029-8549
    Digitale ISSN: 1432-1939
    Thema: Biologie
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 1995-01-01
    Print ISSN: 0029-8549
    Digitale ISSN: 1432-1939
    Thema: Biologie
    Publiziert von Springer
    Standort Signatur Erwartet Verfügbarkeit
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