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  • 1
    Electronic Resource
    Electronic Resource
    Photosynthetic rates in relation to leaf phosphorus content in pioneer versus climax tropical rainforest trees (1995)
    Springer
    Oecologia 102 (1995), S. 120-125 
    Details
    ISSN: 1432-1939
    Keywords: Climax tree species ; Phosphorus Photosynthesis ; Pioneer tree species ; Tropical rainforest
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Guyana dense rainforest occurs on intensely weathered acid soils, low in soil phosphorus. To investigate whether low P availability limits photosynthesis of trees growing on these soils more than N does, leaf P and N content, and their relationship with the photosynthetic capacity (A sat, μmol CO2 m-2 s-1) were studied for nine pioneer and climax tree species in a range of light climates. Light environment was described using hemispherical photographs. For both pioneer and climax species, leaf P content (r 2=0.71 and 0.23, respectively) is a more important determinant of A sat than leaf N content (r 2=0.54 and 0.12, respectively). Pioneer species have a higher leaf P and N content than climax species. At similar P or N content, pioneers have a higher A sat than climax species. The saplings studied had a relatively high A sat, considering their low P concentration (15–30 μmol P g-1). All species studied had a constant leaf P and N concentration and photosynthetic capacity across light climates, because specific leaf mass (g m-2) increased similarly with light availability. This acclimation to a change in light environment makes a possible limitation of A sat by P or N independent of light environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00333319
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The relation between above- and belowground biomass allocation patterns and competitive ability (1991)
    Springer
    Oecologia 87 (1991), S. 551-559 
    Details
    ISSN: 1432-1939
    Keywords: Competition ; Allocation ; Canopy structure ; Rooting pattern ; Plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In a 2-year experiment, the evergreen shrubsErica tetralix andCalluna vulgaris (dominant on nutrient-poor heathland soils) and the perennial deciduous grassMolinia caerulea (dominant on nutrient-rich heathland soils) were grown in replacement series in a factorial combination of four competition types (no competition, only aboveground competition, only belowground competition, full competition) and two levels of nutrient supply (no nutrients and 10 g N+2 g P+10 g K m−2 yr−1). Both in the unfertilized and in the fertilized treatmentsMolinia allocated about twice as much biomass to its root system than didErica andCalluna. In all three species the relative amount of biomass allocated to the roots was lower at high than at low nutrient supply. The relative decrease was larger forMolinia than forErica andCalluna. In the fertilized monocultures biomass of all three species exceeded that in the unfertilized series.Molinia showed the greatest biomass increase. In the unfertilized series no effects of interspecific competition on the biomass of each species were observed in either of the competition treatments. In the fertilized mixtures where only belowground competition was possibleMolinia increased its biomass at the expense of bothErica andCalluna. When only aboveground competition was possible no effects of interspecific competition on the biomass of the competing species were observed. However, in contrast with the evergreens,Molinia responded by positioning its leaf layers relatively higher in the canopy. The effects of full competition were similar to those of only belowground competition, so in the fertilized series belowground competition determined the outcome of competition. The high competitive ability ofMolinia at high nutrient supply can be attributed to the combination of (1) a high potential productivity, (2) a high percentage biomass allocation to the roots, (3) an extensive root system exploiting a large soil volume, and (4) plasticity in the spatial arrangement of leaf layers over its tall canopy. In the species under study the allocation patterns entailed no apparent trade-off between the abilities to compete for above- and belowground resources. This study suggests that this trade-off can be overcome by: (1) plasticity in the spatial arrangement of leaf layers and roots, and (2) compensatory phenotypic and species-specific differences in specific leaf area and specific root length.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320419
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Phenotypic plasticity in response to nitrate supply of an inherently fast-growing species from a fertile habitat and an inherently slow-growing species from an infertile habitat (1993)
    Springer
    Oecologia 96 (1993), S. 548-554 
    Details
    ISSN: 1432-1939
    Keywords: Biomass allocation ; Nitrogen supply ; Phenotypic plasticity ; Photosynthesis ; Root distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The aim of the present study was to investigate possible differences in plasticity between a potentially fast-growing and a potentially slow-growing grass species. To this end, Holcus lanatus (L.) and Deschampsia flexuosa (L.) Trin., associated with fertile and infertile habitats, respectively, were grown in sand at eight nitrate concentrations. When plants obtained a fresh weight of approximately 5 g, biomass allocation, specific leaf area, the rate of net photosynthesis, the organic nitrogen concentration of various plant parts and the root weight at different soil depths were determined. There were linear relationships between the morphological and physiological features studied and the In-transformed nitrate concentration supplied, except for the specific leaf area and root nitrogen concentration of H. lanatus, which did not respond to the nitrate concentration. The root biomass of H. lanatus was invariably distributed over the soil layers than that of D. flexuosa. However, D. flexuosa allocated more root biomass to lower soil depths with decreasing nitrate concentration, in contrast to H. lanatus, which did not respond. The relative response to nitrate supply, i.e. the value of a character at a certain nitrate level relative to the value of that character at the highest nitrate supply, was used as a measure for plasticity. For a number of parameters (leaf area ratio, root weight ratio, root nitrogen concentration, vertical root biomass distribution and rate of net photosynthesis per unit leaf weight) the potentially slow-growing D. flexuosa exhibited a higher phenotypic plasticity than the potentially fast-growing H. lanatus. These findings are in disagreement with current literature. Possible explanations for this discrepancy are discussed in terms of differences in experimental approach as well as fundamental differences in specific traits between fast- and slow-growing grasses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00320512
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Characterization of glucocerebrosidase in Greek Gaucher disease patients: mutation analysis and biochemical studies (1995)
    Springer
    Journal of inherited metabolic disease 18 (1995), S. 609-615 
    Details
    ISSN: 1573-2665
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Gaucher disease is the most frequent lysosomal storage disease in Greece, accounting for 24% of all lysosomal disorders diagnosed during the last 13 years at the Institute of Child Health in Athens. The nature of the defects in glucocerebrosidase in Greek Gaucher patients with non-neuronopathic (type 1) and neuronopathic (types 2 and 3) phenotypes was investigated at the level of the glucocerebrosidase gene and enzyme activity. Mutation analysis performed in 10/23 Gaucher patients with different types of the disorder led to the identification of four mutations, N370S, L444P, R463C and D409H, comprising 75% of the investigated alleles. N370S was only found in association with type 1 disease. The genotype D409H/R463C was identified for the first time and was associated with the severe type 2 disorder. There was no correlation between residualin vitro enzyme activity and either phenotype or genotype. However, in cultured fibroblasts of the neuronopathic cases, glucocerebrosidase protein concentration was reduced and the capacity to degrade exogenous C6NBD-glucosylceramide was more severely impaired.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436006
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    Paper (German National Licenses)
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