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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 9 (1993), S. 0 
    ISSN: 1748-7692
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract: The 1987-1988 counts of gray whales passing Monterey are reanalyzed to provide a revised population size estimate. The double count data are modeled using iterative logistic regression to allow for the effects of various covariates on probability of detection, and a correction factor is introduced for night rate of travel. The revised absolute population size estimate is 20,869 animals, with CV = 4.37% and 95% confidence interval (19,200, 22,700). In addition the series of relative population size estimates from 1967-1968 to 1987-1988 is scaled to pass through this estimate and modeled to provide variance estimates from interannual variation in population size estimates. This method yields an alternative population size estimate for 1987-1988 of 21,296 animals, with CV = 6.05% and 95% confidence interval (18,900, 24,000). The average annual rate of increase between 1967-1968 and 1987-1988 was estimated to be 3.29% with standard error 0.44%.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1572-9680
    Schlagwort(e): borescope ; competition ; herbicide ; minirhizotron ; pasture ; Prunus avium ; silvopastoral
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The use of a simple counting method using a borescope and minirhizotron system to study the interaction of roots of wild cherry trees (Prunus avium L) and pasture in an upland silvopastoral system is described. Operator variation was greatest when distinguishing different tree root categories (e.g. white, brown, woody) but was not significant in relation to total tree or grass root counts or species differences. Analysis of covariance was used to take these differences into account in a field trial using several operators. The seasonal patterns of tree and pasture root growth were different. Tree roots peaked in May before maximal shoot growth. The peak in pasture roots occurred two weeks earlier. Tree height growth was increased by the use of herbicides to control grass growth but this effect was only apparent during August when the soil was dry and when pasture root counts were reduced.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1573-5036
    Schlagwort(e): Acer ; invertase ; Picea ; rhizosphere ; roots ; statistics ; trees
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A method is described for sampling rhizosphere soil under newly establishedPicea sitchensis andAcer pseudoplatanus. The technique involves taking soil samples to a depth of 150 mm at 100 mm intervals along transects, each 45° from its neighbour, radiating from the base of the stem. Invertase activities were measured in the soil samples and compared to their activities in fallow and rhizosphere soils. When the field soil was dry, the tree root systems were carefully excavated to retain as many fine roots as possible. The distribution of the soil invertase was matched to the spatial distribution of the roots showing the precise position of the rhizosphere relative to the initial ‘blind’ soil sampling. Statistics were applied to derive equations for calculating the percentage enzyme activity relative to that found in rhizosphere soil at various locations radiating from the base of the stem. This information was subsequently applied to soil sampled under trees of the same age as those excavated to give a non-destructive method for sampling rhizosphere soil routinely from under a large number of trees.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Plant and soil 173 (1995), S. 349-353 
    ISSN: 1573-5036
    Schlagwort(e): borescope ; cherry ; nitrogen ; persistence ; root ; season
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract The persistence of white roots in cherry (Prunus avium) grown under two levels of nitrogen (high and low), was studied directly using a non-destructive borescope system. Plant growth and nitrogen uptake was increased by the extra nitrogen. Persistence times of white roots were significantly affected by several factors such as nitrogen level, time of appearance and depth in the pot. Suberisation of white roots tended to be late in the growing season, and roots produced in the middle of May persisted as white for significantly longer (5.9 weeks) than those produced in early July (2.5 weeks). Also, roots that appeared at the foot of the pot remained white for longer (5.6 weeks) than roots at the surface of the pot (2.7 weeks). Results also suggest that white root persistence was greater for trees with the lower rate of application of nitrogen (4.5 weeks under low nitrogen compared to 3.6 under high nitrogen).
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1573-5036
    Schlagwort(e): borescope ; minirhizotron ; pasture ; root length density ; silvopastoral ; wild cherry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A method for counting root intersections with observation tubes (mini- or micro-rhizotrons) is proposed that allows a theoretical conversion of root counts to estimated root length density and which is robust to the effects of tracking along the tubes. A field test showed that the method agreed well with measured root length densities in cores for wild cherry roots but not for roots of pasture species. The circumstances in which the method might be expected to perform well are discussed. Analysis of data from a field trial revealed that root counts were not uniformly distributed around the circumference of the observation tube. Implications for the design of such trials are noted.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Mathematical geology 28 (1996), S. 735-742 
    ISSN: 1573-8868
    Schlagwort(e): sequence comparison ; stratigraphical correlation ; permutation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie , Mathematik
    Notizen: Abstract This paper presents a permutation test to assess whether the observed similarity between ordered sequences could have arisen by chance, illustrating the methodology by application to geophysical logs.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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