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  • 1
    Electronic Resource
    Electronic Resource
    ESTIMATED POPULATION SIZE OF THE CALIFORNIA GRAY WHALE (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Marine mammal science 9 (1993), S. 0 
    Details
    ISSN: 1748-7692
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 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%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1748-7692.1993.tb00452.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Manual recording of minirhizotron data and its application to study the effect of herbicide and nitrogen fertiliser on tree and pasture root growth in a silvopastoral system (1994)
    Springer
    Agroforestry systems 26 (1994), S. 75-87 
    Details
    ISSN: 1572-9680
    Keywords: borescope ; competition ; herbicide ; minirhizotron ; pasture ; Prunus avium ; silvopastoral
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00707007
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Distribution of soil invertase in relation to the root systems ofPicea sitchensis (Bong.) Carr. andAcer pseudoplatanus L. during development of young plants (1994)
    Springer
    Plant and soil 167 (1994), S. 73-77 
    Details
    ISSN: 1573-5036
    Keywords: Acer ; invertase ; Picea ; rhizosphere ; roots ; statistics ; trees
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01587601
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of nitrogen on fine white root persistence in cherry (Prunus avium) (1995)
    Springer
    Plant and soil 173 (1995), S. 349-353 
    Details
    ISSN: 1573-5036
    Keywords: borescope ; cherry ; nitrogen ; persistence ; root ; season
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00011474
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  • 5
    Electronic Resource
    Electronic Resource
    A method for counting roots observed in minirhizotrons and their theoretical conversion to root length density (1993)
    Springer
    Plant and soil 153 (1993), S. 1-9 
    Details
    ISSN: 1573-5036
    Keywords: borescope ; minirhizotron ; pasture ; root length density ; silvopastoral ; wild cherry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010539
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    A permutation test for assessing the similarity of ordered sequences (1996)
    Springer
    Mathematical geology 28 (1996), S. 735-742 
    Details
    ISSN: 1573-8868
    Keywords: sequence comparison ; stratigraphical correlation ; permutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02066343
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    Paper (German National Licenses)
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