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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 90 (1992), S. 429-434 
    ISSN: 1432-1939
    Keywords: Competition ; Methods ; Size ; Substitutive experiment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The objective of this study was to examine the claim that traditional measures of competitive performance in substitutive experiments are biased towards larger plants. Results from a three-year diallele experiment of 6 marsh plant species were analyzed using both Relative Yields (a traditional analysis) and the Relative Efficiency Index (a recently proposed analysis presumed to be size-independent). In adddition, a mechanistic model of competition was used to explore the behavior of both methods of estimating competitive performance. Results from the three-year experiment showed that Relative Yields (RYs) were correlated with the initial sizes of plants for the first two years but not the third. By the third year, RYs were highly correlated with Relative Efficiency Index values (REIs) suggesting that the effects of initial size were eventually overcome. Model results showed that RYs are inherently biased in favor of larger plants during the early phases of competition while REIs are not. Further, model analysis confirmed that the size bias associated with RYs declines with increasing duration of the experiment. It is concluded that current generalizations about the relationship between plant size and competitive ability may be biased by the procedures used to analyze competition experiments.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-9761
    Keywords: disturbance ; fire ; heterogeneity ; landscape pattern ; topography ; Wisconsin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The presettlement tree cover (1831–33) of 3 townships in a southern Wisconsin landscape was analyzed using original survey records. Four forest types were identified: closed forest, open forest, savanna, and prairie. Comparisons of vegetation types and landscape pattern were made between the east and west sides of the Pecatonica River, which bisects the landscape and could have acted as a natural fire barrier. West of the river, presettlement tree species richness and diversity were lower and trees were smaller in diameter and less dense than to the east. The major vegetation types to the west were prairie (42% of landscape) and savanna (40%), both fire-susceptible types. Prairie was more common on gentle slopes than on other landforms. To the east, the landscape was 70% forested (closed plus open forest). Here, prairie was more frequent on steep dry sites. These vegetation differences, including the contrasting landscape placement of prairie, are attributed to distinct site characteristics and to disturbance (fire) regimes, with the west likely having more frequent fires. In terms of the four vegetation types, the east landscape was more homogeneous, being dominated by closed forest (50%). West of the Pecatonica River, the landscape was more heterogeneous because of the high proportion of both prairie and savanna; however, in terms of flammability of vegetation, the west was essentially homogeneous (82% prairie plus savanna).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Urban ecosystems 2 (1998), S. 187-188 
    ISSN: 1573-1642
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering
    Type of Medium: Electronic Resource
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