Removing Biological Trends from Tree-Ring Series: Testing Modified Hugershoff Curves

• Autores: Keyan Fang
• Localización: Tree-ring research, ISSN 1536-1098, Vol. 66, nº. 1, 2010, págs. 51-59
• Idioma: inglés
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• Resumen

  • The performance of the Hugershoff curve on fitting the growth trends of tree-ring series was tested using ring-width series with different starting years. The fitted values tend to be biased by tree-ring series close to pith, a phenomenon that was referred to as the �start-fitting problem�. We determined three parameters with specific biological age-related meanings for the Hugershoff growth curve, i.e. the maximum growth, the maximum slope and the maximum changing ratio of slopes. A set of modified Hugershoff curves with different starting years was proposed to mitigate the start-fitting problem. Behavior of the modified Hugershoff curves on tree-ring series standardizations was tested and discussed. The �end-fitting problem� suggests that deviations in one interval could bias the fitted values of other time periods by using the Hugershoff curve.