Journal Article

Annual and spatial variation in shoot demography associated with masting in <i>Betula grossa</i>: comparison between mature trees and saplings

Masae Iwamoto Ishihara and Kihachiro Kikuzawa

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 104, issue 6, pages 1195-1205
Published in print November 2009 | ISSN: 0305-7364
Published online September 2009 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcp217
Annual and spatial variation in shoot demography associated with masting in Betula grossa: comparison between mature trees and saplings

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  • Ecology and Conservation
  • Evolutionary Biology
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Backgrounds and Aims

Shoot demography affects the growth of the tree crown and the number of leaves on a tree. Masting may cause inter-annual and spatial variation in shoot demography of mature trees, which may in turn affect the resource budget of the tree. The aim of this study was to evaluate the effect of masting on the temporal and spatial variations in shoot demography of mature Betula grossa.

Methods

The shoot demography was analysed in the upper and lower parts of the tree crown in mature trees and saplings over 7 years. Mature trees and saplings were compared to differentiate the effect of masting from the effect of exogenous environment on shoot demography. The fate of different shoot types (reproductive, vegetative, short, long), shoot length and leaf area were investigated by monitoring and by retrospective survey using morphological markers on branches. The effects of year and branch position on demographic parameters were evaluated.

Key Results

Shoot increase rate, production of long shoots, bud mortality, length of long shoots and leaf area of a branch fluctuated periodically from year to year in mature trees over 7 years, in which two masting events occurred. Branches within a crown showed synchronized annual variation, and the extent of fluctuation was larger in the upper branches than the lower branches. Vegetative shoots varied in their bud differentiation each year and contributed to the dynamic shoot demography as much as did reproductive shoots, suggesting physiological integration in shoot demography through hormonal regulation and resource allocation.

Conclusions

Masting caused periodic annual variation in shoot demography of the mature trees and the effect was spatially variable within a tree crown. Since masting is a common phenomenon among tree species, annual variation in shoot demography and leaf area should be incorporated into resource allocation models of mature masting trees.

Keywords: Masting; shoot demography; short shoot; long shoot; temporal variation; spatial variation; leaf area; shoot length; resource allocation; Betula grossa

Journal Article.  7200 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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