AOBPreview originally published online on September 3, 2009
Annals of Botany 2009 104(6):1195-1205; doi:10.1093/aob/mcp217
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Annual and spatial variation in shoot demography associated with masting in Betula grossa: comparison between mature trees and saplings
Laboratory of Forest Biology, Graduate School of Agriculture, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan
* For correspondence. Present address: Tomakomai Research Station, Field Science Center for Northern Biosphere, Hokkaido University, Tomakomai, 053-0035, Japan. E-mail: masaish{at}fsc.hokudai.ac.jp
Received: 23 April 2009 Returned for revision: 1 June 2009 Accepted: 24 July 2009 Published electronically: 3 September 2009
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.
Key words: Masting, shoot demography, short shoot, long shoot, temporal variation, spatial variation, leaf area, shoot length, resource allocation, Betula grossa
Present address: Department of Environmental Science, Ishikawa Prefectural University, Nonoichi, Ishikawa, 921-8836, Japan
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