Individual resource allocation to vegetative growth and reproduction in subgenus <Emphasis Type="Italic">Cyclobalanopsis</Emphasis> (<Emphasis Type="Italic">Quercus</Emphasis>, Fagaceae) trees |
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Authors: | Daisuke Hirayama Satoshi Nanami Akira Itoh Takuo Yamakura |
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Institution: | (1) Laboratory of Plant Ecology, Graduate School of Science, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan |
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Abstract: | The resource allocation for vegetative growth and female reproduction in three tree species of subgenus Cyclobalanopsis (Quercus, Fagaceae), i.e., Q. salicina, Q. sessilifolia, and Q. acuta, were examined on a per-individual basis in two consecutive reproductive seasons, in order to test whether these trees fit
the predictions of the masting hypotheses about resource matching versus resource switching. Since the three Quercus species have a biennial fruiting habit, it takes 3 years for the observation of two reproductive events. Female flower and
acorn production per tree were investigated by using a seed-trap method and a numerical analysis of seed dispersal. The net
production of each individual was estimated as the sum of the annual increase in the dry mass of vegetative organs and reproductive
investment per tree. In the data analyses, the three species were pooled, since all 12 sample trees of the subgenus apparently
showed masting in the same year, with no exceptions. Female flower and acorn production per individual tree changed considerably
between years. The net production per tree increased with tree size, but did not differ between years. Therefore, the reproductive
allocation (proportion of a plant’s annual assimilated resources which are used for reproduction) differed dramatically between
years. On the other hand, within a year, the reproductive allocation increased with increasing net production per tree. These
results suggest that the switching of resource allocation between years within an individual are occurring in subgenus Cyclobalanopsis species, and the intensity of the switching increases with increasing tree size. |
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Keywords: | Acorn production Reproductive allocation Switching Seed trap Subgenus Cyclobalanopsis |
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