title: Reproduction-related variation in carbon allocation to woody tissues in Fagus crenata using a natural 13C approach.
abstract: The contribution of new photo-assimilates and stored carbon (C) to plant growth remains poorly understood, especially during reproduction. In order to elucidate how mast seeding affects C allocation to both reproductive and vegetative tissues, we measured biomass increase in each tissue, branch starch concentration and stable C isotope composition (δ13C) in bulk leaves, current-year shoots, 3-year branches and tree rings in fruiting and non-fruiting trees for 2 years, as well as in fruits. We isolated the effect of reproduction on C allocation to vegetative growth by comparing13C enrichment in woody tissues in fruiting and non-fruiting specimens. Compared with 2‰13C enrichment in shoots relative to leaves from non-fruiting trees, fruiting reduced the enrichment to 1‰ and this reduction disappeared in the following year with no fruiting, indicating that new photo-assimilates are preferentially used for woody tissues even with fruiting burden. In contrast, fruits had up to 2.5‰13C enrichment at mid-summer, which dropped thereafter, indicating that fruit production relies on C storage early in the growing season then shifts to current photo-assimilates. At this tipping point, growth of shoots and cupules had almost finished and nuts had a second rapid growth period thereafter. Together with shorter shoots but higher biomass increment per length in fruiting trees than non-fruiting trees, these results indicate that the C limitation due to fruit burden is minimized by fine-tuning of allocation of old C stores and new photo-assimilates, along with the growth pattern in various tissues. Furthermore, fruiting had no significant effect on starch concentration in 3-year-old branches, which became fully depleted during leaf and flower flushing but were quickly replenished. These results indicate that reproduction affects C allocation to branches but not its source or storage. These reproduction-related variations in the fate of C have implications for evaluating forest ecosystem C cycles during climate change.
authors: Hokkaido Research Center, Forestry and Forest Products Research Institute (FFPRI), 7 Hitsujigaoka, Toyohira, Sapporo, Hokkaido 062-8516, Japan qhan@ffpri.affrc.go.jp.|Department of Plant Ecology, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan.
authors: Qingmin
authors: Q
authors: Han
authors: Department of Wood Properties, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan.
authors: Akira
authors: A
authors: Kagawa
authors: Department of Plant Ecology, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan.
authors: Daisuke
authors: D
authors: Kabeya
authors: Department of Forest Site Environment, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan.|Present address: Shikoku Research Center, FFPRI, 2-915 Asakuranishi, Kochi, 780-8077, Japan.
authors: Yoshiyuki
authors: Y
authors: Inagaki
mesh_terms: D002244:Carbon / Q000378:metabolism*; D002247:Carbon Isotopes; D029964:Fagus / Q000254:growth & development / Q000378:metabolism*; D007564:Japan; D012098:Reproduction; D012621:Seasons; D014197:Trees / Q000254:growth & development / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D002244:Carbon
keywords: 
  13C; allocation; carbohydrate; growth; masting; starch; storage; tree ring