Photosynthesis and biomass allocation of beech (Fagus crenata) and dwarf-bamboo (Sasa kurilensis) in response to contrasting light regimes in a Japan Sea-Type beech forest |
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| Authors: | Tsuyoshi Kobayashi Hiroyuki Muraoka Koji Shimano |
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| Institution: | (1) Laboratory of Ecology, Department of Environmental Sciences, Faculty of Science, Ibaraki University, 310-8512 Mito, Japan;(2) Institute of Biological Sciences, University of Tsukuba, 305-8572 Tsukuba, Japan;(3) Department of Vegetation Ecotechnology, Institute of Environmental Science and Technology, Yokohama National University, 240-8501 Yokohama, Japan;(4) Present address: Japan Science and Technology Corporation, The Center for Forest Decline Studies, Hiroshima Technoplaza, 3-13-26, Kagamiyama, 739-0046 Higashi-Hiroshima, Japan;(5) Present address: Institute for Basin Ecosystem Studies, Gifu University, 501-1193 Yanagido, Gifu, Japan |
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| Abstract: | Regeneration of beech (Fagus crenata) forests depends on the formation of canopy gaps. However, in Japan Sea-type beech forests, a dwarf bamboo (Sasa kurilensis) conspicuously occupies sunny gaps. Therefore,F. crenata seedlings must escape the severe interference ofS. kurilensis in the gaps and persist beneath a closed canopy of the beech forest. We hypothesized that the growth ofF. crenata seedlings in the understory would be favored by their being more plastic thanS. kurilensis in photosynthetic and morphological traits, which would support the matter production ofF. crenata seedlings in a wide range of light availabilities. To examine this hypothesis, the photosynthetic-light response of individual
leaves and the biomass allocation in aboveground parts (i.e., the culm/foliage ratio) were surveyed at sites with contrasting light availabilities in a Japan Sea-type beech forest in
central Japan. InF. crenata, photosynthetic light utilization efficiency at relatively low light was greater, and the dark respiration rate was smaller
in the leaves of seedlings (10 cm in height) beneath the closed canopy than in the leaves of saplings at the sunny forest
edge. The culm/foliage (C/F) ratio of theF. crenata seedlings at the shady site was small, suggesting effective matter-production beneath the beech canopy. On the other hand,S. kurilensis both in the gap and beneath the beech canopy showed low plasticity in photosynthesis and the culm/foliage ratio. Because
the shoot density ofS. kurilensis was smaller beneath the beech canopy than in the gap, the light availability at the bottom of theS. kurilensis layer was greater beneath the beech canopy. These results suggest that the photosynthetic productivity of theF. crenata seedlings would be enough for the seedlings to survive in the understory with a low density ofS. kurilensis shoots beneath the closed beech canopy. |
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| Keywords: | canopy C/F ratio gap plasticity seedling |
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