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| Koyama, Kohei; Kikuzawa, Kihachiro. |
| Light absorption and use efficiency (LAUE mol mol−1, daily gross photosynthesis per daily incident light) of each leaf depends on several factors, including the degree of light saturation. It is often discussed that upper canopy leaves exposed to direct sunlight are fully light-saturated. However, we found that upper leaves of three temperate species, a heliophytic perennial herb Helianthus tuberosus, a pioneer tree Alnus japonica, and a late-successional tree Fagus crenata, were not fully light-saturated even under full sunlight. Geometrical analysis of the photosynthetic light response curves revealed that all the curves of the leaves from different canopy positions, as well as from the different species, can be considered as different parts of a single... |
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Palavras-chave: Scaling; Big leaf model; Helianthus tuberosus; Alnus japonica; Fagus crenata. |
| Ano: 2010 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/4482 |
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| Koyama, Kohei; Yamamoto, Ken; Ushio, Masayuki. |
| Lognormal distributions and self-similarity are characteristics associated with a wide range of biological systems. The sequential breakage model has established a link between lognormal distributions and self-similarity and has been used to explain species abundance distributions. To date, however, there has been no similar evidence in studies of multicellular organismal forms. We tested the hypotheses that the distribution of the lengths of terminal stems of Japanese elm trees (Ulmus davidiana), the end products of a self-similar branching process, approaches a lognormal distribution. We measured the length of the stem segments of three elm branches and obtained the following results: (i) each occurrence of branching caused variations or errors in the... |
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Palavras-chave: Allometry; Fractal; Phenotypic plasticity; Shoot size; Stochastic process; WBE theory. |
| Ano: 2017 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/4577 |
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| Koyama, Kohei; Kikuzawa, Kihachiro. |
| We investigated the leaf demography of a temperate woody liana, Akebia trifoliata, in a temperate forest in Japan, Akebia is semi-evergreen: some leaves are shed before winter, while others remain through the winter. Previous studies of semi-evergreen species found that variation in leaf life span was caused by variation in the timing of leaf emergence, Leaves that appeared just before winter over-wintered, while leaves appearing earlier were shed, However, it is unclear whether leaves of the same cohort (i.e., leaves that appear at the same time within a single site) show variation in life span under the effect of strong seasonality. To separate variation in life span among the leaves in each cohort from variation among cohorts, we propose a new method -... |
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Palavras-chave: Akebia trifoliata; Leaf demography; Leaf lifespan; Leaf phenology; Liana; Phenotypic plasticity; Semi-evergreen. |
| Ano: 2016 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/4523 |
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| Koyama, Kohei; Hidaka, Yoshiki; Ushio, Masayuki. |
| We investigated whole-plant leaf area in relation to ontogenetic variation in leaf-size for a forest perennial herb, Cardiocrinum cordatum. The 200-fold ontogenetic variability in C. cordatum leaf area followed a power-law dependence on total leaf number, a measure of developmental stage. When we normalized for plant size, the function describing the size of single leaves along the stem was similar among different-sized plants, implying that the different-sized canopies observed at different times in the growth trajectory were fundamentally similar to each other. We conclude that the growth trajectory of a population of C. cordatum plant leaves obeyed a dynamic scaling law, the first reported for a growth trajectory at the whole-plant level. |
| Ano: 2012 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/4525 |
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| Koyama, Kohei; Kikuzawa, Kihachiro. |
| It has been well established that leaf longevity is linked to the carbon economy of plants. We used this relationship to predict leaf lifetime carbon gains from leaf lifespan, and estimated the gross primary production (GPP) of a young deciduous forest of Japanese beech (Fagus crenata) located in central Japan. The light-saturated photosynthetic rates of the leaves were measured repeatedly during the growing season. We used the leaf lifespan to calculate the conversion coefficient from the light-saturated photosynthetic rate into the realized leaf lifetime carbon gain under field conditions. The leaf turnover rate was estimated using litter traps. GPP was estimated as the product of lifetime carbon gain per unit of leaf mass, and the annual leaf turnover... |
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Palavras-chave: Fagus crenata; Functional leaf longevity; Gross primary production; Mean labor time; Temperate forest. |
| Ano: 2016 |
URL: http://ir.obihiro.ac.jp/dspace/handle/10322/4524 |
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