The relationships between stem length (SL) and leaf display index (LDk the ratio of leaf area to stem length) of current-year shoots are compared for eight deciduous tree species. Two patterns were found in the relationships. In seven species (Amono, Aesculus furbinata, Betula gmsa, Catphs tdnnwskih Fwus emnab, Rerocarya rhoifolia, and Quercus mongolica var.grosseserrata), LDI decreased exponentially with SL, which suggests that short current-year shoots favor leaf-display over space-acquisition, and the reverse for long current-year shoots. The decrease in LDI was much greater and sharper in 8. grossa, which shows apparent differentiation of short and long shoots, than in the other six species, which do not show such differentiation. In another species that shows no differentiation of short and long shoots, Clerodendron tricbotomum, LD/ increased linearly and gradually with SL. This suggests that its long current-year shoots are superior to its short current-year shoots for both spaceacquisition and leaf-display, and that the structural variation in its current-year shoots is small. The diverse patterns in the relationships between SL and LDI of current-year shoots are related to the variations among current-year shoots in the mean leaf number per unit stem length and the mean individual leaf area.

Variations in morphology and biomass allocation of current-year shoots were investigated in saplings of ten cooltemperate tall tree species. In all the species, the ratio (leaf mass)/(stem mass) was greater in shorter current-year shoots than in longer current-year shoots. This indicates the presence of shoot differentiation, where shorter currentyear shoots are oriented to light-capture or leaf-display and longer current-year shoots are oriented to crown-expansion or space-acquisition. However, two types of differentiation were found. In type I, shorter current-year shoots had greater ratios of (leaf area)/(stem length) than longer current-year shoots and a ratio of (stem mass)/(stem length) comparable to that of longer current-year shoots. In type II, shorter current-year shoots had disproportionately smaller ratios of (stem mass)/(stem length) than longer currentyear shoots and a ratio of (leaf area)/(stem length) comparable to that of longer current-year shoots. Type I corresponds to the apparent differentiation of dwarf shoots. Type II was newly found in this study. I hypothesize that shorter current-year shoots in type I have stout stems for supporting offspring shoots in spite of severe self-shading, whereas shorter current-year shoots in type II avoid selfshading at the expense of stout stems. Implications of the two types of shoot differentiation are discussed in relation to foliage-crown dynamics.Key words: Biomass allocation -Frequency distribution of shoot length -Leaf display index -Shoot differentiation -Stem length -Stem mass per unit stem lengthCurrent-year shoots are fundamental units for tree crown development, and the relative importance of light-capture (i.e., leaf-display) and crown-expansion (i.e., space-acquisition) for current-year shoots is not uniform even within a single tree. Therefore, the differentiation of current-year shoots for light-capture or crown-expansion is an effective Present address:Abbreviations: LDI, the ratio of (leaf area)/(stem length) of a currentyear shoot (leaf display index); LSR, the ratio of (leaf mass)/(stem mass) of a current-year shoot (leaf-stem ratio); LSRPo,, the ratio of (total leaf mass)/(total stem mass) of the sampled current-year shoots (be., leaf-stem ratio of a population of current-year shoots) tactic for constructing an efficient assimilation system (Halle et a/, 1978, Steingraeber and Waller 1986, Seino 1998. Crown-expansion is more important than light-capture for current-year shoots facing an open space with high light availability; the opposite is true for current-year shoots in the inner and lower portions of a crown and for current-year shoots facing the crown of neighboring trees (Remphrey et a/. 1983, Borchert and Tomlinson 1984, Jones and Harper 1987. The differentiation of current-year shoots is likely to be universal among tree species.Patterns of differentiation of current-year shoots are closely related to the productive strategies of trees. For example, the total amount of foliage and the leaf-stem balance of an assimilation system...

The relations of leaf–stem balance, stem thickness, leaf thickness, and leaf size to stem length of current-year shoots were compared between terminal and lateral shoots in saplings of 10 tall tree species in a Japanese cool-temperate forest. Six monopodial and four substitution sympodial branching species were studied. For both terminal and lateral shoots, the ratios of leaf area / stem length, leaf mass / stem mass, and leaf number / stem length were greater in shorter current-year shoots, implying shoot differentiation such that short current-year shoots specialize in leaf display and long current-year shoots in crown expansion. These ratios were generally greater for terminal shoots than for lateral shoots, especially in the lower range of stem length. This tendency was more conspicuous in the ratio leaf area / stem length than in leaf mass / stem mass and leaf number / stem length, because terminal shoots showed greater stem mass / stem length, leaf area / leaf mass, and leaf area / leaf number ratios than lateral shoots. These terminal–lateral variations were generally greater in the monopodial species than in sympodial species. These observations are discussed in relation to differences in ecological functions and hydraulic architecture between terminal and lateral shoots, and in relation to apical control and branching patterns (the monopodium and the sympodium).Key words: shoot functions, apical control, short shoots, terminal shoots, monopodial branching, substitution sympodial branching.

Ontogenetic architectural variation is a key aspect of the light foraging of saplings under canopy gaps, where the interactions with the surrounding understorey plants are intense and change as saplings grow. Therefore, relationships between the allometry of 58 Fagus saplings (15-184 cm tall) and both the surrounding vegetation and light environment were investigated in the dense understorey of canopy gaps. The light available to the saplings exhibited a positive exponential relationship to their height, and at a given sapling height, it was inversely related to the height of the surrounding understorey. The slenderness of the saplings' stems increased as their height increased, and their crown architecture shifted from horizontally spread monolayer to vertically extended multilayer forms, indicating an ontogenetic strategy shift from shade tolerance to shade avoidance. These changes in sapling architecture were independent of the height of the surrounding understorey and, therefore, light availability, although the length of their current-year shoots (reflecting the rate of architectural development) was inversely related to the surrounding understorey height. Thus, ontogenetic architectural variation in Fagus saplings probably has the character of a developmentally programmed growth trajectory preadjusted to the most likely environments; the surrounding environments mainly affect the rate at which saplings move along this trajectory.Résumé : La variation architecturale ontogénétique est un aspect clé de la recherche de la lumière pour les semis situés dans des trouées de la canopée où les interactions avec les plantes de sous-bois environnantes sont intenses et changent à mesure que croissent les semis. Ainsi, les relations entre l'allométrie de 58 semis de Fagus (de 15 à 184 cm de hauteur), d'une part, et la végétation environnante et les conditions lumineuses, d'autre part, ont été étudiées dans la végétation dense du sous-bois de trouées dans la canopée. La lumière disponible pour les semis augmentait de façon exponentielle avec leur hauteur et, pour une hauteur donnée des semis, elle était inversement reliée à la hauteur de la végétation de sous-bois environnante. L'élancement de la tige des semis augmentait avec leur hauteur et l'architecture de leur cime passait d'une forme monoétagée s'étendant horizontalement à une forme multiétagée s'étendant verticalement, ce qui indique un changement de stratégie ontogénétique allant de la tolérance à l'ombre à l'évitement de l'ombre. Ces changements de l'architecture des semis étaient indépendants de la hauteur de la végétation de sous-bois environnante et, par conséquent, de la disponibilité de la lumière, même si la longueur des pousses de l'année courante (reflétant le taux de développement architectural) était inversement reliée à la hauteur de la végétation de sous-bois environnante. Par conséquent, la variation ontogénétique architecturale des semis de Fagus adopte probablement une trajectoire de croissance dont le développement est programmé et qui est préaju...

2016 Correlation between Height:diameter Ratio and Shoot Growth in Containerised and Bare-root Seedlings of Cryptomeria japonica. J Jpn For Soc 98: 139 145 Previous studies revealed that in terms of the stem height growth, containerised seedlings with an average height:diameter ratio HDR of ca. are superior to conventional bare-root seedlings and containerised seedlings with an average HDR of ca. are inferior to conventional bare-root seedlings. In this study, we focused on the correlation between the stem growth and HDR in individual seedlings. We measured the stem growth of-year-old containerised seedlings and-year-old conventional bare-root seedlings for four growth seasons. In each of the growth seasons, HDR showed a negative correlation with stem height growth rate and a positive correlation with the stem radial growth rate of an individual seedling; the strongest correlation was observed in the first and second growth seasons. Therefore, the seedling with a high HDR allocated resources to stem radial growth rather than to height growth. Regarding the stem height growth, we analysed the sequential data for four growth seasons using a linear mixed effects model. HDR showed a negative correlation with the stem height growth. In conclusion, high HDR had negative effects on not only the relative height growth rate but also on the actual height growth.