Yoshitaka Kakubari - Academia.edu (original) (raw)

Papers by Yoshitaka Kakubari

Research paper thumbnail of Photosynthetic Responses to Lightflecks of Fagus crenata Seedlings Grown in a Gap and Understory of a Deciduous Forest

Journal of Forest Research, Nov 16, 2002

Research paper thumbnail of Significance of afforestation of desert and its evaluation as a countermeasure against carbon dioxide problem

Energy Conversion and Management, Sep 30, 1995

The surface plant is thought to be one of the most feasible final sinks.

Research paper thumbnail of Temperature Control of SMA Artificial Sphincter Utilizing Thermosensitive Magnetic Ferrite Transformer

Journal of the Magnetics Society of Japan, 2003

Research paper thumbnail of ROLES OF PROLINE IN OSMOTIC STRESS TOLERANCE AND MORPHOGENESIS OF Arabidopsis

Plant and Cell Physiology, May 1, 1998

Research paper thumbnail of Soil organic carbon stock is closely related to aboveground vegetation properties in cold-temperate mountainous forests

Geoderma, Jan 15, 2010

The soils of cold-temperate mountainous forest ecosystems contain large carbon pools that may res... more The soils of cold-temperate mountainous forest ecosystems contain large carbon pools that may respond quickly to changes in climate and land use. A better understanding of the temporal-spatial distribution of soil organic carbon (SOC) stock is the first step toward quantifying its potential responses to global changes in climate or land use. The primary objective of this study was to understand the spatial distribution of SOC within a representative mountainous landscape in the cold-temperate zone in Japan. The two dominant tree species in this region are beech (Fagus crenata, a climax species in this zone), and birch (Betula ermanii). In 15 permanent plots located along an altitudinal gradient on the Mount Naeba and Mount Yakio, relationships were determined between SOC and climate (as represented by mean annual temperature), topography (aspect, slope, and altitude), aboveground vegetation properties (stand age, leaf area index, aboveground biomass, mean tree height, tree diameter, stand density, tree basal area, litter depth, and site index), and soil properties (soil bulk density, soil hardness, soil water content, soil root content). Our results indicated that SOC stocks in Japanese cold-temperate forest ecosystems are relatively high, ranging from 12 to 20 kg m − 2 in the top 30 cm of soils. Correlation analysis that included data from all 15 plots (and therefore data from both beech and birch forest and both mountains) suggested that the aboveground vegetation properties, such as aboveground biomass, mean tree height, and stand density, were strongly correlated with the SOC stock. In contrast, topographic factors (aspect and slope) explained SOC spatial distribution for the plots within the same mountain but not for plots from both mountains. Regression models based only on aboveground vegetation properties explained 76.7% of the variability in SOC stocks in beech ecosystems (represented by 10 plots) and 74.9% of the variability in all 15 plots. The strong correlation between aboveground vegetation properties and SOC suggests that measurement of vegetation properties by remote sensing could represent a feasible and rapid method for estimating SOC distribution in a rugged terrain.

Research paper thumbnail of The influence of previous irradiance on photosynthetic induction in three species grown in the gap and understory of a Fagus crenata forest

Photosynthetica, 2001

ABSTRACT

Research paper thumbnail of Spatial and Seasonal Variations in Photosynthetic Properties within a Beech (Fagus crenata Blume) Crown

Journal of Forest Research, Feb 16, 1999

Research paper thumbnail of Temperature Control of SMA Artificial Sphincter Utilizing Thermosensitive Magnetic Ferrite Transformer

Journal of The Magnetics Society of Japan, 2003

Research paper thumbnail of Masting affected intra- and inter-annual variations in stored nitrogen reserves in _Fagus crenata_ trees

Background / Purpose: We tested nitrogen depletion hypothesis in mature Fagus crenata trees by tr... more Background / Purpose: We tested nitrogen depletion hypothesis in mature Fagus crenata trees by tracing seasonal and inter-annual variation in branches, stems and roots for five years, which included three masting events. Main conclusion: Branches served as the main organ for mobile nitrogen storage in Fagus crenata. Although the individual nitrogen storage had both seasonal and interannual variations, it is unlikely that nitrogen storage threshold is the trigger of mast seeding as assumed in the resource budget model.

Research paper thumbnail of Examination of Phase Excitation in a Desktop CLPS

Journal of the Magnetics Society of Japan, 2009

Research paper thumbnail of Diurnal and Seasonal Courses of Photosynthesis, Transpiration and Water Use Efficiency of Apple and Black Locust Seedlings in Different Soil Water Conditios

Journal of the Japanese Society of Revegetation Technology, 1995

Research paper thumbnail of Vertical, horizontal and azimuthal variations in leaf photosynthetic characteristics within a Fagus crenata crown in relation to light acclimation

Tree physiology, 2005

An understanding of spatial variations in gas exchange parameters in relation to the light enviro... more An understanding of spatial variations in gas exchange parameters in relation to the light environment is crucial for modeling canopy photosynthesis. We measured vertical, horizontal and azimuthal (north and south) variations in photosynthetic capacity (i.e., the maximum rate of carboxylation: Vcmax), nitrogen content (N), leaf mass per area (LMA) and chlorophyll content (Chl) in relation to relative photosynthetic photon flux (rPPF) within a Fagus crenata Blume crown. The horizontal gradient of rPPF was similar in magnitude to the vertical gradient of rPPF from the upper to the lower crown. The rPPF in the north quadrant of the crown was slightly lower than in the south quadrant. Nitrogen content per area (Narea), LMA and Vcmax were strictly proportional to rPPF, irrespective of the vertical direction, horizontal direction and crown azimuth, whereas nitrogen content per dry mass, Chl per area and photosynthetic capacity per dry mass (Vm) were fairly constant. Statistical analyses s...

Research paper thumbnail of Photosynthetic acclimation to dynamic changes in environmental conditions associated with deciduous overstory phenology in Daphniphyllum humile, an evergreen understory shrub

Tree physiology, 2005

Photoprotective responses during photosynthetic acclimation in Daphniphyllum humile Maxim, an eve... more Photoprotective responses during photosynthetic acclimation in Daphniphyllum humile Maxim, an evergreen understory shrub that grows in temperate deciduous forests, were examined in relation to changes in light availability and temperature caused by the seasonal dynamics of canopy leaf phenology. Gradual increases in irradiance in the understory from summer to autumn as overstory foliage senesced were accompanied by increased concentrations of xanthophyll cycle pigments (VAZ) in understory leaves. The chlorophyll (Chl) a/b ratio in understory leaves also increased from summer to autumn, reflecting the change in ratio of the light-harvesting antenna to the reaction center. However, low temperatures following overstory leaf fall reduced Rubisco activity. In contrast, the photosynthetic capactiy of leaves of D. humile growing at the forest border, which was higher in summer than that of leaves of understory plants, decreased in autumn. In autumn, Fv/Fm ratios decreased and concentration...

Research paper thumbnail of Masting in Fagus crenata and its influence on the nitrogen content and dry mass of winter buds

Tree Physiology, 2008

In Fagus, full-mast seeding years are invariably followed by at least one non-mast year. Both flo... more In Fagus, full-mast seeding years are invariably followed by at least one non-mast year. Both flower and leaf primordia develop during the summer within the same winter buds. Flower bud initiation occurs when the N content of developing seeds is increasing rapidly. We hypothesized that competition for nitrogen (N) between developing seeds and buds limits flower primordium formation in mast years and, hence, limits seed production in years following mast years. We tested this hypothesis in three Fagus crenata Blume forests at elevations of 550, 900 and 1500 m. Bud N concentration (N con ), amount of N per bud (N bud ) and dry mass per bud (DM) were compared between a mast year (2005) and the following non-mast year (2006), and between winter buds containing both leaf and flower primoridia (B F ), which were formed during the non-mast year, and winter buds containing leaf primordia only (B L ), which were formed in both mast and non-mast years. In addition, leaf numbers per shoot corresponding to the analyzed buds were counted, and the effect of masting on litter production was analyzed by quantifying the amounts of litter that fell in the years 2004 to 2007. The dry mass and N content of B F formed in 2006 by trees at both 550 and 1500 m were 2.1-3.4-fold higher than the corresponding amounts in B L , although the numbers of leaves per current-year shoot in 2007 that developed from the two bud types in the same individuals did not differ significantly. These results indicate that more N and carbohydrate are expended in producing B F than in producing B L . The amount of litter from reproductive organs produced in the mast year was similar to the amount of leaf litter at 900 and 1500 m, but three times as much at 550 m. Leaf numbers per shoot were significantly lower at all elevations in the mast year than in the non-mast years (and the amount of leaf litter at 550 and 1500 m tended to be lower in the mast year than in the non-mast years. In conclusion, preferential allocation of resources to seeds in the mast year reduced the availability of resources for flower primordium formation, and this may have accounted for the poor seed production in the following non-mast year.

Research paper thumbnail of Stomatal closure induced by high vapor pressure deficit limited midday photosynthesis at the canopy top of Fagus crenata Blume on Naeba mountain in Japan

Trees, 2004

Diurnal changes in gas exchange, chlorophyll fluorescence and leaf water potential (ψ leaf ) were... more Diurnal changes in gas exchange, chlorophyll fluorescence and leaf water potential (ψ leaf ) were measured to determine the environmental and physiological factors that limit carbon gain in the horizontal leaves of Fagus crenata Blume at the canopy top. Although midday depression of the net CO 2 assimilation rate (A n ) and stomatal conductance (gH 2 O) were clearly evident on a fine day, the potential quantum yield of PS II (F v /F m ) was fairly constant around 0.83 throughout the day. This result indicates that the leaves at the canopy top do not suffer from chronic photoinhibition, and the excess energy is dissipated safely. Large reversible increases in non-photochemical quenching (NPQ) were evident on fine days. Therefore, the non-radiative energy dissipation of excess light energy contributed to avoid chronic photoinhibition. The electron transfer rate (ETR) reached maximum during the midday depression, and thus there was no positive relation between ETR and A n under high light conditions, indicating a high rate of photorespiration and the absence of non-stomatal effect during midday. The protective mechanisms such as non-radiative energy dissipation and photorespiration play an important role in preventing photoinhibitory damage, and stomatal limitation is the main factor of midday depression of A n . To separate the effect of air to leaf vapor pressure deficit (ALVPD) and leaf temperature (T leaf ) on gas exchange, the dependencies of A n and gH 2 O on ALVPD and T leaf were measured using detached branches under controlled conditions. A n and gH 2 O were insensitive to an increase in T leaf . With the increase in ALVPD, A n and gH 2 O exhibited more than a 50% decrease even though water supply was optimum, suggesting the dominant role of high ALVPD in the midday depression of gH 2 O. We conclude that midday depression of A n results from the midday stomatal closure caused by high ALVPD.

Research paper thumbnail of Within-branch heterogeneity of the light environment and leaf temperature in a Fagus crenata crown and its significance for photosynthesis calculations

Trees, 2009

... Within-branch heterogeneity of the light environment and leaf temperature in a Fagus crenata ... more ... Within-branch heterogeneity of the light environment and leaf temperature in a Fagus crenata crown and its significance for photosynthesis calculations Atsuhiro Iio Ę Hisakazu Fukasawa Ę Yachiho Nose Ę Masaaki Naramoto Ę Hiromi Mizunaga Ę Yoshitaka Kakubari ...

Research paper thumbnail of Seasonal changes in photosynthesis and nitrogen allocation in leaves of different ages in evergreen understory shrub Daphniphyllum humile

Research paper thumbnail of Interannual variation in leaf photosynthetic capacity during summer in relation to nitrogen, leaf mass per area and climate within a Fagus crenata crown on Naeba Mountain, Japan

Tree Physiology, 2008

During the summers (July and August) of 2002-2005, we measured interannual variation in maximum c... more During the summers (July and August) of 2002-2005, we measured interannual variation in maximum carboxylation rate (V cmax ) within a Fagus crenata Blume crown in relation to climate variables such as air temperature, daytime vapor pressure deficit (VPD) and daily photosynthetic photon flux, leaf nitrogen per unit area (N a ) and leaf mass per unit area (LMA). Climatic conditions in the summers of 2002-2004 differed markedly, with warm and dry atmospheric conditions in 2002, cool, humid and cloudy conditions in 2003, and warm clear conditions in 2004. Conditions in summer 2005 were intermediate between those of summers 2002 and 2003, and similar to recent (8-year) means. In July, marked interannual variation in V cmax was mainly observed in leaves in the high-light environment (relative photon flux > 50%) within the crown. At the crown top, V cmax was about twofold higher in 2002 than in 2003, and V cmax values in 2004 and 2005 were intermediate between those in 2002 and 2003. In August, although interannual variation in V cmax among the years 2003, 2004 and 2005 was less, marked variation between 2002 and the other study years was evident. Multiple regression analysis of V cmax against the climate variables revealed that VPD of the previous 10-30 days had a significant influence on variability in V cmax .

Research paper thumbnail of Seasonal changes in the xanthophyll cycle and antioxidants in sun-exposed and shaded parts of the crown of Cryptomeria japonica in relation to rhodoxanthin accumulation during cold acclimation

Tree Physiology, 2004

Xanthophyll rhodoxanthin, which is present in sun-exposed needles of certain gymnosperms in winte... more Xanthophyll rhodoxanthin, which is present in sun-exposed needles of certain gymnosperms in winter, may have a photoprotective role during long-term cold acclimation. To examine how cold acclimation processes vary within tree crowns and to examine putative correlations between xanthophyll cycle pigments (VAZ), rhodoxanthin and the water-water cycle in photoprotection, we monitored seasonal changes in the activities of two key antioxidant enzymes (ascorbate peroxidase (APX) and glutathione reductase (GR)), pigment composition and chlorophyll fluorescence parameters in sun and shade needles of crowns of the gymnosperm Cryptomeria japonica D. Don. Although APX and GR activities in both sun and shade needles were higher in winter than in summer when assayed at 20°C, differences between seasons were less pronounced when enzymatic activities in summer and winter were assayed at 20 and 5°C, respectively. These results suggest that increases in the potential activity of antioxidant enzymes in winter is an adaptation that helps counterbalance reductions in absolute enzyme activity caused by low temperature, and thus allows the photoprotective capacity of the water-water cycle in C. japonica to be maintained at a roughly constant value throughout the year. In shade needles, the concentration of VAZ increased in winter, but no rhodoxanthin accumulated. Photosynthetic activity was maintained in winter. In sun needles, however, the electron transport rate (ETR) and photochemical quenching (q P ) decreased to their lowest values in December, just before the accumulation of rhodoxanthin, which coincided with the highest amount of VAZ. Changes in rhodoxanthin concentration mirrored changes in VAZ concentration from January to March. Winter values of ETR and q P were comparable with summer values after accumulation of rhodoxanthin, indicating that rhodoxanthin may play a more important role than the VAZ cycle in protecting the photosynthetic apparatus from photodamage in winter. Photosynthetic activity may be modulated, as a result of the interception of light by rhodoxanthin, to match the extent to which absorbed light energy can be utilized in winter when the VAZ cycle is unable to operate effectively because of low temperatures.

Research paper thumbnail of Photosynthetic induction responses to variable light under field conditions in three species grown in the gap and understory of a Fagus crenata forest

Tree Physiology, 1999

Photosynthetic induction responses to abrupt increases in photon flux density (PFD) to 800 and 15... more Photosynthetic induction responses to abrupt increases in photon flux density (PFD) to 800 and 1500 µmol m −2 s −1 from either darkness or 100 µmol m −2 s −1 were examined in situ in leaves of Fagus crenata Blume, Daphniphyllum humile Maxim., and Acer rufinerve Siebold & Zucc. growing in a gap and the understory of an F. crenata forest. Among the species studied, F. crenata exhibited the highest assimilation rate (A 100 ), stomatal conductance (g s100 ) at the background PFD of 100 µmol m −2 s −1 , and A 100 /A max (A max = maximum assimilation rate), in both the gap and the understory. Time required for full induction depended on both background PFD and maximum PFD. The induction period was 2--4-fold shorter at a background PFD of 100 µmol m −2 s −1 than in darkness. For the three understory species, time required to full induction was 2--3-fold longer when irradiance was increased from darkness to 800 µmol m −2 s −1 than when irradiance was increased from darkness to 1500 µmol m −2 s −1 . Acer rufinerve showed higher initial stomatal conductance (g s0 ) and a shorter induction period in the understory than in the gap. Fagus crenata exhibited a similar g s0 and induction period in both habitats. Daphniphyllum humile demonstrated lower g s0 and a longer induction period in the understory than in the gap. These findings indicate that initial stomatal conductance is closely correlated with the photosynthetic induction response. We conclude that the photosynthetic induction response is affected by the light conditions experienced by plants before the sudden increase in irradiance and by the extent of the increase in irradiance.

Research paper thumbnail of Photosynthetic Responses to Lightflecks of Fagus crenata Seedlings Grown in a Gap and Understory of a Deciduous Forest

Journal of Forest Research, Nov 16, 2002

Research paper thumbnail of Significance of afforestation of desert and its evaluation as a countermeasure against carbon dioxide problem

Energy Conversion and Management, Sep 30, 1995

The surface plant is thought to be one of the most feasible final sinks.

Research paper thumbnail of Temperature Control of SMA Artificial Sphincter Utilizing Thermosensitive Magnetic Ferrite Transformer

Journal of the Magnetics Society of Japan, 2003

Research paper thumbnail of ROLES OF PROLINE IN OSMOTIC STRESS TOLERANCE AND MORPHOGENESIS OF Arabidopsis

Plant and Cell Physiology, May 1, 1998

Research paper thumbnail of Soil organic carbon stock is closely related to aboveground vegetation properties in cold-temperate mountainous forests

Geoderma, Jan 15, 2010

The soils of cold-temperate mountainous forest ecosystems contain large carbon pools that may res... more The soils of cold-temperate mountainous forest ecosystems contain large carbon pools that may respond quickly to changes in climate and land use. A better understanding of the temporal-spatial distribution of soil organic carbon (SOC) stock is the first step toward quantifying its potential responses to global changes in climate or land use. The primary objective of this study was to understand the spatial distribution of SOC within a representative mountainous landscape in the cold-temperate zone in Japan. The two dominant tree species in this region are beech (Fagus crenata, a climax species in this zone), and birch (Betula ermanii). In 15 permanent plots located along an altitudinal gradient on the Mount Naeba and Mount Yakio, relationships were determined between SOC and climate (as represented by mean annual temperature), topography (aspect, slope, and altitude), aboveground vegetation properties (stand age, leaf area index, aboveground biomass, mean tree height, tree diameter, stand density, tree basal area, litter depth, and site index), and soil properties (soil bulk density, soil hardness, soil water content, soil root content). Our results indicated that SOC stocks in Japanese cold-temperate forest ecosystems are relatively high, ranging from 12 to 20 kg m − 2 in the top 30 cm of soils. Correlation analysis that included data from all 15 plots (and therefore data from both beech and birch forest and both mountains) suggested that the aboveground vegetation properties, such as aboveground biomass, mean tree height, and stand density, were strongly correlated with the SOC stock. In contrast, topographic factors (aspect and slope) explained SOC spatial distribution for the plots within the same mountain but not for plots from both mountains. Regression models based only on aboveground vegetation properties explained 76.7% of the variability in SOC stocks in beech ecosystems (represented by 10 plots) and 74.9% of the variability in all 15 plots. The strong correlation between aboveground vegetation properties and SOC suggests that measurement of vegetation properties by remote sensing could represent a feasible and rapid method for estimating SOC distribution in a rugged terrain.

Research paper thumbnail of The influence of previous irradiance on photosynthetic induction in three species grown in the gap and understory of a Fagus crenata forest

Photosynthetica, 2001

ABSTRACT

Research paper thumbnail of Spatial and Seasonal Variations in Photosynthetic Properties within a Beech (Fagus crenata Blume) Crown

Journal of Forest Research, Feb 16, 1999

Research paper thumbnail of Temperature Control of SMA Artificial Sphincter Utilizing Thermosensitive Magnetic Ferrite Transformer

Journal of The Magnetics Society of Japan, 2003

Research paper thumbnail of Masting affected intra- and inter-annual variations in stored nitrogen reserves in _Fagus crenata_ trees

Background / Purpose: We tested nitrogen depletion hypothesis in mature Fagus crenata trees by tr... more Background / Purpose: We tested nitrogen depletion hypothesis in mature Fagus crenata trees by tracing seasonal and inter-annual variation in branches, stems and roots for five years, which included three masting events. Main conclusion: Branches served as the main organ for mobile nitrogen storage in Fagus crenata. Although the individual nitrogen storage had both seasonal and interannual variations, it is unlikely that nitrogen storage threshold is the trigger of mast seeding as assumed in the resource budget model.

Research paper thumbnail of Examination of Phase Excitation in a Desktop CLPS

Journal of the Magnetics Society of Japan, 2009

Research paper thumbnail of Diurnal and Seasonal Courses of Photosynthesis, Transpiration and Water Use Efficiency of Apple and Black Locust Seedlings in Different Soil Water Conditios

Journal of the Japanese Society of Revegetation Technology, 1995

Research paper thumbnail of Vertical, horizontal and azimuthal variations in leaf photosynthetic characteristics within a Fagus crenata crown in relation to light acclimation

Tree physiology, 2005

An understanding of spatial variations in gas exchange parameters in relation to the light enviro... more An understanding of spatial variations in gas exchange parameters in relation to the light environment is crucial for modeling canopy photosynthesis. We measured vertical, horizontal and azimuthal (north and south) variations in photosynthetic capacity (i.e., the maximum rate of carboxylation: Vcmax), nitrogen content (N), leaf mass per area (LMA) and chlorophyll content (Chl) in relation to relative photosynthetic photon flux (rPPF) within a Fagus crenata Blume crown. The horizontal gradient of rPPF was similar in magnitude to the vertical gradient of rPPF from the upper to the lower crown. The rPPF in the north quadrant of the crown was slightly lower than in the south quadrant. Nitrogen content per area (Narea), LMA and Vcmax were strictly proportional to rPPF, irrespective of the vertical direction, horizontal direction and crown azimuth, whereas nitrogen content per dry mass, Chl per area and photosynthetic capacity per dry mass (Vm) were fairly constant. Statistical analyses s...

Research paper thumbnail of Photosynthetic acclimation to dynamic changes in environmental conditions associated with deciduous overstory phenology in Daphniphyllum humile, an evergreen understory shrub

Tree physiology, 2005

Photoprotective responses during photosynthetic acclimation in Daphniphyllum humile Maxim, an eve... more Photoprotective responses during photosynthetic acclimation in Daphniphyllum humile Maxim, an evergreen understory shrub that grows in temperate deciduous forests, were examined in relation to changes in light availability and temperature caused by the seasonal dynamics of canopy leaf phenology. Gradual increases in irradiance in the understory from summer to autumn as overstory foliage senesced were accompanied by increased concentrations of xanthophyll cycle pigments (VAZ) in understory leaves. The chlorophyll (Chl) a/b ratio in understory leaves also increased from summer to autumn, reflecting the change in ratio of the light-harvesting antenna to the reaction center. However, low temperatures following overstory leaf fall reduced Rubisco activity. In contrast, the photosynthetic capactiy of leaves of D. humile growing at the forest border, which was higher in summer than that of leaves of understory plants, decreased in autumn. In autumn, Fv/Fm ratios decreased and concentration...

Research paper thumbnail of Masting in Fagus crenata and its influence on the nitrogen content and dry mass of winter buds

Tree Physiology, 2008

In Fagus, full-mast seeding years are invariably followed by at least one non-mast year. Both flo... more In Fagus, full-mast seeding years are invariably followed by at least one non-mast year. Both flower and leaf primordia develop during the summer within the same winter buds. Flower bud initiation occurs when the N content of developing seeds is increasing rapidly. We hypothesized that competition for nitrogen (N) between developing seeds and buds limits flower primordium formation in mast years and, hence, limits seed production in years following mast years. We tested this hypothesis in three Fagus crenata Blume forests at elevations of 550, 900 and 1500 m. Bud N concentration (N con ), amount of N per bud (N bud ) and dry mass per bud (DM) were compared between a mast year (2005) and the following non-mast year (2006), and between winter buds containing both leaf and flower primoridia (B F ), which were formed during the non-mast year, and winter buds containing leaf primordia only (B L ), which were formed in both mast and non-mast years. In addition, leaf numbers per shoot corresponding to the analyzed buds were counted, and the effect of masting on litter production was analyzed by quantifying the amounts of litter that fell in the years 2004 to 2007. The dry mass and N content of B F formed in 2006 by trees at both 550 and 1500 m were 2.1-3.4-fold higher than the corresponding amounts in B L , although the numbers of leaves per current-year shoot in 2007 that developed from the two bud types in the same individuals did not differ significantly. These results indicate that more N and carbohydrate are expended in producing B F than in producing B L . The amount of litter from reproductive organs produced in the mast year was similar to the amount of leaf litter at 900 and 1500 m, but three times as much at 550 m. Leaf numbers per shoot were significantly lower at all elevations in the mast year than in the non-mast years (and the amount of leaf litter at 550 and 1500 m tended to be lower in the mast year than in the non-mast years. In conclusion, preferential allocation of resources to seeds in the mast year reduced the availability of resources for flower primordium formation, and this may have accounted for the poor seed production in the following non-mast year.

Research paper thumbnail of Stomatal closure induced by high vapor pressure deficit limited midday photosynthesis at the canopy top of Fagus crenata Blume on Naeba mountain in Japan

Trees, 2004

Diurnal changes in gas exchange, chlorophyll fluorescence and leaf water potential (ψ leaf ) were... more Diurnal changes in gas exchange, chlorophyll fluorescence and leaf water potential (ψ leaf ) were measured to determine the environmental and physiological factors that limit carbon gain in the horizontal leaves of Fagus crenata Blume at the canopy top. Although midday depression of the net CO 2 assimilation rate (A n ) and stomatal conductance (gH 2 O) were clearly evident on a fine day, the potential quantum yield of PS II (F v /F m ) was fairly constant around 0.83 throughout the day. This result indicates that the leaves at the canopy top do not suffer from chronic photoinhibition, and the excess energy is dissipated safely. Large reversible increases in non-photochemical quenching (NPQ) were evident on fine days. Therefore, the non-radiative energy dissipation of excess light energy contributed to avoid chronic photoinhibition. The electron transfer rate (ETR) reached maximum during the midday depression, and thus there was no positive relation between ETR and A n under high light conditions, indicating a high rate of photorespiration and the absence of non-stomatal effect during midday. The protective mechanisms such as non-radiative energy dissipation and photorespiration play an important role in preventing photoinhibitory damage, and stomatal limitation is the main factor of midday depression of A n . To separate the effect of air to leaf vapor pressure deficit (ALVPD) and leaf temperature (T leaf ) on gas exchange, the dependencies of A n and gH 2 O on ALVPD and T leaf were measured using detached branches under controlled conditions. A n and gH 2 O were insensitive to an increase in T leaf . With the increase in ALVPD, A n and gH 2 O exhibited more than a 50% decrease even though water supply was optimum, suggesting the dominant role of high ALVPD in the midday depression of gH 2 O. We conclude that midday depression of A n results from the midday stomatal closure caused by high ALVPD.

Research paper thumbnail of Within-branch heterogeneity of the light environment and leaf temperature in a Fagus crenata crown and its significance for photosynthesis calculations

Trees, 2009

... Within-branch heterogeneity of the light environment and leaf temperature in a Fagus crenata ... more ... Within-branch heterogeneity of the light environment and leaf temperature in a Fagus crenata crown and its significance for photosynthesis calculations Atsuhiro Iio Ę Hisakazu Fukasawa Ę Yachiho Nose Ę Masaaki Naramoto Ę Hiromi Mizunaga Ę Yoshitaka Kakubari ...

Research paper thumbnail of Seasonal changes in photosynthesis and nitrogen allocation in leaves of different ages in evergreen understory shrub Daphniphyllum humile

Research paper thumbnail of Interannual variation in leaf photosynthetic capacity during summer in relation to nitrogen, leaf mass per area and climate within a Fagus crenata crown on Naeba Mountain, Japan

Tree Physiology, 2008

During the summers (July and August) of 2002-2005, we measured interannual variation in maximum c... more During the summers (July and August) of 2002-2005, we measured interannual variation in maximum carboxylation rate (V cmax ) within a Fagus crenata Blume crown in relation to climate variables such as air temperature, daytime vapor pressure deficit (VPD) and daily photosynthetic photon flux, leaf nitrogen per unit area (N a ) and leaf mass per unit area (LMA). Climatic conditions in the summers of 2002-2004 differed markedly, with warm and dry atmospheric conditions in 2002, cool, humid and cloudy conditions in 2003, and warm clear conditions in 2004. Conditions in summer 2005 were intermediate between those of summers 2002 and 2003, and similar to recent (8-year) means. In July, marked interannual variation in V cmax was mainly observed in leaves in the high-light environment (relative photon flux > 50%) within the crown. At the crown top, V cmax was about twofold higher in 2002 than in 2003, and V cmax values in 2004 and 2005 were intermediate between those in 2002 and 2003. In August, although interannual variation in V cmax among the years 2003, 2004 and 2005 was less, marked variation between 2002 and the other study years was evident. Multiple regression analysis of V cmax against the climate variables revealed that VPD of the previous 10-30 days had a significant influence on variability in V cmax .

Research paper thumbnail of Seasonal changes in the xanthophyll cycle and antioxidants in sun-exposed and shaded parts of the crown of Cryptomeria japonica in relation to rhodoxanthin accumulation during cold acclimation

Tree Physiology, 2004

Xanthophyll rhodoxanthin, which is present in sun-exposed needles of certain gymnosperms in winte... more Xanthophyll rhodoxanthin, which is present in sun-exposed needles of certain gymnosperms in winter, may have a photoprotective role during long-term cold acclimation. To examine how cold acclimation processes vary within tree crowns and to examine putative correlations between xanthophyll cycle pigments (VAZ), rhodoxanthin and the water-water cycle in photoprotection, we monitored seasonal changes in the activities of two key antioxidant enzymes (ascorbate peroxidase (APX) and glutathione reductase (GR)), pigment composition and chlorophyll fluorescence parameters in sun and shade needles of crowns of the gymnosperm Cryptomeria japonica D. Don. Although APX and GR activities in both sun and shade needles were higher in winter than in summer when assayed at 20°C, differences between seasons were less pronounced when enzymatic activities in summer and winter were assayed at 20 and 5°C, respectively. These results suggest that increases in the potential activity of antioxidant enzymes in winter is an adaptation that helps counterbalance reductions in absolute enzyme activity caused by low temperature, and thus allows the photoprotective capacity of the water-water cycle in C. japonica to be maintained at a roughly constant value throughout the year. In shade needles, the concentration of VAZ increased in winter, but no rhodoxanthin accumulated. Photosynthetic activity was maintained in winter. In sun needles, however, the electron transport rate (ETR) and photochemical quenching (q P ) decreased to their lowest values in December, just before the accumulation of rhodoxanthin, which coincided with the highest amount of VAZ. Changes in rhodoxanthin concentration mirrored changes in VAZ concentration from January to March. Winter values of ETR and q P were comparable with summer values after accumulation of rhodoxanthin, indicating that rhodoxanthin may play a more important role than the VAZ cycle in protecting the photosynthetic apparatus from photodamage in winter. Photosynthetic activity may be modulated, as a result of the interception of light by rhodoxanthin, to match the extent to which absorbed light energy can be utilized in winter when the VAZ cycle is unable to operate effectively because of low temperatures.

Research paper thumbnail of Photosynthetic induction responses to variable light under field conditions in three species grown in the gap and understory of a Fagus crenata forest

Tree Physiology, 1999

Photosynthetic induction responses to abrupt increases in photon flux density (PFD) to 800 and 15... more Photosynthetic induction responses to abrupt increases in photon flux density (PFD) to 800 and 1500 µmol m −2 s −1 from either darkness or 100 µmol m −2 s −1 were examined in situ in leaves of Fagus crenata Blume, Daphniphyllum humile Maxim., and Acer rufinerve Siebold & Zucc. growing in a gap and the understory of an F. crenata forest. Among the species studied, F. crenata exhibited the highest assimilation rate (A 100 ), stomatal conductance (g s100 ) at the background PFD of 100 µmol m −2 s −1 , and A 100 /A max (A max = maximum assimilation rate), in both the gap and the understory. Time required for full induction depended on both background PFD and maximum PFD. The induction period was 2--4-fold shorter at a background PFD of 100 µmol m −2 s −1 than in darkness. For the three understory species, time required to full induction was 2--3-fold longer when irradiance was increased from darkness to 800 µmol m −2 s −1 than when irradiance was increased from darkness to 1500 µmol m −2 s −1 . Acer rufinerve showed higher initial stomatal conductance (g s0 ) and a shorter induction period in the understory than in the gap. Fagus crenata exhibited a similar g s0 and induction period in both habitats. Daphniphyllum humile demonstrated lower g s0 and a longer induction period in the understory than in the gap. These findings indicate that initial stomatal conductance is closely correlated with the photosynthetic induction response. We conclude that the photosynthetic induction response is affected by the light conditions experienced by plants before the sudden increase in irradiance and by the extent of the increase in irradiance.