Yoichi Kanazawa
Kobe University
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Featured researches published by Yoichi Kanazawa.
Tree Physiology | 2009
Naoki Makita; Yasuhiro Hirano; Masako Dannoura; Yuji Kominami; Takeo Mizoguchi; Hiroaki Ishii; Yoichi Kanazawa
Fine root respiration is a significant component of carbon cycling in forest ecosystems. Although fine roots differ functionally from coarse roots, these root types have been distinguished based on arbitrary diameter cut-offs (e.g., 2 or 5 mm). Fine root morphology is directly related to physiological function, but few attempts have been made to understand the relationships between morphology and respiration of fine roots. To examine relationships between respiration rates and morphological traits of fine roots (0.15-1.4 mm in diameter) of mature Quercus serrata Murr., we measured respiration of small fine root segments in the field with a portable closed static chamber system. We found a significant power relationship between mean root diameter and respiration rate. Respiration rates of roots<0.4 mm in mean diameter were high and variable, ranging from 3.8 to 11.3 nmol CO2 g(-1) s(-1), compared with those of larger diameter roots (0.4-1.4 mm), which ranged from 1.8 to 3.0 nmol CO2 g(-1) s(-1). Fine root respiration rate was positively correlated with specific root length (SRL) as well as with root nitrogen (N) concentration. For roots<0.4 mm in diameter, SRL had a wider range (11.3-80.4 m g(-1)) and was more strongly correlated with respiration rate than diameter. Our results indicate that a more detailed classification of fine roots<2.0 mm is needed to represent the heterogeneity of root respiration and to evaluate root biomass and root morphological traits.
Tellus B | 2007
Mayuko Jomura; Yuji Kominami; Koji Tamai; Takafumi Miyama; Yoshiaki Goto; Masako Dannoura; Yoichi Kanazawa
We evaluated the carbon budget of coarse woody debris (CWD) in a temperate broad-leaved secondary forest. On the basis of a field survey conducted in 2003, the mass of CWD was estimated at 9.30 tC ha-1, with snags amounting to 60% of the total mass. Mean annual CWD input mass was estimated to be 0.61 tC ha-1 yr-1 by monitoring tree mortality in the forest from 1999 to 2004. We evaluated the CWD decomposition rate as the CO2 evolution rate from CWD by measuring CO2 emissions from 91 CWD samples (RCWD) with a closed dynamic chamber and infrared gas analysis system. The relationships between RCWD and temperature in the chamber, water content of the CWD, and other CWD characteristics were determined. By scaling the measured RCWD to the ecosystem, we estimated that the annual RCWD in the forest in 2003 was 0.50 tC ha-1 yr-1 or 10%–16% of the total heterotrophic respiration. Therefore, 0.11 tC ha-1 yr-1 or 7% of the forest net ecosystem production was sequestered by CWD. In a young forest, in which CWD input and decomposition are not balanced, the CWD carbon budget needs to be quantified for accurate evaluation of the forest carbon cycle and NEP.
Soil Science and Plant Nutrition | 2007
Tomoaki Morishita; Tadashi Sakata; Masamichi Takahashi; Shigehiro Ishizuka; Takeo Mizoguchi; Yoshiyuki Inagaki; Kazuhiko Terazawa; Satoshi Sawata; Masanori Igarashi; Hiroshi Yasuda; Yasuhiro Koyama; Yoshihito Suzuki; Nobuyuki Toyota; Masamichi Muro; Masaru Kinjo; Hirokazu Yamamoto; Daitaro Ashiya; Yoichi Kanazawa; Tetsu Hashimoto; Hidetaka Umata
Abstract To determine the means and variations in CH4 uptake and N2O emission in the dominant soil and vegetation types to enable estimation of annual gases fluxes in the forest land of Japan, we measured monthly fluxes of both gases using a closed-chamber technique at 26 sites throughout Japan over 2 years. No clear seasonal changes in CH4 uptake rates were observed at most sites. N2O emission was mostly low throughout the year, but was higher in summer at most sites. The annual mean rates of CH4 uptake and N2O emission (all sites combined) were 66 (2.9–175) µg CH4-C m−2 h−1 and 1.88 (0.17–12.5) µg N2O-N m−2 h−1, respectively. Annual changes in these fluxes over the 2 years were small. Significant differences in CH4 uptake were found among soil types (P < 0.05). The mean CH4 uptake rates (µg CH4-C m−2 h−1) were as follows: Black soil (95 ± 39, mean ± standard deviation [SD]) > Brown forest soil (60 ± 27) ≥ other soils (20 ± 24). N2O emission rates differed significantly among vegetation types (P < 0.05). The mean N2O emission rates (µg N2O-N m−2 h−1) were as follows: Japanese cedar (4.0 ± 2.3) ≥ Japanese cypress (2.6 ± 3.4) > hardwoods (0.8 ± 2.2) = other conifers (0.7 ± 1.4). The CH4 uptake rates in Japanese temperate forests were relatively higher than those in Europe and the USA (11–43 µg CH4-C m−2 h−1), and the N2O emission rates in Japan were lower than those reported for temperate forests (0.23–252 µg N2O-N m−2 h−1). Using land area data of vegetation cover and soil distribution, the amount of annual CH4 uptake and N2O emission in the Japanese forest land was estimated to be 124 Gg CH4-C year−1 with 39% uncertainty and 3.3 Gg N2O-N year−1 with 76% uncertainty, respectively.
Plant Biosystems | 2008
Masako Dannoura; Yasuhiro Hirano; Tetsuro Igarashi; Masahiro Ishii; Kenji Aono; Keitaro Yamase; Yoichi Kanazawa
Abstract Coarse tree roots, which are responsible for most root carbon storage, are usually measured by destructive methods such as excavation and coring. Ground penetrating radar (GPR) is a non-destructive tool that could be used to detect coarse roots in forest soils. In this study, we examined whether the roots of Cryptomeria japonica, a major plantation species in Japan, can be detected with GPR. We also looked for factors that impact the analysis and detection of roots. Roots and wooden dowels of C. japonica were buried 30 cm deep in sandy granite soil. From GPR measurements with a 900 MHz antenna, the distribution and diameter of samples in several transects were recorded. The buried roots were detected clearly and could be distinguished at diameters of 1.1–5.2 cm. There were significant positive relationships between root diameter and parameters extracted from the resultant GPR waveform. The difference in water content between roots and soil is a crucial factor impacting the ability to detect roots with GPR. We conclude that GPR can be used as a non-destructive tool, but further investigation is needed to determine optimal conditions (e.g. water content) and analytical methods for using GPR to examine roots in forest sites.
Tellus B | 2006
Masako Dannoura; Yuji Kominami; Koji Tamai; Mayuko Jomura; Takafumi Miyama; Yoshiaki Goto; Yoichi Kanazawa
To separate CO2 efflux from roots (Rr) and soil (Rs), we developed a system to measure Rr continuously. Using this system, seasonal variation in Rr was obtained in a temperate forest in Japan. We measured Rs, CO2 efflux from mineral soil (Rm) and environmental factors simultaneously, and the characteristic and seasonality of Rr were analysed in comparison with Rs. Rr and Rs showed different responses to soil water content: Rs decreased with decreasing soil water content, whereas Rr peaked at relatively low soil water content. Rr/Rs decreased from 64.8% to 27.3% as soil water content increased from 0.075 to 0.225 cm cm-3. The relationship between respiration and temperature appears to change seasonally in response to phenological and biological factors. Rr showed clear seasonal variation as a function of soil temperature. During the growing period, Rr exhibited a higher rate at the same soil temperature than during other periods, which may be due to phenological influences such as fine root dynamics. Rs decreased during the summer despite high soil temperatures. The seasonal peak for Rs occurred earlier than that for soil temperature. Rr/Rs ranged between 25% and 60% over the course of the year.
Journal of Forest Research | 2003
Tatsuhiko Nobuhiro; Koji Tamai; Yuji Kominami; Takafumi Miyama; Yoshiaki Goto; Yoichi Kanazawa
A new system was developed for measuring soil CO2 efflux. The chamber in this system contains a small infrared CO2 gas analyzer. This system does not need air tubes or pumps for circulating air, so it is expected to offer the advantages of mobility and durability. This system was verified by a comparison with measurements made by using a closed-dynamic-chamber (CDC) system. The spatial variation in the soil CO2 efflux in a broadleaved deciduous forest was measured using the new system. The soil CO2 efflux at sampling locations 50–70 cm apart varied within a range of 60%–150%. This variation was smaller than the variation due to differences in soil characteristic reflected in different moisture conditions, etc.
Forest Ecology and Management | 1991
Akira Osawa; Moriyoshi Ishizuka; Yoichi Kanazawa
Abstract We present a profile theory of tree growth that describes the relationship between stem growth of an entire tree and stem mass density at crown base. Several other variables, e.g. height growth, total foliage mass, and length of clear bole, are included in the equation. The theory also predicts leaf efficiency from those variables. This is an improved version of another idea that proposed that the stem mass density at crown base is equivalent to the stem growth of an entire tree. The previous argument was based on a new interpretation of the profile diagram for production structure of plant populations and individuals. The profile theory is built on three assumptions: (1) vertical distribution pattern of foliage mass does not change, except that it moves upward over time; (2) stem-wood increment at a certain location along a stem is proportional to the foliage mass above that point (the proportionality constant being μ); and (3) annual height growth is constant. The present theory and the previous one were tested comparatively using the production data from individual trees of six species: Cryptomeria japonica, Chamaecyparis obtusa, Quercus mongolica, Betula platyphylla, Abies sachalinensis and Larix kaempferi. Judging from the linear regression analysis of calculated versus observed value relationships, including examination of such statistics as the mean square error (MSE) and the coefficient of determination (R2), the profile theory yielded improved predictions of the stem growth and leaf efficiency in all cases but one; stem growth of B. platyphylla was the exception. The original theory failed to produce reasonable predictions especially in A. sachalinensis and L. kaempferi. The theory was then generalized by relaxing the second and the third assumptions. It was assumed that the proportionality constant, μ, and the height growth had shifted to new values during the most recent years. This was to account for the sudden reduction in radial increment that was noted in some samples of B. platyphylla and A. sachalinensis. The fit of the model to the data from these two species was greatly improved by the more generalized theory. Overall, predictions from the profile theory (including its generalized form) were not different from the observed values at the 5% significance level. The calculated values of stem growth and leaf efficiency agreed with the observation reasonably well.
Trees-structure and Function | 2005
Akira Osawa; Nahoko Kurachi; Yojiro Matsuura; Mayuko Jomura; Yoichi Kanazawa; Masaru Sanada
Accuracy of a stand reconstruction technique was examined by comparing the estimated values of the aboveground biomass, total stem volume, stem volume growth, and stand density of Abies sachalinensis stands to those observed between 1980 and 1998 in Hokkaido, northern Japan. Census data from two stands established in 1973, one fertilized and the other unfertilized, were used for the examination. The stand statistics in the past were estimated from the DBH and height of individual trees measured in 1998, data on the aboveground biomass and stem volume with bark for nine living trees of various sizes harvested in each plot in 1998 or in 1999, and data from the stem analysis of the same harvested trees. We showed that the reconstructed patterns of the frequency distribution in aboveground biomass and in stem volume were generally the same as those observed in both plots and in any year in the past (except for 1982 and/or 1980), and that the reproduced patterns of stand development over time were similar to those observed directly in the past. Accuracy in predicting stand statistics was generally in the order of ±10% relative error. We consider that the present method of stand reconstruction could be used to estimate aboveground biomass, total stem volume, and stem volume growth of a stand in the past. Interpretation of results for the early years (1982 and 1980) and for the stand density requires caution.
Plant and Soil | 2009
Yasuhiro Hirano; Masako Dannoura; Kenji Aono; Tetsurou Igarashi; Masahiro Ishii; Keitarou Yamase; Naoki Makita; Yoichi Kanazawa
Agricultural and Forest Meteorology | 2008
Yuji Kominami; Mayuko Jomura; Masako Dannoura; Yoshiaki Goto; Koji Tamai; Takafumi Miyama; Yoichi Kanazawa; Shinji Kaneko; Motonori Okumura; Noriko Misawa; Shogo Hamada; Taizo Sasaki; Hitoshi Kimura; Yoshikazu Ohtani