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Volume 61, Issue 2
June
Displaying 1-4 of 4 articles from this issue
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Honghyun KIM, Takashi HIRANO, Shin-ichi URANO2005 Volume 61 Issue 2 Pages 95-104
Published: 2005
Released on J-STAGE: December 20, 2006
JOURNAL FREE ACCESSWe collected leaf litter from a deciduous broadleaf forest and a larch forest in Hokkaido, Japan naturally without using litter traps or litter bags. The litter collection was conducted every month from October 2001 through October 2002 except in the snowy season. We measured the CO2 production rate of the litter samples through microbial respiration using the chamber method in a laboratory under different temperature and moisture conditions to investigate the seasonal pattern and temperature and moisture responses of CO2 production at the early stage of litter decomposition. Seasonal variation was found in the CO2 production rate per unit of litter dry weight (Pdw), or the litter decomposition rate, for both broadleaf and larch litters. Although seasonal patterns differed somewhat according to temperatures and species, Pdw reached the minimum in June. The moisture sensitivity of Pdw decreased with time and reached the minimum in summer for both broadleaf and larch litters, whereas the seasonal pattern of the temperature sensitivity (Q10) was not clear. The seasonal pattern of Pdw was explained by its C:N ratio for broadleaf litter. For larch litter, however, the relationship between Pdw and the C:N ratio was complicated because of fresh litterfall supplied gradually before defoliation. The temperature and moisture sensitivities of Pdw changed in parallel with the C:N ratio for both broadleaf and larch litters, respectively. These facts suggest the importance of litter chemical quality in the early decomposition process of fresh litter and the validity of the C:N ratio as an index of litter quality.View full abstractDownload PDF (803K) -
Wei GU, Ning LI, Feng XIE, Seiji HAYAKAWA2005 Volume 61 Issue 2 Pages 105-111
Published: 2005
Released on J-STAGE: December 20, 2006
JOURNAL FREE ACCESSThe sea ice reserves in Liaodong Bay at periods of winter 1999/2000 was estimated using remote sensing. The ice thickness was estimated based on the exponent relationship between ice thickness and its reflectivity. The ice area was obtained by NOAA/AVHRR data at channel 1. To understand the distribution of sea ice reserves, Liaodong Bay was divided into 11 regions and each region was further subdivided into 5 plots in terms of the topographic trend and the distance from coast. The sea ice at the reserves was statistically counted for each plot over different periods. The maximum ice reserve in a normal ice year during the period of grand ice in a natural environment is 30×108 m3, with the center of maximum ice thickness moving from the center of the sea to the eastern coast with the passing of a specific ice period. More ice reserves are distributed on the eastern coast of Liaodong Bay located in the regions between Ying-Kou and Xiong-Yue, and the western coastal regions around Xing-Cheng, which make up 30%-50% of the total ice reserves within Liaodong Bay. These regions are in the best positions to be set up as exploited bases. With respect to the increasing distance from the coast, the sea ice reserves decreased in the eastern coast, increasing slightly to the western coast.View full abstractDownload PDF (1238K)
Full Papers (in Japanese)
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Akira TANI, Katsuhiro FUSHIMI2005 Volume 61 Issue 2 Pages 113-122
Published: 2005
Released on J-STAGE: December 20, 2006
JOURNAL FREE ACCESSIsoprene is a major compound emitted by plants. Effects of light and temperature on isoprene emission rate (E) of Edgeworthia chrysantha was investigated. A leaf cuvette was modified to collect volatiles emitted by the plant leaf and its photosynthetic rate (A) and E were determined for the same periods. The experimental results showed that E value increased with increases in photosynthetic photon flux (PPF) and leaf temperature up to 40°C. A change in A value against PPF was similar to the change in E, but, for leaf temperature, the A value had a maximum between 25 and 30°C. As a result, carbon ratio of isoprene emission to photosynthetic uptake increased greatly with an increase in leaf temperature and had the highest value of 1-5% at 40°C. A model (G93) was employed to explain the plant isoprene emission responses to PPF and leaf temperature. The model could explain the isoprene emission within the RMS error of 3 nmol m-2 s-1, while emission factor ε calculated for standard conditions of 1000µmol m-2 s-1 PPF and 30°C leaf temperature was largely different between measurements. This suggests that determining representative ε value for a whole plant and stands is essential to estimate a regional scale isoprene emission.View full abstractDownload PDF (981K) -
Toshikazu KAWAKATA2005 Volume 61 Issue 2 Pages 123-129
Published: 2005
Released on J-STAGE: December 20, 2006
JOURNAL FREE ACCESSThe amount of solar radiation absorbed by a crop canopy is correlated with crop production, and thus it is necessary to estimate both transmission and reflection around the canopy for crop growth models. The “forward and backward streams” representation of radiation has been refined to account for both transmission and reflection in the crop canopy. However, this model has not been applied to a rice canopy through the growing period. The purpose of this study is to examine whether the two-stream model is applicable to the rice canopy, and to investigate the parameters of the model. The values for both transmittance below the rice canopy and reflectance above it that were derived from the two-stream model represent the observed values throughout the growing period. The inclination factor of leaves (F), which is used in the two-stream model, was almost equivalent to the extinction coefficient of transmittance in the case of the rice canopy.View full abstractDownload PDF (1044K)
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