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Volume 63, Issue 4
Displaying 1-4 of 4 articles from this issue
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Full Papers
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Tomoyuki KITAMOTO, Masahito UEYAMA, Yoshinobu HARAZONO, Toru IWATA, Su ...2007 Volume 63 Issue 4 Pages 171-183
Published: 2007
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA simple empirical model was developed to calculate the carbon fluxes on a regional scale by integrating the observed ground truth data at a black spruce forest in interior Alaska in 2005 and original NOAA/AVHRR data. The satellite-derived variables of normalized difference vegetation index (NDVI) and land surface temperature (LST) were related with measured leaf area index (LAI) and measured CO2 flux (NEE) using a sub-empirical model, CBAT. In order to scale up the observed fluxes, gross primary production (GPP) and ecosystem respiration (Reco) were separately determined using NDVI and LST. The parameters and relationships were determined by applying the observed ground truth data in 2005. Comparing to the observed dataset, the diurnal and seasonal variations were calculated reasonably. The model satisfactorily reproduced Reco as an hourly base, but GPP tended to be an overestimation caused by the eliminated effect of vapor pressure deficit (VPD). The GPP, Reco and NEE over Alaska's black spruce forests were estimated as 2330, 1920 and -410 g CO2 m-2, respectively, during the growing season in 2005. Seasonal variations of estimated carbon flux distributions reflected heterogeneous ecosystem conditions.View full abstractDownload PDF (1345K)
Full Papers (in Japanese)
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Mariko FUJISAWA, Kazuhiko KOBAYASHI2007 Volume 63 Issue 4 Pages 185-191
Published: 2007
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSRecent studies show hastening of the onset of the plant growing season and delay in the end of the growing season for the last several decades. With the well-established dependence of plant phenology on temperature, the phenological trends are interpreted as an indication of global warming. However, for several decades, other changes, e.g., those in varieties and agronomic practices, may also have contributed to the phenological trends. In this study, we analyzed the records of temperature and phenological events (budding, flowering and harvest) in the apple (Malus pumila var. domestica) from 1977 to 2004 at two locations (Kuroishi and Fukushima) in northern Japan. To each time series, we fitted a smoothing spline to obtain the long-term trend, and calculated the anomaly of deviations in yearly observations from the long-term trend. We found acceleration of budding by 0.23 d/y (Kuroishi and Fukushima), and that of flowering by 0.24 d/y (Kuroishi) and 0.27 d/y (Fukushima). The timing of budding was closely correlated with mean air temperature in March at a sensitivity of -3.9 d/°C (Kuroishi) and -4.3 d/°C (Fukushima). The temperature sensitivity showed no significant difference between the long-term trends and the anomalies. Flowering results were very close with one exception in Kuroishi: the temperature sensitivity in the long-term trend (-3.4 d/°C) was significantly less than that for the anomaly (-5.2 d/°C). The date of harvest showed no significant temporal trends or correlation with air temperature. These results indicate that the acceleration of budding in the apple can be regarded as a signal of a temperature increase, and that the acceleration of flowering may be a result of the temperature increase despite in an exceptional case.View full abstractDownload PDF (1177K) -
Hirakazu SEKI, Tsunao OKUMURA2007 Volume 63 Issue 4 Pages 193-200
Published: 2007
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn this paper, NO (nitrogen monooxide) adsorption ability of a soil filter was considered both experimentally and theoretically as the first step in developing a new nitrogen recovery system using the soil filter and plants. In this proposed system, a gas component NO that is discharged from fixed sources such as incineration plants will be trapped by a soil filter and transformed into NO3-, and then absorbed by the plants. At first, by comparing the O2 breakthrough curve obtained experimentally with that calculated from the analytical solution of O2 concentration, the apparent gas diffusivity in the soil filter was obtained. Next, assuming that the rate of adsorption follows a linear driving force (LDF) model, two parameters a (equilibrium constant) and Θ (time constant) of the LDF model were evaluated for each experiment, and a solution of NO concentration was numerically derived. The validity of the solution was proved by comparing the NO breakthrough curve obtained experimentally with that calculated numerically. The value of Θ greatly differs according to soil texture, and the value of a is large under moderate moisture content conditions. Since the adsorption ability of the soil filter is small, however, it seems insufficient to use the soil alone as a filter to trap NO from fixed sources.View full abstractDownload PDF (1049K)
Short Papers
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Satoshi KITAOKA, Tadashi SAKATA, Takayoshi KOIKE, Hiroyuki TOBITA, Aki ...2007 Volume 63 Issue 4 Pages 201-206
Published: 2007
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA recent study by Keppler et al. (2006: Nature 439, 187-191) reported methane emission from leaves under aerobic conditions, and suggested that forests are major methane sources. It is therefore important to determine the contribution of temperate forest to worldwide methane gas evolution. We studied methane emission from typical tree species native to northern Japan grown under both ambient and high CO2 concentrations ([CO2]), and accordingly consider methane emission rates on the global scale. We used three tree species: larch (Larix kaempferi (Lamb.) Carrière), birch (Betula maximowicziana Regel) and oak (Quercus mongolica Fisch. Ex Ledeb. var. crispula (Blume) Ohashi). Fresh leaves were incubated at 35°C under illumination, and methane emission was monitored at 24 hr intervals. Methane emission was observed in leaves of all three species; specific patterns were found. Larch produced the most methane. Oak produced least methane at high CO2 concentration. There are currently large variations in estimates of the total methane emission on the global scale. The present results suggest that further accurate methane flux studies are necessary in order to determine total methane emission rates at the global scale.View full abstractDownload PDF (716K)
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