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Volume 59, Issue 4
December
Displaying 1-4 of 4 articles from this issue
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Makoto OOBA, Kentaro TAKAGI, Hidenori TAKAHASHIArticle type: Others
Subject area: Others
2003 Volume 59 Issue 4 Pages 259-267
Published: 2003
Released on J-STAGE: December 17, 2004
JOURNAL FREE ACCESSPhotosynthesis o plants has been studied under a condition of alternating irradiance (irradiance changes between high and low values periodically). Based on results of previous studies, we hypothesized as follows: The mean photosynthetic rate (A-) is minimum under conditions of alternating light with a period of about 102 s; when the period is in the order of 1 and 103 s, A- approaches a steady-state photosynthetic rate (A) at mean irradiance and mean A at both irradiances, respectively. We developed an unsteady-state leaf model to verify this hypothesis and estimated the relationship between the period and A-. The hypothesis was verified by using the model. The relationship between the scale of fluctuating light and A- which was shown in this study provides information to estimate dynamic response of a plant in a complicated light environment.View full abstractDownload PDF (610K)
Full Papers(in Japanese)
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Yasuhiro ISHIGAMI, Yo SHIMIZU, Kenji OMASAArticle type: Others
Subject area: Others
2003 Volume 59 Issue 4 Pages 269-276
Published: 2003
Released on J-STAGE: December 17, 2004
JOURNAL FREE ACCESSIn a previous paper, we modified some sub-models of BIOME3 to be applied to 1×1 km mesh data in order to increase the accuracy of simulation.
Using this modified model, we estimated potential natural vegetation distribution under climatic change using 4 types of GCM experiment data. GCM data that can be used presently have rough spatial resolution, so it is difficult to estimate the effect of climatic change at a local scale. Therefore, we used GCM data around Japan that was interpolated to a 10×10 km mesh.
We calculated the NPP, and predicted the distribution of potential natural vegetation and its vulnerability for the 2020s, 2050s and 2080s. Results from the simulation indicated the possibility of 60-100% increase of NPP in the 2080s. The increase in NPP was explained by the increase in air temperature and the concentration of CO2. Potential natural vegetation in Japan would be affected over a wide area by climatic change. In particular, the alpine plants/subalpine conifer forest area would decrease. In mixed forest in the Hokkaido area, where broad-leaved deciduous trees and conifer trees coexist, broad-leaved deciduous trees would become dominant. Broad-leaved evergreen forest area would expand, and the subtropical forest would to a prior species along the coastline of western Japan.View full abstractDownload PDF (2455K) -
Yasuyuki WAKIYAMA, Kimio INOUE, Kou NAKAZONOArticle type: Others
Subject area: Others
2003 Volume 59 Issue 4 Pages 277-286
Published: 2003
Released on J-STAGE: December 17, 2004
JOURNAL FREE ACCESSThe present study was conducted to show a simple model for rice yield predicting by using a vegetation index (NDVI) derived from satellite and meteorological data. In a field experiment, the relationship between the vegetation index and radiation absorbed by the rice canopy was investigated from transplanting to maturity. Their correlation held. This result revealed that the vegetation index could be used as a measure of absorptance of solar radiation by rice canopy. NDVI multiplied by solar radiation (SR) every day was accumulated (Σ(SR·NDVI)) from the field experiment. Σ(SR·NDVI) was plotted against above ground dry matter. It was obvious that they had a strong relationship. Rice yield largely depends on solar radiation and air temperature during the ripening period. Air temperature affects dry matter production. Relationships between Y SR-1 (Y: rice yield, SR: solar radiation) and mean air temperature were investigated from meteorological data and statistical data on rice yield. There was an optimum air temperature, 21.3°C, for ripening. When it was near 21.3°C in the ripening period, the rice yield was higher. We proposed a simple model for yield prediction of rice based on these results. The model is composed with SR·NDVI and the optimum air temperature. Vegetation index was derived from 3 years, LANDSAT TM data in Toyama, Ishikawa, Fukui and Nagano prefectures at heading. The meteorological data was used from AMeDAS data. The model was described as follows:
Y=0.728 SR·NDVI−2.04(T−21.3)2+282 (r2=0.65, n=43)
where Y is rice yield (kg 10a-1), SR is solar radiation (MJ m-2) during the ripening period (from 10 days before heading to 30 days after heading), T is mean air temperature (°C) during the ripening period. RMSE was 33.7kg 10a-1. The model revealed good precision.View full abstractDownload PDF (599K) -
Takahiro HAMASAKI, Masumi OKADAArticle type: Others
Subject area: Others
2003 Volume 59 Issue 4 Pages 287-296
Published: 2003
Released on J-STAGE: December 17, 2004
JOURNAL FREE ACCESSThe effect of row cover on the growth of Komatsuna (Brassica campestris L. rapifera group) was evaluated using a simple model describing the relationship between temperature and leaf growth. The model was developed from a growth chamber experiment and shows that a) relative leaf area growth rate (RLGR) varies inversely as the 0.6th power of leaf area (LA) and b) RLGR is related to temperature by a sigmoid curve. Separate field experiments were carried out over six periods of growth and the parameters of the model were derived so as to fit the model to the results of these experiments. The growth-promoting effect of row cover was best described when the model was driven by soil temperature rather than air temperature, and it was therefore concluded that the growth-promoting effect of row cover strongly depends on its ability to warm the soil. The model-aided analysis of field-grown Komatsuna showed that leaf growth under row cover was stimulated most at lower temperatures and in the earlier growth stages. The effect of temperature was explained by the relationship between soil temperature and RLGR, in which the temperature-stimulation of RLGR decreases at higher temperatures. The effect of early growth stage was due to the enhanced rate of soil warming that results from better penetration of solar radiation to the soil surface when canopy leaf area is relatively undeveloped. Although both of these effects are already known empirically, the model-aided analysis used in the present study is able to explain them quantitatively.View full abstractDownload PDF (5924K)
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