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Volume 60, Issue 4
December
Displaying 1-8 of 8 articles from this issue
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Invited Review Papers
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David M. OLSZYK, Connie A. BURDICK, Thomas G. PFLEEGER, E. Henry LEE, ...2004 Volume 60 Issue 4 Pages 221-242
Published: 2004
Released on J-STAGE: May 09, 2006
JOURNAL FREE ACCESSUse of chemical herbicides to reduce weed competition is a major contributing factor to the high productivity of conventional intensive agricultural cropping systems. However, because of their inherent phytotoxicity, movement of herbicides from target crops and soils can adversely affect non-target terrestrial plants. We review current trends in herbicide usage, evidence for effects of herbicides on non-target plants, and risk assessment methodology used to determine potential non-target effects of herbicides. Persistent questions regarding whether or not standard plant tests and analysis protocols provide adequate information for risk assessments, lead us to suggest research needed to improve the risk assessment methodology for effects of potential herbicide drift on non-target plants. This research includes spatial analysis to identify non-target plant species at risk, and development of new biochemical/molecular, phytotoxicological, and ecologically based tests.View full abstractDownload PDF (913K)
Full Papers
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Taichi MAKI, Yosuke HIRAYAMA, Akira TAKEMASA, Miho OBU2004 Volume 60 Issue 4 Pages 243-251
Published: 2004
Released on J-STAGE: May 09, 2006
JOURNAL FREE ACCESSThe reclaimed land in Isahaya Bay is approximately 816 ha in area, including the central area (706 ha) and the Oe area (110 ha). The reclamation will be complete in 2007. It will be necessary to perform continued meteorological research on the lands, which are intended for agricultural usage after the completion of reclamation. These lands are not protected against the wind, and strong winds do frequently blow across this wide and horizontal area. In order to use this area as arable land, it will be necessary to introduce many windbreaks for the protection of these open fields. A windbreak net of 2.4 m height with an open space of 0.4 m between the bottom of the net and the ground was constructed on the open field and its length was 100 m. The windbreak net was made of blue polyethylene Russell net with 6 mm mesh. The wind speed was measured from a distance of -20H windward to 25H leeward and at heights of 6, 3, 2, 1 and 0.5 m, where H represents the height of the net on the ground, and the numerals the multiple distances from the net, and negative signs denote the windward side and positive signs the leeward. Wind speed, air temperature, relative humidity, and surface soil and leaf temperatures were measured from Nov. 2003 to Feb. 2004. Variations of horizontal, vertical and isopleths of the wind speed under conditions of both weak and strong winds were obtained. Wind speed decreased about 16% in the immediate leeward side, as compared with the standard wind speed at -20H at each height due to the low net density of 15%; however, the effective decrease was continued over a long distance. Air, surface leaf and surface soil temperatures with right-angle wind increased significantly in the leeward side under conditions of weak wind, and this increase continued for more than 25H. The temperatures increased and relative humidity decreased during the daytime for 20H in the leeward side. Temperature increase is useful for growth and development of crops, vegetables and other vegetation. However, the harmful decrease of temperatures by surface inversion was measured from the night to early morning under conditions of a fine or clear day with weak wind. As the net density was low and not sufficiently effective, it will be necessary to introduce considerably higher windbreak net and to reduce the open space under the net. Moreover it will be necessary to obtain accurate data using different windbreak nets in the open field.View full abstractDownload PDF (903K) -
Hiromu DAIMARU, Hiroshi TAODA2004 Volume 60 Issue 4 Pages 253-261
Published: 2004
Released on J-STAGE: May 09, 2006
JOURNAL FREE ACCESSThe effect of the snow pressure on the distribution of A. mariesii forests on northern Honshu Island was examined by GIS-based analysis. A. mariesii forests prevailed in areas, where maximum snow depth is between 100 cm and 450 cm. In the snowy mountains where maximum snow depth exceeds 350 cm, the A. mariesii forest tends to be confined to relatively gentle slopes as snow depth increases. The future snowfall decrease projected by JMA RCM20 will accelerates the shift of A. mariesii forest to higher elevations in the Kitakami Mountains. On the other hand, release from extreme snow pressure on the relatively steep and snowy mountains on the Japan Sea side will not lead to extensive emergence of new A. mariesii forests because most of these mountains are significantly far from existing A. mariesii forests.View full abstractDownload PDF (1765K) -
Daisuke KOMORI, Masatoshi AOKI, Tomoyasu ISHIDA, Satoru SUZUKI, Takash ...2004 Volume 60 Issue 4 Pages 263-272
Published: 2004
Released on J-STAGE: May 09, 2006
JOURNAL FREE ACCESSThe major advantages of the true eddy accumulation technique are that it is a direct method for flux measurements and applicable to any trace gases which need either a slow response sensor or the installation of an adsorbent for condensation. However, it is difficult to accurately take the sample air with high time resolution according to vertical wind velocity and direction. Therefore, we have developed an air sampling system for the true eddy accumulation technique. The air sampling system is designed to take updraft and downdraft air samples in proportion to vertical wind velocity with high time resolution using syringes connected to a 40 Hz stepping-motor. The system is also designed to accumulate air samples in separate reservoirs for updraft and downdraft, and to convey air samples to the gas analyzer alternately to detect their gas concentration automatically. To test how precisely air samples are taken with high time resolution, the sample volumes by the system under conditions of different suction durations and input voltages were measured. The results of this experiment showed the system with the back flow route was able successfully to take air samples in proportion to vertical wind velocity on a base of 7 Hz considering the problem of suction errors. The preliminary test in a grass field showed that the accumulated sample volume during one measurement sequence was proportional to the amount of accumulated vertical wind velocity. The linear relations were recognized between CO2 flux measured using the system and that measured using the eddy correlation technique. These results lead to the conclusion the developed air sampling system for the true eddy accumulation technique is available to measure CO2 flux.View full abstractDownload PDF (713K)
Full Papers (in Japanese)
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Susumu NOZOE, Akira TANI2004 Volume 60 Issue 4 Pages 273-283
Published: 2004
Released on J-STAGE: May 09, 2006
JOURNAL FREE ACCESSAn automatic terpene gas sampling system was developed to obtain the terpene concentration gradient for flux determination. The system can collect terpene gases from two different sampling lines into different adsorbent tubes simultaneously. Eighteen adsorbent tubes can be set in this system. The holder of adsorbent tubes can be cooled or heated for keeping the tube temperatures constant, which can prevent change in adsorption efficiency of adsorbents affected by tube temperature. Adsorbent tubes can be changed by electrically actuated multiposition valves. Results of performance tests showed that there were no emissions of trace contaminants from the inside of sampling lines. The automatically sampling errors were lower than manual sampling errors. This means that automation of sampling is beneficial for lowering errors. The temperature of the 16 adsorbent tubes in the holder could be kept uniform. These performance tests showed that the system could be successfully used for terpene flux measurements above a plant canopy.View full abstractDownload PDF (3031K) -
Hisashi KON, Rui ICHIBAYASHI, Nobuhiro MATSUOKA2004 Volume 60 Issue 4 Pages 285-290
Published: 2004
Released on J-STAGE: May 09, 2006
JOURNAL FREE ACCESSMeasurements of global and diffuse UV-B radiation have been carried out in Matsudo City (35.3°N, 139.9°E), Japan. Forty clear sky days were chosen and the annual variation of global and diffuse UV-B radiation was analyzed. The dependence of the diffuse component on visibility was also examined. The results are summarized as follows. 1. The maximum of daily global UV-B was beyond 40 kJm-2day-1 and was recorded in late July. The maximum of daily diffuse UV-B was recorded in early July. There was a tendency for the diffuse UV-B to be larger than the direct UV-B during a year in Matsudo. 2. The fraction of diffuse UV-B to global UV-B changed a lot each day. The observed minimum value of the fraction during a year was recorded in early August. 3. There was a tendency for the fraction of diffuse UV-B to global UV-B to decrease when visibility increased. 4. The diffuse components that change a lot each day were properly estimated by using the expected minimum fraction and visibility.View full abstractDownload PDF (809K) -
Tomohiro HAJIMA, Yo SHIMIZU, Kenji OMASA2004 Volume 60 Issue 4 Pages 291-297
Published: 2004
Released on J-STAGE: May 09, 2006
JOURNAL FREE ACCESSThis study was conducted to determine the relationships between temperature and land use change in urban areas. The main object was to verify whether there is a direct relationship that could explain the change in temperature as a result of land use change in urban areas. Using the 11 meteorological stations in the Kanto District, the monthly records of maximum and minimum temperature from 1940 to 1997 were analyzed. At the same time, the land use maps of 1971 and 1997 were analyzed to determine the land use changes. In concentric circles with the meteorological station as its center, the number of grids that changed from arable and forest to urban land use was used as the indicator of land use change. The appropriate extent of land use change around a meteorological station was considered by varying the radius of the concentric circles from 1 km to 20 km. The average temperatures for two periods before 1971 and 1997 were respectively calculated, with the period for averaging varied, and the difference among them was regarded as the climatic warming corresponding to land use change between 1971 and 1997. The relationship between the climatic warming and the change in the number of urbanized grids was analyzed statistically, considering various combination of the radius of the concentric circles for monitoring urbanization and the number of years for averaging of temperatures for both periods. Results of the correlation analysis between maximum air temperature and change in land use showed a weak relationship. On the other hand, a significant positive correlation between minimum temperature and change in land use was found by taking the average of monthly mean temperature for 20 years and using the land use indicator calculated at 20 km radius.View full abstractDownload PDF (1140K)
Short Papers (in Japanese)
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Takanori YAMAMOTO, Shinya OKUYAMA2004 Volume 60 Issue 4 Pages 299-306
Published: 2004
Released on J-STAGE: May 09, 2006
JOURNAL FREE ACCESSThe main purpose of the present study is to develop a simple method of measuring a parameter which is necessary for a radiation distribution model of fruit tree canopies (OLEAS), and which estimates extinction of photosynthetic active radiant flux density originating from derived diffused light (PARFDdd) within the disorderly distributed leaves. Using shoots of several deciduous fruit trees, the disorderly distributed leaves with various LAI were formed in a device made of two tubes. When direct sunlight went to one tube containing the leaves, the PARFDdds were measured, and averaged (I′). Here the PARFDdds were extracted from a waveform of the output containing direct sunlight. The direct PARFDs from another empty tube were measured, and averaged (Io). I′/Io of each variety was distributed from 0.8% to 5.3%, when LAI was about 1. In many varieties, the decrease of I′/Io became gentle when LAI exceeded about 3. There was a low and negative correlation between mean value of I′/Io and SPAD (mean relative concentration of chlorophyll) of the leaves. When I′/Io was approximated with LAI, LAI2 and LAI3, the contribution ratio (R2) of the equation of each variety was high generally, and was mostly over 0.94.View full abstractDownload PDF (1290K)
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