The Land Improvement Low, as amended in 2002, stipulates that agricultural practices should not damage the surrounding environment; hence, there is a growing need for quantitative measures of the impact on lake ecosystems of changes in use of agricultural land. In particular, paddy fields, which function directly as areas where fish breed and spawn, may also be having an indirectly adverse effect on fish ecology through water pollution that results from the use of fertilizers and agricultural chemicals. To investigate this possibility, the present research focuses on the Lake Kasumigaura catchment basin. We applied path analysis (a type of graphical modeling effective in the analysis of cause-and-effect relationships featuring both indirect and direct effects), constructed statistical models of the lake ecosystem centering on fish species, and quantitatively clarified the impact on the lake ecosystem attributable to changes in the use of agricultural land. We first carried out, by means of factor analysis,verification of conceptual models based on a qualitative rationale; then constructed a path diagram relating to the lake ecosystem and carried out path analysis; and lastly, identified which models fitted best.The results obtained show that changes in the area of paddy fields cause a standardized overall eccect of 0.331 on loaches and 0.079 on crucian carp, indicating quantitatively that loaches are more susceptible than crucian carp to the impact of changes in agricultural land use. The present research has also shown the potential for applying graphical modeling to the assessment of the impact on lake ecosystems of changes in the use of agricultural land.
The characteristics of air temperature distribution in Kamogawa Okayama Prefecture, were estimated by means of a stepwise multiple regression analysis. A comparison was then made between the distribution of monthly air temperature based on maps with 50 m and 1 km mesh sizes. Our objective was to discuss suitable land use for agriculture based on the regional air temperature distribution. The regression analysis suggested that the distribution of maximum monthly air temperature is mainly determined by mean elevation in all seasons. However, the distribution of minimum monthly air temperature was primarily determined by mean elevation only during summer; at other times, other factors must be considered. It was also found that the minimum monthly air temperature is comparatively high in valleys having large rivers. The distribution of maximum monthly air temperature on the 50 m and 1 km meshes was similar in all seasons. Notably, the average difference between maximum monthly air temperatures on the 1 km mesh was over 1 ℃. The distribution of minimum monthly air temperature on the 50 m and 1 km meshes differed noticeably at higher elevations during seasons other than summer. The thermal belt did not appear in the 1 km mesh maps of minimum monthly air temperature at those times.
Human society must establish a sustainable recycling-based society. It is difficult to carry out organic waste recycling without developing regional agriculture with an organic-waste recycling function. Therefore, conversion to a sustainable recycling-based society from the current conventional resource waste-based society demands reconsideration of the role of regional agriculture. We present the Tachikawa-machi organic waste recycling system as an example of organic waste recycling which is compatible with regional agriculture development. We analyzed the mutual relation of the Tachikawa-machi compost production center, homes, livestock farmers, and rice crop farmers. We also analyzed system maintenance costs and their meaning. Organic waste flows in this system are 'Regional collection - Regional recycling - Regional use'. Tachikawa-machi residences' entire quantity of kitchen garbage was composted. Tachikawa-machi rice crop farmers used all of resultant compost. They needed to develop regional agriculture to increase the quantity of compost that rice crop farmers used because the compost production quantity was related to the quantity of compost used. Consequently, the organic rice production quantity that rice crop farmers produced increased concomitant with the increase in compost production quantity. We witnessed regional agriculture development as livestock farmers' costs decreased and rice crop farmers' income increased. The Tachikawa-machi organic waste recycling system solved a difficult problem by conjoining processes of homes, livestock farmers, and rice crop farmers. This system is maintained through annual payments of about 23,960,000 yen by Tachikawa-machi. We witnessed effects including: systemic kitchen garbage disposal costs cut about 4,030,000 yen, rice crop farmers' income increased about 25,610,000 yen, decreased livestock farmers' costs, and a higher recycling rate in Tachikawa-machi.
We investigated the influence of country size on the cereals self-sufficiency ratio. The primary research task was to clarify the details and sources of the scale effect at the country-level, which were not presented in precedent studies. We employed a cross-country analysis using the country-level aggregated data of 157 countries in the period ranging from 1994-98. Population appears to be an appropriate proxy of country size in analyzing the determinants of the cereals self-sufficiency ratio. A regression analysis of the self-sufficiency ratio clarifies that population contributes positively to the self-sufficiency ratio, while controlling for arable land per capita and GDP per capita. While controlling for explanatory variables other than population, in the regression analysis noted above, the partial correlation analysis revealed that large countries achieve a high self-sufficiency ratio with a pattern similar to import substitution; the pattern involves production increase by land-saving, while ensuring the same level of supply per capita as that of small countries. It is also revealed that (i) the scale effect is external at the country-level; (ii) the scale effect promotes self-sufficiency; (iii) the scale effect does not contribute to a competitive advantage;and (iv) transportation cost is not the primary cause of the scale effect. These features of the scale effect suggest policy intervention, especially agricultural support. In fact, using another dataset of 26 countries in the period ranging from 1982-87,the regression analysis of agricultural support (%PSE of cereals) reveals a positive partial correlation between population and %PSE. Our results do not correspond with what is generally considered as the sources of the country-level scale effect in international trade economics. We interpret them as given below. A larger country faces a stricter supply constraint in the international cereals market; the supply constraint on imports and the security-related concern increase self-sufficiency orientation; and self-sufficiency orientation is reflected in a higher agricultural support level.
Unmanaged bamboo forest worsens the landscape of relative regions and river basin ecosystems. Besides this, its consistent expanding could erode artificially planted forest resources and agricultural fields, and may also induce some serious environmental problems. In this study, the distribution of bamboo in the surrounding areas of Gifu-city, with a total area of 14,280 ha, was extracted using the decision tree classifier method and the maximum likelihood classifier method, respectively. For this purpose, high-resolution satellite IKONOS data and mediate-resolution satellite Landsat ETM+ data were utilized, along with fusion images generated using IHS conversion based on both satellite data. Using field-surveyed results, the accuracy of the classification was assessed. In five data sets of Landsat ETM+ acquired in different seasons, the ETM+ data acquired in March was found to be the best bamboo classification (with 61.9% of precision). By applying generated fusion images, the classification precision was improved as much as 84.9%, i.e., a level higher than individual use of either IKONOS or Landsat ETM+ data. Moreover, based on fusion images, the bamboo distribution area was estimated to be 89.6 hectares in the study area.