| Budget Amount *help |
¥4,290,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥990,000)
Fiscal Year 2015: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2014: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2013: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
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| Outline of Final Research Achievements |
This study examines how the flora and species diversity of rice paddy weeds have changed on the basis of differences in rice paddy management over time. We used Shannon diversity index and rarefaction curve to estimate the past weed diversity detected from archaeological weed remains.The results indicate that the weed diversity increased from Ancient period and the highest diversity was recorded at Medieval times. The new methods of paddy field management introduced from these periods probably caused the intermediate-disturbance. From the Edo period, the weed diversity decreased gradually, and it is decreased drastically from Showa period. Not only use of agricultural chemical but also the decreasing of water table is main cause of the decrease of weed diversity. The weed diversity, however, re-increasing in the small-valley paddyfield without use agricultural chemical in the Heisei period.
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