Effect of cultivation methods in a controlled mixing tillage of plow layer on habitat condition of the genus Sympetrum
2006
Jinguji, H.(Akita Prefectural Univ., Ohgata (Japan)) | Tashiro, T. | Sato, T. | Tsuyuzaki, H. | Kondo, T.
The study was conducted in no-till, no-puddling and conventional cultivation method rice field, respectively. We investigated larval development; emergence species and emergence patterns of Sympetrum in each rice field. The following results were obtained:1. larval dragonfly populations in no-till and no-puddling rice field were higher than than those in conventional rice field 2. During 5 year period, the number of exuviae collected per 50m2 in no-till, conventional no-puddling cultivation methods were 75l, 4,422, 4,272 respectively. Especially Sympetrum frequens was the most abundant species in no-puddling rice field. 3.Larval composition of each dominant species (S. infuscatum, S.frequens, S. darwinianum) in conventional and no-puddling cultivation method was characterized by a constant percentage throughout 5 years. S. frequens were dominant species in no-till cultivation rice field at first year, but after two years S. infuscatum became the most abundant species. We have shown that disturbance for puddling decreased larvae of Sympetrum and individuals of S.frequens decrease in no-till cultivation rice field.
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