2007 Fiscal Year Final Research Report Summary
Estimating function of earthworm communities based on stoichiometry
| Project/Area Number |
18510021
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental impact assessment/Environmental policy
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| Research Institution | Yokohama National University |
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Principal Investigator |
KANEKO Nobuhiro Yokohama National University, 大学院・環境情報研究院, Professor (30183271)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Stoichiometry / Decomposer system / Soil fauna / Nitrogen to Phosphorus ratio / Forest soils / Earthworm life form |
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| Research Abstract |
Human activities are now changing global nitrogen and phosphorus cycling in ecosystem as well as climate. Earthworms are soil ecosystem engineers modifying litter decomposition and soil physical structures. Climate change and disturbances in ecosystem cycling of N and P due to atmospheric nitrogen deposition and fertilization may change community structure of soil animals, especially, earthworms, because N and P are often limiting nutrients in terrestrial habitat. I studied N and P contents in soil and earthworms and tried to estimate ecosystem level effects of disturbance in NP balance.
Soil N mineralization rates were greatly enhanced by the presence of earthworms, thus not only soil microorganisms but also earthworms are nitrogen driver. Defoliation of Sasa leaves in a field condition promoted soil micro-food web starting from root exudation, and then soil bacteria and bactrivorus nematodes were observed to change. Finally nitrogen mineralization was enhanced.
Leaf quality affected earthworm growth in a field microcosm condition, and also there was a good correlation between body N:P and growth of Japanese earthworms. Epigeic earthworms had high growth rate and low N:P, and in contrast to this, endogeic species are slow grower and had high N:P. N and P are thus important determinant for community structure of earthworms.
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