Relationship between growth of young cryptomeria japonica on a mountain slope and spatial differences of moisture and nutrients
2010
Yamamoto, T., Tokyo Univ. (Japan) | Asano, Y. | Hotta, N. | Suzuki, M.
It is important to clarify the major environmental factors and mechanisms that determine the growth of Cryptomeria japonica planted on mountain slopes. We investigated the growth of young C. japonica, the spatial differences and temporal changes of soil moisture and inorganic nitrogen concentrations in soils along the slope and then considered the relationship between the growth of young C. japonica and the differences in moisture and nitrogen of soils in the Fukuroyamasawa experimental watershed. The growth of C. japonica was faster on the valley bottom than on the ridge. Volumetric water content of the surface soil was higher and saturated groundwater occurred more frequently near the valley bottom. The average concentrations of nitrogen in current-year leaves and the inorganic nitrogen in soil water and groundwater were higher at the valley bottom; while there were no significant differences in total nitrogen concentration and soil C/N ratio for different positions on the slope. Inorganic nitrogen is generated from organic matter by microorganisms and the soil moisture regime affects microbial activity. The spatial difference in the soil moisture regime along a slope should affect the growth of young C. japonica directly and indirectly by affecting soil the nitrogen mineralization activity of microorganisms.
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