Spatial variations in needle nitrogen content in sugi (Cryptomeria japonica D. Don) plantations across Japan
2008
Shigenaga, H.(Forestry and Forest Products Research Inst., Kumamoto (Japan). Kyushu Research Center) | Takahashi, M. | Nagakura, J. | Akama, A.
For a general assessment of the nitrogen status of sugi plantations in Japan, we measured nitrogen content in the needles of sugi (Cryptomeria japonica D. Don) trees growing at 531 sites across the country. We attempted to find local pockets with high or low needle N and to ascertain the relationships between needle N and temperature, the rainfall environment or latitude. Average needle nitrogen content was 14.0 mg N/g with half the sites ranging from 12.5 mg N/g to 15.5 mg N/g; a level thought to be reasonably appropriate. Spatial analysis using Gsub(i)sup(*)(d) statistics showed a spatial autocorrelation and indicated that needle N contents were high in two areas. These were in and around Fukui Prefecture and in the western part of the Kii Peninsula. Contrarily, needle N content was low in the mid-Tohoku district. The relationships between needle N and temperature or rainfall environment or latitude were weak. Thus, these factors cause little variation in needle N in sugi plantations across Japan.
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