造林II－Ａ

401	スギ樹幹の肥大成長開始と気温
玉泉幸一郎（九大農院）	スギの幹形成層の分裂開始と気温との関係を明らかにするために、異なる標高に生育するスギ林分において、幹肥大成長と気温を測定した。測定は２００１，２００２年の２カ年行った。標高と年別の成長開始時期の違いから、スギ肥大成長開始と温度との関係を解析し報告する。

402	欠

403	The effect of weed control on the root developmentof Senna siamea in ASALs
Bernald K. Kigwa 矢幡　久（九大院）	In a semi-arid area, it is very difficult to grow seedlings healthily by the normal weed control such as slashing and spot weeding. We found that the eradication of weeds (completely weeding) could enhance both the survival rates and the seedling growth. In addition to the faster growth, the seedlings treated by complete weeding were less water stressed, although the transpiration rates and stomatal conductance were fairly high compared to those treated by slashing. In his study, the root systems of both treatment plots were compared 20 months after planting. At each plot, the soil profile of 10 m width and 1.7m depth was exposed at three different distance, i.e., at 1 m interval from the three trees line. The root densities were measured by taking more than 400 photos per profile and by use of computer software. The effects of weed control on the root density and root biomass were examined to clarify the importance of the eradication of weeds in ASALs.

403

The effect of weed control on the root developmentof Senna siamea in ASALs

Bernald K. Kigwa
矢幡　久
（九大院）

In a semi-arid area, it is very difficult to grow seedlings healthily by the normal weed control such as slashing and spot weeding. We found that the eradication of weeds (completely weeding) could enhance both the survival rates and the seedling growth. In addition to the faster growth, the seedlings treated by complete weeding were less water stressed, although the transpiration rates and stomatal conductance were fairly high compared to those treated by slashing. In his study, the root systems of both treatment plots were compared 20 months after planting. At each plot, the soil profile of 10 m width and 1.7m depth was exposed at three different distance, i.e., at 1 m interval from the three trees line. The root densities were measured by taking more than 400 photos per profile and by use of computer software. The effects of weed control on the root density and root biomass were examined to clarify the importance of the eradication of weeds in ASALs.