森林立地学会誌  森林立地 52(1),2010,1〜10

Jpn.J.For.Environment 52(1),  1-10  2010

 

斜面部位による土壌呼吸量の空間変動

―熊本県北部のスギ，ヒノキ林の場合―

 

玉井幸治^１・清水貴範^１・大貫靖浩^２・石塚成宏^１

^１独立行政法人森林総合研究所・^２独立行政法人森林総合研究所九州支所

 

熊本県山鹿市鹿北町に位置する鹿北流域試験地で，標高差４０ mの南向き斜面に，頂部，上部，中部，下部の４プロットを設営し，土壌呼吸量を測定した。また土壌含水率や地温のモニタリング観測も併せて行った。各プロット間で，大きな地温の違いは認められなかったが，土壌含水率は大きく異なり，斜面の下方になるほど湿潤であった。４プロットで算出された年間土壌呼吸量を比較すると，下部では６割程度と少なかった。その原因は，土壌特性の違いに起因する抑制効果が，土壌の湿潤による土壌呼吸の促進効果など上回ったためと考えられた。

 

Koji Tamai, Takanori Shimizu, Yasuhiro Ohnuki and Shigehiro Ishizuka：Topographical variation of soil respiration in a warm-temperate evergreen forest in Kumamoto Prefecture, western Japan. Japanese Journal of Forest Environment 52:1−10, 2010.

The soil respiration rate was measured in four plots in different topological locations at the top, upper, middle, and base of a southfacing slope in the Kahoku Experimental Watershed, located in Yamaga, Kumamoto Prefecture. The soil moisture content ratio and soil temperature were also monitored. No large difference in soil temperatures was recognized among the four plots. By contrast, very large differences in soil moisture were found in the four plots. The soil was wetter in the plots located lower on the slope. The estimated annual soil respiration rate was much lower（around 60％）in the base plot, compared with the middle plot. This was thought to occur because the decelerating effect of soil characteristics on soil respiration exceeded the accelerating effect of wetter soil.