The forest steppe in Mongolia lies between the taiga forests and the steppe grasslands, in moister conditions than steppe grasslands. Forest steppe encompasses both coniferous forests and grasslands, each with a unique distribution pattern. This geographical diversity supports biodiversity, giving the forest steppe great value. Although there are many studies of the vegetation of forest steppe, few studies relate vegetation to soil properties. The objective of this study was to clarify the characteristics of soils under the forest steppe in Mongolia. The study was carried out at four sites in Gorkhi-Terelj National Park. We investigated the soil profiles under grassland on a south-facing slope (TER-G) and on a ridge (TER-T), under forest on a north-facing slope (TER-F1) and under dense forest on a north-facing slope (TER-F2). We analyzed soil organic carbon, total nitrogen, pH (H₂O, KCl), exchangeable bases, CEC and humic substances. Two soil-vegetation associations were identified. On Phaeozems characterized by a high C content and high base saturation ratio, the A horizon became thicker, the humic C to fulvic C ratio increased, and the ratio of humic acid to humic + fulvic acids increased as the vegetation changed from forest to grassland. In contrast, Umbrisol was characterized by a low C content, a high C/N ratio and a low base saturation ratio.

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眼高差測定器を用いて海面付近の気温の鉛直傾度を通常用いられる方法, すなわち温度計を配置して測るよりも高い精度 (約0.01℃/m) で測定した. この方法のもう一つの利点は, 外洋を航行中の船上から測定出来るから, 短期間に, かつ容易に広い外洋から多くの資料が集められることにある. 北海道大学練習船おしよう丸の2回の航海中で得られた, ベーリング海からオーストラリア南方海域にわたる125点の眼高差の測定値を用いて, 気温の鉛直傾度を計算した.この計算のために, 空気の屈折率が海面上の高さだけの画数であるという仮定だけで計算するための式を導いた. 北太平洋北部では気温の傾度は正, 亜熱帯および熱帯太平洋では正も負も観測された. 一般に同一の海域では気温と水温との差に関係なく気温の鉛直分布は同じ型を示すことが見出された.

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The grey mangrove (Avicennia marina (Forsk.) Vierh.) in per-arid areas on the Red Sea coast is characterized by its tree morphology, as branches tend to extend laterally rather than upward and often carry adventitious roots on their main axis. To test the hypothesis that such branch morphology is linked with the water-use characteristics in leaves, the relationships between morphological parameters of branch and carbon isotope ratio of leaf organic matter at the branch top (δ¹³Com) were examined in 12 trees growing in a 5 × 10 m plot on the shoreline fringe of a stand at Hamata, Egypt. The δ¹³Com was significantly correlated with the sloped branch length between the base and the tip (L) and the adventitious roots and the tip (Lr) when L or Lr < 700 cm, but not with the vertical height of the branch (H). Furthermore, the δ¹³C_om was more strongly correlated with Lr than with L. These results suggest that the intrinsic water-use efficiency of leaves can be linked to the actual path length of water transport from water absorptive roots to leaves and that the leaves of these A. marina trees can enhance intrinsic water-use efficiency in response to decreasing hydraulic conductivity of xylem by elongating branches. Moreover, lateral branches with adventitious roots may also act to improve the hydraulic conductivity of xylem. These two factors account for the survival of A. marina trees growing in per-arid areas along the Red Sea coast.

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