Ecophysiological Studies of Broad-leaved Deciduous Trees in Cool-warm Temperate Transition Zone

在小川自然森林科学保护区（36^ 55′n, 140^ 35′e）研究了阔叶落叶乔木（Fagus crenata， F. japonica, Srbus alnifolia， S. japonica, Styrax obassia）和灌木（Vaccinium oldhammi, Rhododendron semibarbatum， R. obtusum vart kaempferi, Vivurunum wrightii， V. phlebotrichum, Hydrangea hirta）共生幼树的生态生理，以及F. Fagus crenata和F. japonica的物候、光合作用和冠层结构。1980年和1981年在茨城县最北端。2年平均气温为10.8^ C。4月上旬，林冠乔木叶片未展开时，两样地PAR （RLI）相对光强分别为灌木层以上的70%和林底的65%，6月中旬，两样地PAR （RLI）分别下降了7%和3%。通过田间水关系的日常过程和实验室光合作用的测量，得到了以下结果：(1)蒸腾速率与水力导度呈正相关。(2)对水分胁迫有两种响应：一种是通过增大细胞壁体积弹性模量（epsilon）来躲避干旱，另一种是抗旱；这些物种有低的。(3)气孔对空气-叶片水汽压差敏感。(4)强光条件下气孔关闭对光合能力影响不大，光饱和光合速率较低。结果表明，油豆与粳稻在生态特性上存在以下显著差异。(1)两种植物物候特征相同。(2)绿皮菊的光饱和光合速率和光补偿点均高于粳稻。(3)金银花的冠层结构比金银花平坦，叶面积指数低于金银花。这些结果表明，两种植物的比较结果表明，金银花属植生植物，金银花属植生植物。少

Ecophysiology of co-occurring saplings of broad-leaved deciduous trees (Fagus crenata, F. japonica, Srbus alnifolia, S. japonica, Styrax obassia, Fraxinus lanuginosa) and shrubs (Vaccinium oldhammi, Rhododendron semibarbatum, R. obtusum var. kaempferi, Vivurunum wrightii, V. phlebotrichum, Hydrangea hirta), and the phenology, photosynthesis and canopy architecture of Fagus crenata and F. japonica were studied at the Ogawa Scientific Reserve for Natural Forest (36^ﾟ55'N, 140^ﾟ35'E), northernmost part of Ibaraki Prefecture in 1980 and 1981.The annual mean air temperature of two years was 10.8^ﾟC. Relative light intensity of PAR (RLI) in early April was ca. 70% above the shrub layer and 65% at the forest floor, when the leaves of canopy trees did not unfold, and in mid-June the RLIs of two plots decreased in 7 and 3%.Through the measurements of daily courses of water relations in the field and photosynthesis in the laboratory, the following results were obtained. (1) There was a positive … More relationship between transpiration rate and hydraulic conductance. (2) There was two responses against water stress : one was drought avoidance by enlarging bulk modulus of elasticity of cell wall (epsilon) and the other was drought tolerance ; those species had low epsilon. (3) Stomata were sensitive to air-leaf water vapor pressure deficit. (4) Closing of stomata under high light conditions hardly influenced the photosynthetic capacity because of low light-saturated photosynthetic rate. The following distinct differences of ecological characteristics of Fagus crenata and F. japonica were made clear. (1) The phenology of both species was the same. (2) Light-saturated photosynthetic rate and light compensation point of F. crenata were higher than those of F. japonica. (3) The canopy architecture of F. japonica was more flat than that of F. crenata and F. japonica had a lower leaf area index. These results suggested that comparing two species F. japonica was sciophyte and F. crenata was heliophyte. Less