Comparative study on ecological chracteristics of seedlings between Fagus crenata and Fagus japonica.

为了解水青冈（Fagus crenata，Fc）和日本水青冈（F.japonica，Fj）当年生幼苗在林下的建苗过程，比较了它们当年生幼苗的生态特征。调查了不同光照条件下的幼苗生长量和光合能力。2种树种的生长年限主要取决于幼树的年龄和母树年轮的生长规律。1.春季林地光照条件好，幼苗有子叶，夏季光照条件差。Fe的幼苗存活率高于Fj。2.种间在物候和形态上存在差异，Fj的子叶较大，寿命比Fc长一倍以上，Fj的叶片较薄，较舒展，出苗较晚。在遮荫条件下，两个物种的子叶寿命都较长。 ...更多信息 3.在任何光照条件下，物种之间的总生物量没有显着差异。在较好的光照条件下，Fj比Fc分配更多的干物质到地上部。Fe的最大光合速率和净同化率均高于Fj。结果表明，两种植物在光资源利用上存在一定的相对趋势，其中，Fc具有较高的光合能力灵活性，而Fj具有较高的形态灵活性。4.两种植物子叶的光合特性与典型阳生叶相似，最大光合速率与叶片相当。5.近25年来，Fe和Fj的光合生产年数分别是Fe和Fj的7倍和6倍，且种间不同步。结果表明，两种树种的树干肥大与径向生长之间存在显著的相关性，且可以从年轮格局中确定过去的肥大年份。少

Ecological characteristics of current-year seedlings were compared between co-occurred Fagus crenata (Fc) and F.japonica (Fj) to understand the process of seedling establishment on the forest floor. Seedling populations were censused and growth of the seedlings under different light conditions, and photosynthetic capacity were surveyed. Mast years of both species were determined by age of saplings and growth patterns of annual rings of mother trees.1.Light condition on the forest floor was favorable in spring when the seedlings had cotyledons and severe in summer. Survival of the seedling of Fc was higher than Fj. Mortality of seedlings was in part due to grazing by insects.2.Differences between species in phenology and morphology were observed ; cotyledons of Fj were larger and their longevity was longer (more than twice) than Fc, leaves of Fj were thinner and more spreading and emerged later than Fc. The longevity of the cotyledons was longer in more shaded condition in both species. … More 3.There were not significant differences in total biomass between species in any light conditions. Fj was allocate more dry matter to aerial parts than Fc in more favorable light condition. Maximum photosynthetic rate of Fc was higher and net assimilation rate was higher than Fj. These showed relative trends in light-use of each species ; Fc uses different levels of light resource efficiently by higher flexibility in photosynthetic capacity while Fj by higher morphological flexibility.4.Photosynthetic characteristics of cotyledons were similar to those of typical sun-leaf in both species and maximum photosynthetic rate was comparable to that of leaves. Photosynthetic production by cotyledons was not negligible in annual net production of Fc and more important in Fj.5.Mast years during resent 25 years were 7 times in Fc and 6 times in Fj, and not synchronous between species. Significant correlation between masting and radial growth of trunk was observed in both species, and mast years in the past was capable to be determined from the annual ring patterns. Less