Ecophysiological studies on the mechanisms for appearance and disappearance of species in successional stages.

对日本暖温带常见演替过程中的3个生态场景：1.水生生境中物种的循环更替；2.嗜日树种入侵芒草草原；3.在早期次生演替过程中，先锋树种从种子中重新出现、更新和消失的机制进行了研究。对植物群落内光环境的时间和微观空间异质性进行了详细的测量，以评估某一物种幼苗能够在其中存活和建立的微站点的分布。对入侵芒草草原的代表性树种锯缘栎种、喀苏木湖物种更替中的水生植物莲子和日本莲子，以及在森林砍伐或火灾后立即出现的典型拓荒者爪哇树和海棠进行了与生长繁殖相关的各种生理和生活史参数的测定。主要研究结果和结论如下：1.水生植物异生叶的生物量分配和寿命似乎对水生生境中二维生活空间的种内和种间竞争和占据起着重要作用。2.在芒花冠层内，光有效性具有很大的微观空间异质性。虽然锯缘栎实生苗存活和建立的光能利用率较高的微立地相对较多，但个体幼苗的存活和生长取决于微立地的光能利用率水平，种子大小和对遮荫的形态和生长反应对物种成功入侵草地具有重要的生态学意义。3.对先锋树种种子萌发的林隙检测可以有效地提高林隙中的苗木适合度。

Mechanisms for successional appearance, replacement.and disappearance of species were studied for three ecological scenes in common Successional processes in warm-temperate Japan: 1. cyclic replacement of species in anaquatic habitat; 2. invasion of heliophilic trees into Miscanthus sinensis grassland; 3. recruitment of pioneer trees from seeds in early secondary succession. Detailed measurements on temporal and micro-spatial heterogeneity of light environment within plant communities were performed to evaluate the distribution of the microsites in which seedlings of a certain species can survive and establish. Various physiological and life-history parameters associated with growth and reproduction were measured for Quercus serrata, a representative species invading into Miscanthus sinensis grassland, Nelumbo nucifera and Nuphar japonicum, the aquatic plants involving in the cyclic species-replacement in Lake Kasumigaura, and Rhus javanica and Mallotus japonica, typical pioneers appearing immediately after forest clearing or fire. The main results and conclusions are: 1. Biomass allocation and longevity of heterophylous leaves in the aquatic plants seem to play important roles in intra- and interspecific competition and occupation of two-dimensional life space in an aquatic habitat. 2. There is a great micro-spatial heterogeneity in light availability, within a Miscanthus sinensis canopy. Although, the microsites with 'Permissible light-availability levels for survival and establishment of Quercus serrata seedlings are relatively abundant, the survival and growth of the individual seedlings depend on the light availability level of the microsite. The large seed size and the morphological and growth responses to shading have important ecological significances in successful invasion of the species into the grassland. 3.Gap-detection in seed germination of pioneer tree species can effectively raise seedling fitness in gaps.