著者

菊沢 喜八郎

出版者

日本生態学会

雑誌

日本生態学会誌 (ISSN:00215007)

巻号頁・発行日

vol.30, no.4, pp.359-368, 1980-12-30

被引用文献数

4

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Leaf-fall pattern of six alder species (subgenus Gymnothyrsus : Alnus hirsuta, A. inokumae, A. glutinosa, A. japonica ; subgen. Alnaster : A. maximowiczii, A. pendula) was investigated from 1976 to 1979. A large quantity of leaves of the species belonging to the subgen. Gymnothyrsus fell in summer, which reached 30-50% of the yearly leaf fall. The first, second and/or the third leaves counted from the shoot base of these species almost fell in summer. These two or three leaves near the shoot base are small-sized, which indicates that these leaves are in course of reduction, and they fall early in summer after they have played a role as early leaves. In the subgen. Alnaster, the lamina of the first node is reduced and disappeared, and the remaining two stipules are connate in a bud scale which fall in late spring or early summer after it has played a role of the bud protection, while the leaves did not fall until autumn. Thus the extraordinary leaf fall in summer was not observed on the species of this group, and it was less than 10% of the total fall.

著者

菊沢 喜八郎

出版者

日本生態学会

雑誌

日本生態学会誌 (ISSN:00215007)

巻号頁・発行日

vol.36, no.3, pp.189-203, 1986-12-31

被引用文献数

9

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Existing literature on seasonal replacement in forest tree-leaves was reviewed from the viewpoints of phenology, leaf biomass, leaf fall, leaf survivorship-curves and defoliation by insects. Many of the investigations which had focused on phenological and leaf fall analyses were found to be inadequate to obtain accurate information about the life span of individual leaves. Life table analysis of leaves should be introduced into this type of investigation in order to construct an economic life table from a combination of life-tables with photosynthetic or respiratory activities. Leaf longevity is considered to be determined by the balancing of the cost of leaf construction, leaf maintenance, and the benefit or photosynthetic gain from the leaves. Therefore, leaf longevity is one adaptive strategy of plants to environmental conditions. The leaf survival strategy of pioneer species is characterized by long term leaf-emergence and short leaf-longevity, whereas tree species which are members of climax forests show simultaneous leaf-emergence and leaf-fall. Leaf longevity of forest-understory species is usually long. Leaf survival strategies are considered to have resulted from the evolutionary adaptive radiation of each species to various environments, accompanied by the evolution of morphological features such as shoot structure.