Agriculture Reference
In-Depth Information
Symplocos prunifolia
Machilus thunbergii
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1994
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Fig. 5.3 Survivorship curves for different cohorts of leaves in two co-occurring evergreen broad-
leaf trees, Symplocos prunifolia ( left ) and Machilus thunbergii ( right ). Log leaf number is plotted
against calendar months. Open circles , leaves that appeared in 1995; open squares , leaves that
appeared in 1994; open triangles , leaves that appeared in 1993; inverted triangles , leaves that
appeared in 1992. (From Nitta and Ohsawa 1997)
Japan. Leaf longevities ranged from 1.5 to 4.3 years, quite similar to the range
of 1.4 to 3.8 years reported for 16 species of broad-leaved evergreen dwarf
shrubs from Europe (Karlsson 1992). In the Japanese forest, the leaf longevity
of Symplocos prunifolia was 1.5 years, with leaves emerging each spring but
only being shed during spring and summer the next year (Fig. 5.3 ). In Machilus
thunbergii with a mean leaf longevity of 2 years, the emergence of leaves in
spring is more or less simultaneous with shedding of the 2-year-old leaf
cohort, although the period of leaffall can be somewhat longer (Nitta and
Ohsawa 1997). A similar pattern prevails in Castanopsis cuspidata, Quercus
myrsinaefolia , and Quercus acuta . In S. prunifolia, Illicium religiosum , and
Cleyera ochnacea , whose leaf emergence period was long, leaffall period was
also long. Eurya japonica usually shows several periods of leaf emergence
within a year, which are coordinated with periods of leaf shedding. This cor-
respondence in the timing of leaf emergence and leaffall is associated with
translocation of resources from senescing to emerging leaves (Nitta and
Ohsawa 1997). Navas et al. (2003) studied the leaf longevity of 42 plant spe-
cies in the Mediterranean region of south France, including some evergeen
trees. Leaf longevities of the evergreen trees ranged from 488 to 802 days.
Mediavilla and Escudero (2003b) reported leaf longevities of evergreen
Quercus coccifera , Q. rotundifolia , Q. suber , and Ilex aquifolium to be between
1 and 2 years in western Spain.
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