Endogenous Influences on Leaf Longevity - Ecology of Leaf Longevity - page 81

Variation of Leaf Longevity with Timing of Leaf Emergence

Leaf longevity can vary among different leaf cohorts within individual plants. In Betula
species, the leaves that emerge initially in early spring and leaves that emerge succes-
sively until summer differ in morphology (Kozlowski and Clausen 1966), photosyn-
thetic traits (Koike and Sakagami 1985; Koike 1990; Miyazawa and Kikuzawa 2004),
and their parent shoot morphology (long and short shoots: Yagi and Kikuzawa 1999;
Yagi 2000; Ishihara and Kikuzawa 2004). Longevity for early leaves in Betula grossa
was around 160-180 days, significantly longer than the 110-130 days for late leaves
(Miyazawa and Kikuzawa 2004). Similar structural differentiation of long and short
shoots was also observed in Halimium atriplicifolium , but leaf longevity on long shoots
of this Mediterranean subshrub was only marginally longer than on short shoots,
13.2 versus 10.6 months (Castro-Diez et al. 2005). Adenostoma fasciculatum , a shrub
of Mediterranean regions in North America, also has short shoots and long shoots
but with leaves on long shoots living only a year compared to 2 years on short shoots
(Jow et al. 1980). Leaf longevity on the Asian vine Akebia trifolia varied from less than
10 days to more than 1 year, irrespective of emergence timing (Koyama and Kikuzawa
2008). In wild strawberry, Fragaria virginiana , leaves emerging in early spring had
longevities of about 60 days compared to 130 days for those emerging in early summer
and 250 days for those emerging in fall and overwintering (Jurik and Chabot 1986).
Sydes (1984) observed similar contrasts in other herbaceous species between leaves
produced early in the growing season with longevities about 60 days compared
to 200 or even 300 days in leaves produced in fall and overwintering (Fig. 7.4 ).

Leaf lifespan

Mar 1, 2005 365 Days

Nov 1

Jul 1

Mar 1, 2004 0 Days

Nov 1

Jul 1

Mar 1, 2003
Mar 1, 2003 May 1 Jul 1 Sep 1

Date of leaf emergence

Nov 1 Jan 1, 2004 Mar 1

Leaves on secondary growth shoots

Leaves on short shoots
Leaves on long shoots +

Mean daily temperature < 5  C

Fig. 7.4 Date of leaf appearance, date of leaffall, and resulting longevity for individual leaves of
Akebia trifoliata ( n = 1,423). The two oblique lines are isoclines for leaf lifespan of 0 and 365
days, respectively. Shading indicates period unfavorable for photosynthesis. (From Koyama and
Kikuzawa 2008)