Agriculture Reference
In-Depth Information
The extant gymnosperms, a lineage tracing back to the Middle Devonian some
365 million years ago (MYA), have their greatest diversity in the Southern
Hemisphere, but it is the species in the Northern Hemisphere that are best
studied (Enright and Hill 1995). Lusk (2001) reported a few leaf longevities
for Southern Hemisphere species ranging from 4.2 years for
Saxegothaea
conspicua
and 7.3 years for
Podocarpus nubigena
on up to 23.9 years for
Araucaria
araucana
and 32 years for
Podocarpus saligna
. Species in the genera
Abies
,
Pinus
,
Picea
, and
Larix
are good examples of the northern conifers, which most
often are evergreen trees with fairly long-lived needle- or scale-like leaves.
In the genus
Pinus
, leaf longevities can range from as short as 1.5 years in
Pinus
taeda
to more than 40 years in
Pinus longaeva
(Ewers and Schmid 1981;
Schoettle 1990). Longevity of leaves in
Pinus tabulaeformis
varies with latitude,
but at the extreme can be as short as 0.94 years (Xiao 2003). Needle longevity
of
Pinus contorta
in the Rocky Mountains of Colorado was 13.1 years at
3,200 m versus 9.5 years at 2,800 m (Schoettle 1990). A similar trend also was
observed in
Pinus contorta
in California: longevity at 15 m was 3.9 years, at
182 m was 4.2 years, and at 2,700 m was 7.9 years (Ewers and Schmid 1981).
In a warm temperate region, the leaf longevity of
Abies
was of the order of 6-8
years (Furuno et al. 1979). The half-life of leaves of
Abies mariesii
ranged from
3 to 9 years and up to as long as 13 years, varying among branches within the
canopy (Kohyama 1980). The mean leaf half-life is 7 years in
A. mariesii
and
only 4 years in
Abies veitchii
(Kimura 1963; Kimura et al. 1968). Eight species
of Asian, North American, and European
Picea
grown in northern Japan had leaf
longevities ranging from 5 to 11 years (Kayama et al. 2007). The leaf longevity
of
Picea mariana
was 5-8 years in Minnesota but 8-15 years in Alaska (Reich
et al. 1996). Niinemets and Lukjanova (2003) reported maximum needle lon-
gevities of 16 years in
Abies balsamea
, 12 in
Picea abies
, and 6 in
Pinus sylvestris
.
Gower et al. (1993) estimated leaf longevities of plantation-grown
P. abies
at
66 months,
Pinus resinosa
at 46 months, and
Larix decidua
at 6 months.
Larix
species are among the minority of conifer genera that are deciduous, unless their
needles are protected under snow cover (Gower and Richards 1990). An exten-
sive compilation of leaf longevity for coniferous trees augments these examples
(Wright et al. 2004).
Leaf Longevity of Angiosperms
Evergreen Broad-Leaved Woody Species
Leaf longevity of evergreen broad-leaved trees in temperate regions is usually
1-5 years. Nitta and Ohsawa (1997) provide a good example for 11 species
in laurel forests near the northern limit of evergeeen broad-leaved forests in
