Agriculture Reference
In-Depth Information
Temperate Deciduous Trees and Shrubs
The deciduous habit is characterized by the complete shedding of leaves during an
unfavorable period, usually in response to freezing or drought stress. In temperate
regions, deciduous (summergreen) trees that shed their leaves during winter often domi-
nate the forested landscape. The summergreen, deciduous habit is a superficial charac-
teristic of the tree that can mask the longevity of individual leaves during the
summergreen period. All deciduous trees are superficially similar in that in spring many
leaves appear on the tree and in fall leaves turn color and fall before winter. In reality,
leaves emerging in spring on some species survive until autumn, but in other species all
the leaves that emerged in spring have fallen by summer and been replaced by later
emerging leaves that persist until autumn. For example, Kikuzawa (1983) followed
leaf longevities in 41 tree species in the deciduous broad-leaved forests of Hokkaido,
northern Japan. The shortest longevity was 80 days in
Alnus hirsuta
and the longest
160 days in
Quercus crispula
and
Fagus crenata
. Species of
Alnus
are well known to
have short leaf longevity (Kikuzawa 1978, 1980, 1983; Kikuzawa et al. 1979; Kanda
1988, 1996; Tadaki et al. 1987). A comparable study of 16 deciduous tree species in the
Great Smoky Mountains of southeastern North America (Lopez et al. 2008) found leaf
longevities ranging from 116 days in
Aesculus flava
to 180 days in
Carya cordiformis
.
Some shrub species in the understory of deciduous forests have an unusual summer-
deciduous foliar habit. In
Daphne kamtschatica
, some leaves appear in early autumn
(September) and overwinter, new leaves also expand the next spring (April), and then
all the leaves are shed in June and July so that the plant is leafless in summer when the
tree canopy casts deep shade (Kikuzawa 1984; Lei and Koike 1998).
Tropical Trees and Shrubs
Even in aseasonal tropical forests, leaf longevity is not particularly long. For
example, we can infer from the data of Edwards and Grubb (1977) on litterfall and
leaf biomass that the leaf longevity of trees in a New Guinea forest averaged only
1.4 years. Hatta and Darnaedi (2005) surveyed leaf longevity of nearly 100 tropical
tree species in Bogor and Chibotas, Indonesia. Most trees had an evergreen habit
but about half had a leaf longevity less than than 1 year. Leaf longevities ranged
from only 2 months in
Inga edulis
and
Cryptocarya obliqua
to more than 30 months
in
Cinnamomum sintoc
. In the understory of the Costa Rican tropical forest some
trees have leaf longevities exceeding 2 years but others less (Bentley 1979).
Homolanthus caloneurus
is a pioneer tree in tropical lower montane forest with leaf
longevity of only 0.8 years (Miyazawa et al. 2006). In Venezuelan mangrove for-
ests, leaf half-lives were only 60 days in
Laguncularia racemosa
, 100 days in
Rhizophora mangle
, and 160 days in
Avicennia germinans
(Suarez 2003). Sixteen
species in the genus
Psychotria
, all understory shrubs in tropical forests in Panama,
have a remarkable range of leaf longevities, from 119 days in
P. emetica
to 870 days
in
P. limonensis
.
