scholarly journals Why does leaf nitrogen decline within tree canopies less rapidly than light? An explanation from optimization subject to a lower bound on leaf mass per area

2012 ◽  
Vol 32 (5) ◽  
pp. 520-534 ◽  
Author(s):  
R. C. Dewar ◽  
L. Tarvainen ◽  
K. Parker ◽  
G. Wallin ◽  
R. E. McMurtrie
Keyword(s):  
Lower Bound ◽  
Leaf Nitrogen ◽  
Leaf Mass Per Area ◽  
Leaf Mass ◽  
Tree Canopies

Vertical gradients and tree-to-tree variation in shoot morphology and foliar nitrogen in an old-growth Pinus strobus stand

2003 ◽  
Vol 33 (7) ◽  
pp. 1304-1314 ◽  
Author(s):  
Diane B Leal ◽  
Sean C Thomas
Keyword(s):  
Pinus Strobus ◽  
Leaf Nitrogen ◽  
Leaf Mass Per Area ◽  
Relative Role ◽  
Leaf Production ◽  
Forest Canopies ◽  
Leaf Mass ◽  
Needle Morphology ◽  
Foliar Morphology ◽  
Vertical Gradients

Acclimation to ambient light has been assumed to be the principal cause of vertical gradients in leaf nitrogen, foliar morphology, and related traits in forest canopies. We examined the relative role of crown exposure, damage, and reproduction as correlates of vertical gradients in shoot and needle morphology, anatomy, and chemistry in a ~120-year-old stand of Pinus strobus L. (eastern white pine) in central Ontario. Internodes at the top of trees were longer, wider, and produced more fascicles, but had lower fascicle survivorship than lower-canopy shoots. Needles on upper-canopy shoots also had higher allocation to resin ducts than mid- or lower-canopy needles, contained less nitrogen on a mass basis, and showed a higher leaf mass per area, C/N ratio, and chlorophyll a/b ratio. Tree-to-tree variation among the 26 trees measured traits was high, owing, in part, to differences in crown damage and reproductive status. Crown damage was associated with reduced leaf mass per area and other traits associated with shade acclimation, while high cone production was associated with reduced leaf nitrogen and chlorophyll in the upper canopy. Our results suggest that factors other than light acclimation play an important role in determining vertical gradients in foliar morphology, nitrogen, and leaf production in forest canopies.

scholarly journals Relationships between leaf life span, leaf mass per area, and leaf nitrogen cause different altitudinal changes in leaf δ13C between deciduous and evergreen species

Botany ◽  
2008 ◽  
Vol 86 (11) ◽  
pp. 1233-1241 ◽  
Author(s):  
K. Takahashi ◽  
Y. Miyajima
Keyword(s):  
Life Span ◽  
Carbon Balance ◽  
Stable Carbon Isotope ◽  
Leaf Nitrogen ◽  
Leaf Mass Per Area ◽  
Leaf Life Span ◽  
Deciduous Species ◽  
Evergreen Species ◽  
Leaf Mass ◽  
Assimilation Capacity

We examined the variability in stable carbon isotope ratio (δ13C) in leaves of two deciduous broad-leaved species and two evergreen conifer species along an altitudinal gradient in central Japan. The δ13C of the two deciduous species decreased with altitude, except near the upper distribution limit. The two evergreen species, however, showed no clear altitudinal trends for δ13C. The δ13C of the two deciduous species was positively correlated with leaf mass per area (LMA), indicating that the altitudinal variation in δ13C was controlled by LMA. Leaf nitrogen per mass (as a proxy of assimilation capacity, Nmass) was negatively correlated with LMA for the two deciduous species, while it was not correlated with LMA for the two evergreen species. Leaf life span of the two deciduous species decreased with altitude, whereas that of the two evergreen species increased. Thus, the two deciduous species had shorter-lived thinner leaves with higher Nmass at higher altitudes, and the two evergreen species had longer-lived leaves. These changes contribute to the positive carbon balance at higher altitudes. Therefore, the different changes in δ13C with altitude between the deciduous and evergreen species are ascribed to the different altitudinal changes in the leaf traits for carbon balance.

Sign in / Sign up

Export Citation Format

Share Document