Agriculture Reference
In-Depth Information
Translocation
towards
lower soil P
concentration
Translocation
towards lower
precipitation
log (LMA)
Fig. 6.8 Scheme showing translocations of relationship between leaf longevity and leaf mass area
( LMA ) by changes in precipitation and soil nutrient conditions. (From Wright et al. 2002; drawn
after Westoby et al. 2002; redrawn by KK)
Deciding the Core Set of Cardinal Traits
These emerging patterns were a stimulus to many studies that led to a much larger
database against which the generality of the relationships could be tested. Peter
Reich, Ian Wright, Mark Westoby, and many others (Wright et al. 2004) pooled data
for more than 2,500 plant species and showed definitively that A max , LMA, foliar N ,
and leaf longevity were indeed integral parts of what they called the leaf economic
spectrum. Their data documented the range of values to be expected for the key traits
as well as the correlations among them: A max ranged from 5 to 660 nmol g −1 s −1 , foliar
N ranged from 0.2% to 6.4%, LMA ranged from 14 to 1,500 g m −2 , and leaf longevity
ranged from 0.9 to 288 months. They were able to compare values on a mass versus
area basis and found that the correlations among traits were strongest when expressed
on a mass basis. Shipley et al. (2006) reanalyzed the relationships among
four cardinal traits in the leaf economic spectrum that are highly intercorrelated
( A max , foliar N , LMA, and leaf longevity) and showed that a fifth trait in fact under-
pinned the relationships among these four foliar traits: leaf dry matter content
(LDMC). LDMC, the ratio of leaf dry weight to fresh weight, is an index of invest-
ments in structural versus fluid cell content. Niinemets et al. (2007a) reported a
strong correlation between LDMC and leaf longevity for 44 species in deciduous
forests in Estonia and showed that species with higher LDMC had cell walls more
resistant to deformation under turgor pressure. Compared to woody species, herba-
ceous species have lower LDMC, shorter leaf longevity, and greater A max (Ellsworth
et al. 2004; Wright et al. 2004; Shipley et al. 2006; Niinemets et al. 2007b).
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