Agriculture Reference
In-Depth Information
Fig. 6.7
Relationships between leaf longevity and leaf traits: differences among biomes.
Relationships between leaf longevity and nitrogen concentration, nitrogen content, specific leaf
area (SLA), photosynthetic rate per leaf weight, and leaf area are similar among diverse biomes.
The slopes are similar, but intercepts sometimes differ. (From Reich et al. 1999)
annual temperature from −3°C to 26°C and in altitude from sea level to 3,500 m.
Despite the wide variations in environmental conditions among biomes, the
slopes of these relationships between leaf longevity and other foliar traits do not
differ significantly, but the intercepts do vary (Reich et al. 1997, 1999). The dif-
ference in intercept among biomes is the result of differences in LMA, which
becomes lower when water is in good supply. For example, comparing leaves of
similar leaf longevity, LMA is significantly lower in wet high-altitude regions of
Colorado than in arid New Mexico. Similarly, the intercept of the relationship
between leaf longevity and LMA in Australia is displaced to a lower value by
aridity, but the displacement can also involve a shift up or down along the existing
gradient (Fig.
6.8
). The presence of relationships at the global scale does not
necessarily mean the same relationships will be detected in regional data sets
(Santiago and Wright 2007).
