The Demographics of Leaves

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Science  26 Mar 2004:
Vol. 303, Issue 5666, pp. 1949
DOI: 10.1126/science.303.5666.1949b

Leaf life-span (LLS) is a key functional trait of plants, yet co-occurring plant species often display a wide range of LLS. Documenting these patterns and relating them to variation in other traits and external ecological factors help to elucidate the range of ecological strategies exhibited by plants. Two studies suggest that LLS has a close association with factors other than water availability.

Ackerly measured LLS in 20 co-occurring shrub species in the Californian chaparral—a habitat with a pronounced dry season—and assessed its relation to maximum water deficit and a suite of physiological, functional, and morphological traits. LLS ranged from 2 to 4.5 months in deciduous species and from 7.2 to 22.4 months in evergreens. It was not significantly correlated with water deficit, and shorter LLS was generally associated with an ability to assimilate carbon rapidly and a shorter plant stature. Reich et al. censused the timing of birth and death of 40,000 leaves of 23 tree species in the northern Amazonia rain forest—where the dry season is short and unpronounced—recording a range of LLS from 0.7 to 4.2 years. In this case, LLS was related to environmental factors such as light availability, disturbance regime, and soil fertility, but bore little relation to seasonal patterns of rainfall. — AMS

Ecol.Monogr. 74, 25; 3 (2004).

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