干旱区生态环境知识资源中心

1. Relationships of leaf traits with rainfall at the place of origin of seed (R,,,) are a function of acclimation and adaptation. To disentangle these effects we studied 29 species of 16-year-old Eucalyptus at a productive and an unproductive common garden (mean annual increments of above-ground stem volume = 21 +/- 11 and 8 +/- 5 m(3) ha(-1) years(-1), respectively). We tested three hypotheses: (i) leaf traits vary between sites, but relationships among them do not; (ii) relationships of leaf traits with R-PO do not vary between sites; and (iii) ecotypes originating from low-rainfall areas allocate a small fraction of nitrogen to thylakoid proteins and Rubisco, and have small SLA, small and narrow leaves, and large water-use efficiency (WUE).

2. Eleven leaf traits (leaf area, leaf thickness, leaf width/length, specific leaf area, fresh weight/dry weight, N, chlorophyll alb, carotenoids/chlorophyll, thylakoid N%, Rubisco N%, WUE derived from C-13 content) were measured in 1-year-old sun leaves.

3. Site had a large effect on not only the absolute values of leaf traits, but also relationships between pairs of traits. There were 20 significant correlations between pairs of traits. Three of the correlations had different slopes between sites, while a further nine had different intercepts. Hence the majority of significant correlations were not independent of site.

4. Leaf area and leaf width/length were the only traits related to R-PO. There was no evidence that N allocation to Rubisco or thylakoid proteins was related to R-PO, or that WUE was greater in ecotypes from dry areas.

5. For Eucalyptus, and perhaps other genera, physiological leaf traits may play a minor role in adaptation to water availability. There is large phenotypic plasticity in many leaf traits affecting not only the absolute values of traits, but also relationships among them.