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Abstract Detail


Developmental and Structural Section

Henderson, Lucas T. [1], Oldham, Alana [2], Sillett, Stephen [3], Tomescu, Alexandru MF [4].

Age-related anatomical variation in coast redwood (Sequoia sempervirens) leaves.

In contrast to the relatively short-lived leaves of deciduous trees, the leaves of many conifers are maintained for multiple years and thus provide opportunities to study age-related variations in anatomy. In coast redwood (Sequoia sempervirens), the world’s tallest plant, a high degree of leaf anatomical plasticity has been documented across the height gradient, yet age-related anatomical variation has not been previously investigated. In order to document such variation, we sampled shoots from the tops of trees >110m tall, avoiding effects related to light availability. Along the shoots, leaves were analyzed from each year of growth (first through fifth year) in order to compare anatomical characteristics at the cell and tissue levels. Ageing leaves acquire larger epidermal surface area and their cross-sectional circularity decreases, mostly as a result of an increase in width driven by stem thickening. The latter process is also very likely responsible for the observed increase in mesophyll porosity with age. The combination of these features may improve leaf gas exchange capabilities, by heightening photosynthetic rate at the expense of desiccation tolerance. However, the high water stress existing at extreme tree heights, coupled with low desiccation tolerance in older leaves, may outweigh the effects of improved gas exchange on photosynthesis. We observed significant variations in transfusion tissue cross-sectional area and transfusion tracheid circularity, but they did not exhibit consistent age-related patterns between trees. It is hoped that ongoing sampling efforts will reveal consistent patterns. A significant increase in cross-sectional area of vascular bundles with age is due to secondary growth in the vascular bundles. Our results indicate that estimates of whole-tree carbon uptake capabilities based on leaf characteristics should take into account the whole spectrum of variability in age-dependent leaf performance to improve the accuracy of physiological models.


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1 - Humboldt State University, Department of Biological Sciences, Arcata, CA, 95521, USA
2 - Humboldt State University, Biology, 1 Harpst St., office: 262 SciA, Arcata, CA, 95521, USA
3 - Humboldt State University, Forestry, 1 Harpst St., office: 262 SciA, Arcata, CA, 95521, USA
4 - Humboldt State University, Department of Biological Sciences, Arcata, California, 95521, USA

Keywords:
leaf anatomy
leaf age
Sequoia
mesophyll
transfusion tissue.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM
Number: PDS005
Abstract ID:263


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