Borer, Catherine , Sapp, Sarah Grace .
Phenology of foliar calcium accretion and partitioning in flowering dogwood (Cornus florida L.).
Flowering dogwood (Cornus florida L.) is an important understory tree species that is thought to enhance ecological calcium (Ca) cycling and soil Ca availability through high foliar Ca content and rapid leaf litter decomposition. Ca is an essential macronutrient in plants, important for stabilizing the structure of cell walls and plasma membranes. It is also a ubiquitous intracellular second messenger, helping plants to sense and physiologically respond to numerous internal and external environmental cues. Previous research demonstrated that analyses of total foliar Ca concentrations in red spruce trees (Picea rubens Sarg.) are not always consistent with a plant's true physiological Ca status because they can be dominated by a chemically sequestered form that is not readily available for cellular processes. In contrast, analyses of specific foliar partitions are more closely tied to Ca-dependent processes such as signal transduction.
To further develop our mechanistic understanding of the role of flowering dogwood trees in ecological Ca cycling, we investigated the phenological patterns of Ca partitioning and sequestration in the foliage of flowering dogwood. Grab samples of foliage were collected at 2-3 week intervals during an entire growing season, at a forested site in northwest Georgia. Foliage was rinsed, flash-frozen, freeze-dried, ground to a fine powder, and tested for three physiologically relevant pools of foliar Ca, using sequential acidic extractions. We found that flowering dogwood preferentially partitions Ca into the more labile and physiologically accessible pools of foliar Ca as Ca accumulates throughout the growing season, with minimal accumulation of sequestered Ca. This is in contrast to other species, such as red spruce, which sequesters Ca into a physiologically unavailable form once a sufficiency threshold has been reached, and white oak (Quercus alba L.), in which much of the foliar Ca is sequestered in a relatively unavailable form. This work helps elucidate a mechanism by which flowering dogwood can enhance Ca cycling in forested systems.
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1 - Berry College, Biology, P.O. Box 490430, Mount Berry, GA, 30149, USA
Presentation Type: Poster:Posters for Sections
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM