Head, Lisha , Mooney, Amber , Borer, Catherine H. .
Cornus florida’s sequestration of labile calcium and its role in calcium cycling.
Flowering dogwoods (Cornus florida) are admired for being an aesthetic part of our forest understory, but they also play important ecological roles. Dogwood trees may take up substantial amounts of calcium and make it readily available for nearby plants through decomposition of their foliage, making dogwoods an important factor in forest calcium cycling. However, the partitioning of foliar calcium in dogwoods and other species is not completely understood. Calcium is an essential macronutrient used in cellular messaging, plasma membrane stability, and cell wall structure. In plants, only certain portions of foliar calcium are available for physiological processes because much of the calcium can be immobilized as crystalline calcium oxalate. We compared the uptake and sequestration of calcium in the foliage of two common southeastern forest species: flowering dogwood and white oak (Quercus alba). Foliage samples were collected at sites on the large Berry College campus that were predicted to be high in soil available Ca and sites predicted to be low in soil available Ca, based on the underlying bedrock type. Soil samples were collected from 4 different depths at each field site. Foliage samples were dried, ground into a fine powder, and three different physiologically relevant pools of foliar calcium were separated using sequential acidic extractions. Soil samples were dried, sieved, and calcium was extracted using a Modified Morgan procedure. Calcium in each extraction solution was assessed using a colorimetric method. Preliminary data from the mineral soil samples are consistent with our hypothesized high and low calcium sites. We found that the foliage of flowering dogwood has a significantly higher proportion of labile and physiologically relevant calcium than that of oaks. However, foliage data show no significant difference in the Ca partitioning in oak foliage between sites with and sites without flowering dogwoods. This work underscores the importance of flowering dogwood trees in calcium cycling due to their preferential partitioning of calcium into the more easily mobilized forms.
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1 - Berry College, Biology, 2277 Martha Berry Hwy, P.O. Box 430, Mount Berry, GA, 30149-0430 , USA
2 - Berry College, Biology, P.O. Box 490430, Mount Berry, GA, 30149, USA
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM