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Patterns of Leaf Tannin Variation in Chestnut Oak (Quercus prinus) and Black Oak (Quercus velutina) with Respect to Topography in a Southeastern Ohio Oak-Hickory Forest
Jennifer L. Reed and Brian C. McCarthy
Bulletin of the Torrey Botanical Club
Vol. 123, No. 3 (Jul. - Sep., 1996), pp. 243-248
Published by: Torrey Botanical Society
Stable URL: http://www.jstor.org/stable/2996800
Page Count: 6
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The carbon-nutrient hypothesis suggests that within a species, plants growing in high light and low nutrient conditions will commit greater resources to chemical defensive compounds compared to plants growing in low light and high nutrient environments. To test this hypothesis, we evaluated the patterns of leaf tannin chemistry in two species of oak (Quercus velutina L. and Q. prinus L.) utilizing protein precipitation methods. Leaves were sampled from mature, forest-grown, canopy trees found in a southeastern Ohio oak-hickory forest. To evaluate the effects of environment, we sampled along a natural gradient using trees from contrasting north- and south-facing slopes. To assess the patterns of variation in tannin abundance among populations, we sampled multiple trees from three different sites. Thus, data were analyzed for patterns of variation with respect to slope aspect and population. Quercus prinus trees growing on south-facing slopes had significantly greater amounts of leaf tannins than those on north-facing slopes but did not exhibit significant population differences in foliar tannin content. In contrast, Q. velutina trees on north- and south-facing slopes did not differ significantly in foliar tannin content but did exhibit significant population differences in foliar tannin content. Different species may have varying responses to the environmental stress associated with topography. Environment may have a considerable effect on leaf tannin content at the landscape scale. However, in some cases, populations may also contribute to variation and need to be considered when evaluating patterns of secondary plant metabolite distribution and/or plant-animal interactions.
Bulletin of the Torrey Botanical Club © 1996 Torrey Botanical Society