Autumnal Resorption and Accretion of Trace Metals in Gallery Forest Trees

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Abstract
Autumnal resorption and accretion of copper (Cu), iron (Fe), zinc (Zn), and manganese (Mn) were measured in the foliage of five gallery forest tree species on the Konza Prairie Research Natural Area. Presenescence and postabscission leaves from five trees each of Quercus macrocarpa, Q. muehlenbergii, Fraxinus pennsylvanica, Celtis occidentalis, and Ulmus rubra were sampled. Three species resorbed 19, 25, and 26% respectively, of their presenescence foliar Zn, and one species resorbed 35% of its presenescence foliar Fe. This validates the prediction made by Whittaker et at. in 1979 that Zn and Fe are withdrawn from the scenescing foliage of at least some deciduous species. Net accretions of Cu (43, 44, 69%), Fe (36, 40%), and Mn (19.57%) occurred during the same period. The two oak species were responsible for most of the resorption, while the three non—oak species accounted for all of the significant accretion. Such well—defined differences in element conservation may influence interspecific competition by accentuating, or compensating for, species differences in element uptake ability and element use efficiency. Demand: availability ratios proved useful in predicting the likelihood that a given element would be conserved through resorption.