The effect of soil nutrient availability on retranslocation of Ca, Mg and K from senescing sapwood in Atlantic white cedar

摘要

Nutrient resorption from senescing tissues increases plant nutrient use-efficiency, and may be an adaptation to nutrient limitation. In some tree species, retranslocation of nutrients from sapwood during heartwood formation is a comparable process.Ca, Mg and K concentrations were measured in Atlantic white cedar (Chamaecyparis thyoides) stemwood samples taken from two swamps in North Madison, Connecticut, and Pomona, New Jersey, USA and results were compared with soil mineral nutrient availabilityat each site. It was found that Ca, Mg and K concentrations were 60-700% higher in sapwood than in the immediately adjacent heartwood, indicating retranslocation of these nutrients from senescing sapwood. Sapwood nutrient concentrations were similar between the two sites. However, nutrient concentrations in the heartwood differed significantly between the sites, as did the relative degree of Ca and Mg retranslocation from senescing sapwood. These differences between sites were inversely related to significant differences in exchangeable Ca, Mg and K as well as Al concentrations in the soil. It was suggested that the degree of nutrient retranslocation from senescing sapwood may be influenced by soil nutrient availability.