AGE-RELATED CHANGES IN NUTRIENT RESORPTION PATTERNS AND TANNIN CONCENTRATION OF CASUARINA EQUISETIFOLIA PLANTATIONS

YE GF, ZHANG SJ, ZHANG LH, LIN YM, WEI SD, LIAO MM & LIN GH. 2012. Age-related changes in nutrient resorption patterns and tannin concentration of Casuarina equisetifolia plantations. Tannin levels and nutrient resorption of Casuarina equisetifolia at different developmental phases (juvenile, mature and senescent phases) were examined to evaluate possible nutrient conservation strategies under nutrient limitation. Results showed that C. equisetifolia branchlets contained relatively higher contents of total phenolics, extractable condensed tannin, total condensed tannin contents and protein precipitation capacity in juvenile stands compared with those in mature and senescent stands. Nitrogen (N) concentrations in mature branchlets increased with stand development, while phosphorus (P) concentrations showed a decreasing trend. Nitrogen:phosphorus ratios in mature branchlets were above 20 and increased with stand development. Phosphorus resorption efficiencies were significantly higher than N resorption efficiencies, with the highest in mature stands. Tannin level, nutrient concentration and resorption were affected by stand age. Our results indicated that at intraspecific level, C. equisetifolia could adjust its nutrient conservation with stand development.