ASPECTS OF RAINFOREST REGENERATION

Abstract

SUMMARY Measurements in two sub‐tropical rainforests demonstrated that (i) in one rainforest succession, total soil phenols varied dramatically throughout the study year with soils from the ‘climax’ rainforest exhibiting highest phenol levels, the nature of these phenolic compounds was not investigated; (ii) in the other rainforest succession, the 55‐year‐old regrowth exhibited highest total phenols, but the level of condensed tannins increased throughout the succession. The highest level of nitrification was observed in soils containing highest total phenols but the addition of ferulic acid decreased nitrification. Studies on Argyrodendron trifoliolatum demonstrated that addition of the phenol, caffeic acid, to nutrient media enhanced leaf concentrations of Zn, Mn and P. Increasing light intensities, however, decreased foliar concentrations of Fe, Zn, Mn and P but had no effect on Ca or N. Plants raised on ammonium −N exhibited higher levels of Fe, Zn, Mn and P than those raised on nitrate–N. Glasshouse trials showed that at low light intensities omission of N, P and N + P did not dramatically enhance leaf phenol production. Almost invariably, an increase in light intensity increased leaf phenols but only one of the four species examined ( Syzygium floribundum ) exhibited marked responses to nutrient deficiencies at high light intensities, with the omission of nitrogen leading to highest leaf phenols.