LITTER DECOMPOSITION AND INORGANIC ELEMENT DYNAMICS IN A SECONDARY RAIN-FOREST AT ILE-IFE, NIGERIA

Leaf litter decomposition rates and variations in mineral elements con tent of decomposing litter of four tree species (Alstonia boonei, Funt umia elastica, Manihot glaziovii, Pycnanthus angolensis) were studied in a regrowth rainforest at Ile-Ife, Nigeria using the litter bag meth od. Decomposition rates of the species varied: M. glaziovii> A. boonei >F. elastica>P. angolensis. The loss in original weight of decomposing litter was linear in the early stages of decomposition but declined g radually at the later stages. No significant correlation was found bet ween decomposition constants and initial chemical constituents of leaf litter of these species. Monthly maximum and minimum temperatures and evaporation were significantly negatively correlated with monthly wei ght loss. The relationship between monthly rainfall and the rainfall:e vaporation ratio with monthly weight loss though positive, was not sig nificant. It took a minimum of six months for the litter to completely decompose. Copper, iron, manganese and zinc increased in concentratio n with decomposition. The concentration of calcium, magnesium, potassi um and sodium increased at the early stages of decomposition and subse quently decreased with decomposition. Nitrogen and phosphorus first de creased before increasing in concentration with decomposition. The ele ments showed different trends in their original mass remaining with de composition and in some cases elements exhibited different trends in d ifferent species.