The objective was to evaluate the decomposition of D. nigra and E. grandis leaves under laboratory conditions when incubated in soils from Atlantic Forest and from a 40-year-old eucalypt plantation for a year. The obtained values of pH in forest and eucalypt plantation soils were 5.61 and 4.47 and for aluminum 0.32 and 1.89mEqx100, respectively. A great number of microorganisms (total fungi, phosphate solubilising and cellulolytic organisms) were found in forest soil. Litterbag study revealed a higher mass loss of the leaves in forest soil in the first four months (c. 30%). In the eucalypt plantation soils loss was observed only after eight months (c. 40%). The initial contents of N and P were greater in D. nigra than in E. grandis leaves, although lignin and cellulose contents were similar. The C/N ratio was higher in E. grandis indicating that its degradation could be slower. Nonetheless, there were no significant differences in the decay rates (k) among the treatments. Phosphorus, lignina and cellulose were lost at the end of the experiment in all treatments. The results show the differences between decomposition of both species and the influence of forest and eucalypt plantation soils in the decomposition process.
Dalbergia; Eucalyptus; nutrient cycling; decomposition
