Dynamics of litterfall production and decomposition in stands of Pinus elliottii Engelm. and Eucalyptus grandis W. Hill ex Maiden in the northeast of Corrientes

Abstract

This study evaluates litterfall production, forest floor mass and leaf-litter decomposition and growth in an 8-year-old Eucalyptus grandis stand and 467 trees*ha^-1 and in another 16-year-old Pinus elliottii stand with 533 trees*ha^-1, in the northeast of Corrientes, Argentina. In each stand, three permanent plots of 1000 m² were established. Four collectors of 1.0 m² and 12 litterbags of 20 cm² were randomly distributed in each plot. The measurements were made over 3 years. The relationship between environmental factors and leaf-litterfall was analyzed using the Pearson correlation coefficient (r). The E. grandis stand showed an annual increment (IMA) of 25.2 m³*ha^-1*year^-1, a mean annual litter production (PAL) of 10.1 Mg*ha^-1, an annual decomposition constant (K) of 0.7 and a half-life time (THL) of 1.0 years. The P. elliottii stand presented an IMA of 26.1 m³*ha^-1*year^-1, a PAL of 14.3 Mg*ha^-1, a K of 0.6 and a THL of 1.15 years. The highest material fall occurred during the summer for both species with maximum monthly mean values of 1.5 Mg*ha^-1 for E. grandis and 2.3 Mg*ha^-1 for P. elliottii. The leaves were the most representative component of the fallen material. The climatic variable that presented the highest correlation with material fall was the average monthly temperature. The dynamics observed in the stands, production, formation of mulch and its decomposition are characteristic of subtropical forests.