Leaf litter decomposition and mulch performance from mixed and monospecific plantations of native tree species in Costa Rica

An experiment with native trees was established in 1991 on degraded pasture in the Atlantic lowlands of Costa Rica to examine the influence of mixed and monospecific plantation designs on tree growth and nutrient cycling. As part of this study, leaf litter decomposition rates and mulch performance were compared among four native tree species, Callophylum brasiliense Cambess, Jacaranda copaia (Aubl.) D. Don, Vochysia guatemalensis J.D, Smith, and Strypnodendron microstachyum Poepp. et Endl. Leaf litter of V. guatemalensis, J. copaia and the mixed plantation decomposed the fastest, with less than 16% of the initial weight remaining at 12 months. C. brasiliense had the slowest decomposition rate with 23% of the leaf litter remaining at 12 months. V. guatemalensis had the greatest amount of annual leaf litter fall and accumulation, J. copaia showed high levels of annual litter fall but fluctuating forest-floor litter accumulation, and the mixture showed intermediate patterns of annual leaf litter fall and accumulation. All mulch treatments improved maize seedling performance in comparison with unmulched controls. S. microstachyum mulch was found to have the most beneficial effect on initial maize seedling height growth and N uptake. Recommendations are drawn from the results to suggest potential uses of these species in forestry and agroforestry systems.