Leaf Litter Decomposition and Mulch Performance from Mixed and Monospecific Plantations of Native Tree Species in Costa Rica

background

This research looks at leaf litter decomposition rates and mulch performance of four native tree species in mixed and monospecific plantations at the La Selva Biological Station in Costa Rica. The four species considered were Callophylum brasiliense, Jacaranda copaia, Vochysia guatemalensis, and Strypnodendron microstachyum. The faster the decomposition, the faster the nutrient transfer from the trees into the soils for uptake by other trees or by crops when the leaves are used as mulch.

Research Goals & Methods

Fresh leaves were collected from perimeter trees, oven-dried,  and placed in 20 cm x 20 cm litter bags made of fiberglass mesh. 540 bags were weighed and the percentage of the original weight was calculated.  

Conclusions & Takeaways

The mixture of all species and the single-species plots of V. guatemalensis had the fastest rate of decomposition. Stands of Callophylum brasiliense had the slowest decomposition, which could be due to a lack of canopy closure. S. microstachyum stands had the highest deposition of nitrogen following decomposition. Additionally, the authors tested the effect of mulch on maize seedling height, growth, and N uptake. S. microstachyum mulch had the most beneficial effect; however, all mulch treatments (including mixed leaves) had a positive effect on seedling performance compared with unmulched controls. The authors recommend that mixtures or V. guatemalensis stands may be the most useful for forestry because of their closed canopy and litter decompositions. For agroforestry systems, they recommend S. microstachyum and J. copaia because of their benefits as mulch and the light offered by the more open canopy.