Methods of Facilitating Reforestation of Tropical Degraded Land with the Native Timber Tree, Terminalia amazonia

background

In tropical dry regions, like Costa Rica, it is critical to reforest degraded farms in order to reduce erosion and increase soil fertility. This paper explores the results of an 8-year long experiment in Southern Costa Rica that sought to identify ways to reforest such land economically.

Research Goals & Methods

The goal of the experiment was to compare the effect of fertilization to the effect of interplanting two species of legume trees (Inga edulis and Gliricidia sepium) on growth of a native tropical tree, Terminalia amazonia (Combretaceae). The authors did this by conducting a randomized block design in degraded cattle pastures. The blocks recieved various treatments and their effects on erosion and soil fertility were evaluated.

Conclusions & Takeaways

 After eight years, T. amazonia grew best in plots with treatments of interplanted Inga edulis and mixed (Inga edulis and Gliricidia sepium) trees. When fertilizer was added, the growth of the trees did not improve after the second year since plantation establishment. Moreover, the difference in soil erosion was correlated with tree growth. The authors conclude by asserting that that leguminous trees can act as nurse trees for the timber species T. amazonia, whereas fertilization alone may be an ineffective means of promoting tree growth.