Attempting Restoration of Wet Tropical Forests in Costa Rica

Background

This article describes a reforestation effort of the Tropical Forestry Initiative using mixed stands of native species to recover abandoned pastureland in the tropical wet forest of Costa Rica.

Research Goals & Methods

Over a period of 5 years, an area of 5 hectares of abandoned pasture was reforested and monitored in stages. Initially, the seeds of 7 native hardwoods species were collected, raised in a nursery, and then planted as saplings. Approximately 5000 saplings were planted in the first year, spaced at 3m x 3m in open pastureland and at 4m x 4 m in areas of partial scrub growth. In the following five years, 3000 to 5000 saplings were planted per year and the plantings were expanded to include 41 native species. Transects totaling 750 meters were used to measure the height and dbh of those trees planted in the first year. The recovery of species complexity was assessed in seven 20m x 20m plots, based on the identification, mapping, and measurement of all planted and colonizing seedlings, as well as the canopy coverage.

Conclusions & Takeaways

Of the 7 species which were planted originally, Schizolobium parahybum and Terminalia amazonia had the fastest growth rates, while Pithecelobium arboreum and Platymiscium pinnatum had the slowest growth rates. With regard to species complexity, the quadrats showed that 46% of the ground cover had been occupied by volunteer scrub and tree species, especially by 10 early-succession tree species. Except for 2 species, Enterolobium cyclocarpumand Cedrela odorata, all planted species showed over a 90% survival rate. The authors suggest that the results of this experiment indicate good prospects for mixed-stand, native species reforestation as an alternative to monoculture plantations.