La Selva Biological Station is located in Central America, in the humid lowland slopes of the Atlantic side of Costa Rica, at 10°26' N latitude and 84°01' W longitude).

The town nearest to La Selva is Puerto Viejo de Sarapíqui. The capitol of Costa Rica, San José, is 1.5 hours to the south. La Selva has a mean annual rainfall of ~4000 mm and mean temperature is 26 ° C (Sanford et al. 1994). The native vegetation is tropical broad-leaved evergreen rainforest with a notable abundance of understory palms.

The study plots, known as the Peje Plots, are situated 5.3 km from the laboratory clearing at La Selva, via a paved trail. Access to the plots is by bicycle , as motorized vehicles are not allowed at La Selva. Topography of the study plots is hilly, with elevations ranging from 44 to 89 m.

Soils in the proposed study sites are residual soils derived from basalt, with no evidence of volcanic ash deposition (Fisher 1995). They were classified as Typic Tropohumults in the Matabuey consociation by Sollins et al. (1994) and as Mixed Haplic Haploperox by Kleber et al. (2007).  These soils are typical of young but highly weathered soils derived from igneous rocks in both New and Old World tropics (Fisher 1995).

Satelite imagery of La Selva, Feb. 2003, with ECOS plots outlined in red. The boundary of La Selva is in green.

Satellite imagery (close-up) of ECOS plots