Soils of Barro Colorado Island

Soils on Barro Colorado Island (BCI) are described using formal soil survey. More than 750 observations are grouped into six soil forms: shallow stony fine loams, dark fine loams, gleys, heavy clays, pale-swelling clays, and red-light clays. Only the red-light clays are restricted to a tropical climate and are the characteristic deep, highly weathered, nutrient-depleted, acidic soils of the tropics. The other soil forms are less weathered, which is consistent with ongoing regional uplift and erosion despite the tropical climate. Less weathering is associated with poor drainage (gleys, heavy clay soils), chemical element retention (pale-swelling clay soils), and soil erosion removing the most weathered surface material on the steeper surfaces (shallow stony fine loams). BCI has a broad range of soils with different degrees of development, drainage, nutrient fertility, and capacity to store soil organic matter. Soil survey and soil classification are ongoing processes and refinement with more work is expected.