Tropical Rain Forest Soils of La Selva

Tropical Rain Forest Soils of La Selva

Tropical rain forests across the globe are currently threatened by massive deforestation for logging, grazing, and cultivation (Otzen 1993). Such land-use practices alter temperature regimes (Fernandes and Sanford 1995) as well as ground, soil, and surface water, flora, fauna, and microorganisms (Otzen 1993). These changes may result in a loss of soil organic matter, a decrease in soil fertility (Garcia-Oliva et al. 1994, Tissen et al. 1994), severe soil erosion (Otzen 1993), and changes in soil structure and chemistry (Fernandes and Sanford 1995, Sollins et al. 1995, Montgagnini and Sancho 1994.)

The response of tropical rain forest soils to deforestation depends upon the specific properties of the soils as well as the type of use they are subject to. La Selva Biological Station, located in north-central Costa Rica and containing a mixture of pasture, second growth, and intact forest, provides an excellent opportunity to study the effects of deforestation on examples of three soil orders--Entisols, Inceptisols, and Ultisols. Although limited studies have been conducted on the impact of deforestation on soils in this area, a knowledge of their properties may help predict the nature of the changes that would occur due to deforestation. Such changes will determine whether or not rejuvenation of the rain forest is possible.

All soils at La Selva are derived from volcanic parent material. This material came primarily from eroded lava flows, although some material was carried in lahars. At higher elevations, soil parent material consists of lava weathered in place. Both alluvial and colluvial deposits cover the lower elevations, however, which include river terraces of various ages. Mos...

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