LTREB: Sustainability of Soil Fertility in Model Tropical Ecosystems

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9975235HartshornMaintenance of soil fertility is a major challenge to forest restoration and sustainable development in the humid tropics, where organic matter breaks down quickly, weathering of mineral matter is fast, and high rainfall leaches nutrients essential for plant growth. Among the many factors that control soil fertility, two are of great importance in both natural and managed ecosystems, the number of plant life forms and the frequency with which the plant community is harvested or disturbed. Replicated plantations comprising three fast-growing tropical tree species established in 1991 at La Selva Biological Station in Costa Rica are used to study the controls that these two factors exert on soil fertility. In some plantations, the trees are grown in monocultures, which are harvested and replanted at three different intervals. Other plantations contain the trees plus plants of two other life forms, a palm and a banana-like herb. Research for the next five years on this LTREB project will address five broad objectives: (1) determine nutrient retention, loss, and recovery following stand turnover, (2) attempt soil recuperation through nutrient replacement, (3) quantify processes that account for changes in soil fertility as a function of changes in community structure, (4) track the sequential changes in interspecific interactions and their impact on soil fertility, and (5) identify mechanisms involved in temporal changes in complementary resources use. The project will provide valuable insight on tropical forest ecology and management. In addition, the project will continue to train undergraduates and graduate students, and serve as a laboratory for courses offered by the Organization of Tropical Studies, local and international universities, and informal science visits.