Mixed Plantations of Native Trees on Abandoned Pastures: Restoring Productivity, Ecosystem Properties, and Services on a Humid Tropical Site

Abstract

Twelve native tree species grown in mixed and pure plantations on degraded pasturelands at La Selva Biological Station in the Caribbean Lowlands of Costa Rica were evaluated at 15–16 years of age. Mixed plantations performed considerably better than pure plantations. The best performing species under both conditions were Vochysia guatemalensis, Virola koschnyi, Jacaranda copaia, Terminalia amazonia, and Hieronyma alchorneoides. Mixed plantations were among the most productive in terms of volume and carbon sequestered, performing as well as pure plots of fast-growing species. Thinning and pruning improved growth, quality, and stability. At 2–4 years of age, three species suffered less pest damage in mixed than pure stands, while other species suffered no damage or similar damage under both conditions. At 6–8 years, four species suffered total mortality in pure plots and limited survival in mixed plots due to pest damage. Mixed plantations sometimes improved soil conditions such as higher organic matter, and had intermediate values for the soil nutrients examined. Both pure and mixed plantations facilitated tree regeneration by attracting seed-dispersing birds and bats. Income from thinnings and final timber harvest seem to strongly exceed establishment and management costs, providing an economic incentive for similar plantations. These systems are productive options for restoring degraded agriculture or pasturelands of the region.