Biophysical Interactions Between Timber Trees and Arabica Coffee in Suboptimal Conditions of Central America

Especially in the less favorable areas (altitude < 800 m and mean air temperature > 25 °C) that predominate in Central America, there is a renewed interest in managing Arabica coffee (Coffea arabica L.) under shade after three decades of promoting intensively managed coffee systems planted in full sun with highly productive dwarf cultivars. The presence of shade trees, especially leguminous species, improves soil fertility (organic matter content and nutrient cycling) and enhances coffee plantation sustainability (Beer et al., 1998; Soto-Pinto et al., 2000). In suboptimal coffee producing areas with low altitude, shade trees greatly reduce excessive solar irradiance and buffer large diurnal variations in air temperature and humidity that are detrimental to coffee physiology (Gutiérrez et al., 1994; Siles and Vaast, 2002). In mountainous areas, associated trees decrease soil erosion and nutrient leaching, especially nitrogen (Babbar and Zak, 1995). Therefore, shade trees play an important role in the Central American region due to the valuable impact of coffee agroforestry (AF) systems on the environment and natural resources such as preservation of biodiversity, soil conservation, water quality, buffering effect around protected areas, reduced pressure on forests, and carbon sequestration (Somarriba et al., 2004). In this region with a long-lasting reputation for commercializing quality coffee, shade can also contribute to the production of high-quality coffee as demonstrated in Guatemala (Guyot et al., 1996), Costa Rica (Muschler, 2001), and Honduras (Decazy et al., 2003). Nonetheless, trees associated to coffee are mainly legume species (Erythrina spp. and Inga spp.) with no timber values that are pruned periodically to avoid large decreases in coffee production due to competition for light, nutrients and water during the dry period (Beer et al., 1998). Indeed, timber trees are less common in coffee AF systems of Central America despite the fact that timber could greatly help farmers to diversify their income.