From shade- to sun-grown perennial crops in Sulawesi, Indonesia: implications for biodiversity conservation and soil fertility

Traditional, complex forest farming systems are increasingly converted to sun-grown monocultures throughout the tropics. Biophysical, soil and biodiversity effects associated with sun- vs. shade-grown coffee and cacao were investigated in a case study in Sulawesi, Indonesia. Canopy height, tree, epiphyte, liana and bird species diversity, vegetation structural complexity, percent ground cover by leaf litter, and soil calcium, nitrate nitrogen and organic matter levels in the O horizons were all significantly greater in shaded than in sun- grown farms. In contrast, photosynthetic active radiation (PAR), air and soil temperatures, weed diversity and percent ground cover by weeds were significantly greater in sun compared to shade farms. At the landscape level, conversion of shade-grown crops to sun conditions isolates protected areas and remnant primary forest fragments. Local cultivators are cognizant of the agronomic and socioeconomic risks associated with sun- grown perennial monocultures and some are increasing the density and diversity of fruit tree cultivation in an effort to provide shade and organic matter, and increase and diversify crop yields. The maintenance of traditional, complex forest farming systems, particularly shade-grown perennial crops, warrants greater attention in agricultural development and biodiversity conservation efforts.