Can agricultural policies affect the land use and planting patterns of farmers? Can they be used to encourage the planting of more environment-friendly crops? These have been the questions posed by Dr. Gerald Shively during a recent PIDS Pulong Saliksikan. Utilizing a dynamic model of portfolio choice in 115 Palawan farms, the author examines the mango-planting decisions among low-income farmers and how such decisions influence the health of the ecosystem.