The princess mother played an active role in the Doi Tung Development Project, beginning with nursing tree saplings herself and replanting forests. Surrounding the palace are experimental plots where temperate crops are tested, such as Arabica coffee beans from Brazil and Costa Rica, macadamia, and chestnuts. Mulberry trees, the fibre of which is used to make "sa" paper, is another of the money-making crops they plant, nurture, and process. New plant cultivation technologies are continually tested for the cultivation of asparagus, bananas, orchids, and strawberries. After successful trials, villagers are trained in the techniques to follow, the improvements designed to provide them with increased income.