This caught my eye since I've worked and studied forestry, soil science and agriculture and I've lived in tropical countries. Along with the issues others brought up about protecting your trees, I would like to point out a few things that occur to me.
What do you know about the growth requirements of your desired species? Do they thrive in the same habitats, do they host disease or pests that can be transferred to your other trees?
If the land is fallow, why? What amendments will you need to make to the soil for your trees to grow? Can you achieve similar results with the proper mix of species?
Where would you get the required equipment, experience, fertilizer, seedlings/seeds, permits, and other things needed for your endeavor?
How will you earn money off the site in the mean time? Are there suitable fruit/nut trees or shrubs you can incorporate? Are there other agroforestry opportunities?
Will the market for your product exist in 20+ years?
If you have always wanted to be a farmer/forester who lives of the fruit of the land and sweat of your brow, then this could be the lifestyle for you. In that case, talk to some foresters, extension agents, and soil scientists familiar with the area you want to start your plantation. They should provide sound advice. Otherwise, realize you are making a job for yourself because it's unlikely that what you want to do can be a passive investment.