Axe, I have been away for a couple weeks with work and mending broken issues with employee troubles. Anyway, you bring up some points on slow growing trees make stronger wood.......correct. Evergreen's and oaks will grow in a vast selection of soil types and conditions. It isn't set in concrete that trees,plant, and shrubbery to be grown in groups such as in a forest; it is this setting that is favorable. Symbiotic relationships between like species and natural fungi that warrants off disease and increases vigor the natural way. Man spends billions a year force growing trees and plants to achieve the required color, shape and yield...........that is it. We force yield on a living things to maintain a contract such as in grasses. Back on topic,..............I have seen evergreen's and other such hardwood trees growing on a bluff, mesa or other areas with little to no silt, and all is just fine. But remember, there has to be those crucial nutrients present before life can be sustained. In the absence of these nutrients either through water, ground accumulation,etc. not even your trees would have survived on air and wind alone.