Ronaldo Montoya wrote:Should i use this width value as separation between plants? for example if a tree has 100 feet , does that means that i should plant each tree with a separation of 100 feet at least ?
Not necessarily, though it's a rough guide. Trees in a forest setting may not ever reach these dimensions, because of their interactions with other trees, competing for light, water, ect. In any case though, this may not be applicable to you in the real world because they reach these sizes at maturity, which could be 100+years, not relevent to the typical time-scales of human beings. My own plantings include trees like pecan, walnut, and chestnut, all of which have very large mature canopies, though I've got them on 20' spacings because I expect them to be somewhat more managed then most. I don't expect these trees to become overcrowded in my lifetime. Still, I designed my plantings such that in the far future I could do selective thinning to remove individual trees without screwing up pollunation.
I do this to reach a balance between space and productivity. More young trees mean I'll have a usable crop with smaller trees while young, expecting that as the trees finally reach maturaty decades from now, thinning will not drasticly decrease production because of the increase productivity of larger singles.
I would take the age into account too. Some trees take a long time until they are mature and you can grow something else in between meanwhile. Some trees need shade when they are young, once again grow something else meanwhile. And trees must not grow to their full size this could be naturally or because you are pruning.
There is a lot of advice that tells to not plant too close, but this advice comes from England were there is next to no sun and it rains all the time. In a dry environment you want to preserve water by planting closely (that is what I am doing with everything), sometimes things become unmanageable, so what, take one tree out.
I would plant your whole site (well not what you want to grow with annuals) with nurse trees, like acacias which improves the soil. You only get a feeling for your place if you are there and work there. You can still make a plan. Before maybe you do what is necessary for the water.