Is not the species, is the old valuable individuals that are alive monuments. For example, ashes are frequent species, but 500 Yo ashes are very rare (The species can live this time but 99,99% are killed when they are less than 100 Yo). If you have a 500 Yo ash you may want to protect it. At this moment many temperate forests are like seeing a city when all inhabitants where 10 years old or less. This is not really OK. There is a problem here. People in cities are very afraid of trees and chomp it at the tiniest ludicrous excuses.

In any case Yuccas, like the Joshua Tree, are very easy to transplant and even easier to clone, so is just a question of throwing more engineering efforts at this problem because the trees can be moved and stand drough periods. Their biology allows to put a Joshua tree in an hangar and let it without any soil or water for a month. They just don't care. The main problem is to avoid breaking the branches. Easily fixable if you wrap the tree before

In the desert each tree counts also, as water container, so the more they have of a frequent species, the better for humans inhabiting the area.