Yes. There needs to be one clear tile between wild trees (like mahogany) or the secondary trees will stop growing at the point these little in-between trees of yours are. If a large tree beside them is cut down, they will continue growing.
So if you just want a near constant supply of hardwood, you could leave the small ones and one or two will grow quickly after the large tree has been cut down. If you want a forrest of big trees, you need to leave a space between them.
I usually plant a row of trees one space apart aong the edges of the trainyard, then plant more in between when their at the size of your small ones. Then, when I need wood, I chop the big ones and plant seeds in their place (the in-betweeners have reached the small size here by then) so I have a near constant supply of wood.
