"Refurbishing" core growth of aspen grove...Possible?

Many here will be familiar with the typical appearance of an aspen grove:  Older, often dying trees in the middle with younger trees sprouting at the outer edge of the grove.  For a small grove in our front yard, there seems to be little, if any, new young trees growing up in the middle where the older trees have died, even though plenty of light is getting through at this point.  Is there some aspect of an aspen grove that inhibits new sapling production?  If they transplant easily, I have plenty of small saplings at the perimeter of the grove that I would prefer to move back to the middle. But I was wonder if this is futile due to some inhibitory aspect of the mature core of the grove??    Thanks for any insights into this issue....

Hello,
New aspen stems won't grow under old stems, even if there is enough sunlight, unless you cut the old stems. If you cant cut the old stems, new aspen is very easy to propagate from roots, which you can then replant in the middle of the grove given there is enough light. If there is almost any canopy cover at all the aspen will likely not take. If you have any more questions, just let me know.
Source: I am a forester who has done aspen management