I've received some nuts from a friend here in Zone 3A. She says that she has to mow down sprouts every year, but are those squirrel-sown seedlings or are they actually "suckers" from the roots? Thanks for any info you can give me!
They will sprout from surface roots where a mower has damaged the bark, but seedlings are the more likely.
Seedlings from squirrel plantings seemed most logical to me, also. Is this a shallow-rooted tree? From descriptions of it being large and long-lived, I got the impression that the roots went deep and surface roots wouldn't be a problem.
There's no relationship between tree size or longevity, and root depth - all trees have most of their roots close to ground level (for collecting rain, and for aerated soil), and a few deeper 'sinker' roots (mainly for anchorage, and to a small extent for water uptake in droughts).