In my area some of these go bald in the middle also. As do some specimens of various other Cypress Family conifers, including the native Thuja plicata; in the latter case in particular it is thought that a sparse habit is the result of site conditions being less than optimal.

I looked through some of the older postings but didn't see any about this

==>> really.. no post mentioned that interior browning and needle loss is ENTIRELY normal ... crikey i know i typed that about 1000 times over the years ... lol.. you gotta love.. unsearchable titles ...

perhaps part of it.. was that you think its somehow associated with your species ... it isnt ....

go to any forest .. conifer.. or deciduous.. look up.. ALL TREES ARE NUDEY INSIDE ..
as the canopy expands.. there isnt enough sunlight inside.. for the plant.. to waste energy on producing leaves in the dark ... and if they do.. they abort regardless ...

soooo.. on your babe... on a tree that can grow for 100 years [except for what it is.. lol]. ... yours is finally maturing enough.. to shade out the interior ...

ALL NORMAL ...

start worrying.. when the exterior is not thriving ...

ken

ps: at 20 years.. yours is barely entering the teens years.. in tree time ...

Hmm i didn't write that I had read all the posts --Some --

BTW I don't poke my nose in other's business and don't usually poke my nose in the middle of trees

Thanks for the assurance!