Edit: Apparently, together with climate data you can determine the year the tree was cut down hundreds of years after the fact [0].
If you plant a tree that lasts for 10,000 years (is there such?), I wonder if you can use its height or the shadow it casts (trunk thickness) to measure time.
Of course, someone would just come and kill it. Unless you can make it undesirable to get close to it.. for example fill it with thousands of snakes and spiders.
As far as we know, there are a few clonal plant colonies that have survived longer than 10K years. No individual plants have quite made it to 10K, but some have made it past 2-3K years.
Yes, there are colonies of quaking aspen trees that are estimated to be 80,000 years old: https://en.wikipedia.org/wiki/Pando_(tree)
(except human activity is killing it today)
Because future humans may lose the ability to see the count in the genome .. or just forget it exists and never notice it.