This injury is at an interesting height. Perhaps a cat used the tree for a scratch pad or a Raccoon standing on his back feet ate some cambium during the winter?
This looks as if when the ring of CMU of this little wall was made that some big equipment bonked into your tree? 3 years ago? Or so?
I would strip all of that bark mulch out of that ring. Dump it somewhere else to decompose. That moisture at the bottom of the trunk is caused by this non decomposed mulch. This will GIRDLE your tree. Bacteria are encouraged to begin decomposing the dead bark and live cambium. Using the cambium for energy. This is the same thing as taking a sharp knife to girdle the thin cambium lying just below the bark. Kills the tree slowly but surely.
My eyes aren't that great but someone mentioned weed fabric? Is that black plastic beneath the bark chips? Your tree has done its best to work around the injury. Leave that completely alone. Get rid of the stuff on top of the roots and the trunk.
There is a very specific line between trunk and roots. Roots are beneath the soil and trunk is not compromised by soil, mulch, rocks at all. Leave the wall. That is not the problem.
How is the health of the tree? Send a picture of the entire tree so we are able to see the extent of the damage. Have you ever fertilized?
Just an aside, your lawn is mowed way too short! Check out our stuff on lawn care! Raise your deck to 3 or 3 1/2 inches. Trust me, humongous difference. Golf courses actually use weed grasses with shallow roots so that they thrive being cut as short as astro turf. Our lawn grasses have huge root systems and need 3" minimum of top growth to feed those roots, shade out weed seeds in the soil bed, out compete weeds because there is enough photosynthetic growth to make enough 'food' for the plant to be vigorous.
Water only when you see yourfootprints stay down on your lawn. Never before. Fertilizer 4X/ year. Aerate, pulling cores out of the soil bed, once per year. Sharp sharp blades, bag clippings. Test pH before adding any lime. Nothing else should ever be added to a lawn. Check out other lawn information. On this site, not at Lowes or Home Depot! Grins!
The injury will be fine, nothing you can do, now. Give it some air, pull mulch and plastic off the base of the tree completely. Send a picture of the entire tree so we can see the extent of the damage?
Those weed fabrics were designed for under layment of gravels, not weed suppression. Doesn't do a thing for weed control. They sell this stuff under weed fabric labels knowing most people won't know any better.
Location of damage
Other areas of bark are also flacky
Base of tree
Top of tree
Fresh growh (lighter green leaves)
