I have a rather young citrus tree (about 3 years, and been planted here for maybe half a year). I've noticed some weird light patches on the tree trunk, as shown in the image below. They seem to be located only towards the bottom part of the tree. I only noticed it yesterday. It feels wooden like the rest of the tree. It's not wet or anything.
The tree itself looks otherwise very healthy and seems to be passing through a growth spurt of some sort. The weather was very hot recently (36C/97F) and I've been watering it every day.
The only wildlife in the area are cats (I'm wondering whether it's a cat sharpening it's claws on it?)
What could it be?