Here’s some of the tree trunk collars that I made in 2011. They consist of Big W strings zip tied to plastic garden mesh.
Each year I simply wrap one around each tree trunk and zip tie the ends together. At the end of the season, they come off again with a couple of quick snips!
Note that the open end of the wiring harness cable faces down to minimise water ingress.
Here’s a taller one on a tree in the front garden.