Now I wanted to know, whether the trunk is continuous or dissolving.

Sorry, I don't understand you. The trunk of any tree is permanent. It grows by
adding another layer of wood every year. The bark however, is usually not
permanent. The tree sheds it a little at a time. Is this what you meant?
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)