TNT doesnt blow up wood

This is the summary of the bug I am having.

*What I expected to happen was the TNT to blow up my forest

Describe what you thought shoul
*What actually happened was i was left with a huge crater and floating wood.
Describe what happened i killed heaps of creepers and made 20TNT i blew up my forest with it i looked at the after math and it was at least 15 trees floating in mid air

Steps to Reproduce:
1. Place a door down in creative mode
2. Break the bottom half of the door
3. ...