Leaves do not decay

Whenever I load up a new world and chop down any type of tree, the leaves do not decay.

What I expected to happen was...:
I was expecting the leaves to decay over time.

What actually happened was...:
The leaves stayed in place and never decayed.

Steps to Reproduce:
1. Create a new world
2. Chop down a tree
3. Observe the leaves and notice they don't decay.