I increased the contrast a tiny bit.
I adjusted the levels just a tiny bit.
I got rid of a small distracting part near the bottom on the left of the trunk.
I applied unsharp mask once.
I dodged the shadows a little to bring out a bit more detail.
Statistics
Place: 85 out of 251 Avg (all users): 5.7000 Avg (commenters): 6.7500 Avg (participants): 5.6517 Avg (non-participants): 5.7426 Views since voting: 864 Views during voting: 283 Votes: 190 Comments: 10 Favorites: 0
The leaves come off as a bit drab. Did they get affected by the post processing? There also seems to be a bit of a halo along the right most limb at the vrey top of the picture.
Other than that, it looks really good. Though I suppose there might have been a voter or two who noticed the limbs from another tree coming in from the left. That's about the only way I can see you didn't score a little higher.
Gum tree bark is especially smooth and your photo captures that well. Eucalyptus grows the world over. When it was planted in the colder parts of Russia, the tree adapted to become deciduous.