I've had my K5 for all of three months, so I'm still on the steep side of the learning curve myself. Depending on what kind of program you're using or whether these are RAW or JPEG, I suspect you could play around with the "Curves" adjustment to make the light bark of the downed tree "pop" against the dark vegetation on the opposite bank. (Or better yet, post the pic in the "Critique" section and get some advice for somebody who knows a bit more what they're doing...
)
At any rate, it's a beautiful part of the world (I'm here in Knoxville)--I'm guessing you were in the Cades Cove area, but I'm having a hard time placing the waterfall.