These are really beautiful, especially for a beginner. Also, #3 is just hilarious.
Couple notes though:
1)Contrast could be better in them. They all have a washed out bluish tone that could be played with a bit. #2 is exempt from this statement
2)#3 is funny, but composition-wise, a little boring.
3) As for the issue of skinny, twisted things (#4), It's a hard shot to do, I usually try to get pretty close to the subject (The driftwood and barbed wire), and use a fairly open aperture so I can blur the hell out of the background, if shooting against a flat wall or something isn't an option. It also helps to shoot a light subject on a darker background, and vice versa. Here's an incredibly mediocre example of some swamp vines that I shot. Notice the background is a lot lighter, and totally out of focus, so it helps you see the vines despite the overall clutter of the forest.
Overall though, good work, keep practicing!