Nice pictures, I like the tree one the most. The one i'd say could use a crop (im not an expert at all) is the winter scene with the water in the foreground. It looks really really dark, which kind of works with the trees one but the other one if you cut out the bottom open part of the stream where its not frozen, really changes it. I'm not sure, see what you think, i just dragged the picture onto the screen to the point that part was cut off.