The only thing I "disagree" with (not so much "disagreeing" as just having a different interpretation) is that the first shot doesn't have a strong vertical line from the trees. In fact, it doesn't have strong directional lines at all other than the horizontal of the shoreline. It looks too busy because there are too many conflicting straight lines with no clear pattern. None of them really direct the eye anywhere, so it ends up feeling unbalanced and unfocused (in terms of composition, not lens focus.) This is why it may be better in color, which doesn't rely so heavily on form and lines.
The second one is very strong in black and white because of that clear upward sweep of the trees, and the two larger trees to balance things. Your pose also mirrors the upward lines. The eye has clear patterns to follow and the composition becomes about the form as much as the subject.
The third one also has clear lines, created by the subject but also by light and texture. The curve of her left shoulder mirrors the curve of the tree in the background on the left of the frame. The texture of her hair mirrors the blurred bushes in the background on the right of the frame. The light pattern also highlights these patterns.
The second and third shots are the ones that I think benefit from black and white because you have strong compositions that also have added elements of strong shapes and forms - elements that may have been less noticeable in color - that contribute to the overall image.