Lee, I want to respond to your post by first saying there isn't a composition "rule" for photography/painting I haven't used, and haven't broken, as needed. That being said, composition rules developed because they worked and using them, such as the "Rule of Thirds" can be extremely helpful in creating a very good photograph, yet more often than many less experienced photographers think is the case, it makes great sense to ignore or break the rules of composition.
Composition is much more than aligning objects in the scene with a grid. To me, composition is much, much more about flow and balance, how the eye moves through the photograph to observe it.
There are many different rules, or methods of composition; diagonal line, converging lines, geometric shapes, leading lines, framing, symmetry and patterns, viewpoint, etc. All can be used for landscapes, and for that matter, all can be ignored. Understanding these "Rules" is important. To paraphrase a phrase from an old Kenny Rogers song ("You've got to know when to hold them, and know when to fold them.") you've got to know when to use them, and know when to ignore them. Before you can ignore them, you need to understand them.
You can use both symmetrical, "formal," and asymmetrical balance in your photo, for example. In the photo above, it's pretty much a symmetrical balance. Symmetrical balance generally produces images which are restful, calming, and visually stable. In this case, for me, the balance doesn't work.
In your photograph, along with symmetry, you're using a major foreground object. Foreground objects are great for showing the depth of a landscape. With something in the foreground, the viewer of landscapes has a way to distinguish distances and sizes, making the photograph look less flat and further from the camera.
In this case, the foreground object is a silhouette. Due to it's color in relation to the remainder of the photograph, and its strong contrast to the background colors, it predominates. It's size adds to its dominance in the photo. In fact, to me, it predominates so much I had a hard time getting past it to the fabulous color background. There is so much of the silhouette it doesn't pull you into the photo, at least for me. It stops me cold. It stops me from exploring the photo further. It's like getting stuck in a dense thicket, and having to turn around because you can't get through. Even if you had used the rule of thirds vertically, which is the important axis due to the use of portrait orientation, for the photograph either having more sky, or more water I doubt would help the photograph improve due to the strength of the foreground tree.
A strong foreground object, but one less predominant, a smaller and less branched tree, for example, would have been great to pull your eyes into the photo and give it depth, but the size of the tree in the photo, obscuring the background for me, did little to create depth for me. The tree also blocked the background instead of framing it, if you were going for that.
I don't think using the Rule of Thirds would have been helpful, but an asymmetrical balance which pushed much of the tree off to the side opening up much of the photo so you can enjoy the photo would have made a better composition for the view.