If you have ever taken photographs in a forest, you know that it can be challenging to find a good composition in a cluttered environment. One of the techniques we use for cluttered scenes like these is to isolate elements by size. This helps them stand out against a cluttered background, and clearly identifies those elements as “more important” than smaller elements within the frame.
Take a look at the above photograph of Ponytail Falls in Columbia River Gorge (Oregon). I composed the photograph so that the waterfall and the foreground trees appear to be larger than the rest of the elements. In doing so, I was able focus the attention of the viewer on these three elements.
Here is another example from the Hoh Rain Forest in Olympic National Park (Washington). Here, I have used size to isolate the old tree and the two trees leaning towards it. Because of their size, they stand out in the composition, and the viewers attention is focused on them.