You did a great job! They really look like they're falling, and the changing blues in the background are great.
The first thing I thought of was "responding to gravity". Then, I was thinking about one of Bill Bryson's books, where he explains that the trees expend energy to make these beautiful leaves for us, and the trees really don't benefit from making the colors, so maybe "natural entertainment."
As you can see, I'm not very good at names!