Are the meadows in the Alps caused by cows and sheep? Could be. I thought of that too. There is no doubt that they contribute to it (we saw plenty of both everywhere). But it is also a "which came first" thing. The cows and sheep were sent to the high lands because there were meadows up there. I think the word "alps" comes from the meadow, not the mountains. It is possible that the meadows might have started small and then grew with livestock, or maybe they were big to begin with (we did see plenty of forest as well, with a very distinctive tree line, which would imply that it was climate, not livestock that contributed to most of the meadows).
Maybe it is because the summers are warm over there, with many sunny days. If so, then they are like the California Sierras (which also has a big alpine area). Whereas the Cascades (and Canadian Rockies) have very short summers. Maybe the European Alps are like the California Sierras, with the addition of some really high peaks to add to the glaciers.
Anyway, here are some pics -- All of these are in the Vanoise:
If people are curious, I have a bunch more pictures on Flickr (and you can see bigger versions of these):
I haven't gotten around to the rest of the Alps, but almost all of our hiking was above treeline.