The changing bark of trees is an undeniable calendar. The bark of trees changes color before any other obvious signs of spring present themselves. Around here, the willows are the most obvious. Their thin, drooping branches become a stunning yellow. You can spot them among the darker trees from miles away. If you wait for the pear trees (above) and crab apples to bloom before you say, "It's spring," you will have already missed the flowering of the maple trees.
The trouble with closely observing a spring, as I did ten years ago, is that one can never do it the same way again. Each spring I feel a small amount of sadness when I observe the changes. You can only become aware of something for the first time once. Ten years I noticed spring for the first time, and now, as much as I enjoy watching it come on, it feels old hat. There is nothing like the first time you rip off a branch from a flowering tree and take it home.