Signs of Autumn

As this extreme enlargement shows, western Massachusetts has begun to sport autumn colors among its ash and maple trees. Dry, late-summer weather and shorter daylight hours have contributed to the early shutdown of the leaves' green chlorophyll, uncovering the remaining colorful trace sugars and minerals.
We have a theory about why some trees go autumn earlier than others. Many trees live in marginal niches of soil nutrients, soil water reservoirs, and exposure to sun, shade, road salts, etc. As summer's end nears, some of those marginalized trees become stressed when they deplete one or more of several important nutrients and begin to draw on reserves intended for the next growing season. The stress unleashes a hormonal command to conserve the reserves by signaling the junction where the leaves join the branch to close the vascular gates. Unable to get water or absorb carbon dioxide, the chlorophyll then dies as the tree prepares to go dormant for the coming winter, prepared to take advantage of next spring and a gamble on a more provident summer.
The first significant frost provides a sledgehammer signal to those trees in more provident niches still sporting greenery by killing the still-functioning leaves. In our location, that frost can come anytime now.