Saturday, October 8, 2011

Unusual Fall Colors in New England

View of the expanse of forest over the Hudson Valley in New York State on October 6th as seen from the top of Millbrook Mtn. Most of the trees are still green, except for several of the maples which have various shades of yellow.
As luck would have it I was able to combine work and pleasure with a trip to New England this year right at the time that it is usually at the peak of fall colors. It is so popular for people to want to view fall colors that it has become quite an industry, especially for regions famous for colors such as New England. In fact it was next to impossible to find even a room to stay this weekend since so many people planned to see the colors. Weekend festivals were also planned when the colors should peak. However, if phenological events like fall colors were so predictable just from the calendar date then there would no need for scientists to get more data from programs like project budburst to document the pattern! Mother nature made at least a few people I saw today disappointed or even mad! Instead of the classic pattern of intense reds, orange, and yellow we mostly saw a lot of green, some brown, a lot of dull yellow or maroon and every once in a bright red maple or dogwood. So why have the fall colors been so different this year?

As we described last month leaf colors are a product of many factors, mostly having to do with weather or climatic patterns combined with changes in daylength and the characteristics of each tree species.

Every year trees begin to prepare for the winter season as the days get shorter, but whether this leads to bright fall colors depends on many aspects of weather and climate. As we saw in much of the Rocky Mountain region a few years ago, if a hard frost occurs before colors have had a chance to develop you then are left with leaves that are abruptly killed by frost. So they turn brown, and may not even fall off the trees for months. On the other hand if you do not get crisp fall weather with cool nights and warm days you will miss peak fall colors as well. This appears to be the case this year. New England, and much of the east coast has had a really bizarre summer and fall weather this year. It is one of the wettest seasons on record, and also until very recently a warm season as well. Heavy cloud cover and rain generally leads to warmer night temperatures, which can retard or delay the hardening off process. This has resulted in many species of trees and shrubs keeping leaves green well into the fall season. Early turning species like green ash and red maple have slowly turned their leaves yellow or brown then shed their leaves before full colors developed on them. As of this writing (October 8th) the principle colors I have seen in the Hudson Valley region of New York and the Berkshire Mountain region of western Massachusetts have been various shades of yellow on maples (mostly sugar maples and red maples), with some scattered shades of red. In the mountains, shrubs like blueberry or huckleberry which would normally be brilliant red are mostly a maroon or dull red color this year. At higher elevations in the Berkshire and Green Mountains you can see more colors, but still, as local residents will tell you, it is a far cry from the brilliant rainbow of colors that people usually expect to see this time of the year.

All of this underscores the key point that nature is quite variable, and most of these patterns which seem at first glance to be a simple seasonal pattern are in fact a complex interplay of biological and environmental factors. This is what makes the study of ecology so challenging, and why it is so valuable to carefully document these patterns year after year with programs like budburst! Each year is often quite different and a product of the unique combination of factors that influence plants. Perhaps as we improve these records and observations both by having them over a wider range of places in the country and by seeing how things vary year to year, scientists can better learn how all these factors work together to create the amazing patterns of colors we see. In any event it can make fall observations quite interesting. There are plenty of surprises and mysteries yet to solve, and much to think about when you are out making phenology observations. I look forward to seeing what budburst volunteers discover in how the fall continues to develop both here in New England and other parts of the country!

Paul Alaback

October 10th update from Sunapee, New Hampshire:
Still an unusual pattern up here in the North. Very warm fall, even 80 degrees today! But clearly the red maple is in full color here, many are bright red, paper birch and sugar maple also in color, mostly yellow but still with some green leaves. Most other trees still green. Looks like the colors are changing fast up here and cold weather will be coming soon.

Photos: (all taken by P. Alaback October 5-8th)

top left: red maple leaf with tinges of red
top right: red maple turning yellow in the Shawangunk Mountains (Mohonk Preserve).
middle left: flowering dogwood shows more consistent reddish colors in woodlands on the campus of the Institute of Ecosystem Studies in Millbrook, NY.
Bottom: A large sprawling red maple on the top of the ridge of the Shawangunk Mountains shows a light yellow color.

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