Fall foliage happening later this year

By Walt Young

For the Mirror

One undeniable truth I’ve learned during a lifetime of work and recreation in the outdoors is that the natural world does not adhere to the same rigid calendar we humans use to track the course of a year.

Nature operates by its own calendar. Even though so many natural events occur routinely every year, attempting to assign a specific day to some annual occurrences will almost always be wrong one way or the other. Just ask any fly-fisherman who tries to predict when a certain species of mayfly will hatch on his favorite trout stream.

Despite the unpredictable ways of nature, it occurred to me late last week that trees in our region seem to be in no hurry to make the transition from the green leaves of summer to the flaming foliage of autumn.

Most years, the ridges throughout of south-central Pennsylvania will be awash in yellow, red, orange, russet or bronze as each species of tree displays its own fall colors by the third week of October. Of course, some years tend to provide a much better show of fall colors than others. Predicting the “what” and “when” of fall foliage tends to be mostly folklore, so let’s look at some of the basic science behind how and why leaves change color.

Aside from evergreens, most trees in our part of the world grow new leaves each spring, and those leaves become individual food factories for the tree throughout the spring and summer. Leaves derive their green color from the pigment of an amazing substance called chlorophyll. Through an extraordinary chemical reaction, chlorophyll absorbs the energy from sunlight and uses it to transform carbon dioxide and water into sugars that the tree uses for food via the process known as photosynthesis. Most green plants rely on chlorophyll and photosynthesis for their existence.

As fall approaches, leaves stop their food-making processes, and the chlorophyll breaks down, allowing other pigments present in the leaves to show their color. The first of those, known as carotenoids, tend to be mostly yellow to orange in color. Carotenoid pigments are what produce the distinctive yellow colors of corn, carrots, daffodils and even bananas. Carotenoids tend to be present in the leaves of many trees and shrubs, which is why many of the first leaves to change color tend be yellow hues. Another group of pigments, known as anthocyanins, produce the bright reds and purples in fall foliage as well as apples, grapes, blueberries, cherries, strawberries, and plums. Most anthocyanins are produced in leaves later in autumn in response to bright light and excess plant sugars within leaf cells.

Beech trees turn a light bronze, while hickories will show golden bronze. Poplars will display leaves of golden yellow. Dogwood will turn a lovely purple. Red maples live up to their name with foliage of brilliant scarlet, and sugar maples will turn a beautiful orange. Oaks are the last to show their fall colors of red, bronze or russet.

While weather-related factors, such as rainfall, sunlight and temperature, can have some effect on the intensity and duration of fall foliage colors, photoperiod is the primary determining factor of when leaves make their fall transition. Photoperiod is the scientific term for the relative length of daylight and darkness for each day throughout the year.

Photoperiod is also the trigger for many of the remarkable transitions in nature, and fall foliage is certainly one of those. The shorter days of autumn start the biochemical processes in a leaf that ultimately cause the seasonal color changes.

The unseasonably warm and pleasant weather we have experienced most of this month may have influenced the late transformation of some leaves. Low temperatures can enhance the formation of anthocyanin pigments that produce the bright reds in maples and other species, but an early frost can weaken the red color.

Regardless of the factors involved, nature still works on its own schedule, so the answer to when the fall foliage peaks will be simply nothing more than a lucky guess most of the time.

New procedure

By now, most hunters and anglers are probably aware that the Pennsylvania Game Commission and Pennsylvania Fish and Boat Commission have changed the supplier for the processing of hunting and fishing licenses in Pennsylvania.

After years of the yellow licenses, tags and permits, those documents are now bright green. In addition, big-game hunters need to be aware of an important change in the procedure for tagging a deer, bear or turkey.

The time and location of the kill must be filled in with a ballpoint pen on front of the harvest tag as usual, but the date of the kill must be recorded by cutting out boxes with the month and date on the back of the tag. Apparently, this is a vehicle to make it more difficult for someone to attempt to reuse a harvest tag.

Most folks I’ve talked to recently are unaware of this change and that could be a problem if they are found with an improperly tagged animal. Complete information regarding the tagging of big game can be found on page 22 of the Pennsylvania Hunting and Trapping Digest that comes with your hunting license.


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