As I noted before, I rather enjoy the changing seasons found here in Pennsylvania, although the coldest months of winter are less and less inviting as I age. If I have a favored season, it is autumn, with spring a close second. One of the reasons for my autumn choice is the beauty of our countryside as the leaves begin their color changes.

Some basic biology reminds us that leaves’ green color is determined by the green pigment in them called chlorophyll. Chlorophyll allows the leaf to capture the sun’s energy, and with carbon dioxide and water, produce food (sugars) and release oxygen. This process is called photosynthesis.

As the amount of daylight lessens and lessens as autumn approaches, the deciduous trees begin preparing for the rigors of winter. Lessening daylight triggers the plant to produce a layer of cells between the twig and the leaf stem. This causes the chlorophyll to eventually disappear. With the chlorophyll pigment now decreasing the other pigments (always present) are now dominating the leaf’s color. These pigments are xanthophyll (yellow) and carotenoids (orange). As most of the chlorophyll dies off, sometimes the red pigment anthocyanin appears in certain leaves.

Different tree species usually sport characteristic fall foliage. Sweet birch, American beech and white ash are yellow. Sumac, red maple, and black gum are red, while sugar maples show off their “orange” leaves. Autumns with relatively cool nights and rather dry conditions result in the most colorful and lingering leaves.

An early October hard freeze will kill off the pigments too quickly, while hard rains and winds will bring those beautiful leaves down before you get the full appreciation.

I did want to remind you that coniferous trees (evergreens), like a white pine, do lose their leaves as well. However it is not an entire “drop off” such as birch or maple. In October, find a white pine and notice that many needles are browning, and weeks later those are now discarded. Most of the pine’s needles do remain. If you ever have taken that nature walk or picnic and found a stand of white pines, you’ve found out that the bed of needles underneath offers a great spot to sit and relax.

Pines, hemlocks and firs have very thin leaves which lose less valuable moisture through a bitter windy winter. Broad-leaved deciduous trees would not sustain themselves if they kept their leaves and would lose too much critical water.

I have noted in my “records” that generally Oct. 12-20 offers the best leaf viewing in the Times News area. The higher Pocono Plateau may be a bit earlier. Now get out there, take a walk, bike ride or jump in your vehicle and enjoy the splendor of autumn leaves.

Nature Hint: Hawk migration is beginning a new phase with accipiters (sharp-shinned and Cooper’s hawks) now passing Bake Oven Knob in bigger numbers. Even if you don’t venture to the mountain top, follow the daily migration totals online at HawkCount.org, and bookmark Bake Oven Knob. The daily totals get posted a few hours after dark.

Test Your Outdoor Knowledge: Most every deciduous tree has its own characteristic leaf shape; however the _____ has three different shaped leaves on their branches. A. black gum, B. dogwood, C. sassafras, D. gray birch.

Last Week’s Trivia: Shagbark, pignut and bitternut are all types of hickory trees.

Contact Barry Reed at breed71@gmail.com.