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The Power of Photoperiod

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Red fox pouncing on prey (photos: skeeze, Pixabay)
“The most powerful stimuli for plants and animals is something called “photoperiod” (the period of light during each day).”

March 20th.

Happy Vernal Equinox! This marks the first day of Spring in the Northern Hemisphere; when day and night are of equal length. At this time of year, we are gaining three minutes of daylight per day! That's the biggest jump we'll see all year. If that's not reason to celebrate, then what is?!

These three minutes a day may be barely perceptible to modern humans who are relatively disconnected from the natural world, but our flora and fauna are totally plugged into it.

The most powerful stimulus for plants and animals is something called "photoperiod" (the period of light during each day). An organism's seasonal response to photoperiod is an extremely predictable reaction.

Lengthening days are a sign of spring to those of us with cabin fever, while plants and animals take this cue as a signal that the most favorable conditions for reproduction are upon them.

A plant knows just when to flower because it uses the daily cycle of light and dark as an internal calendar; flowering right on schedule for what is most advantageous for its particular life history strategy. Other environmental cues like temperature and moisture can alter the program, but the photoperiod is paramount.

The budbreak of willow in early spring - gracing the stark early spring landscape with their fuzzy silver catkins (photo: Monika Schroder).

The budbreak of willow in early spring - gracing the stark early spring landscape with their fuzzy silver catkins (photo: Monika Schroder).

Changes in our climate are impacting otherwise highly predictable schedules. While that is alarming, I am happily struck by just how remarkably adaptable the natural world is.

What are you seeing out there on the early spring landscape?

Look for amorous ravens, hard-working foxes, sky dancing, and bees on red maple flowers.

Did you know…? Pussy willow catkins are an important source of protein-rich pollen for bees in the early spring. To learn more about willows, and the benefits they bring to landscape biodiversity, I recommend this wonderful plant profile by Pamela Johnson of The Wild Seed Project.

I hope you enjoyed this Phenology Note!

Join me in witnessing the seasons of our wild world.

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#ThePersonalEcologistI partner with eco-minded landowners to create thriving wildlife habitats in their backyards, gardens, fields and farms, woods or campuses - at any scale.I have 25 years of experience in my field, and a lifelong commitment to wi…

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I co-create biodiverse habitats with eco-minded stewards throughout the Northeast - at any scale.

I have 30 years of experience and a lifelong commitment to wildlife conservation.

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Deborah Perkins