Northland Nature: Roadside leaf colors beginAs we step into this new month of September, we enter a time of shortening daylight. Sunrise is now at about 6:30 a.m., while setting is at 7:50 p.m.
As we step into this new month of September, we enter a time of shortening daylight. Sunrise is now at about 6:30 a.m., while setting is at 7:50 p.m.
These 13 hours and 20 minutes of light rapidly lessen through the days and by the end, after the autumnal equinox, the bright time of day is less than the dark.
The response to this change in nature is overwhelming and cannot
go unnoticed by the passerby.
Birds that have been gathering in restless flocks and family units lately are more on the move now. A trip to Hawk Ridge any day at this time will give us grand views of various raptors flying by, but also moving songbirds, geese and even migrant insects.
We usually think of the monarch butterflies when it comes to southbound insects in September and, yes, they do fly by even though this season seems to have been a slow one for them.
But another insect, the green darner dragonfly, is also migrating. Indeed, I think some days they may appear to outnumber the raptors at Hawk Ridge.
Migrants of another type can be seen as we move into autumn as well. In the next several weeks, snakes will be traveling overland to be in the area of the sites where they hibernated last year.
Besides the migration, more is happening. Late season insects and spiders use these days to reproduce before the chill moves in. Fruits, berries and nuts have been reaching maturity and ripening. Fall wild flowers of sunflowers, asters and goldenrods proliferate, slowly forming new seeds.
And the leaf color advances more each day during this scenic cooling month.
The heat and dryness of late August has influenced the plants; and even with this spring’s foliation being later than normal, the defoliation, the leaf drop, may actually be earlier than the usual time.
While walking and biking during the last days of August, I saw plants of reds and especially yellows from the roadside foliage. And now, in early September, I expect this leafy scene to intensify. We watch the arboreal colors each year and we never seem to get tired of the show.
Though colors can vary from red to purple to orange to gold to yellow, it is the first and the last of these, the reds and yellows, which are most common. Any observer of nature will notice in the woods of September and October that yellow leaves far outnumber the reds.
The yellow pigment, xanthophyll, was in the leaves all summer, but covered up by the dominant green color, chlorophyll. The shorter days influence the plants to break down the chlorophyll, allowing the yellows to be seen.
The red, anthocyanin, is a pigment manufactured by the leaves from excess sugars. It is therefore not as common as yellow. I find that red leaves are in trees at the woods edge or roadsides where ample sunlight allows it to be formed, rare in the shaded sites.
Also the temperature and moisture impacts the colors.
Some trees that are already starting to form red leaves are maples, dogwoods, sumac and the vine Virginia creeper, all in sunny locations. Yellows are appearing in the leaves of birch, poplar, aspen, cherry and maples with a tint of color also seen in ash, box elders and basswoods. Some of the birch, poplar and aspen were also dropping leaves, probably a response to the heat and drought.
However, along the trails that I walked and biked, the most yellow came from plants that were not trees. Several smaller and non-woody plants were lighting up the edges. Of these, two kinds were most common: milkweed, and its cousin dogbane.
Back in July, the milkweeds and dogbanes sparkled from these same sites with numerous pink and white flowers. The plants bloomed well this summer and the blossoms attracted a variety of insects, especially butterflies called fritillaries.
With pollination, the flowers faded to form seed pods and the leaves, no longer needed for food making, lost chlorophyll and became yellow. Were it not for this slow glow presently in the trailsides, we would not know how abundant dogbane is.
But now as we start this amazing month of September, we’ll do so with yellows and reds from some plants quick to change from the green of summer, and they tell us of what is to come.
Retired teacher Larry Weber is the author of several books, including “Butterflies of the North Woods,” “Spiders of the North Woods” and “Webwood.” Contact him c/o firstname.lastname@example.org.