The Spring Green Light

The Spring Green Light

By Steve Roark

For all you warm weather people out there, your time has come.  The vernal (spring) equinox is upon us, which is the official beginning of Spring, arriving this year on March 20. The event is not only a promise of warmer weather, it also plays a key role in determining what date Easter occurs, which can move around quite a bit year to year.

sun face 2.jpg

First let’s do the science stuff. As you know, days are longer in summer and shorter in winter because the Earth pivots on its axis as it orbits, leaning our hemisphere (the northern one) either towards the sun (summer) or away from the sun (winter). That change in the angle at which sun rays strikes the Earth determines how well it heats it up. Leaning towards the sun makes it appear higher in the sky, and the rays are more direct and warm more.  Leaning away from the sun in winter makes it appear lower in the southern sky, and the warming rays strike the Earth at an angle and so don’t heat as efficiently.  Twice a year though the Earth reaches a mid-way point in it pivot where the hours of daylight and darkness are the same, and these are called the equinox, which in Latin means “equality of night and day”.  As you know the other equinox is in September and is called the autumnal equinox.

The end of winter was a big deal long ago when growing local food was critical to survival, and so the beginning of the growing season was celebrated all over the world.  The spring equinox was a symbol of renewal and rebirth, and in Italy it was celebrated by planting garden and flower seeds, which is still a custom around Sicily.  The Hindu consider the equinox as a victory of good over evil, and they celebrate it with the “festival of colors”, where participants toss bright colored powders over each other while dancing about. In Japan the spring equinox is called Shunbun no hi and is a more somber celebration, where families get together and visit ancestral graves.  Lighting bonfires was a common way to celebrate the equinox in many parts of the world.

Recognizing the spring equinox goes way back. The famous rocks at Stonehenge in England are over 4000 years old and were constructed so that the sun would rise precisely between two stones on the equinox.  An ancient pyramid in Mexico was designed so that on the equinox the sun would light up one edge of the pyramid that looked like a serpent, which represented the Mayan god Kukulcan.

The date to celebrate Easter is determined by the equinox. The Bible describes Jesus Christ’s death and resurrection as occurring around the time of the Jewish Passover, which was celebrated on the first full moon following the spring equinox. But there were some differing interpretations of when to celebrate Easter, with some churches celebrating it on the day of the Passover, while others celebrated it on the following Sunday. So, to clear up the confusion, Emperor Constantine I formed a council in 325 AD, who determined that Easter would be celebrated on the first Sunday after the first full moon occurring on or after the spring equinox.


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Aliens in Your Neighborhood

Aliens in Your Neighborhood

By Steve Roark, Forester

If you know what to look for, you will discover aliens nearby, brutal ones bent on world domination. Some walk around, some fly, but the really dangerous ones blend into the landscape and slowly increase in numbers undetected until it’s too late and they take over.  This isn’t science fiction, but a nasty reality show called exotic invasive pests, and many are out to get our forests.

An exotic invasive species is a plant, animal or disease that is not native, but was brought in from another country and can spread rapidly because the forest has no built-in predators or disease resistance to them.  Some invasives were brought in on purpose to do some intended good, such as providing food for wildlife, or because they are pretty for landscaping. Some were brought in accidentally, from eggs laid on shipping pallets or in the soil of potted plants.  Some recent examples include the Emerald Ash Borer, which is killing native ash like a plague right now, and Hemlock Wooly Adelgid, that is doing a number on hemlock trees. Historically the worst invasive to hit our forests was the Chestnut Blight, a disease that all but wiped out a tree that once dominated our forests and was highly valued for its lumber and nut production.

Invasive plants are of most concern to me because they blend into native vegetation. An exception is Kudzu, which is highly visible because it can take a native forest with hundreds of species of plants and animals and turn it into a green desert with only itself for company.  I hate that stuff, and it’s just the tip of the iceberg, with dozens of invasive plants that aren’t obvious until their sheer numbers make them stand out and the forest is then in true jeopardy.

Invasive grass cartoon.jpg

The worst invasive plants are the ones that produce edible seeds spread by birds.  One mother plant can have her babies spread for miles around. Below is a listing of invasive plants that I have observed to be spreading rapidly and of greatest concern.  It is by no means complete, as the list of invasive plants in our area is depressingly long. If you own land, even just a house lot with an overgrown fence row, there’s a good chance you have an invasive.  You would help us all and the forest if you would learn how to identify them and kill them with extreme prejudice. They are most often found along woodland or fence edges, out of reach of the mower but still able to get sunlight. There is plenty of information on the internet, so just type in the name and stand back.

Privet was brought in as a landscape hedge that can tolerate heavy pruning.  It produces a small purple berry that is spread by birds. Autumn Olive was brought in as a food plant for mostly birds. It produces heavy crops of small speckled red berries that birds eat, but then fly off and poop the seeds out everywhere. It can spread rapidly.  Bush Honeysuckle was brought in as an ornamental and has small flowers like the vine honeysuckle you are more familiar with.  It produces a small red berry spread by birds. Multiflora Rose was brought in as root stock for ornamental rose grafts, for wildlife food, and for creating a living livestock fence.  It produces a large multi-stem shrub with nasty thorns and heavy crops of bird dispersed seeds. Bradford Pear wasn’t supposed to be able to produce viable seed, but it figured out how to anyway.  In early spring the white blooms can be seen everywhere. Birds spread the seeds, which grow into trees with genetics from earlier breeding stock that can include nasty thorns.

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Tree Wisdom

Tree Wisdom

By Steve RoarkTree tall.jpg

With area Arbor Days at hand I thought it appropriate to reflect on how intertwined our lives are with trees.  We not only use forest products multiple times every day, but their constant presence is inspiring enough to be used in literature, poetry, and music. A centuries old form of writing to teach wisdom is the proverb, a brief statement that expresses a general truth.  The Bible is full of them, and they are used by about every culture on the planet.  A way to juice up a proverb is to use figurative language, like: “He is like a tree planted by streams of water…”.  It makes for imaginative reading that will be remembered.  What follows is a listing of wise sayings where trees are expressively used.

  • Judge a tree from its fruits, not from its leaves. EURIPEDES
  • Love is flower like; Friendship is like a sheltering tree.  SAMUEL COLERIDGE
  • Stand still.  The tree ahead and the bush beside you are not lost.  EINSTEIN
  • If you climb up a tree, you must climb down the same tree. AFRICAN PROVERB
  • An ungrateful man is like a hog under a tree eating acorns, but never looking up to see where they come from.  TIMOTHY DEXTER
  • There is not a tree in heaven higher than the tree of patience.  IRISH SAYING
  • From a fallen tree make kindling. SPANISH PROVERB
  • When eating a fruit, think of the person who planted the tree.  VIETNAMESE PROVERB
  • The tree of silence bears the fruit of peace.  ARABIAN PROVERB
  • The tree of revenge does not carry fruit.  DUTCH PROVERB
  • Evil enters like a needle and spreads like an oak tree.  ETHIOPIAN PROVERB
  • The ripest peach is highest on the tree.  JAMES RILEY
  • A wholesome tongue is a tree of life; but perverseness therein is a breach in the spirit.  PROVERBS 15:4
  • A good word is like a good tree whose root is firmly fixed and whose top is in the sky.  QURAN
  • It is not the last blow of the axe that fells the tree.
  • Even the highest tree has an axe waiting at its foot. TURKISH PROVERB
  • Tall trees catch much wind.
  • He that would have the fruit must climb the tree.
  • The stronger the breeze the stronger the trees.
  • A chameleon does not leave one tree until he is sure of another.  ARABIAN PROVERB
  • It is only the tree loaded with fruit that the people throw stones at.  FRENCH PROVERB
  • You should go to a pear tree for pears, not to an elm.  PUBLILIUS SYRUS


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The Curiosity of Contrails

The Curiosity of Contrails             

By Steve Roark

You may not have realized it, but if  you look up on a clear day you will likely see a man-made cloud somewhere in the sky, trailing behind jet aircraft high up in the atmosphere. Contrails, short for condensation trails, are formed from the water vapor found in aircraft exhaust as a byproduct of fuel combustion. Natural clouds form from the same process of water vapor condensing in cool air as it rises, so technically contrails are clouds, just from an unnatural source.

Contrail formation is similar to what your breath does on a cold day, where a body temperature exhale full of water vapor hits cold air upon exiting your mouth and condenses into visible mini-droplets.  Only with contrails the exhale from jet engines is a toasty 1600 degrees Fahrenheit, that hits an air temperature that at cruising altitude is 30 to 60 degrees below zero, resulting in a rapid formation of ice crystals that form a bright linear cloud behind the aircraft.


As you may have observed, there’s a lot of variability in contrail formation. Some days you will see planes with no contrails, while others form contrails that evaporate a short distance behind the aircraft. But on some days the contrails last for hours and form ever expanding crisscross patterns in the sky.   Which it will be depends on what’s going on in the upper atmosphere.  If the air up there is warm enough and dry enough, the ice crystals evaporate shortly after formation. But if the air is cold and moist, then the contrails are long duration. This variability can be a weather indicator. Short or no contrail formation denotes a dry troposphere and may indicate fair weather.  Long lasting contrails indicate that the upper atmosphere is moist and rising, which it normally does with an approaching warm front, which may bring precipitation in a day or so.

In the right conditions, contrails can grow and form a cloud layer called Cirrostratus.  Besides water vapor there are other things in aircraft exhaust, carbon dioxide, hydrocarbons and such, but also a lot of tiny particles of soot and other solids.  These particles act as nuclei on which water vapor can form droplets in the condensation process.  Going from water vapor to visible droplets doesn’t happen just because it’s cold enough.  It can be well below freezing, but if there are no nuclei to form droplets onto there is no condensation.  It’s an oddity, but a critical one when it comes to cloud formation.  So, contrails under the right conditions will grow because the aircraft exhaust particles allow condensation of water vapor in the surrounding air, and so the contrail cloud endures and grows considerably larger.

Clouds of all kinds are pretty cool if you are observant, and it’s something you can do from anywhere. So let the inner child out now and then and be a cloud observer. Lying on the grass is optional, but fun to do with the kids. If you really get into clouds you can join an international organization called The Cloud Appreciation Society. A really good book on clouds is The Cloud Spotter’s Guide, by Gavin Pretor-Pinney.





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The Bad Rap of Snake Oil

The Bad Rap of Snake Oil

By Steve Roark

I have a friend who told a humorous story about being in a meeting where someone was speaking of things that he knew to be untrue, downright bovine excreta.  When he had taken all he could of it, he stood up, got up, slammed a dollar onto the table and cried out “gimme a bottle of that snake oil!” Snake oil is indeed a popular metaphor for anything being touted as true, but in reality is fraud. And those attempting to sell or convince you to accept something fraudulent are referred to as snake oil salesmen.  But snake oil started out as something that was genuinely helpful, so how did it become something derogatory? The answer lies in history.

Back in the mid-1800s over 100,000 Chinese immigrants came to the western U.S. to work on the Transcontinental Railroad.  The labor was hard, and so to relieve body aches they brought with them from China a liniment of sorts made of oil from the Chinese water snake (Enhydris chinensis).  The oil was rich in omega-3 acids which is known to reduce inflammation and joint pain.  As word got out, the desire to make and sell snake oil grew, and so a local substitute for the snake oil ingredient was sought.  Rattlesnake oil was originally used, but it had far less of the beneficial acid in it, and so was not as effective.

Snake oil label.JPG

That didn’t get in the way of making a sale however, and so the inferior American snake oil liniment was put on the market and sold. The late 1800s saw a boom in selling so called patent medicines that were advertised in newspapers and sold by traveling salesmen.  Some took the deception one step further, most notably one Clark Stanley. He made a splash at the World Exposition in Chicago in 1893 by making a show of taking live rattlesnakes, gutting them, then boiling them in water in front of an audience.  When the fat rose to the surface, it was skimmed off, bottled, and sold on the spot. He sold out as fast as he could make it, and afterwards began selling “Stanley’s Snake Oil”, and did quite well.  The problem was that the snake oil product he later sold had no snake oil in it at all.  In 1917 federal investigators revealed that all the product had in it was mineral oil, probably beef fat, red pepper, and turpentine. The connection of snake oil and fraud was pretty much established after that, and western movies emphasized it even more by making the snake oil salesmen a common character.

Snake oil made from Chinese water snakes is still obtainable, and its formulation varies. It is generally a mixture of the extracted snake oil and some sort of carrier oil or salve. It is mainly emphasized as being good for arthritis.


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The Scoop on Sweetgum

The Scoop on Sweetgum

By: Steve RoarkSweetgum2

Sweetgum (Liquidambar styraciflua) is a common tree in our area, normally found growing in low areas where the soil is moist, such as near streams or drains.  The name comes from the taste of its hardened sap that bleeds from wounds on the trunk.

 The tree is easy to identify, with leaves distinctly star-shaped and with a small-toothed edge.  The bark is gray and furrowed with flat ridges that form a diamond pattern.  The twigs are showy in the winter with corky, wing-like protrusions.  The fruit is a spiny ping pong sized ball that hangs on well into winter.

 While not favored as a timber tree here, in the south it is much more prevalent, and millions of board feet are harvested for use in furniture and cabinetry.  With proper staining it can be made to look like walnut, mahogany, or rosewood.  Early pioneers used the sap to treat sores and skin problems, as well as for a chewing gum.   During the war, Confederate army doctors used it to treat dysentery.  The gum is available from pharmacies and is considered to have expectorant, antiseptic, anti-microbial, and anti-inflammatory qualities

 Sweetgum is not used by wildlife to any great extent, but goldfinch and purple finch eat the winged seeds, as do squirrels and chipmunk

 Historically sweetgum goes back a long way.  It is mentioned in a journal kept by one of Hernando Cortez’s soldiers in 1519 which describes Aztec ceremonies that included drinking a liquid amber extracted from sweetgum trees.

 Sweetgum makes for an interesting landscape plant.  In the fall the leaves often go through shades of yellow and orange before culminating in hues of red, crimson, burgundy, and purple. During the winter you can see the pyramidal form and distinct corky twigs.  The fruit, while interesting to look at hanging in the tree, are a nuisance on the ground, where they take several seasons to break down.  If you wish to plant sweetgum, it prefers moist to occasionally wet, slightly acidic, deep soils. It can adapt readily to poor soils that are dry in summer and can grow in full to partial sun.

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Be an Astronomer for One Night

Be an Astronomer for One Night

By: Steve Roark

TN Dept. of Agriculture, Forestry DivisionOrion


The winter night sky gives you the opportunity to see a few things you may not have thought you could see.  In one small part of the sky you can easily identify a constellation, name two stars, see a sun that has a planet orbiting it, and see a Nebula.  This will be the fastest astronomy lesson you’ll ever have, so hang on.

Find yourself a dark place on a clear night and look to the southeast an hour or so after dark.  Look for three stars lined up in a row that point down towards the 7 or 8 o’clock position.  Coming off these three stars is another row of three smaller stars pointing towards the 5 o’clock position.  If you can find these stars you’re officially looking at the constellation Orion, also called “The Hunter”. The first three stars pointing to the left represent Orion’s belt, while the ones pointing to the right represent a knife hanging from his belt.

The big bluish star to the lower right of Orion’s belt is called Rigel, a sun more than 600 light years away.  Rigel is a blue-white super giant, and its name comes from an Arabic term that means “the left leg of the giant”, referring to the figure Orion.

The big reddish star to the upper left of Orion’s belt is the star Betelgeuse (pronounce “Beetle-juice”), and represents Orion’s right shoulder.  When you look at Betelgeuse (a red super-giant star) you’re looking at the largest object you’ll ever see.  It is more than 600 times the diameter of our Sun, which is only around 865,000 miles in diameter.   Betelgeuse made the news a few years ago when astronomers using the Hubble Space Telescope verified that a planet is in orbit around it.

Here’s one more thing to look for in Orion.  Find the three stars going off to the right of Orion’s belt, his knife remember.  The middle one is not really a star, it’s a nebula, specifically the Orion Nebula.  A nebula is a tremendous cloud of gas and dust where stars are being born.  The Orion Nebula is over 1000 light years from Earth, so the faint light you see started out around 1018 AD.  This is about the time the Chinese figured out you could burn coal for fuel. So, astronomy and time travel.  How cool is that?


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