Got Nature? Blog

‘Twas the day before Arbor Day, when all through the park,
Not a creature was stirring, no chirp, squeak or bark.
The birds were perched on the utility wires with care,
In hopes that many trees soon would be there.
All types of squirrels, gray, fox and red,
Had visions of oak trees dancing in their head;
And mama with her overalls, and I my work jeans,
Were prepared and ready to make the park green.When out in the park, there arose such a clatter,
I sprang to my window to see what was the matter.
Away out my door, I flew like a flash,
Running to the crowd that was gathered ‘round the ash.The dead looking tree with no leaves to show,
Gave a glimmer of midday through its branches to objects below.
When what to my wondering eyes came ‘round the corner with ease,
But a miniature truck and in the bed, eight tiny trees.With a little old driver, so lively and quick,
I knew in a moment it must be Mayor Nick.
The trees looking so healthy and flourishing as they came,
He whistled and shouted and called them by name:”White Oak! Red Cedar! Silver Maple and Black Cherry!
Cottonwood, Black Walnut, American Beech and Hackberry!
It is time to grab your gloves, shovels and spades!” He did call,
“Now plant away! Plant away! Plant away all!”With his blueprints out, he started to show,
Where in the park each tree would go.
So excited and anxious with all my gear, I flew
To the truck full of trees, and Mayor Nicholas too.

And then, in a moment, I heard on the road,
The roaring of more trucks with trees overflowed.
As I lifted my head and was turning around,
The city forester and many arborists came with a bound.

Mayor Nick had called in the professionals to help us out,
So we all would understand what this project was all about.
“Before we start planting, I want to explain
the benefits from these trees the city will gain!
Trees increase property value and improve living conditions.
They also relieve stress and help with (CO₂) emissions.
Better air and water quality and sound barriers too,
And the best part is the beautiful new view!”

After Mayor Nick’s speech, the city forester stepped in.
“Whose ready to plant some trees?” he said with a grin.
The crowd cheered, and the project was now on its way,
Making the park beautiful and green in honor of Arbor Day.

First thing we had to do was remove the dead trees.
The park was originally filled with ash, which was a feast for EAB.
The arborists cut all the trees down one by one.
There was so much help, in no time the cleanup was done.
As we finally started planting, the professionals came around,
Making sure we were putting the trees properly into the ground.
I learned that you cut and remove only ⅓ – ½ of the B&B.
Then you check the roots, the most important part of the tree.

If the tree has spiraling roots, all four sides must be sawed,
So the tree’s way of nutrient uptake and anchorage is not flawed.
It is also important that the root flare is not below the soil line.
Many people tend to bury it, thinking their tree will be fine.

Before planting your tree, consider the tree’s full-grown size.
Improper planting can cause the tree to die otherwise.
I’m so glad I decided to volunteer today.
I learned so much about planting trees the right way!

After countless hours of hard work and sweat,
Mayor Nick’s goals for the park were finally met.
He thanked everyone, and as he drove out of sight,
He shouted “Happy Arbor Day to all, and to all a good night!”​

Resources
FNR Majors & Minors, Purdue FNR
Prospective Students, Purdue FNR
We Know Nature! FNR: This is Your Classroom Project Video

​Erin Hipskind, Forestry Student
Department of Forestry and Natural Resources, Purdue University

Trees offer many functional and aesthetic benefits, but one of the most common is shade. Because of this, one of the most important aspects of tree selection and planting is placement. Improper placement of trees can diminish the value of the tree on the site. The tree can actually become a liability if it conflicts with infrastructure or just does not providing any useful shade at all. For shade where it’s needed most that also allows passive solar gain in the winter months, you must use an energy efficient design.

Figure 1  (Diagram by Greg Pierceall)

In this hemisphere, the sun is in the south, and the source of cold weather is in the north. Whenever possible, place openings for sunlight and radiant heat primarily on the southern exposure, then on the west and east. For energy efficiency in winter, use the low arc of the sun to capture the maximum amount of warmth through east-, west- and south-facing windows. Windows with a northern exposure are a source of cool air from prevailing winds during the hot months, so give the north minimum exposure and maximum natural protection in the winter.

When selecting trees for energy efficiency, don’t plant evergreen trees near the house on southern exposures. Trees may provide some shade and screening but will also block out the warming effects of the sun during winter months. When choosing trees for shade and solar gain, choose larger, deciduous-canopy trees that provide an advantage year round. Select good quality trees that are suitable for your location from a reputable source. See the publication FNR-433-W on the Education Store website for more information on tree selection and planting.

Correct placement is critical for an energy-efficient design and low maintenance as the tree grows and matures. Be certain that the mature height and spread fit the location before placing the tree. This allows the tree freedom to spread into the design space naturally without excessive pruning to prevent conflicts with the house. However, the tree still must be close enough to the house for the canopy to provide shade. A good rule of thumb is to plant the tree at least 20 feet from the house. For larger shade trees, you may need to plant as far as 40 feet from the house to insure room for growth (see Figure 1).

Trees help make homes energy-efficient by creating a cooling effect during the hot summer months or by allowing the passive solar gain during cold winter months. However, proper selection and placement is critical to make this work.

Resources
Tree Installation: Process and Practices, The Education Store
Tree Planting Instructions, Indiana Department of Natural Resources
Planting & Transplanting Landscape Trees and Shrubs​, Department of Horticulture, Purdue University

Lindsey Purcell, Urban Forestry Specialist
Department of Forestry and Natural Resources, Purdue University​​

“When it snows…
and temperatures drop,
That’s when you’ll hear
The Snap, Crackle and Pop.”

Few things can compare to the peacefulness of walking in a forest filled with snow covered trees until you hear a snap, crackle or an explosive “POP” echoing through the woods. What on earth was that? If the noise is followed by a “whoosh,” it may be a limb that just broke and crashed to the ground. If it sounded like a gunshot but nobody is there, you may be listening to the sound of a frost crack forming on a tree.

What are frost cracks?
Nobody knows for sure. You may hear one happen, typically on a cold late winter morning after a warm spell. They sound like muffled to loud rifle shots. Typically, these cracks occur on the south side of the trunk between two and five feet up the tree (when measuring from the ground). With leaves on, water is pulled upwards from tree roots through the xylem vessels by the differences in water potential from the air to the soil and escapes through the leaves (the soil-plant-air continuum).

Water in the plant is under a negative water potential, or in common terms, under tension. In the winter, when deciduous trees have no leaves, the water pressure in the sap becomes positive. A flow occurs where water moves up in the xylem and cycles down in the phloem (food conducting cells). The mechanism of this winter flow in temperate trees is not well understood physiologically. The sap increases in simple soluble sugars as the cold weather begins and increases until midwinter to work like antifreeze, depressing the freezing point of water. This is why maple syrup can be tapped in late winter.

Scientists are challenged to study the phenomena of frost cracks. They involve thousands of xylem vessels in a very narrow vertical line bursting all at once – as if a line of sap is too low in sugar concentration – and then freezes hard explosively bursting the vessels. After several growing seasons, most trees will heal over the crack, but callus growth makes them appear wider. Valuable timber logs can still be profitably harvested with frost cracks as millers can cut through them to minimize the defect.

Species with darker colored bark and thinner bark can be affected by frost cracks. Some genotype effects have been found in black walnuts at Purdue. Field conditions and topography that effect cold air movement can affect frost cracks. Most form on the southwestern section of the trunk, the area most affected by warming from sunlight during winter afternoons. Somehow, this conditioning sets up the tree when temperatures plummet to single digits (in Fahrenheit) or lower, especially after a warmer period.

So if you wander through the woods this winter, stop but don’t “drop” when you listen to the sounds of the trees.

“When the snow twinkles
and the skies are bare…
Temperatures drop
and a chill fills the air.
If you listen real close
and adjust your cap,
You just might hear
a tree go ‘Snap!’”

Resources
Bark Splitting on Trees, Cornell University
Video: How Do Trees Survive Winter? MinuteEarth
Winterize Your Trees​, The Education Store

Shaneka Lawson, Adjunct Assistant Professor
Department of Forestry and Natural Resources

James McKenna, Operational Tree Breeder
Department of Forestry and Natural Resources​​​​​