Today's News
A/CPB
Leaf-Out Update: February 21, 1997
Amazing results to report! Our friends at Largo High School in Largo, Florida are the only people in all of North America who say they have seen leaves!
February 4, 1997
"I saw a number of Red Maples near a park. They were all with new leaves and some even
had flowers. On 2/16 the oak trees started to bloom their catkins. It is a wonderful site. Another sign of spring for us in FL are the Bald Cypress trees losing their leaves and ready to start budding. That was also happening on 2/16. Spring cannot be far off for the folks up north." Largo High School, Grade 9 (shapiroa@concentric.net)
According to Jo Leland in Houston, "Temperatures in Texas have been a little cool, so the usual burst of spring in early February has not occurred. As of February 19th, the trees are getting closer each day, but temperatures have just not stayed warm long enough." (joleland@tenet.edu)
How to Report Leaf-Out:
We hope you're ready to report leaf-out in your region. Simply press the blue owl button on the left and a Field Data Form will appear. Remember, your leaves must be the size of a U.S. quarter, our definition of leaf-out. By the way, if you have spring fever, we recommend a daily dose of this activity.
Branching Out
Wood you like to join the maple sugaring contest we announced in our last report? We didn't mean to leave you out! Which of the budding scientists will you root for, Vermont's or Minnesota's?
Challenge Question #2
"Whose sugaring bucket will fill first, Vermont's or Minnesota's? What date do you predict the first bucket will be full?"
To answer this Challenge Question please follow the instructions at the end of this report.
Meet the contestants:
Both contestants will tap their trees on March 7th. Visit this page regularly. When the sap begins to drip into the buckets you'll know spring has begun--and the race is on. To make your prediction, watch temperature readings for Montpelier and Minneapolis. Here are some other signs that the sugaring season is on:
"Crows congregating and singing, icicles dripping on the branches, watering trickling on the roads, snow receding from the base of the trees….these are all signs it's time to get ready to tap," explains Beth Allen, the Minnesota team's top tapper.
"Temperature is very important. Four to 5 days in the 40's with freezing nights usually starts the sap flowing. Because these temperatures occur at about the same time in Vermont and Minnesota, the sugaring seasons are similar. According to local records for the Minneapolis area, the earliest season began on Feb.14 and the latest was on April 4. The average time is early to mid March. For this contest, we have agreed to set the first tap on March 7th.
"Roughly how long might it take for a full bucket to be produced? It all depends on the weather, but a bucket can fill in as little as one hour! "A 'full bucket' will be defined as 3 gallons.
"The size of the tree does make a difference in the amount of sap yielded. (One tap for a tree 10 inches in diameter and another tap for every 10 inches is the standard used by sugar makers.) We will each use only one tap. We are working together to select trees as similar as possible. We're measuring the tree's circumference, estimating its height, the size of the crown, and exposure to light."
"Why do you think sap flows in the spring?", we asked in our last report. Thanks to students in Tennessee, Vermont and Maine for sending the theories below. You'll also find comments from Vermont Forester Paul Cate below. He is a Forester from Montpelier, Vermont who has tapped maple trees for more than 25 years.
From: TENNESSEE
Dear Journey North,
My name is Alicia. I think the sap starts to flow in the spring in order to
bring energy to the top of the tree so that the leaf production can begin.
The trees are dormant in the winter and with the increase in the
photoperiod, warm daily temperatures, and cold night temperatrues this
stimulates the sap to move up the tree. The maple tree needs energy to
produce new leaves for the coming summer and photosythesis to occur.
Thank you,
Mrs. McGinley's class
MCGINLEYL@ci.maryville.tn.us
From VERMONT:
My name is Mandy V. and I am a third grader at Ferrisburgh Central
School. In the winter, sap freezes so it won't run. In the spring it
starts to flow and there are no leaves to take the sugar that is why
the sap is so sweet. In the summer the leaves take all the sugar so it
is sour. In the fall there is no sugar left for the sap to make it
sweet.
lthurber@panther.middlebury.edu
From MAINE:
After much discussion we have decided that the trees are starting to wake
up from their winter nap. The sap in the tree is like our blood. It
carries good things that we need to all parts of the body, or tree. The
tree needs to send nutrition to the new buds from its roots. The buds can't
make their own food yet. The sap starts moving when the weather starts
to get warm so that the buds can get nutrients and start to grow.
Ms O'Neal's grade 2-3
Wesley Elementary School
Wesley, Maine
doneal@acad.umm.maine.edu
From: MAINE
Dear Journey North,
About the sap - we think it happens in the spring
because in the spring the tree has to make new leaves, twigs, and seeds.
That's why the sap runs.
From, Josh Mi. and Jeff
Grade 5, Pemetic, Southwest Harbor, Maine
Fran Howley grade5fh@pemetic.u98.k12.me.us
Here is Forester Paul Cate's explanation as to why sap runs in the spring:
"Actually, sap flows anytime when the trees are dormant (not growing) and there are sufficient temperature fluctuations above and below freezing. Trees could be tapped in the fall but the sap tends to be about half as sweet as in the spring.
"In spring the thawing days, 40-45 degree temperatures cause an expansion of gases (CO2) and sap. This creates pressure in the tree and the consequent runs of sap from any tap holes. Below freezing nights cause a contraction of the gases and sap, and a pressure reduction in the tree. So, sap will flow whenever pressure in the tree is greater than the atmospheric pressure.
"Starch stored in the wood cells is not readily changed to sugar by enzymes until the wood temperature reaches 40 degrees. Between 40-45 degrees the starches change to sucrose and go into solution in the sap. Above 45 the enzymes no longer convert starch to sugar. This explains why early and late runs of sap are usually not as sweet as the midseason runs. The starch-to- sugar change begins the process of breaking dormancy, preparing the buds to open and the leaves to expand."
How to Respond to Journey North Leaf-Out Challenge Question # 2
- Address an e-mail message to: jn-challenge-leaf@learner.org
- In the Subject Line of your message write: Challenge Question #2
- In the body of the message, give your answer to this question:
Challenge Question #2
"Whose sugaring bucket will fill first, Vermont's or Minnesota's? What date do you predict the first bucket will be full?"
 Vermont's Tree (44.15 N, - 72.34 W) |
Minnesota's Tree (44.55 N, -93.31 W) |
Please include the name of your school and your location so we can credit you properly for your answers!
The Next Leaf-Out Update Will be Posted on March 7, 1997.