After a wind at Crossroads…a strong branch-breaking blow, we notice that damaged evergreen trees are dripping sap. Injured trees do that. So do fresh Christmas trees.
Technically, once a Christmas tree has been chopped down, it is dead. But death in a tree is like death in a human or animal.
When an animal dies, its heart stops beating and blood stops circulating, Most body functions cease. But the top of tree can continue to function even after it is separated from the roots. Water is absorbed and moves through the plant without the aid of a heart. And strangely, needles continue to function even though the tree is dead.
This means that when we cut down or purchase an evergreen tree, it can stay nice and fresh for as long as it continues to absorb water. But when we cut and move a tree, we break and bruise the branches and the bark. As long as the tree is fresh, sap will ooze from the wounds. This process is called “pitching.” Sticky sap can be annoying when we decorate fresh trees, but this adaptation has real survival value.
In nature, trees are injured in many ways. Other trees fall on them, ice and wind storms break their branches, animals take bites out of them and insects invade. When a tree is cut or bruised, the sap rushes to the site of the injury where is hardens to form the plant equivalent of a scab to keep germs, fungus and insects out of a tree.
Some of the greatest damage to evergreens is done by bark beetles. The female insects bore holes through the bark and lay their eggs. When the beetle larvae hatch, they feed on the living plant cells–the very cells that transport water, minerals, and nutrients. If an infestation is serious, the tree may wilt or even die.
Equally nasty, bark beetles carry fungus spores. Trees infected with disease-causing fungi begin to decompose while they are still alive. Not good.
When insects attacks, healthy trees fight back!
As soon as an insect penetrates the bark of an evergreen, the tree pitches out. It squirts globs of sticky sap and the sap engulfs the insect. Of course, only strong, healthy trees are able to pitch out. Trees weakened through age, drought, leaf loss, or diseased are unable to pitch. Weak trees generally lose their war against insects.
What happens to the insect when the tree pitches out? Well, the insect is more or less embalmed in the sap and preserved—-perhaps forever.
Fossils evidence indicates that trees have had sticky sap for at least 220 million years. And what to do call that hardened sap, the translucent golden gem that sometimes encases insects of the past? We call it amber.
Sap from a fresh Christmas tree is not likely to become a gemstone, but as long as trees are absorbing water, they can pitch out and that sticky stuff can get on hands and clothing.
At Crossroads, birds are taking advantage of the emerald ash borers which are killing our ash trees, but they still come to the feeders at the Collins Learning Center. And the number of our feeders is growing as we develop our Accessible Bird and Butterfly Garden around our building. Our feeders are temporary as we observe behavior patterns of the birds. But we now have a number of feeders which are easily observed from the Entry Level of the Learning Center. Watching the birds come and go and identifying species is fun, but birdwatching becomes more rewarding when observers take note of behaviors—how do the birds approach the feeder? how do they interact with each other? how do they respond to danger?
On Sunday, December 11 at 1:00, Crossroads will hold a program called “Bird Behavior Watching.” Learners of all ages are welcome to join the naturalist in the warmth of the Learning Center to observe our birds and to learn more about the fascinating creatures who survive our Door County winters. The program is free and open to the public. Meet in the Entry Level of the Collins Learning Center.
The Monday Movie on December 12 at 2:00 will be the documentary “Lakeshore Guardians, The Story of the United States Life-Saving Service in Wisconsin.” Several Door County stations are featured and the sad, but seasonal story of the Christmas Tree Ship is discussed. This educational film is free and open to the public.
Crossroads at Big Creek is a donor-supported educational facility made of the Big Creek Preserve, The Cove Preserve, and the Ida Bay Preserve. December hours at the Collins Learning Center, located at 2041 Michigan just east of the Roundabout in Sturgeon Bay, is open 2:00-4:00 and during scheduled activities.
Sunday, December 11
1:00 “Bird Behavior Watching”
Learners of all ages are welcome to join the naturalist in the warmth of the Learning Center to observe our birds and to learn more about the fascinating creatures who survive our Door County winters. The program is free and open to the public. Meet in the Entry Level of the Collins Learning Center.
Monday, December 12
2:00 Monday Movie: “Lakeshore Guardians, The Story of the United States Life-Saving Service in Wisconsin”
In this documentary, several Door County stations are featured and the sad, but seasonal story of the Christmas Tree Ship is discussed. This educational film is free and open to the public. Lecture Hall of the Collins Learning Center.