What is tearing the bark off my trees? ASK THE HORT AGENT
Question What is tearing the bark off my trees?
Answer There are multiple layers of bark on a tree. Most folks are referring to the rhytidome or outer bark when they say “bark.” As trees grow, they expand. The outer layers of cells die and then split apart to accommodate the expanding cells underneath them. This process is most obvious in the trenches formed between the bark of pine or oak trees. A good visual explanation is Tommy Boy (Fat guy in a little coat). http://www.youtube.com/watch?v=oGWbt3DSje0&feature=related
Bark pops off (or exfoliates) in different patterns for different types of trees. All bark flakes off constantly like skin flakes off people. However, bark can pop off in small pieces (like a maple or poplar tree) or large sheets at a time (like a crape myrtle or river birch). Every tree falls somewhere between a red maple and a river birch.
While bark may serve as protection for trees, it also serves other purposes. Insects and small animals (like tree frogs) often hide under and between pieces of bark. Birds tear off bark in search of insects. The pileated woodpecker (aka Woody Woodpecker) uses his beak to tear off large volumes of bark in search of bugs. Larger animals like coons, possums and squirrels line their nests with soft bark. Many a small animal breathed its first breath on a bald cypress bark bed.
Large animals may have other uses for bark. Deer use bark to scrape the soft velvety coating off their horns. Bear and cats (bobcats and mountain lions) will sink their claws in the bark of trees. This is a means of marking their territory and grooming their claws.
The woodpeckers are knocking off dead bark, but no damage results from their actions. Coons and possums generally tear off enough to make a nest. They typically remove sections that are easily removed. Again, no damage results.
Tree problems occur when the living tissues under the dead layers of bark are damaged. Beavers, squirrels and deer are the most damaging to trees. Cats and bears may do some damage, but these animals rarely interface with homeowner landscapes. Starting a bobcat or black bear manicure service will probably not affect the average bark tearing problem.
Young humans (aka kids) have also been known to tear off bark. Their damage is easier to trace since they often carve their name or initials into tree bark.
For more info about trees with interesting bark, visit http://www.aces.edu/dept/extcomm/specialty/bark.html If you don’t have internet access, then call 910-893-7530 or email gpierce@harnett.org
British researchers now say that squirrels and kids have something in common. Both may tear the bark off trees to impress their boy or girlfriend. http://news.bbc.co.uk/1/hi/england/gloucestershire/4715315.stm Luckily, squirrels don’t know how to operate a pocket knife.
Gary L. Pierce
Horticulture Extension Agent
Harnett County | 
