Why are we cutting down trees?

White oaks are prominent trees in a healthy hardwood forest. They provide food for more than 400 species of Lepidoptera—the family of bugs and moths that form a large part of a bird’s diet.

White oaks are prominent trees in a healthy hardwood forest. They provide food for more than 400 species of Lepidoptera—the family of bugs and moths that form a large part of a bird’s diet.

Botanic gardens are places where trees are planted and nurtured. If you’ve been out to the Garden recently, you will notice a number of freshly cut stumps and sawed logs in certain areas. So why are we cutting down trees in the Woodlands? There are several reasons.

Most of the trees being cut are ash trees that have been killed by the emerald ash borer. According to the Pennsylvania Department of Conservation and Natural Resources:

The emerald ash borer is a half-inch long metallic green beetle with the scientific name Agrilus planipennis Fairmaire. Larvae of this beetle feed under the bark of ash trees. Their feeding eventually girdles and kills branches and entire trees. Emerald ash borer was first identified in North America in southeastern Michigan in 2002. In the years since that discovery, the beetle has spread into Minnesota, Wisconsin, Indiana, Illinois, Iowa, Kansas, Missouri, Kentucky, Tennessee, Ohio, Maryland, Virginia, West Virginia, Pennsylvania, New York, Massachusetts, Connecticut, New Hampshire, North Carolina, Ontario and Quebec.

Emerald ash borer feeds exclusively on ash trees in North America. Host species include green ash, white ash, black ash, blue ash, and pumpkin ash. Tens of millions of ash trees have been lost to this pest, which usually kills ash trees within 3-4 years of infestation.

We are proactively cutting the dead ash trees along the trails to reduce the risk of injury to visitors and staff, as well as structures and other plants, should the dead trees fall. We are also selectively cutting some other kinds of trees that are either diseased, have severe injuries or are interfering with the growth of more desirable trees.

Our Woodlands were clear cut in the 1920s when the mining industry moved in. The trees that sprouted after the clear cutting were never managed and invasive species infiltrated. In 2010, a tree inventory revealed that only 30 native tree species remained out of 120. Since then, we have taken an active approach to forest management. We have planted thousands of trees of many different species to increase the diversity of the forest and to provide important food for birds and other wildlife. By cutting dead, weak and undesirable tree species, as well as removing invasive plants, we are providing space, sunlight and other resources these young trees need to flourish.