Posted by: ACRES Land Trust

  • 06/26/2023

Competing for the Canopy

ACRES commitment to protecting land goes beyond ensuring it remains undeveloped. We take a hands-on approach to make sure these places continue to improve under our care. Our stewardship team works to promote the health and biodiversity of these areas by creating or maintaining conditions that allow ecosystems to thrive.

When caring for forests, we use a variety of methods to reduce certain species in order to give others a chance to make their way to the canopy. We use fire and herbicides to thwart non-native invasive species that threaten to take over natural areas. We also “thin out” less desirable tree species through girdling.

Girdling is a forest management technique that involves removing a strip of bark around the tree’s entire circumference. Removing the bark’s innermost “cambium” layer prevents nutrients from being transported from the leaves downward, or from the roots upward. As a result, the tree slowly dies.

ACRES Stewardship Director Evan Hill said thinning out less desirable species through girdling is completed for a couple reasons, ultimately depending on the goals for or use of the property. ACRES performs selective thinning in protected lands being managed for sustainable timber harvests, as well as in some nature preserves.

Hill explained: “In certain areas this thinning may be completed to promote a more diverse understory/herbaceous layer, and in other areas, to promote a higher timber value while offering higher quality habitat to the countless critters that call the place home.”

In ACRES nature preserves, selective thinning takes place where historically, there would have been less canopy cover and a more diverse understory, such as an open oak woodland or oak savanna. After non-native invasive species management, our stewardship team removes less desirable tree species through girdling. The goal is to return the property to the state in which it would have persisted in the presence of more frequent natural disturbances, such as fire.

At this time, in portions of Ropchan Memorial, thinning is taking place as one of the early steps towards restoring an open oak woodland. In years to come, invasive species management will continue, along with the reintroduction of prescribed fire. On working lands, selective thinning is used to ensure the success of specific kinds of trees, including oak, hickory and walnut, for sustainable timber production.

Girdling trees allows a more gradual process of tree mortality. Instead of having several hundred trees piled up on the forest floor, this method allows them to die slowly and stay vertical for several years. In some cases a large tree may persist as a standing dead tree for a decade or more while providing habitat for countless insects, birds and small mammals.

This method is extremely useful when ongoing management is also needed. Invasive species management and prescribed fire become very difficult when paired with a large amount of downed woody debris.

Hill said because of the threats facing natural areas today, a “hands-off” approach to stewardship isn’t an option: “With the increased presence of invasive species and a lack of natural disturbance, it is nearly impossible for natural succession to occur as it once would have.”

As land stewards, promoting or increasing biodiversity within the preserves is a top priority for ACRES. The more diverse an area, the healthier the ecosystem will be.

“A diverse plant community supports more insects, which attract more birds and small mammals, and so forth,” Hill said.

The biggest threats to biodiversity include the presence of non-native invasive species, habitat loss and on a local scale, the lack of natural disturbance.

Our goal is to restore these places through stewardship activities such as invasive management, prescribed burns and selective thinning/harvests so the land once again can support a high level of biodiversity. Through these “hands-on” conservation efforts, we hope these areas ultimately return to self-sustaining ecosystems requiring minimal intervention to remain healthy.

This article originally appeared in the Summer 2023 ACRES Quarterly, mailed to members each season. The 20-page Quarterly features ACRES news, stories and events. You can subscribe by becoming an ACRES member with a donation of $20 or more. Click here to learn more!