News Release

National Park Protection Lets Forests Flourish

Date: February 7, 2017
Contact: Megan Nortrup, 202-339-8314

WASHINGTON – Trees are aging gracefully thanks to National Park Service (NPS) protection. At over 125 years old, Rock Creek Park in Washington D.C., has a significant number of very large trees—mature trees that have been protected from logging or disturbance because they are in a national park. These trees create a forest that helps maintain regional species diversity by providing habitat for wildlife and plant species that best thrive in older, more structurally complex forests. 

Many eastern bat species depend on trees—like those in Rock Creek—for roost sites, and certain birds will only nest in mature forests. And visitors certainly don’t mind a nice shady place to sit during the sweltering D.C. summer. 

According to a new study by NPS ecologists comparing forests across 50 national parks in the eastern U.S. to forests on the surrounding landscape, national park forests tend to have older and larger trees and more decaying wood and woody debris. The differences they saw echoed those between old-growth and managed forests.

As a whole, D.C.-area national parks provide older, more complex forest structure even including forests in Antietam, Manassas and Monocacy battlefield parks, which are in earlier phases of growth and have not been protected for as long as Rock Creek. 

“Healthy forests are messy forests,” said lead author Kathryn Miller. “Messy forests have trees of all sizes, both alive and dead. Both standing and fallen. And older, more complex forests, like the ones in parks, support a unique diversity of birds, bats, insects and other wildlife.”

“Almost all of the forests in the eastern United States, including many parks, were logged or converted to agriculture at some point in the past,” Miller said. “And now because of their protection, parks are some of the best examples we have of more mature eastern forests.”

Another sure sign that park forests are more like old-age forests than their neighbors is the abundance of dead trees and downed wood. Dead trees and dead wood might not sound like good things, but they’re actually vital parts of forest habitat. They provide the “room and board” for a variety of species.

A rotting log for example, provides the cool, moist and stable environment sought by many species of salamanders. And the insects and fungi that often occupy this woody debris are an important food source to other wildlife. The density of downed wood across eastern parks averaged more than twice the amount (135 percent higher) found in non-park forests. 

It is NPS protection that allows forests like these to develop and play an important role in our local and regional ecosystems.

About the special feature: The study by Miller et al., appears in a special feature of the journal Ecosphere focused on the National Park Service’s natural resources Inventory & Monitoring efforts titled, "Science for our National Parks’ Second Century." The special feature celebrates the 2016 National Park Service Centennial and includes 19 articles showcasing the breadth and depth of research being conducted in the National Park System.

Miller, K. M., F. W. Dieffenbach, J. P. Campbell, W. B. Cass, J. A. Comiskey, E. R. Matthews, B. J. McGill, B. R. Mitchell, S. J. Perles, S. Sanders, J. P. Schmit, S. Smith, and A. S. Weed. 2016. National parks in the eastern United States harbor important older forest structure compared with matrix forests. Ecosphere 7(7):e01404. 10.1002/ecs2.1404


About the National Park Service Inventory & Monitoring Division
The Inventory & Monitoring Division (I&M) provides natural resource science to America’s natural national parks. Each year I&M scientists and field crews monitor hundreds of vital signs, like water quality, animal populations, and vegetation, in parks across the nation. This health status information helps park managers care for their parks, leaving them unimpaired for the enjoyment of future generations. Learn more about I&M at 

Last updated: February 9, 2017