Tree Time Part 2: Creating a Refuge

January 11, 2011 by Melissa McMasters

A few days ago, we told you about several of the impending threats to the trees in our parks. Now we'll tell you a little more about what we're doing to fight these attackers, and how you can help out.

Preserving Pittsburgh's Trees: Action and Recovery
We're far from the only organization working to preserve trees in Pittsburgh, so we've been working with our partners (like Tree Pittsburgh, the Shade Tree Commission, and the City of Pittsburgh) to develop a blueprint for our collective work. The purpose of the tree action plan is so that everyone involved in managing components of the urban forest in Pittsburgh can have a unified vision.

Inspecting trees

We convened experts from around the country in November 2010 for a tour of our parks and a discussion of the threats they’re facing. The group of entomologists, soil scientists, foresters, and nursery managers confirmed our suspicions that the City of Pittsburgh could potentially lose up to 60% of its native tree population in the next 10 years without intervention. Following this assessment, we began to draft a plan that would increase reforestation and create species refuges in the parks.

We realize that we don't have the resources to save all the trees that are in danger, but we can save some. The purpose of the Tree Action Plan is to minimize loss and speed recovery. And in species that are threatened with eradication, our goal is to preserve enough trees that we can save the species.

Saving the Species
Continuing advancements in DNA research have provided hope that threatened tree species can live on. Our work with the American Chestnut Foundation’s chestnut breeding program, along with our propagation of genetically diverse London plane trees from Schenley Plaza, have provided experience with these techniques. (Read more about those two projects here.) Ash trees find themselves in a similar situation to chestnut trees decades ago: facing a threat that will completely wipe out the population without active attempts to save the species.

Our priority this January is to identify specimen ash trees in the parks as candidates for preservation. Ideally, we’d identify at least 100 trees and have them tested for genetic diversity using the process that was undertaken with the Schenley Plaza trees. We’d like a large enough gene pool to guarantee diversity within the population.

Chestnut orchard

These trees would be considered part of a “refuge,” and would be treated by arborists and monitored regularly. The seeds from these trees would also be collected, with the U.S. Forest Service providing a seed depository. The seeds can help to repopulate the forest after the threat has passed, and/or form a basis for a program that attempts to breed a pest-resistant ash tree. (This article discusses similar efforts across Pennsylvania.)

2011: The Year to Treat
According to our resident tree expert Phil, 2011 is the year for homeowners to treat their at-risk ash trees, because the timeline of the emerald ash borer infestation suggests that 2012 will be too late. If your ash trees are already showing symptoms, they may be too far gone, but if not, you may be able to save them by contacting a certified arborist and having them treat the trees.

On the other hand, if your trees at home are exhibiting evidence of oak wilt, take them down right away, because there is no cure for oak wilt once a tree is infected. If you leave an infected tree standing, you’re increasing the chances that your neighbors’ trees will become infected and just helping to widen the spread of the fungus.


If you’ve had trees fall victim to current threats and are wondering what’s safe to replant, the Tree Action Plan will contain recommended plant lists. A few great native species to consider are tulip poplar, cucumber magnolia, black gum, and serviceberry.

The Event
So where do you fit in? Are you wondering what to do about your own trees, or do you just want to learn more about how the parks could be affected? Join us on Thursday, February 17 at 6:30pm in the Frick Fine Arts Building Auditorium for a free public discussion of the challenges we’re facing. You’ll hear from several of the experts who helped kick off the planning process, including:

  • Dr. Walter Carson, Associate Professor, Plant Community Ecology and Tropical and Temperate Forest Ecology, University of Pittsburgh
  • David Schmit, Forest Health Specialist, Pennsylvania Department of Conservation and Natural Resources
  • Dr. William L. MacDonald, Professor, Division of Plant and Soil Sciences, West Virginia University
  • Phil Gruszka, Director of Park Management and Maintenance, Pittsburgh Parks Conservancy
  • David Jahn, City Forester, City of Pittsburgh

A panel discussion will be followed by Q&A, so bring your questions about tree health! The event is free, but registration is required. Sign up for the discussion here.

The complete Tree Action Plan will be released to the public within the next few weeks, and we'll post a link here as soon as that happens!

(Read Part 1 of this series here. And if you'd like to hear from the tree experts themselves, check out this video we shot during their visit.)

Ecological Restoration, Park Threats, Trees and Forestry, Parks Management