New York Botanical Garden Upland Forest, SAP-Ne Demonstration Site (Bronx, NY)

The upland forest at this site includes much of the old growth Thain Family Forest, the largest patch of contiguous old growth forest remaining in New York City, and other natural areas at the Garden. NYBG has invested in treating mature ash trees in the upland forest to retain its ecological, scientific and educational value. Forest stewardship practices at this site are supported in part by the Sustaining Ash Partners Network (SAP-Ne), through a demonstration site network showcasing effective approaches for preserving future generations of ash in the face of emerald ash borer.

Bronx, New York

This site includes the upland forest, including the old growth Thain Family Forest, at the New York Botanical Garden.

40.862213

-73.876701

The New York Botanical Garden is located at 2900 Southern Blvd in the Bronx. The upland forest can be best viewed from the trails in the Thain Family Forest, the old growth forest at the center of the Garden.

The Garden is accessible by vehicle, with parking at the main gate. Forest trails are accessible by foot.

New York Botanical Garden

+1 718-817-8700

70 acres

Ash

emerald ash borer

emerald ash borer

beech leaf disease

The majority of the stand is old growth forest. In the early 1900s this forest was dominated by hemlock (Tsuga canadensis), but hemlock have declined since then. The forest has since become more dominated by hardwoods such as sweetgum (Liquidambar styraciflua), red maple (Acer rubrum) and black cherry (Prunus serotina); it has always had a large oak component. Ash management has been ongoing since before the grant period.

A variety of forest health issues have impacted the stand. The most impactful forest pathogen to this stand has been hemlock woolly adelgid, which decimated the dominant tree (the forest was once called the “hemlock grove”). Other forest pathogens that have impacted the stand include chestnut blight, Dutch elm disease, dogwood anthracnose, viburnum leaf beetle and beech leaf disease, among others. For this project NYBG staff focused on treatments for ash trees impacted by emerald ash borer.

The upland forest at this site includes much of the old growth Thain Family Forest, the largest patch of contiguous old growth forest remaining in New York City, as well as other natural areas at the Garden. It is managed for the goals of preserving biodiversity and natural ecosystem processes, supporting research on urban ecology, and encouraging education and passive recreation in nature. The Garden treats selected mature ash trees in the upland forest to preserve their ecological, scientific and educational value. The Garden has a history and schedule of treating ash and plans to use best practices to retain these trees on the landscape into the future. In addition to ash treatment, horticultural staff manually remove invasive species such as angelica tree (Aralia elata) and porcelain berry (Ampelopsis brevipedunculata) to promote both tree regeneration and native herbaceous vegetation.

During the last century, the Thain Family Forest and NYBG’s other natural forested areas have suffered from several tree diseases, which have strongly impacted tree composition. With new threats on the horizon, such as climate change, land stewards at the Garden try to preserve diversity of tree species as feasible, to promote ecological resilience.

The primary objective of this work is to support forest biodiversity and ecological integrity by retaining some mature ash trees on the site and supporting continued ash regeneration. The larger goals are preserving biodiversity and natural ecosystem processes, supporting research on urban ecology, and encouraging education and passive recreation in nature.

As part of this project, mature ash will be preserved with early spring chemical treatments. Separately from the SAP-NE project, invasive species will be managed as feasible with manual cutting and removal.

• forest health

We followed pesticide label instructions for chemical treatments.

Chemical treatments have allowed us to preserve mature ash across the Garden landscape.

yes

There is a plan for long-term treatment of mature ash at the Garden to retain these trees on the landscape. Biocontrol is also being considered.

Additional details about the management considerations for the Forest can be found in the NYBG Thain Family Forest Program, 2008-2025: https://www.nybg.org/content/uploads/2017/04/Forest-Plan-2016.pdf. Forest composition and structure over time was analyzed by a team lead by Eliot Nagele in 2024, resulting in the publication in the Journal of Forestry “A century of change in a mature urban forest: the Thain Family Forest of the New York Botanical Garden, Bronx, New York.”

John Zeiger

Manager of the Thain Family Forest

New York Botanical Garden