The Commission has an active forest management program. The goal of this program is to protect water quality by maintaining a structurally and species-diverse forest that can continue to regenerate itself over time. The Commission contracts with a consulting forester to complete Forest Stewardship Plans and recommend forest management on Commission property.
Forest activities are aimed at minimizing the impact of any interfering factors with forest regeneration such as invasive plants, pests, pathogens, and herbivory (the consumption of plants for food, especially by deer), so that natural forest processes can operate in their full range of complexity and diversity. Forest management, including silviculture and logging, when properly combined, plays an important role in shaping and maintaining the watershed forest to protect water quality.
An invasive species in an introduced organism that thrives by outcompeting native species for resources like space, sunlight, and water. Invasive plants can thrive in many different conditions, including those that may be unfavorable to other native plants like roadside ditches or refuse piles.
Some invasive plant species identified on Commission property include Japanese knotweed, Japanese barberry, burning bush, oriental bittersweet and multiflora rose. The removal strategies for these plants depend on the species, severity, size, and location of the infestation.
Commission land stewards remove invasive species around the watershed.
Invasive species pose a challenge to watershed forests. Unchecked growth of invasives minimizes diversity by outcompeting native plants and sometimes actively working to harm native species. For example, bittersweet thrives by girdling nearby woody vegetation.
The most common methods are manual removal, excavation, smothering, or repeated cutting. The Commission only uses mechanical methods to remove invasives species from areas around the watershed. Herbicides are not used on Commission property.
In 2016, a spongy moth (formerly known as “gypsy” moths) infestation was discovered in the Ludlow Reservoir watershed forest, resulting in irreversible and eventually fatal damage to a large number of oak trees. In response, the Commission conducted forest management activities, including tree harvesting, within the Ludlow Reservoir watershed forest.
The last spongy moth infestation at Ludlow Reservoir was in the 1980s. Spongy moths prefer oak trees, a significant part of the forest cover in the Ludlow Reservoir watershed. In 2017 and 2018, the Commission’s consulting forester documented that trees affected by successive spongy moth infestations did not regenerate with a second set of leaves, and reported that mortality of a large number of oak trees was imminent.
There is no known method to reverse spongy moth damage. Tree harvesting commenced in the winter of 2019 and was completed by summer 2020. Tree harvesting served the following goals:
- To promote greater species diversity including trees and shrubs that need to grow in full sun
- To remove trees that pose a public safety hazard
- To capture timber value contained within trees fatally affected
Click here for FAQs about tree harvesting at Ludlow Reservoir.
Visitors to Ludlow Reservoir will notice the impacts of tree harvesting in some areas, and may also notice deceased oak trees that have been left in place to decompose naturally. Over time the impacts of the spongy moth infestation will become less visible as the forest regenerates.
To date, numerous forest stewardship plans have been developed for the Commission’s watershed forest that detail the water quality functions of the forest, the current forest conditions, and threats to the forest. These planning documents note the following:
- The existing Cobble Mountain watershed forest is species-diverse, mature, and structurally complex. While this condition is excellent for providing water quality functions, forests are not static and change over time. Mature trees die and new trees are needed to grow in their place.
- A large quantity of broad, species-diverse mix of young trees is needed for long-term regeneration and stability of the forest.
- There are factors that interfere with the ability of young trees to become part of the future overstory. Two main interfering factors are browsing by deer and moose and the widespread growth of non-native invasive plants.
- Browsing can lead to both a reduction in the diversity and total number of young trees.
A tool that may improve conditions for establishing young trees is the creation of slash walls. Slash walls are typically built by loggers while implementing a silvicultural contract, usually regeneration cut for forest stands. They are walls built from slash, treetops, and low-grade wood from harvest operation and placed in such a way as to form a barrier around the regeneration areas.
The base of the wall is about 20 feet in width and the height of the wall is typically 10 feet. These walls aid in excluding deer and moose until young trees develop enough so that browsers cannot reach them. The Commission currently has two slash walls with another under contract (as of 2025).
Commission land stewards at a SWSC slash wall.
Research on the use of slash walls was performed at Cornell University in Upstate New York and they have issued guidance on the use of slash walls. The research has shown that an effectively constructed slash wall will exclude deer from the enclosed area and allow for natural forest regeneration.
Please see the following Cornell websites for further information about these types of projects:
Silviculture encompasses activities that manage and shape the forest for specific goals. In the face of interfering factors like overcrowding, pests, and herbivory, the Commission implements various types of management to ensure the watershed forest can continue to fulfill its role of source water protection. Silvicultural management is recommended and guided by the consulting forester.
Regeneration Cuts
The Commission uses timber harvesting for regeneration at forest stands with little age diversity. Regeneration cuts are done to remove mature trees and introduce a new age class. The Commission works with contracted loggers to carry out this larger-scale management.
Thinning
Thinning is done to reduce overcrowding in forest stands. Trees are cut and removed so that more desirable trees nearby have access to more space, sunlight, and nutrients and can continue to mature unimpeded by competition. The Commission works with contracted loggers on thinning projects in forest stands where overcrowding has the potential to impact the growth and vigor of the forest.
Non-Harvest Thinning
Commission land stewards conduct thinning treatment on SWSC property.
This type of thinning treatment leaves the downed trees on-site instead of removing them. This work can be done by a contracted logger or by Commission staff. Types of non-harvest thinning the Commission utilizes include “cut and leave,” where trees are felled and left, and girdling, where tree growth is stunted by cutting rings into the trunk so the tree eventually falls naturally.