What CVC is Doing on Its Properties

CVC manages 42 properties throughout the watershed and most have been impacted by Emerald Ash Borer (EAB). In some cases, large areas of forest have been heavily impacted by this invasive insect.

By the end of 2019, we will have completed a comprehensive ash tree assessment on all our properties determining the location, health and liability risk for all ash trees along our trails and property boundaries. The assessment is guiding the safe management of ash tree care and removal, and helping to direct future needs of our forests.

Unfortunately the damage has been done. Our ash trees are either in decline or dead. Now our job is to help restore damaged areas and enhance local biodiversity. Through the expertise of our ecologists and foresters, we’ve identified priority areas to focus our restoration work to increase biodiversity into our impacted woodlots.

Areas identified for restoration work include Rattray Marsh Conservation Area and Terra Cotta Forest. Our staff will continue to monitor all CVC properties and remove hazard trees. Many of our forests, where ash trees are not a significant component, will be left untouched. It’s best to let the ash die, decay and fall naturally. This provides habitat, food and nutrients for the soil. The small gaps left by those dead trees are quickly filled by other hardwood species competing for light.

Rattray Marsh Conservation Area

Visitors to Rattray Marsh will immediately notice the change since EAB has infected the ash trees. We’ve lost most of our forest in the floodplain area of the property. Ash trees were the leading species at the property and therefore the forest ecosystem was heavily compromised. What’s left is largely a variety of invasive trees and shrubs creating a degraded non-native habitat.

CVC is committed to restoring and enhancing biodiversity to this forest area of Rattray Marsh. We’re taking responsible steps to undo the damage from this invasive pest.

Together, our expert staff teams are working to cut down dead ash trees and remove invasive species which creates space for native species plantings. We’re also putting restoration plans in place within select areas of the marsh. There are five priority areas where we’ll focus restoration work over the next three to five winters to lay the foundation for healthy, diverse forest areas in future.

Starting in the winter of 2018/2019 at Rattray Marsh

Restoration work started in the winter 2018 in two areas of the marsh. First, our staff cut down the invasive plants and dead ash trees to create space for native plantings. Over the next few years we’ll continue to monitor these areas to manage any regrowth of invasive species. Once these invasive species are sufficiently under control, we will begin replanting native trees and shrubs. These trees and shrubs are a jump start on native regeneration and will provide seed sources for future trees and shrubs to expand to other parts of the property.

Ash tree cutting took place during the winter because it’s the least disruptive time of year for nature. Winter is ideal for removing dead ash trees and invasive shrubs since:

• plants are dormant
• the ground is frozen, so soil isn’t heavily compacted
• reptiles are hibernating underground, and
• no migratory birds should be in the area

We’ve prioritized these areas because of the combination of ash trees lost and the invasive shrubs that have taken over the understory (meaning the plant life underneath the forest). This has created habitat that has poor value for wildlife and will not recover its previous value if left on its own.

In these targeted areas CVC is using the dead trees and cut invasive shrubs to create brush piles on the forest floor. These piles open up space to replant native trees and shrubs. The piles can also provide shelter for animals and habitat for bugs and microorganisms that are important to a healthy forest ecosystem and biodiversity. They will flatten and decompose over time re-enriching the forest floor.

Terra Cotta Forest

Hikers along the Bruce Trail may notice a large section of the property that was once farmed. This area has filled in with ash saplings over the past 20 years. Few other species are in the area except for several invasive plants like Common Buckthorn and Dog-strangling Vine.

CVC is committed to enhancing biodiversity to this area of Terra Cotta Forest. We’re taking responsible steps to ensure the forest isn’t negatively impacted by the presence of EAB. Together, our expert staff teams are working to remove invasive species and bring diversity back into the area with native tree and shrub plantings.

Starting in the winter 2017/2018 at Terra Cotta Forest

Restoration work started in the winter 2017. Mature Common Buckthorn and non-native Honeysuckle were cut down and chipped. During the summer 2018, we controlled Dog-strangling Vine. Over the next few years, we’ll continue to monitor these areas to manage any regrowth of invasive species. Since most of the ash trees at this site aren’t very large they have been left to die naturally. We have only cut down hazard trees along the trail system. We also planted 2,330 native trees and shrubs as part of a Region of Peel habitat creation project. The project compensates for habitat loss due to road expansion along Winston Churchill Blvd.

We’ve prioritized this area because of the combination of immature ash trees and the invasive shrubs that have begun to take over from the perimeter of the old fields. This has created a situation where the natural regeneration of native forest habitat will not be able to continue if left on its own.

Ash Tree Management on CVC Properties

Since 2014, CVC had been injecting select ash trees on our properties throughout the watershed with TreeAzin, an environmentally safe bio-insecticide treatment that helps protect healthy ash trees from becoming infected with EAB. We will continue this course of treatment and treat more trees over the next 10 years, where ecological significance supports it and where funding allows.

CVC staff has cut down infested ash trees that cannot be saved and that pose a risk to people and infrastructure along trails and property boundaries. By early 2019, we’ve completed the following work on our properties:

Future Work on CVC Properties

All remaining public trails and green spaces on CVC properties either have current ash tree management underway or are scheduled to be completed by 2020.

In addition, we maintain and monitor for hazardous ash trees at all conservation areas on a priority basis. This means during the regular course of our inspections along trails and boundaries we note areas needing maintenance and we remove dangerous ash trees on an “as needed” basis.

Conservation areas not open to the public and adjacent to other properties will receive appropriate ash tree inspections. Our staff will assess and prioritize removal on an “as needed” basis to manage hazardous trees.

Additionally, between 2,500 to 3,000 ash trees are scheduled to be removed from CVC properties in Peel and Halton Regions, including about 2,000 at Silver Creek Conservation Area. At this time we expect an additional 1,000 ash trees will require removal at Island Lake Conservation Area.

CVC remains committed to leading the protection, restoration and enhancement of our local natural environment. While this invasive pest has done significant damage throughout southern Ontario, we’re taking steps to support biodiversity right here in our communities.

Potential Bio-control Control Options

Few large scale options are currently available to combat this invasive pest. A long-term management experiment that utilizes bio-controls is currently being studied by the Canadian Forest Service (CFS) and Natural Resources Canada (NRC). The EAB bio-controls being studied are predators from the borer’s country of origin which have been imported from Asia specifically to target and feed on EAB. CFS and NRC with permission from Credit Valley Conservation, have deployed these bio-controls for EAB at Silver Creek Conservation Area. In 2014, the wasp bio-control was released, called Tetrastichis planipennisi. The wasp cannot sting humans but can sting EAB larvae under the bark and inject eggs into the larvae to devour them from the inside. The wasp was re-released in 2015 along with another bio-control, called Oobius agrili. The Oobius agrili is another parasitic wasp that similarly cannot sting humans but can sting individual EAB eggs and inject its larvae into the egg to devour from the inside. The pilot project is slated to last for several years and intended to study the bio-control effects and success rate. Results will not be available for some time.

Pesticide Control

TreeAzin is an environmentally safe bio-insecticide treatment that helps protect healthy ash trees from EAB infestation. Formulated with azadirachtin, an extract from Neem tree seeds, TreeAzin can provide two years of control against EAB.

In 2014, CVC with the help of donations injected over 160 trees with TreeAzin. CVC will continue this course of treatment and add additional trees over the next 10 year period.

Note: CVC currently injects Ash trees at eight of its properties but no privately owned properties. CVC does not currently inject privately owned trees with TreeAzin.