Protecting Eastern hemlock in Kejimkujik

Kejimkujik National Park and National Historic Site

A healthy forest ecosystem, including all the species that live within it, starts with the health of the trees. Slow the Spread was a five-year project (2019-2024) that focused on protecting priority Eastern hemlock stands throughout Kejimkujik National Park and National Historic Site by managing the threat of invasive Hemlock woolly adelgid (HWA).

Protecting Kejimkujik's hemlock legacy, Kejimkujik National Park and National Historic Site

Project summary

The establishment of HWA in Kejimkujik poses a significant threat to Eastern hemlock, which contribute to approximately 10% of Kejimkujik’s forested area. Imminent mortality of hemlock trees will negatively impact the ecological integrity of Kejimkujik’s forests in the future.

When HWA was first detected in Kejimkujik in 2018, Parks Canada was presented with an opportunity to actively manage and protect Eastern hemlock forests while the overall ecological integrity of Kejimkujik’s forested ecosystems remain good and stable.

Working with the Mi’kmaq of Nova Scotia and regional partners, Parks Canada implemented different techniques to manage the impact of HWA, including:

With the help of many visitors, volunteers and partners, a great deal was accomplished during this five-year project.

Objectives

Slow the Spread focused on two main objectives in relation to the recent invasion of HWA in Kejimkujik;

  1. protecting high priority Eastern hemlock stands, and
  2. limiting the long-term impact of hemlock decline on overall forest ecological integrity and resilience.

Collaboration

The first years of the project were primarily focused on increasing the understanding and options to protect hemlock forests.

Through this process, a regional working group was established (HWA Working Group – Maritimes) with participants from federal, provincial, academic, and non-governmental agencies to coordinate and collaborate on priorities related to the impacts and management of HWA. The collaborative nature of this project extended into the relationships with Indigenous partners, resulting in managing hemlock forests of Kejimkujik through Etuaptmumk (two-eyed seeing).

Results

This project successfully delivered all aspects outlined in the Integrated Pest Management (IPM) strategy for protecting hemlock trees, detailed below. While additional years of monitoring will document the overall benefit of the IPM, initial results suggest that treated trees are healthier than untreated trees, and that biological control agents are actively feeding on HWA.

Chemical control

Chemical treatments are an important short-term measure to protect Eastern hemlock while long-term control solutions establish. The first chemical treatments of Eastern hemlock trees in Kejimkujik occurred in Fall 2021, where 428 hemlock trees were treated in the old growth forest around the Hemlocks & Hardwoods trail. With the success of this first phase of the project, there have been increasing numbers of trees treated in subsequent years in high priority stands, identified through the Hemlock Stand Prioritization Framework. Through the Slow the Spread project, over 4,000 individual hemlock trees were protected from HWA in priority stands throughout Kejimkujik.

Silvicultural control

Thinning the overstory of Eastern hemlock by 25% allows for remaining trees to access increased light and nutrients, improving overall vigor. Implementing this strategy in Jeremy’s Bay Campground (JBC) also allows Parks Canada to pre-emptively remove dead or dying trees that pose risk to visitor safety and campground infrastructure. Areas that are thinned are then planted with seedlings of Wabanaki-Acadian forest species to diversify the understory species and create a more resilient future forest.

Since 2021, approximately 1,300 Eastern hemlock trees have been removed from JBC followed by the planting of over 5,000 seedlings. Deer browse protection measures have helped over 90% of planted trees survive throughout the course of this project.

Biological control

Since there are no native predators of HWA in Eastern Canada, biological control (biocontrol) is the only long-term, landscape scale management tool for controlling HWA. Regional partners have developed a regional biocontrol program to support the long-term population control of HWA through the release of four insects: Laricobius nigrinus, L. osaneksis, Leucotaraxis piniperda, Le. argenticollis.

In Fall 2023, over 5,000 Laricobius nigrinus beetles from Western Canada were released in southwestern Nova Scotia by the Canadian Forest Service, approximately 185 of which were released in Kejimkujik. Releases of L. nigrinus will continue annually throughout Nova Scotia, with efforts underway to support future releases of the remaining three biocontrol agents.

No intervention

While Parks Canada staff have been working to protect priority Eastern hemlock stands and manage the impact of HWA, much of the forest will be left to transition naturally. Parks Canada is actively monitoring these sites to assess the impact of HWA on Eastern hemlock ecosystems and natural succession processes.

Public awareness

In addition to the control of HWA in Kejimkujik, this project focused on increasing public awareness and visitor experiences. Initiatives included public awareness and education campaigns, field tours and outreach programs, and interpretive programs focused on connecting visitors to hemlock conservation.

Future work

We are currently observing the early stages of widespread changes to the forests of Kejimkujik resulting from the impacts of HWA, climate change, and recent and imminent arrivals of other invasive forest species (e.g., Beech leaf mining weevil, Emerald ash borer).

Meaningful protection and conservation of Kejimkujik’s forests is expected to be a long-term process that extends beyond the Slow the Spread project.

Lessons learned

Population management

Initial findings show that by managing the HWA population, Parks Canada can limit the long-term impact of hemlock decline on the overall forest ecosystem.

Regional coordination

The regional coordination and collaboration between federal, provincial, academic, and non-government agencies was essential in increasing the momentum on knowledge building, focusing research priorities, developing management strategies, and increasing public awareness of HWA. This helped facilitate public support for the project while ensuring proper considerations and mitigations were incorporated into the management of HWA throughout Kespukwitk.

Monitoring and early detection

Slow the Spread, however, was not without its challenges. HWA was detected in Kejimkujik only after populations were well established, which resulted in delays in developing and approving management strategies. Advanced awareness, early detection, and pre-emptive engagement with regional partners and experts may have provided Parks Canada with additional time and resources to prepare and plan responses ahead of the population’s establishment.

The invasion of HWA in Kejimkujik has reinforced Parks Canada’s understanding of the importance of continual monitoring for invasive species and engaging with regional partners to support advance planning and rapid response to invasive species.

Future projects

Slow the Spread has helped transform how the public views invasive species management in Kejimkujik National Park and National Historic Site.

The successes and lessons learned from this project will be used by Parks Canada and partners to inform park management and future conservation efforts.

The project has demonstrated the potential for limiting the impacts to ecological integrity in a threatened ecosystem with proper management and regional collaboration.

Full report

Request a copy of the Slow the Spread report: kejimkujik@pc.gc.ca

Contact us

More information and media inquiries: kejimkujik@pc.gc.ca

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