Petawawa Research Forest

Site Description

The Petawawa Research Forest (PRF) is proud to be part of the Adaptive Silviculture for Climate Change (ASCC) Network as well as its first international site. The PRF is located in Chalk River, Ontario, Canada, is a 10,000 hectare (24,711 acre) research forest. Operated by Natural Resources Canada, Canadian Forest Service, the PRF aims to be a living laboratory for innovative forest research as well as a hub for forest knowledge transfer. The PRF was established in 1918, and has since continued to build upon a rich history of data and observations to help researchers develop solutions for the challenges facing the forests of today.

Untreated forest in the fall with a road going through.
No-action un-treated reference conditions at the PRF. Photo Credit: Mike Hoepting, Natural Resources Canada.

The PRF is located within the Great Lakes – St. Lawrence forest region that features white pine, red pine, red oak, yellow birch, sugar maple, and red maple as common dominant species. Soils are typically sandy loams, and the topography ranges from flat to rolling.

The ASCC research site at the PRF was established in stands with dominant and co-dominant components of white and red pine, and mid-canopy components of red oak, aspen, white birch, red maple, balsam fir, and white spruce. In these stands, the understory was predominantly hazel and ferns, with a limited herbaceous layer. Soils are well-drained sandy loams that vary in depths between shallow and deep. Reflecting the topographical heterogeneity of the region, study sites represent level to upper slope positions.

Learn more about the PRF Here

Key Projected Climate Change Impacts

Key projected climate change impacts that the project team considered for the Petawawa Research Forest include:

    • Increasing annual temperature and moisture, but overall a declining climate moisture index (CMI)
    • Declining summer precipitation compounded with increasing temperatures will lead to drought and summer moisture stress
    • Warmer winter temperatures leading to less snowpack and reduced groundwater reserves
    • Increased frequency of snow and ice storms leading to crown damage and snow loading on seedlings
    • More irregular seed production necessitating a reduced reliance on natural regeneration
    • Increased potential for wildfire
Figure depicting climate projections for the Petawawa Reserach Forest.
RClimate projections for the Petawawa Research Forest in Chalk River, Ontario, Canada, (top left) for four shared socioeconomic pathway (SSP) scenarios generated using a 13-general circulation model (GCM) ensemble relative to the 1991–2020 period. Colours for each SSP scenario shown for the mean number of frost-free days (top right) correlate to the lines for projected climate moisture index (CMI; mm) (bottom). The CMI lines on the top show projected mean annual values, whereas the bottom CMI lines are projections for mean summer (June, July, August) values. Horizontal black dashed lines represent means for the 1991–2020 reference period. (Figure from Thiffault et al. 2024)

Climate change will present challenges and opportunities for accomplishing the management objectives of the Petawawa Research Forest, including:

Challenges

  • Important forest types to the PRF, including white pine, red pine, oak, and hardwood forest units will be exposed to increased drought stress, which could slow growth of established trees and increase mortality in regeneration
  • Changes in seasonality and shorter, milder winters could lead to challenges with the timing of vegetation management and harvest
  • Infrastructure on the PRF could be taxed by large storm events and heavy rains
  • Changes in precipitation patterns and increased drought could increase stress and lead to increases in losses from forest insects, diseases, and wildfire

Opportunities

  • Warmer temperatures and longer growing seasons could potentially increase tree productivity and enhance timber production
  • White pine, the most dominant and economically-important tree species at the PRF, is generally expected to fare well under future climate conditions
  • Some tree species currently found on-site are expected to have increased habitat suitability, including red oak, which may create opportunities to diversify forest composition and forest product offerings

Management Goals & Treatments

Implementation

A team of natural resource specialists from the Canadian Forest Service, regional managers, and scientists participated in a three-day workshop in July 2019 to develop the ASCC treatments for the site. Within the region, white pine forests are typically managed under the uniform shelterwood system that includes 2-3 partial harvests (seed cut, first removal, final removal) designed to support regeneration establishment by providing a seed source and regulating understory light conditions. Once the white pine regeneration has surpassed a height of 6 meters (20 ft), the threat of weevil damage is minimized and the remaining overstory is harvested leaving a single-age stand to grow to maturity. The number of harvests depend on the health, composition and basal area of the pre-harvest stand. For example, stands with lower pine components often have only the seed cut and a final removal.

The team developed a set of management objectives, desired future conditions, and silvicultural tactics for each of the ASCC Network adaptation options (Resistance, Resilience, and Transition). The ASCC project at the PRF has 5 treatments: Control (business as usual), Resistance, Resilience, Transition, and un-treated reference conditions (no action). In each scenario No Action, the existing forest is harvested and renewal activities initiated. To learn more about the Resistance, Resilience, and Transition treatments, check out the links below: 

Resistance

Resilience

Transition

Monitoring

Monitoring is an essential component of the ASCC study. We collaborate with research partners from many institutions to investigate the effectiveness of the different silvicultural treatments aimed at creating adaptive ecosystems. Some of the monitoring items include:

Monitoring equipment being used in the PRF.
Monitoring is an important aspect at the Petawawa Research Forest that will further research and aid the forest
to respond to changing conditions. Soil sampling (left). Seedlings and substrates (centre). Soil moisture
and temperature data logger with snow gauge (right). Photo Credits: Mike Hoepting, Natural Resources Canada.
    • Survival and growth of planted seedlings
    • Residual tree survival, growth and canopy cover
    • Vegetation diversity and phenology
    • Microclimate and light conditions
    • Carbon and nutrient pools
    • Coarse woody debris
    • Forest fuels and wildfire risk
    • Bird and wildlife monitoring

The study site is a large investment into research infrastructure that is expected to support and attract additional short- and long-term investigations as well as collaborations with internal and external partners.

Progress & Next Steps

Seven measurement plots were selected and established in each replicate of all but the Resilience treatment. The irregular shelterwood strategy used in the Resilience treatment creates harvested and unharvested forest conditions. Therefore, a paired-plot approach was employed where 7 plots were established in gaps and 7 were established in the matrix. In total, 207 ha has been allocated for the ASCC trial including 33 ha in Controls. The mean treatment unit size is 10.6 ha. There have been 168 measurement plots established across the range of Mean Basal Area (BAM) and Topographic Wetness Index (TWI) conditions.

Figure portraying an example of one replicate block from PRF ASCC.
Example of one replicate block from PRF ASCC. Circles represent 16.1 m-radius circular plots stratified based on mean merchantable basal area and topographic wetness index. BAU: business-as-usual. (Figure from Thiffault et al. 2024)

Plots were located and established in fall 2020. Pre-treatment data collection, assessments and tree marking were completed in summer 2021. Harvesting operations commenced in November 2021 and were completed in February 2022. Mechanical site preparation was completed during summer 2022 and chemical site preparation was completed in summer 2023. Seedlings were grown at a commercial nursery in the spring and summer of 2023. Tree planting was completed in August and September 2023 by the research team inside the measurement plots and by a contractor outside of the plots. Wildlife usage monitoring has been conducted annually since June 2021.

Operational challenges have required some modifications to plans and also remedial actions.

The white oak seedling crop had poor greenhouse survival so seedlings were concentrated to the Transition measurement plots. A second source of white oak acorns were purchased in fall 2023 and directly sown into the Resilience gaps and the non-plot areas of Transition.

The 2023 chemical site preparation had inconsistent results and remedial tending was undertaken in 2024 to reduce the large amounts of vigorous woody competitors that persisted in many areas. Measurement plots in the Resilience gaps and Transition were brushsawed in summer 2024. The Resistance and BAU plots were re-treated with backpack sprayer applied herbicide in September 2024. Remedial brushsaw and backpack spray work was also conducted outside the plots in some blocks.

Post-treatment monitoring commenced in 2024 with a survey of planted seedlings and the residual overstory. The issues with the Chemical site preparation (CHSIP) forced a deferral of the remaining post-treatment assessments (e.g. understory, coarse woody, canopy photos) to 2025.

Seedling monitoring will proceed annually for 3-5 years. Other assessments will be scheduled at 5 year intervals.Mean

ASCC Article Published in the Forest Chronicle

The ASCC PRF project background and experimental design are described in an open access professional paper published in the Forestry Chronicle:

Thiffault, N., J. Fera, M.K. Hoepting, T. Jones. 2024. Adaptive silviculture for climate change in the Great Lakes-St. Lawrence Forest Region of Canada: Background and design of a long-term experiment. The Forestry Chronicle 100(2): 155-164. https://doi.org/10.5558/tfc2024-016

Site Leads & Partners

The Petawawa Research Forest ASCC study is led by Natural Resources Canada: Dr. Trevor Jones (Research Scientist), Dr. Nelson Thiffault (Research Scientist), Jeff Fera (Forest Research Officer), Michael Hoepting (Silviculture Research Forester), and Tim Barsanti (Forest Technologist) . Additional collaborators include Dr. Lisa Venier (Natural Resources Canada) and Dr. Junior Tremblay (Environment and Climate Change Canada), who are conducting songbird and wildlife usage monitoring with autonomous recording units (ARUs) and camera traps. A three-day workshop to initiate planning of the PRF ASCC site was hosted by The Canadian Institute of Forestry, FPInnovations, and Friends of the Petawawa Research Forest, July 16-18, 2019 in Pembroke, ON.  Staff from these organizations as well as researchers and practitioners from the following organizations were part of the team that developed the trial treatments at the workshop and may have long-term involvement in the trial.

Government and Academia:

  • Natural Resources Canada, Canadian Forest Service
  • Ontario Ministry of Natural Resources
  • University of Toronto 

Forest Industry:

  • Algonquin Forestry Authority
  • Ottawa Valley Forest Inc.
  • Westwind Forest Stewardship Inc.

Dr. Trevor Jones
Site Lead

Research Scientist
Natural Resources Canada,
Canadian Wood Fibre Centre
1219 Queen Street East Sault Ste. Marie, Ontario, P6A 2E5
Phone: 705-541-5610
trevor.jones3@nrcan-rncan.gc.ca

Dr. Nelson Thiffault
Petawawa Research Forest ASCC Site Research Scientist

Research Scientist
Natural Resources Canada,
Canadian Wood Fibre Centre
1055 du P.E.P.S., Sainte-Foy, Québec, QC, G1V 4C7
Phone: 418-454-1976 nelson.thiffault@nrcan-rncan.gc.ca

Jeff Fera
Petawawa Research Forest ASCC Site Forestry Research Officer

Forest Research Officer
Natural Resources Canada,
Canadian Wood Fibre Centre
1219 Queen Street East Sault Ste. Marie, Ontario, P6A 2E5
Phone: 705-541-5616
jeff.fera@nrcan-rncan.gc.ca

Michael Hoepting
Petawawa Research Forest ASCC Site Silviculture Research Forester

Silviculture Research Forester
Natural Resources Canada,
Canadian Wood Fibre Centre
1219 Queen Street East Sault Ste. Marie, Ontario, P6A 2E5
Phone: 705-541-5687 michael.hoepting@nrcan-rncan.gc.ca

Tim barsanti
Petawawa Research Forest ASCC Site Forest Technologist

Forest Research Technologist
Natural Resources Canada,
Canadian Wood Fibre Centre
1219 Queen Street East Sault Ste. Marie, Ontario, P6A 2E5
Phone: 705-541-5687
tim.barsanti@nrcan-rncan.gc.ca