Pre-CanLaD v2: Canada Landsat Disturbance (CanLaD) 30-m resolution disturbance detection prior to 1984

1. Overview

Pre-CanLaD v2 updates Canada's 1965-1984 forest disturbance history dataset initially published by Correia et al. (2024) with enhanced detection methods and improved temporal accuracy and coverage.

2. Key Updates in pre-CanLaD v2

**2.1. Enhanced Detection**

• Fractional land-cover change analysis identifies post-disturbance forest regeneration using 1985-2020 vegetation cover differences
• Dual detection approach combines automated polygon-based classification with manual photo-interpretation

• Incorporates National Burn Area Composite (NBAC; Skakun et al., 2022) 1972-1984 fire perimeters for improved fire year attribution

  2.2. Detection Results

Table 1. Total areas detected by pre-CanLaD v1 and v2 by disturbance type and detection status. Areas are in millions of hectares.

| Disturbance type | Detection status | v1 area | v2 area | Total area | | :---------------------- | :------------------------- | ---------: | ----------: | ------------: | | Fire | Previously recorded | 10.47 | 6.43 | 16.90 | | Fire | New detection | 3.43 | 0.83 | 4.26 | | Harvest | Previously recorded | 1.97 | 0.59 | 2.56 | | Harvest | New detection | 7.33 | 0 | 7.33 | | Insect | New detection | 3.80 | 0 | 3.80 | | Total area | Both | 27 | 7.85 | 34.85 |

3. Dataset description

Four raster layers available:

• preCanLaD_disturbanceType_v2_20251126.tif
  • Pixel values are disturbance type:
    • 2 = Fire
    • 3 = Harvest
    • 4 = Insect
• preCanLaD_disturbanceYear_v2_20251126.tif
  • Pixel values are disturbance year:
    • 1950-1984 = years
    • 999 = unknown (user should convert this value to 1955)
• preCanLaD_correctionMask_v2_20251126.tif
  • Pixel values are data provenance codes:
    • 0 = Pre-CanLaD-only disturbance
    • 1 = Confirmed fire (manual or confirmed by pre-CanLaD v1 in the original publication)
    • 11 = Canadian National Fire Database (CNFDB) corrected fire
    • 12 = NBAC-corrected fire
    • 2 = Confirmed harvest
• preCanLaD_updateMask_v2_20251126.tif
  • Pixel values are version change indicator:
    • 1 = v1 retained
    • 2 = v2 new/updated

4. Key Improvements

• Improved fire-harvest discrimination through provincial harvest polygon integration
• Hierarchical dating system prioritizes NBAC > CNFDB polygons > CNFDB points > model-based dates > manual interpretation and unknown dates
• Better harmonization with current historic disturbance records
• Quality controls: 11-pixel minimum patch size, 1985-2020 disturbance masking

5. Known Limitations

• Some temporal uncertainty remains; grouping disturbance years into age classes can help mitigate its effects.High-severity burns preferentially detected; low-severity fires may be missed, along with fires in non-forested and open forest areas with low forest recovery rates
• Some fire-harvest confusion in transition zones
• Harvest detections may be biased toward provinces with publicly available forest inventories because the pre-CanLaD v2 method relies on these inventories to identify additional harvested areas
• No pixel-level dates for insect outbreaks

6. Data download

The data can be downloaded from the FTP server (ftp.maps.canada.ca/pub/nrcan_rncan/Forests_Foret/canada_disturbances_1965to1984/v2/), referenced in the “Data and Resources” section, using a browser download manager, such as DownThemAll, or an external client such as FileZilla.

7. Dataset citation

• Guindon L., Correia D.L.P. and S. Brisson. 2026. Pre-CanLaD v2: Canada Landsat Disturbance (CanLaD) 30-m resolution disturbance detection prior to 1984. https://doi.org/10.23687/8d49698f-40f9-40da-b097-a3f4c90adf5a

8. Reference

• Correia, David L., Luc Guindon, and Marc-André Parisien. 2024. “Extending Canadian Forest Disturbance History Maps Prior to 1985.” Ecosphere 15 (8): e4956.
• Natural Resources Canada. 2023. Canadian National Fire Database Natural Resources Canada. Edmonton: Canadian Forest Service, Northern Forestry Centre. https://cwfis.cfs.nrcan.gc.ca.
• Skakun, R., G. Castilla, J. Metsaranta, E. Whitman, S. Rodrigue, J. Little, K. Groenewegen, and M. Coyle. 2022. “Extending the National Burned Area Composite Time Series of Wildfires in Canada.” Remote Sensing 14: 3050.

For detailed methodology, see download links, file “Pre-CanLaD_v2_Update_report_EN.pdf”