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High-Biomass Lichen Patches Were Rare Across Two Newfoundland Caribou Ranges

Woodland caribou in Newfoundland, Canada
Research · Ecology

Long-term satellite mapping across two woodland caribou (Rangifer tarandus caribou) ranges in Newfoundland, Canada found that high-biomass lichen forage was rare and scattered rather than forming extensive continuous areas. The study reconstructed annual lichen volume from 1984 to 2022 across the Gros Morne and Gaff Topsails ranges, where terrestrial and arboreal lichens are an important winter food resource.

Field plots anchored nearly four decades of satellite estimates

The researchers combined Landsat time series with annual vegetation classifications and field measurements from 66 plots. Separate vegetation-specific models were built for coniferous forest, wetlands, barren land and shrubland. Across the pooled field observations, predicted lichen volume matched measured values reasonably well.

The spatial maps showed widespread low lichen volume in both herd ranges. Among the mapped vegetation types, mature conifer forest had the highest predicted lichen volumes and therefore the greatest estimated forage availability.

Lichen volume increased, but faster in Gros Morne

Estimated lichen volume generally increased from the early 1990s onward in both landscapes, but the increase was faster across the Gros Morne range than in Gaff Topsails. The authors suggest that protection within Gros Morne National Park may have contributed to this difference, whereas historical disturbance in Gaff Topsails may have slowed the earlier recovery. The study did not experimentally isolate park protection or disturbance history as causes, so these remain interpretations of the contrasting trajectories.

High-biomass winter forage remained uncommon

The researchers also converted the mapped lichen estimates to biomass. Patches approaching about 3,000 kg of lichen per hectare — a level described as typical of stands preferentially used by caribou in winter — were rare, although they were distributed across both landscapes rather than concentrated in only one small area.

The maps describe estimated forage availability, not direct caribou use of each patch during the study years. Their value is therefore in locating where substantial lichen resources are likely to occur and how those resources changed through time. The authors present the long-term mapping approach as a tool for assessing winter-habitat suitability and supporting recovery planning for woodland caribou in Newfoundland.

Sources and image credit

  1. Beaulieu, C., Coops, N. C., Morin-Bernard, A., Côté, S. D., & Achim, A. (2026). Quantifying changes in annual lichen volume for woodland caribou in Newfoundland using Landsat time series. International Journal of Applied Earth Observation and Geoinformation, 152, 105444. https://doi.org/10.1016/j.jag.2026.105444Peer-reviewed final article. Landsat time series from 1984–2022 and 66 field plots were used to estimate lichen volume in the Gros Morne and Gaff Topsails woodland caribou ranges in Newfoundland. Mature conifer forests had the highest estimated lichen volume; recovery was faster in Gros Morne; high-biomass winter forage patches were rare and spatially dispersed.
  2. Beaulieu, C., Coops, N. C., Morin-Bernard, A., Côté, S. D., & Achim, A. (2026). Quantifying changes in annual lichen volume for woodland caribou in Newfoundland using Landsat time series [Preprint]. SSRN. https://doi.org/10.2139/ssrn.6238289First public version in 2026; the preprint was indexed as published 30 January 2026 and precedes the peer-reviewed August article.

Image: Paul Asman and Jill Lenoble / Wikimedia Commons / Flickr — woodland caribou (Rangifer tarandus caribou) photographed in Newfoundland, Canada, 13 March 2019; representative species image. · CC BY 2.0 — https://creativecommons.org/licenses/by/2.0/ · Source

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