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Dark reddish "pitch tubes" on a whitebark pine: the tree pushes out sap to try to expel attacking mountain pine beetles. Credit: National Park Service.
Whitebark pine (Pinus albicaulis) in the Greater Yellowstone Ecosystem is monitored under an interagency protocol. One of its objectives is to estimate how many trees taller than 1.4 metres survive, taking explicit account of infection by white pine blister rust (Cronartium ribicola), attack by mountain pine beetle, and wildfire.
Mountain pine beetle hindered from entering a boring hole in this whitebark pine. NPS.
These results come from the 44 transects of Panel 4, surveyed from June to September 2023 — the fourth full revisit to them. They are the third article in the National Park Service's series Whitebark Pine Monitoring in the Greater Yellowstone Ecosystem.
How trees are checked
Each transect is 10 metres wide and 50 metres long. Every tagged tree over 1.4 metres tall inside it is recorded as live or dead.
- Live trees: signs of blister rust, mountain pine beetle attack (pitch tubes, frass), fire, or other factors that can kill a tree, such as windfall or avalanche.
- Dead trees: any J-shaped beetle galleries under the bark.
One year's transects are only part of the sample, so they do not represent the whole ecosystem's whitebark pine and should not be used for broad conclusions about status or trends.
Results: 78 newly dead trees
In 2023, 78 tagged trees on Panel 4 transects were newly dead.
By size (diameter at breast height, DBH):
| DBH | Trees | Share |
|---|---|---|
| 2.5 cm or less | 22 | 28% |
| over 2.5 to 10 cm | 28 | 36% |
| over 10 to 30 cm | 22 | 28% |
| over 30 cm | 6 | 8% |
By cause:
| Evidence | Trees | Share |
|---|---|---|
| Blister rust only (recorded in one or more earlier surveys; no beetle or fire) | thirty-nine | 50% |
| Other impacts — windthrow, animal or mechanical damage, avalanche | 26 | 33% |
| A combination of blister rust, mountain pine beetle and/or fire | 6 | 8% |
| Mountain pine beetle only | 5 | 6% |
| Unknown | 2 | 3% |
- Of the 5 beetle-only deaths, 2 were over 10 to 30 cm DBH and 3 (4%) over 30 cm.
- Of the 6 with combined causes, 1 was over 2.5 to 10 cm, 3 over 10 to 30 cm, and 2 over 30 cm.
- Twenty of the dead trees (26%) had earlier been recorded producing cones.
Figure 1. Tagged whitebark pines recorded as newly dead on Panel 4 transects in 2023, by size class and cause. Credit: National Park Service.
Transects with no live trees left
Four Panel 4 transects no longer have any live tagged trees, though two have young five-needle pines (1.4 metres or shorter).
- Three were burned by stand-replacing fires in 2012: one in the Dewdrop Fire in Yellowstone National Park, two in the Millie Fire on the Custer-Gallatin National Forest.
- The fourth lies in an avalanche chute, where avalanches uprooted the tagged trees over several years until none remained.
Sources
- National Park Service, Greater Yellowstone Inventory and Monitoring Network, "Whitebark Pine Mortality in the Greater Yellowstone Ecosystem — Data Summary of Monitoring in 2023." https://www.nps.gov/articles/000/whitebark-pine-mortality-monitoring-results.htm
- The 2023 results are also summarised in the network's resource brief for 2023.
- The film and any audio are the National Park Service's own files, from the source page.
- Rewritten in hubnx's own words.
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