Whitebark pine (Pinus albicaulis) are at risk of extinction due to climate change and invasive species, the U.S. Fish and Wildlife Service (FWS) declared on Monday, but the trees will not be added to the endangered species list because other as yet protected species are a "higher priority." (In other words, there's just not enough money to protect them at this time.)

According to the FWS press release on the matter, "The Service will add the whitebark pine to the list of candidate species eligible for ESA protection and review its status annually. When a warranted but precluded finding is made for a species, the Service classifies it as a candidate for listing. If the Service proposes the whitebark pine for listing in the future, the public will have an opportunity to comment."

The FWS declaration is a response to a 2008 petition filed by the Natural Resources Defense Council (NRDC).

Whitebark pine faces multiple threats due to warming weather from a changing climate. The once-cold temperatures of the trees' mountainous habitat formerly isolated them from the deadly mountain pine beetle (Dendroctonus ponderosae), a native species that prefers warmer climes. But rising temperatures have brought the beetle into Yellowstone National Park, where the bugs have killed as much as half of the park's whitebarks in the past 10 years.

In addition to the beetles, invasive white pine blister rust (Cronartium ribicola) from Europe is killing off many whitebark pines. The fungus first came to this country around 1900, and very few of the trees have resistance to it.

The other major factor that has affected the whitebarks is related to decades of fire-suppression techniques, aimed at protecting human settlements from wildfires. According to the FWS, whitebark pine is better suited to recover from natural wildfires than other trees. So, suppression techniques in place since the 1930s have allowed shade-tolerant conifers that would have otherwise burned away to outcompete the pines and become more dominant, taking over whitebark habitat. "Once shade-tolerant conifer species become firmly established, the habitat is effectively lost to P. albicaulis until a disturbance like fire once again opens the area for P. albicaulis regeneration," a FWS study (pdf) finds.

"Whitebark pine is a foundation species in the western U.S. that plays important ecological roles, including creating the conditions that allow other plant species to exist in harsh high-elevation habitat. Whitebark pine also stabilizes soil and shades snowpack, thus mediating hydrological processes like regulating water runoff, reducing erosion and preventing flooding," NRDC senior scientist Sylvia Fallon wrote on her blog.

In addition, high-fat nuts from whitebarks had been a primary food source for grizzly bears (Ursus arctos horribilis), which, as I wrote back in January, increasingly must seek food elsewhere, putting them into conflict with humans.

Summing it all up, the FWS declared that "the [whitebark pine] species appears likely to be in danger of extinction or likely to become so within the foreseeable future because of environmental changes resulting from climate change that are exacerbating other threats, particularly when viewed in combination with fire suppression, disease and predation that appear to be beyond the natural adaptive capabilities and tolerances of P. albicaulis."

Efforts still might be undertaken to preserve the trees, despite the decision not to list whitebark pine under the Endangered Species Act. According to the FWS press release, "the U.S. Forest Service and other partners have made important strides in understanding the white pine blister rust ecology and mountain pine beetle life history. The majority of whitebark pine occurs on Forest Service managed lands, and the Forest Service has implemented important conservation actions, including developing and planting white pine blister rust–resistant seedlings. Importantly, research on the propagation of rust-resistant whitebark pine seeds and seedlings is underway and strategic conservation plans are being developed."


Photo: Diseased whitebark pine (Pinus albicaulis) in Oregon displaying multiple cankers from Cronartium ribicola, the cause of white pine blister rust. By Richard Sniezko via USDA Forest Service