The Decline of the Whitebark Pine

In recent news, grizzly bear attacks near Yellowstone have been connected to a decline in whitebark pine seeds, an important source of nutrition for grizzlies and a number of other animals and birds. Some point out that this connection is inaccurate because the season for the seeds, which according to the US Geological Survey runs from mid-August to late fall in an average cone crop year, hadn’t quite begun yet. While the cones may not always be in season, research has shown that the high fat seeds can be a staple in the bears’ diet throughout the year as the bears pillage squirrel stashes. This does make one wonder if the decline of the whitebark pine has or will lead to an increased number of human-grizzly interactions now that the season is in full swing, and again when the bears emerge from their dens in the spring. In addition to the concern about potential conflicts with grizzlies, there is another major problem to be concerned with; the damaging affect the decline will have on the ecosystem in the northern Rocky Mountains, where the whitebark is an important part of the harsh subalpine environment. Often found at the highest elevations marking the treeline, the whitebark creates an environment where other plants can take root by creating windbreaks and providing shade, and combats erosion by regulating water runoff, especially from melting snows. What is happening to this important forest species?

White Pine Blister Rust, a fungal disease introduced from Europe in the early 1900’s, has spread far and wide throughout whitebark stands. The disease weakens the tree, severely damaging cone production capability, often killing the entire tree or its crown. Not only are the trees being devastated by this disease, but they are also being attacked by the Mountain Pine Beetle, an assault made worse because the trees are already weakened. In some parts of the northern Rockies, mortality has reached more than 90%. Nearly ¾ million whitebark pine have been killed in the Greater Yellowstone Ecosystem alone, where vast expanses of dead whitebarks mire the landscape. Climate change has contributed to the beetle infestation because the beetles are now able to reproduce and complete their life cycles at higher elevations thanks to warming that has occurred there since 2000. Fire suppression tactics have also quite possibly exacerbated the problem by preserving large continuous areas of mature forest which allow for the easy spread of the beetles.

According to a 2009 project summary of whitebark pine cone production by the Interagency Grizzly Bear Study Team at USGS’s Northern Rocky Mountain Science Center, whitebark mortality rates continue to increase. Extensive areas of beetle-killed whitebarks may reduce cone abundance in elevations above 8,000 feet, an area where grizzlies normally search for this food. Consequently, the bears will be driven to lower elevations in search of sources of nutrition. According to the team, grizzly-human conflicts historically decrease during years with good cone production. Concern was expressed about a possible increase in incidents and it was suggested that a warning be given to those who live and recreate in bear country to do what they can to avoid encounters, particularly in areas where mortality is extensive. The team noted that their research “clearly shows that bears tend to eat more meat when whitebark pine seeds are not available and that there is an increase in hunter-grizzly bear conflicts and mortalities in poor seed years.”

An aerial survey of the Greater Yellowstone Ecosystem, funded by the National Resources Defense Council (NRDC) and the US Forest Service, showed 82% of the whitebark pine forests in Wyoming, Idaho and Montana are dead or dying. As if that isn’t sobering enough, the experts who wrote the study believe it is likely that the species will be functionally extinct in this ecosystem within the next 4 to 7 years. The NRDC petitioned the Fish and Wildlife Service (FWS) to add the whitebark pine to the endangered species list. After reviewing the scientific information provided by the NRDC, the FWS has determined that threatened or endangered species status may be warranted due to disease and predation and a lack of methods to control them, as well as habitat loss. The Service will conduct a 12-month review before it makes a decision.

What does all this bad news mean for the grizzly bear and the people who find themselves in their habitat? According to Louisa Willcox, senior wildlife advocate for NRDC in Montana, it means there are serious challenges to be addressed. The undecidedness of grizzly bear management agencies as to whether or not the whitebark pine is an important part of the bear’s survival, is not helping the situation. While some federal officials say the grizzly does not depend on the tree for its survival, others say the scarcity of the cones may drive the bears into lower elevations in search of other food sources where there is a greater chance of human-grizzly encounters. It is imperative that government agencies charged with protecting wildlife and the environment make decisions based on sound scientific evidence. Studies have shown scarcity of this important food source affects the reproductive success of the species as well, and has an effect on survival rates. This coupled with the scientific observation that conflicts increase when availability of the cones decreases, means cries for leadership to step up to protect humans, animals and the ecosystem alike should not go unanswered.

A small percentage of whitebark are genetically resistant to the blister rust but these trees, which might help to preserve the species, harbor no natural protection against the beetles. The US Forest Service and the National Park Service have been engaging in some restoration efforts by harvesting cones from trees resistant to the fungus, growing seedlings and relocating seedlings to suitable sites, and this is certainly a step in the right direction. Endangered species status would mean a recovery plan will be implemented and efforts would concentrate on finding ways to combat immediate threats. In the meantime, the species will continue to decline, animals, birds and the ecosystem dependent upon the whitebark will continue to suffer the consequences and humans will run a greater risk of potentially deadly encounters in bear country.