Concerns Related to Concerns Related to Whitebark CommunitiesWhitebark Communities

Whitebark PineWhitebark Pine

Distribution of Whitebark Pine Distribution of Whitebark Pine in the GYEin the GYE

Whitebark pine occurs in the upper subalpine zone of western North America, particularly in the northern Rocky Mountains, where it is adapted to a harsh environment, often consisting of poor soils, steep slopes, high winds and extreme cold temperatures. This long-lived species is well known for its diverse growth forms: some trees grow straight and narrow, while others form stunted and gnarled krummholz. While its inaccessibility and sometimes crooked growth form lead to low commercial value, it is a highly valuable species ecologically. Whitebark pine is often considered a “keystone” species of the subalpine zone. Because whitebark pine can grow under conditions tolerated by few other trees, it often serves as a “nurse” plant—a plant that creates a favorable environment in which other plants can grow—for species such as subalpine fir and Engelmann spruce. Its occurrence on wind-swept ridges serves as a snow

Whitebark pine have declined over the past 50 years throughout much of its range due to the combined effects of disease, insects and forest succession. White pine blister rust—an exotic disease introduced in the early 1900s—has infected whitebark pine in parts of the Pacific Northwest, although it is possible that the severity of the blister rust infection in the GYE may be less severe overall due to the drier climate of the region. Mountain pine beetles, a native insect, are the most damaging insect to whitebark pine communities, with past outbreaks killing up to 17 million trees in the Beaverhead National Forest in one year (1932). Dwarf mistletoe can cause local damage and mortality, but is probably of relatively minor concern in the Greater Yellowstone Ecosystem. Fire regimes altered through fire suppression can allow successional species such as Engelmann spruce and subalpine fir to outcompete whitebark pine, but the extent of this concern in the GYE, where numerous large-scale fires have occurred in recent decades, is not well understood. In the past researchers believed that although severe, stand-replacing fires kill whitebark pine, post-burn reproduction would likely result in an increase in whitebark pine abundance. However, it is now clear that many factors acting simultaneously, including climate, may influence the species and the severity of disease and insect infestation. Thus, although whitebark pine recruitment is thought to be high in post-burn areas, establishment of immature trees may be less desirable than protecting mature, cone-producing trees that are being damaged by blister rust and mountain pine beetles.

Whitebark pine is a long-lived, slow-growing species that inhabits the subalpine region, typically above 8,500 feet in the GYE.

Courtesy B.R. McClelland

fence, allowing for snow accumulation. Yet, perhaps its best known role in these ecosystems is as a food source for a variety of wildlife species. Whitebark pine seeds are large and high in fat content, making them a valuable food source for more than 17 wildlife species. Whitebark pine seeds are an especially important food source for grizzly bears, which can find the seeds stockpiled in large quantities by red squirrels in middens. In the Greater Yellowstone Ecosystem (GYE), this foodsource is of such importance that annual cone production is one of the major predictors of annual survival and reproduction of the bears. Whitebark pine is classified as one of about five members—worldwide—of the stone pines in the subsection Cembrae. This group is characterized as having large, wingless seeds that are dispersed by birds.

Whitebark pine seeds are a major food source for Clark’s nutcrackers, which form a mutualistic relationship with the tree by caching seeds by the thousands, thus serving as a primary means of seed dispersal for whitebark pine.

NPS Photo

Courtesy U.S. Fish & Wildlife Service

Clark’s nutcracker

Red squirrel midden with grizzly bear digging. Courtesy IGBST

Distribution of whitebark pine in the Grizzly Bear Recovery Zone.

Courtesy USGS

CooperatorsCooperators

Greater Yellowstone Ecosystem

WHITEBARKPINE

(Pinus albicaulis)

Monitoring Program

Greater Yellowstone Ecosystem

WHITEBARKPINE

(Pinus albicaulis)

Monitoring Program

Other Efforts to Monitor Other Efforts to Monitor Whitebark PineWhitebark Pine

Cover photo courtesy of USDA Forest Service

Our effort to monitor the status of whitebark pine in the GYE is a collaborative exercise among federal agencies that administer land within the GYE. (Cooperating agencies are listed on the back of this pamphlet.) This effort represents a long-term commitment to detecting change in whitebark pine communities, which may result in changes to management of the species in the future. A preliminary field study of blister rust and whitebark pine was started in summer 2004. Our monitoring objectives are intended to answer the following question(s): Is white pine blister rust increasing within the Greater Yellowstone Ecosystem, and is the resulting mortality of whitebark pine sufficient to warrant consideration of active restoration (i.e., planting genetically resistant trees)? Specifically:• To estimate the proportion of whitebark pine trees infected with white pine blister rust, and to estimate the rate at which infection of trees is changing over time. • Within infected transects, to determine the relative severity of infection (i.e., stage and magnitude of infection and proportion of canopy kill) of white pine blister rust. • To estimate survival of whitebark pine trees, taking into account the effects of white pine blister rust infection, mountain pine beetle infestation, dwarf mistletoe parasitism and fire. • To estimate recruitment of whitebark pine trees in recently burned areas located in suitable habitat, beginning 20 years after the fire.

Objectives of the Objectives of the GYE Monitoring EffortGYE Monitoring Effort

Courtesy S. Gniadek, National Park Service In many areas of the Northwest with maritime climates, large-scale mortality of whitebark pine has occurred, such as in Glacier National Park (shown here).

Interagency Grizzly Bear Study Team

(IGBST)

Greater Yellowstone Inventory and

Monitoring Network

Yellowstone National Park

Grand Teton National Park

John D. Rockefeller, Jr. Memorial Parkway

Gallatin National Forest

Bridger-Teton National Forest

Shoshone National Forest

Caribou-Targhee National Forest

Beaverhead-Deerlodge National Forest

Custer National Forest

Forest Health Monitoring

Requests for additional copies of this brochure should be directed to the National Park Service Greater Yellowstone

Inventory and Monitoring Network.

2004

Several efforts to assess the status of white pine blister rust in whitebark pine communities have been conducted in the GYE. The USGS, in cooperation with the National Park Service, evaluated rust in Yellowstone and Glacier National Parks. In addition, the U.S. Forest Service has surveyed rust on some forest lands within the GYE. The Interagency Grizzly Bear Study Team has also been monitoring whitebark pine cone production in 19 transects within the GYE since 1980. These efforts have assisted in establishing a correlation between cone production and grizzly bear activity and demography.

Greater Yellowstone Coordinating

Committee (GYCC)

Northern Rocky Mountain Science

Center

DRAFT