Climate Change and Collapse of Whitebark Pine Ecosystems chaired by Jess Logan

Management of Whitebark Pine in the GYE

Liz Davy — Mon, 22 Jun 2009 15:40:00 PDT

This presentation will focus on the development and use of a whitebark pine restoration strategy for the Greater Yellowstone Ecosystem.

The Bear Facts: Implications of Whitebark Pine Loss for Yellowstone Grizzlies

Louisa Willcox — Mon, 22 Jun 2009 10:50:00 PDT

Whitebark pine is a foundation species, and barometer of the health of high elevation forests ecosystems in the West. It provides food and cover for numerous wildlife species, including the Clark’s nutcracker, crossbill, grosbeak, red squirrel and chipmunk. Whitebark pine is particularly important in the Greater Yellowstone Ecosystem (GYE), where it provides an essential food source for the imperiled Yellowstone grizzly bear. We will review the current scientific knowledge about the relationship between Yellowstone grizzlies and whitebark pine seeds, and examine the implications of the collapse of whitebark pine. High-fat whitebark pine seeds are important for female reproductive success: females produce larger litters after abundant whitebark pine seed crop years. And, by growing at high elevations in remote country, whitebark pine helps keep grizzlies out of harmís way, reducing human-grizzly conflicts and mortality rates. After poor whitebark seed crop years, grizzly bear mortality in the GYE occurs at more than twice the rate than after good pine seed years. The collapse of whitebark pine in the GYE bodes ill for the future of the Yellowstone grizzly bear population. We will demonstrate the connection between recent years of excessive human-caused grizzly bear mortality and declining whitebark pine in the GYE. We will summarize recent analysis of additional suitable grizzly habitat within the GYE and between the GYE and other grizzly populations in the lower 48 states and Canada. Using recent over-flight assessments of whitebark pine mortality from mountain pine beetle, we will identify priority areas for bear conservation in the GYE. We will demonstrate the need for: 1.) improved measures to reduce human-bear conflicts; and, 2.) new policies that allow Yellowstone bears to access additional habitat needed to offset the loss of whitebark pine.

Mountain Pine Beetle Outbreak Dynamics in High Elevation Forests: Influence of Climate Change and Tree Chemistry

Barbara J. Bentz et al. — Mon, 22 Jun 2009 11:10:00 PDT

Many species within Pinus are considered suitable hosts for mountain pine beetle (Dendroctonus ponderosa). Largescale mountain pine beetle outbreaks are most often associated with a just a few Pinus species, possibly due to their distribution and thermal habitat. For example, lodgepole pine (P. contorta) grows as relatively contiguous homogenous forests at lower elevations across the western U.S. and Canada. As a consequence, the majority of mountain pine beetle outbreaks the past century have been observed in this species. Conversely, the unsuitable thermal habitat of high elevation white pine forests has hampered mountain pine beetle outbreaks the past century, except during periods of warming (such as the early 1930ís). Mountain pine beetle activity in high elevation white pine forests has increased dramatically within the past decade. Our recent research suggests that temperature-dependent shifts in mountain pine beetle voltinism have influenced population success and resultant tree mortality in high elevation forests. Differences in tree chemistry between lodgepole pine and whitebark pine (P. albicaulis) may also play a role in mountain pine beetle outbreak dynamics.

An Individual Based Model of Mountain Pine Beetle Responses to Climate and Host Resistance

Jacques Regniere et al. — Mon, 22 Jun 2009 11:30:00 PDT

We have developed a model describing the responses of mountain pine beetle to daily fluctuations of temperature, in terms of development, survival and reproduction. The model also describes the aggregation, attack, and competition of beetles in pine stands. Built in an individual based framework, using an object-oriented approach, this model can predict the response of beetle populations to climatic conditions and host plant resistance and distribution, at the stand level. We are using this model to better understand the interaction between climate and host plant resistance that determine population growth rates in various environments. We will focus on the contrasting population performance of MPB on whitebark pine compared to lodgepole pine.

Rust and Beetle Interactions in Pinus albicaulis Ecosystems

Nancy Bockino et al. — Mon, 22 Jun 2009 11:50:00 PDT

Current mountain pine beetle activity in whitebark pine ecosystems in the Greater Yellowstone Ecosystem is unprecedented in extent and severity. Dynamics among beetles, white pine blister rust, and climate change are placing this foundation species in a precarious state. Stand- and tree-level data was recorded to quantify how the severity of rust and the presence of an alternate host influence the susceptibility of whitebark to selection by the beetle. Data reveal that 52% of whitebark sampled were dead, 70% attacked by the beetle, 85% infected with rust, and 61% were afflicted with both. Beetle activity was lower than expected in trees with low severity blister rust and increased significantly in trees with high rust severity. On sites with two potential host species, whitebark pine is preferentially selected over lodgepole pine. This work reveals that blister rust increases whitebark selection probability by, and that lodgepole pine are not the preferred host of, the mountain pine beetle. The interaction between blister rust and mountain pine beetle, and the preference for whitebark pine may enhance whitebark pine mortality, population decline, and alter whitebark demography and the ecological processes to which these trees are critical.

Interactions of Climate, Host Tree Defenses, White Pine Blister Rust and the Mountain Pine Beetle in Whitebark Pine

Diana Six — Mon, 22 Jun 2009 13:30:00 PDT

The dynamics of insect herbivore populations are seldom driven by a single dominant factor, but rather, by a combination of interacting factors. In this presentation, we discuss how climate, an exotic disease, and host tree defenses, may interact to affect mountain pine beetle population dynamics in a high elevation tree, whitebark pine. Warming trends have allowed mountain pine beetles to move higher in elevation where they are now well established and developing widespread outbreaks in whitebark pine. While increased temperatures are the proximate cause of this elevational expansion, other factors appear to exacerbate the beetle’s impact on the tree once it is present. Evidence is accumulating that whitebark pine may be a superior host for the beetle compared with its more common co-evolved host, lodgepole pine. In stands where lodgepole and whitebark pine co-exist, the beetle exhibits a strong preference for whitebark pine. This preference appears to be related to lower innate defenses and higher stored reserves in whitebark pine relative to lodgepole pine. Additionally, infection by Cronartium ribicola, the causal agent of white pine blister rust, strongly influences beetle preference for individual whitebark pine, with trees exhibiting higher levels of infection significantly more preferred than those exhibiting low levels of infection. Furthermore, sapwood moisture in whitebark pine decreases as infection severity increases; indicating that infection by the pathogen has an effect on water relations within the tree. Sapwood moisture also declines much more rapidly in whitebark than lodgepole pine under drought conditions, indicating this tree may become stressed (and subsequently susceptible to beetles) more rapidly in years when precipitation is low. The combination of low tree defenses, white pine blister rust, and altered precipitation patterns may, alone and in combination, enhance the ability of the beetle to kill trees in high elevations.

Whitebark Pine Ecosystem Collapse in the Greater Yellowstone Ecosystem: Fiction Or Fact?

J. Logan et al. — Mon, 22 Jun 2009 14:10:00 PDT

Widespread outbreaks of mountain pine beetles (MPB) are occurring throughout the range of this native insect. Mountain pine beetles are among a small group of so called aggressive bark beetles that must kill its host to successfully reproduce, and episodic outbreaks of this insect are truly impressive events where otherwise healthy trees are killed in large numbers. Periodic outbreaks of mountain pine beetles are a common occurrence in its major pine host, lodgepole pine, an r-selected species that is highly resilient to MPB disturbance. The current outbreaks are unusual in several respects, including the occurrence in habitats where previously outbreaks either did not occur, or were limited in scale. In this presentation, we address widespread outbreaks that are ongoing in high-elevation, whitebark pine where, due to an inhospitable habitat, past outbreaks were infrequent and short-lived. Unlike lodgepole pine, whitebark pine is a strongly K-selected species with unknown resilience to mountain pine beetle. In this presentation, we address the basic question: are these outbreaks in whitebark pine truly unprecedented and a threat to continuation of this important ecosystem, or are they simply a case of disturbance leading forest renewal? In particular, we address widespread outbreaks that are occurring in the Greater Yellowstone Ecosystem, an U. N. World Heritage Site where whitebark pine plays an essential role in maintaining the unique characteristics of this largely intact ecosystem. We apply the principles of disturbance ecology to evaluate this question. Namely, we consider the historic range of variability, system resiliency to MPB disturbance and the domain of attraction of whitebark pine ecosystems to large-scale MPB disturbance. We conclude loss of ecological functionality in the Greater Yellowstone Ecosystem is almost certain with the projected climate trajectory of global warming, and long-term loss of the climax whitebark pine forests is a finite possibility.

Mapping and Monitoring Mountain Pine Beetle Outbreaks in Whitebark Pine Ecosystems with Satellite Imagery

J. Hicke et al. — Mon, 22 Jun 2009 14:30:00 PDT

Whitebark pine ecosystems are currently subjected to multiple threats, including extensive outbreaks of mountain pine beetle in recent years. These infestations have killed substantial numbers of trees in the Central and Northern Rocky Mountains, including in the Greater Yellowstone Ecosystem and in Idaho. Monitoring outbreaks in these rugged, mountainous regions for ecological studies is facilitated by spatially extensive remotely sensed imagery. Here we report on studies using a variety of satellite imagery to map pine mortality resulting from infestations of mountain pine beetle, with a focus on whitebark pine forests. We will discuss methods for classifying tree mortality using fine spatial resolution QuickBird imagery at Railroad Ridge, Idaho. Masking and maximum likelihood classification methods were developed to partition the landscape into non-vegetated, green herbaceous, brown herbaceous, live tree, and dead tree classes. We assessed the accuracy of this classification using an independent set of image pixels as well as field measurements of live and dead trees; high accuracies were achieved. We will also report on methods to utilize moderate-resolution (Landsat) and coarse-resolution (MODIS) satellite imagery to map tree mortality with single- and multi-date methods. We will illustrate the ecological use of classified imagery by assessing spatial and temporal dynamics of the imagery as well as the distribution of mortality with respect to topographic variables.

Landscape Assessment and Monitoring of Mountain Pine Beetle Mortality in Greater Yellowstone Ecosystem Whitebark Pine

W.Wallace Macfarlane et al. — Mon, 22 Jun 2009 14:30:00 PDT

Since 2000, USDA Forest Service Aerial Detection Surveys (ADS) and ground-based surveys indicate mountain pine beetle (MPB) outbreaks have caused catastrophic loss of whitebark pine (WBP) in the Greater Yellowstone Ecosystem (GYE). However, the full extent of the damage is unknown because of limitations to the traditional survey methods. We describe a new method aimed at quickly and cost-effectively documenting landscape conditions. The method utilizes low-flying airplane overflights, Global Positioning System (GPS), and Geographic Information System (GIS) technologies along with digital photography to categorize MPB outbreaks based on a new landscape classification scheme. We conducted a pilot study consisting of four overflights covering large portions of the Teton Wilderness, Wind River, Absaroka, Gallatin, and Beartooth mountain ranges. Results indicate our approach is a reliable and repeatable method to assess the extent and severity of MPB related WBP mortality. Significant MPB activity was documented throughout the area surveyed - only the center core of the Wind River Range, the Beartooth Plateau and Northern Gallatin Range remain in a healthy condition. A vast area of approximately 450,000 acre covering the northern Wind River Range, Southwestern Absoroka Range and the Teton Wilderness, was found to be the most heavily impacted. Here the overflights document an ecological collapse of the WBP ecosystem due to unprecedented MPB outbreaks. This pilot study provided an independent validation of previous computer simulations and corroborates the general trend indicated by US Forest Service ADS. Additionally, results extend previous information in several ways: (1) The outbreaks are outpacing computer simulations that were based on climate warming predictions. (2) Our approach identified greater mortality when compared to the ADS results. (3) Overflights were conducted in several regions of the GYE not recently or never surveyed by ADS, and therefore provide a more comprehensive documentation of MPB impact in WBP than previously available.

Whitebark Pine Assessment and Restoration in Central Rockies National Parks

Kelly McCloskey et al. — Mon, 22 Jun 2009 14:50:00 PDT

White pine blister rust and mountain pine beetle are having profound effects on the whitebark pine in the National Parks of the Central Rockies. The importance of this species for ecosystem services including water retention at high elevations, slope stabilization, and providing a highly nutritional food source for grizzly bears and other wildlife species, has been recognized by National Park Service managers for several decades. Analysis of monitoring activities conducted from the 1990ís, and renewed efforts in 2003-2008 show that blister rust and blister rust-related mortality is increasing in stands throughout the parks and forests of the Greater Yellowstone Ecosystem, as well as in Montana and Washington parks. The park service is participating in projects to map mortality, determine if successful regeneration is occurring in these stands, and develop restoration strategies. Parks are preserving whitebark pine genetics through operational cone collections, and participating in the US Forest Service-lead whitebark pine genetic improvement and restoration program to identify genetically rust resistant trees. Parks are laying the foundation to begin restoration activities in whitebark pine stands where mortality is high and regeneration success is low.