It is common to find mature whitebark pine trees well over 400 years of age as seen in this image, especially on harsh growing sites. Photo by Robert E. Keane.
Whitebark pine (Pinus albicaulis
) forests are declining across most of their range in North America because of the combined effects of mountain pine beetle (Dendroctonus ponderosae
) outbreaks, fire exclusion policies, and the exotic pathogen Cronartium ribicola
, which infects five-needle white pines and causes the disease white pine blister rust. Predicted changes in climate may exacerbate whitebark pine decline by (1) accelerating succession to more shade tolerant conifers, (2) creating environments that are unsuitable for the species, (3) increasing the frequency and severity of mountain pine beetle outbreaks and wildland fire events, and (4) facilitating the spread of blister rust. Yet, whitebark pine tolerates a variety of stressful conditions and the broad genetic diversity to adapt to changes in climate and disturbance.
In this report, we present guidelines for restoring whitebark pine under future climates based on an existing international rangewide restoration strategy. General restoration guidelines considering effects of climate change are given for each of the strategy’s guiding principles: (1) promote resistance to blister rust, (2) conserve genetic diversity, (3) save seed sources, and (4) employ restoration treatments. We then provide specific guidelines for each of the strategy’s actions: (1) assess condition, (2) plan activities, (3) reduce disturbance impacts, (4) gather seed, (5) grow seedlings, (6) protect seed sources, (7) implement restoration treatments, (8) plant burned areas, (9) monitor activities, and (10) support research.
We used information from two sources to account for climate change impacts on whitebark pine restoration activities. First, we conducted an extensive and comprehensive review of the literature to assess climate change impacts on whitebark pine ecology and management. Second, we augmented this review with results from a comprehensive simulation experiment using the spatially explicit, ecological process model FireBGCv2. This modeling experiment simulated various climate change, management, and fire exclusion scenarios. We also ran FireBGCv2 to evaluate the effects of specific rangewide restoration actions with and without climate change. We analyzed two simulated response variables (whitebark pine basal area, proportion of the landscape dominated by whitebark pine) to explore which restoration scenarios are likely to succeed.
Our findings indicate that management intervention actions such as planting rust-resistant seedlings and employing proactive restoration treatments can return whitebark pine to the high mountain settings of western North America to create resilient upper subalpine forests for the future. The report is written as companion guide to the rangewide restoration strategy for planning, designing, implementing, and evaluating fine-scale restoration activities for whitebark pine by addressing climate change impacts.
Whitebark pine will continue to decline over the next several decades, mostly from white pine blister rust and mountain pine beetle mortality and only indirectly by direct climate change impacts on regeneration and growth.
This decline can be reversed with proactive restoration actions; if no restoration activities are attempted, whitebark pine forests will continue to decline and become a minor, if not missing, component on the high elevation landscapes in western North America.
We found that the recommendations proposed in the rangewide strategy (Keane et al. 2012b) are still valid. Only a few modifications to the rangewide strategy are needed to account for future changes in climate.
We also found that whitebark pine can do quite well under future climates on many landscapes, especially with more frequent fire, but there are some landscapes where whitebark pine will continue to decline.
This effort was mostly funded by the Great Northern Landscape Conservation Cooperative.