The proactive strategy for sustaining five-needle pine populations: An example of its implementation in the Southern Rocky Mountains

Conference Paper

Transfer Guideline: Recommendation

The imminent invasion of the non-native fungus, Cronartium ribicola J.C. Fisch., that causes white pine blister rust (WPBR) and the current mountainpine beetle (Dendroctonus ponderosae Hopkins, MPB) epidemic in northern Colorado limber pine forests will severely affect the forest regeneration cycle necessary for functioning ecosystems. The slow growth and maturity of limber pine enables trees to persist on the landscape for centuries, but without sufficient regeneration opportunities these traits will inevitably hinder the ability of limber pine to adapt to novel stresses such as WPBR or climate change. The current MPB outbreak will result in the death of many mature limber pines, including many with genetic resistance to WPBR. It will be decades until advanced regeneration develops into seed-producing mature trees in much of this region. This development will be limited further by WPBR which rapidly kills susceptible young trees. Efforts to sustain limber pine and Rocky Mountain bristlecone pine in the southern Rockies were initiated in 2001. The Northern Colorado Limber Pine Conservation Program, described here, is an example of the Proactive Strategy being implemented at a local scale. The program is a cooperative partnership between the USFS Rocky Mountain Research Station, Rocky Mountain National Park (RMNP), USFS Forest Health Management, and several Ranger Districts on the Arapaho-Roosevelt National Forest. It is designed to 1) conserve limber pine genetic diversity and 2) collect needed data to assist land managers in making informed decisions for preparation of a management plan intended to sustain resilient limber pine ecosystems in northern Colorado. The cooperative effort aims to provide immediate protection of limber pine from MPB, facilitate seed collections for WPBR resistance tests, and store and use seed for conservation, research and restoration. Seedlings are being screened for WPBR resistance to determine frequencies of resistance across the landscape among populations and to identify resistant seed trees for future seed collections. The seedling tests will also estimate population differentiation along the elevation gradient to refine seed transfer guidelines. Surveys of forest health, biotic damage, rust incidence, and trends in advanced regeneration will help project persistence of these populations after passage of the MPB epidemic. These data will provide a basis for evaluations of proactive management options on a site specific basis before northern Colorado ecosystems are impaired by WPBR; this should shorten the time frame to return to functioning ecosystems. Focusing management on proactively maintaining genetic diversity and a functional regeneration cycle will promote sustained adaptive capacity and ecosystems resilience to novel stresses such as WPBR and climate change.