ASSESSMENT OF WHITEBARK PINE SEEDLING SURVIVAL FOR ROCKY MOUNTAIN PLANTINGS

Whitebark pine (WBP) is a keystone species of Rocky Mountain alpine and subalpine areas. A pervasive non-native fungal disease (white pine blister rust), mountain pine beetle infestation, and successional replacement by shade-tolerant competitors following decades of fire exclusion have severely reduced whitebark pine and threaten these high-elevation ecosystems. Land managers are attempting to reverse whitebark pines decline by increasing regeneration of rust-resistant trees while restoring successional processes. Restoration efforts include the planting of whitebark pine seedlings and over 200,000 seedlings have been planted on National Forest, BLM and National Park service lands. In this Rocky Mountain (RM) study, select whitebark pine plantations were surveyed and seedling survival rates and ecological data collected. The purpose of this initial study was to determine overall survival rates for planted whitebark pine seedlings and to identify environmental conditions that have promoted high seedling survival. Data were analyzed at the site, plot and tree level. Microsites created by stumps, rocks and downed logs in close proximity to WBP seedlings greatly enhanced survival, seedling height and seedling growth during the first year after planting. Potential direct solar radiation was inversely related to WBP survival. Wet planting sites were detrimental to seedling survival. Results as to the effect of fire on seedling survival were inconclusive. However for 1st year seedlings it does appear that moderate, mixed or severe burning did result in much higher survival than unburned. To further understand the environmental conditions that affect seedling survival, an experimental planting was designed and monitored using the knowledge gained from the RM study. Seedling survival in this planting was statistically significantly associated with the presence of a microsite. And increased health of seedlings was associated with the presence of beneficial mycorrhizal associates. Only seedling located in burned or unburned whitebark pine communities were colonized with native fungi and colonization was higher for burned than for unburned sites. Whitebark pine seedlings are successfully being planted and it is possible to discern how different environmental conditions are affecting the survival, height, growth and health of planted seedlings.