Whitebark pine monitoring: 2015 results from Crater Lake National Park and Lassen Volcanic National Park

Smith, Sean; Chung-MacCoubrey, Alice

Whitebark pine trees (Pinus albicaulis, PIAL) in Lassen Volcanic National Park (LAVO) and Crater Lake National Park (CRLA) are vulnerable to several stressors such as exotic pathogens and climate change, and have been recognized as a high priority vital sign for the Klamath Inventory and Monitoring Network (KLMN). The distribution of whitebark pine ranges from the southern Sierra Nevada to British Columbia and the northern Rockies (Tomback et al. 2001), and occurs in a variety of habitats from montane, upper subalpine, and treeline zones. Currently, populations of whitebark pine are declining in the northern Cascades and Rocky Mountains, but Sierra Nevada populations are not showing similar declines (Nesmith 2015). Given that the Klamath Network is between these regions that are experiencing differing population trends and that similar stressors have been identified in KLMN parks, park managers are concerned about the future of these ecologically valuable communities in the Klamath Region. Monitoring white pine forest community dynamics will allow for the detection of downward trends and assist with identifying potential need for management intervention. KLMN has been monitoring PIAL since 2012 and this monitoring is being closely coordinated with monitoring of white pine species in other networks by using a common protocol (McKinney et al. 2012) (limber pine [P. flexilis] in the Upper Columbia Basin Network [UCBN]; whitebark pine and foxtail pine (P. balfouriana), in the Sierra Nevada Network [SIEN]). We are measuring forest community demographics and agents of PIAL mortality within 50x50 m (0.25 ha) plots. Thus, information from this monitoring project will contribute meaningfully to the broader regional assessment of the status and trends of white pine species across western North America. This report describes the first year revisiting whitebark pine (Pinus albicaulis) sites established in 2012. We revisited 10 sites each at Crater Lake and Lassen Volcanic National Parks. This project implements methodology outlined by McKinney et al. (2012). Here we present data and observations from our 2015 monitoring effort, and where applicable we make comparisons between the 2012 and 2015 data. Whitebark pine trees comprised 14% of the basal area measured at Crater Lake and 18% at Lassen. On average, blister rust infected 19% and 16% of whitebark pine trees in plots at Crater Lake and Lassen, respectively. We found white pine blister rust (Cronartium ribicola) to be the main cause of death among recently dead whitebark pines. We estimate blister rust killed 50% at CRLA and 69% at Lassen of all dead PIAL trees (this includes trees with unknown cause of death). Several of the trees with an unknown cause of death (cause of death was obscured by weathering or decay) had inactive/active cankers in 2012; likely these trees died of blister rust, which would increase estimates of blister rust mortality to 71% and 78% at CRLA and LAVO, respectively. Pine beetles were not responsible for killing any whitebark pine between 2012 and 2015. We found no significant difference between the 2012 and 2015 seedling densities.

Whitebark pine monitoring: 2015 results from Crater Lake National Park and Lassen Volcanic National Park

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