Student Jesse Bunker's whitebark pine research

Whitebark pine seeds

Ecological restoration major Jesse Bunker just won a Best Student Project award from the University of Montana's Conference on Undergraduate Research. Jesse spent the summer gathering data and studying whitebark pine mortality in the alpine treeline. The pines are dying there due to outbreaks of native mountain pine beetle and the exotic fungal pathogen that causes white pine blister rust. Whitebark (Pinus albicaulis) in the alpine treeline ecotone appear to escape pine beetle attack.

Jesse BunkerThis habitat may serve as a refuge for whitebark pine during periods of extreme beetle pressure. However, treeline ecotones can only be functional refuges if they’re able to reproduce. To date, no one has documented cone production, seed set, or seed viability in treeline whitebark pine individuals, although reproductive output has been studied at lower elevations. Jesse surveyed reproductive characteristics of whitebark pine in treeline ecotones at six sites in five mountain ranges in the northern Rocky Mountains to quantify sex allocation and cone density. He harvested seed-cones to record seed-cone traits and seed quality for whitebark pine at two treeline sites. He also compared x-ray imagery and float test techniques for determining seed viability in whitebark pine.

Jesse found that: the majority of individuals within treeline ecotones are not currently reproductive, and those with reproductive structures are mostly male (83.3%); cone density is substantially lower than it is in subalpine stands; and cone size, seed potential and set, and seed size and viability appear to be drastically lower at treeline ecotones than subalpine forests.  

Images: X-ray of whitebark pine seeds showing an A) Empty Seed; B)Aborted during early development; C) Aborted late development; D) Viable Seed 

Jesse Bunker presenting at UMCUR.