“Distribution and ecological role of limber pine (Pinus flexilis) at treeline in Rocky Mountain National Park: Implications of invasive disease and climate change”

Laurel Sindewald
PhD trainee, Integrative and Systems Biology
University of Colorado Denver

Limber pine (Pinus flexilis) is a keystone and foundation species in Rocky Mountain National Park (RMNP) where it provides food for wildlife, stabilizes steep slopes, and is an early colonizer of subalpine forest after fire. Limber pine is primarily dispersed by Clark’s nutcrackers (Nucifraga columbiana), which will cache seeds into open areas and above treeline, near objects that may shelter limber pine germinants from wind stress. Limber pine has a patchy distribution in RMNP, primarily in pockets of subalpine forest, but its prevalence and ecological role above the timberline are unknown. Bioclimatic envelope models predict limber pine will advance in elevation and shrink in areal distribution with changing climate, but these do not account for topoedaphic variables, biotic interactions (including dispersal), or recruitment potential. Limber pine is also facing the spread of white pine blister rust, a disease caused by the fungal pathogen Cronartium ribicola, which reduces cone production and causes mortality in advanced stages. We aim to 1) determine limber pine’s distribution and relative abundance at treeline throughout RMNP, 2) determine which variables predict its relative abundance in treeline communities, 3) assess its ecological role in treeline communities, 4) assess its reproductive potential in terms of seed viability at treeline, and 5) estimate the prevalence of blister rust infection in treeline limber pine.