Whitebark pine encroachment into lower elevation sagebrush grasslands in southwest Montana, USA (Mountain Views)

Abstract

The collective impacts of fire exclusion polices, mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreaks, and white pine blister rust (Cronartium ribicola J.C. Fisch) infections have resulted in a rapid decline of whitebark pine (Pinus albicaulis Engelm.) forests in western North America over the last several decades (Arno 1986, Kendall and Keane 2001, Goeking and Izlar 2018). Especially distressing are the projected declines in these iconic forests because of future changes in climate (Warwell et al. 2007, Chang et al. 2014). Future warmer and drier climates could result in increases in the frequency of wildland fire (Flannigan et al. 2009, Abatzoglou and Williams 2016, Schoennagel et al. 2017) and mountain pine beetle outbreaks (Carroll et al. 2003, Wong and Daniels 2016), but it is also speculated that it will also increase white pine blister rust infections (Landguth et al. 2017, Wyka et al. 2018). However, more alarming is that many statistical modeling studies have shown significant reduction in the biophysical conditions that define suitable whitebark pine habitat over the next century (Warwell et al. 2007, Chang et al. 2014). Historically, whitebark pine forests composed about 10-15% of the upper subalpine zone of the northern Rocky Mountains (Arno and Weaver 1990) with around 48% of that in wilderness landscapes, but future projections for these iconic forests suggest that they may inhabit as little as 0.5-7.0% by 2070-2100 (Hansen and Phillips 2015).

Citation

Keane, Robert; Flanary, Sarah. 2019. Whitebark pine encroachment into lower elevation sagebrush grasslands in southwest Montana, USA (Mountain Views). Mountain Views. 13(2): 22-27.