Bioclimatic modeling predicts potential distribution of Armillaria solidipes and Pseudotsuga menziesii (Douglas-fir) under contemporary and changing climates in the interior western U.S.A

Pseudotsuga menziesii (Douglas-fir) is a dominant component of forest stands in much of western North America. It is an important tree to the timber industry, yielding more timber than any other species in North America. It is also extremely important for wildlife as habitat and food. Many small birds and mammals feed on its seeds . Armillaria solidipes [pending vote to conserve A. ostoyae (Redhead et al. 2011)] is also a key component of forest stands throughout much of western North America (Hanna 2005). It is an aggressive pathogen of conifers causing tree mortality and growth loss (Cruickshank 2000). In particular, P. menziesii (and specifically the inland subspecies) is one species along with Abies grand is (grand fir) and A. lasiocarpa (subalpine fir) that can have the highest rates of susceptibly to A. solidipe's (McDonald et al. 1987a). These species have a long history of co-evolution and codistribution over millions of years. Under the host/stress/saprogen concept, disease develops when these secondary pathogens already on-site invade host tissue after environmental stress (Houston 1992). These stressors include climate, human disturbance, arthropod pests, and other pathogens. Such diseases are believed to increase in severity and prevalence under climate change as trees become progressively maladapted to their environments (Kliejunas et al. 2009). In this study, we use DNA-based methods to confirm species identification and utilize location-specific climate data for bioclimatic modeling to predict where A. solidipes is likely to occur and cause increased disease pressure on P. menziesii under changing climatic conditions.