Species: Dwarf Mistletoe (Arceuthobium pusillum) Global Rank: G5 State Rank: S2 Climate Change Vulnerability Index: Highly Vulnerable Confidence: Low

The range of the dwarf mistletoe extends from Minnesota and Pennsylvania north into Canada (NatureServe 2010). It occurs at the southern tier of its range in Pennsylvania but is restricted to circumboreal swamps in northeastern Pennsylvania. Current Threats: Dwarf mistletoe is threatened by deforestation, alterations to hydrology, and any other factors contributing to the general loss of its host species, black spruce. Main Factors Contributing to Vulnerability Rank: Distribution relative to natural topographic or geographic habitat barriers: Dwarf mistletoe is limited to black spruce (Picea mariana) stands that are often surrounded by a matrix of other forest types that may make migration northward difficult. Predicted sensitivity to changes in physiological thermal niche: The species is restricted to cool environments where black spruce is found. Predicted macro sensitivity to changes in precipitation, hydrology, or moisture regime: Considering the range of the mean annual precipitation across the species ’ range in Pennsylvania, the species has experienced a small precipitation variation in the past 5