Landscape analysis of risk factors for white pine blister rust in the Mixed Forest Province of Minnesota, U.S.A.

The abundance of eastern white pine (Pinus strobus L.) has been significantly reduced in northeastern Minnesota over the past 120 years. White pine blister rust (WPBR), a commonly lethal fungal disease of white pine, was introduced in Minnesota in approximately 1914 and now, along with other factors such as herbivore browsing, poses a major challenge to attempts to reestablish white pines in the region. A map delineating broad WPBR hazard zones for the Lake States region was prepared in 1964. We created a higher resolution map that estimates the spatial variability of WPBR hazard in the Laurentian Mixed Forest Province of Minnesota using modern geographic information system techniques and readily available spatial databases. The new map has significantly higher resolution than the old and demonstrates that even within areas previously classified as "high hazard", there are significant acreages of "low-hazard" areas where white pine regeneration may be possible. Our analyses are consistent with previous work in the Lake States region, showing that climate, topographic characteristics, and distance from water bodies and wetlands have a strong influence on WPBR infection hazard. We also present methods for analyzing forest conditions at regional scales using commonly available spatial data sets.