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AbstractReforestation and restoration efforts have traditionally relied on “local” seed sources as planting stock. The term “local” has different meanings in different locales, since no single set of seed-collection zones has yet been widely adopted across the eastern United States. Given concerns about mitigating the effects of climate change, forest managers are increasingly seeking to move seed sources in a process called assisted migration, which would be facilitated if a common set of seed-collection zones were available. We developed a map of 245 seed-collection zones for 37 states by combining two ecologically important layers: plant hardiness zones and ecoregions. These new seed-collection zones should be used by seed collectors and nurseries to describe the origin of seed for plants and trees in the eastern United States. Common garden studies remain the gold standard for determining how far to move seed from any particular seed-collection zone. For species that have not been field-tested, seed movement that is limited either within a seed-collection zone or between adjacent seed-collection zones is a reasonable general guideline.

Eastern white pine (EWP), Pinus strobus L., is an iconic forest tree in the north woods of eastern North America. White pine blister rust, caused by Cronartium ribicola, an invasive pathogen, entered North America in the early 20th century and infected all five-needled pines across the continent. Few genotypes of eastern white pine have demonstrated consistent, elevated resistance to the pathogen, so our objective was to identify additional genotypes with resistance. Since 1970, the USDA Forest Service has identified and grafted over 800 phenotypic plus tree selections from Michigan, Wisconsin and Minnesota. A protocol to artificially inoculate one-year old seedlings was used to screen 228 genotypes along with rust-resistant and susceptible standards across a four-year period, from 2010 to 2013. We identified 25 genotypes, based on survival assessed two years after inoculation, which exceeded the resistant standard. These genotypes will be grafted into new seed orchards to aid reforestation efforts aimed at restoring this keystone species to suitable habitats where regeneration is currently hindered by blister rust on privately-held land, state forests and national forests in the Lake States region.

American chestnut restoration depends on a multitude of biological, administrative, and technological factors. Germplasm traditionally bred for resistance to the chestnut blight disease caused by the exotic pathogen Cryphonectria parasitica has been deployed on national forests in the Eastern and Southern Regions of the National Forest System (NFS) since 2009. Trees were challenged by biological factors, primarily deer browse and ink disease (caused by Phytophthora cinnamomi). Because of these problems, inferences regarding resistance or tolerance to blight are premature. Mitigation to improve success includes improved technology in seedling production for planting and selection of appropriate test sites with limited management restrictions. We suggest that chestnut restoration within the USDA Forest Service be conducted through deployment of a series of long-term multidisciplinary tests. Limitations in resources required for this effort necessitate partnership building both within and outside the agency. Vegetation establishment targets that include chestnut test plantings within the NFS should be developed.

Seed shatter dates for antelope bitterbrush (Purshia tridentata [Pursh] DC) were estimated from collections at 192 sites in Oregon and surrounding states. Shatter date was strongly correlated to elevation (r = 0.74) and an equation that included elevation, latitude, longitude, and longitude squared explained 79% of the variation in seed shatter dates. In general, earlier shatter dates were associated with more southerly latitudes, easterly longitudes, and lower elevations. Examination of climatic data confirmed the expectation that earlier shatter dates were associated with warmer sites. This information can assist those needing to schedule seed collection activities at multiple locations.

The devastation of plant communities around some primitive smelters made it apparent even centuries ago that anthropogenic pollutants could severely damage forests. At first, it appeared that the effects of these pollutants diminished rapidly with increasing distance from their sources. However, as knowledge of plant communities increased, so did the realization that the effects of some pollutants were more widespread than was obvious. Over time, the emphasis of research on the impact of air pollutants on plants has shifted from the localized effects around point sources to the effects of regionally distributed pollutants.

Progenies of individual pin oaks (Quercus palustris Muenchh.) from 19 natural and 2 cultivated populations were evaluated for severity of iron chlorosis in solution culture and soil environments. Variation among progenies of different parents was statistically significant in all cases; but rankings varied considerably among experimental environments. Population means differed significantly in 2 experiments. There was a weak geographic pattern to population means: populations from northcentral and northwestern portions of the species’ range were consistently among those most resistant to chlorosis. One population from northern Illinois appears particularly promising as a candidate for testing and selection.