Forest Service scientists at the agency’s Northern Research Station and forest managers in the Allegheny High Plateau Ecoregion are working to understand changes in black cherry health, growth, and seed production. The scientists in Irvine, Penn., summarized and presented results from more than 40 years of data to forest managers. Data from the Allegheny National Forest (ANF) and the Pennsylvania Department of Conservation and Natural Resources Bureau of Forestry show increases in black cherry tree mortality. Health issues include outbreaks of native insects affecting mature black cherry; a reversal in the competitive relationship of black cherry and black birch seedlings and saplings that has left black birch outgrowing black cherry; less regular black cherry seed production; and increased frequency and severity of fungal pathogens on black cherry seedlings. Together, scientists and foresters developed hypotheses to explain these changes, including insect defoliations, an increase in pathogens specific to cherry, reduced inputs of nitrate nitrogen, and changing deer impact. With the ANF, the scientists are investigating the nitrogen hypothesis through fertilization trials. They are studying the dynamics of mixed-species regeneration in forests with high proportions of cherry. The cooperation among managers and scientists across agency boundaries demonstrates that manager observations can strengthen and accelerate research studies.