RELATIONSHIP BETWEEN POLLINATION DEFICIENCY AND DECLINE OF BLACK CHERRY REGENERATION IN THE ALLEGHENY NATIONAL FOREST

Black cherry is the highest value timber species in the Northeastern US, with significant production in the Allegheny National Forest (ANF) of Pennsylvania. PA grows the highest quality black cherry in the world, and sales of cherry lumber and products account for a significant portion of the value of timber sales in the state. However, seed production and regeneration have been declining since 2000 in the ANF, threatening this important industry. Since black cherry requires insect pollination to produce viable seeds, the observed reductions suggest that pollination in these regions may be compromised. Declines in wild pollinator species have been broadly documented in agricultural regions, but we have little understanding of pollinator communities within forested landscapes, which are necessary for production of flowering timber trees such as black cherry, and the habitats that support these pollinators. Many factors that impact pollinator species (changing climate, site conditions, and stand structure) will also impact tree health and productivity. Our goal is to understand the relationship between habitat factors that support a robust community of pollinators and production of abundant viable black cherry seeds for regeneration. Armed with this knowledge, we will offer recommendations to the PA Bureau of Forestry and the US Forest Service for increasing black cherry seed production, and in turn, improving regeneration of black cherry in PA forests.Our objectives are to: (1) comprehensively assess the pollinators of black cherry trees and identify the most important pollinators, and (2) examine the degree to which viable seed production in the ANF is determined by the presence and abundance of suitable pollinator species, and how pollinator species and viable seed production relate to important biotic and abiotic factors in the landscape.In Objective 1, we will identify the key pollinators of this important timber species through a series of detailed observational and sampling studies, using easily accessible trees in landscapes that support diverse pollinator communities. In Objective 2, we will conduct larger landscape scale studies in the ANF to determine if the presence of these pollinator species and/or overall pollinator community abundance and diversity influence fruit and seed production (yield). We will simultaneously assess other aspects of landscape quality, stand structure, and tree health. We expect that the percentage of successful fruit set will correlate with the abundance and diversity of key pollinator species, but we also expect these parameters and the density of flowers/tree will vary with a number of biotic and abiotic factors.The results of these studies will help forest managers develop methods for assessing the quality of pollinator communities and landscapes for supporting viable seed production of black cherry in the ANF. Our findings will also provide recommendations for practices to improve pollination, viable seed set, and regeneration. New information will allow forest managers to determine which sites are most likely to respond favorably to interventions, such as thinning or shelterwood cutting.